From 517fb88329fea0ab20ca0b4a559096193d2ffa3a Mon Sep 17 00:00:00 2001
From: localvar <localvar@hotmail.com>
Date: Tue, 24 Dec 2019 17:16:58 +0800
Subject: [PATCH 01/35] subscription (WIP)

---
 src/client/inc/tsclient.h          |   2 +
 src/client/src/tscServer.c         |   5 +-
 src/client/src/tscSql.c            |   5 +
 src/client/src/tscSub.c            | 279 ++++++++++++++++++++---------
 src/client/src/tscUtil.c           |   2 +-
 src/inc/taos.h                     |   9 +-
 src/inc/taosmsg.h                  |   2 +
 src/system/detail/src/vnodeShell.c |   1 +
 tests/examples/c/subscribe.c       |  67 +++----
 9 files changed, 237 insertions(+), 135 deletions(-)

diff --git a/src/client/inc/tsclient.h b/src/client/inc/tsclient.h
index 6adf2f1be1..e91b05d104 100644
--- a/src/client/inc/tsclient.h
+++ b/src/client/inc/tsclient.h
@@ -334,6 +334,7 @@ typedef struct {
   int                   rspType;
   int                   rspLen;
   uint64_t              qhandle;
+  int64_t               uid;
   int64_t               useconds;
   int64_t               offset;  // offset value from vnode during projection query of stable
   int                   row;
@@ -380,6 +381,7 @@ typedef struct _sql_obj {
   uint32_t          queryId;
   void *            thandle;
   void *            pStream;
+  void *            pSubscription;
   char *            sqlstr;
   char              retry;
   char              maxRetry;
diff --git a/src/client/src/tscServer.c b/src/client/src/tscServer.c
index bdac9185eb..9a88ee9fc4 100644
--- a/src/client/src/tscServer.c
+++ b/src/client/src/tscServer.c
@@ -1531,7 +1531,7 @@ static char* doSerializeTableInfo(SSqlObj* pSql, int32_t numOfMeters, int32_t vn
     SMeterSidExtInfo *pMeterInfo = (SMeterSidExtInfo *)pMsg;
     pMeterInfo->sid = htonl(pMeterMeta->sid);
     pMeterInfo->uid = htobe64(pMeterMeta->uid);
-    
+    pMeterInfo->skey = tscGetSubscriptionProgress(pSql, pMeterMeta->uid);
     pMsg += sizeof(SMeterSidExtInfo);
   } else {
     SVnodeSidList *pVnodeSidList = tscGetVnodeSidList(pMetricMeta, pMeterMetaInfo->vnodeIndex);
@@ -1542,6 +1542,7 @@ static char* doSerializeTableInfo(SSqlObj* pSql, int32_t numOfMeters, int32_t vn
       
       pMeterInfo->sid = htonl(pQueryMeterInfo->sid);
       pMeterInfo->uid = htobe64(pQueryMeterInfo->uid);
+      pMeterInfo->skey = tscGetSubscriptionProgress(pSql, pMeterMeta->uid);
       
       pMsg += sizeof(SMeterSidExtInfo);
       
@@ -3535,7 +3536,7 @@ int tscProcessRetrieveRspFromVnode(SSqlObj *pSql) {
   pRes->numOfRows = htonl(pRetrieve->numOfRows);
   pRes->precision = htons(pRetrieve->precision);
   pRes->offset = htobe64(pRetrieve->offset);
-
+  pRes->uid = pRetrieve->uid;
   pRes->useconds = htobe64(pRetrieve->useconds);
   pRes->data = pRetrieve->data;
 
diff --git a/src/client/src/tscSql.c b/src/client/src/tscSql.c
index c9d9050a29..404c3f947b 100644
--- a/src/client/src/tscSql.c
+++ b/src/client/src/tscSql.c
@@ -627,6 +627,11 @@ TAOS_ROW taos_fetch_row(TAOS_RES *res) {
       rows = taos_fetch_row_impl(res);
     }
 
+    if (rows != NULL && pSql->pSubscription != NULL) {
+      TSKEY ts = *(TSKEY*)rows[pCmd->fieldsInfo.numOfOutputCols - 1];
+      tscUpdateSubscriptionProgress(pMeterMetaInfo->pMeterMeta->uid, ts);
+    }
+
     // check!!!
     if (rows != NULL || pMeterMetaInfo->vnodeIndex >= pMeterMetaInfo->pMetricMeta->numOfVnodes) {
       break;
diff --git a/src/client/src/tscSub.c b/src/client/src/tscSub.c
index f2e9395c68..af3a576377 100644
--- a/src/client/src/tscSub.c
+++ b/src/client/src/tscSub.c
@@ -22,125 +22,232 @@
 #include "tsclient.h"
 #include "tsocket.h"
 #include "ttime.h"
+#include "ttimer.h"
 #include "tutil.h"
+#include "tscUtil.h"
 
-typedef struct {
-  void *     signature;
-  char       name[TSDB_METER_ID_LEN];
-  int        mseconds;
-  TSKEY      lastKey;
-  uint64_t   stime;
-  TAOS_FIELD fields[TSDB_MAX_COLUMNS];
-  int        numOfFields;
-  TAOS *     taos;
-  TAOS_RES * result;
+typedef struct SSubscriptionProgress {
+  int64_t uid;
+  TSKEY key;
+} SSubscriptionProgress;
+
+typedef struct SSub {
+  void *                  signature;
+  TAOS *                  taos;
+  void *                  pTimer;
+  SSqlObj *               pSql;
+  int                     interval;
+  TAOS_SUBSCRIBE_CALLBACK fp;
+  void *                  param;
+  int                     numOfMeters;
+  SSubscriptionProgress * progress;
 } SSub;
 
-TAOS_SUB *taos_subscribe(const char *host, const char *user, const char *pass, const char *db, const char *name, int64_t time, int mseconds) {
-  SSub *pSub;
 
-  pSub = (SSub *)malloc(sizeof(SSub));
-  if (pSub == NULL) return NULL;
-  memset(pSub, 0, sizeof(SSub));
+static int tscCompareSubscriptionProgress(const void* a, const void* b) {
+  return ((const SSubscriptionProgress*)a)->uid - ((const SSubscriptionProgress*)b)->uid;
+}
 
-  pSub->signature = pSub;
-  strcpy(pSub->name, name);
-  pSub->mseconds = mseconds;
-  pSub->lastKey = time;
-  if (pSub->lastKey == 0) {
-    pSub->lastKey = taosGetTimestampMs();
+TSKEY tscGetSubscriptionProgress(SSqlObj* pSql, int64_t uid) {
+  if( pSql == NULL || pSql->pSubscription == NULL)
+    return 0;
+
+  SSub* pSub = (SSub*)pSql->pSubscription;
+  for (int s = 0, e = pSub->numOfMeters; s < e;) {
+    int m = (s + e) / 2;
+    SSubscriptionProgress* p = pSub->progress + m;
+    if (p->uid > uid)
+      e = m;
+    else if (p->uid < uid)
+      s = m + 1;
+    else
+      return p->key;
   }
 
-  taos_init();
-  pSub->taos = taos_connect(host, user, pass, NULL, 0);
-  if (pSub->taos == NULL) {
-    tfree(pSub);
-  } else {
-    char qstr[256] = {0};
-    sprintf(qstr, "use %s", db);
-    int res = taos_query(pSub->taos, qstr);
-    if (res != 0) {
-      tscError("failed to open DB:%s", db);
-      taos_close(pSub->taos);
-      tfree(pSub);
-    } else {
-      snprintf(qstr, tListLen(qstr), "select * from %s where _c0 > now+1000d", pSub->name);
-      if (taos_query(pSub->taos, qstr)) {
-        tscTrace("failed to select, reason:%s", taos_errstr(pSub->taos));
-        taos_close(pSub->taos);
-        tfree(pSub);
-        return NULL;
-      }
-      pSub->result = taos_use_result(pSub->taos);
-      pSub->numOfFields = taos_num_fields(pSub->result);
-      memcpy(pSub->fields, taos_fetch_fields(pSub->result), sizeof(TAOS_FIELD) * pSub->numOfFields);
+  return 0;
+}
+
+void tscUpdateSubscriptionProgress(SSqlObj* pSql, int64_t uid, TSKEY ts) {
+  if( pSql == NULL || pSql->pSubscription == NULL)
+    return;
+
+  SSub* pSub = (SSub*)pSql->pSubscription;
+  for (int s = 0, e = pSub->numOfMeters; s < e;) {
+    int m = (s + e) / 2;
+    SSubscriptionProgress* p = pSub->progress + m;
+    if (p->uid > uid)
+      e = m;
+    else if (p->uid < uid)
+      s = m + 1;
+    else {
+      p->key = ts + 1;
+      break;
     }
   }
+}
+
+
+static SSub* tscCreateSubscription(STscObj* pObj, const char* sql) {
+  SSub* pSub = calloc(1, sizeof(SSub));
+  if (pSub == NULL) {
+    globalCode = TSDB_CODE_CLI_OUT_OF_MEMORY;
+    tscError("failed to allocate memory for subscription");
+    return NULL;
+  }
+
+  SSqlObj* pSql = calloc(1, sizeof(SSqlObj));
+  if (pSql == NULL) {
+    globalCode = TSDB_CODE_CLI_OUT_OF_MEMORY;
+    tscError("failed to allocate SSqlObj for subscription");
+    goto failed;
+  }
+
+  pSql->signature = pSql;
+  pSql->pTscObj = pObj;
+
+  char* sqlstr = (char*)malloc(strlen(sql) + 1);
+  if (sqlstr == NULL) {
+    tscError("failed to allocate sql string for subscription");
+    goto failed;
+  }
+  strcpy(sqlstr, sql);
+  strtolower(sqlstr, sqlstr);
+  pSql->sqlstr = sqlstr;
+
+  tsem_init(&pSql->rspSem, 0, 0);
+  tsem_init(&pSql->emptyRspSem, 0, 1);
+
+  SSqlRes *pRes = &pSql->res;
+  pRes->numOfRows = 1;
+  pRes->numOfTotal = 0;
+
+  pSql->pSubscription = pSub;
+  pSub->pSql = pSql;
+  pSub->signature = pSub;
+  return pSub;
+
+failed:
+  if (sqlstr != NULL) {
+    free(sqlstr);
+  }
+  if (pSql != NULL) {
+    free(pSql);
+  }
+  free(pSub);
+  return NULL;
+}
+
+
+static void tscProcessSubscribeTimer(void *handle, void *tmrId) {
+  SSub *pSub = (SSub *)handle;
+  if (pSub == NULL || pSub->pTimer != tmrId) return;
+
+  TAOS_RES* res = taos_consume(pSub);
+  if (res != NULL) {
+    pSub->fp(pSub->param, res, 0);
+    taos_free_result(res);
+  }
+
+  taosTmrReset(tscProcessSubscribeTimer, pSub->interval, pSub, tscTmr, &pSub->pTimer);
+}
+
+
+TAOS_SUB *taos_subscribe(TAOS *taos, const char *sql, TAOS_SUBSCRIBE_CALLBACK fp, void *param, int interval) {
+  STscObj* pObj = (STscObj*)taos;
+  if (pObj == NULL || pObj->signature != pObj) {
+    globalCode = TSDB_CODE_DISCONNECTED;
+    tscError("connection disconnected");
+    return NULL;
+  }
+
+  SSub* pSub = tscCreateSubscription(pObj, sql);
+  if (pSub == NULL) {
+    return NULL;
+  }
+
+  int code = (uint8_t)tsParseSql(pSub->pSql, pObj->acctId, pObj->db, false);
+  if (code != TSDB_CODE_SUCCESS) {
+    taos_unsubscribe(pSub);
+    return NULL;
+  }
+
+// ??? if there's more than one vnode
+  SSqlCmd* pCmd = &pSub->pSql->cmd;
+
+  SMeterMetaInfo *pMeterMetaInfo = tscGetMeterMetaInfo(pCmd, 0);
+  if (UTIL_METER_IS_NOMRAL_METER(pMeterMetaInfo)) {
+    pSub->numOfMeters = 1;
+    pSub->progress = calloc(1, sizeof(SSubscriptionProgress));
+    pSub->progress[0].uid = pMeterMetaInfo->pMeterMeta->uid;
+  } else {
+    SMetricMeta* pMetricMeta = pMeterMetaInfo->pMetricMeta;
+    SVnodeSidList *pVnodeSidList = tscGetVnodeSidList(pMetricMeta, pMeterMetaInfo->vnodeIndex);
+    pSub->numOfMeters = pVnodeSidList->numOfSids;
+    pSub->progress = calloc(pSub->numOfMeters, sizeof(SSubscriptionProgress));
+    for (int32_t i = 0; i < pSub->numOfMeters; ++i) {
+      SMeterSidExtInfo *pMeterInfo = tscGetMeterSidInfo(pVnodeSidList, i);
+      pSub->progress[i].uid = pMeterInfo->uid;
+    }
+    qsort(pSub->progress, pSub->numOfMeters, sizeof(SSubscriptionProgress), tscCompareSubscriptionProgress);
+  }
+
+  // timestamp must in the output column
+  SFieldInfo* pFieldInfo = &pCmd->fieldsInfo;
+  tscFieldInfoSetValue(pFieldInfo, pFieldInfo->numOfOutputCols, TSDB_DATA_TYPE_TIMESTAMP, "_c0", TSDB_KEYSIZE);
+  tscSqlExprInsertEmpty(pCmd, pFieldInfo->numOfOutputCols - 1, TSDB_FUNC_PRJ);
+  tscFieldInfoUpdateVisible(pFieldInfo, pFieldInfo->numOfOutputCols - 1, false);
+  tscFieldInfoCalOffset(pCmd);
+
+  if (fp != NULL) {
+    pSub->fp = fp;
+    pSub->interval = interval;
+    pSub->param = param;
+    taosTmrReset(tscProcessSubscribeTimer, 0, pSub, tscTmr, &pSub->pTimer);
+  }
 
   return pSub;
 }
 
-TAOS_ROW taos_consume(TAOS_SUB *tsub) {
-  SSub *   pSub = (SSub *)tsub;
-  TAOS_ROW row;
-  char     qstr[256];
-
+TAOS_RES *taos_consume(TAOS_SUB *tsub) {
+  SSub *pSub = (SSub *)tsub;
   if (pSub == NULL) return NULL;
-  if (pSub->signature != pSub) return NULL;
 
-  while (1) {
-    if (pSub->result != NULL) {
-      row = taos_fetch_row(pSub->result);
-      if (row != NULL) {
-        pSub->lastKey = *((uint64_t *)row[0]);
-        return row;
-      }
+  SSqlObj* pSql = pSub->pSql;
+  SSqlRes *pRes = &pSql->res;
 
-      taos_free_result(pSub->result);
-      pSub->result = NULL;
-      uint64_t etime = taosGetTimestampMs();
-      int64_t  mseconds = pSub->mseconds - etime + pSub->stime;
-      if (mseconds < 0) mseconds = 0;
-      taosMsleep((int)mseconds);
-    }
+  pRes->numOfRows = 1;
+  pRes->numOfTotal = 0;
+  pRes->qhandle = 0;
+  pSql->thandle = NULL;
 
-    pSub->stime = taosGetTimestampMs();
-
-    sprintf(qstr, "select * from %s where _c0 > %" PRId64 " order by _c0 asc", pSub->name, pSub->lastKey);
-    if (taos_query(pSub->taos, qstr)) {
-      tscTrace("failed to select, reason:%s", taos_errstr(pSub->taos));
-      return NULL;
-    }
-
-    pSub->result = taos_use_result(pSub->taos);
-
-    if (pSub->result == NULL) {
-      tscTrace("failed to get result, reason:%s", taos_errstr(pSub->taos));
-      return NULL;
-    }
+  tscDoQuery(pSql);
+  if (pRes->code != TSDB_CODE_SUCCESS) {
+    return NULL;
   }
-
-  return NULL;
+  return pSql;
 }
 
 void taos_unsubscribe(TAOS_SUB *tsub) {
   SSub *pSub = (SSub *)tsub;
+  if (pSub == NULL || pSub->signature != pSub) return;
 
-  if (pSub == NULL) return;
-  if (pSub->signature != pSub) return;
-
-  taos_close(pSub->taos);
+  if (pSub->pTimer != NULL) {
+    taosTmrStop(pSub->pTimer);
+  }
+  tscFreeSqlObj(pSub->pSql);
+  free(pSub->progress);
+  memset(pSub, 0, sizeof(*pSub));
   free(pSub);
 }
 
 int taos_subfields_count(TAOS_SUB *tsub) {
   SSub *pSub = (SSub *)tsub;
 
-  return pSub->numOfFields;
+  return taos_num_fields(pSub->pSql);
 }
 
 TAOS_FIELD *taos_fetch_subfields(TAOS_SUB *tsub) {
   SSub *pSub = (SSub *)tsub;
 
-  return pSub->fields;
+  return pSub->pSql->cmd.fieldsInfo.pFields;
 }
diff --git a/src/client/src/tscUtil.c b/src/client/src/tscUtil.c
index bc6c73aaae..699c055249 100644
--- a/src/client/src/tscUtil.c
+++ b/src/client/src/tscUtil.c
@@ -819,7 +819,7 @@ void tscFieldInfoSetValFromField(SFieldInfo* pFieldInfo, int32_t index, TAOS_FIE
 }
 
 void tscFieldInfoUpdateVisible(SFieldInfo* pFieldInfo, int32_t index, bool visible) {
-  if (index < 0 || index > pFieldInfo->numOfOutputCols) {
+  if (index < 0 || index >= pFieldInfo->numOfOutputCols) {
     return;
   }
 
diff --git a/src/inc/taos.h b/src/inc/taos.h
index c56d0e86d7..e6eac00a7c 100644
--- a/src/inc/taos.h
+++ b/src/inc/taos.h
@@ -116,11 +116,10 @@ DLL_EXPORT void taos_query_a(TAOS *taos, const char *sql, void (*fp)(void *param
 DLL_EXPORT void taos_fetch_rows_a(TAOS_RES *res, void (*fp)(void *param, TAOS_RES *, int numOfRows), void *param);
 DLL_EXPORT void taos_fetch_row_a(TAOS_RES *res, void (*fp)(void *param, TAOS_RES *, TAOS_ROW row), void *param);
 
-DLL_EXPORT TAOS_SUB *taos_subscribe(const char *host, const char *user, const char *pass, const char *db, const char *table, int64_t time, int mseconds);
-DLL_EXPORT TAOS_ROW taos_consume(TAOS_SUB *tsub);
-DLL_EXPORT void taos_unsubscribe(TAOS_SUB *tsub);
-DLL_EXPORT int taos_subfields_count(TAOS_SUB *tsub);
-DLL_EXPORT TAOS_FIELD *taos_fetch_subfields(TAOS_SUB *tsub);
+typedef void (*TAOS_SUBSCRIBE_CALLBACK)(void *param, TAOS_RES *res, int code);
+DLL_EXPORT TAOS_SUB *taos_subscribe(TAOS *taos, const char *sql, TAOS_SUBSCRIBE_CALLBACK fp, void *param, int interval);
+DLL_EXPORT TAOS_RES *taos_consume(TAOS_SUB *tsub);
+DLL_EXPORT void      taos_unsubscribe(TAOS_SUB *tsub);
 
 DLL_EXPORT TAOS_STREAM *taos_open_stream(TAOS *taos, const char *sql, void (*fp)(void *param, TAOS_RES *, TAOS_ROW row),
                               int64_t stime, void *param, void (*callback)(void *));
diff --git a/src/inc/taosmsg.h b/src/inc/taosmsg.h
index 22b10eaa60..89807f0a19 100644
--- a/src/inc/taosmsg.h
+++ b/src/inc/taosmsg.h
@@ -490,6 +490,7 @@ typedef struct SColumnInfo {
 typedef struct SMeterSidExtInfo {
   int32_t sid;
   int64_t uid;
+  TSKEY   skey;   // start key for subscription
   char    tags[];
 } SMeterSidExtInfo;
 
@@ -572,6 +573,7 @@ typedef struct {
   int16_t precision;
   int64_t offset;  // updated offset value for multi-vnode projection query
   int64_t useconds;
+  int64_t uid;
   char    data[];
 } SRetrieveMeterRsp;
 
diff --git a/src/system/detail/src/vnodeShell.c b/src/system/detail/src/vnodeShell.c
index ce1cabe141..5177afc13a 100644
--- a/src/system/detail/src/vnodeShell.c
+++ b/src/system/detail/src/vnodeShell.c
@@ -456,6 +456,7 @@ void vnodeExecuteRetrieveReq(SSchedMsg *pSched) {
   if (code == TSDB_CODE_SUCCESS) {
     pRsp->offset = htobe64(vnodeGetOffsetVal((void*)pRetrieve->qhandle));
     pRsp->useconds = htobe64(((SQInfo *)(pRetrieve->qhandle))->useconds);
+    pRsp->uid = ((SQInfo *)(pRetrieve->qhandle))->pObj->uid;
   } else {
     pRsp->offset = 0;
     pRsp->useconds = 0;
diff --git a/tests/examples/c/subscribe.c b/tests/examples/c/subscribe.c
index 219fa133e0..f09018b1d2 100644
--- a/tests/examples/c/subscribe.c
+++ b/tests/examples/c/subscribe.c
@@ -1,18 +1,3 @@
-/*
- * Copyright (c) 2019 TAOS Data, Inc. <jhtao@taosdata.com>
- *
- * This program is free software: you can use, redistribute, and/or modify
- * it under the terms of the GNU Affero General Public License, version 3
- * or later ("AGPL"), as published by the Free Software Foundation.
- *
- * This program is distributed in the hope that it will be useful, but WITHOUT
- * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
- * FITNESS FOR A PARTICULAR PURPOSE.
- *
- * You should have received a copy of the GNU Affero General Public License
- * along with this program. If not, see <http://www.gnu.org/licenses/>.
- */
-
 // sample code for TDengine subscribe/consume API
 // to compile: gcc -o subscribe subscribe.c -ltaos
 
@@ -21,38 +6,38 @@
 #include <string.h>
 #include <taos.h>  // include TDengine header file
 
-int main(int argc, char *argv[]) 
-{
-  TAOS_SUB   *tsub;
-  TAOS_ROW    row;
-  char        dbname[64], table[64];
-  char        temp[256];
+int main(int argc, char *argv[]) {
+  // init TAOS
+  taos_init();
 
-  if ( argc == 1 ) {
-    printf("usage: %s server-ip db-name table-name \n", argv[0]);
-    exit(0);
-  } 
-
-  if ( argc >= 2 ) strcpy(dbname, argv[2]);
-  if ( argc >= 3 ) strcpy(table, argv[3]);
-
-  tsub = taos_subscribe(argv[1], "root", "taosdata", dbname, table, 0, 1000);
-  if ( tsub == NULL ) {
-    printf("failed to connet to db:%s\n", dbname);
+  TAOS* taos = taos_connect(argv[1], "root", "taosdata", "test", 0);
+  if (taos == NULL) {
+    printf("failed to connect to db, reason:%s\n", taos_errstr(taos));
     exit(1);
   }
 
-  TAOS_FIELD *fields = taos_fetch_subfields(tsub);
-  int fcount = taos_subfields_count(tsub);
+  TAOS_SUB* tsub = taos_subscribe(taos, "select * from meters;", NULL, NULL, 0);
+  if ( tsub == NULL ) {
+    printf("failed to create subscription.\n");
+    exit(0);
+  } 
 
-  printf("start to retrieve data\n");
-  printf("please use other taos client, insert rows into %s.%s\n", dbname, table);
-  while ( 1 ) {
-    row = taos_consume(tsub);
-    if ( row == NULL ) break;
+  for( int i = 0; i < 3; i++ ) {
+    TAOS_RES* res = taos_consume(tsub);
+    TAOS_ROW    row;
+    int         rows = 0;
+    int         num_fields = taos_subfields_count(tsub);
+    TAOS_FIELD *fields = taos_fetch_fields(res);
+    char        temp[256];
 
-    taos_print_row(temp, row, fields, fcount);
-    printf("%s\n", temp);
+    // fetch the records row by row
+    while ((row = taos_fetch_row(res))) {
+      rows++;
+      taos_print_row(temp, row, fields, num_fields);
+      printf("%s\n", temp);
+    }
+
+    printf("\n");
   }
 
   taos_unsubscribe(tsub);

From 192ad4df354477eb3fe5ba7122dcd6cc074752f5 Mon Sep 17 00:00:00 2001
From: localvar <localvar@hotmail.com>
Date: Thu, 26 Dec 2019 17:14:30 +0800
Subject: [PATCH 02/35] return last key of each meter to client

---
 src/client/src/tscServer.c                | 21 ++++++++--
 src/client/src/tscSql.c                   | 47 +++++++++++------------
 src/client/src/tscSub.c                   |  3 +-
 src/inc/taosmsg.h                         |  3 +-
 src/system/detail/src/vnodeQueryProcess.c |  3 ++
 src/system/detail/src/vnodeRead.c         | 14 ++++---
 src/system/detail/src/vnodeShell.c        | 22 +++++++++--
 7 files changed, 74 insertions(+), 39 deletions(-)

diff --git a/src/client/src/tscServer.c b/src/client/src/tscServer.c
index 9a88ee9fc4..1aa56169df 100644
--- a/src/client/src/tscServer.c
+++ b/src/client/src/tscServer.c
@@ -1531,7 +1531,7 @@ static char* doSerializeTableInfo(SSqlObj* pSql, int32_t numOfMeters, int32_t vn
     SMeterSidExtInfo *pMeterInfo = (SMeterSidExtInfo *)pMsg;
     pMeterInfo->sid = htonl(pMeterMeta->sid);
     pMeterInfo->uid = htobe64(pMeterMeta->uid);
-    pMeterInfo->skey = tscGetSubscriptionProgress(pSql, pMeterMeta->uid);
+    pMeterInfo->key = htobe64(tscGetSubscriptionProgress(pSql, pMeterMeta->uid));
     pMsg += sizeof(SMeterSidExtInfo);
   } else {
     SVnodeSidList *pVnodeSidList = tscGetVnodeSidList(pMetricMeta, pMeterMetaInfo->vnodeIndex);
@@ -1542,7 +1542,7 @@ static char* doSerializeTableInfo(SSqlObj* pSql, int32_t numOfMeters, int32_t vn
       
       pMeterInfo->sid = htonl(pQueryMeterInfo->sid);
       pMeterInfo->uid = htobe64(pQueryMeterInfo->uid);
-      pMeterInfo->skey = tscGetSubscriptionProgress(pSql, pMeterMeta->uid);
+      pMeterInfo->key = htobe64(tscGetSubscriptionProgress(pSql, pQueryMeterInfo->uid));
       
       pMsg += sizeof(SMeterSidExtInfo);
       
@@ -3526,6 +3526,7 @@ int tscProcessQueryRsp(SSqlObj *pSql) {
   return 0;
 }
 
+void tscUpdateSubscriptionProgress(SSqlObj* pSql, int64_t uid, TSKEY ts);
 int tscProcessRetrieveRspFromVnode(SSqlObj *pSql) {
   SSqlRes *pRes = &pSql->res;
   SSqlCmd *pCmd = &pSql->cmd;
@@ -3536,11 +3537,25 @@ int tscProcessRetrieveRspFromVnode(SSqlObj *pSql) {
   pRes->numOfRows = htonl(pRetrieve->numOfRows);
   pRes->precision = htons(pRetrieve->precision);
   pRes->offset = htobe64(pRetrieve->offset);
-  pRes->uid = pRetrieve->uid;
   pRes->useconds = htobe64(pRetrieve->useconds);
   pRes->data = pRetrieve->data;
 
   tscSetResultPointer(pCmd, pRes);
+
+  TAOS_FIELD *pField = tscFieldInfoGetField(pCmd, pCmd->fieldsInfo.numOfOutputCols - 1);
+  int16_t     offset = tscFieldInfoGetOffset(pCmd, pCmd->fieldsInfo.numOfOutputCols - 1);
+  char* p = pRes->data + (pField->bytes + offset) * pRes->numOfRows;
+
+  int32_t numOfMeters = htonl(*(int32_t*)p);
+  p += sizeof(int32_t);
+  for (int i = 0; i < numOfMeters; i++) {
+    int64_t uid = htobe64(*(int64_t*)p);
+    p += sizeof(int64_t);
+    TSKEY key = htobe64(*(TSKEY*)p);
+    p += sizeof(TSKEY);
+    tscUpdateSubscriptionProgress(pSql, uid, key);
+  }
+
   pRes->row = 0;
 
   /**
diff --git a/src/client/src/tscSql.c b/src/client/src/tscSql.c
index 404c3f947b..9c812d4187 100644
--- a/src/client/src/tscSql.c
+++ b/src/client/src/tscSql.c
@@ -627,11 +627,6 @@ TAOS_ROW taos_fetch_row(TAOS_RES *res) {
       rows = taos_fetch_row_impl(res);
     }
 
-    if (rows != NULL && pSql->pSubscription != NULL) {
-      TSKEY ts = *(TSKEY*)rows[pCmd->fieldsInfo.numOfOutputCols - 1];
-      tscUpdateSubscriptionProgress(pMeterMetaInfo->pMeterMeta->uid, ts);
-    }
-
     // check!!!
     if (rows != NULL || pMeterMetaInfo->vnodeIndex >= pMeterMetaInfo->pMetricMeta->numOfVnodes) {
       break;
@@ -866,61 +861,63 @@ void taos_stop_query(TAOS_RES *res) {
 int taos_print_row(char *str, TAOS_ROW row, TAOS_FIELD *fields, int num_fields) {
   int len = 0;
   for (int i = 0; i < num_fields; ++i) {
+    if (i > 0) {
+      str[len++] = ' ';
+    }
+
     if (row[i] == NULL) {
-      len += sprintf(str + len, "%s ", TSDB_DATA_NULL_STR);
+      len += sprintf(str + len, "%s", TSDB_DATA_NULL_STR);
       continue;
     }
 
     switch (fields[i].type) {
       case TSDB_DATA_TYPE_TINYINT:
-        len += sprintf(str + len, "%d ", *((char *)row[i]));
+        len += sprintf(str + len, "%d", *((char *)row[i]));
         break;
 
       case TSDB_DATA_TYPE_SMALLINT:
-        len += sprintf(str + len, "%d ", *((short *)row[i]));
+        len += sprintf(str + len, "%d", *((short *)row[i]));
         break;
 
       case TSDB_DATA_TYPE_INT:
-        len += sprintf(str + len, "%d ", *((int *)row[i]));
+        len += sprintf(str + len, "%d", *((int *)row[i]));
         break;
 
       case TSDB_DATA_TYPE_BIGINT:
-        len += sprintf(str + len, "%" PRId64 " ", *((int64_t *)row[i]));
+        len += sprintf(str + len, "%" PRId64, *((int64_t *)row[i]));
         break;
 
       case TSDB_DATA_TYPE_FLOAT: {
         float fv = 0;
         fv = GET_FLOAT_VAL(row[i]);
-        len += sprintf(str + len, "%f ", fv);
+        len += sprintf(str + len, "%f", fv);
       }
         break;
 
       case TSDB_DATA_TYPE_DOUBLE:{
         double dv = 0;
         dv = GET_DOUBLE_VAL(row[i]);
-        len += sprintf(str + len, "%lf ", dv);
+        len += sprintf(str + len, "%lf", dv);
       }
-        break;
 
       case TSDB_DATA_TYPE_BINARY:
       case TSDB_DATA_TYPE_NCHAR: {
-        /* limit the max length of string to no greater than the maximum length,
-         * in case of not null-terminated string */
-        size_t xlen = strlen(row[i]);
-        size_t trueLen = MIN(xlen, fields[i].bytes);
-
-        memcpy(str + len, (char *)row[i], trueLen);
-
-        str[len + trueLen] = ' ';
-        len += (trueLen + 1);
-      } break;
+          size_t xlen = 0;
+          for (xlen = 0; xlen <= fields[i].bytes; xlen++) {
+            char c = ((char*)row[i])[xlen];
+            if (c == 0) break;
+            str[len++] = c;
+          }
+          str[len] = 0;
+        }
+        break;
 
       case TSDB_DATA_TYPE_TIMESTAMP:
-        len += sprintf(str + len, "%" PRId64 " ", *((int64_t *)row[i]));
+        len += sprintf(str + len, "%" PRId64, *((int64_t *)row[i]));
         break;
 
       case TSDB_DATA_TYPE_BOOL:
-        len += sprintf(str + len, "%d ", *((int8_t *)row[i]));
+        len += sprintf(str + len, "%d", *((int8_t *)row[i]));
       default:
         break;
     }
diff --git a/src/client/src/tscSub.c b/src/client/src/tscSub.c
index af3a576377..a55e889c1c 100644
--- a/src/client/src/tscSub.c
+++ b/src/client/src/tscSub.c
@@ -80,7 +80,7 @@ void tscUpdateSubscriptionProgress(SSqlObj* pSql, int64_t uid, TSKEY ts) {
     else if (p->uid < uid)
       s = m + 1;
     else {
-      p->key = ts + 1;
+      if (ts >= p->key) p->key = ts + 1;
       break;
     }
   }
@@ -219,6 +219,7 @@ TAOS_RES *taos_consume(TAOS_SUB *tsub) {
   pRes->numOfTotal = 0;
   pRes->qhandle = 0;
   pSql->thandle = NULL;
+  pSql->cmd.command = TSDB_SQL_SELECT;
 
   tscDoQuery(pSql);
   if (pRes->code != TSDB_CODE_SUCCESS) {
diff --git a/src/inc/taosmsg.h b/src/inc/taosmsg.h
index 89807f0a19..9151851330 100644
--- a/src/inc/taosmsg.h
+++ b/src/inc/taosmsg.h
@@ -490,7 +490,7 @@ typedef struct SColumnInfo {
 typedef struct SMeterSidExtInfo {
   int32_t sid;
   int64_t uid;
-  TSKEY   skey;   // start key for subscription
+  TSKEY   key;   // key for subscription
   char    tags[];
 } SMeterSidExtInfo;
 
@@ -573,7 +573,6 @@ typedef struct {
   int16_t precision;
   int64_t offset;  // updated offset value for multi-vnode projection query
   int64_t useconds;
-  int64_t uid;
   char    data[];
 } SRetrieveMeterRsp;
 
diff --git a/src/system/detail/src/vnodeQueryProcess.c b/src/system/detail/src/vnodeQueryProcess.c
index c69b27537e..2e59789b27 100644
--- a/src/system/detail/src/vnodeQueryProcess.c
+++ b/src/system/detail/src/vnodeQueryProcess.c
@@ -750,6 +750,8 @@ static void vnodeMultiMeterMultiOutputProcessor(SQInfo *pQInfo) {
         pQuery->ekey = pSupporter->rawEKey;
         pSupporter->meterIdx++;
 
+        pQInfo->pMeterQuerySupporter->pMeterSidExtInfo[k]->key = pQuery->lastKey;
+
         // if the buffer is full or group by each table, we need to jump out of the loop
         if (Q_STATUS_EQUAL(pQuery->over, QUERY_RESBUF_FULL) ||
             isGroupbyEachTable(pQuery->pGroupbyExpr, pSupporter->pSidSet)) {
@@ -765,6 +767,7 @@ static void vnodeMultiMeterMultiOutputProcessor(SQInfo *pQInfo) {
           assert(!Q_STATUS_EQUAL(pQuery->over, QUERY_RESBUF_FULL));
           continue;
         } else {
+          pQInfo->pMeterQuerySupporter->pMeterSidExtInfo[k]->key = pQuery->lastKey;
           // buffer is full, wait for the next round to retrieve data from current meter
           assert(Q_STATUS_EQUAL(pQuery->over, QUERY_RESBUF_FULL));
           break;
diff --git a/src/system/detail/src/vnodeRead.c b/src/system/detail/src/vnodeRead.c
index bbd3e9465c..2a913665cd 100644
--- a/src/system/detail/src/vnodeRead.c
+++ b/src/system/detail/src/vnodeRead.c
@@ -753,7 +753,6 @@ void *vnodeQueryOnMultiMeters(SMeterObj **pMetersObj, SSqlGroupbyExpr *pGroupbyE
     taosAddIntHash(pSupporter->pMeterObj, pMetersObj[i]->sid, (char *)&pMetersObj[i]);
   }
 
-  pSupporter->pMeterSidExtInfo = (SMeterSidExtInfo **)pQueryMsg->pSidExtInfo;
   int32_t sidElemLen = pQueryMsg->tagLength + sizeof(SMeterSidExtInfo);
 
   int32_t size = POINTER_BYTES * pQueryMsg->numOfSids + sidElemLen * pQueryMsg->numOfSids;
@@ -767,12 +766,16 @@ void *vnodeQueryOnMultiMeters(SMeterObj **pMetersObj, SSqlGroupbyExpr *pGroupbyE
   char *px = ((char *)pSupporter->pMeterSidExtInfo) + POINTER_BYTES * pQueryMsg->numOfSids;
 
   for (int32_t i = 0; i < pQueryMsg->numOfSids; ++i) {
-    pSupporter->pMeterSidExtInfo[i] = (SMeterSidExtInfo *)px;
-    pSupporter->pMeterSidExtInfo[i]->sid = ((SMeterSidExtInfo **)pQueryMsg->pSidExtInfo)[i]->sid;
+    SMeterSidExtInfo* pSrc = ((SMeterSidExtInfo **)pQueryMsg->pSidExtInfo)[i];
+    SMeterSidExtInfo* pDst = (SMeterSidExtInfo *)px;
+
+    pSupporter->pMeterSidExtInfo[i] = pDst;
+    pDst->sid = pSrc->sid;
+    pDst->uid = pSrc->uid;
+    pDst->key = pSrc->key;
 
     if (pQueryMsg->tagLength > 0) {
-      memcpy(pSupporter->pMeterSidExtInfo[i]->tags, ((SMeterSidExtInfo **)pQueryMsg->pSidExtInfo)[i]->tags,
-             pQueryMsg->tagLength);
+      memcpy(pDst->tags, pSrc->tags, pQueryMsg->tagLength);
     }
     px += sidElemLen;
   }
@@ -1107,6 +1110,7 @@ int32_t vnodeConvertQueryMeterMsg(SQueryMeterMsg *pQueryMsg) {
     pSids[j] = (SMeterSidExtInfo *)((char *)pSids[j - 1] + sizeof(SMeterSidExtInfo) + pQueryMsg->tagLength);
     pSids[j]->sid = htonl(pSids[j]->sid);
     pSids[j]->uid = htobe64(pSids[j]->uid);
+    pSids[j]->key = htobe64(pSids[j]->key);
   }
 
   pMsg = (char *)pSids[pQueryMsg->numOfSids - 1];
diff --git a/src/system/detail/src/vnodeShell.c b/src/system/detail/src/vnodeShell.c
index 5177afc13a..2c8fe35cca 100644
--- a/src/system/detail/src/vnodeShell.c
+++ b/src/system/detail/src/vnodeShell.c
@@ -412,6 +412,7 @@ void vnodeExecuteRetrieveReq(SSchedMsg *pSched) {
 
   int code = 0;
   pRetrieve = (SRetrieveMeterMsg *)pMsg;
+  SQInfo* pQInfo = (SQInfo*)pRetrieve->qhandle;
   pRetrieve->free = htons(pRetrieve->free);
 
   if ((pRetrieve->free & TSDB_QUERY_TYPE_FREE_RESOURCE) != TSDB_QUERY_TYPE_FREE_RESOURCE) {
@@ -438,7 +439,11 @@ void vnodeExecuteRetrieveReq(SSchedMsg *pSched) {
     size = vnodeGetResultSize((void *)(pRetrieve->qhandle), &numOfRows);
   }
 
-  pStart = taosBuildRspMsgWithSize(pObj->thandle, TSDB_MSG_TYPE_RETRIEVE_RSP, size + 100);
+  // buffer size for progress information, including meter count,
+  // and for each meter, including 'uid' and 'TSKEY'.
+  int progressSize = pQInfo->pMeterQuerySupporter->numOfMeters * (sizeof(int64_t) + sizeof(TSKEY)) + sizeof(int32_t);
+
+  pStart = taosBuildRspMsgWithSize(pObj->thandle, TSDB_MSG_TYPE_RETRIEVE_RSP, progressSize + size + 100);
   if (pStart == NULL) {
     taosSendSimpleRsp(pObj->thandle, TSDB_MSG_TYPE_RETRIEVE_RSP, TSDB_CODE_SERV_OUT_OF_MEMORY);
     goto _exit;
@@ -456,7 +461,6 @@ void vnodeExecuteRetrieveReq(SSchedMsg *pSched) {
   if (code == TSDB_CODE_SUCCESS) {
     pRsp->offset = htobe64(vnodeGetOffsetVal((void*)pRetrieve->qhandle));
     pRsp->useconds = htobe64(((SQInfo *)(pRetrieve->qhandle))->useconds);
-    pRsp->uid = ((SQInfo *)(pRetrieve->qhandle))->pObj->uid;
   } else {
     pRsp->offset = 0;
     pRsp->useconds = 0;
@@ -469,11 +473,23 @@ void vnodeExecuteRetrieveReq(SSchedMsg *pSched) {
   }
 
   pMsg += size;
+
+  // write the progress information of each meter to response
+  // this is required by subscriptions
+  *((int32_t*)pMsg) = htonl(pQInfo->pMeterQuerySupporter->numOfMeters);
+  pMsg += sizeof(int32_t);
+  for (int32_t i = 0; i < pQInfo->pMeterQuerySupporter->numOfMeters; i++) {
+    *((int64_t*)pMsg) = htobe64(pQInfo->pMeterQuerySupporter->pMeterSidExtInfo[i]->uid);
+    pMsg += sizeof(int64_t);
+    *((TSKEY*)pMsg) = htobe64(pQInfo->pMeterQuerySupporter->pMeterSidExtInfo[i]->key);
+    pMsg += sizeof(TSKEY);
+  }
+
   msgLen = pMsg - pStart;
 
   assert(code != TSDB_CODE_ACTION_IN_PROGRESS);
   
-  if (numOfRows == 0 && (pRetrieve->qhandle == (uint64_t)pObj->qhandle) && (code != TSDB_CODE_ACTION_IN_PROGRESS)) {
+  if (numOfRows == 0 && (pRetrieve->qhandle == (uint64_t)pObj->qhandle) && (code != TSDB_CODE_ACTION_IN_PROGRESS) && pRetrieve->qhandle != NULL) {
     dTrace("QInfo:%p %s free qhandle code:%d", pObj->qhandle, __FUNCTION__, code);
     vnodeDecRefCount(pObj->qhandle);
     pObj->qhandle = NULL;

From 804b581269800faf842e8dfbc922904d7b4a825c Mon Sep 17 00:00:00 2001
From: localvar <localvar@hotmail.com>
Date: Fri, 27 Dec 2019 17:15:20 +0800
Subject: [PATCH 03/35] TBASE-917: update subscription example

---
 tests/examples/c/makefile    | 25 ++++++------
 tests/examples/c/subscribe.c | 74 +++++++++++++++++++++++++++---------
 2 files changed, 69 insertions(+), 30 deletions(-)

diff --git a/tests/examples/c/makefile b/tests/examples/c/makefile
index ac8ff21aaf..d68a734e95 100644
--- a/tests/examples/c/makefile
+++ b/tests/examples/c/makefile
@@ -3,21 +3,22 @@
 
 ROOT=./
 TARGET=exe
-LFLAGS = '-Wl,-rpath,/usr/local/taos/driver' -ltaos -lpthread -lm -lrt
-CFLAGS = -O3 -g -Wall -Wno-deprecated -fPIC -Wno-unused-result -Wconversion -Wno-char-subscripts -D_REENTRANT -Wno-format -D_REENTRANT -DLINUX -msse4.2 -Wno-unused-function -D_M_X64 -std=gnu99
+LFLAGS = '-Wl,-rpath,/usr/local/taos/driver/' -ltaos -lpthread -lm -lrt
+CFLAGS = -O3 -g -Wall -Wno-deprecated -fPIC -Wno-unused-result -Wconversion -Wno-char-subscripts -D_REENTRANT -Wno-format -D_REENTRANT -DLINUX -msse4.2 -Wno-unused-function -D_M_X64 \
+	-I/usr/local/taos/include -std=gnu99
 
 all: $(TARGET)
 
 exe:
-	gcc $(CFLAGS) ./asyncdemo.c -o $(ROOT)/asyncdemo $(LFLAGS)
-	gcc $(CFLAGS) ./demo.c -o $(ROOT)/demo $(LFLAGS)
-	gcc $(CFLAGS) ./stream.c -o $(ROOT)/stream $(LFLAGS)
-	gcc $(CFLAGS) ./subscribe.c -o $(ROOT)/subscribe $(LFLAGS)
+gcc $(CFLAGS) ./asyncdemo.c -o $(ROOT)/asyncdemo $(LFLAGS)
+gcc $(CFLAGS) ./demo.c -o $(ROOT)/demo $(LFLAGS)
+gcc $(CFLAGS) ./prepare.c -o $(ROOT)/prepare $(LFLAGS)
+gcc $(CFLAGS) ./stream.c -o $(ROOT)/stream $(LFLAGS)
+	gcc $(CFLAGS) ./subscribe.c -o $(ROOT)subscribe $(LFLAGS)
 
 clean:
-	rm $(ROOT)asyncdemo
-	rm $(ROOT)demo
-	rm $(ROOT)stream
-	rm $(ROOT)subscribe
-	
-	
\ No newline at end of file
+	rm $(ROOT)/asyncdemo
+	rm $(ROOT)/demo
+	rm $(ROOT)/prepare
+	rm $(ROOT)/stream
+	rm $(ROOT)/subscribe
diff --git a/tests/examples/c/subscribe.c b/tests/examples/c/subscribe.c
index f09018b1d2..b35dca772f 100644
--- a/tests/examples/c/subscribe.c
+++ b/tests/examples/c/subscribe.c
@@ -6,38 +6,76 @@
 #include <string.h>
 #include <taos.h>  // include TDengine header file
 
+
+void print_result(TAOS_RES* res) {
+  TAOS_ROW    row;
+  int         num_fields = taos_num_fields(res);
+  TAOS_FIELD* fields = taos_fetch_fields(res);
+
+  while ((row = taos_fetch_row(res))) {
+    char temp[256];
+    taos_print_row(temp, row, fields, num_fields);
+    puts(temp);
+  }
+}
+
+void subscribe_callback(TAOS_SUB* tsub, TAOS_RES *res, void* param, int code) {
+  print_result(res);
+}
+
+
 int main(int argc, char *argv[]) {
+  const char* host = "127.0.0.1";
+  const char* user = "root";
+  const char* passwd = "taosdata";
+  int async = 1;
+  TAOS_SUB* tsub = NULL;
+
+  for (int i = 1; i < argc; i++) {
+    if (strncmp(argv[i], "-h=", 3) == 0) {
+      host = argv[i] + 3;
+      continue;
+    }
+    if (strncmp(argv[i], "-u=", 3) == 0) {
+      user = argv[i] + 3;
+      continue;
+    }
+    if (strncmp(argv[i], "-p=", 3) == 0) {
+      passwd = argv[i] + 3;
+      continue;
+    }
+    if (strncmp(argv[i], "-m=", 3) == 0) {
+      async = strcmp(argv[i] + 3, "sync");
+      continue;
+    }
+  }
+
   // init TAOS
   taos_init();
 
-  TAOS* taos = taos_connect(argv[1], "root", "taosdata", "test", 0);
+  TAOS* taos = taos_connect(host, user, passwd, "test", 0);
   if (taos == NULL) {
     printf("failed to connect to db, reason:%s\n", taos_errstr(taos));
     exit(1);
   }
 
-  TAOS_SUB* tsub = taos_subscribe(taos, "select * from meters;", NULL, NULL, 0);
-  if ( tsub == NULL ) {
+  if (async) {
+    tsub = taos_subscribe(taos, "select * from meters;", subscribe_callback, NULL, 1000);
+  } else {
+    tsub = taos_subscribe(taos, "select * from meters;", NULL, NULL, 0);
+  }
+
+  if (tsub == NULL) {
     printf("failed to create subscription.\n");
     exit(0);
   } 
 
-  for( int i = 0; i < 3; i++ ) {
+  if (async) {
+    getchar();
+  } else while(1) {
     TAOS_RES* res = taos_consume(tsub);
-    TAOS_ROW    row;
-    int         rows = 0;
-    int         num_fields = taos_subfields_count(tsub);
-    TAOS_FIELD *fields = taos_fetch_fields(res);
-    char        temp[256];
-
-    // fetch the records row by row
-    while ((row = taos_fetch_row(res))) {
-      rows++;
-      taos_print_row(temp, row, fields, num_fields);
-      printf("%s\n", temp);
-    }
-
-    printf("\n");
+    print_result(res);
+    getchar();
   }
 
   taos_unsubscribe(tsub);

From 3537de849a8056d021655528b4469d2a1ecb5ea2 Mon Sep 17 00:00:00 2001
From: localvar <localvar@hotmail.com>
Date: Fri, 27 Dec 2019 17:32:53 +0800
Subject: [PATCH 04/35] update query process

---
 src/client/src/tscServer.c                |  3 ++-
 src/client/src/tscSub.c                   | 16 ++--------------
 src/inc/taos.h                            |  2 +-
 src/system/detail/src/vnodeQueryProcess.c |  9 +++++++++
 4 files changed, 14 insertions(+), 16 deletions(-)

diff --git a/src/client/src/tscServer.c b/src/client/src/tscServer.c
index 1aa56169df..ca96103593 100644
--- a/src/client/src/tscServer.c
+++ b/src/client/src/tscServer.c
@@ -46,6 +46,8 @@ int (*tscProcessMsgRsp[TSDB_SQL_MAX])(SSqlObj *pSql);
 void (*tscUpdateVnodeMsg[TSDB_SQL_MAX])(SSqlObj *pSql, char *buf);
 void tscProcessActivityTimer(void *handle, void *tmrId);
 int tscKeepConn[TSDB_SQL_MAX] = {0};
+TSKEY tscGetSubscriptionProgress(SSqlObj* pSql, int64_t uid);
+void tscUpdateSubscriptionProgress(SSqlObj* pSql, int64_t uid, TSKEY ts);
 
 static int32_t minMsgSize() { return tsRpcHeadSize + sizeof(STaosDigest); }
 
@@ -3526,7 +3528,6 @@ int tscProcessQueryRsp(SSqlObj *pSql) {
   return 0;
 }
 
-void tscUpdateSubscriptionProgress(SSqlObj* pSql, int64_t uid, TSKEY ts);
 int tscProcessRetrieveRspFromVnode(SSqlObj *pSql) {
   SSqlRes *pRes = &pSql->res;
   SSqlCmd *pCmd = &pSql->cmd;
diff --git a/src/client/src/tscSub.c b/src/client/src/tscSub.c
index a55e889c1c..5a2ae4ee4e 100644
--- a/src/client/src/tscSub.c
+++ b/src/client/src/tscSub.c
@@ -144,8 +144,8 @@ static void tscProcessSubscribeTimer(void *handle, void *tmrId) {
 
   TAOS_RES* res = taos_consume(pSub);
   if (res != NULL) {
-    pSub->fp(pSub->param, res, 0);
-    taos_free_result(res);
+    pSub->fp(pSub, res, pSub->param, 0);
+    // TODO: memory leak
   }
 
   taosTmrReset(tscProcessSubscribeTimer, pSub->interval, pSub, tscTmr, &pSub->pTimer);
@@ -240,15 +240,3 @@ void taos_unsubscribe(TAOS_SUB *tsub) {
   memset(pSub, 0, sizeof(*pSub));
   free(pSub);
 }
-
-int taos_subfields_count(TAOS_SUB *tsub) {
-  SSub *pSub = (SSub *)tsub;
-
-  return taos_num_fields(pSub->pSql);
-}
-
-TAOS_FIELD *taos_fetch_subfields(TAOS_SUB *tsub) {
-  SSub *pSub = (SSub *)tsub;
-
-  return pSub->pSql->cmd.fieldsInfo.pFields;
-}
diff --git a/src/inc/taos.h b/src/inc/taos.h
index e6eac00a7c..aa2ed02f9b 100644
--- a/src/inc/taos.h
+++ b/src/inc/taos.h
@@ -116,7 +116,7 @@ DLL_EXPORT void taos_query_a(TAOS *taos, const char *sql, void (*fp)(void *param
 DLL_EXPORT void taos_fetch_rows_a(TAOS_RES *res, void (*fp)(void *param, TAOS_RES *, int numOfRows), void *param);
 DLL_EXPORT void taos_fetch_row_a(TAOS_RES *res, void (*fp)(void *param, TAOS_RES *, TAOS_ROW row), void *param);
 
-typedef void (*TAOS_SUBSCRIBE_CALLBACK)(void *param, TAOS_RES *res, int code);
+typedef void (*TAOS_SUBSCRIBE_CALLBACK)(TAOS_SUB* tsub, TAOS_RES *res, void* param, int code);
 DLL_EXPORT TAOS_SUB *taos_subscribe(TAOS *taos, const char *sql, TAOS_SUBSCRIBE_CALLBACK fp, void *param, int interval);
 DLL_EXPORT TAOS_RES *taos_consume(TAOS_SUB *tsub);
 DLL_EXPORT void      taos_unsubscribe(TAOS_SUB *tsub);
diff --git a/src/system/detail/src/vnodeQueryProcess.c b/src/system/detail/src/vnodeQueryProcess.c
index 2e59789b27..ae73ba5249 100644
--- a/src/system/detail/src/vnodeQueryProcess.c
+++ b/src/system/detail/src/vnodeQueryProcess.c
@@ -682,10 +682,19 @@ static void vnodeMultiMeterMultiOutputProcessor(SQInfo *pQInfo) {
     while (pSupporter->meterIdx < pSupporter->numOfMeters) {
       int32_t k = pSupporter->meterIdx;
 
+pQInfo->killed = 0;
+/*
       if (isQueryKilled(pQuery)) {
         setQueryStatus(pQuery, QUERY_NO_DATA_TO_CHECK);
         return;
       }
+*/
+
+      TSKEY skey = pQInfo->pMeterQuerySupporter->pMeterSidExtInfo[k]->key;
+      if (skey > 0) {
+        pQuery->skey = skey;
+        // pQuery->lastKey = ???;
+      }
 
       bool dataInDisk = true;
       bool dataInCache = true;

From 44536fdcf746a9d32ce79fa104d645e3da3e1e98 Mon Sep 17 00:00:00 2001
From: localvar <localvar@hotmail.com>
Date: Tue, 31 Dec 2019 17:53:16 +0800
Subject: [PATCH 05/35] TBASE-1427

---
 src/client/src/tscServer.c         | 24 ++++----
 src/client/src/tscSub.c            | 90 ++++++++++++++++++++----------
 src/system/detail/src/vnodeRead.c  |  1 +
 src/system/detail/src/vnodeShell.c | 20 ++++---
 4 files changed, 86 insertions(+), 49 deletions(-)

diff --git a/src/client/src/tscServer.c b/src/client/src/tscServer.c
index ca96103593..03b66a1996 100644
--- a/src/client/src/tscServer.c
+++ b/src/client/src/tscServer.c
@@ -3543,18 +3543,20 @@ int tscProcessRetrieveRspFromVnode(SSqlObj *pSql) {
 
   tscSetResultPointer(pCmd, pRes);
 
-  TAOS_FIELD *pField = tscFieldInfoGetField(pCmd, pCmd->fieldsInfo.numOfOutputCols - 1);
-  int16_t     offset = tscFieldInfoGetOffset(pCmd, pCmd->fieldsInfo.numOfOutputCols - 1);
-  char* p = pRes->data + (pField->bytes + offset) * pRes->numOfRows;
+  if (pSql->pSubscription != NULL) {
+    TAOS_FIELD *pField = tscFieldInfoGetField(pCmd, pCmd->fieldsInfo.numOfOutputCols - 1);
+    int16_t     offset = tscFieldInfoGetOffset(pCmd, pCmd->fieldsInfo.numOfOutputCols - 1);
+    char* p = pRes->data + (pField->bytes + offset) * pRes->numOfRows;
 
-  int32_t numOfMeters = htonl(*(int32_t*)p);
-  p += sizeof(int32_t);
-  for (int i = 0; i < numOfMeters; i++) {
-    int64_t uid = htobe64(*(int64_t*)p);
-    p += sizeof(int64_t);
-    TSKEY key = htobe64(*(TSKEY*)p);
-    p += sizeof(TSKEY);
-    tscUpdateSubscriptionProgress(pSql, uid, key);
+    int32_t numOfMeters = htonl(*(int32_t*)p);
+    p += sizeof(int32_t);
+    for (int i = 0; i < numOfMeters; i++) {
+      int64_t uid = htobe64(*(int64_t*)p);
+      p += sizeof(int64_t);
+      TSKEY key = htobe64(*(TSKEY*)p);
+      p += sizeof(TSKEY);
+      tscUpdateSubscriptionProgress(pSql, uid, key);
+    }
   }
 
   pRes->row = 0;
diff --git a/src/client/src/tscSub.c b/src/client/src/tscSub.c
index 5a2ae4ee4e..079c7441ce 100644
--- a/src/client/src/tscSub.c
+++ b/src/client/src/tscSub.c
@@ -32,6 +32,7 @@ typedef struct SSubscriptionProgress {
 } SSubscriptionProgress;
 
 typedef struct SSub {
+  int64_t                 lastSyncTime;
   void *                  signature;
   TAOS *                  taos;
   void *                  pTimer;
@@ -152,6 +153,57 @@ static void tscProcessSubscribeTimer(void *handle, void *tmrId) {
 }
 
 
+bool tscUpdateSubscription(STscObj* pObj, SSub* pSub) {
+  int code = (uint8_t)tsParseSql(pSub->pSql, pObj->acctId, pObj->db, false);
+  if (code != TSDB_CODE_SUCCESS) {
+    taos_unsubscribe(pSub);
+    return false;
+  }
+
+  int numOfMeters = 0;
+  SSubscriptionProgress* progress = NULL;
+
+// ??? if there's more than one vnode
+  SSqlCmd* pCmd = &pSub->pSql->cmd;
+
+  SMeterMetaInfo *pMeterMetaInfo = tscGetMeterMetaInfo(pCmd, 0);
+  if (UTIL_METER_IS_NOMRAL_METER(pMeterMetaInfo)) {
+    numOfMeters = 1;
+    progress = calloc(1, sizeof(SSubscriptionProgress));
+    int64_t uid = pMeterMetaInfo->pMeterMeta->uid;
+    progress[0].uid = uid;
+    progress[0].key = tscGetSubscriptionProgress(pSub->pSql, uid);
+  } else {
+    SMetricMeta* pMetricMeta = pMeterMetaInfo->pMetricMeta;
+    SVnodeSidList *pVnodeSidList = tscGetVnodeSidList(pMetricMeta, pMeterMetaInfo->vnodeIndex);
+    numOfMeters = pVnodeSidList->numOfSids;
+    progress = calloc(numOfMeters, sizeof(SSubscriptionProgress));
+    for (int32_t i = 0; i < numOfMeters; ++i) {
+      SMeterSidExtInfo *pMeterInfo = tscGetMeterSidInfo(pVnodeSidList, i);
+      int64_t uid = pMeterInfo->uid;
+      progress[i].uid = uid;
+      progress[i].key = tscGetSubscriptionProgress(pSub->pSql, uid);
+    }
+    qsort(progress, numOfMeters, sizeof(SSubscriptionProgress), tscCompareSubscriptionProgress);
+  }
+
+  free(pSub->progress);
+  pSub->numOfMeters = numOfMeters;
+  pSub->progress = progress;
+
+  // timestamp must in the output column
+  SFieldInfo* pFieldInfo = &pCmd->fieldsInfo;
+  tscFieldInfoSetValue(pFieldInfo, pFieldInfo->numOfOutputCols, TSDB_DATA_TYPE_TIMESTAMP, "_c0", TSDB_KEYSIZE);
+  tscSqlExprInsertEmpty(pCmd, pFieldInfo->numOfOutputCols - 1, TSDB_FUNC_PRJ);
+  tscFieldInfoUpdateVisible(pFieldInfo, pFieldInfo->numOfOutputCols - 1, false);
+  tscFieldInfoCalOffset(pCmd);
+
+  pSub->lastSyncTime = taosGetTimestampMs();
+
+  return true;
+}
+
+
 TAOS_SUB *taos_subscribe(TAOS *taos, const char *sql, TAOS_SUBSCRIBE_CALLBACK fp, void *param, int interval) {
   STscObj* pObj = (STscObj*)taos;
   if (pObj == NULL || pObj->signature != pObj) {
@@ -164,40 +216,12 @@ TAOS_SUB *taos_subscribe(TAOS *taos, const char *sql, TAOS_SUBSCRIBE_CALLBACK fp
   if (pSub == NULL) {
     return NULL;
   }
+  pSub->taos = taos;
 
-  int code = (uint8_t)tsParseSql(pSub->pSql, pObj->acctId, pObj->db, false);
-  if (code != TSDB_CODE_SUCCESS) {
-    taos_unsubscribe(pSub);
+  if (!tscUpdateSubscription(pObj, pSub)) {
     return NULL;
   }
 
-// ??? if there's more than one vnode
-  SSqlCmd* pCmd = &pSub->pSql->cmd;
-
-  SMeterMetaInfo *pMeterMetaInfo = tscGetMeterMetaInfo(pCmd, 0);
-  if (UTIL_METER_IS_NOMRAL_METER(pMeterMetaInfo)) {
-    pSub->numOfMeters = 1;
-    pSub->progress = calloc(1, sizeof(SSubscriptionProgress));
-    pSub->progress[0].uid = pMeterMetaInfo->pMeterMeta->uid;
-  } else {
-    SMetricMeta* pMetricMeta = pMeterMetaInfo->pMetricMeta;
-    SVnodeSidList *pVnodeSidList = tscGetVnodeSidList(pMetricMeta, pMeterMetaInfo->vnodeIndex);
-    pSub->numOfMeters = pVnodeSidList->numOfSids;
-    pSub->progress = calloc(pSub->numOfMeters, sizeof(SSubscriptionProgress));
-    for (int32_t i = 0; i < pSub->numOfMeters; ++i) {
-      SMeterSidExtInfo *pMeterInfo = tscGetMeterSidInfo(pVnodeSidList, i);
-      pSub->progress[i].uid = pMeterInfo->uid;
-    }
-    qsort(pSub->progress, pSub->numOfMeters, sizeof(SSubscriptionProgress), tscCompareSubscriptionProgress);
-  }
-
-  // timestamp must in the output column
-  SFieldInfo* pFieldInfo = &pCmd->fieldsInfo;
-  tscFieldInfoSetValue(pFieldInfo, pFieldInfo->numOfOutputCols, TSDB_DATA_TYPE_TIMESTAMP, "_c0", TSDB_KEYSIZE);
-  tscSqlExprInsertEmpty(pCmd, pFieldInfo->numOfOutputCols - 1, TSDB_FUNC_PRJ);
-  tscFieldInfoUpdateVisible(pFieldInfo, pFieldInfo->numOfOutputCols - 1, false);
-  tscFieldInfoCalOffset(pCmd);
-
   if (fp != NULL) {
     pSub->fp = fp;
     pSub->interval = interval;
@@ -212,6 +236,12 @@ TAOS_RES *taos_consume(TAOS_SUB *tsub) {
   SSub *pSub = (SSub *)tsub;
   if (pSub == NULL) return NULL;
 
+  if (taosGetTimestampMs() - pSub->lastSyncTime > 30 * 10 * 1000) {
+    taos_query(pSub->taos, "reset query cache;");
+    // TODO: clear memory
+    if (!tscUpdateSubscription(pSub->taos, pSub)) return NULL;
+  }
+
   SSqlObj* pSql = pSub->pSql;
   SSqlRes *pRes = &pSql->res;
 
diff --git a/src/system/detail/src/vnodeRead.c b/src/system/detail/src/vnodeRead.c
index 2a913665cd..9612cc6eb6 100644
--- a/src/system/detail/src/vnodeRead.c
+++ b/src/system/detail/src/vnodeRead.c
@@ -1105,6 +1105,7 @@ int32_t vnodeConvertQueryMeterMsg(SQueryMeterMsg *pQueryMsg) {
   pSids[0] = (SMeterSidExtInfo *)pMsg;
   pSids[0]->sid = htonl(pSids[0]->sid);
   pSids[0]->uid = htobe64(pSids[0]->uid);
+  pSids[0]->key = htobe64(pSids[0]->key);
   
   for (int32_t j = 1; j < pQueryMsg->numOfSids; ++j) {
     pSids[j] = (SMeterSidExtInfo *)((char *)pSids[j - 1] + sizeof(SMeterSidExtInfo) + pQueryMsg->tagLength);
diff --git a/src/system/detail/src/vnodeShell.c b/src/system/detail/src/vnodeShell.c
index 2c8fe35cca..e527164df1 100644
--- a/src/system/detail/src/vnodeShell.c
+++ b/src/system/detail/src/vnodeShell.c
@@ -441,7 +441,9 @@ void vnodeExecuteRetrieveReq(SSchedMsg *pSched) {
 
   // buffer size for progress information, including meter count,
   // and for each meter, including 'uid' and 'TSKEY'.
-  int progressSize = pQInfo->pMeterQuerySupporter->numOfMeters * (sizeof(int64_t) + sizeof(TSKEY)) + sizeof(int32_t);
+  int progressSize = 0;
+  if (pQInfo->pMeterQuerySupporter != NULL)
+    progressSize = pQInfo->pMeterQuerySupporter->numOfMeters * (sizeof(int64_t) + sizeof(TSKEY)) + sizeof(int32_t);
 
   pStart = taosBuildRspMsgWithSize(pObj->thandle, TSDB_MSG_TYPE_RETRIEVE_RSP, progressSize + size + 100);
   if (pStart == NULL) {
@@ -476,13 +478,15 @@ void vnodeExecuteRetrieveReq(SSchedMsg *pSched) {
 
   // write the progress information of each meter to response
   // this is required by subscriptions
-  *((int32_t*)pMsg) = htonl(pQInfo->pMeterQuerySupporter->numOfMeters);
-  pMsg += sizeof(int32_t);
-  for (int32_t i = 0; i < pQInfo->pMeterQuerySupporter->numOfMeters; i++) {
-    *((int64_t*)pMsg) = htobe64(pQInfo->pMeterQuerySupporter->pMeterSidExtInfo[i]->uid);
-    pMsg += sizeof(int64_t);
-    *((TSKEY*)pMsg) = htobe64(pQInfo->pMeterQuerySupporter->pMeterSidExtInfo[i]->key);
-    pMsg += sizeof(TSKEY);
+  if (progressSize > 0) {
+    *((int32_t*)pMsg) = htonl(pQInfo->pMeterQuerySupporter->numOfMeters);
+    pMsg += sizeof(int32_t);
+    for (int32_t i = 0; i < pQInfo->pMeterQuerySupporter->numOfMeters; i++) {
+      *((int64_t*)pMsg) = htobe64(pQInfo->pMeterQuerySupporter->pMeterSidExtInfo[i]->uid);
+      pMsg += sizeof(int64_t);
+      *((TSKEY*)pMsg) = htobe64(pQInfo->pMeterQuerySupporter->pMeterSidExtInfo[i]->key);
+      pMsg += sizeof(TSKEY);
+    }
   }
 
   msgLen = pMsg - pStart;

From 4ba0819f58220ae4a96c26b81a4eefb57a4246d9 Mon Sep 17 00:00:00 2001
From: localvar <localvar@hotmail.com>
Date: Thu, 2 Jan 2020 16:50:33 +0800
Subject: [PATCH 06/35] TBASE-1424, TBASE-1425: save & load subscription
 progress.

---
 src/client/src/tscServer.c                |  12 ++-
 src/client/src/tscSub.c                   | 124 +++++++++++++++++++---
 src/inc/taos.h                            |   2 +-
 src/system/detail/src/vnodeQueryProcess.c |   4 -
 tests/examples/c/subscribe.c              |  14 ++-
 5 files changed, 126 insertions(+), 30 deletions(-)

diff --git a/src/client/src/tscServer.c b/src/client/src/tscServer.c
index 03b66a1996..0972e5fe2d 100644
--- a/src/client/src/tscServer.c
+++ b/src/client/src/tscServer.c
@@ -46,8 +46,9 @@ int (*tscProcessMsgRsp[TSDB_SQL_MAX])(SSqlObj *pSql);
 void (*tscUpdateVnodeMsg[TSDB_SQL_MAX])(SSqlObj *pSql, char *buf);
 void tscProcessActivityTimer(void *handle, void *tmrId);
 int tscKeepConn[TSDB_SQL_MAX] = {0};
-TSKEY tscGetSubscriptionProgress(SSqlObj* pSql, int64_t uid);
-void tscUpdateSubscriptionProgress(SSqlObj* pSql, int64_t uid, TSKEY ts);
+TSKEY tscGetSubscriptionProgress(void* sub, int64_t uid);
+void tscUpdateSubscriptionProgress(void* sub, int64_t uid, TSKEY ts);
+void tscSaveSubscriptionProgress(void* sub);
 
 static int32_t minMsgSize() { return tsRpcHeadSize + sizeof(STaosDigest); }
 
@@ -1533,7 +1534,7 @@ static char* doSerializeTableInfo(SSqlObj* pSql, int32_t numOfMeters, int32_t vn
     SMeterSidExtInfo *pMeterInfo = (SMeterSidExtInfo *)pMsg;
     pMeterInfo->sid = htonl(pMeterMeta->sid);
     pMeterInfo->uid = htobe64(pMeterMeta->uid);
-    pMeterInfo->key = htobe64(tscGetSubscriptionProgress(pSql, pMeterMeta->uid));
+    pMeterInfo->key = htobe64(tscGetSubscriptionProgress(pSql->pSubscription, pMeterMeta->uid));
     pMsg += sizeof(SMeterSidExtInfo);
   } else {
     SVnodeSidList *pVnodeSidList = tscGetVnodeSidList(pMetricMeta, pMeterMetaInfo->vnodeIndex);
@@ -1544,7 +1545,7 @@ static char* doSerializeTableInfo(SSqlObj* pSql, int32_t numOfMeters, int32_t vn
       
       pMeterInfo->sid = htonl(pQueryMeterInfo->sid);
       pMeterInfo->uid = htobe64(pQueryMeterInfo->uid);
-      pMeterInfo->key = htobe64(tscGetSubscriptionProgress(pSql, pQueryMeterInfo->uid));
+      pMeterInfo->key = htobe64(tscGetSubscriptionProgress(pSql->pSubscription, pQueryMeterInfo->uid));
       
       pMsg += sizeof(SMeterSidExtInfo);
       
@@ -3555,8 +3556,9 @@ int tscProcessRetrieveRspFromVnode(SSqlObj *pSql) {
       p += sizeof(int64_t);
       TSKEY key = htobe64(*(TSKEY*)p);
       p += sizeof(TSKEY);
-      tscUpdateSubscriptionProgress(pSql, uid, key);
+      tscUpdateSubscriptionProgress(pSql->pSubscription, uid, key);
     }
+    tscSaveSubscriptionProgress(pSql->pSubscription);
   }
 
   pRes->row = 0;
diff --git a/src/client/src/tscSub.c b/src/client/src/tscSub.c
index 079c7441ce..910f9412f2 100644
--- a/src/client/src/tscSub.c
+++ b/src/client/src/tscSub.c
@@ -32,6 +32,7 @@ typedef struct SSubscriptionProgress {
 } SSubscriptionProgress;
 
 typedef struct SSub {
+  char                    topic[32];
   int64_t                 lastSyncTime;
   void *                  signature;
   TAOS *                  taos;
@@ -49,11 +50,11 @@ static int tscCompareSubscriptionProgress(const void* a, const void* b) {
   return ((const SSubscriptionProgress*)a)->uid - ((const SSubscriptionProgress*)b)->uid;
 }
 
-TSKEY tscGetSubscriptionProgress(SSqlObj* pSql, int64_t uid) {
-  if( pSql == NULL || pSql->pSubscription == NULL)
+TSKEY tscGetSubscriptionProgress(void* sub, int64_t uid) {
+  if (sub == NULL)
     return 0;
 
-  SSub* pSub = (SSub*)pSql->pSubscription;
+  SSub* pSub = (SSub*)sub;
   for (int s = 0, e = pSub->numOfMeters; s < e;) {
     int m = (s + e) / 2;
     SSubscriptionProgress* p = pSub->progress + m;
@@ -68,11 +69,11 @@ TSKEY tscGetSubscriptionProgress(SSqlObj* pSql, int64_t uid) {
   return 0;
 }
 
-void tscUpdateSubscriptionProgress(SSqlObj* pSql, int64_t uid, TSKEY ts) {
-  if( pSql == NULL || pSql->pSubscription == NULL)
+void tscUpdateSubscriptionProgress(void* sub, int64_t uid, TSKEY ts) {
+  if( sub == NULL)
     return;
 
-  SSub* pSub = (SSub*)pSql->pSubscription;
+  SSub* pSub = (SSub*)sub;
   for (int s = 0, e = pSub->numOfMeters; s < e;) {
     int m = (s + e) / 2;
     SSubscriptionProgress* p = pSub->progress + m;
@@ -88,7 +89,7 @@ void tscUpdateSubscriptionProgress(SSqlObj* pSql, int64_t uid, TSKEY ts) {
 }
 
 
-static SSub* tscCreateSubscription(STscObj* pObj, const char* sql) {
+static SSub* tscCreateSubscription(STscObj* pObj, const char* topic, const char* sql) {
   SSub* pSub = calloc(1, sizeof(SSub));
   if (pSub == NULL) {
     globalCode = TSDB_CODE_CLI_OUT_OF_MEMORY;
@@ -125,6 +126,7 @@ static SSub* tscCreateSubscription(STscObj* pObj, const char* sql) {
   pSql->pSubscription = pSub;
   pSub->pSql = pSql;
   pSub->signature = pSub;
+  strncpy(pSub->topic, topic, sizeof(pSub->topic));
   return pSub;
 
 failed:
@@ -139,7 +141,7 @@ failed:
 }
 
 
-static void tscProcessSubscribeTimer(void *handle, void *tmrId) {
+static void tscProcessSubscriptionTimer(void *handle, void *tmrId) {
   SSub *pSub = (SSub *)handle;
   if (pSub == NULL || pSub->pTimer != tmrId) return;
 
@@ -149,7 +151,7 @@ static void tscProcessSubscribeTimer(void *handle, void *tmrId) {
     // TODO: memory leak
   }
 
-  taosTmrReset(tscProcessSubscribeTimer, pSub->interval, pSub, tscTmr, &pSub->pTimer);
+  taosTmrReset(tscProcessSubscriptionTimer, pSub->interval, pSub, tscTmr, &pSub->pTimer);
 }
 
 
@@ -172,7 +174,7 @@ bool tscUpdateSubscription(STscObj* pObj, SSub* pSub) {
     progress = calloc(1, sizeof(SSubscriptionProgress));
     int64_t uid = pMeterMetaInfo->pMeterMeta->uid;
     progress[0].uid = uid;
-    progress[0].key = tscGetSubscriptionProgress(pSub->pSql, uid);
+    progress[0].key = tscGetSubscriptionProgress(pSub, uid);
   } else {
     SMetricMeta* pMetricMeta = pMeterMetaInfo->pMetricMeta;
     SVnodeSidList *pVnodeSidList = tscGetVnodeSidList(pMetricMeta, pMeterMetaInfo->vnodeIndex);
@@ -182,7 +184,7 @@ bool tscUpdateSubscription(STscObj* pObj, SSub* pSub) {
       SMeterSidExtInfo *pMeterInfo = tscGetMeterSidInfo(pVnodeSidList, i);
       int64_t uid = pMeterInfo->uid;
       progress[i].uid = uid;
-      progress[i].key = tscGetSubscriptionProgress(pSub->pSql, uid);
+      progress[i].key = tscGetSubscriptionProgress(pSub, uid);
     }
     qsort(progress, numOfMeters, sizeof(SSubscriptionProgress), tscCompareSubscriptionProgress);
   }
@@ -204,7 +206,93 @@ bool tscUpdateSubscription(STscObj* pObj, SSub* pSub) {
 }
 
 
-TAOS_SUB *taos_subscribe(TAOS *taos, const char *sql, TAOS_SUBSCRIBE_CALLBACK fp, void *param, int interval) {
+static void tscLoadSubscriptionProgress(SSub* pSub) {
+  char buf[TSDB_MAX_SQL_LEN];
+  sprintf(buf, "%s/subscribe/%s", dataDir, pSub->topic);
+
+  FILE* fp = fopen(buf, "r");
+  if (fp == NULL) {
+    tscTrace("subscription progress file does not exist: %s", pSub->topic);
+    return true;
+  }
+
+  if (fgets(buf, sizeof(buf), fp) == NULL) {
+    tscTrace("invalid subscription progress file: %s", pSub->topic);
+    fclose(fp);
+    return false;
+  }
+
+  for (int i = 0; i < sizeof(buf); i++) {
+    if (buf[i] == 0)
+      break;
+    if (buf[i] == '\r' || buf[i] == '\n') {
+      buf[i] = 0;
+      break;
+    }
+  }
+  if (strcmp(buf, pSub->pSql->sqlstr) != 0) {
+    tscTrace("subscription sql statement mismatch: %s", pSub->topic);
+    fclose(fp);
+    return false;
+  }
+
+  if (fgets(buf, sizeof(buf), fp) == NULL || atoi(buf) < 0) {
+    tscTrace("invalid subscription progress file: %s", pSub->topic);
+    fclose(fp);
+    return false;
+  }
+
+  int numOfMeters = atoi(buf);
+  SSubscriptionProgress* progress = calloc(numOfMeters, sizeof(SSubscriptionProgress));
+  for (int i = 0; i < numOfMeters; i++) {
+    if (fgets(buf, sizeof(buf), fp) == NULL) {
+      fclose(fp);
+      free(progress);
+      return false;
+    }
+    int64_t uid, key;
+    sscanf(buf, "uid=%" SCNd64 ",progress=%" SCNd64, &uid, &key);
+    progress[i].uid = uid;
+    progress[i].key = key;
+  }
+
+  fclose(fp);
+
+  qsort(progress, numOfMeters, sizeof(SSubscriptionProgress), tscCompareSubscriptionProgress);
+  pSub->numOfMeters = numOfMeters;
+  pSub->progress = progress;
+  return true;
+}
+
+void tscSaveSubscriptionProgress(void* sub) {
+  SSub* pSub = (SSub*)sub;
+
+  char path[256];
+  sprintf(path, "%s/subscribe", dataDir);
+  if (access(path, 0) != 0) {
+    mkdir(path, 0777);
+  }
+
+  sprintf(path, "%s/subscribe/%s", dataDir, pSub->topic);
+  FILE* fp = fopen(path, "w+");
+  if (fp == NULL) {
+    tscError("failed to create progress file for subscription: %s", pSub->topic);
+    return;
+  }
+
+  fputs(pSub->pSql->sqlstr, fp);
+  fprintf(fp, "\n%d\n", pSub->numOfMeters);
+  for (int i = 0; i < pSub->numOfMeters; i++) {
+    int64_t uid = pSub->progress[i].uid;
+    TSKEY key = pSub->progress[i].key;
+    fprintf(fp, "uid=%" PRId64 ",progress=%" PRId64 "\n", uid, key);
+  }
+
+  fclose(fp);
+}
+
+
+TAOS_SUB *taos_subscribe(const char* topic, int restart, TAOS *taos, const char *sql, TAOS_SUBSCRIBE_CALLBACK fp, void *param, int interval) {
   STscObj* pObj = (STscObj*)taos;
   if (pObj == NULL || pObj->signature != pObj) {
     globalCode = TSDB_CODE_DISCONNECTED;
@@ -212,12 +300,18 @@ TAOS_SUB *taos_subscribe(TAOS *taos, const char *sql, TAOS_SUBSCRIBE_CALLBACK fp
     return NULL;
   }
 
-  SSub* pSub = tscCreateSubscription(pObj, sql);
+  SSub* pSub = tscCreateSubscription(pObj, topic, sql);
   if (pSub == NULL) {
     return NULL;
   }
   pSub->taos = taos;
 
+  if (restart) {
+    tscTrace("restart subscription: %s", topic);
+  } else {
+    tscLoadSubscriptionProgress(pSub);
+  }
+
   if (!tscUpdateSubscription(pObj, pSub)) {
     return NULL;
   }
@@ -226,7 +320,7 @@ TAOS_SUB *taos_subscribe(TAOS *taos, const char *sql, TAOS_SUBSCRIBE_CALLBACK fp
     pSub->fp = fp;
     pSub->interval = interval;
     pSub->param = param;
-    taosTmrReset(tscProcessSubscribeTimer, 0, pSub, tscTmr, &pSub->pTimer);
+    taosTmrReset(tscProcessSubscriptionTimer, 0, pSub, tscTmr, &pSub->pTimer);
   }
 
   return pSub;
@@ -236,7 +330,7 @@ TAOS_RES *taos_consume(TAOS_SUB *tsub) {
   SSub *pSub = (SSub *)tsub;
   if (pSub == NULL) return NULL;
 
-  if (taosGetTimestampMs() - pSub->lastSyncTime > 30 * 10 * 1000) {
+  if (taosGetTimestampMs() - pSub->lastSyncTime > 30 * 60 * 1000) {
     taos_query(pSub->taos, "reset query cache;");
     // TODO: clear memory
     if (!tscUpdateSubscription(pSub->taos, pSub)) return NULL;
diff --git a/src/inc/taos.h b/src/inc/taos.h
index aa2ed02f9b..bdba644bb6 100644
--- a/src/inc/taos.h
+++ b/src/inc/taos.h
@@ -117,7 +117,7 @@ DLL_EXPORT void taos_fetch_rows_a(TAOS_RES *res, void (*fp)(void *param, TAOS_RE
 DLL_EXPORT void taos_fetch_row_a(TAOS_RES *res, void (*fp)(void *param, TAOS_RES *, TAOS_ROW row), void *param);
 
 typedef void (*TAOS_SUBSCRIBE_CALLBACK)(TAOS_SUB* tsub, TAOS_RES *res, void* param, int code);
-DLL_EXPORT TAOS_SUB *taos_subscribe(TAOS *taos, const char *sql, TAOS_SUBSCRIBE_CALLBACK fp, void *param, int interval);
+DLL_EXPORT TAOS_SUB *taos_subscribe(const char* topic, int restart, TAOS *taos, const char *sql, TAOS_SUBSCRIBE_CALLBACK fp, void *param, int interval);
 DLL_EXPORT TAOS_RES *taos_consume(TAOS_SUB *tsub);
 DLL_EXPORT void      taos_unsubscribe(TAOS_SUB *tsub);
 
diff --git a/src/system/detail/src/vnodeQueryProcess.c b/src/system/detail/src/vnodeQueryProcess.c
index ae73ba5249..cc1733a747 100644
--- a/src/system/detail/src/vnodeQueryProcess.c
+++ b/src/system/detail/src/vnodeQueryProcess.c
@@ -682,18 +682,14 @@ static void vnodeMultiMeterMultiOutputProcessor(SQInfo *pQInfo) {
     while (pSupporter->meterIdx < pSupporter->numOfMeters) {
       int32_t k = pSupporter->meterIdx;
 
-pQInfo->killed = 0;
-/*
       if (isQueryKilled(pQuery)) {
         setQueryStatus(pQuery, QUERY_NO_DATA_TO_CHECK);
         return;
       }
-*/
 
       TSKEY skey = pQInfo->pMeterQuerySupporter->pMeterSidExtInfo[k]->key;
       if (skey > 0) {
         pQuery->skey = skey;
-        // pQuery->lastKey = ???;
       }
 
       bool dataInDisk = true;
diff --git a/tests/examples/c/subscribe.c b/tests/examples/c/subscribe.c
index b35dca772f..7c76e1088c 100644
--- a/tests/examples/c/subscribe.c
+++ b/tests/examples/c/subscribe.c
@@ -28,7 +28,7 @@ int main(int argc, char *argv[]) {
   const char* host = "127.0.0.1";
   const char* user = "root";
   const char* passwd = "taosdata";
-  int async = 1;
+  int async = 1, restart = 0;
   TAOS_SUB* tsub = NULL;
 
   for (int i = 1; i < argc; i++) {
@@ -44,8 +44,12 @@ int main(int argc, char *argv[]) {
       passwd = argv[i] + 3;
       continue;
     }
-    if (strncmp(argv[i], "-m=", 3) == 0) {
-      async = strcmp(argv[i] + 3, "sync");
+    if (strcmp(argv[i], "-sync") == 0) {
+      async = 0;
+      continue;
+    }
+    if (strcmp(argv[i], "-restart") == 0) {
+      restart = 1;
       continue;
     }
   }
@@ -60,9 +64,9 @@ int main(int argc, char *argv[]) {
   }
 
   if (async) {
-    tsub = taos_subscribe(taos, "select * from meters;", subscribe_callback, NULL, 1000);
+    tsub = taos_subscribe("test", restart, taos, "select * from meters;", subscribe_callback, NULL, 1000);
   } else {
-    tsub = taos_subscribe(taos, "select * from meters;", NULL, NULL, 0);
+    tsub = taos_subscribe("test", restart, taos, "select * from meters;", NULL, NULL, 0);
   }
 
   if (tsub == NULL) {

From f2eac06a3389f1afcee9a5b0b49ca1954c936d8e Mon Sep 17 00:00:00 2001
From: localvar <localvar@hotmail.com>
Date: Thu, 2 Jan 2020 17:52:45 +0800
Subject: [PATCH 07/35] TBASE-1423: single meter subscription

---
 src/system/detail/src/vnodeRead.c  |  8 +++++++-
 src/system/detail/src/vnodeShell.c | 11 ++++++++++-
 tests/examples/c/makefile          |  9 +++++----
 tests/examples/c/subscribe.c       |  9 +++++++--
 4 files changed, 29 insertions(+), 8 deletions(-)

diff --git a/src/system/detail/src/vnodeRead.c b/src/system/detail/src/vnodeRead.c
index 9612cc6eb6..be5cf5e6f6 100644
--- a/src/system/detail/src/vnodeRead.c
+++ b/src/system/detail/src/vnodeRead.c
@@ -630,7 +630,13 @@ void *vnodeQueryOnSingleTable(SMeterObj **pMetersObj, SSqlGroupbyExpr *pGroupbyE
   pQuery = &(pQInfo->query);
   dTrace("qmsg:%p create QInfo:%p, QInfo created", pQueryMsg, pQInfo);
 
-  pQuery->skey = pQueryMsg->skey;
+  SMeterSidExtInfo** pSids = (SMeterSidExtInfo**)pQueryMsg->pSidExtInfo;
+  if (pSids != NULL && pSids[0]->key > 0) {
+    pQuery->skey = pSids[0]->key;
+  } else {
+    pQuery->skey = pQueryMsg->skey;
+  }
+
   pQuery->ekey = pQueryMsg->ekey;
   pQuery->lastKey = pQuery->skey;
 
diff --git a/src/system/detail/src/vnodeShell.c b/src/system/detail/src/vnodeShell.c
index e527164df1..66cc16d9df 100644
--- a/src/system/detail/src/vnodeShell.c
+++ b/src/system/detail/src/vnodeShell.c
@@ -444,6 +444,8 @@ void vnodeExecuteRetrieveReq(SSchedMsg *pSched) {
   int progressSize = 0;
   if (pQInfo->pMeterQuerySupporter != NULL)
     progressSize = pQInfo->pMeterQuerySupporter->numOfMeters * (sizeof(int64_t) + sizeof(TSKEY)) + sizeof(int32_t);
+  else if (pQInfo->pObj != NULL)
+    progressSize = sizeof(int64_t) + sizeof(TSKEY) + sizeof(int32_t);
 
   pStart = taosBuildRspMsgWithSize(pObj->thandle, TSDB_MSG_TYPE_RETRIEVE_RSP, progressSize + size + 100);
   if (pStart == NULL) {
@@ -478,7 +480,7 @@ void vnodeExecuteRetrieveReq(SSchedMsg *pSched) {
 
   // write the progress information of each meter to response
   // this is required by subscriptions
-  if (progressSize > 0) {
+  if (pQInfo->pMeterQuerySupporter != NULL) {
     *((int32_t*)pMsg) = htonl(pQInfo->pMeterQuerySupporter->numOfMeters);
     pMsg += sizeof(int32_t);
     for (int32_t i = 0; i < pQInfo->pMeterQuerySupporter->numOfMeters; i++) {
@@ -487,6 +489,13 @@ void vnodeExecuteRetrieveReq(SSchedMsg *pSched) {
       *((TSKEY*)pMsg) = htobe64(pQInfo->pMeterQuerySupporter->pMeterSidExtInfo[i]->key);
       pMsg += sizeof(TSKEY);
     }
+  } else if (pQInfo->pObj != NULL) {
+    *((int32_t*)pMsg) = htonl(1);
+    pMsg += sizeof(int32_t);
+    *((int64_t*)pMsg) = htobe64(pQInfo->pObj->uid);
+    pMsg += sizeof(int64_t);
+    *((TSKEY*)pMsg) = htobe64(pQInfo->query.lastKey);
+    pMsg += sizeof(TSKEY);
   }
 
   msgLen = pMsg - pStart;
diff --git a/tests/examples/c/makefile b/tests/examples/c/makefile
index d68a734e95..0a4b8ee9d2 100644
--- a/tests/examples/c/makefile
+++ b/tests/examples/c/makefile
@@ -4,16 +4,17 @@
 ROOT=./
 TARGET=exe
 LFLAGS = '-Wl,-rpath,/usr/local/taos/driver/' -ltaos -lpthread -lm -lrt
+#LFLAGS = '-Wl,-rpath,/home/zbm/project/td/debug/build/lib/' -L/home/zbm/project/td/debug/build/lib -ltaos -lpthread -lm -lrt
 CFLAGS = -O3 -g -Wall -Wno-deprecated -fPIC -Wno-unused-result -Wconversion -Wno-char-subscripts -D_REENTRANT -Wno-format -D_REENTRANT -DLINUX -msse4.2 -Wno-unused-function -D_M_X64 \
 	-I/usr/local/taos/include -std=gnu99
 
 all: $(TARGET)
 
 exe:
-gcc $(CFLAGS) ./asyncdemo.c -o $(ROOT)/asyncdemo $(LFLAGS)
-gcc $(CFLAGS) ./demo.c -o $(ROOT)/demo $(LFLAGS)
-gcc $(CFLAGS) ./prepare.c -o $(ROOT)/prepare $(LFLAGS)
-gcc $(CFLAGS) ./stream.c -o $(ROOT)/stream $(LFLAGS)
+	gcc $(CFLAGS) ./asyncdemo.c -o $(ROOT)/asyncdemo $(LFLAGS)
+	gcc $(CFLAGS) ./demo.c -o $(ROOT)/demo $(LFLAGS)
+	gcc $(CFLAGS) ./prepare.c -o $(ROOT)/prepare $(LFLAGS)
+	gcc $(CFLAGS) ./stream.c -o $(ROOT)/stream $(LFLAGS)
 	gcc $(CFLAGS) ./subscribe.c -o $(ROOT)subscribe $(LFLAGS)
 
 clean:
diff --git a/tests/examples/c/subscribe.c b/tests/examples/c/subscribe.c
index 7c76e1088c..c81246bac6 100644
--- a/tests/examples/c/subscribe.c
+++ b/tests/examples/c/subscribe.c
@@ -28,6 +28,7 @@ int main(int argc, char *argv[]) {
   const char* host = "127.0.0.1";
   const char* user = "root";
   const char* passwd = "taosdata";
+  const char* sql = "select * from meters;";
   int async = 1, restart = 0;
   TAOS_SUB* tsub = NULL;
 
@@ -52,6 +53,10 @@ int main(int argc, char *argv[]) {
       restart = 1;
       continue;
     }
+    if (strcmp(argv[i], "-single") == 0) {
+      sql = "select * from t0;";
+      continue;
+    }
   }
 
   // init TAOS
@@ -64,9 +69,9 @@ int main(int argc, char *argv[]) {
   }
 
   if (async) {
-    tsub = taos_subscribe("test", restart, taos, "select * from meters;", subscribe_callback, NULL, 1000);
+    tsub = taos_subscribe("test", restart, taos, sql, subscribe_callback, NULL, 1000);
   } else {
-    tsub = taos_subscribe("test", restart, taos, "select * from meters;", NULL, NULL, 0);
+    tsub = taos_subscribe("test", restart, taos, sql, NULL, NULL, 0);
   }
 
   if (tsub == NULL) {

From 051af216a5137dd7172034965a94d2987256cd4c Mon Sep 17 00:00:00 2001
From: localvar <localvar@hotmail.com>
Date: Sat, 4 Jan 2020 13:39:26 +0800
Subject: [PATCH 08/35] tbase-1422: free resource

---
 src/client/inc/tsclient.h    |   6 +++
 src/client/src/tscSql.c      |  20 +++++--
 src/client/src/tscSub.c      | 101 +++++++++++++++++++++--------------
 src/client/src/tscUtil.c     |  28 +++++-----
 src/inc/taos.h               |   2 +-
 tests/examples/c/subscribe.c |  14 +++--
 6 files changed, 110 insertions(+), 61 deletions(-)

diff --git a/src/client/inc/tsclient.h b/src/client/inc/tsclient.h
index e91b05d104..da91dc5649 100644
--- a/src/client/inc/tsclient.h
+++ b/src/client/inc/tsclient.h
@@ -465,6 +465,12 @@ void    tscDestroyResPointerInfo(SSqlRes *pRes);
 
 void tscFreeSqlCmdData(SSqlCmd *pCmd);
 
+/**
+ * free query result of the sql object
+ * @param pObj
+ */
+void tscFreeSqlResult(SSqlObj* pSql);
+
 /**
  * only free part of resources allocated during query.
  * Note: this function is multi-thread safe.
diff --git a/src/client/src/tscSql.c b/src/client/src/tscSql.c
index 9c812d4187..ad4a29f20e 100644
--- a/src/client/src/tscSql.c
+++ b/src/client/src/tscSql.c
@@ -694,7 +694,7 @@ int taos_select_db(TAOS *taos, const char *db) {
   return taos_query(taos, sql);
 }
 
-void taos_free_result(TAOS_RES *res) {
+void taos_free_result_imp(TAOS_RES* res, int keepCmd) {
   if (res == NULL) return;
 
   SSqlObj *pSql = (SSqlObj *)res;
@@ -712,6 +712,8 @@ void taos_free_result(TAOS_RES *res) {
       pSql->thandle = NULL;
       tscFreeSqlObj(pSql);
       tscTrace("%p Async SqlObj is freed by app", pSql);
+    } else if (keepCmd) {
+      tscFreeSqlResult(pSql);
     } else {
       tscFreeSqlObjPartial(pSql);
     }
@@ -761,8 +763,13 @@ void taos_free_result(TAOS_RES *res) {
        * Then this object will be reused and no free operation is required.
        */
       pSql->thandle = NULL;
-      tscFreeSqlObjPartial(pSql);
-      tscTrace("%p sql result is freed by app", pSql);
+      if (keepCmd) {
+        tscFreeSqlResult(pSql);
+        tscTrace("%p sql result is freed by app while sql command is kept", pSql);
+      } else {
+        tscFreeSqlObjPartial(pSql);
+        tscTrace("%p sql result is freed by app", pSql);
+      }
     }
   } else {
     // if no free resource msg is sent to vnode, we free this object immediately.
@@ -772,6 +779,9 @@ void taos_free_result(TAOS_RES *res) {
       assert(pRes->numOfRows == 0 || (pCmd->command > TSDB_SQL_LOCAL));
       tscFreeSqlObj(pSql);
       tscTrace("%p Async sql result is freed by app", pSql);
+    } else if (keepCmd) {
+      tscFreeSqlResult(pSql);
+      tscTrace("%p sql result is freed while sql command is kept", pSql);
     } else {
       tscFreeSqlObjPartial(pSql);
       tscTrace("%p sql result is freed", pSql);
@@ -779,6 +789,10 @@ void taos_free_result(TAOS_RES *res) {
   }
 }
 
+void taos_free_result(TAOS_RES *res) {
+  taos_free_result_imp(res, 0);
+}
+
 int taos_errno(TAOS *taos) {
   STscObj *pObj = (STscObj *)taos;
   int      code;
diff --git a/src/client/src/tscSub.c b/src/client/src/tscSub.c
index 910f9412f2..b2c332deff 100644
--- a/src/client/src/tscSub.c
+++ b/src/client/src/tscSub.c
@@ -25,6 +25,7 @@
 #include "ttimer.h"
 #include "tutil.h"
 #include "tscUtil.h"
+#include "tcache.h"
 
 typedef struct SSubscriptionProgress {
   int64_t uid;
@@ -82,7 +83,7 @@ void tscUpdateSubscriptionProgress(void* sub, int64_t uid, TSKEY ts) {
     else if (p->uid < uid)
       s = m + 1;
     else {
-      if (ts >= p->key) p->key = ts + 1;
+      if (ts >= p->key) p->key = ts;
       break;
     }
   }
@@ -148,25 +149,27 @@ static void tscProcessSubscriptionTimer(void *handle, void *tmrId) {
   TAOS_RES* res = taos_consume(pSub);
   if (res != NULL) {
     pSub->fp(pSub, res, pSub->param, 0);
-    // TODO: memory leak
   }
 
   taosTmrReset(tscProcessSubscriptionTimer, pSub->interval, pSub, tscTmr, &pSub->pTimer);
 }
 
 
-bool tscUpdateSubscription(STscObj* pObj, SSub* pSub) {
+int tscUpdateSubscription(STscObj* pObj, SSub* pSub) {
   int code = (uint8_t)tsParseSql(pSub->pSql, pObj->acctId, pObj->db, false);
   if (code != TSDB_CODE_SUCCESS) {
-    taos_unsubscribe(pSub);
-    return false;
+    tscError("failed to parse sql statement: %s", pSub->topic);
+    return 0;
   }
 
   int numOfMeters = 0;
   SSubscriptionProgress* progress = NULL;
 
-// ??? if there's more than one vnode
   SSqlCmd* pCmd = &pSub->pSql->cmd;
+  if (pCmd->command != TSDB_SQL_SELECT) {
+    tscError("only 'select' statement is allowed in subscription: %s", pSub->topic);
+    return 0;
+  }
 
   SMeterMetaInfo *pMeterMetaInfo = tscGetMeterMetaInfo(pCmd, 0);
   if (UTIL_METER_IS_NOMRAL_METER(pMeterMetaInfo)) {
@@ -177,14 +180,20 @@ bool tscUpdateSubscription(STscObj* pObj, SSub* pSub) {
     progress[0].key = tscGetSubscriptionProgress(pSub, uid);
   } else {
     SMetricMeta* pMetricMeta = pMeterMetaInfo->pMetricMeta;
-    SVnodeSidList *pVnodeSidList = tscGetVnodeSidList(pMetricMeta, pMeterMetaInfo->vnodeIndex);
-    numOfMeters = pVnodeSidList->numOfSids;
+    for (int32_t i = 0; i < pMetricMeta->numOfVnodes; i++) {
+      SVnodeSidList *pVnodeSidList = tscGetVnodeSidList(pMetricMeta, pMeterMetaInfo->vnodeIndex);
+      numOfMeters += pVnodeSidList->numOfSids;
+    }
     progress = calloc(numOfMeters, sizeof(SSubscriptionProgress));
-    for (int32_t i = 0; i < numOfMeters; ++i) {
-      SMeterSidExtInfo *pMeterInfo = tscGetMeterSidInfo(pVnodeSidList, i);
-      int64_t uid = pMeterInfo->uid;
-      progress[i].uid = uid;
-      progress[i].key = tscGetSubscriptionProgress(pSub, uid);
+    numOfMeters = 0;
+    for (int32_t i = 0; i < pMetricMeta->numOfVnodes; i++) {
+      SVnodeSidList *pVnodeSidList = tscGetVnodeSidList(pMetricMeta, pMeterMetaInfo->vnodeIndex);
+      for (int32_t j = 0; j < pVnodeSidList->numOfSids; j++) {
+        SMeterSidExtInfo *pMeterInfo = tscGetMeterSidInfo(pVnodeSidList, j);
+        int64_t uid = pMeterInfo->uid;
+        progress[numOfMeters].uid = uid;
+        progress[numOfMeters++].key = tscGetSubscriptionProgress(pSub, uid);
+      }
     }
     qsort(progress, numOfMeters, sizeof(SSubscriptionProgress), tscCompareSubscriptionProgress);
   }
@@ -193,33 +202,26 @@ bool tscUpdateSubscription(STscObj* pObj, SSub* pSub) {
   pSub->numOfMeters = numOfMeters;
   pSub->progress = progress;
 
-  // timestamp must in the output column
-  SFieldInfo* pFieldInfo = &pCmd->fieldsInfo;
-  tscFieldInfoSetValue(pFieldInfo, pFieldInfo->numOfOutputCols, TSDB_DATA_TYPE_TIMESTAMP, "_c0", TSDB_KEYSIZE);
-  tscSqlExprInsertEmpty(pCmd, pFieldInfo->numOfOutputCols - 1, TSDB_FUNC_PRJ);
-  tscFieldInfoUpdateVisible(pFieldInfo, pFieldInfo->numOfOutputCols - 1, false);
-  tscFieldInfoCalOffset(pCmd);
-
   pSub->lastSyncTime = taosGetTimestampMs();
 
-  return true;
+  return 1;
 }
 
 
-static void tscLoadSubscriptionProgress(SSub* pSub) {
+static int tscLoadSubscriptionProgress(SSub* pSub) {
   char buf[TSDB_MAX_SQL_LEN];
   sprintf(buf, "%s/subscribe/%s", dataDir, pSub->topic);
 
   FILE* fp = fopen(buf, "r");
   if (fp == NULL) {
     tscTrace("subscription progress file does not exist: %s", pSub->topic);
-    return true;
+    return 1;
   }
 
   if (fgets(buf, sizeof(buf), fp) == NULL) {
     tscTrace("invalid subscription progress file: %s", pSub->topic);
     fclose(fp);
-    return false;
+    return 0;
   }
 
   for (int i = 0; i < sizeof(buf); i++) {
@@ -233,13 +235,13 @@ static void tscLoadSubscriptionProgress(SSub* pSub) {
   if (strcmp(buf, pSub->pSql->sqlstr) != 0) {
     tscTrace("subscription sql statement mismatch: %s", pSub->topic);
     fclose(fp);
-    return false;
+    return 0;
   }
 
   if (fgets(buf, sizeof(buf), fp) == NULL || atoi(buf) < 0) {
     tscTrace("invalid subscription progress file: %s", pSub->topic);
     fclose(fp);
-    return false;
+    return 0;
   }
 
   int numOfMeters = atoi(buf);
@@ -248,7 +250,7 @@ static void tscLoadSubscriptionProgress(SSub* pSub) {
     if (fgets(buf, sizeof(buf), fp) == NULL) {
       fclose(fp);
       free(progress);
-      return false;
+      return 0;
     }
     int64_t uid, key;
     sscanf(buf, "uid=%" SCNd64 ",progress=%" SCNd64, &uid, &key);
@@ -261,7 +263,8 @@ static void tscLoadSubscriptionProgress(SSub* pSub) {
   qsort(progress, numOfMeters, sizeof(SSubscriptionProgress), tscCompareSubscriptionProgress);
   pSub->numOfMeters = numOfMeters;
   pSub->progress = progress;
-  return true;
+  tscTrace("subscription progress loaded, %d tables: %s", numOfMeters, pSub->topic);
+  return 1;
 }
 
 void tscSaveSubscriptionProgress(void* sub) {
@@ -291,7 +294,6 @@ void tscSaveSubscriptionProgress(void* sub) {
   fclose(fp);
 }
 
-
 TAOS_SUB *taos_subscribe(const char* topic, int restart, TAOS *taos, const char *sql, TAOS_SUBSCRIBE_CALLBACK fp, void *param, int interval) {
   STscObj* pObj = (STscObj*)taos;
   if (pObj == NULL || pObj->signature != pObj) {
@@ -313,6 +315,7 @@ TAOS_SUB *taos_subscribe(const char* topic, int restart, TAOS *taos, const char
   }
 
   if (!tscUpdateSubscription(pObj, pSub)) {
+    taos_unsubscribe(pSub, 1);
     return NULL;
   }
 
@@ -326,39 +329,55 @@ TAOS_SUB *taos_subscribe(const char* topic, int restart, TAOS *taos, const char
   return pSub;
 }
 
+void taos_free_result_imp(SSqlObj* pSql, int keepCmd);
+
 TAOS_RES *taos_consume(TAOS_SUB *tsub) {
   SSub *pSub = (SSub *)tsub;
   if (pSub == NULL) return NULL;
 
-  if (taosGetTimestampMs() - pSub->lastSyncTime > 30 * 60 * 1000) {
-    taos_query(pSub->taos, "reset query cache;");
-    // TODO: clear memory
-    if (!tscUpdateSubscription(pSub->taos, pSub)) return NULL;
-  }
-
   SSqlObj* pSql = pSub->pSql;
   SSqlRes *pRes = &pSql->res;
 
-  pRes->numOfRows = 1;
-  pRes->numOfTotal = 0;
-  pRes->qhandle = 0;
-  pSql->thandle = NULL;
-  pSql->cmd.command = TSDB_SQL_SELECT;
+  if (taosGetTimestampMs() - pSub->lastSyncTime > 10 * 1000) {
+    char* sqlstr = pSql->sqlstr;
+    pSql->sqlstr = NULL;
+    taos_free_result_imp(pSql, 0);
+    pSql->sqlstr = sqlstr;
+    taosClearDataCache(tscCacheHandle);
+    if (!tscUpdateSubscription(pSub->taos, pSub)) return NULL;
+  } else {
+    uint16_t type = pSql->cmd.type;
+    taos_free_result_imp(pSql, 1);
+    pRes->numOfRows = 1;
+    pRes->numOfTotal = 0;
+    pRes->qhandle = 0;
+    pSql->thandle = NULL;
+    pSql->cmd.command = TSDB_SQL_SELECT;
+    pSql->cmd.type = type;
+  }
 
   tscDoQuery(pSql);
   if (pRes->code != TSDB_CODE_SUCCESS) {
+    tscRemoveFromSqlList(pSql);
     return NULL;
   }
   return pSql;
 }
 
-void taos_unsubscribe(TAOS_SUB *tsub) {
+void taos_unsubscribe(TAOS_SUB *tsub, int keepProgress) {
   SSub *pSub = (SSub *)tsub;
   if (pSub == NULL || pSub->signature != pSub) return;
 
   if (pSub->pTimer != NULL) {
     taosTmrStop(pSub->pTimer);
   }
+
+  if (!keepProgress) {
+    char path[256];
+    sprintf(path, "%s/subscribe/%s", dataDir, pSub->topic);
+    remove(path);
+  }
+
   tscFreeSqlObj(pSub->pSql);
   free(pSub->progress);
   memset(pSub, 0, sizeof(*pSub));
diff --git a/src/client/src/tscUtil.c b/src/client/src/tscUtil.c
index 699c055249..f8a25828f5 100644
--- a/src/client/src/tscUtil.c
+++ b/src/client/src/tscUtil.c
@@ -376,6 +376,21 @@ void tscFreeSqlCmdData(SSqlCmd* pCmd) {
   }
 }
 
+void tscFreeSqlResult(SSqlObj* pSql) {
+  tfree(pSql->res.pRsp);
+  pSql->res.row = 0;
+  pSql->res.numOfRows = 0;
+  pSql->res.numOfTotal = 0;
+
+  pSql->res.numOfGroups = 0;
+  tfree(pSql->res.pGroupRec);
+
+  tscDestroyLocalReducer(pSql);
+
+  tscDestroyResPointerInfo(&pSql->res);
+  tfree(pSql->res.pColumnIndex);
+}
+
 void tscFreeSqlObjPartial(SSqlObj* pSql) {
   if (pSql == NULL || pSql->signature != pSql) {
     return;
@@ -399,20 +414,9 @@ void tscFreeSqlObjPartial(SSqlObj* pSql) {
   tfree(pSql->sqlstr);
   pthread_mutex_unlock(&pObj->mutex);
 
-  tfree(pSql->res.pRsp);
-  pSql->res.row = 0;
-  pSql->res.numOfRows = 0;
-  pSql->res.numOfTotal = 0;
-
-  pSql->res.numOfGroups = 0;
-  tfree(pSql->res.pGroupRec);
-
-  tscDestroyLocalReducer(pSql);
-
+  tscFreeSqlResult(pSql);
   tfree(pSql->pSubs);
   pSql->numOfSubs = 0;
-  tscDestroyResPointerInfo(pRes);
-  tfree(pSql->res.pColumnIndex);
 
   tscFreeSqlCmdData(pCmd);
   tscRemoveAllMeterMetaInfo(pCmd, false);
diff --git a/src/inc/taos.h b/src/inc/taos.h
index bdba644bb6..3574ec5b30 100644
--- a/src/inc/taos.h
+++ b/src/inc/taos.h
@@ -119,7 +119,7 @@ DLL_EXPORT void taos_fetch_row_a(TAOS_RES *res, void (*fp)(void *param, TAOS_RES
 typedef void (*TAOS_SUBSCRIBE_CALLBACK)(TAOS_SUB* tsub, TAOS_RES *res, void* param, int code);
 DLL_EXPORT TAOS_SUB *taos_subscribe(const char* topic, int restart, TAOS *taos, const char *sql, TAOS_SUBSCRIBE_CALLBACK fp, void *param, int interval);
 DLL_EXPORT TAOS_RES *taos_consume(TAOS_SUB *tsub);
-DLL_EXPORT void      taos_unsubscribe(TAOS_SUB *tsub);
+DLL_EXPORT void      taos_unsubscribe(TAOS_SUB *tsub, int keepProgress);
 
 DLL_EXPORT TAOS_STREAM *taos_open_stream(TAOS *taos, const char *sql, void (*fp)(void *param, TAOS_RES *, TAOS_ROW row),
                               int64_t stime, void *param, void (*callback)(void *));
diff --git a/tests/examples/c/subscribe.c b/tests/examples/c/subscribe.c
index c81246bac6..bcec3e61ec 100644
--- a/tests/examples/c/subscribe.c
+++ b/tests/examples/c/subscribe.c
@@ -29,7 +29,8 @@ int main(int argc, char *argv[]) {
   const char* user = "root";
   const char* passwd = "taosdata";
   const char* sql = "select * from meters;";
-  int async = 1, restart = 0;
+  const char* topic = "test-multiple";
+  int async = 1, restart = 0, keep = 1;
   TAOS_SUB* tsub = NULL;
 
   for (int i = 1; i < argc; i++) {
@@ -55,6 +56,11 @@ int main(int argc, char *argv[]) {
     }
     if (strcmp(argv[i], "-single") == 0) {
       sql = "select * from t0;";
+      topic = "test-single";
+      continue;
+    }
+    if (strcmp(argv[i], "-nokeep") == 0) {
+      keep = 0;
       continue;
     }
   }
@@ -69,9 +75,9 @@ int main(int argc, char *argv[]) {
   }
 
   if (async) {
-    tsub = taos_subscribe("test", restart, taos, sql, subscribe_callback, NULL, 1000);
+    tsub = taos_subscribe(topic, restart, taos, sql, subscribe_callback, NULL, 1000);
   } else {
-    tsub = taos_subscribe("test", restart, taos, sql, NULL, NULL, 0);
+    tsub = taos_subscribe(topic, restart, taos, sql, NULL, NULL, 0);
   }
 
   if (tsub == NULL) {
@@ -87,7 +93,7 @@ int main(int argc, char *argv[]) {
     getchar();
   }
 
-  taos_unsubscribe(tsub);
+  taos_unsubscribe(tsub, keep);
 
   return 0;
 }

From 592f210983d592e8d414df19abf8b5b0649462e3 Mon Sep 17 00:00:00 2001
From: localvar <localvar@hotmail.com>
Date: Sat, 4 Jan 2020 18:33:10 +0800
Subject: [PATCH 09/35] update java connector

---
 .../jni/com_taosdata_jdbc_TSDBJNIConnector.h  |   6 +-
 src/client/src/TSDBJNIConnector.c             | 135 +++++++++---------
 src/client/src/tscSub.c                       |  20 ++-
 src/inc/taos.h                                |   2 +-
 tests/examples/c/subscribe.c                  |   4 +-
 5 files changed, 87 insertions(+), 80 deletions(-)

diff --git a/src/client/jni/com_taosdata_jdbc_TSDBJNIConnector.h b/src/client/jni/com_taosdata_jdbc_TSDBJNIConnector.h
index 958252b4de..8dbe63d75a 100644
--- a/src/client/jni/com_taosdata_jdbc_TSDBJNIConnector.h
+++ b/src/client/jni/com_taosdata_jdbc_TSDBJNIConnector.h
@@ -135,7 +135,7 @@ JNIEXPORT jint JNICALL Java_com_taosdata_jdbc_TSDBJNIConnector_closeConnectionIm
  * Signature: (Ljava/lang/String;Ljava/lang/String;Ljava/lang/String;Ljava/lang/String;Ljava/lang/String;JI)J
  */
 JNIEXPORT jlong JNICALL Java_com_taosdata_jdbc_TSDBJNIConnector_subscribeImp
-  (JNIEnv *, jobject, jstring, jstring, jstring, jstring, jstring, jlong, jint);
+  (JNIEnv *, jobject, jlong, jboolean, jstring, jstring, jint);
 
 /*
  * Class:     com_taosdata_jdbc_TSDBJNIConnector
@@ -143,7 +143,7 @@ JNIEXPORT jlong JNICALL Java_com_taosdata_jdbc_TSDBJNIConnector_subscribeImp
  * Signature: (J)Lcom/taosdata/jdbc/TSDBResultSetRowData;
  */
 JNIEXPORT jobject JNICALL Java_com_taosdata_jdbc_TSDBJNIConnector_consumeImp
-  (JNIEnv *, jobject, jlong);
+  (JNIEnv *, jobject, jlong, jint);
 
 /*
  * Class:     com_taosdata_jdbc_TSDBJNIConnector
@@ -151,7 +151,7 @@ JNIEXPORT jobject JNICALL Java_com_taosdata_jdbc_TSDBJNIConnector_consumeImp
  * Signature: (J)V
  */
 JNIEXPORT void JNICALL Java_com_taosdata_jdbc_TSDBJNIConnector_unsubscribeImp
-  (JNIEnv *, jobject, jlong);
+  (JNIEnv *, jobject, jlong, jboolean);
 
 /*
  * Class:     com_taosdata_jdbc_TSDBJNIConnector
diff --git a/src/client/src/TSDBJNIConnector.c b/src/client/src/TSDBJNIConnector.c
index 9cec4f4b0f..228403c79d 100644
--- a/src/client/src/TSDBJNIConnector.c
+++ b/src/client/src/TSDBJNIConnector.c
@@ -20,6 +20,7 @@
 #include "tscJoinProcess.h"
 #include "tsclient.h"
 #include "tscUtil.h"
+#include "ttime.h"
 
 int __init = 0;
 
@@ -514,92 +515,42 @@ JNIEXPORT jint JNICALL Java_com_taosdata_jdbc_TSDBJNIConnector_closeConnectionIm
   }
 }
 
-JNIEXPORT jlong JNICALL Java_com_taosdata_jdbc_TSDBJNIConnector_subscribeImp(JNIEnv *env, jobject jobj, jstring jhost,
-                                                                             jstring juser, jstring jpass, jstring jdb,
-                                                                             jstring jtable, jlong jtime,
-                                                                             jint jperiod) {
-  TAOS_SUB *tsub;
-  jlong     sub = 0;
-  char *    host = NULL;
-  char *    user = NULL;
-  char *    pass = NULL;
-  char *    db = NULL;
-  char *    table = NULL;
-  int64_t   time = 0;
-  int       period = 0;
+JNIEXPORT jlong JNICALL Java_com_taosdata_jdbc_TSDBJNIConnector_subscribeImp(JNIEnv *env, jobject jobj, jlong con,
+                                                                             jboolean restart, jstring jtopic, jstring jsql, jint jinterval) {
+  jlong sub = 0;
+  TAOS *taos = (TAOS *)con;
+  char *topic = NULL;
+  char *sql = NULL;
 
   jniGetGlobalMethod(env);
   jniTrace("jobj:%p, in TSDBJNIConnector_subscribeImp", jobj);
 
-  if (jhost != NULL) {
-    host = (char *)(*env)->GetStringUTFChars(env, jhost, NULL);
+  if (jtopic != NULL) {
+    topic = (char *)(*env)->GetStringUTFChars(env, jtopic, NULL);
   }
-  if (juser != NULL) {
-    user = (char *)(*env)->GetStringUTFChars(env, juser, NULL);
-  }
-  if (jpass != NULL) {
-    pass = (char *)(*env)->GetStringUTFChars(env, jpass, NULL);
-  }
-  if (jdb != NULL) {
-    db = (char *)(*env)->GetStringUTFChars(env, jdb, NULL);
-  }
-  if (jtable != NULL) {
-    table = (char *)(*env)->GetStringUTFChars(env, jtable, NULL);
-  }
-  time = (int64_t)jtime;
-  period = (int)jperiod;
-
-  if (user == NULL) {
-    jniTrace("jobj:%p, user is null, use tsDefaultUser", jobj);
-    user = tsDefaultUser;
-  }
-  if (pass == NULL) {
-    jniTrace("jobj:%p, pass is null, use tsDefaultPass", jobj);
-    pass = tsDefaultPass;
+  if (jsql != NULL) {
+    sql = (char *)(*env)->GetStringUTFChars(env, jsql, NULL);
   }
 
-  jniTrace("jobj:%p, host:%s, user:%s, pass:%s, db:%s, table:%s, time:%d, period:%d", jobj, host, user, pass, db, table,
-           time, period);
-  tsub = taos_subscribe(host, user, pass, db, table, time, period);
+  TAOS_SUB *tsub = taos_subscribe(taos, (int)restart, topic, sql, NULL, NULL, jinterval);
   sub = (jlong)tsub;
 
   if (sub == 0) {
-    jniTrace("jobj:%p, failed to subscribe to db:%s, table:%s", jobj, db, table);
+    jniTrace("jobj:%p, failed to subscribe: topic:%s", jobj, jtopic);
   } else {
-    jniTrace("jobj:%p, successfully subscribe to db:%s, table:%s, sub:%ld, tsub:%p", jobj, db, table, sub, tsub);
+    jniTrace("jobj:%p, successfully subscribe: topic: %s", jobj, jtopic);
   }
 
-  if (host != NULL) (*env)->ReleaseStringUTFChars(env, jhost, host);
-  if (user != NULL && user != tsDefaultUser) (*env)->ReleaseStringUTFChars(env, juser, user);
-  if (pass != NULL && pass != tsDefaultPass) (*env)->ReleaseStringUTFChars(env, jpass, pass);
-  if (db != NULL) (*env)->ReleaseStringUTFChars(env, jdb, db);
-  if (table != NULL) (*env)->ReleaseStringUTFChars(env, jtable, table);
+  if (topic != NULL) (*env)->ReleaseStringUTFChars(env, jtopic, topic);
+  if (sql != NULL) (*env)->ReleaseStringUTFChars(env, jsql, sql);
 
   return sub;
 }
 
-JNIEXPORT jobject JNICALL Java_com_taosdata_jdbc_TSDBJNIConnector_consumeImp(JNIEnv *env, jobject jobj, jlong sub) {
-  jniTrace("jobj:%p, in TSDBJNIConnector_consumeImp, sub:%ld", jobj, sub);
-
-  TAOS_SUB *  tsub = (TAOS_SUB *)sub;
-  TAOS_ROW    row = taos_consume(tsub);
-  TAOS_FIELD *fields = taos_fetch_subfields(tsub);
-  int         num_fields = taos_subfields_count(tsub);
-
-  jniGetGlobalMethod(env);
-
-  jniTrace("jobj:%p, check fields:%p, num_fields=%d", jobj, fields, num_fields);
-
+static jobject convert_one_row(JNIEnv *env, TAOS_ROW row, TAOS_FIELD* fields, int num_fields) {
   jobject rowobj = (*env)->NewObject(env, g_rowdataClass, g_rowdataConstructor, num_fields);
   jniTrace("created a rowdata object, rowobj:%p", rowobj);
 
-  if (row == NULL) {
-    jniTrace("jobj:%p, tsub:%p, fields size is %d, fetch row to the end", jobj, tsub, num_fields);
-    return NULL;
-  }
-
-  char tmp[TSDB_MAX_BYTES_PER_ROW] = {0};
-
   for (int i = 0; i < num_fields; i++) {
     if (row[i] == NULL) {
       continue;
@@ -634,6 +585,7 @@ JNIEXPORT jobject JNICALL Java_com_taosdata_jdbc_TSDBJNIConnector_consumeImp(JNI
       }
         break;
       case TSDB_DATA_TYPE_BINARY: {
+        char tmp[TSDB_MAX_BYTES_PER_ROW] = {0};
         strncpy(tmp, row[i], (size_t) fields[i].bytes);  // handle the case that terminated does not exist
         (*env)->CallVoidMethod(env, rowobj, g_rowdataSetStringFp, i, (*env)->NewStringUTF(env, tmp));
 
@@ -642,7 +594,7 @@ JNIEXPORT jobject JNICALL Java_com_taosdata_jdbc_TSDBJNIConnector_consumeImp(JNI
       }
       case TSDB_DATA_TYPE_NCHAR:
         (*env)->CallVoidMethod(env, rowobj, g_rowdataSetByteArrayFp, i,
-                               jniFromNCharToByteArray(env, (char*)row[i], fields[i].bytes));
+                              jniFromNCharToByteArray(env, (char*)row[i], fields[i].bytes));
         break;
       case TSDB_DATA_TYPE_TIMESTAMP:
         (*env)->CallVoidMethod(env, rowobj, g_rowdataSetTimestampFp, i, (jlong) * ((int64_t *)row[i]));
@@ -651,13 +603,56 @@ JNIEXPORT jobject JNICALL Java_com_taosdata_jdbc_TSDBJNIConnector_consumeImp(JNI
         break;
     }
   }
-  jniTrace("jobj:%p, rowdata retrieved, rowobj:%p", jobj, rowobj);
   return rowobj;
 }
 
-JNIEXPORT void JNICALL Java_com_taosdata_jdbc_TSDBJNIConnector_unsubscribeImp(JNIEnv *env, jobject jobj, jlong sub) {
+JNIEXPORT jobject JNICALL Java_com_taosdata_jdbc_TSDBJNIConnector_consumeImp(JNIEnv *env, jobject jobj, jlong sub, jint timeout) {
+  jniTrace("jobj:%p, in TSDBJNIConnector_consumeImp, sub:%ld", jobj, sub);
+  jniGetGlobalMethod(env);
+
   TAOS_SUB *tsub = (TAOS_SUB *)sub;
-  taos_unsubscribe(tsub);
+  jobject   rows = (*env)->NewObject(env, g_arrayListClass, g_arrayListConstructFp);
+
+  int64_t start = taosGetTimestampMs();
+  int count = 0;
+
+  while (true) {
+    TAOS_RES *  res = taos_consume(tsub);
+    if (res == NULL) {
+      jniError("jobj:%p, tsub:%p, taos_consume returns NULL", jobj, tsub);
+      return NULL;
+    }
+
+    TAOS_FIELD *fields = taos_fetch_fields(res);
+    int         num_fields = taos_num_fields(res);
+    while (true) {
+      TAOS_ROW row = taos_fetch_row(res);
+      if (row == NULL) {
+        break;
+      }
+      jobject rowobj = convert_one_row(env, row, fields, num_fields);
+      (*env)->CallBooleanMethod(env, rows, g_arrayListAddFp, rowobj);
+      count++;
+    }
+
+    if (count > 0) {
+      break;
+    }
+    if (timeout == -1) {
+      continue;
+    }
+    if (((int)(taosGetTimestampMs() - start)) >= timeout) {
+      jniTrace("jobj:%p, sub:%ld, timeout", jobj, sub);
+      break;
+    }
+  }
+
+  return rows;
+}
+
+JNIEXPORT void JNICALL Java_com_taosdata_jdbc_TSDBJNIConnector_unsubscribeImp(JNIEnv *env, jobject jobj, jlong sub, jboolean keepProgress) {
+  TAOS_SUB *tsub = (TAOS_SUB *)sub;
+  taos_unsubscribe(tsub, keepProgress);
 }
 
 JNIEXPORT jint JNICALL Java_com_taosdata_jdbc_TSDBJNIConnector_validateCreateTableSqlImp(JNIEnv *env, jobject jobj,
diff --git a/src/client/src/tscSub.c b/src/client/src/tscSub.c
index b2c332deff..8293378abf 100644
--- a/src/client/src/tscSub.c
+++ b/src/client/src/tscSub.c
@@ -35,6 +35,7 @@ typedef struct SSubscriptionProgress {
 typedef struct SSub {
   char                    topic[32];
   int64_t                 lastSyncTime;
+  int64_t                 lastConsumeTime;
   void *                  signature;
   TAOS *                  taos;
   void *                  pTimer;
@@ -128,6 +129,7 @@ static SSub* tscCreateSubscription(STscObj* pObj, const char* topic, const char*
   pSub->pSql = pSql;
   pSub->signature = pSub;
   strncpy(pSub->topic, topic, sizeof(pSub->topic));
+  pSub->topic[sizeof(pSub->topic) - 1] = 0;
   return pSub;
 
 failed:
@@ -294,7 +296,7 @@ void tscSaveSubscriptionProgress(void* sub) {
   fclose(fp);
 }
 
-TAOS_SUB *taos_subscribe(const char* topic, int restart, TAOS *taos, const char *sql, TAOS_SUBSCRIBE_CALLBACK fp, void *param, int interval) {
+TAOS_SUB *taos_subscribe(TAOS *taos, int restart, const char* topic, const char *sql, TAOS_SUBSCRIBE_CALLBACK fp, void *param, int interval) {
   STscObj* pObj = (STscObj*)taos;
   if (pObj == NULL || pObj->signature != pObj) {
     globalCode = TSDB_CODE_DISCONNECTED;
@@ -319,11 +321,11 @@ TAOS_SUB *taos_subscribe(const char* topic, int restart, TAOS *taos, const char
     return NULL;
   }
 
+  pSub->interval = interval;
   if (fp != NULL) {
     pSub->fp = fp;
-    pSub->interval = interval;
     pSub->param = param;
-    taosTmrReset(tscProcessSubscriptionTimer, 0, pSub, tscTmr, &pSub->pTimer);
+    taosTmrReset(tscProcessSubscriptionTimer, interval, pSub, tscTmr, &pSub->pTimer);
   }
 
   return pSub;
@@ -338,7 +340,14 @@ TAOS_RES *taos_consume(TAOS_SUB *tsub) {
   SSqlObj* pSql = pSub->pSql;
   SSqlRes *pRes = &pSql->res;
 
-  if (taosGetTimestampMs() - pSub->lastSyncTime > 10 * 1000) {
+  if (pSub->pTimer == NULL) {
+    int duration = (int)(taosGetTimestampMs() - pSub->lastConsumeTime);
+    if (duration < pSub->interval) {
+      taosMsleep(pSub->interval - (int32_t)duration);
+    }
+  }
+
+  if (taosGetTimestampMs() - pSub->lastSyncTime > 10 * 60 * 1000) {
     char* sqlstr = pSql->sqlstr;
     pSql->sqlstr = NULL;
     taos_free_result_imp(pSql, 0);
@@ -356,11 +365,14 @@ TAOS_RES *taos_consume(TAOS_SUB *tsub) {
     pSql->cmd.type = type;
   }
 
+
   tscDoQuery(pSql);
   if (pRes->code != TSDB_CODE_SUCCESS) {
     tscRemoveFromSqlList(pSql);
     return NULL;
   }
+
+  pSub->lastConsumeTime = taosGetTimestampMs();
   return pSql;
 }
 
diff --git a/src/inc/taos.h b/src/inc/taos.h
index 3574ec5b30..d9db79fbcb 100644
--- a/src/inc/taos.h
+++ b/src/inc/taos.h
@@ -117,7 +117,7 @@ DLL_EXPORT void taos_fetch_rows_a(TAOS_RES *res, void (*fp)(void *param, TAOS_RE
 DLL_EXPORT void taos_fetch_row_a(TAOS_RES *res, void (*fp)(void *param, TAOS_RES *, TAOS_ROW row), void *param);
 
 typedef void (*TAOS_SUBSCRIBE_CALLBACK)(TAOS_SUB* tsub, TAOS_RES *res, void* param, int code);
-DLL_EXPORT TAOS_SUB *taos_subscribe(const char* topic, int restart, TAOS *taos, const char *sql, TAOS_SUBSCRIBE_CALLBACK fp, void *param, int interval);
+DLL_EXPORT TAOS_SUB *taos_subscribe(TAOS* taos, int restart, const char* topic, const char *sql, TAOS_SUBSCRIBE_CALLBACK fp, void *param, int interval);
 DLL_EXPORT TAOS_RES *taos_consume(TAOS_SUB *tsub);
 DLL_EXPORT void      taos_unsubscribe(TAOS_SUB *tsub, int keepProgress);
 
diff --git a/tests/examples/c/subscribe.c b/tests/examples/c/subscribe.c
index bcec3e61ec..80efa71dc2 100644
--- a/tests/examples/c/subscribe.c
+++ b/tests/examples/c/subscribe.c
@@ -75,9 +75,9 @@ int main(int argc, char *argv[]) {
   }
 
   if (async) {
-    tsub = taos_subscribe(topic, restart, taos, sql, subscribe_callback, NULL, 1000);
+    tsub = taos_subscribe(taos, restart, topic, sql, subscribe_callback, NULL, 1000);
   } else {
-    tsub = taos_subscribe(topic, restart, taos, sql, NULL, NULL, 0);
+    tsub = taos_subscribe(taos, restart, topic, sql, NULL, NULL, 0);
   }
 
   if (tsub == NULL) {

From 23527898e75932ff292e7a4f9602be1c6dc3f2f1 Mon Sep 17 00:00:00 2001
From: localvar <localvar@hotmail.com>
Date: Mon, 6 Jan 2020 10:43:15 +0800
Subject: [PATCH 10/35] fix issue in single meter subscription.

---
 src/system/detail/src/vnodeShell.c | 6 +++++-
 tests/examples/c/subscribe.c       | 5 +++++
 2 files changed, 10 insertions(+), 1 deletion(-)

diff --git a/src/system/detail/src/vnodeShell.c b/src/system/detail/src/vnodeShell.c
index 66cc16d9df..0b7420664d 100644
--- a/src/system/detail/src/vnodeShell.c
+++ b/src/system/detail/src/vnodeShell.c
@@ -494,7 +494,11 @@ void vnodeExecuteRetrieveReq(SSchedMsg *pSched) {
     pMsg += sizeof(int32_t);
     *((int64_t*)pMsg) = htobe64(pQInfo->pObj->uid);
     pMsg += sizeof(int64_t);
-    *((TSKEY*)pMsg) = htobe64(pQInfo->query.lastKey);
+    if (pQInfo->pointsRead > 0) {
+      *((TSKEY*)pMsg) = htobe64(pQInfo->query.lastKey + 1);
+    } else {
+      *((TSKEY*)pMsg) = htobe64(pQInfo->query.lastKey);
+    }
     pMsg += sizeof(TSKEY);
   }
 
diff --git a/tests/examples/c/subscribe.c b/tests/examples/c/subscribe.c
index 80efa71dc2..a36de8e010 100644
--- a/tests/examples/c/subscribe.c
+++ b/tests/examples/c/subscribe.c
@@ -63,6 +63,11 @@ int main(int argc, char *argv[]) {
       keep = 0;
       continue;
     }
+    if (strncmp(argv[i], "-sql=", 5) == 0) {
+      sql = argv[i] + 5;
+      topic = "test-custom";
+      continue;
+    }
   }
 
   // init TAOS

From d7a8b0cb2d462249b6bb7a3a01b7f826c78482be Mon Sep 17 00:00:00 2001
From: localvar <localvar@hotmail.com>
Date: Mon, 6 Jan 2020 15:09:24 +0800
Subject: [PATCH 11/35] tbase-915: documentation for subscription

---
 .../webdocs/markdowndocs/Connector.md         | 34 ++++++++++++-------
 .../markdowndocs/advanced features-ch.md      | 21 ++----------
 .../webdocs/markdowndocs/connector-ch.md      | 33 +++++++++++-------
 3 files changed, 44 insertions(+), 44 deletions(-)

diff --git a/documentation/webdocs/markdowndocs/Connector.md b/documentation/webdocs/markdowndocs/Connector.md
index 46a2b04daa..caedff4436 100644
--- a/documentation/webdocs/markdowndocs/Connector.md
+++ b/documentation/webdocs/markdowndocs/Connector.md
@@ -175,26 +175,34 @@ TDengine provides APIs for continuous query driven by time, which run queries pe
 
 ### C/C++ subscription API
 
-For the time being, TDengine supports subscription on one table. It is implemented through periodic pulling from a TDengine server. 
+For the time being, TDengine supports subscription on one or multiple tables. It is implemented through periodic pulling from a TDengine server. 
 
-- `TAOS_SUB *taos_subscribe(char *host, char *user, char *pass, char      *db, char *table, int64_t time, int mseconds)`
-  The API is used to start a subscription session by given a handle. The parameters required are _host_ (IP address of a TDenginer server), _user_ (username), _pass_ (password), _db_ (database to use), _table_ (table name to subscribe), _time_ (start time to subscribe, 0 for now), _mseconds_ (pulling period). If failed to open a subscription session, a _NULL_ pointer is returned.
+* `TAOS_SUB *taos_subscribe(TAOS* taos, int restart, const char* topic, const char *sql, TAOS_SUBSCRIBE_CALLBACK fp, void *param, int interval)`
 
+  The API is used to start a subscription session, it returns the subscription object on success and `NULL` in case of failure, the parameters are:
+  * **taos**: The database connnection, which must be established already.
+  * **restart**: `Zero` to continue a subscription if it already exits, other value to start from the beginning.
+  * **topic**: The unique identifier of a subscription.
+  * **sql**: A sql statement for data query, it can only be a `select` statement, can only query for raw data, and can only query data in ascending order of the timestamp field.
+  * **fp**: A callback function to receive query result, only used in asynchronization mode and should be `NULL` in synchronization mode, please refer below for its prototype.
+  * **param**: User provided additional parameter for the callback function.
+  * **interval**: Pulling interval in millisecond. Under asynchronization mode, API will call the callback function `fp` in this interval, system performance will be impacted if this interval is too short. Under synchronization mode, if the duration between two call to `taos_consume` is less than this interval, the second call blocks until the duration exceed this interval.
 
-- `TAOS_ROW taos_consume(TAOS_SUB *tsub)`
-  The API used to get the new data from a TDengine server. It should be put in an infinite loop. The parameter _tsub_ is the handle returned by _taos_subscribe_. If new data are updated, the API will return a row of the result. Otherwise, the API is blocked until new data arrives. If _NULL_ pointer is returned, it means an error occurs.
+* `typedef void (*TAOS_SUBSCRIBE_CALLBACK)(TAOS_SUB* tsub, TAOS_RES *res, void* param, int code)`
 
+  Prototype of the callback function, the parameters are:
+  * tsub: The subscription object.
+  * res: The query result.
+  * param: User provided additional parameter when calling `taos_subscribe`.
+  * code: Error code in case of failures.
 
-- `void taos_unsubscribe(TAOS_SUB *tsub)`
-  Stop a subscription session by the handle returned by _taos_subscribe_.
+* `TAOS_RES *taos_consume(TAOS_SUB *tsub)`
 
+  The API used to get the new data from a TDengine server. It should be put in an loop. The parameter `tsub` is the handle returned by `taos_subscribe`. This API should only be called in synchronization mode. If the duration between two call to `taos_consume` is less than pulling interval, the second call blocks until the duration exceed the interval. The API returns the new rows if new data arrives, or empty rowset otherwise, and if there's an error, it returns `NULL`.
+  
+* `void taos_unsubscribe(TAOS_SUB *tsub, int keepProgress)`
 
-- `int taos_num_subfields(TAOS_SUB *tsub)`
-  The API used to get the number of fields in a row.
-
-
-- `TAOS_FIELD *taos_fetch_subfields(TAOS_SUB *tsub)`
-  The API used to get the description of each column.
+  Stop a subscription session by the handle returned by `taos_subscribe`. If `keepProgress` is **not** zero, the subscription progress information is kept and can be reused in later call to `taos_subscribe`, the information is removed otherwise.
 
 ##  Java Connector
 
diff --git a/documentation/webdocs/markdowndocs/advanced features-ch.md b/documentation/webdocs/markdowndocs/advanced features-ch.md
index 14a2801209..4d01eaf364 100644
--- a/documentation/webdocs/markdowndocs/advanced features-ch.md	
+++ b/documentation/webdocs/markdowndocs/advanced features-ch.md	
@@ -63,28 +63,11 @@ CREATE TABLE QUERY_RES
 ## 数据订阅(Publisher/Subscriber)
 基于数据天然的时间序列特性，TDengine的数据写入（insert）与消息系统的数据发布（pub）逻辑上一致，均可视为系统中插入一条带时间戳的新记录。同时，TDengine在内部严格按照数据时间序列单调递增的方式保存数据。本质上来说，TDengine中里每一张表均可视为一个标准的消息队列。
 
-TDengine内嵌支持轻量级的消息订阅与推送服务。使用系统提供的API，用户可订阅数据库中的某一张表（或超级表）。订阅的逻辑和操作状态的维护均是由客户端完成，客户端定时轮询服务器是否有新的记录到达，有新的记录到达就会将结果反馈到客户。
+TDengine内嵌支持轻量级的消息订阅与推送服务。使用系统提供的API，用户可使用普通查询语句订阅数据库中的一张或多张表。订阅的逻辑和操作状态的维护均是由客户端完成，客户端定时轮询服务器是否有新的记录到达，有新的记录到达就会将结果反馈到客户。
 
 TDengine的订阅与推送服务的状态是客户端维持，TDengine服务器并不维持。因此如果应用重启，从哪个时间点开始获取最新数据，由应用决定。
 
-#### API说明
-
-使用订阅的功能，主要API如下：
-
-<ul>
-<li><p><code>TAOS_SUB *taos_subscribe(char *host, char *user, char *pass, char *db, char *table, int64_t time, int mseconds)</code></p><p>该函数负责启动订阅服务。其中参数说明：</p></li><ul>
-<li><p>host：主机IP地址</p></li>
-<li><p>user：数据库登录用户名</p></li>
-<li><p>pass：密码</p></li>
-<li><p>db：数据库名称</p></li>
-<li><p>table：(超级) 表的名称</p></li>
-<li><p>time：启动时间，Unix Epoch时间，单位为毫秒。从1970年1月1日起计算的毫秒数。如果设为0，表示从当前时间开始订阅</p></li>
-<li><p>mseconds：查询数据库更新的时间间隔，单位为毫秒。一般设置为1000毫秒。返回值为指向TDengine_SUB 结构的指针，如果返回为空，表示失败。</p></li>
-</ul><li><p><code>TAOS_ROW taos_consume(TAOS_SUB *tsub)</code>
-</p><p>该函数用来获取订阅的结果，用户应用程序将其置于一个无限循环语句。如果数据库有新记录到达，该API将返回该最新的记录。如果没有新的记录，该API将阻塞。如果返回值为空，说明系统出错。参数说明：</p></li><ul><li><p>tsub：taos_subscribe的结构体指针。</p></li></ul><li><p><code>void taos_unsubscribe(TAOS_SUB *tsub)</code></p><p>取消订阅。应用程序退出时，务必调用该函数以避免资源泄露。</p></li>
-<li><p><code>int taos_num_subfields(TAOS_SUB *tsub)</code></p><p>获取返回的一行记录中数据包含多少列。</p></li>
-<li><p><code>TAOS_FIELD *taos_fetch_subfields(TAOS_SUB *tsub)</code></p><p>获取每列数据的属性（数据类型、名字、长度），与taos_num_subfileds配合使用，可解析返回的每行数据。</p></li></ul>
-示例代码：请看安装包中的的示范程序
+订阅相关API请见 [连接器](https://www.taosdata.com/cn/documentation/connector/)。
 
 ## 缓存 (Cache)
 TDengine采用时间驱动缓存管理策略（First-In-First-Out，FIFO），又称为写驱动的缓存管理机制。这种策略有别于读驱动的数据缓存模式（Least-Recent-Use，LRU），直接将最近写入的数据保存在系统的缓存中。当缓存达到临界值的时候，将最早的数据批量写入磁盘。一般意义上来说，对于物联网数据的使用，用户最为关心最近产生的数据，即当前状态。TDengine充分利用了这一特性，将最近到达的（当前状态）数据保存在缓存中。
diff --git a/documentation/webdocs/markdowndocs/connector-ch.md b/documentation/webdocs/markdowndocs/connector-ch.md
index 23bc6a9f6c..c9eaa8e63b 100644
--- a/documentation/webdocs/markdowndocs/connector-ch.md
+++ b/documentation/webdocs/markdowndocs/connector-ch.md
@@ -164,27 +164,36 @@ TDengine提供时间驱动的实时流式计算API。可以每隔一指定的时
 
 ### C/C++ 数据订阅接口
 
-订阅API目前支持订阅一张表，并通过定期轮询的方式不断获取写入表中的最新数据。 
+订阅API目前支持订阅一张或多张表，并通过定期轮询的方式不断获取写入表中的最新数据。 
 
-- `TAOS_SUB *taos_subscribe(char *host, char *user, char *pass, char *db, char *table, int64_t time, int mseconds)`
+* `TAOS_SUB *taos_subscribe(TAOS* taos, int restart, const char* topic, const char *sql, TAOS_SUBSCRIBE_CALLBACK fp, void *param, int interval)`
 
-  该API用来启动订阅，需要提供的参数包含：TDengine管理主节点的IP地址、用户名、密码、数据库、数据库表的名字；time是开始订阅消息的时间，是从1970年1月1日起计算的毫秒数，为长整型, 如果设为0，表示从当前时间开始订阅；mseconds为查询数据库更新的时间间隔，单位为毫秒，建议设为1000毫秒。返回值为一指向TDengine_SUB结构的指针，如果返回为空，表示失败。
+  该函数负责启动订阅服务，成功时返回订阅对象，失败时返回 `NULL`，其参数为：
+  * taos：已经建立好的数据库连接
+  * restart：如果订阅已经存在，是重新开始，还是继续之前的订阅
+  * topic：订阅的主题（即名称），此参数是订阅的唯一标识
+  * sql：订阅的查询语句，此语句只能是 `select` 语句，只应查询原始数据，只能按时间正序查询数据
+  * fp：收到查询结果时的回调函数（稍后介绍函数原型），只在异步调用时使用，同步调用时此参数应该传 `NULL`
+  * param：调用回调函数时的附加参数，系统API将其原样传递到回调函数，不进行任何处理
+  * interval：轮询周期，单位为毫秒。异步调用时，将根据此参数周期性的调用回调函数，为避免对系统性能造成影响，不建议将此参数设置的过小；同步调用时，如两次调用`taos_consume`的间隔小于此周期，API将会阻塞，直到时间间隔超过此周期。
 
-- `TAOS_ROW taos_consume(TAOS_SUB *tsub)`
+* `typedef void (*TAOS_SUBSCRIBE_CALLBACK)(TAOS_SUB* tsub, TAOS_RES *res, void* param, int code)`
 
-  该API用来获取最新消息，应用程序一般会将其置于一个无限循环语句中。其中参数tsub是taos_subscribe的返回值。如果数据库有新的记录，该API将返回，返回参数是一行记录。如果没有新的记录，该API将阻塞。如果返回值为空，说明系统出错，需要检查系统是否还在正常运行。
+  异步模式下，回调函数的原型，其参数为：
+  * tsub：订阅对象
+  * res：查询结果集，注意结果集中可能没有记录
+  * param：调用 `taos_subscribe`时客户程序提供的附加参数
+  * code：错误码
 
-- `void taos_unsubscribe(TAOS_SUB *tsub)`
 
-  该API用于取消订阅，参数tsub是taos_subscribe的返回值。应用程序退出时，需要调用该API，否则有资源泄露。
+* `TAOS_RES *taos_consume(TAOS_SUB *tsub)`
 
-- `int taos_num_subfields(TAOS_SUB *tsub)`
+  同步模式下，该函数用来获取订阅的结果。 用户应用程序将其置于一个循环之中。 如两次调用`taos_consume`的间隔小于订阅的轮询周期，API将会阻塞，直到时间间隔超过此周期。 如果数据库有新记录到达，该API将返回该最新的记录，否则返回一个没有记录的空结果集。 如果返回值为 `NULL`，说明系统出错。 异步模式下，用户程序不应调用此API。
 
-  该API用来获取返回的一排数据中数据的列数
+* `void taos_unsubscribe(TAOS_SUB *tsub, int keepProgress)`
 
-- `TAOS_FIELD *taos_fetch_subfields(TAOS_SUB *tsub)`
+  取消订阅。 如参数 `keepProgress` 不为0，API会保留订阅的进度信息，后续调用 `taos_subscribe` 时可以基于此进度继续；否则将删除进度信息，后续只能重新开始读取数据。
 
-  该API用来获取每列数据的属性（数据类型、名字、字节数），与taos_num_subfields配合使用，可用来解析返回的一排数据。
 
 ##  Java Connector
 
@@ -205,7 +214,7 @@ TDengine 的 JDBC 驱动实现尽可能的与关系型数据库驱动保持一
 * TDengine 不提供针对单条数据记录的删除和修改的操作，驱动中也没有支持相关方法。
 * 由于不支持删除和修改，所以也不支持事务操作。
 * 目前不支持表间的 union 操作。
-* 目前不支持嵌套查询(nested query)，`对每个 Connection 的实例，至多只能有一个打开的 ResultSet 实例；如果在 ResultSet还没关闭的情况下执行了新的查询，TSDBJDBCDriver 则会自动关闭上一个 ResultSet`。
+* 目前不支持嵌套查询(nested query)，对每个 Connection 的实例，至多只能有一个打开的 ResultSet 实例；如果在 ResultSet还没关闭的情况下执行了新的查询，TSDBJDBCDriver 则会自动关闭上一个 ResultSet。
 
 
 ## TAOS-JDBCDriver 版本以及支持的 TDengine 版本和 JDK 版本

From 76ade609947a2b6e2d6ed7e95c6efa03c65a52a5 Mon Sep 17 00:00:00 2001
From: localvar <localvar@hotmail.com>
Date: Wed, 8 Jan 2020 10:22:40 +0800
Subject: [PATCH 12/35] tbase-916

---
 src/client/src/tscSub.c      |   2 +-
 tests/examples/c/subscribe.c | 104 ++++++++++++++++++++++++++++++++++-
 2 files changed, 103 insertions(+), 3 deletions(-)

diff --git a/src/client/src/tscSub.c b/src/client/src/tscSub.c
index 8293378abf..225d3f0e6f 100644
--- a/src/client/src/tscSub.c
+++ b/src/client/src/tscSub.c
@@ -33,10 +33,10 @@ typedef struct SSubscriptionProgress {
 } SSubscriptionProgress;
 
 typedef struct SSub {
+  void *                  signature;
   char                    topic[32];
   int64_t                 lastSyncTime;
   int64_t                 lastConsumeTime;
-  void *                  signature;
   TAOS *                  taos;
   void *                  pTimer;
   SSqlObj *               pSql;
diff --git a/tests/examples/c/subscribe.c b/tests/examples/c/subscribe.c
index a36de8e010..078929a9b8 100644
--- a/tests/examples/c/subscribe.c
+++ b/tests/examples/c/subscribe.c
@@ -5,7 +5,7 @@
 #include <stdlib.h>
 #include <string.h>
 #include <taos.h>  // include TDengine header file
-
+#include <unistd.h>
 
 void print_result(TAOS_RES* res) {
   TAOS_ROW    row;
@@ -24,13 +24,102 @@ void subscribe_callback(TAOS_SUB* tsub, TAOS_RES *res, void* param, int code) {
 }
 
 
+void check_row_count(int line, TAOS_RES* res, int expected) {
+  int actual = 0;
+  TAOS_ROW    row;
+  while ((row = taos_fetch_row(res))) {
+    actual++;
+  }
+  if (actual != expected) {
+    printf("line %d: row count mismatch, expected: %d, actual: %d\n", line, expected, actual);
+  } else {
+    printf("line %d: %d rows consumed as expected\n", line, actual);
+  }
+}
+
+void run_test(TAOS* taos) {
+  taos_query(taos, "drop database test;");
+  
+  usleep(100000);
+  taos_query(taos, "create database test;");
+  usleep(100000);
+  taos_query(taos, "use test;");
+  usleep(100000);
+  taos_query(taos, "create table meters(ts timestamp, a int, b binary(20)) tags(loc binary(20), area int);");
+
+  taos_query(taos, "insert into t0 using meters tags('beijing', 0) values('2020-01-01 00:00:00.000', 0, 'china');");
+  taos_query(taos, "insert into t0 using meters tags('beijing', 0) values('2020-01-01 00:01:00.000', 0, 'china');");
+  taos_query(taos, "insert into t0 using meters tags('beijing', 0) values('2020-01-01 00:02:00.000', 0, 'china');");
+  taos_query(taos, "insert into t1 using meters tags('shanghai', 0) values('2020-01-01 00:00:00.000', 0, 'china');");
+  taos_query(taos, "insert into t1 using meters tags('shanghai', 0) values('2020-01-01 00:01:00.000', 0, 'china');");
+  taos_query(taos, "insert into t1 using meters tags('shanghai', 0) values('2020-01-01 00:02:00.000', 0, 'china');");
+  taos_query(taos, "insert into t1 using meters tags('shanghai', 0) values('2020-01-01 00:03:00.000', 0, 'china');");
+  taos_query(taos, "insert into t2 using meters tags('london', 0) values('2020-01-01 00:00:00.000', 0, 'UK');");
+  taos_query(taos, "insert into t2 using meters tags('london', 0) values('2020-01-01 00:01:00.000', 0, 'UK');");
+  taos_query(taos, "insert into t2 using meters tags('london', 0) values('2020-01-01 00:01:01.000', 0, 'UK');");
+  taos_query(taos, "insert into t2 using meters tags('london', 0) values('2020-01-01 00:01:02.000', 0, 'UK');");
+
+  // super tables subscription
+
+  TAOS_SUB* tsub = taos_subscribe(taos, 0, "test", "select * from meters;", NULL, NULL, 0);
+  TAOS_RES* res = taos_consume(tsub);
+  check_row_count(__LINE__, res, 11);
+
+  res = taos_consume(tsub);
+  check_row_count(__LINE__, res, 0);
+
+  taos_query(taos, "insert into t2 using meters tags('london', 0) values('2020-01-01 00:01:02.001', 0, 'UK');");
+  taos_query(taos, "insert into t1 using meters tags('london', 0) values('2020-01-01 00:03:00.001', 0, 'UK');");
+  res = taos_consume(tsub);
+  check_row_count(__LINE__, res, 2);
+
+  taos_query(taos, "insert into t1 using meters tags('shanghai', 0) values('2020-01-01 00:03:00.002', 0, 'china');");
+  res = taos_consume(tsub);
+  check_row_count(__LINE__, res, 1);
+
+  // keep progress information and continue previous subscription
+  taos_unsubscribe(tsub, 1);
+  taos_query(taos, "insert into t0 using meters tags('beijing', 0) values('2020-01-01 00:03:00.000', 0, 'china');");
+  tsub = taos_subscribe(taos, 1, "test", "select * from meters;", NULL, NULL, 0);
+  res = taos_consume(tsub);
+  check_row_count(__LINE__, res, 15);
+
+  // don't keep progress information and continue previous subscription
+  taos_unsubscribe(tsub, 0);
+  tsub = taos_subscribe(taos, 0, "test", "select * from meters;", NULL, NULL, 0);
+  res = taos_consume(tsub);
+  check_row_count(__LINE__, res, 15);
+
+  // single meter subscription
+
+  taos_unsubscribe(tsub, 0);
+  tsub = taos_subscribe(taos, 0, "test", "select * from t0;", NULL, NULL, 0);
+  res = taos_consume(tsub);
+  check_row_count(__LINE__, res, 4);
+
+  res = taos_consume(tsub);
+  check_row_count(__LINE__, res, 0);
+
+  taos_query(taos, "insert into t0 using meters tags('beijing', 0) values('2020-01-01 00:03:00.001', 0, 'china');");
+  res = taos_consume(tsub);
+  check_row_count(__LINE__, res, 1);
+
+  taos_query(taos, "insert into t0 using meters tags('beijing', 0) values('2020-01-01 00:03:00.002', 0, 'china');");
+  taos_query(taos, "insert into t0 using meters tags('beijing', 0) values('2020-01-01 00:04:00.000', 0, 'china');");
+  res = taos_consume(tsub);
+  check_row_count(__LINE__, res, 2);
+
+  taos_unsubscribe(tsub, 0);
+}
+
+
 int main(int argc, char *argv[]) {
   const char* host = "127.0.0.1";
   const char* user = "root";
   const char* passwd = "taosdata";
   const char* sql = "select * from meters;";
   const char* topic = "test-multiple";
-  int async = 1, restart = 0, keep = 1;
+  int async = 1, restart = 0, keep = 1, test = 0;
   TAOS_SUB* tsub = NULL;
 
   for (int i = 1; i < argc; i++) {
@@ -68,6 +157,10 @@ int main(int argc, char *argv[]) {
       topic = "test-custom";
       continue;
     }
+    if (strcmp(argv[i], "-test") == 0) {
+      test = 1;
+      continue;
+    }
   }
 
   // init TAOS
@@ -79,6 +172,12 @@ int main(int argc, char *argv[]) {
     exit(1);
   }
 
+  if (test) {
+    run_test(taos);
+    taos_close(taos);
+    exit(0);
+  }
+
   if (async) {
     tsub = taos_subscribe(taos, restart, topic, sql, subscribe_callback, NULL, 1000);
   } else {
@@ -99,6 +198,7 @@ int main(int argc, char *argv[]) {
   }
 
   taos_unsubscribe(tsub, keep);
+  taos_close(taos);
 
   return 0;
 }

From 244cfe217c0bc0d4048c856b0ee0af6a104a1d9b Mon Sep 17 00:00:00 2001
From: localvar <localvar@hotmail.com>
Date: Fri, 10 Jan 2020 14:21:48 +0800
Subject: [PATCH 13/35] add more log

---
 src/client/src/tscSub.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/src/client/src/tscSub.c b/src/client/src/tscSub.c
index 225d3f0e6f..fc52f7ac2f 100644
--- a/src/client/src/tscSub.c
+++ b/src/client/src/tscSub.c
@@ -323,6 +323,7 @@ TAOS_SUB *taos_subscribe(TAOS *taos, int restart, const char* topic, const char
 
   pSub->interval = interval;
   if (fp != NULL) {
+    tscTrace("asynchronize subscription, create new timer", topic);
     pSub->fp = fp;
     pSub->param = param;
     taosTmrReset(tscProcessSubscriptionTimer, interval, pSub, tscTmr, &pSub->pTimer);
@@ -343,17 +344,20 @@ TAOS_RES *taos_consume(TAOS_SUB *tsub) {
   if (pSub->pTimer == NULL) {
     int duration = (int)(taosGetTimestampMs() - pSub->lastConsumeTime);
     if (duration < pSub->interval) {
+      tscTrace("subscription consume too frequently, blocking...");
       taosMsleep(pSub->interval - (int32_t)duration);
     }
   }
 
   if (taosGetTimestampMs() - pSub->lastSyncTime > 10 * 60 * 1000) {
+    tscTrace("begin meter synchronization");
     char* sqlstr = pSql->sqlstr;
     pSql->sqlstr = NULL;
     taos_free_result_imp(pSql, 0);
     pSql->sqlstr = sqlstr;
     taosClearDataCache(tscCacheHandle);
     if (!tscUpdateSubscription(pSub->taos, pSub)) return NULL;
+    tscTrace("meter synchronization completed");
   } else {
     uint16_t type = pSql->cmd.type;
     taos_free_result_imp(pSql, 1);
@@ -365,9 +369,9 @@ TAOS_RES *taos_consume(TAOS_SUB *tsub) {
     pSql->cmd.type = type;
   }
 
-
   tscDoQuery(pSql);
   if (pRes->code != TSDB_CODE_SUCCESS) {
+    tscError("failed to query data, error code=%d", pRes->code);
     tscRemoveFromSqlList(pSql);
     return NULL;
   }

From 5d398eb8a43ac6ec805938e7756a2d0cc76d804f Mon Sep 17 00:00:00 2001
From: localvar <localvar@hotmail.com>
Date: Sat, 11 Jan 2020 13:50:12 +0800
Subject: [PATCH 14/35] check memory allocation failure

---
 src/client/src/tscSub.c | 28 +++++++++++++++++-----------
 1 file changed, 17 insertions(+), 11 deletions(-)

diff --git a/src/client/src/tscSub.c b/src/client/src/tscSub.c
index fc52f7ac2f..685a26a46e 100644
--- a/src/client/src/tscSub.c
+++ b/src/client/src/tscSub.c
@@ -164,9 +164,6 @@ int tscUpdateSubscription(STscObj* pObj, SSub* pSub) {
     return 0;
   }
 
-  int numOfMeters = 0;
-  SSubscriptionProgress* progress = NULL;
-
   SSqlCmd* pCmd = &pSub->pSql->cmd;
   if (pCmd->command != TSDB_SQL_SELECT) {
     tscError("only 'select' statement is allowed in subscription: %s", pSub->topic);
@@ -174,19 +171,28 @@ int tscUpdateSubscription(STscObj* pObj, SSub* pSub) {
   }
 
   SMeterMetaInfo *pMeterMetaInfo = tscGetMeterMetaInfo(pCmd, 0);
-  if (UTIL_METER_IS_NOMRAL_METER(pMeterMetaInfo)) {
-    numOfMeters = 1;
-    progress = calloc(1, sizeof(SSubscriptionProgress));
-    int64_t uid = pMeterMetaInfo->pMeterMeta->uid;
-    progress[0].uid = uid;
-    progress[0].key = tscGetSubscriptionProgress(pSub, uid);
-  } else {
+  int numOfMeters = 0;
+  if (!UTIL_METER_IS_NOMRAL_METER(pMeterMetaInfo)) {
     SMetricMeta* pMetricMeta = pMeterMetaInfo->pMetricMeta;
     for (int32_t i = 0; i < pMetricMeta->numOfVnodes; i++) {
       SVnodeSidList *pVnodeSidList = tscGetVnodeSidList(pMetricMeta, pMeterMetaInfo->vnodeIndex);
       numOfMeters += pVnodeSidList->numOfSids;
     }
-    progress = calloc(numOfMeters, sizeof(SSubscriptionProgress));
+  }
+
+  SSubscriptionProgress* progress = (SSubscriptionProgress*)calloc(numOfMeters, sizeof(SSubscriptionProgress));
+  if (progress == NULL) {
+    tscError("failed to allocate memory for progress: %s", pSub->topic);
+    return 0;
+  }
+
+  if (UTIL_METER_IS_NOMRAL_METER(pMeterMetaInfo)) {
+    numOfMeters = 1;
+    int64_t uid = pMeterMetaInfo->pMeterMeta->uid;
+    progress[0].uid = uid;
+    progress[0].key = tscGetSubscriptionProgress(pSub, uid);
+  } else {
+    SMetricMeta* pMetricMeta = pMeterMetaInfo->pMetricMeta;
     numOfMeters = 0;
     for (int32_t i = 0; i < pMetricMeta->numOfVnodes; i++) {
       SVnodeSidList *pVnodeSidList = tscGetVnodeSidList(pMetricMeta, pMeterMetaInfo->vnodeIndex);

From bae48b73c6733b65fd9abd9fa5154d12c4e2ce1e Mon Sep 17 00:00:00 2001
From: localvar <localvar@hotmail.com>
Date: Mon, 13 Jan 2020 16:50:17 +0800
Subject: [PATCH 15/35] fix two bugs:

1. taos_consume block for evev
2. taos_fetch_block returns 0 in subscription
---
 src/client/src/tscSql.c      |  2 +-
 src/client/src/tscSub.c      |  4 ++--
 tests/examples/c/subscribe.c | 15 ++++++++++++++-
 3 files changed, 17 insertions(+), 4 deletions(-)

diff --git a/src/client/src/tscSql.c b/src/client/src/tscSql.c
index ad4a29f20e..43c1fc9ce9 100644
--- a/src/client/src/tscSql.c
+++ b/src/client/src/tscSql.c
@@ -344,7 +344,7 @@ int taos_fetch_block_impl(TAOS_RES *res, TAOS_ROW *rows) {
   SSqlRes *pRes = &pSql->res;
   STscObj *pObj = pSql->pTscObj;
 
-  if (pRes->qhandle == 0 || pObj->pSql != pSql) {
+  if (pRes->qhandle == 0) {
     *rows = NULL;
     return 0;
   }
diff --git a/src/client/src/tscSub.c b/src/client/src/tscSub.c
index 685a26a46e..17a5031fa6 100644
--- a/src/client/src/tscSub.c
+++ b/src/client/src/tscSub.c
@@ -348,8 +348,8 @@ TAOS_RES *taos_consume(TAOS_SUB *tsub) {
   SSqlRes *pRes = &pSql->res;
 
   if (pSub->pTimer == NULL) {
-    int duration = (int)(taosGetTimestampMs() - pSub->lastConsumeTime);
-    if (duration < pSub->interval) {
+    int64_t duration = taosGetTimestampMs() - pSub->lastConsumeTime;
+    if (duration < (int64_t)(pSub->interval)) {
       tscTrace("subscription consume too frequently, blocking...");
       taosMsleep(pSub->interval - (int32_t)duration);
     }
diff --git a/tests/examples/c/subscribe.c b/tests/examples/c/subscribe.c
index 078929a9b8..04d000ba37 100644
--- a/tests/examples/c/subscribe.c
+++ b/tests/examples/c/subscribe.c
@@ -8,15 +8,28 @@
 #include <unistd.h>
 
 void print_result(TAOS_RES* res) {
-  TAOS_ROW    row;
+  TAOS_ROW    row = NULL;
   int         num_fields = taos_num_fields(res);
   TAOS_FIELD* fields = taos_fetch_fields(res);
 
+#if 0
+
+  int nRows = taos_fetch_block(res, &row);
+  for (int i = 0; i < nRows; i++) {
+    char temp[256];
+    taos_print_row(temp, row + i, fields, num_fields);
+    puts(temp);
+  }
+
+#else
+
   while ((row = taos_fetch_row(res))) {
     char temp[256];
     taos_print_row(temp, row, fields, num_fields);
     puts(temp);
   }
+
+#endif
 }
 
 void subscribe_callback(TAOS_SUB* tsub, TAOS_RES *res, void* param, int code) {

From 781c0ff6bc7f59ca612f32c3b7bedac909d1b1da Mon Sep 17 00:00:00 2001
From: localvar <localvar@hotmail.com>
Date: Mon, 13 Jan 2020 16:57:56 +0800
Subject: [PATCH 16/35] TBASE-1470: python3 & linux

---
 .../python/linux/python3/taos/cinterface.py   | 37 +++++++++++++++++++
 .../python/linux/python3/taos/connection.py   | 10 ++++-
 .../python/linux/python3/taos/subscription.py | 36 ++++++++++++++++++
 3 files changed, 82 insertions(+), 1 deletion(-)
 create mode 100644 src/connector/python/linux/python3/taos/subscription.py

diff --git a/src/connector/python/linux/python3/taos/cinterface.py b/src/connector/python/linux/python3/taos/cinterface.py
index 259c8bbd06..7fcedc9fe9 100644
--- a/src/connector/python/linux/python3/taos/cinterface.py
+++ b/src/connector/python/linux/python3/taos/cinterface.py
@@ -144,6 +144,8 @@ class CTaosInterface(object):
     libtaos.taos_use_result.restype = ctypes.c_void_p
     libtaos.taos_fetch_row.restype = ctypes.POINTER(ctypes.c_void_p)
     libtaos.taos_errstr.restype = ctypes.c_char_p
+    libtaos.taos_subscribe.restype = ctypes.c_void_p
+    libtaos.taos_consume.restype = ctypes.c_void_p
 
     def __init__(self, config=None):
         '''
@@ -252,6 +254,41 @@ class CTaosInterface(object):
         """
         return CTaosInterface.libtaos.taos_affected_rows(connection)
 
+    @staticmethod
+    def subscribe(connection, restart, topic, sql, interval):
+        """Create a subscription
+         @restart boolean, 
+         @sql string, sql statement for data query, must be a 'select' statement.
+         @topic string, name of this subscription
+        """
+        return ctypes.c_void_p(CTaosInterface.libtaos.taos_subscribe(
+            connection,
+            1 if restart else 0,
+            ctypes.c_char_p(topic.encode('utf-8')),
+            ctypes.c_char_p(sql.encode('utf-8')),
+            None,
+            None,
+            interval))
+
+    @staticmethod
+    def consume(sub):
+        """Consume data of a subscription
+        """
+        result = ctypes.c_void_p(CTaosInterface.libtaos.taos_consume(sub))
+        fields = []
+        pfields = CTaosInterface.fetchFields(result)
+        for i in range(CTaosInterface.libtaos.taos_num_fields(result)):
+            fields.append({'name': pfields[i].name.decode('utf-8'),
+                           'bytes': pfields[i].bytes,
+                           'type': ord(pfields[i].type)})
+        return result, fields
+
+    @staticmethod
+    def unsubscribe(sub, keepProgress):
+        """Cancel a subscription
+        """
+        CTaosInterface.libtaos.taos_unsubscribe(sub, 1 if keepProgress else 0)
+
     @staticmethod
     def useResult(connection):
         '''Use result after calling self.query
diff --git a/src/connector/python/linux/python3/taos/connection.py b/src/connector/python/linux/python3/taos/connection.py
index ba24209552..04fbbdec04 100644
--- a/src/connector/python/linux/python3/taos/connection.py
+++ b/src/connector/python/linux/python3/taos/connection.py
@@ -1,5 +1,5 @@
-# from .cursor import TDengineCursor
 from .cursor import TDengineCursor
+from .subscription import TDengineSubscription
 from .cinterface import CTaosInterface
 
 class TDengineConnection(object):
@@ -50,6 +50,14 @@ class TDengineConnection(object):
         """
         return CTaosInterface.close(self._conn)
 
+    def subscribe(self, restart, topic, sql, interval):
+        """Create a subscription.
+        """
+        if self._conn is None:
+            return None
+        sub = CTaosInterface.subscribe(self._conn, restart, topic, sql, interval)
+        return TDengineSubscription(sub)
+
     def cursor(self):
         """Return a new Cursor object using the connection.
         """
diff --git a/src/connector/python/linux/python3/taos/subscription.py b/src/connector/python/linux/python3/taos/subscription.py
new file mode 100644
index 0000000000..c33243bb67
--- /dev/null
+++ b/src/connector/python/linux/python3/taos/subscription.py
@@ -0,0 +1,36 @@
+from .cinterface import CTaosInterface
+from .error import *
+
+class TDengineSubscription(object):
+    """TDengine subscription object
+    """
+    def __init__(self, sub):
+        self._sub = sub
+    
+
+    def consume(self):
+        """Consume rows of a subscription
+        """
+        if self._sub is None:
+            raise OperationalError("Invalid use of consume")
+        
+        result, fields = CTaosInterface.consume(self._sub)
+        buffer = [[] for i in range(len(fields))]
+        print(buffer)
+        while True:
+            block, num_of_fields = CTaosInterface.fetchBlock(result, fields)
+            if num_of_fields == 0: break
+            for i in range(len(fields)):
+                buffer[i].extend(block[i])
+
+        return list(map(tuple, zip(*buffer)))
+
+
+    def close(self, keepProgress = True):
+        """Close the Subscription.
+        """
+        if self._sub is None:
+            return False
+        
+        CTaosInterface.unsubscribe(self._sub, keepProgress)
+        return True

From f12c270e69955146460f57a226b2588041faecbf Mon Sep 17 00:00:00 2001
From: localvar <localvar@hotmail.com>
Date: Tue, 14 Jan 2020 10:16:11 +0800
Subject: [PATCH 17/35] tbase-1470: python2, linux

---
 .../python/linux/python2/taos/cinterface.py   | 65 +++++++++++++++++--
 .../python/linux/python2/taos/connection.py   | 10 ++-
 .../python/linux/python2/taos/subscription.py | 52 +++++++++++++++
 .../python/linux/python3/taos/subscription.py | 20 +++++-
 4 files changed, 138 insertions(+), 9 deletions(-)
 create mode 100644 src/connector/python/linux/python2/taos/subscription.py

diff --git a/src/connector/python/linux/python2/taos/cinterface.py b/src/connector/python/linux/python2/taos/cinterface.py
index 86a3489d07..505619436c 100644
--- a/src/connector/python/linux/python2/taos/cinterface.py
+++ b/src/connector/python/linux/python2/taos/cinterface.py
@@ -13,14 +13,14 @@ def _convert_microsecond_to_datetime(micro):
 def _crow_timestamp_to_python(data, num_of_rows, nbytes=None, micro=False):
     """Function to convert C bool row to python row
     """
-    _timstamp_converter = _convert_millisecond_to_datetime
+    _timestamp_converter = _convert_millisecond_to_datetime
     if micro:
-        _timstamp_converter = _convert_microsecond_to_datetime
+        _timestamp_converter = _convert_microsecond_to_datetime
 
     if num_of_rows > 0:
-        return list(map(_timstamp_converter, ctypes.cast(data,  ctypes.POINTER(ctypes.c_long))[:abs(num_of_rows)][::-1]))
+        return list(map(_timestamp_converter, ctypes.cast(data,  ctypes.POINTER(ctypes.c_long))[:abs(num_of_rows)][::-1]))
     else:
-        return list(map(_timstamp_converter, ctypes.cast(data,  ctypes.POINTER(ctypes.c_long))[:abs(num_of_rows)]))
+        return list(map(_timestamp_converter, ctypes.cast(data,  ctypes.POINTER(ctypes.c_long))[:abs(num_of_rows)]))
 
 def _crow_bool_to_python(data, num_of_rows, nbytes=None, micro=False):
     """Function to convert C bool row to python row
@@ -144,6 +144,8 @@ class CTaosInterface(object):
     libtaos.taos_use_result.restype = ctypes.c_void_p
     libtaos.taos_fetch_row.restype = ctypes.POINTER(ctypes.c_void_p)
     libtaos.taos_errstr.restype = ctypes.c_char_p
+    libtaos.taos_subscribe.restype = ctypes.c_void_p
+    libtaos.taos_consume.restype = ctypes.c_void_p
 
     def __init__(self, config=None):
         '''
@@ -252,6 +254,41 @@ class CTaosInterface(object):
         """
         return CTaosInterface.libtaos.taos_affected_rows(connection)
 
+    @staticmethod
+    def subscribe(connection, restart, topic, sql, interval):
+        """Create a subscription
+         @restart boolean, 
+         @sql string, sql statement for data query, must be a 'select' statement.
+         @topic string, name of this subscription
+        """
+        return ctypes.c_void_p(CTaosInterface.libtaos.taos_subscribe(
+            connection,
+            1 if restart else 0,
+            ctypes.c_char_p(topic.encode('utf-8')),
+            ctypes.c_char_p(sql.encode('utf-8')),
+            None,
+            None,
+            interval))
+
+    @staticmethod
+    def consume(sub):
+        """Consume data of a subscription
+        """
+        result = ctypes.c_void_p(CTaosInterface.libtaos.taos_consume(sub))
+        fields = []
+        pfields = CTaosInterface.fetchFields(result)
+        for i in range(CTaosInterface.libtaos.taos_num_fields(result)):
+            fields.append({'name': pfields[i].name.decode('utf-8'),
+                           'bytes': pfields[i].bytes,
+                           'type': ord(pfields[i].type)})
+        return result, fields
+
+    @staticmethod
+    def unsubscribe(sub, keepProgress):
+        """Cancel a subscription
+        """
+        CTaosInterface.libtaos.taos_unsubscribe(sub, 1 if keepProgress else 0)
+
     @staticmethod
     def useResult(connection):
         '''Use result after calling self.query
@@ -275,8 +312,8 @@ class CTaosInterface(object):
         if num_of_rows == 0:
             return None, 0
 
-        blocks = [None] * len(fields)
         isMicro = (CTaosInterface.libtaos.taos_result_precision(result) == FieldType.C_TIMESTAMP_MICRO)
+        blocks = [None] * len(fields)
         for i in range(len(fields)):
             data = ctypes.cast(pblock, ctypes.POINTER(ctypes.c_void_p))[i]
 
@@ -351,4 +388,20 @@ class CTaosInterface(object):
     def errStr(connection):
         """Return the error styring
         """
-        return CTaosInterface.libtaos.taos_errstr(connection)
\ No newline at end of file
+        return CTaosInterface.libtaos.taos_errstr(connection)
+
+
+if __name__ == '__main__':
+    cinter = CTaosInterface()
+    conn = cinter.connect()
+
+    print('Query return value: {}'.format(cinter.query(conn, 'show databases')))
+    print('Affected rows: {}'.format(cinter.affectedRows(conn)))
+
+    result, des = CTaosInterface.useResult(conn)
+
+    data, num_of_rows = CTaosInterface.fetchBlock(result, des)
+
+    print(data)
+
+    cinter.close(conn)
\ No newline at end of file
diff --git a/src/connector/python/linux/python2/taos/connection.py b/src/connector/python/linux/python2/taos/connection.py
index ba24209552..04fbbdec04 100644
--- a/src/connector/python/linux/python2/taos/connection.py
+++ b/src/connector/python/linux/python2/taos/connection.py
@@ -1,5 +1,5 @@
-# from .cursor import TDengineCursor
 from .cursor import TDengineCursor
+from .subscription import TDengineSubscription
 from .cinterface import CTaosInterface
 
 class TDengineConnection(object):
@@ -50,6 +50,14 @@ class TDengineConnection(object):
         """
         return CTaosInterface.close(self._conn)
 
+    def subscribe(self, restart, topic, sql, interval):
+        """Create a subscription.
+        """
+        if self._conn is None:
+            return None
+        sub = CTaosInterface.subscribe(self._conn, restart, topic, sql, interval)
+        return TDengineSubscription(sub)
+
     def cursor(self):
         """Return a new Cursor object using the connection.
         """
diff --git a/src/connector/python/linux/python2/taos/subscription.py b/src/connector/python/linux/python2/taos/subscription.py
new file mode 100644
index 0000000000..cbba3d59ca
--- /dev/null
+++ b/src/connector/python/linux/python2/taos/subscription.py
@@ -0,0 +1,52 @@
+from .cinterface import CTaosInterface
+from .error import *
+
+class TDengineSubscription(object):
+    """TDengine subscription object
+    """
+    def __init__(self, sub):
+        self._sub = sub
+    
+
+    def consume(self):
+        """Consume rows of a subscription
+        """
+        if self._sub is None:
+            raise OperationalError("Invalid use of consume")
+        
+        result, fields = CTaosInterface.consume(self._sub)
+        buffer = [[] for i in range(len(fields))]
+        print(buffer)
+        while True:
+            block, num_of_fields = CTaosInterface.fetchBlock(result, fields)
+            if num_of_fields == 0: break
+            for i in range(len(fields)):
+                buffer[i].extend(block[i])
+
+        return list(map(tuple, zip(*buffer)))
+
+
+    def close(self, keepProgress = True):
+        """Close the Subscription.
+        """
+        if self._sub is None:
+            return False
+        
+        CTaosInterface.unsubscribe(self._sub, keepProgress)
+        return True
+
+
+if __name__ == '__main__':
+    from .connection import TDengineConnection
+    conn = TDengineConnection(host="127.0.0.1", user="root", password="taosdata", database="test")
+
+    # Generate a cursor object to run SQL commands
+    sub = conn.subscribe(True, "test", "select * from meters;", 1000)
+
+    for i in range(0,10):
+        data = sub.consume()
+        for d in data:
+            print(d)
+
+    sub.close()
+    conn.close()
\ No newline at end of file
diff --git a/src/connector/python/linux/python3/taos/subscription.py b/src/connector/python/linux/python3/taos/subscription.py
index c33243bb67..3af989a138 100644
--- a/src/connector/python/linux/python3/taos/subscription.py
+++ b/src/connector/python/linux/python3/taos/subscription.py
@@ -6,7 +6,7 @@ class TDengineSubscription(object):
     """
     def __init__(self, sub):
         self._sub = sub
-    
+
 
     def consume(self):
         """Consume rows of a subscription
@@ -31,6 +31,22 @@ class TDengineSubscription(object):
         """
         if self._sub is None:
             return False
-        
+
         CTaosInterface.unsubscribe(self._sub, keepProgress)
         return True
+
+
+if __name__ == '__main__':
+    from .connection import TDengineConnection
+    conn = TDengineConnection(host="127.0.0.1", user="root", password="taosdata", database="test")
+
+    # Generate a cursor object to run SQL commands
+    sub = conn.subscribe(True, "test", "select * from meters;", 1000)
+
+    for i in range(0,10):
+        data = sub.consume()
+        for d in data:
+            print(d)
+
+    sub.close()
+    conn.close()
\ No newline at end of file

From a7eaa8ad7e617e6fa2999b5e80a0a178c0cd077a Mon Sep 17 00:00:00 2001
From: localvar <localvar@hotmail.com>
Date: Tue, 14 Jan 2020 10:50:30 +0800
Subject: [PATCH 18/35] tbase-1470: python2&3, windows

---
 .../python/windows/python2/taos/cinterface.py |  65 +-
 .../python/windows/python2/taos/connection.py |  13 +-
 .../windows/python2/taos/subscription.py      |  52 ++
 .../python/windows/python3/taos/cinterface.py | 775 +++++++++---------
 .../python/windows/python3/taos/connection.py | 168 ++--
 .../windows/python3/taos/subscription.py      |  52 ++
 6 files changed, 668 insertions(+), 457 deletions(-)
 create mode 100644 src/connector/python/windows/python2/taos/subscription.py
 create mode 100644 src/connector/python/windows/python3/taos/subscription.py

diff --git a/src/connector/python/windows/python2/taos/cinterface.py b/src/connector/python/windows/python2/taos/cinterface.py
index 8e3b701929..f8cdfcc51e 100644
--- a/src/connector/python/windows/python2/taos/cinterface.py
+++ b/src/connector/python/windows/python2/taos/cinterface.py
@@ -13,14 +13,14 @@ def _convert_microsecond_to_datetime(micro):
 def _crow_timestamp_to_python(data, num_of_rows, nbytes=None, micro=False):
     """Function to convert C bool row to python row
     """
-    _timstamp_converter = _convert_millisecond_to_datetime
+    _timestamp_converter = _convert_millisecond_to_datetime
     if micro:
-        _timstamp_converter = _convert_microsecond_to_datetime
+        _timestamp_converter = _convert_microsecond_to_datetime
 
     if num_of_rows > 0:
-        return list(map(_timstamp_converter, ctypes.cast(data,  ctypes.POINTER(ctypes.c_longlong))[:abs(num_of_rows)][::-1]))
+        return list(map(_timestamp_converter, ctypes.cast(data,  ctypes.POINTER(ctypes.c_longlong))[:abs(num_of_rows)][::-1]))
     else:
-        return list(map(_timstamp_converter, ctypes.cast(data,  ctypes.POINTER(ctypes.c_longlong))[:abs(num_of_rows)]))
+        return list(map(_timestamp_converter, ctypes.cast(data,  ctypes.POINTER(ctypes.c_longlong))[:abs(num_of_rows)]))
 
 def _crow_bool_to_python(data, num_of_rows, nbytes=None, micro=False):
     """Function to convert C bool row to python row
@@ -144,6 +144,8 @@ class CTaosInterface(object):
     libtaos.taos_use_result.restype = ctypes.c_void_p
     libtaos.taos_fetch_row.restype = ctypes.POINTER(ctypes.c_void_p)
     libtaos.taos_errstr.restype = ctypes.c_char_p
+    libtaos.taos_subscribe.restype = ctypes.c_void_p
+    libtaos.taos_consume.restype = ctypes.c_void_p
 
     def __init__(self, config=None):
         '''
@@ -252,6 +254,41 @@ class CTaosInterface(object):
         """
         return CTaosInterface.libtaos.taos_affected_rows(connection)
 
+    @staticmethod
+    def subscribe(connection, restart, topic, sql, interval):
+        """Create a subscription
+         @restart boolean, 
+         @sql string, sql statement for data query, must be a 'select' statement.
+         @topic string, name of this subscription
+        """
+        return ctypes.c_void_p(CTaosInterface.libtaos.taos_subscribe(
+            connection,
+            1 if restart else 0,
+            ctypes.c_char_p(topic.encode('utf-8')),
+            ctypes.c_char_p(sql.encode('utf-8')),
+            None,
+            None,
+            interval))
+
+    @staticmethod
+    def consume(sub):
+        """Consume data of a subscription
+        """
+        result = ctypes.c_void_p(CTaosInterface.libtaos.taos_consume(sub))
+        fields = []
+        pfields = CTaosInterface.fetchFields(result)
+        for i in range(CTaosInterface.libtaos.taos_num_fields(result)):
+            fields.append({'name': pfields[i].name.decode('utf-8'),
+                           'bytes': pfields[i].bytes,
+                           'type': ord(pfields[i].type)})
+        return result, fields
+
+    @staticmethod
+    def unsubscribe(sub, keepProgress):
+        """Cancel a subscription
+        """
+        CTaosInterface.libtaos.taos_unsubscribe(sub, 1 if keepProgress else 0)
+
     @staticmethod
     def useResult(connection):
         '''Use result after calling self.query
@@ -275,8 +312,8 @@ class CTaosInterface(object):
         if num_of_rows == 0:
             return None, 0
 
-        blocks = [None] * len(fields)
         isMicro = (CTaosInterface.libtaos.taos_result_precision(result) == FieldType.C_TIMESTAMP_MICRO)
+        blocks = [None] * len(fields)
         for i in range(len(fields)):
             data = ctypes.cast(pblock, ctypes.POINTER(ctypes.c_void_p))[i]
 
@@ -351,4 +388,20 @@ class CTaosInterface(object):
     def errStr(connection):
         """Return the error styring
         """
-        return CTaosInterface.libtaos.taos_errstr(connection)
\ No newline at end of file
+        return CTaosInterface.libtaos.taos_errstr(connection)
+
+
+if __name__ == '__main__':
+    cinter = CTaosInterface()
+    conn = cinter.connect()
+
+    print('Query return value: {}'.format(cinter.query(conn, 'show databases')))
+    print('Affected rows: {}'.format(cinter.affectedRows(conn)))
+
+    result, des = CTaosInterface.useResult(conn)
+
+    data, num_of_rows = CTaosInterface.fetchBlock(result, des)
+
+    print(data)
+
+    cinter.close(conn)
\ No newline at end of file
diff --git a/src/connector/python/windows/python2/taos/connection.py b/src/connector/python/windows/python2/taos/connection.py
index ba24209552..e2783975d9 100644
--- a/src/connector/python/windows/python2/taos/connection.py
+++ b/src/connector/python/windows/python2/taos/connection.py
@@ -1,5 +1,5 @@
-# from .cursor import TDengineCursor
 from .cursor import TDengineCursor
+from .subscription import TDengineSubscription
 from .cinterface import CTaosInterface
 
 class TDengineConnection(object):
@@ -15,7 +15,8 @@ class TDengineConnection(object):
         self._config = None
         self._chandle = None
 
-        self.config(**kwargs)
+        if len(kwargs) > 0:
+            self.config(**kwargs)
 
     def config(self, **kwargs):
         # host
@@ -50,6 +51,14 @@ class TDengineConnection(object):
         """
         return CTaosInterface.close(self._conn)
 
+    def subscribe(self, restart, topic, sql, interval):
+        """Create a subscription.
+        """
+        if self._conn is None:
+            return None
+        sub = CTaosInterface.subscribe(self._conn, restart, topic, sql, interval)
+        return TDengineSubscription(sub)
+
     def cursor(self):
         """Return a new Cursor object using the connection.
         """
diff --git a/src/connector/python/windows/python2/taos/subscription.py b/src/connector/python/windows/python2/taos/subscription.py
new file mode 100644
index 0000000000..3af989a138
--- /dev/null
+++ b/src/connector/python/windows/python2/taos/subscription.py
@@ -0,0 +1,52 @@
+from .cinterface import CTaosInterface
+from .error import *
+
+class TDengineSubscription(object):
+    """TDengine subscription object
+    """
+    def __init__(self, sub):
+        self._sub = sub
+
+
+    def consume(self):
+        """Consume rows of a subscription
+        """
+        if self._sub is None:
+            raise OperationalError("Invalid use of consume")
+        
+        result, fields = CTaosInterface.consume(self._sub)
+        buffer = [[] for i in range(len(fields))]
+        print(buffer)
+        while True:
+            block, num_of_fields = CTaosInterface.fetchBlock(result, fields)
+            if num_of_fields == 0: break
+            for i in range(len(fields)):
+                buffer[i].extend(block[i])
+
+        return list(map(tuple, zip(*buffer)))
+
+
+    def close(self, keepProgress = True):
+        """Close the Subscription.
+        """
+        if self._sub is None:
+            return False
+
+        CTaosInterface.unsubscribe(self._sub, keepProgress)
+        return True
+
+
+if __name__ == '__main__':
+    from .connection import TDengineConnection
+    conn = TDengineConnection(host="127.0.0.1", user="root", password="taosdata", database="test")
+
+    # Generate a cursor object to run SQL commands
+    sub = conn.subscribe(True, "test", "select * from meters;", 1000)
+
+    for i in range(0,10):
+        data = sub.consume()
+        for d in data:
+            print(d)
+
+    sub.close()
+    conn.close()
\ No newline at end of file
diff --git a/src/connector/python/windows/python3/taos/cinterface.py b/src/connector/python/windows/python3/taos/cinterface.py
index 2cddf5fccf..b4b44e199c 100644
--- a/src/connector/python/windows/python3/taos/cinterface.py
+++ b/src/connector/python/windows/python3/taos/cinterface.py
@@ -1,370 +1,407 @@
-import ctypes
-from .constants import FieldType
-from .error import *
-import math
-import datetime
-
-def _convert_millisecond_to_datetime(milli):
-    return datetime.datetime.fromtimestamp(milli/1000.0)
-
-def _convert_microsecond_to_datetime(micro):
-    return datetime.datetime.fromtimestamp(micro/1000000.0)
-
-def _crow_timestamp_to_python(data, num_of_rows, nbytes=None, micro=False):
-    """Function to convert C bool row to python row
-    """
-    _timestamp_converter = _convert_millisecond_to_datetime
-    if micro:
-        _timestamp_converter = _convert_microsecond_to_datetime
-
-    if num_of_rows > 0:
-        return list(map(_timestamp_converter, ctypes.cast(data,  ctypes.POINTER(ctypes.c_longlong))[:abs(num_of_rows)][::-1]))
-    else:
-        return list(map(_timestamp_converter, ctypes.cast(data,  ctypes.POINTER(ctypes.c_longlong))[:abs(num_of_rows)]))
-
-def _crow_bool_to_python(data, num_of_rows, nbytes=None, micro=False):
-    """Function to convert C bool row to python row
-    """
-    if num_of_rows > 0:
-        return [ None if ele == FieldType.C_BOOL_NULL else bool(ele) for ele in ctypes.cast(data,  ctypes.POINTER(ctypes.c_byte))[:abs(num_of_rows)][::-1] ]
-    else:
-        return [ None if ele == FieldType.C_BOOL_NULL else bool(ele) for ele in ctypes.cast(data,  ctypes.POINTER(ctypes.c_bool))[:abs(num_of_rows)] ]
-
-def _crow_tinyint_to_python(data, num_of_rows, nbytes=None, micro=False):
-    """Function to convert C tinyint row to python row
-    """
-    if num_of_rows > 0:
-        return [ None if ele == FieldType.C_TINYINT_NULL else ele for ele in ctypes.cast(data,  ctypes.POINTER(ctypes.c_byte))[:abs(num_of_rows)][::-1] ]
-    else:
-        return [ None if ele == FieldType.C_TINYINT_NULL else ele for ele in ctypes.cast(data,  ctypes.POINTER(ctypes.c_byte))[:abs(num_of_rows)] ]
-    
-def _crow_smallint_to_python(data, num_of_rows, nbytes=None, micro=False):
-    """Function to convert C smallint row to python row
-    """
-    if num_of_rows > 0:
-        return [ None if ele == FieldType.C_SMALLINT_NULL else ele for ele in ctypes.cast(data,  ctypes.POINTER(ctypes.c_short))[:abs(num_of_rows)][::-1]]
-    else:
-        return [ None if ele == FieldType.C_SMALLINT_NULL else ele for ele in ctypes.cast(data,  ctypes.POINTER(ctypes.c_short))[:abs(num_of_rows)] ]
-
-def _crow_int_to_python(data, num_of_rows, nbytes=None, micro=False):
-    """Function to convert C int row to python row
-    """
-    if num_of_rows > 0:
-        return [ None if ele == FieldType.C_INT_NULL else ele for ele in ctypes.cast(data,  ctypes.POINTER(ctypes.c_int))[:abs(num_of_rows)][::-1] ]
-    else:
-        return [ None if ele == FieldType.C_INT_NULL else ele for ele in ctypes.cast(data,  ctypes.POINTER(ctypes.c_int))[:abs(num_of_rows)] ]
-
-def _crow_bigint_to_python(data, num_of_rows, nbytes=None, micro=False):
-    """Function to convert C bigint row to python row
-    """
-    if num_of_rows > 0:
-        return [ None if ele == FieldType.C_BIGINT_NULL else ele for ele in ctypes.cast(data,  ctypes.POINTER(ctypes.c_longlong))[:abs(num_of_rows)][::-1] ]
-    else:
-        return [ None if ele == FieldType.C_BIGINT_NULL else ele for ele in ctypes.cast(data,  ctypes.POINTER(ctypes.c_longlong))[:abs(num_of_rows)] ]
-
-def _crow_float_to_python(data, num_of_rows, nbytes=None, micro=False):
-    """Function to convert C float row to python row
-    """
-    if num_of_rows > 0:
-        return [ None if math.isnan(ele) else ele for ele in ctypes.cast(data,  ctypes.POINTER(ctypes.c_float))[:abs(num_of_rows)][::-1] ]
-    else:
-        return [ None if math.isnan(ele) else ele for ele in ctypes.cast(data,  ctypes.POINTER(ctypes.c_float))[:abs(num_of_rows)] ]
-
-def _crow_double_to_python(data, num_of_rows, nbytes=None, micro=False):
-    """Function to convert C double row to python row
-    """
-    if num_of_rows > 0:
-        return [ None if math.isnan(ele) else ele for ele in ctypes.cast(data,  ctypes.POINTER(ctypes.c_double))[:abs(num_of_rows)][::-1] ]
-    else:
-        return [ None if math.isnan(ele) else ele for ele in ctypes.cast(data,  ctypes.POINTER(ctypes.c_double))[:abs(num_of_rows)] ]
-
-def _crow_binary_to_python(data, num_of_rows, nbytes=None, micro=False):
-    """Function to convert C binary row to python row
-    """
-    if num_of_rows > 0:
-        return [ None if ele.value[0:1] == FieldType.C_BINARY_NULL else ele.value.decode('utf-8') for ele in (ctypes.cast(data,  ctypes.POINTER(ctypes.c_char * nbytes)))[:abs(num_of_rows)][::-1]]
-    else:
-        return [ None if ele.value[0:1] == FieldType.C_BINARY_NULL else ele.value.decode('utf-8') for ele in (ctypes.cast(data,  ctypes.POINTER(ctypes.c_char * nbytes)))[:abs(num_of_rows)]]
-
-def _crow_nchar_to_python(data, num_of_rows, nbytes=None, micro=False):
-    """Function to convert C nchar row to python row
-    """
-    assert(nbytes is not None)
-
-    res = []
-
-    for i in range(abs(num_of_rows)):
-        try:
-            if num_of_rows >= 0:
-                res.append( (ctypes.cast(data+nbytes*(abs(num_of_rows - i -1)),  ctypes.POINTER(ctypes.c_wchar * (nbytes//4))))[0].value )
-            else:
-                res.append( (ctypes.cast(data+nbytes*i,  ctypes.POINTER(ctypes.c_wchar * (nbytes//4))))[0].value )
-        except ValueError:
-            res.append(None)
-
-    return res
-    # if num_of_rows > 0:
-    #     for i in range(abs(num_of_rows)):
-    #         try:
-    #             res.append( (ctypes.cast(data+nbytes*i,  ctypes.POINTER(ctypes.c_wchar * (nbytes//4))))[0].value )
-    #         except ValueError:
-    #             res.append(None)
-    #     return res
-    #         # return [ele.value for ele in (ctypes.cast(data,  ctypes.POINTER(ctypes.c_wchar * (nbytes//4))))[:abs(num_of_rows)][::-1]]
-    # else:
-    #     return [ele.value for ele in (ctypes.cast(data,  ctypes.POINTER(ctypes.c_wchar * (nbytes//4))))[:abs(num_of_rows)]]
-
-_CONVERT_FUNC = {
-    FieldType.C_BOOL: _crow_bool_to_python,
-    FieldType.C_TINYINT : _crow_tinyint_to_python,
-    FieldType.C_SMALLINT : _crow_smallint_to_python,
-    FieldType.C_INT : _crow_int_to_python,
-    FieldType.C_BIGINT : _crow_bigint_to_python,
-    FieldType.C_FLOAT : _crow_float_to_python,
-    FieldType.C_DOUBLE : _crow_double_to_python,
-    FieldType.C_BINARY: _crow_binary_to_python,
-    FieldType.C_TIMESTAMP : _crow_timestamp_to_python, 
-    FieldType.C_NCHAR : _crow_nchar_to_python
-}
-
-# Corresponding TAOS_FIELD structure in C
-class TaosField(ctypes.Structure):
-    _fields_ = [('name', ctypes.c_char * 64),
-                ('bytes', ctypes.c_short),
-                ('type', ctypes.c_char)]
-
-# C interface class
-class CTaosInterface(object):
-
-    libtaos = ctypes.windll.LoadLibrary('taos')
-
-    libtaos.taos_fetch_fields.restype = ctypes.POINTER(TaosField)
-    libtaos.taos_init.restype = None
-    libtaos.taos_connect.restype = ctypes.c_void_p
-    libtaos.taos_use_result.restype = ctypes.c_void_p
-    libtaos.taos_fetch_row.restype = ctypes.POINTER(ctypes.c_void_p)
-    libtaos.taos_errstr.restype = ctypes.c_char_p
-
-    def __init__(self, config=None):
-        '''
-        Function to initialize the class
-        @host     : str, hostname to connect
-        @user     : str, username to connect to server
-        @password : str, password to connect to server
-        @db       : str, default db to use when log in
-        @config   : str, config directory
-
-        @rtype    : None
-        '''
-        if config is None:
-            self._config = ctypes.c_char_p(None)
-        else:
-            try:
-                self._config = ctypes.c_char_p(config.encode('utf-8'))
-            except AttributeError:
-                raise AttributeError("config is expected as a str")
-
-        if config != None:
-            CTaosInterface.libtaos.taos_options(3, self._config)
-
-        CTaosInterface.libtaos.taos_init()
-
-    @property
-    def config(self):
-        """ Get current config
-        """
-        return self._config
-
-    def connect(self, host=None, user="root", password="taosdata", db=None, port=0):
-        '''
-        Function to connect to server
-
-        @rtype: c_void_p, TDengine handle
-        '''
-        # host
-        try:
-            _host = ctypes.c_char_p(host.encode(
-                "utf-8")) if host != None else ctypes.c_char_p(None)
-        except AttributeError:
-            raise AttributeError("host is expected as a str")
-
-        # user
-        try:
-            _user = ctypes.c_char_p(user.encode("utf-8"))
-        except AttributeError:
-            raise AttributeError("user is expected as a str")
-
-        # password
-        try:
-            _password = ctypes.c_char_p(password.encode("utf-8"))
-        except AttributeError:
-            raise AttributeError("password is expected as a str")
-
-        # db
-        try:
-            _db = ctypes.c_char_p(
-                db.encode("utf-8")) if db != None else ctypes.c_char_p(None)
-        except AttributeError:
-            raise AttributeError("db is expected as a str")
-
-        # port
-        try:
-            _port = ctypes.c_int(port)
-        except TypeError:
-            raise TypeError("port is expected as an int")
-
-        connection = ctypes.c_void_p(CTaosInterface.libtaos.taos_connect(
-            _host, _user, _password, _db, _port))
-
-        if connection.value == None:
-            print('connect to TDengine failed')
-            # sys.exit(1)
-        else:
-            print('connect to TDengine success')
-
-        return connection
-
-    @staticmethod
-    def close(connection):
-        '''Close the TDengine handle
-        '''
-        CTaosInterface.libtaos.taos_close(connection)
-        print('connection is closed')
-
-    @staticmethod
-    def query(connection, sql):
-        '''Run SQL
-
-        @sql: str, sql string to run
-
-        @rtype: 0 on success and -1 on failure
-        '''
-        try:
-            return CTaosInterface.libtaos.taos_query(connection, ctypes.c_char_p(sql.encode('utf-8')))
-        except AttributeError:
-           raise AttributeError("sql is expected as a string")
-        # finally:
-        #     CTaosInterface.libtaos.close(connection)
-
-    @staticmethod
-    def affectedRows(connection):
-        """The affected rows after runing query
-        """
-        return CTaosInterface.libtaos.taos_affected_rows(connection)
-
-    @staticmethod
-    def useResult(connection):
-        '''Use result after calling self.query
-        '''
-        result = ctypes.c_void_p(CTaosInterface.libtaos.taos_use_result(connection))
-        fields = []
-        pfields = CTaosInterface.fetchFields(result)
-        for i in range(CTaosInterface.fieldsCount(connection)):
-            fields.append({'name': pfields[i].name.decode('utf-8'),
-                           'bytes': pfields[i].bytes,
-                           'type': ord(pfields[i].type)})
-
-        return result, fields
-
-    @staticmethod
-    def fetchBlock(result, fields):
-        pblock = ctypes.c_void_p(0)
-        num_of_rows = CTaosInterface.libtaos.taos_fetch_block(
-            result, ctypes.byref(pblock))
-
-        if num_of_rows == 0:
-            return None, 0
-
-        isMicro = (CTaosInterface.libtaos.taos_result_precision(result) == FieldType.C_TIMESTAMP_MICRO)
-        blocks = [None] * len(fields)
-        for i in range(len(fields)):
-            data = ctypes.cast(pblock, ctypes.POINTER(ctypes.c_void_p))[i]
-
-            if fields[i]['type'] not in _CONVERT_FUNC:
-                raise DatabaseError("Invalid data type returned from database")
-            
-            blocks[i] = _CONVERT_FUNC[fields[i]['type']](data, num_of_rows, fields[i]['bytes'], isMicro)
-
-        return blocks, abs(num_of_rows)
-
-    @staticmethod
-    def freeResult(result):
-        CTaosInterface.libtaos.taos_free_result(result)
-        result.value = None
-
-    @staticmethod
-    def fieldsCount(connection):
-        return CTaosInterface.libtaos.taos_field_count(connection)
-
-    @staticmethod
-    def fetchFields(result):
-        return CTaosInterface.libtaos.taos_fetch_fields(result)
-
-    # @staticmethod
-    # def fetchRow(result, fields):
-    #     l = []
-    #     row = CTaosInterface.libtaos.taos_fetch_row(result)
-    #     if not row:
-    #         return None
-
-    #     for i in range(len(fields)):
-    #         l.append(CTaosInterface.getDataValue(
-    #             row[i], fields[i]['type'], fields[i]['bytes']))
-
-    #     return tuple(l)
-
-    # @staticmethod
-    # def getDataValue(data, dtype, byte):
-    #     '''
-    #     '''
-    #     if not data:
-    #         return None
-
-    #     if (dtype == CTaosInterface.TSDB_DATA_TYPE_BOOL):
-    #         return ctypes.cast(data,  ctypes.POINTER(ctypes.c_bool))[0]
-    #     elif (dtype == CTaosInterface.TSDB_DATA_TYPE_TINYINT):
-    #         return ctypes.cast(data,  ctypes.POINTER(ctypes.c_byte))[0]
-    #     elif (dtype == CTaosInterface.TSDB_DATA_TYPE_SMALLINT):
-    #         return ctypes.cast(data,  ctypes.POINTER(ctypes.c_short))[0]
-    #     elif (dtype == CTaosInterface.TSDB_DATA_TYPE_INT):
-    #         return ctypes.cast(data,  ctypes.POINTER(ctypes.c_int))[0]
-    #     elif (dtype == CTaosInterface.TSDB_DATA_TYPE_BIGINT):
-    #         return ctypes.cast(data,  ctypes.POINTER(ctypes.c_long))[0]
-    #     elif (dtype == CTaosInterface.TSDB_DATA_TYPE_FLOAT):
-    #         return ctypes.cast(data,  ctypes.POINTER(ctypes.c_float))[0]
-    #     elif (dtype == CTaosInterface.TSDB_DATA_TYPE_DOUBLE):
-    #         return ctypes.cast(data,  ctypes.POINTER(ctypes.c_double))[0]
-    #     elif (dtype == CTaosInterface.TSDB_DATA_TYPE_BINARY):
-    #         return (ctypes.cast(data,  ctypes.POINTER(ctypes.c_char))[0:byte]).rstrip('\x00')
-    #     elif (dtype == CTaosInterface.TSDB_DATA_TYPE_TIMESTAMP):
-    #         return ctypes.cast(data,  ctypes.POINTER(ctypes.c_long))[0]
-    #     elif (dtype == CTaosInterface.TSDB_DATA_TYPE_NCHAR):
-    #         return (ctypes.cast(data,  ctypes.c_char_p).value).rstrip('\x00')
-
-    @staticmethod
-    def errno(connection):
-        """Return the error number.
-        """
-        return CTaosInterface.libtaos.taos_errno(connection)
-
-    @staticmethod
-    def errStr(connection):
-        """Return the error styring
-        """
-        return CTaosInterface.libtaos.taos_errstr(connection).decode('utf-8')
-
-
-if __name__ == '__main__':
-    cinter = CTaosInterface()
-    conn = cinter.connect()
-
-    print('Query return value: {}'.format(cinter.query(conn, 'show databases')))
-    print('Affected rows: {}'.format(cinter.affectedRows(conn)))
-
-    result, des = CTaosInterface.useResult(conn)
-
-    data, num_of_rows = CTaosInterface.fetchBlock(result, des)
-
-    print(data)
-
+import ctypes
+from .constants import FieldType
+from .error import *
+import math
+import datetime
+
+def _convert_millisecond_to_datetime(milli):
+    return datetime.datetime.fromtimestamp(milli/1000.0)
+
+def _convert_microsecond_to_datetime(micro):
+    return datetime.datetime.fromtimestamp(micro/1000000.0)
+
+def _crow_timestamp_to_python(data, num_of_rows, nbytes=None, micro=False):
+    """Function to convert C bool row to python row
+    """
+    _timestamp_converter = _convert_millisecond_to_datetime
+    if micro:
+        _timestamp_converter = _convert_microsecond_to_datetime
+
+    if num_of_rows > 0:
+        return list(map(_timestamp_converter, ctypes.cast(data,  ctypes.POINTER(ctypes.c_longlong))[:abs(num_of_rows)][::-1]))
+    else:
+        return list(map(_timestamp_converter, ctypes.cast(data,  ctypes.POINTER(ctypes.c_longlong))[:abs(num_of_rows)]))
+
+def _crow_bool_to_python(data, num_of_rows, nbytes=None, micro=False):
+    """Function to convert C bool row to python row
+    """
+    if num_of_rows > 0:
+        return [ None if ele == FieldType.C_BOOL_NULL else bool(ele) for ele in ctypes.cast(data,  ctypes.POINTER(ctypes.c_byte))[:abs(num_of_rows)][::-1] ]
+    else:
+        return [ None if ele == FieldType.C_BOOL_NULL else bool(ele) for ele in ctypes.cast(data,  ctypes.POINTER(ctypes.c_bool))[:abs(num_of_rows)] ]
+
+def _crow_tinyint_to_python(data, num_of_rows, nbytes=None, micro=False):
+    """Function to convert C tinyint row to python row
+    """
+    if num_of_rows > 0:
+        return [ None if ele == FieldType.C_TINYINT_NULL else ele for ele in ctypes.cast(data,  ctypes.POINTER(ctypes.c_byte))[:abs(num_of_rows)][::-1] ]
+    else:
+        return [ None if ele == FieldType.C_TINYINT_NULL else ele for ele in ctypes.cast(data,  ctypes.POINTER(ctypes.c_byte))[:abs(num_of_rows)] ]
+    
+def _crow_smallint_to_python(data, num_of_rows, nbytes=None, micro=False):
+    """Function to convert C smallint row to python row
+    """
+    if num_of_rows > 0:
+        return [ None if ele == FieldType.C_SMALLINT_NULL else ele for ele in ctypes.cast(data,  ctypes.POINTER(ctypes.c_short))[:abs(num_of_rows)][::-1]]
+    else:
+        return [ None if ele == FieldType.C_SMALLINT_NULL else ele for ele in ctypes.cast(data,  ctypes.POINTER(ctypes.c_short))[:abs(num_of_rows)] ]
+
+def _crow_int_to_python(data, num_of_rows, nbytes=None, micro=False):
+    """Function to convert C int row to python row
+    """
+    if num_of_rows > 0:
+        return [ None if ele == FieldType.C_INT_NULL else ele for ele in ctypes.cast(data,  ctypes.POINTER(ctypes.c_int))[:abs(num_of_rows)][::-1] ]
+    else:
+        return [ None if ele == FieldType.C_INT_NULL else ele for ele in ctypes.cast(data,  ctypes.POINTER(ctypes.c_int))[:abs(num_of_rows)] ]
+
+def _crow_bigint_to_python(data, num_of_rows, nbytes=None, micro=False):
+    """Function to convert C bigint row to python row
+    """
+    if num_of_rows > 0:
+        return [ None if ele == FieldType.C_BIGINT_NULL else ele for ele in ctypes.cast(data,  ctypes.POINTER(ctypes.c_longlong))[:abs(num_of_rows)][::-1] ]
+    else:
+        return [ None if ele == FieldType.C_BIGINT_NULL else ele for ele in ctypes.cast(data,  ctypes.POINTER(ctypes.c_longlong))[:abs(num_of_rows)] ]
+
+def _crow_float_to_python(data, num_of_rows, nbytes=None, micro=False):
+    """Function to convert C float row to python row
+    """
+    if num_of_rows > 0:
+        return [ None if math.isnan(ele) else ele for ele in ctypes.cast(data,  ctypes.POINTER(ctypes.c_float))[:abs(num_of_rows)][::-1] ]
+    else:
+        return [ None if math.isnan(ele) else ele for ele in ctypes.cast(data,  ctypes.POINTER(ctypes.c_float))[:abs(num_of_rows)] ]
+
+def _crow_double_to_python(data, num_of_rows, nbytes=None, micro=False):
+    """Function to convert C double row to python row
+    """
+    if num_of_rows > 0:
+        return [ None if math.isnan(ele) else ele for ele in ctypes.cast(data,  ctypes.POINTER(ctypes.c_double))[:abs(num_of_rows)][::-1] ]
+    else:
+        return [ None if math.isnan(ele) else ele for ele in ctypes.cast(data,  ctypes.POINTER(ctypes.c_double))[:abs(num_of_rows)] ]
+
+def _crow_binary_to_python(data, num_of_rows, nbytes=None, micro=False):
+    """Function to convert C binary row to python row
+    """
+    if num_of_rows > 0:
+        return [ None if ele.value[0:1] == FieldType.C_BINARY_NULL else ele.value.decode('utf-8') for ele in (ctypes.cast(data,  ctypes.POINTER(ctypes.c_char * nbytes)))[:abs(num_of_rows)][::-1]]
+    else:
+        return [ None if ele.value[0:1] == FieldType.C_BINARY_NULL else ele.value.decode('utf-8') for ele in (ctypes.cast(data,  ctypes.POINTER(ctypes.c_char * nbytes)))[:abs(num_of_rows)]]
+
+def _crow_nchar_to_python(data, num_of_rows, nbytes=None, micro=False):
+    """Function to convert C nchar row to python row
+    """
+    assert(nbytes is not None)
+
+    res = []
+
+    for i in range(abs(num_of_rows)):
+        try:
+            if num_of_rows >= 0:
+                res.append( (ctypes.cast(data+nbytes*(abs(num_of_rows - i -1)),  ctypes.POINTER(ctypes.c_wchar * (nbytes//4))))[0].value )
+            else:
+                res.append( (ctypes.cast(data+nbytes*i,  ctypes.POINTER(ctypes.c_wchar * (nbytes//4))))[0].value )
+        except ValueError:
+            res.append(None)
+
+    return res
+    # if num_of_rows > 0:
+    #     for i in range(abs(num_of_rows)):
+    #         try:
+    #             res.append( (ctypes.cast(data+nbytes*i,  ctypes.POINTER(ctypes.c_wchar * (nbytes//4))))[0].value )
+    #         except ValueError:
+    #             res.append(None)
+    #     return res
+    #         # return [ele.value for ele in (ctypes.cast(data,  ctypes.POINTER(ctypes.c_wchar * (nbytes//4))))[:abs(num_of_rows)][::-1]]
+    # else:
+    #     return [ele.value for ele in (ctypes.cast(data,  ctypes.POINTER(ctypes.c_wchar * (nbytes//4))))[:abs(num_of_rows)]]
+
+_CONVERT_FUNC = {
+    FieldType.C_BOOL: _crow_bool_to_python,
+    FieldType.C_TINYINT : _crow_tinyint_to_python,
+    FieldType.C_SMALLINT : _crow_smallint_to_python,
+    FieldType.C_INT : _crow_int_to_python,
+    FieldType.C_BIGINT : _crow_bigint_to_python,
+    FieldType.C_FLOAT : _crow_float_to_python,
+    FieldType.C_DOUBLE : _crow_double_to_python,
+    FieldType.C_BINARY: _crow_binary_to_python,
+    FieldType.C_TIMESTAMP : _crow_timestamp_to_python, 
+    FieldType.C_NCHAR : _crow_nchar_to_python
+}
+
+# Corresponding TAOS_FIELD structure in C
+class TaosField(ctypes.Structure):
+    _fields_ = [('name', ctypes.c_char * 64),
+                ('bytes', ctypes.c_short),
+                ('type', ctypes.c_char)]
+
+# C interface class
+class CTaosInterface(object):
+
+    libtaos = ctypes.windll.LoadLibrary('taos')
+
+    libtaos.taos_fetch_fields.restype = ctypes.POINTER(TaosField)
+    libtaos.taos_init.restype = None
+    libtaos.taos_connect.restype = ctypes.c_void_p
+    libtaos.taos_use_result.restype = ctypes.c_void_p
+    libtaos.taos_fetch_row.restype = ctypes.POINTER(ctypes.c_void_p)
+    libtaos.taos_errstr.restype = ctypes.c_char_p
+    libtaos.taos_subscribe.restype = ctypes.c_void_p
+    libtaos.taos_consume.restype = ctypes.c_void_p
+
+    def __init__(self, config=None):
+        '''
+        Function to initialize the class
+        @host     : str, hostname to connect
+        @user     : str, username to connect to server
+        @password : str, password to connect to server
+        @db       : str, default db to use when log in
+        @config   : str, config directory
+
+        @rtype    : None
+        '''
+        if config is None:
+            self._config = ctypes.c_char_p(None)
+        else:
+            try:
+                self._config = ctypes.c_char_p(config.encode('utf-8'))
+            except AttributeError:
+                raise AttributeError("config is expected as a str")
+
+        if config != None:
+            CTaosInterface.libtaos.taos_options(3, self._config)
+
+        CTaosInterface.libtaos.taos_init()
+
+    @property
+    def config(self):
+        """ Get current config
+        """
+        return self._config
+
+    def connect(self, host=None, user="root", password="taosdata", db=None, port=0):
+        '''
+        Function to connect to server
+
+        @rtype: c_void_p, TDengine handle
+        '''
+        # host
+        try:
+            _host = ctypes.c_char_p(host.encode(
+                "utf-8")) if host != None else ctypes.c_char_p(None)
+        except AttributeError:
+            raise AttributeError("host is expected as a str")
+
+        # user
+        try:
+            _user = ctypes.c_char_p(user.encode("utf-8"))
+        except AttributeError:
+            raise AttributeError("user is expected as a str")
+
+        # password
+        try:
+            _password = ctypes.c_char_p(password.encode("utf-8"))
+        except AttributeError:
+            raise AttributeError("password is expected as a str")
+
+        # db
+        try:
+            _db = ctypes.c_char_p(
+                db.encode("utf-8")) if db != None else ctypes.c_char_p(None)
+        except AttributeError:
+            raise AttributeError("db is expected as a str")
+
+        # port
+        try:
+            _port = ctypes.c_int(port)
+        except TypeError:
+            raise TypeError("port is expected as an int")
+
+        connection = ctypes.c_void_p(CTaosInterface.libtaos.taos_connect(
+            _host, _user, _password, _db, _port))
+
+        if connection.value == None:
+            print('connect to TDengine failed')
+            # sys.exit(1)
+        else:
+            print('connect to TDengine success')
+
+        return connection
+
+    @staticmethod
+    def close(connection):
+        '''Close the TDengine handle
+        '''
+        CTaosInterface.libtaos.taos_close(connection)
+        print('connection is closed')
+
+    @staticmethod
+    def query(connection, sql):
+        '''Run SQL
+
+        @sql: str, sql string to run
+
+        @rtype: 0 on success and -1 on failure
+        '''
+        try:
+            return CTaosInterface.libtaos.taos_query(connection, ctypes.c_char_p(sql.encode('utf-8')))
+        except AttributeError:
+            raise AttributeError("sql is expected as a string")
+        # finally:
+        #     CTaosInterface.libtaos.close(connection)
+
+    @staticmethod
+    def affectedRows(connection):
+        """The affected rows after runing query
+        """
+        return CTaosInterface.libtaos.taos_affected_rows(connection)
+
+    @staticmethod
+    def subscribe(connection, restart, topic, sql, interval):
+        """Create a subscription
+         @restart boolean, 
+         @sql string, sql statement for data query, must be a 'select' statement.
+         @topic string, name of this subscription
+        """
+        return ctypes.c_void_p(CTaosInterface.libtaos.taos_subscribe(
+            connection,
+            1 if restart else 0,
+            ctypes.c_char_p(topic.encode('utf-8')),
+            ctypes.c_char_p(sql.encode('utf-8')),
+            None,
+            None,
+            interval))
+
+    @staticmethod
+    def consume(sub):
+        """Consume data of a subscription
+        """
+        result = ctypes.c_void_p(CTaosInterface.libtaos.taos_consume(sub))
+        fields = []
+        pfields = CTaosInterface.fetchFields(result)
+        for i in range(CTaosInterface.libtaos.taos_num_fields(result)):
+            fields.append({'name': pfields[i].name.decode('utf-8'),
+                           'bytes': pfields[i].bytes,
+                           'type': ord(pfields[i].type)})
+        return result, fields
+
+    @staticmethod
+    def unsubscribe(sub, keepProgress):
+        """Cancel a subscription
+        """
+        CTaosInterface.libtaos.taos_unsubscribe(sub, 1 if keepProgress else 0)
+
+    @staticmethod
+    def useResult(connection):
+        '''Use result after calling self.query
+        '''
+        result = ctypes.c_void_p(CTaosInterface.libtaos.taos_use_result(connection))
+        fields = []
+        pfields = CTaosInterface.fetchFields(result)
+        for i in range(CTaosInterface.fieldsCount(connection)):
+            fields.append({'name': pfields[i].name.decode('utf-8'),
+                           'bytes': pfields[i].bytes,
+                           'type': ord(pfields[i].type)})
+
+        return result, fields
+
+    @staticmethod
+    def fetchBlock(result, fields):
+        pblock = ctypes.c_void_p(0)
+        num_of_rows = CTaosInterface.libtaos.taos_fetch_block(
+            result, ctypes.byref(pblock))
+
+        if num_of_rows == 0:
+            return None, 0
+
+        isMicro = (CTaosInterface.libtaos.taos_result_precision(result) == FieldType.C_TIMESTAMP_MICRO)
+        blocks = [None] * len(fields)
+        for i in range(len(fields)):
+            data = ctypes.cast(pblock, ctypes.POINTER(ctypes.c_void_p))[i]
+
+            if fields[i]['type'] not in _CONVERT_FUNC:
+                raise DatabaseError("Invalid data type returned from database")
+            
+            blocks[i] = _CONVERT_FUNC[fields[i]['type']](data, num_of_rows, fields[i]['bytes'], isMicro)
+
+        return blocks, abs(num_of_rows)
+
+    @staticmethod
+    def freeResult(result):
+        CTaosInterface.libtaos.taos_free_result(result)
+        result.value = None
+
+    @staticmethod
+    def fieldsCount(connection):
+        return CTaosInterface.libtaos.taos_field_count(connection)
+
+    @staticmethod
+    def fetchFields(result):
+        return CTaosInterface.libtaos.taos_fetch_fields(result)
+
+    # @staticmethod
+    # def fetchRow(result, fields):
+    #     l = []
+    #     row = CTaosInterface.libtaos.taos_fetch_row(result)
+    #     if not row:
+    #         return None
+
+    #     for i in range(len(fields)):
+    #         l.append(CTaosInterface.getDataValue(
+    #             row[i], fields[i]['type'], fields[i]['bytes']))
+
+    #     return tuple(l)
+
+    # @staticmethod
+    # def getDataValue(data, dtype, byte):
+    #     '''
+    #     '''
+    #     if not data:
+    #         return None
+
+    #     if (dtype == CTaosInterface.TSDB_DATA_TYPE_BOOL):
+    #         return ctypes.cast(data,  ctypes.POINTER(ctypes.c_bool))[0]
+    #     elif (dtype == CTaosInterface.TSDB_DATA_TYPE_TINYINT):
+    #         return ctypes.cast(data,  ctypes.POINTER(ctypes.c_byte))[0]
+    #     elif (dtype == CTaosInterface.TSDB_DATA_TYPE_SMALLINT):
+    #         return ctypes.cast(data,  ctypes.POINTER(ctypes.c_short))[0]
+    #     elif (dtype == CTaosInterface.TSDB_DATA_TYPE_INT):
+    #         return ctypes.cast(data,  ctypes.POINTER(ctypes.c_int))[0]
+    #     elif (dtype == CTaosInterface.TSDB_DATA_TYPE_BIGINT):
+    #         return ctypes.cast(data,  ctypes.POINTER(ctypes.c_long))[0]
+    #     elif (dtype == CTaosInterface.TSDB_DATA_TYPE_FLOAT):
+    #         return ctypes.cast(data,  ctypes.POINTER(ctypes.c_float))[0]
+    #     elif (dtype == CTaosInterface.TSDB_DATA_TYPE_DOUBLE):
+    #         return ctypes.cast(data,  ctypes.POINTER(ctypes.c_double))[0]
+    #     elif (dtype == CTaosInterface.TSDB_DATA_TYPE_BINARY):
+    #         return (ctypes.cast(data,  ctypes.POINTER(ctypes.c_char))[0:byte]).rstrip('\x00')
+    #     elif (dtype == CTaosInterface.TSDB_DATA_TYPE_TIMESTAMP):
+    #         return ctypes.cast(data,  ctypes.POINTER(ctypes.c_long))[0]
+    #     elif (dtype == CTaosInterface.TSDB_DATA_TYPE_NCHAR):
+    #         return (ctypes.cast(data,  ctypes.c_char_p).value).rstrip('\x00')
+
+    @staticmethod
+    def errno(connection):
+        """Return the error number.
+        """
+        return CTaosInterface.libtaos.taos_errno(connection)
+
+    @staticmethod
+    def errStr(connection):
+        """Return the error styring
+        """
+        return CTaosInterface.libtaos.taos_errstr(connection).decode('utf-8')
+
+
+if __name__ == '__main__':
+    cinter = CTaosInterface()
+    conn = cinter.connect()
+
+    print('Query return value: {}'.format(cinter.query(conn, 'show databases')))
+    print('Affected rows: {}'.format(cinter.affectedRows(conn)))
+
+    result, des = CTaosInterface.useResult(conn)
+
+    data, num_of_rows = CTaosInterface.fetchBlock(result, des)
+
+    print(data)
+
     cinter.close(conn)
\ No newline at end of file
diff --git a/src/connector/python/windows/python3/taos/connection.py b/src/connector/python/windows/python3/taos/connection.py
index a88e25a6db..e2783975d9 100644
--- a/src/connector/python/windows/python3/taos/connection.py
+++ b/src/connector/python/windows/python3/taos/connection.py
@@ -1,81 +1,89 @@
-# from .cursor import TDengineCursor
-from .cursor import TDengineCursor
-from .cinterface import CTaosInterface
-
-class TDengineConnection(object):
-    """ TDengine connection object
-    """
-    def __init__(self, *args, **kwargs):
-        self._conn = None
-        self._host = None
-        self._user = "root"
-        self._password = "taosdata"
-        self._database = None
-        self._port = 0
-        self._config = None
-        self._chandle = None
-
-        if len(kwargs) > 0:
-            self.config(**kwargs)
-
-    def config(self, **kwargs):
-        # host
-        if 'host' in kwargs:
-            self._host = kwargs['host']
-
-        # user
-        if 'user' in kwargs:
-            self._user = kwargs['user']
-
-        # password
-        if 'password' in kwargs:
-            self._password = kwargs['password']
-        
-        # database
-        if 'database' in kwargs:
-            self._database = kwargs['database']
-
-        # port
-        if 'port' in kwargs:
-            self._port = kwargs['port']
-
-        # config
-        if 'config' in kwargs:
-            self._config = kwargs['config']
-
-        self._chandle = CTaosInterface(self._config)
-        self._conn = self._chandle.connect(self._host, self._user, self._password, self._database, self._port)
-
-    def close(self):
-        """Close current connection.
-        """
-        return CTaosInterface.close(self._conn)
-
-    def cursor(self):
-        """Return a new Cursor object using the connection.
-        """
-        return TDengineCursor(self)
-
-    def commit(self):
-        """Commit any pending transaction to the database.
-
-        Since TDengine do not support transactions, the implement is void functionality.
-        """
-        pass
-
-    def rollback(self):
-        """Void functionality
-        """
-        pass
-
-    def clear_result_set(self):
-        """Clear unused result set on this connection.
-        """
-        result = self._chandle.useResult(self._conn)[0]
-        if result:
-            self._chandle.freeResult(result)
-
-if __name__ == "__main__":
-    conn = TDengineConnection(host='192.168.1.107')
-    conn.close()
+from .cursor import TDengineCursor
+from .subscription import TDengineSubscription
+from .cinterface import CTaosInterface
+
+class TDengineConnection(object):
+    """ TDengine connection object
+    """
+    def __init__(self, *args, **kwargs):
+        self._conn = None
+        self._host = None
+        self._user = "root"
+        self._password = "taosdata"
+        self._database = None
+        self._port = 0
+        self._config = None
+        self._chandle = None
+
+        if len(kwargs) > 0:
+            self.config(**kwargs)
+
+    def config(self, **kwargs):
+        # host
+        if 'host' in kwargs:
+            self._host = kwargs['host']
+
+        # user
+        if 'user' in kwargs:
+            self._user = kwargs['user']
+
+        # password
+        if 'password' in kwargs:
+            self._password = kwargs['password']
+        
+        # database
+        if 'database' in kwargs:
+            self._database = kwargs['database']
+
+        # port
+        if 'port' in kwargs:
+            self._port = kwargs['port']
+
+        # config
+        if 'config' in kwargs:
+            self._config = kwargs['config']
+
+        self._chandle = CTaosInterface(self._config)
+        self._conn = self._chandle.connect(self._host, self._user, self._password, self._database, self._port)
+
+    def close(self):
+        """Close current connection.
+        """
+        return CTaosInterface.close(self._conn)
+
+    def subscribe(self, restart, topic, sql, interval):
+        """Create a subscription.
+        """
+        if self._conn is None:
+            return None
+        sub = CTaosInterface.subscribe(self._conn, restart, topic, sql, interval)
+        return TDengineSubscription(sub)
+
+    def cursor(self):
+        """Return a new Cursor object using the connection.
+        """
+        return TDengineCursor(self)
+
+    def commit(self):
+        """Commit any pending transaction to the database.
+
+        Since TDengine do not support transactions, the implement is void functionality.
+        """
+        pass
+
+    def rollback(self):
+        """Void functionality
+        """
+        pass
+
+    def clear_result_set(self):
+        """Clear unused result set on this connection.
+        """
+        result = self._chandle.useResult(self._conn)[0]
+        if result:
+            self._chandle.freeResult(result)
+
+if __name__ == "__main__":
+    conn = TDengineConnection(host='192.168.1.107')
+    conn.close()
     print("Hello world")
\ No newline at end of file
diff --git a/src/connector/python/windows/python3/taos/subscription.py b/src/connector/python/windows/python3/taos/subscription.py
new file mode 100644
index 0000000000..3af989a138
--- /dev/null
+++ b/src/connector/python/windows/python3/taos/subscription.py
@@ -0,0 +1,52 @@
+from .cinterface import CTaosInterface
+from .error import *
+
+class TDengineSubscription(object):
+    """TDengine subscription object
+    """
+    def __init__(self, sub):
+        self._sub = sub
+
+
+    def consume(self):
+        """Consume rows of a subscription
+        """
+        if self._sub is None:
+            raise OperationalError("Invalid use of consume")
+        
+        result, fields = CTaosInterface.consume(self._sub)
+        buffer = [[] for i in range(len(fields))]
+        print(buffer)
+        while True:
+            block, num_of_fields = CTaosInterface.fetchBlock(result, fields)
+            if num_of_fields == 0: break
+            for i in range(len(fields)):
+                buffer[i].extend(block[i])
+
+        return list(map(tuple, zip(*buffer)))
+
+
+    def close(self, keepProgress = True):
+        """Close the Subscription.
+        """
+        if self._sub is None:
+            return False
+
+        CTaosInterface.unsubscribe(self._sub, keepProgress)
+        return True
+
+
+if __name__ == '__main__':
+    from .connection import TDengineConnection
+    conn = TDengineConnection(host="127.0.0.1", user="root", password="taosdata", database="test")
+
+    # Generate a cursor object to run SQL commands
+    sub = conn.subscribe(True, "test", "select * from meters;", 1000)
+
+    for i in range(0,10):
+        data = sub.consume()
+        for d in data:
+            print(d)
+
+    sub.close()
+    conn.close()
\ No newline at end of file

From bea87b34f10047170b61aba0bba1566a4542cf9e Mon Sep 17 00:00:00 2001
From: localvar <localvar@hotmail.com>
Date: Thu, 16 Jan 2020 16:57:25 +0800
Subject: [PATCH 19/35] subscribe: fix bugs found in test

---
 src/client/src/tscServer.c   |  1 -
 src/client/src/tscSub.c      | 63 ++++++++++++++++++----------
 tests/examples/c/subscribe.c | 81 +++++++++++++++++++++++-------------
 3 files changed, 91 insertions(+), 54 deletions(-)

diff --git a/src/client/src/tscServer.c b/src/client/src/tscServer.c
index 0972e5fe2d..af914f9266 100644
--- a/src/client/src/tscServer.c
+++ b/src/client/src/tscServer.c
@@ -3558,7 +3558,6 @@ int tscProcessRetrieveRspFromVnode(SSqlObj *pSql) {
       p += sizeof(TSKEY);
       tscUpdateSubscriptionProgress(pSql->pSubscription, uid, key);
     }
-    tscSaveSubscriptionProgress(pSql->pSubscription);
   }
 
   pRes->row = 0;
diff --git a/src/client/src/tscSub.c b/src/client/src/tscSub.c
index 17a5031fa6..2d85c026af 100644
--- a/src/client/src/tscSub.c
+++ b/src/client/src/tscSub.c
@@ -49,7 +49,11 @@ typedef struct SSub {
 
 
 static int tscCompareSubscriptionProgress(const void* a, const void* b) {
-  return ((const SSubscriptionProgress*)a)->uid - ((const SSubscriptionProgress*)b)->uid;
+  const SSubscriptionProgress* x = (const SSubscriptionProgress*)a;
+  const SSubscriptionProgress* y = (const SSubscriptionProgress*)b;
+  if (x->uid > y->uid) return 1;
+  if (x->uid < y->uid) return -1;
+  return 0;
 }
 
 TSKEY tscGetSubscriptionProgress(void* sub, int64_t uid) {
@@ -175,7 +179,7 @@ int tscUpdateSubscription(STscObj* pObj, SSub* pSub) {
   if (!UTIL_METER_IS_NOMRAL_METER(pMeterMetaInfo)) {
     SMetricMeta* pMetricMeta = pMeterMetaInfo->pMetricMeta;
     for (int32_t i = 0; i < pMetricMeta->numOfVnodes; i++) {
-      SVnodeSidList *pVnodeSidList = tscGetVnodeSidList(pMetricMeta, pMeterMetaInfo->vnodeIndex);
+      SVnodeSidList *pVnodeSidList = tscGetVnodeSidList(pMetricMeta, i);
       numOfMeters += pVnodeSidList->numOfSids;
     }
   }
@@ -195,7 +199,7 @@ int tscUpdateSubscription(STscObj* pObj, SSub* pSub) {
     SMetricMeta* pMetricMeta = pMeterMetaInfo->pMetricMeta;
     numOfMeters = 0;
     for (int32_t i = 0; i < pMetricMeta->numOfVnodes; i++) {
-      SVnodeSidList *pVnodeSidList = tscGetVnodeSidList(pMetricMeta, pMeterMetaInfo->vnodeIndex);
+      SVnodeSidList *pVnodeSidList = tscGetVnodeSidList(pMetricMeta, i);
       for (int32_t j = 0; j < pVnodeSidList->numOfSids; j++) {
         SMeterSidExtInfo *pMeterInfo = tscGetMeterSidInfo(pVnodeSidList, j);
         int64_t uid = pMeterInfo->uid;
@@ -344,6 +348,8 @@ TAOS_RES *taos_consume(TAOS_SUB *tsub) {
   SSub *pSub = (SSub *)tsub;
   if (pSub == NULL) return NULL;
 
+  tscSaveSubscriptionProgress(pSub);
+
   SSqlObj* pSql = pSub->pSql;
   SSqlRes *pRes = &pSql->res;
 
@@ -355,27 +361,36 @@ TAOS_RES *taos_consume(TAOS_SUB *tsub) {
     }
   }
 
-  if (taosGetTimestampMs() - pSub->lastSyncTime > 10 * 60 * 1000) {
-    tscTrace("begin meter synchronization");
-    char* sqlstr = pSql->sqlstr;
-    pSql->sqlstr = NULL;
-    taos_free_result_imp(pSql, 0);
-    pSql->sqlstr = sqlstr;
-    taosClearDataCache(tscCacheHandle);
-    if (!tscUpdateSubscription(pSub->taos, pSub)) return NULL;
-    tscTrace("meter synchronization completed");
-  } else {
-    uint16_t type = pSql->cmd.type;
-    taos_free_result_imp(pSql, 1);
-    pRes->numOfRows = 1;
-    pRes->numOfTotal = 0;
-    pRes->qhandle = 0;
-    pSql->thandle = NULL;
-    pSql->cmd.command = TSDB_SQL_SELECT;
-    pSql->cmd.type = type;
+  for (int retry = 0; retry < 3; retry++) {
+    if (taosGetTimestampMs() - pSub->lastSyncTime > 10 * 60 * 1000) {
+      tscTrace("begin meter synchronization");
+      char* sqlstr = pSql->sqlstr;
+      pSql->sqlstr = NULL;
+      taos_free_result_imp(pSql, 0);
+      pSql->sqlstr = sqlstr;
+      taosClearDataCache(tscCacheHandle);
+      if (!tscUpdateSubscription(pSub->taos, pSub)) return NULL;
+      tscTrace("meter synchronization completed");
+    } else {
+      uint16_t type = pSql->cmd.type;
+      taos_free_result_imp(pSql, 1);
+      pRes->numOfRows = 1;
+      pRes->numOfTotal = 0;
+      pRes->qhandle = 0;
+      pSql->thandle = NULL;
+      pSql->cmd.command = TSDB_SQL_SELECT;
+      pSql->cmd.type = type;
+    }
+
+    tscDoQuery(pSql);
+    if (pRes->code != TSDB_CODE_NOT_ACTIVE_TABLE) {
+      break;
+    }
+    // meter was removed, make sync time zero, so that next retry will
+    // do synchronization first
+    pSub->lastSyncTime = 0;
   }
 
-  tscDoQuery(pSql);
   if (pRes->code != TSDB_CODE_SUCCESS) {
     tscError("failed to query data, error code=%d", pRes->code);
     tscRemoveFromSqlList(pSql);
@@ -394,7 +409,9 @@ void taos_unsubscribe(TAOS_SUB *tsub, int keepProgress) {
     taosTmrStop(pSub->pTimer);
   }
 
-  if (!keepProgress) {
+  if (keepProgress) {
+    tscSaveSubscriptionProgress(pSub);
+  } else {
     char path[256];
     sprintf(path, "%s/subscribe/%s", dataDir, pSub->topic);
     remove(path);
diff --git a/tests/examples/c/subscribe.c b/tests/examples/c/subscribe.c
index 04d000ba37..b168648702 100644
--- a/tests/examples/c/subscribe.c
+++ b/tests/examples/c/subscribe.c
@@ -7,33 +7,30 @@
 #include <taos.h>  // include TDengine header file
 #include <unistd.h>
 
-void print_result(TAOS_RES* res) {
+void print_result(TAOS_RES* res, int blockFetch) {
   TAOS_ROW    row = NULL;
   int         num_fields = taos_num_fields(res);
   TAOS_FIELD* fields = taos_fetch_fields(res);
 
-#if 0
-
-  int nRows = taos_fetch_block(res, &row);
-  for (int i = 0; i < nRows; i++) {
-    char temp[256];
-    taos_print_row(temp, row + i, fields, num_fields);
-    puts(temp);
+  if (blockFetch) {
+    int nRows = taos_fetch_block(res, &row);
+    for (int i = 0; i < nRows; i++) {
+      char temp[256];
+      taos_print_row(temp, row + i, fields, num_fields);
+      puts(temp);
+    }
+  } else {
+    while ((row = taos_fetch_row(res))) {
+      char temp[256];
+      taos_print_row(temp, row, fields, num_fields);
+      puts(temp);
+    }
   }
-
-#else
-
-  while ((row = taos_fetch_row(res))) {
-    char temp[256];
-    taos_print_row(temp, row, fields, num_fields);
-    puts(temp);
-  }
-
-#endif
 }
 
+
 void subscribe_callback(TAOS_SUB* tsub, TAOS_RES *res, void* param, int code) {
-  print_result(res);
+  print_result(res, *(int*)param);
 }
 
 
@@ -50,11 +47,12 @@ void check_row_count(int line, TAOS_RES* res, int expected) {
   }
 }
 
+
 void run_test(TAOS* taos) {
   taos_query(taos, "drop database test;");
   
   usleep(100000);
-  taos_query(taos, "create database test;");
+  taos_query(taos, "create database test tables 5;");
   usleep(100000);
   taos_query(taos, "use test;");
   usleep(100000);
@@ -71,12 +69,19 @@ void run_test(TAOS* taos) {
   taos_query(taos, "insert into t2 using meters tags('london', 0) values('2020-01-01 00:01:00.000', 0, 'UK');");
   taos_query(taos, "insert into t2 using meters tags('london', 0) values('2020-01-01 00:01:01.000', 0, 'UK');");
   taos_query(taos, "insert into t2 using meters tags('london', 0) values('2020-01-01 00:01:02.000', 0, 'UK');");
+  taos_query(taos, "insert into t3 using meters tags('tianjin', 0) values('2020-01-01 00:01:02.000', 0, 'china');");
+  taos_query(taos, "insert into t4 using meters tags('wuhan', 0) values('2020-01-01 00:01:02.000', 0, 'china');");
+  taos_query(taos, "insert into t5 using meters tags('jinan', 0) values('2020-01-01 00:01:02.000', 0, 'china');");
+  taos_query(taos, "insert into t6 using meters tags('haikou', 0) values('2020-01-01 00:01:02.000', 0, 'china');");
+  taos_query(taos, "insert into t7 using meters tags('nanjing', 0) values('2020-01-01 00:01:02.000', 0, 'china');");
+  taos_query(taos, "insert into t8 using meters tags('lanzhou', 0) values('2020-01-01 00:01:02.000', 0, 'china');");
+  taos_query(taos, "insert into t9 using meters tags('tokyo', 0) values('2020-01-01 00:01:02.000', 0, 'japan');");
 
   // super tables subscription
 
   TAOS_SUB* tsub = taos_subscribe(taos, 0, "test", "select * from meters;", NULL, NULL, 0);
   TAOS_RES* res = taos_consume(tsub);
-  check_row_count(__LINE__, res, 11);
+  check_row_count(__LINE__, res, 18);
 
   res = taos_consume(tsub);
   check_row_count(__LINE__, res, 0);
@@ -90,18 +95,24 @@ void run_test(TAOS* taos) {
   res = taos_consume(tsub);
   check_row_count(__LINE__, res, 1);
 
-  // keep progress information and continue previous subscription
+  // keep progress information and restart subscription
   taos_unsubscribe(tsub, 1);
   taos_query(taos, "insert into t0 using meters tags('beijing', 0) values('2020-01-01 00:03:00.000', 0, 'china');");
   tsub = taos_subscribe(taos, 1, "test", "select * from meters;", NULL, NULL, 0);
   res = taos_consume(tsub);
-  check_row_count(__LINE__, res, 15);
+  check_row_count(__LINE__, res, 22);
+
+  // keep progress information and continue previous subscription
+  taos_unsubscribe(tsub, 1);
+  tsub = taos_subscribe(taos, 0, "test", "select * from meters;", NULL, NULL, 0);
+  res = taos_consume(tsub);
+  check_row_count(__LINE__, res, 0);
 
   // don't keep progress information and continue previous subscription
   taos_unsubscribe(tsub, 0);
   tsub = taos_subscribe(taos, 0, "test", "select * from meters;", NULL, NULL, 0);
   res = taos_consume(tsub);
-  check_row_count(__LINE__, res, 15);
+  check_row_count(__LINE__, res, 22);
 
   // single meter subscription
 
@@ -132,8 +143,7 @@ int main(int argc, char *argv[]) {
   const char* passwd = "taosdata";
   const char* sql = "select * from meters;";
   const char* topic = "test-multiple";
-  int async = 1, restart = 0, keep = 1, test = 0;
-  TAOS_SUB* tsub = NULL;
+  int async = 1, restart = 0, keep = 1, test = 0, blockFetch = 0;
 
   for (int i = 1; i < argc; i++) {
     if (strncmp(argv[i], "-h=", 3) == 0) {
@@ -174,6 +184,10 @@ int main(int argc, char *argv[]) {
       test = 1;
       continue;
     }
+    if (strcmp(argv[i], "-block-fetch") == 0) {
+      blockFetch = 1;
+      continue;
+    }
   }
 
   // init TAOS
@@ -191,9 +205,12 @@ int main(int argc, char *argv[]) {
     exit(0);
   }
 
+  TAOS_SUB* tsub = NULL;
   if (async) {
-    tsub = taos_subscribe(taos, restart, topic, sql, subscribe_callback, NULL, 1000);
+    // create an asynchronized subscription, the callback function will be called every 1s
+    tsub = taos_subscribe(taos, restart, topic, sql, subscribe_callback, &blockFetch, 1000);
   } else {
+    // create an synchronized subscription, need to call 'taos_consume' manually
     tsub = taos_subscribe(taos, restart, topic, sql, NULL, NULL, 0);
   }
 
@@ -206,8 +223,13 @@ int main(int argc, char *argv[]) {
     getchar();
   } else while(1) {
     TAOS_RES* res = taos_consume(tsub);
-    print_result(res);
-    getchar();
+    if (res == NULL) {
+      printf("failed to consume data.");
+      break;
+    } else {
+      print_result(res, blockFetch);
+      getchar();
+    }
   }
 
   taos_unsubscribe(tsub, keep);
@@ -215,4 +237,3 @@ int main(int argc, char *argv[]) {
 
   return 0;
 }
-

From fa8baf802285f28896e05212ffa6766d0e272aac Mon Sep 17 00:00:00 2001
From: localvar <localvar@hotmail.com>
Date: Thu, 16 Jan 2020 16:58:13 +0800
Subject: [PATCH 20/35] subscribe: remove testing code from python connector

---
 src/connector/python/linux/python2/taos/subscription.py   | 2 +-
 src/connector/python/linux/python3/taos/subscription.py   | 2 +-
 src/connector/python/windows/python2/taos/subscription.py | 2 +-
 src/connector/python/windows/python3/taos/subscription.py | 2 +-
 4 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/src/connector/python/linux/python2/taos/subscription.py b/src/connector/python/linux/python2/taos/subscription.py
index cbba3d59ca..2d01395532 100644
--- a/src/connector/python/linux/python2/taos/subscription.py
+++ b/src/connector/python/linux/python2/taos/subscription.py
@@ -16,13 +16,13 @@ class TDengineSubscription(object):
         
         result, fields = CTaosInterface.consume(self._sub)
         buffer = [[] for i in range(len(fields))]
-        print(buffer)
         while True:
             block, num_of_fields = CTaosInterface.fetchBlock(result, fields)
             if num_of_fields == 0: break
             for i in range(len(fields)):
                 buffer[i].extend(block[i])
 
+        self.fields = fields
         return list(map(tuple, zip(*buffer)))
 
 
diff --git a/src/connector/python/linux/python3/taos/subscription.py b/src/connector/python/linux/python3/taos/subscription.py
index 3af989a138..d3cf10d5ad 100644
--- a/src/connector/python/linux/python3/taos/subscription.py
+++ b/src/connector/python/linux/python3/taos/subscription.py
@@ -16,13 +16,13 @@ class TDengineSubscription(object):
         
         result, fields = CTaosInterface.consume(self._sub)
         buffer = [[] for i in range(len(fields))]
-        print(buffer)
         while True:
             block, num_of_fields = CTaosInterface.fetchBlock(result, fields)
             if num_of_fields == 0: break
             for i in range(len(fields)):
                 buffer[i].extend(block[i])
 
+        self.fields = fields
         return list(map(tuple, zip(*buffer)))
 
 
diff --git a/src/connector/python/windows/python2/taos/subscription.py b/src/connector/python/windows/python2/taos/subscription.py
index 3af989a138..d3cf10d5ad 100644
--- a/src/connector/python/windows/python2/taos/subscription.py
+++ b/src/connector/python/windows/python2/taos/subscription.py
@@ -16,13 +16,13 @@ class TDengineSubscription(object):
         
         result, fields = CTaosInterface.consume(self._sub)
         buffer = [[] for i in range(len(fields))]
-        print(buffer)
         while True:
             block, num_of_fields = CTaosInterface.fetchBlock(result, fields)
             if num_of_fields == 0: break
             for i in range(len(fields)):
                 buffer[i].extend(block[i])
 
+        self.fields = fields
         return list(map(tuple, zip(*buffer)))
 
 
diff --git a/src/connector/python/windows/python3/taos/subscription.py b/src/connector/python/windows/python3/taos/subscription.py
index 3af989a138..d3cf10d5ad 100644
--- a/src/connector/python/windows/python3/taos/subscription.py
+++ b/src/connector/python/windows/python3/taos/subscription.py
@@ -16,13 +16,13 @@ class TDengineSubscription(object):
         
         result, fields = CTaosInterface.consume(self._sub)
         buffer = [[] for i in range(len(fields))]
-        print(buffer)
         while True:
             block, num_of_fields = CTaosInterface.fetchBlock(result, fields)
             if num_of_fields == 0: break
             for i in range(len(fields)):
                 buffer[i].extend(block[i])
 
+        self.fields = fields
         return list(map(tuple, zip(*buffer)))
 
 

From c48c78e6ee47986a1b62b76339acb592c963ca29 Mon Sep 17 00:00:00 2001
From: fangpanpan <fpang@taosdata.com>
Date: Fri, 17 Jan 2020 09:38:14 +0800
Subject: [PATCH 21/35] [update release info]

---
 src/util/src/version.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/src/util/src/version.c b/src/util/src/version.c
index c85289fb8a..205b626656 100644
--- a/src/util/src/version.c
+++ b/src/util/src/version.c
@@ -1,5 +1,5 @@
-char version[64] = "1.6.4.4";
+char version[64] = "1.6.4.6";
 char compatible_version[64] = "1.6.1.0";
-char gitinfo[128] = "d62c5c30231d04a736d437cf428af6e12599bd9f";
-char gitinfoOfInternal[128] = "8094a32d78dc519bd883d01ac2ba6ec49ac57a80";
-char buildinfo[512] = "Built by ubuntu at 2019-12-16 21:40";
+char gitinfo[128] = "0d2351b4a7043f4e907734d7b1696d13574cb8e0";
+char gitinfoOfInternal[128] = "a898ecfc1f6b9f1c626ca98a0b9a77b8d5b52abe";
+char buildinfo[512] = "Built by root at 2020-01-14 11:05";

From 35976735df767be187be9545b3303b048b995485 Mon Sep 17 00:00:00 2001
From: localvar <localvar@hotmail.com>
Date: Sat, 18 Jan 2020 14:43:29 +0800
Subject: [PATCH 22/35] subscribe: fix bug in multi-vnode subscription

---
 src/client/src/tscSub.c      |  4 ++++
 tests/examples/c/subscribe.c | 28 ++++++++++++++--------------
 2 files changed, 18 insertions(+), 14 deletions(-)

diff --git a/src/client/src/tscSub.c b/src/client/src/tscSub.c
index 2d85c026af..69d8fc447e 100644
--- a/src/client/src/tscSub.c
+++ b/src/client/src/tscSub.c
@@ -362,6 +362,8 @@ TAOS_RES *taos_consume(TAOS_SUB *tsub) {
   }
 
   for (int retry = 0; retry < 3; retry++) {
+    tscRemoveFromSqlList(pSql);
+
     if (taosGetTimestampMs() - pSub->lastSyncTime > 10 * 60 * 1000) {
       tscTrace("begin meter synchronization");
       char* sqlstr = pSql->sqlstr;
@@ -380,6 +382,8 @@ TAOS_RES *taos_consume(TAOS_SUB *tsub) {
       pSql->thandle = NULL;
       pSql->cmd.command = TSDB_SQL_SELECT;
       pSql->cmd.type = type;
+
+      tscGetMeterMetaInfo(&pSql->cmd, 0)->vnodeIndex = 0;
     }
 
     tscDoQuery(pSql);
diff --git a/tests/examples/c/subscribe.c b/tests/examples/c/subscribe.c
index b168648702..88ff223d7f 100644
--- a/tests/examples/c/subscribe.c
+++ b/tests/examples/c/subscribe.c
@@ -49,7 +49,7 @@ void check_row_count(int line, TAOS_RES* res, int expected) {
 
 
 void run_test(TAOS* taos) {
-  taos_query(taos, "drop database test;");
+  taos_query(taos, "drop database if exists test;");
   
   usleep(100000);
   taos_query(taos, "create database test tables 5;");
@@ -86,21 +86,26 @@ void run_test(TAOS* taos) {
   res = taos_consume(tsub);
   check_row_count(__LINE__, res, 0);
 
-  taos_query(taos, "insert into t2 using meters tags('london', 0) values('2020-01-01 00:01:02.001', 0, 'UK');");
-  taos_query(taos, "insert into t1 using meters tags('london', 0) values('2020-01-01 00:03:00.001', 0, 'UK');");
+  taos_query(taos, "insert into t0 values('2020-01-01 00:03:00.000', 0, 'china');");
+  taos_query(taos, "insert into t8 values('2020-01-01 00:01:03.000', 0, 'china');");
   res = taos_consume(tsub);
   check_row_count(__LINE__, res, 2);
 
-  taos_query(taos, "insert into t1 using meters tags('shanghai', 0) values('2020-01-01 00:03:00.002', 0, 'china');");
+  taos_query(taos, "insert into t2 values('2020-01-01 00:01:02.001', 0, 'UK');");
+  taos_query(taos, "insert into t1 values('2020-01-01 00:03:00.001', 0, 'UK');");
+  res = taos_consume(tsub);
+  check_row_count(__LINE__, res, 2);
+
+  taos_query(taos, "insert into t1 values('2020-01-01 00:03:00.002', 0, 'china');");
   res = taos_consume(tsub);
   check_row_count(__LINE__, res, 1);
 
   // keep progress information and restart subscription
   taos_unsubscribe(tsub, 1);
-  taos_query(taos, "insert into t0 using meters tags('beijing', 0) values('2020-01-01 00:03:00.000', 0, 'china');");
+  taos_query(taos, "insert into t0 values('2020-01-01 00:04:00.000', 0, 'china');");
   tsub = taos_subscribe(taos, 1, "test", "select * from meters;", NULL, NULL, 0);
   res = taos_consume(tsub);
-  check_row_count(__LINE__, res, 22);
+  check_row_count(__LINE__, res, 24);
 
   // keep progress information and continue previous subscription
   taos_unsubscribe(tsub, 1);
@@ -112,27 +117,22 @@ void run_test(TAOS* taos) {
   taos_unsubscribe(tsub, 0);
   tsub = taos_subscribe(taos, 0, "test", "select * from meters;", NULL, NULL, 0);
   res = taos_consume(tsub);
-  check_row_count(__LINE__, res, 22);
+  check_row_count(__LINE__, res, 24);
 
   // single meter subscription
 
   taos_unsubscribe(tsub, 0);
   tsub = taos_subscribe(taos, 0, "test", "select * from t0;", NULL, NULL, 0);
   res = taos_consume(tsub);
-  check_row_count(__LINE__, res, 4);
+  check_row_count(__LINE__, res, 5);
 
   res = taos_consume(tsub);
   check_row_count(__LINE__, res, 0);
 
-  taos_query(taos, "insert into t0 using meters tags('beijing', 0) values('2020-01-01 00:03:00.001', 0, 'china');");
+  taos_query(taos, "insert into t0 values('2020-01-01 00:04:00.001', 0, 'china');");
   res = taos_consume(tsub);
   check_row_count(__LINE__, res, 1);
 
-  taos_query(taos, "insert into t0 using meters tags('beijing', 0) values('2020-01-01 00:03:00.002', 0, 'china');");
-  taos_query(taos, "insert into t0 using meters tags('beijing', 0) values('2020-01-01 00:04:00.000', 0, 'china');");
-  res = taos_consume(tsub);
-  check_row_count(__LINE__, res, 2);
-
   taos_unsubscribe(tsub, 0);
 }
 

From 1f7a9e6764f57d34b548ac8249b3ad8b050beea7 Mon Sep 17 00:00:00 2001
From: localvar <localvar@hotmail.com>
Date: Sat, 18 Jan 2020 16:16:49 +0800
Subject: [PATCH 23/35] subscribe: minor improvement

revise progress persistent file format to reduce file size.
example: print out number of rows consumed
---
 src/client/src/tscSub.c      | 4 ++--
 tests/examples/c/subscribe.c | 6 +++++-
 2 files changed, 7 insertions(+), 3 deletions(-)

diff --git a/src/client/src/tscSub.c b/src/client/src/tscSub.c
index 69d8fc447e..8a2c8ae44e 100644
--- a/src/client/src/tscSub.c
+++ b/src/client/src/tscSub.c
@@ -265,7 +265,7 @@ static int tscLoadSubscriptionProgress(SSub* pSub) {
       return 0;
     }
     int64_t uid, key;
-    sscanf(buf, "uid=%" SCNd64 ",progress=%" SCNd64, &uid, &key);
+    sscanf(buf, "%" SCNd64 ":%" SCNd64, &uid, &key);
     progress[i].uid = uid;
     progress[i].key = key;
   }
@@ -300,7 +300,7 @@ void tscSaveSubscriptionProgress(void* sub) {
   for (int i = 0; i < pSub->numOfMeters; i++) {
     int64_t uid = pSub->progress[i].uid;
     TSKEY key = pSub->progress[i].key;
-    fprintf(fp, "uid=%" PRId64 ",progress=%" PRId64 "\n", uid, key);
+    fprintf(fp, "%" PRId64 ":%" PRId64 "\n", uid, key);
   }
 
   fclose(fp);
diff --git a/tests/examples/c/subscribe.c b/tests/examples/c/subscribe.c
index 88ff223d7f..0bf93f6f2d 100644
--- a/tests/examples/c/subscribe.c
+++ b/tests/examples/c/subscribe.c
@@ -11,9 +11,10 @@ void print_result(TAOS_RES* res, int blockFetch) {
   TAOS_ROW    row = NULL;
   int         num_fields = taos_num_fields(res);
   TAOS_FIELD* fields = taos_fetch_fields(res);
+  int         nRows = 0;
 
   if (blockFetch) {
-    int nRows = taos_fetch_block(res, &row);
+    nRows = taos_fetch_block(res, &row);
     for (int i = 0; i < nRows; i++) {
       char temp[256];
       taos_print_row(temp, row + i, fields, num_fields);
@@ -24,8 +25,11 @@ void print_result(TAOS_RES* res, int blockFetch) {
       char temp[256];
       taos_print_row(temp, row, fields, num_fields);
       puts(temp);
+      nRows++;
     }
   }
+
+  printf("%d rows consumed.\n", nRows);
 }
 
 

From 8da35ff159fec51f5baad49931fee3e86729c3b7 Mon Sep 17 00:00:00 2001
From: localvar <localvar@hotmail.com>
Date: Sat, 18 Jan 2020 16:48:04 +0800
Subject: [PATCH 24/35] subscribe: update python connector documentation.

---
 .../webdocs/markdowndocs/Connector.md         | 22 +++++++++++++++++++
 .../webdocs/markdowndocs/connector-ch.md      | 21 ++++++++++++++++++
 2 files changed, 43 insertions(+)

diff --git a/documentation/webdocs/markdowndocs/Connector.md b/documentation/webdocs/markdowndocs/Connector.md
index caedff4436..edda0e2196 100644
--- a/documentation/webdocs/markdowndocs/Connector.md
+++ b/documentation/webdocs/markdowndocs/Connector.md
@@ -598,6 +598,28 @@ c1.execute('select * from tb')
 for data in c1:
   print("ts=%s, temperature=%d, humidity=%f" %(data[0], data[1],data[2])
 ```
+
+* create a subscription
+```python
+# Create a subscription with topic 'test' and consumption interval 1000ms.
+# The first argument is True means to restart the subscription;
+# if the subscription with topic 'test' has already been created, then pass
+# False to this argument means to continue the existing subscription.
+sub = conn.subscribe(True, "test", "select * from meters;", 1000)
+```
+
+* consume a subscription
+```python
+data = sub.consume()
+for d in data:
+    print(d)
+```
+
+* close the subscription
+```python
+sub.close()
+```
+
 * close the connection
 ```python
 c1.close()
diff --git a/documentation/webdocs/markdowndocs/connector-ch.md b/documentation/webdocs/markdowndocs/connector-ch.md
index c9eaa8e63b..f84e1f367e 100644
--- a/documentation/webdocs/markdowndocs/connector-ch.md
+++ b/documentation/webdocs/markdowndocs/connector-ch.md
@@ -595,6 +595,27 @@ c1.execute('select * from tb')
 for data in c1:
   print("ts=%s, temperature=%d, humidity=%f" %(data[0], data[1],data[2])
 ```
+
+* 创建订阅
+```python
+# 创建一个主题为 'test' 消费周期为1000毫秒的订阅
+# 第一个参数为 True 表示重新开始订阅，如为 False 且之前创建过主题为 'test' 的订阅，则表示继续消费此订阅的数据，而不是重新开始消费所有数据
+sub = conn.subscribe(True, "test", "select * from meters;", 1000)
+```
+
+* 消费订阅的数据
+```python
+data = sub.consume()
+for d in data:
+    print(d)
+```
+
+* 取消订阅
+```python
+sub.close()
+```
+
+
 * 关闭连接
 ```python
 c1.close()

From c4d61438caf44ad9d2b50bf6d0c32a74f1fa18b3 Mon Sep 17 00:00:00 2001
From: hjxilinx <hjxilinx@163.com>
Date: Sat, 18 Jan 2020 18:23:56 +0800
Subject: [PATCH 25/35] fix memory leaks

---
 src/system/detail/src/vnodeQueryImpl.c    | 10 ++++----
 src/system/detail/src/vnodeQueryProcess.c | 28 ++++++++++-------------
 2 files changed, 17 insertions(+), 21 deletions(-)

diff --git a/src/system/detail/src/vnodeQueryImpl.c b/src/system/detail/src/vnodeQueryImpl.c
index 3158ecf15b..0daa0936e9 100644
--- a/src/system/detail/src/vnodeQueryImpl.c
+++ b/src/system/detail/src/vnodeQueryImpl.c
@@ -5980,12 +5980,12 @@ int32_t getDataBlocksForMeters(SMeterQuerySupportObj *pSupporter, SQuery *pQuery
     int32_t ret = validateCompBlockInfoSegment(pQInfo, filePath, pMeterObj->vnode, &compInfo,
                                                pMeterDataInfo[j]->offsetInHeaderFile);
     if (ret != TSDB_CODE_SUCCESS) {  // file corrupted
-      clearAllMeterDataBlockInfo(pMeterDataInfo, 0, j);
+      clearAllMeterDataBlockInfo(pMeterDataInfo, 0, numOfMeters);
       return TSDB_CODE_FILE_CORRUPTED;
     }
 
     if (compInfo.numOfBlocks <= 0 || compInfo.uid != pMeterDataInfo[j]->pMeterObj->uid) {
-      clearAllMeterDataBlockInfo(pMeterDataInfo, 0, j);
+      clearAllMeterDataBlockInfo(pMeterDataInfo, 0, numOfMeters);
       continue;
     }
   
@@ -5995,7 +5995,7 @@ int32_t getDataBlocksForMeters(SMeterQuerySupportObj *pSupporter, SQuery *pQuery
     pMeterDataInfo[j]->numOfBlocks = compInfo.numOfBlocks;
     pMeterDataInfo[j]->pBlock = calloc(1, bufferSize);
     if (pMeterDataInfo[j]->pBlock == NULL) {
-      clearAllMeterDataBlockInfo(pMeterDataInfo, 0, j);
+      clearAllMeterDataBlockInfo(pMeterDataInfo, 0, numOfMeters);
       return TSDB_CODE_SERV_OUT_OF_MEMORY;
     }
   
@@ -6007,7 +6007,7 @@ int32_t getDataBlocksForMeters(SMeterQuerySupportObj *pSupporter, SQuery *pQuery
     // check compblock integrity
     ret = validateCompBlockSegment(pQInfo, filePath, &compInfo, (char*) pMeterDataInfo[j]->pBlock, pMeterObj->vnode, checksum);
     if (ret != TSDB_CODE_SUCCESS) {
-      clearAllMeterDataBlockInfo(pMeterDataInfo, 0, j);
+      clearAllMeterDataBlockInfo(pMeterDataInfo, 0, numOfMeters);
       return TSDB_CODE_FILE_CORRUPTED;
     }
 
@@ -6031,7 +6031,7 @@ int32_t getDataBlocksForMeters(SMeterQuerySupportObj *pSupporter, SQuery *pQuery
     }
 
     if (!setValidDataBlocks(pMeterDataInfo[j], end)) {
-      clearAllMeterDataBlockInfo(pMeterDataInfo, 0, j);
+      clearAllMeterDataBlockInfo(pMeterDataInfo, 0, numOfMeters);
       
       pQInfo->killed = 1;  // set query kill, abort current query since no memory available
       return TSDB_CODE_SERV_OUT_OF_MEMORY;
diff --git a/src/system/detail/src/vnodeQueryProcess.c b/src/system/detail/src/vnodeQueryProcess.c
index c69b27537e..1783a1a0b4 100644
--- a/src/system/detail/src/vnodeQueryProcess.c
+++ b/src/system/detail/src/vnodeQueryProcess.c
@@ -85,7 +85,7 @@ static void setStartPositionForCacheBlock(SQuery *pQuery, SCacheBlock *pBlock, b
   }
 }
 
-static SMeterDataInfo *queryOnMultiDataCache(SQInfo *pQInfo, SMeterDataInfo *pMeterInfo) {
+static void queryOnMultiDataCache(SQInfo *pQInfo, SMeterDataInfo *pMeterInfo) {
   SQuery *               pQuery = &pQInfo->query;
   SMeterQuerySupportObj *pSupporter = pQInfo->pMeterQuerySupporter;
   SQueryRuntimeEnv *     pRuntimeEnv = &pQInfo->pMeterQuerySupporter->runtimeEnv;
@@ -107,7 +107,7 @@ static SMeterDataInfo *queryOnMultiDataCache(SQInfo *pQInfo, SMeterDataInfo *pMe
     int32_t end = pSupporter->pSidSet->starterPos[groupIdx + 1] - 1;
 
     if (isQueryKilled(pQuery)) {
-      return pMeterInfo;
+      return;
     }
 
     for (int32_t k = start; k <= end; ++k) {
@@ -160,7 +160,7 @@ static SMeterDataInfo *queryOnMultiDataCache(SQInfo *pQInfo, SMeterDataInfo *pMe
         int32_t ret = setIntervalQueryExecutionContext(pSupporter, k, pMeterQueryInfo);
         if (ret != TSDB_CODE_SUCCESS) {
           pQInfo->killed = 1;
-          return NULL;
+          return;
         }
       }
 
@@ -255,11 +255,9 @@ static SMeterDataInfo *queryOnMultiDataCache(SQInfo *pQInfo, SMeterDataInfo *pMe
   dTrace("QInfo:%p complete check %d cache blocks, elapsed time:%.3fms", pQInfo, totalBlocks, time / 1000.0);
 
   setQueryStatus(pQuery, QUERY_NOT_COMPLETED);
-
-  return pMeterInfo;
 }
 
-static SMeterDataInfo *queryOnMultiDataFiles(SQInfo *pQInfo, SMeterDataInfo *pMeterDataInfo) {
+static void queryOnMultiDataFiles(SQInfo *pQInfo, SMeterDataInfo *pMeterDataInfo) {
   SQuery *               pQuery = &pQInfo->query;
   SMeterQuerySupportObj *pSupporter = pQInfo->pMeterQuerySupporter;
   SQueryRuntimeEnv *     pRuntimeEnv = &pSupporter->runtimeEnv;
@@ -313,7 +311,7 @@ static SMeterDataInfo *queryOnMultiDataFiles(SQInfo *pQInfo, SMeterDataInfo *pMe
       pQInfo->code = -ret;
       pQInfo->killed = 1;
       
-      return NULL;
+      return;
     }
 
     dTrace("QInfo:%p file:%s, %d meters qualified", pQInfo, pVnodeFileInfo->dataFilePath, numOfQualifiedMeters);
@@ -335,7 +333,7 @@ static SMeterDataInfo *queryOnMultiDataFiles(SQInfo *pQInfo, SMeterDataInfo *pMe
       pQInfo->code = -ret;
       pQInfo->killed = 1;
   
-      return NULL;
+      return;
     }
 
     dTrace("QInfo:%p file:%s, %d meters contains %d blocks to be checked", pQInfo, pVnodeFileInfo->dataFilePath,
@@ -355,7 +353,7 @@ static SMeterDataInfo *queryOnMultiDataFiles(SQInfo *pQInfo, SMeterDataInfo *pMe
 
       pQInfo->code = -ret;
       pQInfo->killed = 1;
-      return NULL;
+      return;
     }
 
     dTrace("QInfo:%p start to load %d blocks and check", pQInfo, numOfBlocks);
@@ -412,7 +410,7 @@ static SMeterDataInfo *queryOnMultiDataFiles(SQInfo *pQInfo, SMeterDataInfo *pMe
         if (ret != TSDB_CODE_SUCCESS) {
           tfree(pReqMeterDataInfo);  // error code has been set
           pQInfo->killed = 1;
-          return NULL;
+          return;
         }
       }
 
@@ -461,8 +459,6 @@ static SMeterDataInfo *queryOnMultiDataFiles(SQInfo *pQInfo, SMeterDataInfo *pMe
 
   setQueryStatus(pQuery, QUERY_NOT_COMPLETED);
   freeMeterBlockInfoEx(pDataBlockInfoEx, nAllocBlocksInfoSize);
-
-  return pMeterDataInfo;
 }
 
 static bool multimeterMultioutputHelper(SQInfo *pQInfo, bool *dataInDisk, bool *dataInCache, int32_t index,
@@ -811,19 +807,19 @@ static void doOrderedScan(SQInfo *pQInfo) {
   SQuery *               pQuery = &pQInfo->query;
 
   if (QUERY_IS_ASC_QUERY(pQuery)) {
-    pSupporter->pMeterDataInfo = queryOnMultiDataFiles(pQInfo, pSupporter->pMeterDataInfo);
+    queryOnMultiDataFiles(pQInfo, pSupporter->pMeterDataInfo);
     if (pQInfo->code != TSDB_CODE_SUCCESS) {
       return;
     }
 
-    pSupporter->pMeterDataInfo = queryOnMultiDataCache(pQInfo, pSupporter->pMeterDataInfo);
+    queryOnMultiDataCache(pQInfo, pSupporter->pMeterDataInfo);
   } else {
-    pSupporter->pMeterDataInfo = queryOnMultiDataCache(pQInfo, pSupporter->pMeterDataInfo);
+    queryOnMultiDataCache(pQInfo, pSupporter->pMeterDataInfo);
     if (pQInfo->code != TSDB_CODE_SUCCESS) {
       return;
     }
 
-    pSupporter->pMeterDataInfo = queryOnMultiDataFiles(pQInfo, pSupporter->pMeterDataInfo);
+    queryOnMultiDataFiles(pQInfo, pSupporter->pMeterDataInfo);
   }
 }
 

From d2b71b378c0320d560cbddae8e379d15378f45bd Mon Sep 17 00:00:00 2001
From: xieyinglin <xieyinglin1111@163.com>
Date: Sat, 18 Jan 2020 19:01:51 +0800
Subject: [PATCH 26/35] add importSampleData link

---
 documentation/webdocs/markdowndocs/administrator-ch.md | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/documentation/webdocs/markdowndocs/administrator-ch.md b/documentation/webdocs/markdowndocs/administrator-ch.md
index 17acbacfcf..35beb610f2 100644
--- a/documentation/webdocs/markdowndocs/administrator-ch.md
+++ b/documentation/webdocs/markdowndocs/administrator-ch.md
@@ -337,7 +337,8 @@ TDengine也支持在shell对已存在的表从CSV文件中进行数据导入。
 insert into tb1 file a.csv b.csv tb2 c.csv …
 import into tb1 file a.csv b.csv tb2 c.csv …
 ```
-> 注意：导入的CSV文件不能够带表头, 且表的列与CSV文件的列需要严格对应
+> 注意：导入的CSV文件不能够带表头, 且表的列与CSV文件的列需要严格对应。
+> 同样还可以使用[样例数据导入工具][1]对数据进行横向和纵向扩展导入。
 
 ## 数据导出
 
@@ -408,3 +409,6 @@ KILL STREAM <stream-id>
 TDengine启动后，会自动创建一个监测数据库`LOG`，并自动将服务器的CPU、内存、硬盘空间、带宽、请求数、磁盘读写速度、慢查询等信息定时写入该数据库。TDengine还将重要的系统操作（比如登录、创建、删除数据库等）日志以及各种错误报警信息记录下来存放在`LOG`库里。系统管理员可以通过客户端程序查看记录库中的运行负载信息，（在企业版中）还可以通过浏览器查看数据的图标可视化结果。
 
 这些监测信息的采集缺省是打开的，但可以修改配置文件里的选项`monitor`将其关闭或打开。
+
+
+[1]: https://github.com/taosdata/TDengine/tree/develop/importSampleData
\ No newline at end of file

From ffe1cbcfbf3d93812ab0867146051f09c2afab76 Mon Sep 17 00:00:00 2001
From: lihui <huili@taosdata.com>
Date: Tue, 21 Jan 2020 15:31:30 +0800
Subject: [PATCH 27/35] [#1165]

---
 src/system/detail/src/mgmtMeter.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/src/system/detail/src/mgmtMeter.c b/src/system/detail/src/mgmtMeter.c
index 76867a0d07..a2a6ed8a7d 100644
--- a/src/system/detail/src/mgmtMeter.c
+++ b/src/system/detail/src/mgmtMeter.c
@@ -1186,6 +1186,8 @@ int mgmtRetrieveMetricMeta(SConnObj *pConn, char **pStart, SMetricMetaMsg *pMetr
   int32_t *        tagLen = calloc(1, sizeof(int32_t) * pMetricMetaMsg->numOfMeters);
 
   if (result == NULL || tagLen == NULL) {
+    tfree(result);
+    tfree(tagLen);
     return -1;
   }
 

From d4d757c3d0529a2f83973c9882c0f76a8fba2d72 Mon Sep 17 00:00:00 2001
From: slguan <slguan@taosdata.com>
Date: Fri, 31 Jan 2020 11:51:52 +0800
Subject: [PATCH 28/35] TBASE-1452  #1136

---
 src/client/src/tscSql.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/src/client/src/tscSql.c b/src/client/src/tscSql.c
index 95952c0c75..48a3609138 100644
--- a/src/client/src/tscSql.c
+++ b/src/client/src/tscSql.c
@@ -64,8 +64,11 @@ TAOS *taos_connect_imp(const char *ip, const char *user, const char *pass, const
   }
 
   if (ip && ip[0]) {
+    tscMgmtIpList.numOfIps = 2;
     strcpy(tscMgmtIpList.ipstr[0], ip);
     tscMgmtIpList.ip[0] = inet_addr(ip);
+    strcpy(tscMgmtIpList.ipstr[1], ip);
+    tscMgmtIpList.ip[1] = inet_addr(ip);
   }
 
   pObj = (STscObj *)malloc(sizeof(STscObj));

From 8828c9145c65dca21e743c99b66e4ab80cc82b1e Mon Sep 17 00:00:00 2001
From: slguan <slguan@taosdata.com>
Date: Fri, 31 Jan 2020 12:12:01 +0800
Subject: [PATCH 29/35] fix some compile errors

---
 src/system/detail/inc/vnodeStatus.h | 2 +-
 src/system/detail/src/vnodeMeter.c  | 2 +-
 src/system/detail/src/vnodeStore.c  | 4 ++--
 3 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/src/system/detail/inc/vnodeStatus.h b/src/system/detail/inc/vnodeStatus.h
index 4489710460..456304370d 100644
--- a/src/system/detail/inc/vnodeStatus.h
+++ b/src/system/detail/inc/vnodeStatus.h
@@ -26,7 +26,7 @@ enum _TSDB_VG_STATUS {
   TSDB_VG_STATUS_READY = TSDB_CODE_SUCCESS,
   TSDB_VG_STATUS_IN_PROGRESS = TSDB_CODE_ACTION_IN_PROGRESS,
   TSDB_VG_STATUS_NO_DISK_PERMISSIONS = TSDB_CODE_NO_DISK_PERMISSIONS,
-  TSDB_VG_STATUS_SERVER_NO_PACE = TSDB_CODE_SERVER_NO_SPACE,
+  TSDB_VG_STATUS_SERVER_NO_PACE = TSDB_CODE_SERV_NO_DISKSPACE,
   TSDB_VG_STATUS_SERV_OUT_OF_MEMORY = TSDB_CODE_SERV_OUT_OF_MEMORY,
   TSDB_VG_STATUS_INIT_FAILED = TSDB_CODE_VG_INIT_FAILED,
   TSDB_VG_STATUS_FULL = TSDB_CODE_NO_ENOUGH_DNODES,
diff --git a/src/system/detail/src/vnodeMeter.c b/src/system/detail/src/vnodeMeter.c
index b2d87d3081..4dc6d78707 100644
--- a/src/system/detail/src/vnodeMeter.c
+++ b/src/system/detail/src/vnodeMeter.c
@@ -81,7 +81,7 @@ int vnodeCreateMeterObjFile(int vnode) {
     if (errno == EACCES) {
       return TSDB_CODE_NO_DISK_PERMISSIONS;
     } else if (errno == ENOSPC) {
-      return TSDB_CODE_SERVER_NO_SPACE;
+      return TSDB_CODE_SERV_NO_DISKSPACE;
     } else {
       return TSDB_CODE_VG_INIT_FAILED;
     }
diff --git a/src/system/detail/src/vnodeStore.c b/src/system/detail/src/vnodeStore.c
index 59d061e085..f184381d25 100644
--- a/src/system/detail/src/vnodeStore.c
+++ b/src/system/detail/src/vnodeStore.c
@@ -188,7 +188,7 @@ int vnodeCreateVnode(int vnode, SVnodeCfg *pCfg, SVPeerDesc *pDesc) {
     if (errno == EACCES) {
       return TSDB_CODE_NO_DISK_PERMISSIONS;
     } else if (errno == ENOSPC) {
-      return TSDB_CODE_SERVER_NO_SPACE;
+      return TSDB_CODE_SERV_NO_DISKSPACE;
     } else if (errno == EEXIST) {
     } else {
       return TSDB_CODE_VG_INIT_FAILED;
@@ -201,7 +201,7 @@ int vnodeCreateVnode(int vnode, SVnodeCfg *pCfg, SVPeerDesc *pDesc) {
     if (errno == EACCES) {
       return TSDB_CODE_NO_DISK_PERMISSIONS;
     } else if (errno == ENOSPC) {
-      return TSDB_CODE_SERVER_NO_SPACE;
+      return TSDB_CODE_SERV_NO_DISKSPACE;
     } else if (errno == EEXIST) {
     } else {
       return TSDB_CODE_VG_INIT_FAILED;

From c765f363cd88e30c875a72b076fdd001d61f07b1 Mon Sep 17 00:00:00 2001
From: haojun Liao <hjxilinx@users.noreply.github.com>
Date: Fri, 31 Jan 2020 23:19:13 +0800
Subject: [PATCH 30/35] Update vnodeShell.c

---
 src/system/detail/src/vnodeShell.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/system/detail/src/vnodeShell.c b/src/system/detail/src/vnodeShell.c
index 1b442be5ff..63fe24b06a 100644
--- a/src/system/detail/src/vnodeShell.c
+++ b/src/system/detail/src/vnodeShell.c
@@ -485,7 +485,7 @@ void vnodeExecuteRetrieveReq(SSchedMsg *pSched) {
 
   // write the progress information of each meter to response
   // this is required by subscriptions
-  if (pQInfo->pMeterQuerySupporter != NULL) {
+  if (pQInfo->pMeterQuerySupporter != NULL && pQInfo->pMeterQuerySupporter->pMeterSidExtInfo != NULL) {
     *((int32_t*)pMsg) = htonl(pQInfo->pMeterQuerySupporter->numOfMeters);
     pMsg += sizeof(int32_t);
     for (int32_t i = 0; i < pQInfo->pMeterQuerySupporter->numOfMeters; i++) {

From d80ec2aad82d4075238ff2e8cf464bf0cd85f1a1 Mon Sep 17 00:00:00 2001
From: hjxilinx <hjxilinx@163.com>
Date: Fri, 31 Jan 2020 23:29:39 +0800
Subject: [PATCH 31/35] fix bugs #1170.  [tbase-1492]

---
 src/client/src/tscFunctionImpl.c | 20 ++++++++++----------
 1 file changed, 10 insertions(+), 10 deletions(-)

diff --git a/src/client/src/tscFunctionImpl.c b/src/client/src/tscFunctionImpl.c
index 22875593c2..058a0e045b 100644
--- a/src/client/src/tscFunctionImpl.c
+++ b/src/client/src/tscFunctionImpl.c
@@ -3024,14 +3024,14 @@ static void diff_function(SQLFunctionCtx *pCtx) {
         if (pCtx->param[1].nType == INITIAL_VALUE_NOT_ASSIGNED) {  // initial value is not set yet
           pCtx->param[1].i64Key = pData[i];
           pCtx->param[1].nType = pCtx->inputType;
-        } else if (i == 0) {
+        } else if ((i == 0 && pCtx->order == TSQL_SO_ASC) || (i == pCtx->size - 1 && pCtx->order == TSQL_SO_DESC)) {
           *pOutput = pData[i] - pCtx->param[1].i64Key;
           *pTimestamp = pCtx->ptsList[i];
 
           pOutput += step;
           pTimestamp += step;
         } else {
-          *pOutput = pData[i] - pData[i - 1];
+          *pOutput = pData[i] - pData[i - step];
           *pTimestamp = pCtx->ptsList[i];
 
           pOutput += step;
@@ -3056,13 +3056,13 @@ static void diff_function(SQLFunctionCtx *pCtx) {
         if (pCtx->param[1].nType == INITIAL_VALUE_NOT_ASSIGNED) {  // initial value is not set yet
           pCtx->param[1].dKey = pData[i];
           pCtx->param[1].nType = pCtx->inputType;
-        } else if (i == 0) {
+        } else if ((i == 0 && pCtx->order == TSQL_SO_ASC) || (i == pCtx->size - 1 && pCtx->order == TSQL_SO_DESC)) {
           *pOutput = pData[i] - pCtx->param[1].dKey;
           *pTimestamp = pCtx->ptsList[i];
           pOutput += step;
           pTimestamp += step;
         } else {
-          *pOutput = pData[i] - pData[i - 1];
+          *pOutput = pData[i] - pData[i - step];
           *pTimestamp = pCtx->ptsList[i];
           pOutput += step;
           pTimestamp += step;
@@ -3086,13 +3086,13 @@ static void diff_function(SQLFunctionCtx *pCtx) {
         if (pCtx->param[1].nType == INITIAL_VALUE_NOT_ASSIGNED) {  // initial value is not set yet
           pCtx->param[1].dKey = pData[i];
           pCtx->param[1].nType = pCtx->inputType;
-        } else if (i == 0) {
+        } else if ((i == 0 && pCtx->order == TSQL_SO_ASC) || (i == pCtx->size - 1 && pCtx->order == TSQL_SO_DESC)) {
           *pOutput = pData[i] - pCtx->param[1].dKey;
           *pTimestamp = pCtx->ptsList[i];
           pOutput += step;
           pTimestamp += step;
         } else {
-          *pOutput = pData[i] - pData[i - 1];
+          *pOutput = pData[i] - pData[i - step];
           *pTimestamp = pCtx->ptsList[i];
           pOutput += step;
           pTimestamp += step;
@@ -3117,13 +3117,13 @@ static void diff_function(SQLFunctionCtx *pCtx) {
         if (pCtx->param[1].nType == INITIAL_VALUE_NOT_ASSIGNED) {  // initial value is not set yet
           pCtx->param[1].i64Key = pData[i];
           pCtx->param[1].nType = pCtx->inputType;
-        } else if (i == 0) {
+        } else if ((i == 0 && pCtx->order == TSQL_SO_ASC) || (i == pCtx->size - 1 && pCtx->order == TSQL_SO_DESC)) {
           *pOutput = pData[i] - pCtx->param[1].i64Key;
           *pTimestamp = pCtx->ptsList[i];
           pOutput += step;
           pTimestamp += step;
         } else {
-          *pOutput = pData[i] - pData[i - 1];
+          *pOutput = pData[i] - pData[i - step];
           *pTimestamp = pCtx->ptsList[i];
           pOutput += step;
           pTimestamp += step;
@@ -3147,13 +3147,13 @@ static void diff_function(SQLFunctionCtx *pCtx) {
         if (pCtx->param[1].nType == INITIAL_VALUE_NOT_ASSIGNED) {  // initial value is not set yet
           pCtx->param[1].i64Key = pData[i];
           pCtx->param[1].nType = pCtx->inputType;
-        } else if (i == 0) {
+        } else if ((i == 0 && pCtx->order == TSQL_SO_ASC) || (i == pCtx->size - 1 && pCtx->order == TSQL_SO_DESC)) {
           *pOutput = pData[i] - pCtx->param[1].i64Key;
           *pTimestamp = pCtx->ptsList[i];
           pOutput += step;
           pTimestamp += step;
         } else {
-          *pOutput = pData[i] - pData[i - 1];
+          *pOutput = pData[i] - pData[i - step];
           *pTimestamp = pCtx->ptsList[i];
           pOutput += step;
           pTimestamp += step;

From 8d4b992f16ee047236fb257d0d67456bfe3dbe2b Mon Sep 17 00:00:00 2001
From: slguan <slguan@taosdata.com>
Date: Sat, 1 Feb 2020 13:46:06 +0800
Subject: [PATCH 32/35] failed to connect to server while use secondIp

---
 src/client/src/tscServer.c | 2 +-
 src/client/src/tscSql.c    | 6 +++++-
 2 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/src/client/src/tscServer.c b/src/client/src/tscServer.c
index 9f512eb62b..85915f780d 100644
--- a/src/client/src/tscServer.c
+++ b/src/client/src/tscServer.c
@@ -397,7 +397,7 @@ void *tscProcessMsgFromServer(char *msg, void *ahandle, void *thandle) {
 
   SMeterMetaInfo *pMeterMetaInfo = tscGetMeterMetaInfo(pCmd, 0);
   if (msg == NULL) {
-    tscTrace("%p no response from ip:0x%x", pSql, pSql->ip);
+    tscTrace("%p no response from ip:%s", pSql, taosIpStr(pSql->ip));
 
     pSql->index++;
     pSql->thandle = NULL;
diff --git a/src/client/src/tscSql.c b/src/client/src/tscSql.c
index 48a3609138..795c9af318 100644
--- a/src/client/src/tscSql.c
+++ b/src/client/src/tscSql.c
@@ -64,11 +64,15 @@ TAOS *taos_connect_imp(const char *ip, const char *user, const char *pass, const
   }
 
   if (ip && ip[0]) {
-    tscMgmtIpList.numOfIps = 2;
+    tscMgmtIpList.numOfIps = 4;
     strcpy(tscMgmtIpList.ipstr[0], ip);
     tscMgmtIpList.ip[0] = inet_addr(ip);
     strcpy(tscMgmtIpList.ipstr[1], ip);
     tscMgmtIpList.ip[1] = inet_addr(ip);
+    strcpy(tscMgmtIpList.ipstr[2], tsMasterIp);
+    tscMgmtIpList.ip[2] = inet_addr(tsMasterIp);
+    strcpy(tscMgmtIpList.ipstr[3], tsSecondIp);
+    tscMgmtIpList.ip[3] = inet_addr(tsSecondIp);
   }
 
   pObj = (STscObj *)malloc(sizeof(STscObj));

From 2735c956248038f9ddce02067dc981f781b481e4 Mon Sep 17 00:00:00 2001
From: hjxilinx <hjxilinx@163.com>
Date: Sat, 1 Feb 2020 23:13:54 +0800
Subject: [PATCH 33/35] fix a memory leak for null value projection in tags.

---
 src/system/detail/src/vnodeQueryImpl.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/src/system/detail/src/vnodeQueryImpl.c b/src/system/detail/src/vnodeQueryImpl.c
index 0daa0936e9..760ca94bf9 100644
--- a/src/system/detail/src/vnodeQueryImpl.c
+++ b/src/system/detail/src/vnodeQueryImpl.c
@@ -4525,10 +4525,11 @@ static void doSetTagValueInParam(tTagSchema *pTagSchema, int32_t tagColIdx, SMet
   SSchema *pCol = &pTagSchema->pSchema[tagColIdx];
 
   tVariantDestroy(param);
-  tVariantCreateFromBinary(param, pStr, pCol->bytes, pCol->type);
 
   if (isNull(pStr, pCol->type)) {
     param->nType = TSDB_DATA_TYPE_NULL;
+  } else {
+    tVariantCreateFromBinary(param, pStr, pCol->bytes, pCol->type);
   }
 }
 

From c87c43051501dac6f719ca71e19140449574d41d Mon Sep 17 00:00:00 2001
From: hjxilinx <hjxilinx@163.com>
Date: Sun, 2 Feb 2020 13:51:49 +0800
Subject: [PATCH 34/35] fix a memory leak.

---
 src/system/detail/src/vnodeQueryImpl.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/src/system/detail/src/vnodeQueryImpl.c b/src/system/detail/src/vnodeQueryImpl.c
index 760ca94bf9..c1653b5dad 100644
--- a/src/system/detail/src/vnodeQueryImpl.c
+++ b/src/system/detail/src/vnodeQueryImpl.c
@@ -5994,10 +5994,13 @@ int32_t getDataBlocksForMeters(SMeterQuerySupportObj *pSupporter, SQuery *pQuery
     size_t  bufferSize = size + sizeof(TSCKSUM);
     
     pMeterDataInfo[j]->numOfBlocks = compInfo.numOfBlocks;
-    pMeterDataInfo[j]->pBlock = calloc(1, bufferSize);
-    if (pMeterDataInfo[j]->pBlock == NULL) {
+    char* p = realloc(pMeterDataInfo[j]->pBlock, bufferSize);
+    if (p == NULL) {
       clearAllMeterDataBlockInfo(pMeterDataInfo, 0, numOfMeters);
       return TSDB_CODE_SERV_OUT_OF_MEMORY;
+    } else {
+      memset(p, 0, bufferSize);
+      pMeterDataInfo[j]->pBlock = (SCompBlock*) p;
     }
   
     read(pVnodeFileInfo->headerFd, pMeterDataInfo[j]->pBlock, bufferSize);

From 5031ac214449b73ecd3fe9d8d200a70a85c1be1f Mon Sep 17 00:00:00 2001
From: hjxilinx <hjxilinx@163.com>
Date: Sun, 2 Feb 2020 22:46:50 +0800
Subject: [PATCH 35/35] fix a memory leak for super table join.

---
 src/system/detail/src/vnodeQueryProcess.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/src/system/detail/src/vnodeQueryProcess.c b/src/system/detail/src/vnodeQueryProcess.c
index 1783a1a0b4..8ad2c3f309 100644
--- a/src/system/detail/src/vnodeQueryProcess.c
+++ b/src/system/detail/src/vnodeQueryProcess.c
@@ -573,10 +573,10 @@ static void vnodeMultiMeterMultiOutputProcessor(SQInfo *pQInfo) {
   tSidSet *pSids = pSupporter->pSidSet;
 
   SMeterObj *pOneMeter = getMeterObj(pSupporter->pMeterObj, pMeterSidExtInfo[0]->sid);
-
-  resetCtxOutputBuf(pRuntimeEnv);
-
+  
   if (isPointInterpoQuery(pQuery)) {
+    resetCtxOutputBuf(pRuntimeEnv);
+  
     assert(pQuery->limit.offset == 0 && pQuery->limit.limit != 0);
 
     while (pSupporter->subgroupIdx < pSids->numOfSubSet) {
@@ -663,7 +663,9 @@ static void vnodeMultiMeterMultiOutputProcessor(SQInfo *pQInfo) {
     if (pSupporter->meterIdx >= pSids->numOfSids) {
       return;
     }
-
+  
+    resetCtxOutputBuf(pRuntimeEnv);
+  
     for (int32_t i = 0; i < pRuntimeEnv->usedIndex; ++i) {
       SOutputRes *pOneRes = &pRuntimeEnv->pResult[i];
       clearGroupResultBuf(pOneRes, pQuery->numOfOutputCols);