diff --git a/.gitignore b/.gitignore
index ba8611030b..f2c1cb75b3 100644
--- a/.gitignore
+++ b/.gitignore
@@ -12,6 +12,7 @@ rpms/
 mac/
 *.pyc
 *.tmp
+*.swp
 src/connector/nodejs/node_modules/
 src/connector/nodejs/out/
 tests/test/
diff --git a/src/client/inc/tsclient.h b/src/client/inc/tsclient.h
index 9cb43a9f36..054b2894c5 100644
--- a/src/client/inc/tsclient.h
+++ b/src/client/inc/tsclient.h
@@ -357,7 +357,6 @@ typedef struct SSqlObj {
   char              freed : 4;
   char              listed : 4;
   tsem_t            rspSem;
-  tsem_t            emptyRspSem;
   SSqlCmd           cmd;
   SSqlRes           res;
   uint8_t           numOfSubs;
@@ -409,7 +408,7 @@ int  tscProcessSql(SSqlObj *pSql);
 int  tscRenewMeterMeta(SSqlObj *pSql, char *tableId);
 void tscQueueAsyncRes(SSqlObj *pSql);
 
-void tscQueueAsyncError(void(*fp), void *param);
+void tscQueueAsyncError(void(*fp), void *param, int32_t code);
 
 int tscProcessLocalCmd(SSqlObj *pSql);
 int tscCfgDynamicOptions(char *msg);
@@ -450,7 +449,7 @@ void tscFreeSqlObj(SSqlObj *pObj);
 
 void tscCloseTscObj(STscObj *pObj);
 
-void doAsyncQuery(STscObj* pObj, SSqlObj* pSql, void (*fp)(), void* param, const char* sqlstr, int32_t sqlLen);
+void doAsyncQuery(STscObj* pObj, SSqlObj* pSql, void (*fp)(), void* param, const char* sqlstr, size_t sqlLen);
 
 void tscProcessMultiVnodesInsert(SSqlObj *pSql);
 void tscProcessMultiVnodesInsertFromFile(SSqlObj *pSql);
diff --git a/src/client/src/tscAsync.c b/src/client/src/tscAsync.c
index c1738e6801..10878ee37f 100644
--- a/src/client/src/tscAsync.c
+++ b/src/client/src/tscAsync.c
@@ -40,7 +40,7 @@ static void tscProcessAsyncRetrieveImpl(void *param, TAOS_RES *tres, int numOfRo
 static void tscAsyncFetchRowsProxy(void *param, TAOS_RES *tres, int numOfRows);
 static void tscAsyncFetchSingleRowProxy(void *param, TAOS_RES *tres, int numOfRows);
 
-void doAsyncQuery(STscObj* pObj, SSqlObj* pSql, void (*fp)(), void* param, const char* sqlstr, int32_t sqlLen) {
+void doAsyncQuery(STscObj* pObj, SSqlObj* pSql, void (*fp)(), void* param, const char* sqlstr, size_t sqlLen) {
   SSqlCmd *pCmd = &pSql->cmd;
   SSqlRes *pRes = &pSql->res;
   
@@ -51,17 +51,15 @@ void doAsyncQuery(STscObj* pObj, SSqlObj* pSql, void (*fp)(), void* param, const
   
   if (TSDB_CODE_SUCCESS != tscAllocPayload(pCmd, TSDB_DEFAULT_PAYLOAD_SIZE)) {
     tscError("failed to malloc payload");
-    tfree(pSql);
-    tscQueueAsyncError(fp, param);
+    tscQueueAsyncError(fp, param, TSDB_CODE_CLI_OUT_OF_MEMORY);
     return;
   }
   
-  pSql->sqlstr = malloc(sqlLen + 1);
+  pSql->sqlstr = realloc(pSql->sqlstr, sqlLen + 1);
   if (pSql->sqlstr == NULL) {
     tscError("%p failed to malloc sql string buffer", pSql);
-    tscQueueAsyncError(fp, param);
+    tscQueueAsyncError(fp, param, TSDB_CODE_CLI_OUT_OF_MEMORY);
     free(pCmd->payload);
-    free(pSql);
     return;
   }
   
@@ -75,7 +73,7 @@ void doAsyncQuery(STscObj* pObj, SSqlObj* pSql, void (*fp)(), void* param, const
   if (code == TSDB_CODE_ACTION_IN_PROGRESS) return;
   
   if (code != TSDB_CODE_SUCCESS) {
-    pSql->res.code = (uint8_t)code;
+    pSql->res.code = code;
     tscQueueAsyncRes(pSql);
     return;
   }
@@ -88,15 +86,16 @@ void taos_query_a(TAOS *taos, const char *sqlstr, __async_cb_func_t fp, void *pa
   STscObj *pObj = (STscObj *)taos;
   if (pObj == NULL || pObj->signature != pObj) {
     tscError("bug!!! pObj:%p", pObj);
-    globalCode = TSDB_CODE_DISCONNECTED;
-    tscQueueAsyncError(fp, param);
+    terrno = TSDB_CODE_DISCONNECTED;
+    tscQueueAsyncError(fp, param, TSDB_CODE_DISCONNECTED);
     return;
   }
   
   int32_t sqlLen = strlen(sqlstr);
   if (sqlLen > tsMaxSQLStringLen) {
     tscError("sql string too long");
-    tscQueueAsyncError(fp, param);
+    terrno = TSDB_CODE_INVALID_SQL;
+    tscQueueAsyncError(fp, param, TSDB_CODE_INVALID_SQL);
     return;
   }
   
@@ -105,7 +104,8 @@ void taos_query_a(TAOS *taos, const char *sqlstr, __async_cb_func_t fp, void *pa
   SSqlObj *pSql = (SSqlObj *)calloc(1, sizeof(SSqlObj));
   if (pSql == NULL) {
     tscError("failed to malloc sqlObj");
-    tscQueueAsyncError(fp, param);
+    terrno = TSDB_CODE_CLI_OUT_OF_MEMORY;
+    tscQueueAsyncError(fp, param, TSDB_CODE_CLI_OUT_OF_MEMORY);
     return;
   }
   
@@ -170,7 +170,7 @@ static void tscProcessAsyncRetrieveImpl(void *param, TAOS_RES *tres, int numOfRo
       pRes->code = numOfRows;
     }
 
-    tscQueueAsyncError(pSql->fetchFp, param);
+    tscQueueAsyncError(pSql->fetchFp, param, pRes->code);
     return;
   }
 
@@ -200,8 +200,8 @@ void taos_fetch_rows_a(TAOS_RES *taosa, void (*fp)(void *, TAOS_RES *, int), voi
   SSqlObj *pSql = (SSqlObj *)taosa;
   if (pSql == NULL || pSql->signature != pSql) {
     tscError("sql object is NULL");
-    globalCode = TSDB_CODE_DISCONNECTED;
-    tscQueueAsyncError(fp, param);
+//    globalCode = TSDB_CODE_DISCONNECTED;
+    tscQueueAsyncError(fp, param, TSDB_CODE_DISCONNECTED);
     return;
   }
 
@@ -210,7 +210,7 @@ void taos_fetch_rows_a(TAOS_RES *taosa, void (*fp)(void *, TAOS_RES *, int), voi
 
   if (pRes->qhandle == 0) {
     tscError("qhandle is NULL");
-    tscQueueAsyncError(fp, param);
+    tscQueueAsyncError(fp, param, TSDB_CODE_INVALID_QHANDLE);
     return;
   }
 
@@ -232,8 +232,8 @@ void taos_fetch_row_a(TAOS_RES *taosa, void (*fp)(void *, TAOS_RES *, TAOS_ROW),
   SSqlObj *pSql = (SSqlObj *)taosa;
   if (pSql == NULL || pSql->signature != pSql) {
     tscError("sql object is NULL");
-    globalCode = TSDB_CODE_DISCONNECTED;
-    tscQueueAsyncError(fp, param);
+//    globalCode = TSDB_CODE_DISCONNECTED;
+    tscQueueAsyncError(fp, param, TSDB_CODE_DISCONNECTED);
     return;
   }
 
@@ -242,7 +242,7 @@ void taos_fetch_row_a(TAOS_RES *taosa, void (*fp)(void *, TAOS_RES *, TAOS_ROW),
 
   if (pRes->qhandle == 0) {
     tscError("qhandle is NULL");
-    tscQueueAsyncError(fp, param);
+    tscQueueAsyncError(fp, param, TSDB_CODE_INVALID_QHANDLE);
     return;
   }
 
@@ -331,7 +331,7 @@ void tscProcessAsyncRes(SSchedMsg *pMsg) {
 
   // pCmd may be released, so cache pCmd->command
   int cmd = pCmd->command;
-  int code = pRes->code ? -pRes->code : pRes->numOfRows;
+  int code = pRes->code;// ? -pRes->code : pRes->numOfRows;
 
   // in case of async insert, restore the user specified callback function
   bool shouldFree = tscShouldFreeAsyncSqlObj(pSql);
@@ -349,18 +349,20 @@ void tscProcessAsyncRes(SSchedMsg *pMsg) {
   }
 }
 
-void tscProcessAsyncError(SSchedMsg *pMsg) {
+static void tscProcessAsyncError(SSchedMsg *pMsg) {
   void (*fp)() = pMsg->ahandle;
-
-  (*fp)(pMsg->thandle, NULL, -1);
+  (*fp)(pMsg->thandle, NULL, *(int32_t*)pMsg->msg);
 }
 
-void tscQueueAsyncError(void(*fp), void *param) {
+void tscQueueAsyncError(void(*fp), void *param, int32_t code) {
+  int32_t* c = malloc(sizeof(int32_t));
+  *c = code;
+  
   SSchedMsg schedMsg;
   schedMsg.fp = tscProcessAsyncError;
   schedMsg.ahandle = fp;
   schedMsg.thandle = param;
-  schedMsg.msg = NULL;
+  schedMsg.msg = c;
   taosScheduleTask(tscQhandle, &schedMsg);
 }
 
@@ -412,7 +414,7 @@ void tscTableMetaCallBack(void *param, TAOS_RES *res, int code) {
     if (code != 0) {
       pRes->code = code;
       tscTrace("%p failed to renew tableMeta", pSql);
-      tsem_post(&pSql->rspSem);
+//      tsem_post(&pSql->rspSem);
     } else {
       tscTrace("%p renew tableMeta successfully, command:%d, code:%d, retry:%d",
           pSql, pSql->cmd.command, pSql->res.code, pSql->retry);
@@ -424,7 +426,7 @@ void tscTableMetaCallBack(void *param, TAOS_RES *res, int code) {
       code = tscSendMsgToServer(pSql);
       if (code != 0) {
         pRes->code = code;
-        tsem_post(&pSql->rspSem);
+//        tsem_post(&pSql->rspSem);
       }
     }
 
diff --git a/src/client/src/tscPrepare.c b/src/client/src/tscPrepare.c
index 241f24a747..8b065fcf51 100644
--- a/src/client/src/tscPrepare.c
+++ b/src/client/src/tscPrepare.c
@@ -488,7 +488,6 @@ TAOS_STMT* taos_stmt_init(TAOS* taos) {
   }
 
   tsem_init(&pSql->rspSem, 0, 0);
-  tsem_init(&pSql->emptyRspSem, 0, 1);
   pSql->signature = pSql;
   pSql->pTscObj = pObj;
 
diff --git a/src/client/src/tscSQLParser.c b/src/client/src/tscSQLParser.c
index 4db33b0291..5696611387 100644
--- a/src/client/src/tscSQLParser.c
+++ b/src/client/src/tscSQLParser.c
@@ -117,7 +117,7 @@ static int32_t doCheckForCreateFromStable(SSqlObj* pSql, SSqlInfo* pInfo);
 static int32_t doCheckForStream(SSqlObj* pSql, SSqlInfo* pInfo);
 static int32_t doCheckForQuery(SSqlObj* pSql, SQuerySQL* pQuerySql, int32_t index);
 
-static int32_t tSQLBinaryExprCreateFromSqlExpr(tSQLSyntaxNode **pExpr, tSQLExpr* pAst, int32_t* num,
+static int32_t convertSyntaxTreeToExprTree(tExprNode **pExpr, tSQLExpr* pAst, int32_t* num,
     SColIndexEx** pColIndex, SSqlExprInfo* pExprInfo);
 
 /*
@@ -215,7 +215,7 @@ int32_t tscToSQLCmd(SSqlObj* pSql, struct SSqlInfo* pInfo) {
   if (pQueryInfo->numOfTables == 0) {
     pTableMetaInfo = tscAddEmptyMetaInfo(pQueryInfo);
   } else {
-    pTableMetaInfo = &pQueryInfo->pTableMetaInfo[0];
+    pTableMetaInfo = pQueryInfo->pTableMetaInfo[0];
   }
 
   pCmd->command = pInfo->type;
@@ -1208,12 +1208,12 @@ int32_t parseSelectClause(SSqlCmd* pCmd, int32_t clauseIndex, tSQLExprList* pSel
 
           SSqlBinaryExprInfo* pBinExprInfo = &pFuncExpr->binExprInfo;
           
-          tSQLSyntaxNode* pNode = NULL;
+          tExprNode* pNode = NULL;
           SColIndexEx* pColIndex = NULL;
           
-          int32_t ret = tSQLBinaryExprCreateFromSqlExpr(&pNode, pItem->pNode, &pBinExprInfo->numOfCols, &pColIndex, &pQueryInfo->exprsInfo);
+          int32_t ret = convertSyntaxTreeToExprTree(&pNode, pItem->pNode, &pBinExprInfo->numOfCols, &pColIndex, &pQueryInfo->exprsInfo);
           if (ret != TSDB_CODE_SUCCESS) {
-            tSQLBinaryExprDestroy(&pNode, NULL);
+            tExprTreeDestroy(&pNode, NULL);
             return invalidSqlErrMsg(pQueryInfo->msg, "invalid expression in select clause");
           }
           
@@ -5807,20 +5807,20 @@ int32_t doCheckForQuery(SSqlObj* pSql, SQuerySQL* pQuerySql, int32_t index) {
   return TSDB_CODE_SUCCESS;  // Does not build query message here
 }
 
-static int32_t tSQLBinaryExprCreateFromSqlExpr(tSQLSyntaxNode **pExpr, tSQLExpr* pAst, int32_t* num,
+static int32_t convertSyntaxTreeToExprTree(tExprNode **pExpr, tSQLExpr* pAst, int32_t* num,
     SColIndexEx** pColIndex, SSqlExprInfo* pExprInfo) {
-  tSQLSyntaxNode* pLeft = NULL;
-  tSQLSyntaxNode* pRight= NULL;
+  tExprNode* pLeft = NULL;
+  tExprNode* pRight= NULL;
   
   if (pAst->pLeft != NULL) {
-    int32_t ret = tSQLBinaryExprCreateFromSqlExpr(&pLeft, pAst->pLeft, num, pColIndex, pExprInfo);
+    int32_t ret = convertSyntaxTreeToExprTree(&pLeft, pAst->pLeft, num, pColIndex, pExprInfo);
     if (ret != TSDB_CODE_SUCCESS) {
       return ret;
     }
   }
   
   if (pAst->pRight != NULL) {
-    int32_t ret = tSQLBinaryExprCreateFromSqlExpr(&pRight, pAst->pRight, num, pColIndex, pExprInfo);
+    int32_t ret = convertSyntaxTreeToExprTree(&pRight, pAst->pRight, num, pColIndex, pExprInfo);
     if (ret != TSDB_CODE_SUCCESS) {
       return ret;
     }
@@ -5828,14 +5828,14 @@ static int32_t tSQLBinaryExprCreateFromSqlExpr(tSQLSyntaxNode **pExpr, tSQLExpr*
   
   if (pAst->pLeft == NULL) {
     if (pAst->nSQLOptr >= TK_TINYINT && pAst->nSQLOptr <= TK_DOUBLE) {
-      *pExpr = calloc(1, sizeof(tSQLSyntaxNode) + sizeof(tVariant));
+      *pExpr = calloc(1, sizeof(tExprNode) + sizeof(tVariant));
       (*pExpr)->nodeType = TSQL_NODE_VALUE;
-      (*pExpr)->pVal = (tVariant*) ((char*)(*pExpr) + sizeof(tSQLSyntaxNode));
+      (*pExpr)->pVal = (tVariant*) ((char*)(*pExpr) + sizeof(tExprNode));
       tVariantAssign((*pExpr)->pVal, &pAst->val);
     } else if (pAst->nSQLOptr >= TK_COUNT && pAst->nSQLOptr <= TK_AVG_IRATE) {
-      *pExpr = calloc(1, sizeof(tSQLSyntaxNode) + sizeof(SSchemaEx));
+      *pExpr = calloc(1, sizeof(tExprNode) + sizeof(SSchemaEx));
       (*pExpr)->nodeType = TSQL_NODE_COL;
-      (*pExpr)->pSchema = (SSchema*)((char*)(*pExpr) + sizeof(tSQLSyntaxNode));
+      (*pExpr)->pSchema = (SSchema*)((char*)(*pExpr) + sizeof(tExprNode));
       strncpy((*pExpr)->pSchema->name, pAst->operand.z, pAst->operand.n);
 
       // set the input column data byte and type.
@@ -5855,7 +5855,7 @@ static int32_t tSQLBinaryExprCreateFromSqlExpr(tSQLSyntaxNode **pExpr, tSQLExpr*
     
     strncpy((*pColIndex)[(*num) - 1].name, pAst->operand.z, pAst->operand.n);
   } else {
-    *pExpr = (tSQLSyntaxNode *)calloc(1, sizeof(tSQLSyntaxNode));
+    *pExpr = (tExprNode *)calloc(1, sizeof(tExprNode));
     (*pExpr)->_node.hasPK = false;
     (*pExpr)->_node.pLeft = pLeft;
     (*pExpr)->_node.pRight = pRight;
diff --git a/src/client/src/tscServer.c b/src/client/src/tscServer.c
index e57f9cc410..f651c35324 100644
--- a/src/client/src/tscServer.c
+++ b/src/client/src/tscServer.c
@@ -285,14 +285,16 @@ void tscProcessMsgFromServer(SRpcMsg *rpcMsg) {
     pRes->rspType = rpcMsg->msgType;
     pRes->rspLen  = rpcMsg->contLen;
 
-    char *tmp = (char *)realloc(pRes->pRsp, pRes->rspLen);
-    if (tmp == NULL) {
-      pRes->code = TSDB_CODE_CLI_OUT_OF_MEMORY;
-    } else {
-      pRes->pRsp = tmp;
-      if (pRes->rspLen) {
+    if (pRes->rspLen > 0) {
+      char *tmp = (char *)realloc(pRes->pRsp, pRes->rspLen);
+      if (tmp == NULL) {
+        pRes->code = TSDB_CODE_CLI_OUT_OF_MEMORY;
+      } else {
+        pRes->pRsp = tmp;
         memcpy(pRes->pRsp, rpcMsg->pCont, pRes->rspLen);
       }
+    } else {
+      pRes->pRsp = NULL;
     }
 
     // ignore the error information returned from mnode when set ignore flag in sql
@@ -327,7 +329,7 @@ void tscProcessMsgFromServer(SRpcMsg *rpcMsg) {
     void *taosres = tscKeepConn[pCmd->command] ? pSql : NULL;
     rpcMsg->code = pRes->code ? pRes->code : pRes->numOfRows;
     
-    tscTrace("%p Async SQL result:%s res:%p", pSql, tstrerror(pRes->code), taosres);
+    tscTrace("%p Async SQL result:%s res:%p", pSql, tstrerror(pRes->code), pSql);
 
     /*
      * Whether to free sqlObj or not should be decided before call the user defined function, since this SqlObj
diff --git a/src/client/src/tscSql.c b/src/client/src/tscSql.c
index bbf46a2353..f33e589c82 100644
--- a/src/client/src/tscSql.c
+++ b/src/client/src/tscSql.c
@@ -155,6 +155,10 @@ static void syncConnCallback(void *param, TAOS_RES *tres, int code) {
   STscObj *pObj = (STscObj *)param;
   assert(pObj != NULL && pObj->pSql != NULL);
   
+  if (code < 0) {
+    pObj->pSql->res.code = code;
+  }
+  
   sem_post(&pObj->pSql->rspSem);
 }
 
@@ -177,17 +181,17 @@ TAOS *taos_connect(const char *ip, const char *user, const char *pass, const cha
     sem_wait(&pSql->rspSem);
     
     if (pSql->res.code != TSDB_CODE_SUCCESS) {
+      terrno = pSql->res.code;
       taos_close(pObj);
       return NULL;
     }
     
     tscTrace("%p DB connection is opening", pObj);
-
+    
     // version compare only requires the first 3 segments of the version string
     int code = taosCheckVersion(version, taos_get_server_info(pObj), 3);
     if (code != 0) {
-      pSql->res.code = code;
-      
+      terrno = code;
       taos_close(pObj);
       return NULL;
     } else {
@@ -267,31 +271,29 @@ int taos_query_imp(STscObj *pObj, SSqlObj *pSql) {
   return pRes->code;
 }
 
-static void syncQueryCallback(void *param, TAOS_RES *tres, int code) {
-  STscObj *pObj = (STscObj *)param;
-  assert(pObj != NULL && pObj->pSql != NULL);
+static void waitForQueryRsp(void *param, TAOS_RES *tres, int code) {
+  assert(param != NULL);
+  SSqlObj *pSql = ((STscObj *)param)->pSql;
   
-  sem_post(&pObj->pSql->rspSem);
+  // valid error code is less than 0
+  if (code < 0) {
+    pSql->res.code = code;
+  }
+  
+  sem_post(&pSql->rspSem);
 }
 
 int taos_query(TAOS *taos, const char *sqlstr) {
   STscObj *pObj = (STscObj *)taos;
   if (pObj == NULL || pObj->signature != pObj) {
-    globalCode = TSDB_CODE_DISCONNECTED;
+    terrno = TSDB_CODE_DISCONNECTED;
     return TSDB_CODE_DISCONNECTED;
   }
   
-  SSqlObj *pSql = (SSqlObj *)calloc(1, sizeof(SSqlObj));
-  if (pSql == NULL) {
-    tscError("failed to malloc sqlObj");
-    return TSDB_CODE_CLI_OUT_OF_MEMORY;
-  }
+  SSqlObj* pSql = pObj->pSql;
   
-  pObj->pSql = pSql;
-  tsem_init(&pSql->rspSem, 0, 0);
-  
-  int32_t sqlLen = strlen(sqlstr);
-  doAsyncQuery(pObj, pObj->pSql, syncQueryCallback, taos, sqlstr, sqlLen);
+  size_t sqlLen = strlen(sqlstr);
+  doAsyncQuery(pObj, pObj->pSql, waitForQueryRsp, taos, sqlstr, sqlLen);
 
   // wait for the callback function to post the semaphore
   sem_wait(&pSql->rspSem);
@@ -649,12 +651,12 @@ static void **tscBuildResFromSubqueries(SSqlObj *pSql) {
   return pRes->tsrow;
 }
 
-static void asyncFetchCallback(void *param, TAOS_RES *tres, int numOfRows) {
+static void waitForRetrieveRsp(void *param, TAOS_RES *tres, int numOfRows) {
   SSqlObj* pSql = (SSqlObj*) tres;
+  
   if (numOfRows < 0) { // set the error code
     pSql->res.code = -numOfRows;
   }
-  
   sem_post(&pSql->rspSem);
 }
 
@@ -677,7 +679,7 @@ TAOS_ROW taos_fetch_row(TAOS_RES *res) {
   // current data are exhausted, fetch more data
   if (pRes->data == NULL || (pRes->data != NULL && pRes->row >= pRes->numOfRows && pRes->completed != true &&
       (pCmd->command == TSDB_SQL_RETRIEVE || pCmd->command == TSDB_SQL_RETRIEVE_METRIC || pCmd->command == TSDB_SQL_FETCH))) {
-    taos_fetch_rows_a(res, asyncFetchCallback, pSql->pTscObj);
+    taos_fetch_rows_a(res, waitForRetrieveRsp, pSql->pTscObj);
     
     sem_wait(&pSql->rspSem);
   }
@@ -754,20 +756,18 @@ void taos_free_result_imp(TAOS_RES *res, int keepCmd) {
   if (pRes == NULL || pRes->qhandle == 0) {
     /* Query rsp is not received from vnode, so the qhandle is NULL */
     tscTrace("%p qhandle is null, abort free, fp:%p", pSql, pSql->fp);
-    if (pSql->fp != NULL) {
-      STscObj* pObj = pSql->pTscObj;
-  
-      if (pSql == pObj->pSql) {
-        pObj->pSql = NULL;
-        tscFreeSqlObj(pSql);
-      }
-      
+    
+    if (tscShouldFreeAsyncSqlObj(pSql)) {
+      tscFreeSqlObj(pSql);
       tscTrace("%p Async SqlObj is freed by app", pSql);
-    } else if (keepCmd) {
-      tscFreeSqlResult(pSql);
     } else {
-      tscFreeSqlObjPartial(pSql);
+      if (keepCmd) {
+        tscFreeSqlResult(pSql);
+      } else {
+        tscFreeSqlObjPartial(pSql);
+      }
     }
+    
     return;
   }
 
@@ -793,7 +793,7 @@ void taos_free_result_imp(TAOS_RES *res, int keepCmd) {
    *         be executed, and the retry efforts may result in double free the resources, e.g.,SRetrieveSupport
    */
   if (pRes->code != TSDB_CODE_QUERY_CANCELLED &&
-      ((pRes->numOfRows > 0 && pCmd->command < TSDB_SQL_LOCAL) ||
+      ((pRes->numOfRows > 0 && pCmd->command < TSDB_SQL_LOCAL && pRes->completed == false) ||
        (pRes->code == TSDB_CODE_SUCCESS && pRes->numOfRows == 0 && pCmd->command == TSDB_SQL_SELECT &&
         pSql->pStream == NULL && pTableMetaInfo->pTableMeta != NULL))) {
     pCmd->command = (pCmd->command > TSDB_SQL_MGMT) ? TSDB_SQL_RETRIEVE : TSDB_SQL_FETCH;
@@ -836,39 +836,37 @@ void taos_free_result_imp(TAOS_RES *res, int keepCmd) {
     }
   } else {
     // if no free resource msg is sent to vnode, we free this object immediately.
-
-    if (pSql->fp) {
+    bool free = tscShouldFreeAsyncSqlObj(pSql);
+    if (free) {
       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);
+      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 by app", pSql);
+      }
     }
   }
 }
 
 void taos_free_result(TAOS_RES *res) { taos_free_result_imp(res, 0); }
 
+// todo should not be used in async query
 int taos_errno(TAOS *taos) {
   STscObj *pObj = (STscObj *)taos;
-  int      code;
 
-  if (pObj == NULL || pObj->signature != pObj) return globalCode;
+  if (pObj == NULL || pObj->signature != pObj) {
+    return terrno;
+  }
 
-  if ((int8_t)(pObj->pSql->res.code) == -1)
-    code = TSDB_CODE_OTHERS;
-  else
-    code = pObj->pSql->res.code;
-
-  return code;
+  return pObj->pSql->res.code;
 }
 
-//static bool validErrorCode(int32_t code) { return code >= TSDB_CODE_SUCCESS && code < TSDB_CODE_MAX_ERROR_CODE; }
-
 /*
  * In case of invalid sql error, additional information is attached to explain
  * why the sql is invalid
@@ -888,13 +886,15 @@ static bool hasAdditionalErrorInfo(int32_t code, SSqlCmd *pCmd) {
   return z != NULL;
 }
 
+// todo should not be used in async model
 char *taos_errstr(TAOS *taos) {
   STscObj *pObj = (STscObj *)taos;
 
   if (pObj == NULL || pObj->signature != pObj)
-    return (char*)tstrerror(globalCode);
+    return (char*)tstrerror(terrno);
 
-  SSqlObj *pSql = pObj->pSql;
+  SSqlObj* pSql = pObj->pSql;
+  
   if (hasAdditionalErrorInfo(pSql->res.code, &pSql->cmd)) {
     return pSql->cmd.payload;
   } else {
diff --git a/src/client/src/tscSub.c b/src/client/src/tscSub.c
index 616bcbba50..9d172d4ea5 100644
--- a/src/client/src/tscSub.c
+++ b/src/client/src/tscSub.c
@@ -124,7 +124,6 @@ static SSub* tscCreateSubscription(STscObj* pObj, const char* topic, const char*
   pSql->sqlstr = sqlstr;
 
   tsem_init(&pSql->rspSem, 0, 0);
-  tsem_init(&pSql->emptyRspSem, 0, 1);
 
   SSqlRes *pRes = &pSql->res;
   pRes->numOfRows = 1;
diff --git a/src/client/src/tscSubquery.c b/src/client/src/tscSubquery.c
index b0c7b68ab4..ca6ca369e4 100644
--- a/src/client/src/tscSubquery.c
+++ b/src/client/src/tscSubquery.c
@@ -392,10 +392,10 @@ void freeSubqueryObj(SSqlObj* pSql) {
 static void doQuitSubquery(SSqlObj* pParentSql) {
   freeSubqueryObj(pParentSql);
 
-  tsem_wait(&pParentSql->emptyRspSem);
-  tsem_wait(&pParentSql->emptyRspSem);
+//  tsem_wait(&pParentSql->emptyRspSem);
+//  tsem_wait(&pParentSql->emptyRspSem);
 
-  tsem_post(&pParentSql->rspSem);
+//  tsem_post(&pParentSql->rspSem);
 }
 
 static void quitAllSubquery(SSqlObj* pSqlObj, SJoinSubquerySupporter* pSupporter) {
@@ -567,7 +567,7 @@ static void joinRetrieveCallback(void* param, TAOS_RES* tres, int numOfRows) {
         freeSubqueryObj(pParentSql);
       }
 
-      tsem_post(&pParentSql->rspSem);
+//      tsem_post(&pParentSql->rspSem);
     } else {
       tscTrace("%p sub:%p completed, completed:%d, total:%d", pParentSql, tres, finished, numOfTotal);
     }
@@ -662,7 +662,7 @@ void tscFetchDatablockFromSubquery(SSqlObj* pSql) {
   }
 
   // wait for all subquery completed
-  tsem_wait(&pSql->rspSem);
+//  tsem_wait(&pSql->rspSem);
   
   // update the records for each subquery
   for(int32_t i = 0; i < pSql->numOfSubs; ++i) {
@@ -797,10 +797,7 @@ void tscJoinQueryCallback(void* param, TAOS_RES* tres, int code) {
           tscProcessSql(pSql);
         } else {  // first retrieve from vnode during the secondary stage sub-query
           if (pParentSql->fp == NULL) {
-            tsem_wait(&pParentSql->emptyRspSem);
-            tsem_wait(&pParentSql->emptyRspSem);
-
-            tsem_post(&pParentSql->rspSem);
+//            tsem_post(&pParentSql->rspSem);
           } else {
             // set the command flag must be after the semaphore been correctly set.
             //    pPObj->cmd.command = TSDB_SQL_RETRIEVE_METRIC;
@@ -954,10 +951,7 @@ int32_t tscHandleMasterJoinQuery(SSqlObj* pSql) {
     }
   }
   
-  tsem_post(&pSql->emptyRspSem);
-  tsem_wait(&pSql->rspSem);
-  
-  tsem_post(&pSql->emptyRspSem);
+//  tsem_wait(&pSql->rspSem);
   
   if (pSql->numOfSubs <= 0) {
     pSql->cmd.command = TSDB_SQL_RETRIEVE_EMPTY_RESULT;
diff --git a/src/client/src/tscSystem.c b/src/client/src/tscSystem.c
index 7a585bfa68..ead8c09dec 100644
--- a/src/client/src/tscSystem.c
+++ b/src/client/src/tscSystem.c
@@ -40,15 +40,10 @@ void *  tscQhandle;
 void *  tscCheckDiskUsageTmr;
 int     tsInsertHeadSize;
 
-extern int            tscEmbedded;
-int                   tscNumOfThreads;
-static pthread_once_t tscinit = PTHREAD_ONCE_INIT;
-static pthread_mutex_t tscMutex;
+int tscNumOfThreads;
 
-extern int  tsTscEnableRecordSql;
-extern int  tsNumOfLogLines;
+static pthread_once_t tscinit = PTHREAD_ONCE_INIT;
 void taosInitNote(int numOfNoteLines, int maxNotes, char* lable);
-void deltaToUtcInitOnce();
 
 void tscCheckDiskUsage(void *para, void *unused) {
   taosGetDisk();
@@ -60,7 +55,6 @@ int32_t tscInitRpc(const char *user, const char *secret) {
   char secretEncrypt[32] = {0};
   taosEncryptPass((uint8_t *)secret, strlen(secret), secretEncrypt);
 
-  pthread_mutex_lock(&tscMutex);
   if (pVnodeConn == NULL) {
     memset(&rpcInit, 0, sizeof(rpcInit));
     rpcInit.localIp = tsLocalIp;
@@ -78,7 +72,6 @@ int32_t tscInitRpc(const char *user, const char *secret) {
     pVnodeConn = rpcOpen(&rpcInit);
     if (pVnodeConn == NULL) {
       tscError("failed to init connection to vnode");
-      pthread_mutex_unlock(&tscMutex);
       return -1;
     }
   }
@@ -100,12 +93,10 @@ int32_t tscInitRpc(const char *user, const char *secret) {
     pTscMgmtConn = rpcOpen(&rpcInit);
     if (pTscMgmtConn == NULL) {
       tscError("failed to init connection to mgmt");
-      pthread_mutex_unlock(&tscMutex);
       return -1;
     }
   }
 
-  pthread_mutex_unlock(&tscMutex);
   return 0;
 }
 
@@ -113,7 +104,7 @@ void taos_init_imp() {
   char        temp[128];
   struct stat dirstat;
 
-  pthread_mutex_init(&tscMutex, NULL);
+  errno = TSDB_CODE_SUCCESS;
   srand(taosGetTimestampSec());
   deltaToUtcInitOnce();
 
diff --git a/src/client/src/tscUtil.c b/src/client/src/tscUtil.c
index ec6881db3f..5c7d8789ea 100644
--- a/src/client/src/tscUtil.c
+++ b/src/client/src/tscUtil.c
@@ -469,7 +469,7 @@ void tscFreeSqlObjPartial(SSqlObj* pSql) {
   pSql->freed = 0;
   tscFreeSqlCmdData(pCmd);
   
-  tscTrace("%p free sqlObj partial completed", pSql);
+  tscTrace("%p partially free sqlObj completed", pSql);
 }
 
 void tscFreeSqlObj(SSqlObj* pSql) {
@@ -487,8 +487,6 @@ void tscFreeSqlObj(SSqlObj* pSql) {
   tfree(pCmd->payload);
 
   pCmd->allocSize = 0;
-
-  tsem_destroy(&pSql->rspSem);
   free(pSql);
 }
 
@@ -820,7 +818,9 @@ void tscCloseTscObj(STscObj* pObj) {
   taosTmrStopA(&(pObj->pTimer));
   tscFreeSqlObj(pSql);
 
+  sem_destroy(&pSql->rspSem);
   pthread_mutex_destroy(&pObj->mutex);
+  
   tscTrace("%p DB connection is closed", pObj);
   tfree(pObj);
 }
@@ -842,10 +842,9 @@ int tscAllocPayload(SSqlCmd* pCmd, int size) {
   if (pCmd->payload == NULL) {
     assert(pCmd->allocSize == 0);
 
-    pCmd->payload = (char*)malloc(size);
+    pCmd->payload = (char*)calloc(1, size);
     if (pCmd->payload == NULL) return TSDB_CODE_CLI_OUT_OF_MEMORY;
     pCmd->allocSize = size;
-    memset(pCmd->payload, 0, pCmd->allocSize);
   } else {
     if (pCmd->allocSize < size) {
       char* b = realloc(pCmd->payload, size);
@@ -853,6 +852,8 @@ int tscAllocPayload(SSqlCmd* pCmd, int size) {
       pCmd->payload = b;
       pCmd->allocSize = size;
     }
+    
+    memset(pCmd->payload, 0, pCmd->payloadLen);
   }
 
   //memset(pCmd->payload, 0, pCmd->allocSize);
@@ -1105,7 +1106,7 @@ void tscClearFieldInfo(SFieldInfo* pFieldInfo) {
   
   for(int32_t i = 0; i < pFieldInfo->numOfOutputCols; ++i) {
     if (pFieldInfo->pExpr[i] != NULL) {
-      tSQLBinaryExprDestroy(&pFieldInfo->pExpr[i]->binExprInfo.pBinExpr, NULL);
+      tExprTreeDestroy(&pFieldInfo->pExpr[i]->binExprInfo.pBinExpr, NULL);
       tfree(pFieldInfo->pExpr[i]->binExprInfo.pReqColumns);
       tfree(pFieldInfo->pExpr[i]);
     }
@@ -1742,7 +1743,7 @@ bool tscShouldFreeAsyncSqlObj(SSqlObj* pSql) {
   }
 
   STscObj* pTscObj = pSql->pTscObj;
-  if (pSql->pStream != NULL || pTscObj->pHb == pSql) {
+  if (pSql->pStream != NULL || pTscObj->pHb == pSql || pTscObj->pSql == pSql) {
     return false;
   }
 
@@ -1929,7 +1930,6 @@ STableMetaInfo* tscAddMeterMetaInfo(SQueryInfo* pQueryInfo, const char* name, ST
   }
 
   pTableMetaInfo->pTableMeta = pTableMeta;
-//  pTableMetaInfo->pMetricMeta = pMetricMeta;
   pTableMetaInfo->numOfTags = numOfTags;
 
   if (tags != NULL) {
@@ -1963,7 +1963,7 @@ void doRemoveMeterMetaInfo(SQueryInfo* pQueryInfo, int32_t index, bool removeFro
 }
 
 void tscRemoveAllMeterMetaInfo(SQueryInfo* pQueryInfo, const char* address, bool removeFromCache) {
-  tscTrace("%p deref the metric/meter meta in cache, numOfTables:%d", address, pQueryInfo->numOfTables);
+  tscTrace("%p deref the table meta in cache, numOfTables:%d", address, pQueryInfo->numOfTables);
 
   int32_t index = pQueryInfo->numOfTables;
   while (index >= 0) {
diff --git a/src/dnode/src/dnodeRead.c b/src/dnode/src/dnodeRead.c
index 1c3e3a8638..0a1f015912 100644
--- a/src/dnode/src/dnodeRead.c
+++ b/src/dnode/src/dnodeRead.c
@@ -286,6 +286,7 @@ static void dnodeProcessRetrieveMsg(void *pVnode, SReadMsg *pMsg) {
       dnodeContinueExecuteQuery(pVnode, pQInfo, pMsg);
     } else {  // no further execution invoked, release the ref to vnode
       dnodeProcessReadResult(pVnode, pMsg);
+      dnodeReleaseVnode(pVnode);
     }
   }
   
diff --git a/src/os/linux/src/tlinux.c b/src/os/linux/src/tlinux.c
index bce4a8f13d..780e2903a0 100644
--- a/src/os/linux/src/tlinux.c
+++ b/src/os/linux/src/tlinux.c
@@ -236,7 +236,7 @@ void *taosProcessAlarmSignal(void *tharg) {
   void (*callback)(int) = tharg;
 
   timer_t         timerId;
-  struct sigevent sevent;
+  struct sigevent sevent = {0};
 
   #ifdef _ALPINE
     sevent.sigev_notify = SIGEV_THREAD;
diff --git a/src/query/inc/qast.h b/src/query/inc/qast.h
index 51580445d5..616a2a46af 100644
--- a/src/query/inc/qast.h
+++ b/src/query/inc/qast.h
@@ -16,6 +16,7 @@
 #ifndef TDENGINE_TAST_H
 #define TDENGINE_TAST_H
 
+#include <tbuffer.h>
 #ifdef __cplusplus
 extern "C" {
 #endif
@@ -27,14 +28,14 @@ extern "C" {
 #include "taosdef.h"
 #include "tvariant.h"
 
-struct tSQLSyntaxNode;
+struct tExprNode;
 struct SSchema;
 struct tSkipList;
 struct tSkipListNode;
 
 enum {
-  TSQL_NODE_EXPR = 0x1,
-  TSQL_NODE_COL = 0x2,
+  TSQL_NODE_EXPR  = 0x1,
+  TSQL_NODE_COL   = 0x2,
   TSQL_NODE_VALUE = 0x4,
 };
 
@@ -60,44 +61,41 @@ typedef struct SBinaryFilterSupp {
   void *                 pExtInfo;
 } SBinaryFilterSupp;
 
-typedef struct tSQLSyntaxNode {
+typedef struct tExprNode {
   uint8_t nodeType;
   union {
     struct {
-      uint8_t optr;  // filter operator
-      uint8_t hasPK; // 0: do not contain primary filter, 1: contain
-      void *  info;  // support filter operation on this expression only available for leaf node
+      uint8_t optr;             // filter operator
+      uint8_t hasPK;            // 0: do not contain primary filter, 1: contain
+      void *  info;             // support filter operation on this expression only available for leaf node
       
-      struct tSQLSyntaxNode *pLeft;  // left child pointer
-      struct tSQLSyntaxNode *pRight; // right child pointer
+      struct tExprNode *pLeft;  // left child pointer
+      struct tExprNode *pRight; // right child pointer
     } _node;
     struct SSchema *pSchema;
     tVariant *      pVal;
   };
-} tSQLSyntaxNode;
+} tExprNode;
 
+void tSQLBinaryExprFromString(tExprNode **pExpr, SSchema *pSchema, int32_t numOfCols, char *src, int32_t len);
 
-typedef struct tQueryResultset {
-  void ** pRes;
-  int64_t num;
-} tQueryResultset;
+void tSQLBinaryExprToString(tExprNode *pExpr, char *dst, int32_t *len);
 
-void tSQLBinaryExprFromString(tSQLSyntaxNode **pExpr, SSchema *pSchema, int32_t numOfCols, char *src, int32_t len);
+void tExprTreeDestroy(tExprNode **pExprs, void (*fp)(void*));
 
-void tSQLBinaryExprToString(tSQLSyntaxNode *pExpr, char *dst, int32_t *len);
+void tSQLBinaryExprTraverse(tExprNode *pExpr, SSkipList *pSkipList, SArray *result, SBinaryFilterSupp *param);
 
-void tSQLBinaryExprDestroy(tSQLSyntaxNode **pExprs, void (*fp)(void*));
-
-void tSQLBinaryExprTraverse(tSQLSyntaxNode *pExpr, SSkipList *pSkipList, SArray *result, SBinaryFilterSupp *param);
-
-void tSQLBinaryExprCalcTraverse(tSQLSyntaxNode *pExprs, int32_t numOfRows, char *pOutput, void *param, int32_t order,
+void tSQLBinaryExprCalcTraverse(tExprNode *pExprs, int32_t numOfRows, char *pOutput, void *param, int32_t order,
                                 char *(*cb)(void *, char *, int32_t));
 
-void tSQLBinaryExprTrv(tSQLSyntaxNode *pExprs, int32_t *val, int16_t *ids);
-void tQueryResultClean(tQueryResultset *pRes);
+void tSQLBinaryExprTrv(tExprNode *pExprs, int32_t *val, int16_t *ids);
 
 uint8_t getBinaryExprOptr(SSQLToken *pToken);
 
+SBuffer exprTreeToBinary(tExprNode* pExprTree);
+
+tExprNode* exprTreeFromBinary(const void* pBuf, size_t size);
+
 #ifdef __cplusplus
 }
 #endif
diff --git a/src/query/inc/qsqlparser.h b/src/query/inc/qsqlparser.h
index 951caa8073..b1799b6902 100644
--- a/src/query/inc/qsqlparser.h
+++ b/src/query/inc/qsqlparser.h
@@ -13,8 +13,8 @@
  * along with this program. If not, see <http://www.gnu.org/licenses/>.
  */
 
-#ifndef TDENGINE_QASTDEF_H
-#define TDENGINE_QASTDEF_H
+#ifndef TDENGINE_QSQLPARSER_H
+#define TDENGINE_QSQLPARSER_H
 
 #ifdef __cplusplus
 extern "C" {
@@ -329,4 +329,4 @@ int32_t tSQLParse(SSqlInfo *pSQLInfo, const char *pSql);
 }
 #endif
 
-#endif  // TDENGINE_QASTDEF_H
+#endif  // TDENGINE_QSQLPARSER_H
diff --git a/src/query/src/qast.c b/src/query/src/qast.c
index 192a7f39c0..4524c5b249 100644
--- a/src/query/src/qast.c
+++ b/src/query/src/qast.c
@@ -13,11 +13,11 @@
  * along with this program. If not, see <http://www.gnu.org/licenses/>.
  */
 
-#include "qast.h"
-#include <tarray.h>
-#include <tskiplist.h>
-#include "../../client/inc/tschemautil.h"
 #include "os.h"
+
+#include "tutil.h"
+#include "tbuffer.h"
+#include "qast.h"
 #include "qsqlparser.h"
 #include "qsyntaxtreefunction.h"
 #include "taosdef.h"
@@ -26,7 +26,10 @@
 #include "tsqlfunction.h"
 #include "tstoken.h"
 #include "ttokendef.h"
-#include "tutil.h"
+
+#include "../../client/inc/tschemautil.h"
+#include "tarray.h"
+#include "tskiplist.h"
 
 /*
  *
@@ -39,22 +42,20 @@
  * ver 0.3, pipeline filter in the form of: (a+2)/9 > 14
  *
  */
+static tExprNode *tExprNodeCreate(SSchema *pSchema, int32_t numOfCols, SSQLToken *pToken);
+static void       tExprNodeDestroy(tExprNode *pNode, void (*fp)(void *));
 
-static tSQLSyntaxNode *tSQLSyntaxNodeCreate(SSchema *pSchema, int32_t numOfCols, SSQLToken *pToken);
-static void            tSQLSyntaxNodeDestroy(tSQLSyntaxNode *pNode, void (*fp)(void *));
+static tExprNode *createSyntaxTree(SSchema *pSchema, int32_t numOfCols, char *str, int32_t *i);
+static void       destroySyntaxTree(tExprNode *);
 
-static tSQLSyntaxNode *createSyntaxTree(SSchema *pSchema, int32_t numOfCols, char *str, int32_t *i);
-static void            destroySyntaxTree(tSQLSyntaxNode *);
-
-static uint8_t isQueryOnPrimaryKey(const char *primaryColumnName, const tSQLSyntaxNode *pLeft,
-                                   const tSQLSyntaxNode *pRight);
+static uint8_t isQueryOnPrimaryKey(const char *primaryColumnName, const tExprNode *pLeft, const tExprNode *pRight);
 
 /*
  * Check the filter value type on the right hand side based on the column id on the left hand side,
  * the filter value type must be identical to field type for relational operation
  * As for binary arithmetic operation, it is not necessary to do so.
  */
-static void reviseBinaryExprIfNecessary(tSQLSyntaxNode **pLeft, tSQLSyntaxNode **pRight, uint8_t *optr) {
+static void reviseBinaryExprIfNecessary(tExprNode **pLeft, tExprNode **pRight, uint8_t *optr) {
   if (*optr >= TSDB_RELATION_LESS && *optr <= TSDB_RELATION_LIKE) {
     // make sure that the type of data on both sides of relational comparision are identical
     if ((*pLeft)->nodeType == TSQL_NODE_VALUE) {
@@ -79,7 +80,7 @@ static void reviseBinaryExprIfNecessary(tSQLSyntaxNode **pLeft, tSQLSyntaxNode *
    */
   if ((*pLeft)->nodeType == TSQL_NODE_VALUE && (*pRight)->nodeType == TSQL_NODE_COL) {
     if (*optr >= TSDB_RELATION_LARGE && *optr <= TSDB_RELATION_LARGE_EQUAL && *optr != TSDB_RELATION_EQUAL) {
-      SWAP(*pLeft, *pRight, tSQLSyntaxNode *);
+      SWAP(*pLeft, *pRight, tExprNode *);
     }
 
     switch (*optr) {
@@ -101,15 +102,15 @@ static void reviseBinaryExprIfNecessary(tSQLSyntaxNode **pLeft, tSQLSyntaxNode *
   }
 }
 
-static tSQLSyntaxNode *tSQLSyntaxNodeCreate(SSchema *pSchema, int32_t numOfCols, SSQLToken *pToken) {
+static tExprNode *tExprNodeCreate(SSchema *pSchema, int32_t numOfCols, SSQLToken *pToken) {
   /* if the token is not a value, return false */
   if (pToken->type == TK_RP || (pToken->type != TK_INTEGER && pToken->type != TK_FLOAT && pToken->type != TK_ID &&
                                 pToken->type != TK_TBNAME && pToken->type != TK_STRING && pToken->type != TK_BOOL)) {
     return NULL;
   }
 
-  size_t nodeSize = sizeof(tSQLSyntaxNode);
-  tSQLSyntaxNode *pNode = NULL;
+  size_t nodeSize = sizeof(tExprNode);
+  tExprNode *pNode = NULL;
 
   if (pToken->type == TK_ID || pToken->type == TK_TBNAME) {
     int32_t i = 0;
@@ -130,7 +131,7 @@ static tSQLSyntaxNode *tSQLSyntaxNodeCreate(SSchema *pSchema, int32_t numOfCols,
     nodeSize += sizeof(SSchema);
 
     pNode = calloc(1, nodeSize);
-    pNode->pSchema = (struct SSchema *)((char *)pNode + sizeof(tSQLSyntaxNode));
+    pNode->pSchema = (struct SSchema *)((char *)pNode + sizeof(tExprNode));
     pNode->nodeType = TSQL_NODE_COL;
 
     if (pToken->type == TK_ID) {
@@ -145,7 +146,7 @@ static tSQLSyntaxNode *tSQLSyntaxNodeCreate(SSchema *pSchema, int32_t numOfCols,
   } else {
     nodeSize += sizeof(tVariant);
     pNode = calloc(1, nodeSize);
-    pNode->pVal = (tVariant *)((char *)pNode + sizeof(tSQLSyntaxNode));
+    pNode->pVal = (tVariant *)((char *)pNode + sizeof(tExprNode));
 
     toTSDBType(pToken->type);
     tVariantCreate(pNode->pVal, pToken);
@@ -191,21 +192,21 @@ uint8_t getBinaryExprOptr(SSQLToken *pToken) {
 }
 
 // previous generated expr is reduced as the left child
-static tSQLSyntaxNode *parseRemainStr(char *pstr, tSQLSyntaxNode *pExpr, SSchema *pSchema, int32_t optr,
+static tExprNode *parseRemainStr(char *pstr, tExprNode *pExpr, SSchema *pSchema, int32_t optr,
                                       int32_t numOfCols, int32_t *i) {
   // set the previous generated node as the left child of new root
   pExpr->nodeType = TSQL_NODE_EXPR;
 
   // remain is the right child
-  tSQLSyntaxNode *pRight = createSyntaxTree(pSchema, numOfCols, pstr, i);
+  tExprNode *pRight = createSyntaxTree(pSchema, numOfCols, pstr, i);
   if (pRight == NULL || (pRight->nodeType == TSQL_NODE_COL && pExpr->nodeType != TSQL_NODE_VALUE) ||
       (pExpr->nodeType == TSQL_NODE_VALUE && pRight->nodeType != TSQL_NODE_COL)) {
-    tSQLSyntaxNodeDestroy(pExpr, NULL);
-    tSQLSyntaxNodeDestroy(pRight, NULL);
+    tExprNodeDestroy(pExpr, NULL);
+    tExprNodeDestroy(pRight, NULL);
     return NULL;
   }
 
-  tSQLSyntaxNode *pNewExpr = (tSQLSyntaxNode *)calloc(1, sizeof(tSQLSyntaxNode));
+  tExprNode *pNewExpr = (tExprNode *)calloc(1, sizeof(tExprNode));
   uint8_t         k = optr;
   reviseBinaryExprIfNecessary(&pExpr, &pRight, &k);
   pNewExpr->_node.pLeft = pExpr;
@@ -218,7 +219,7 @@ static tSQLSyntaxNode *parseRemainStr(char *pstr, tSQLSyntaxNode *pExpr, SSchema
   return pNewExpr;
 }
 
-uint8_t isQueryOnPrimaryKey(const char *primaryColumnName, const tSQLSyntaxNode *pLeft, const tSQLSyntaxNode *pRight) {
+uint8_t isQueryOnPrimaryKey(const char *primaryColumnName, const tExprNode *pLeft, const tExprNode *pRight) {
   if (pLeft->nodeType == TSQL_NODE_COL) {
     // if left node is the primary column,return true
     return (strcmp(primaryColumnName, pLeft->pSchema->name) == 0) ? 1 : 0;
@@ -231,20 +232,21 @@ uint8_t isQueryOnPrimaryKey(const char *primaryColumnName, const tSQLSyntaxNode
   }
 }
 
-static tSQLSyntaxNode *createSyntaxTree(SSchema *pSchema, int32_t numOfCols, char *str, int32_t *i) {
+static tExprNode *createSyntaxTree(SSchema *pSchema, int32_t numOfCols, char *str, int32_t *i) {
   SSQLToken t0 = tStrGetToken(str, i, false, 0, NULL);
   if (t0.n == 0) {
     return NULL;
   }
 
-  tSQLSyntaxNode *pLeft = NULL;
+  tExprNode *pLeft = NULL;
   if (t0.type == TK_LP) {  // start new left child branch
     pLeft = createSyntaxTree(pSchema, numOfCols, str, i);
   } else {
     if (t0.type == TK_RP) {
       return NULL;
     }
-    pLeft = tSQLSyntaxNodeCreate(pSchema, numOfCols, &t0);
+    
+    pLeft = tExprNodeCreate(pSchema, numOfCols, &t0);
   }
 
   if (pLeft == NULL) {
@@ -254,7 +256,7 @@ static tSQLSyntaxNode *createSyntaxTree(SSchema *pSchema, int32_t numOfCols, cha
   t0 = tStrGetToken(str, i, false, 0, NULL);
   if (t0.n == 0 || t0.type == TK_RP) {
     if (pLeft->nodeType != TSQL_NODE_EXPR) {  // if left is not the expr, it is not a legal expr
-      tSQLSyntaxNodeDestroy(pLeft, NULL);
+      tExprNodeDestroy(pLeft, NULL);
       return NULL;
     }
 
@@ -265,12 +267,12 @@ static tSQLSyntaxNode *createSyntaxTree(SSchema *pSchema, int32_t numOfCols, cha
   uint8_t optr = getBinaryExprOptr(&t0);
   if (optr == 0) {
     pError("not support binary operator:%d", t0.type);
-    tSQLSyntaxNodeDestroy(pLeft, NULL);
+    tExprNodeDestroy(pLeft, NULL);
     return NULL;
   }
 
   assert(pLeft != NULL);
-  tSQLSyntaxNode *pRight = NULL;
+  tExprNode *pRight = NULL;
 
   if (t0.type == TK_AND || t0.type == TK_OR || t0.type == TK_LP) {
     pRight = createSyntaxTree(pSchema, numOfCols, str, i);
@@ -283,51 +285,51 @@ static tSQLSyntaxNode *createSyntaxTree(SSchema *pSchema, int32_t numOfCols, cha
      */
     t0 = tStrGetToken(str, i, true, 0, NULL);
     if (t0.n == 0) {
-      tSQLSyntaxNodeDestroy(pLeft, NULL);  // illegal expression
+      tExprNodeDestroy(pLeft, NULL);  // illegal expression
       return NULL;
     }
 
     if (t0.type == TK_LP) {
       pRight = createSyntaxTree(pSchema, numOfCols, str, i);
     } else {
-      pRight = tSQLSyntaxNodeCreate(pSchema, numOfCols, &t0);
+      pRight = tExprNodeCreate(pSchema, numOfCols, &t0);
     }
   }
 
   if (pRight == NULL) {
-    tSQLSyntaxNodeDestroy(pLeft, NULL);
+    tExprNodeDestroy(pLeft, NULL);
     return NULL;
   }
 
   /* create binary expr as the child of new parent node */
-  tSQLSyntaxNode *pBinExpr = (tSQLSyntaxNode *)calloc(1, sizeof(tSQLSyntaxNode));
+  tExprNode *pExpr = (tExprNode *)calloc(1, sizeof(tExprNode));
   reviseBinaryExprIfNecessary(&pLeft, &pRight, &optr);
 
-  pBinExpr->_node.hasPK = isQueryOnPrimaryKey(pSchema[0].name, pLeft, pRight);
-  pBinExpr->_node.pLeft = pLeft;
-  pBinExpr->_node.pRight = pRight;
-  pBinExpr->_node.optr = optr;
+  pExpr->_node.hasPK = isQueryOnPrimaryKey(pSchema[0].name, pLeft, pRight);
+  pExpr->_node.pLeft = pLeft;
+  pExpr->_node.pRight = pRight;
+  pExpr->_node.optr = optr;
 
   t0 = tStrGetToken(str, i, true, 0, NULL);
 
   if (t0.n == 0 || t0.type == TK_RP) {
-    tSQLSyntaxNode *pn = malloc(sizeof(tSQLSyntaxNode));
-    pBinExpr->nodeType = TSQL_NODE_EXPR;
-    return pBinExpr;
+    pExpr->nodeType = TSQL_NODE_EXPR;
+    return pExpr;
   } else {
     uint8_t localOptr = getBinaryExprOptr(&t0);
     if (localOptr == 0) {
       pError("not support binary operator:%d", t0.type);
-      free(pBinExpr);
+      free(pExpr);
       return NULL;
     }
 
-    return parseRemainStr(str, pBinExpr, pSchema, localOptr, numOfCols, i);
+    return parseRemainStr(str, pExpr, pSchema, localOptr, numOfCols, i);
   }
 }
 
-void tSQLBinaryExprFromString(tSQLSyntaxNode **pExpr, SSchema *pSchema, int32_t numOfCols, char *src, int32_t len) {
+void tSQLBinaryExprFromString(tExprNode **pExpr, SSchema *pSchema, int32_t numOfCols, char *src, int32_t len) {
   *pExpr = NULL;
+  
   if (len <= 0 || src == NULL || pSchema == NULL || numOfCols <= 0) {
     return;
   }
@@ -340,7 +342,7 @@ void tSQLBinaryExprFromString(tSQLSyntaxNode **pExpr, SSchema *pSchema, int32_t
   }
 }
 
-int32_t tSQLBinaryExprToStringImpl(tSQLSyntaxNode *pNode, char *dst, uint8_t type) {
+int32_t tSQLBinaryExprToStringImpl(tExprNode *pNode, char *dst, uint8_t type) {
   int32_t len = 0;
   if (type == TSQL_NODE_EXPR) {
     *dst = '(';
@@ -406,7 +408,7 @@ static char *tSQLOptrToString(uint8_t optr, char *dst) {
   return dst;
 }
 
-void tSQLBinaryExprToString(tSQLSyntaxNode *pExpr, char *dst, int32_t *len) {
+void tSQLBinaryExprToString(tExprNode *pExpr, char *dst, int32_t *len) {
   if (pExpr == NULL) {
     *dst = 0;
     *len = 0;
@@ -423,32 +425,41 @@ void tSQLBinaryExprToString(tSQLSyntaxNode *pExpr, char *dst, int32_t *len) {
   *len += tSQLBinaryExprToStringImpl(pExpr->_node.pRight, start, pExpr->_node.pRight->nodeType);
 }
 
-static void UNUSED_FUNC destroySyntaxTree(tSQLSyntaxNode *pNode) { tSQLSyntaxNodeDestroy(pNode, NULL); }
+static void UNUSED_FUNC destroySyntaxTree(tExprNode *pNode) { tExprNodeDestroy(pNode, NULL); }
 
-static void tSQLSyntaxNodeDestroy(tSQLSyntaxNode *pNode, void (*fp)(void *)) {
+static void tExprNodeDestroy(tExprNode *pNode, void (*fp)(void *)) {
   if (pNode == NULL) {
     return;
   }
 
   if (pNode->nodeType == TSQL_NODE_EXPR) {
-    tSQLBinaryExprDestroy(&pNode, fp);
+    tExprTreeDestroy(&pNode, fp);
   } else if (pNode->nodeType == TSQL_NODE_VALUE) {
     tVariantDestroy(pNode->pVal);
+  } else if (pNode->nodeType == TSQL_NODE_COL) {
+    free(pNode->pSchema);
   }
 
   free(pNode);
 }
 
-void tSQLBinaryExprDestroy(tSQLSyntaxNode **pExpr, void (*fp)(void *)) {
+void tExprTreeDestroy(tExprNode **pExpr, void (*fp)(void *)) {
   if (*pExpr == NULL) {
     return;
   }
-
-  tSQLSyntaxNodeDestroy((*pExpr)->_node.pLeft, fp);
-  tSQLSyntaxNodeDestroy((*pExpr)->_node.pRight, fp);
-
-  if (fp != NULL) {
-    fp((*pExpr)->_node.info);
+  
+  if ((*pExpr)->nodeType == TSQL_NODE_EXPR) {
+    tExprTreeDestroy(&(*pExpr)->_node.pLeft, fp);
+    tExprTreeDestroy(&(*pExpr)->_node.pRight, fp);
+  
+    if (fp != NULL) {
+      fp((*pExpr)->_node.info);
+    }
+  } else if ((*pExpr)->nodeType == TSQL_NODE_VALUE) {
+    tVariantDestroy((*pExpr)->pVal);
+    free((*pExpr)->pVal);
+  } else if ((*pExpr)->nodeType == TSQL_NODE_COL) {
+    free((*pExpr)->pSchema);
   }
 
   free(*pExpr);
@@ -559,7 +570,7 @@ void tSQLBinaryExprDestroy(tSQLSyntaxNode **pExpr, void (*fp)(void *)) {
 //  DEFAULT_COMP(p1, p2);
 //}
 
-int32_t merge(tQueryResultset *pLeft, tQueryResultset *pRight, tQueryResultset *pFinalRes) {
+int32_t merge(SArray *pLeft, SArray *pRight, SArray *pFinalRes) {
 //  assert(pFinalRes->pRes == 0);
 //
 //  pFinalRes->pRes = calloc((size_t)(pLeft->num + pRight->num), POINTER_BYTES);
@@ -600,7 +611,7 @@ int32_t merge(tQueryResultset *pLeft, tQueryResultset *pRight, tQueryResultset *
   return 0;
 }
 
-int32_t intersect(tQueryResultset *pLeft, tQueryResultset *pRight, tQueryResultset *pFinalRes) {
+int32_t intersect(SArray *pLeft, SArray *pRight, SArray *pFinalRes) {
 //  int64_t num = MIN(pLeft->num, pRight->num);
 //
 //  assert(pFinalRes->pRes == 0);
@@ -638,25 +649,26 @@ int32_t intersect(tQueryResultset *pLeft, tQueryResultset *pRight, tQueryResults
 /*
  * traverse the result and apply the function to each item to check if the item is qualified or not
  */
-static UNUSED_FUNC void tSQLListTraverseOnResult(struct tSQLSyntaxNode *pExpr, __result_filter_fn_t fp, tQueryResultset *pResult) {
-  assert(pExpr->_node.pLeft->nodeType == TSQL_NODE_COL && pExpr->_node.pRight->nodeType == TSQL_NODE_VALUE);
-
-  // brutal force scan the result list and check for each item in the list
-  int64_t num = pResult->num;
-  for (int32_t i = 0, j = 0; i < pResult->num; ++i) {
-    if (fp == NULL || (fp(pResult->pRes[i], pExpr->_node.info) == true)) {
-      pResult->pRes[j++] = pResult->pRes[i];
-    } else {
-      num--;
-    }
-  }
-
-  pResult->num = num;
+static UNUSED_FUNC void tSQLListTraverseOnResult(struct tExprNode *pExpr, __result_filter_fn_t fp, SArray *pResult) {
+//  assert(pExpr->_node.pLeft->nodeType == TSQL_NODE_COL && pExpr->_node.pRight->nodeType == TSQL_NODE_VALUE);
+//
+//  // brutal force scan the result list and check for each item in the list
+//  int64_t num = pResult->num;
+//  for (int32_t i = 0, j = 0; i < pResult->num; ++i) {
+//    if (fp == NULL || (fp(pResult->pRes[i], pExpr->_node.info) == true)) {
+//      pResult->pRes[j++] = pResult->pRes[i];
+//    } else {
+//      num--;
+//    }
+//  }
+//
+//  pResult->num = num;
+  assert(0);
 }
 
-static bool filterItem(tSQLSyntaxNode *pExpr, const void *pItem, SBinaryFilterSupp *param) {
-  tSQLSyntaxNode *pLeft = pExpr->_node.pLeft;
-  tSQLSyntaxNode *pRight = pExpr->_node.pRight;
+static bool filterItem(tExprNode *pExpr, const void *pItem, SBinaryFilterSupp *param) {
+  tExprNode *pLeft = pExpr->_node.pLeft;
+  tExprNode *pRight = pExpr->_node.pRight;
 
   /*
    * non-leaf nodes, recursively traverse the syntax tree in the post-root order
@@ -695,7 +707,7 @@ static bool filterItem(tSQLSyntaxNode *pExpr, const void *pItem, SBinaryFilterSu
  * @param pSchema   tag schemas
  * @param fp        filter callback function
  */
-static void tSQLBinaryTraverseOnResult(tSQLSyntaxNode *pExpr, SArray *pResult, SBinaryFilterSupp *param) {
+static void tSQLBinaryTraverseOnResult(tExprNode *pExpr, SArray *pResult, SBinaryFilterSupp *param) {
   size_t size = taosArrayGetSize(pResult);
   
   SArray* array = taosArrayInit(size, POINTER_BYTES);
@@ -710,7 +722,7 @@ static void tSQLBinaryTraverseOnResult(tSQLSyntaxNode *pExpr, SArray *pResult, S
   taosArrayCopy(pResult, array);
 }
 
-static void tSQLBinaryTraverseOnSkipList(tSQLSyntaxNode *pExpr, SArray *pResult, SSkipList *pSkipList,
+static void tSQLBinaryTraverseOnSkipList(tExprNode *pExpr, SArray *pResult, SSkipList *pSkipList,
     SBinaryFilterSupp *param) {
   SSkipListIterator* iter = tSkipListCreateIter(pSkipList);
 
@@ -724,13 +736,13 @@ static void tSQLBinaryTraverseOnSkipList(tSQLSyntaxNode *pExpr, SArray *pResult,
 }
 
 // post-root order traverse syntax tree
-void tSQLBinaryExprTraverse(tSQLSyntaxNode *pExpr, SSkipList *pSkipList, SArray *result, SBinaryFilterSupp *param) {
+void tSQLBinaryExprTraverse(tExprNode *pExpr, SSkipList *pSkipList, SArray *result, SBinaryFilterSupp *param) {
   if (pExpr == NULL) {
     return;
   }
 
-  tSQLSyntaxNode *pLeft = pExpr->_node.pLeft;
-  tSQLSyntaxNode *pRight = pExpr->_node.pRight;
+  tExprNode *pLeft = pExpr->_node.pLeft;
+  tExprNode *pRight = pExpr->_node.pRight;
 
   // recursive traverse left child branch
   if (pLeft->nodeType == TSQL_NODE_EXPR || pRight->nodeType == TSQL_NODE_EXPR) {
@@ -751,22 +763,22 @@ void tSQLBinaryExprTraverse(tSQLSyntaxNode *pExpr, SSkipList *pSkipList, SArray
       assert(taosArrayGetSize(result) == 0);
       tSQLBinaryTraverseOnSkipList(pExpr, result, pSkipList, param);
     } else if (weight == 2 || (weight == 1 && pExpr->_node.optr == TSDB_RELATION_OR)) {
-      tQueryResultset rLeft = {0};
-      tQueryResultset rRight = {0};
+      SArray* rLeft  = taosArrayInit(10, POINTER_BYTES);
+      SArray* rRight = taosArrayInit(10, POINTER_BYTES);
 
-      tSQLBinaryExprTraverse(pLeft, pSkipList, &rLeft, param);
-      tSQLBinaryExprTraverse(pRight, pSkipList, &rRight, param);
+      tSQLBinaryExprTraverse(pLeft, pSkipList, rLeft, param);
+      tSQLBinaryExprTraverse(pRight, pSkipList, rRight, param);
 
       if (pExpr->_node.optr == TSDB_RELATION_AND) {  // CROSS
-        intersect(&rLeft, &rRight, result);
+        intersect(rLeft, rRight, result);
       } else if (pExpr->_node.optr == TSDB_RELATION_OR) {  // or
-        merge(&rLeft, &rRight, result);
+        merge(rLeft, rRight, result);
       } else {
         assert(false);
       }
 
-      free(rLeft.pRes);
-      free(rRight.pRes);
+      taosArrayDestroy(rLeft);
+      taosArrayDestroy(rRight);
     } else {
       /*
        * (weight == 1 && pExpr->nSQLBinaryOptr == TSDB_RELATION_AND) is handled here
@@ -776,8 +788,8 @@ void tSQLBinaryExprTraverse(tSQLSyntaxNode *pExpr, SSkipList *pSkipList, SArray
        */
       assert(pExpr->_node.optr == TSDB_RELATION_AND);
 
-      tSQLSyntaxNode *pFirst = NULL;
-      tSQLSyntaxNode *pSecond = NULL;
+      tExprNode *pFirst = NULL;
+      tExprNode *pSecond = NULL;
       if (pLeft->_node.hasPK == 1) {
         pFirst = pLeft;
         pSecond = pRight;
@@ -810,14 +822,14 @@ void tSQLBinaryExprTraverse(tSQLSyntaxNode *pExpr, SSkipList *pSkipList, SArray
   }
 }
 
-void tSQLBinaryExprCalcTraverse(tSQLSyntaxNode *pExprs, int32_t numOfRows, char *pOutput, void *param, int32_t order,
+void tSQLBinaryExprCalcTraverse(tExprNode *pExprs, int32_t numOfRows, char *pOutput, void *param, int32_t order,
                                 char *(*getSourceDataBlock)(void *, char *, int32_t)) {
   if (pExprs == NULL) {
     return;
   }
 
-  tSQLSyntaxNode *pLeft = pExprs->_node.pLeft;
-  tSQLSyntaxNode *pRight = pExprs->_node.pRight;
+  tExprNode *pLeft = pExprs->_node.pLeft;
+  tExprNode *pRight = pExprs->_node.pRight;
 
   /* the left output has result from the left child syntax tree */
   char *pLeftOutput = (char*)malloc(sizeof(int64_t) * numOfRows);
@@ -890,13 +902,13 @@ void tSQLBinaryExprCalcTraverse(tSQLSyntaxNode *pExprs, int32_t numOfRows, char
   free(pRightOutput);
 }
 
-void tSQLBinaryExprTrv(tSQLSyntaxNode *pExprs, int32_t *val, int16_t *ids) {
+void tSQLBinaryExprTrv(tExprNode *pExprs, int32_t *val, int16_t *ids) {
   if (pExprs == NULL) {
     return;
   }
 
-  tSQLSyntaxNode *pLeft = pExprs->_node.pLeft;
-  tSQLSyntaxNode *pRight = pExprs->_node.pRight;
+  tExprNode *pLeft = pExprs->_node.pLeft;
+  tExprNode *pRight = pExprs->_node.pRight;
 
   // recursive traverse left child branch
   if (pLeft->nodeType == TSQL_NODE_EXPR) {
@@ -914,11 +926,97 @@ void tSQLBinaryExprTrv(tSQLSyntaxNode *pExprs, int32_t *val, int16_t *ids) {
   }
 }
 
-void tQueryResultClean(tQueryResultset *pRes) {
-  if (pRes == NULL) {
-    return;
+static int32_t exprTreeToBinaryImpl(tExprNode* pExprTree, SBuffer* pBuf) {
+  tbufWrite(pBuf, &pExprTree->nodeType, sizeof(pExprTree->nodeType));
+  
+  if (pExprTree->nodeType == TSQL_NODE_VALUE) {
+    tVariant* pVal = pExprTree->pVal;
+    
+    tbufWrite(pBuf, &pVal->nType, sizeof(pVal->nType));
+    if (pVal->nType == TSDB_DATA_TYPE_BINARY) {
+      tbufWrite(pBuf, &pVal->nLen, sizeof(pVal->nLen));
+      tbufWrite(pBuf, pVal->pz, pVal->nLen);
+    } else {
+      tbufWrite(pBuf, &pVal->pz, sizeof(pVal->i64Key));
+    }
+    
+  } else if (pExprTree->nodeType == TSQL_NODE_COL) {
+    SSchema* pSchema = pExprTree->pSchema;
+    tbufWrite(pBuf, &pSchema->colId, sizeof(pSchema->colId));
+    tbufWrite(pBuf, &pSchema->bytes, sizeof(pSchema->bytes));
+    tbufWrite(pBuf, &pSchema->type, sizeof(pSchema->type));
+    
+    int32_t len = strlen(pSchema->name);
+    tbufWriteStringLen(pBuf, pSchema->name, len);
+    
+  } else if (pExprTree->nodeType == TSQL_NODE_EXPR) {
+    tbufWrite(pBuf, &pExprTree->_node.optr, sizeof(pExprTree->_node.optr));
+    tbufWrite(pBuf, &pExprTree->_node.hasPK, sizeof(pExprTree->_node.hasPK));
+  
+    exprTreeToBinaryImpl(pExprTree->_node.pLeft, pBuf);
+    exprTreeToBinaryImpl(pExprTree->_node.pRight, pBuf);
   }
-
-  tfree(pRes->pRes);
-  pRes->num = 0;
 }
+
+SBuffer exprTreeToBinary(tExprNode* pExprTree) {
+  SBuffer buf = {0};
+  if (pExprTree == NULL) {
+    return buf;
+  }
+  
+  int32_t code = tbufBeginWrite(&buf);
+  if (code != 0) {
+    return buf;
+  }
+  
+  exprTreeToBinaryImpl(pExprTree, &buf);
+  return buf;
+}
+
+static tExprNode* exprTreeFromBinaryImpl(tExprNode** pExprTree, SBuffer* pBuf) {
+  tExprNode* pExpr = calloc(1, sizeof(tExprNode));
+  tbufReadToBuffer(pBuf, &pExpr->nodeType, sizeof(pExpr->nodeType));
+  
+  if (pExpr->nodeType == TSQL_NODE_VALUE) {
+    tVariant* pVal = calloc(1, sizeof(tVariant));
+  
+    tbufReadToBuffer(pBuf, &pVal->nType, sizeof(pVal->nType));
+    if (pVal->nType == TSDB_DATA_TYPE_BINARY) {
+      tbufReadToBuffer(pBuf, &pVal->nLen, sizeof(pVal->nLen));
+      pVal->pz = calloc(1, pVal->nLen + 1);
+      tbufReadToBuffer(pBuf, pVal->pz, pVal->nLen);
+    } else {
+      tbufReadToBuffer(pBuf, &pVal->pz, sizeof(pVal->i64Key));
+    }
+    
+    pExpr->pVal = pVal;
+  } else if (pExpr->nodeType == TSQL_NODE_COL) {
+    SSchema* pSchema = calloc(1, sizeof(SSchema));
+    tbufReadToBuffer(pBuf, &pSchema->colId, sizeof(pSchema->colId));
+    tbufReadToBuffer(pBuf, &pSchema->bytes, sizeof(pSchema->bytes));
+    tbufReadToBuffer(pBuf, &pSchema->type, sizeof(pSchema->type));
+    
+    tbufReadToString(pBuf, pSchema->name, TSDB_COL_NAME_LEN);
+    
+    pExpr->pSchema = pSchema;
+  } else if (pExpr->nodeType == TSQL_NODE_EXPR) {
+    tbufReadToBuffer(pBuf, &pExpr->_node.optr, sizeof(pExpr->_node.optr));
+    tbufReadToBuffer(pBuf, &pExpr->_node.hasPK, sizeof(pExpr->_node.hasPK));
+  
+    exprTreeFromBinaryImpl(&pExpr->_node.pLeft, pBuf);
+    exprTreeFromBinaryImpl(&pExpr->_node.pRight, pBuf);
+    
+    assert(pExpr->_node.pLeft != NULL && pExpr->_node.pRight != NULL);
+  }
+  
+  *pExprTree = pExpr;
+}
+
+tExprNode* exprTreeFromBinary(const void* pBuf, size_t size) {
+  SBuffer rbuf = {0};
+  int32_t code = tbufBeginRead(&rbuf, pBuf, size);
+  
+  tExprNode* pExprNode = NULL;
+  exprTreeFromBinaryImpl(&pExprNode, &rbuf);
+  return pExprNode;
+}
\ No newline at end of file
diff --git a/src/query/src/qtokenizer.c b/src/query/src/qtokenizer.c
index 61d2e59c87..51b196a9da 100644
--- a/src/query/src/qtokenizer.c
+++ b/src/query/src/qtokenizer.c
@@ -13,10 +13,10 @@
  * along with this program. If not, see <http://www.gnu.org/licenses/>.
  */
 
+#include "os.h"
+
 #include "hash.h"
 #include "hashfunc.h"
-#include "os.h"
-#include "shash.h"
 #include "taosdef.h"
 #include "tstoken.h"
 #include "ttokendef.h"
diff --git a/src/query/src/queryExecutor.c b/src/query/src/queryExecutor.c
index a32c8638ce..932c043377 100644
--- a/src/query/src/queryExecutor.c
+++ b/src/query/src/queryExecutor.c
@@ -2609,7 +2609,6 @@ static int64_t doScanAllDataBlocks(SQueryRuntimeEnv *pRuntimeEnv) {
          GET_QINFO_ADDR(pRuntimeEnv), pQuery->window.skey, pQuery->window.ekey, pQuery->lastKey, pQuery->order.order);
 
   tsdb_query_handle_t pQueryHandle = pRuntimeEnv->pQueryHandle;
-
   while (tsdbNextDataBlock(pQueryHandle)) {
     // check if query is killed or not set the status of query to pass the status check
     if (isQueryKilled(GET_QINFO_ADDR(pRuntimeEnv))) {
@@ -5149,7 +5148,7 @@ static void singleTableQueryImpl(SQInfo* pQInfo) {
   int64_t st = taosGetTimestampUs();
   
   // group by normal column, sliding window query, interval query are handled by interval query processor
-  if (pQuery->intervalTime != 0 || isGroupbyNormalCol(pQuery->pGroupbyExpr)) {  // interval (down sampling operation)
+  if (isIntervalQuery(pQuery) || isGroupbyNormalCol(pQuery->pGroupbyExpr)) {  // interval (down sampling operation)
     tableIntervalProcessor(pQInfo);
   } else {
     if (isFixedOutputQuery(pQuery)) {
@@ -5461,7 +5460,7 @@ static int32_t buildAirthmeticExprFromMsg(SSqlFunctionExpr *pExpr, SQueryTableMs
   SSqlBinaryExprInfo *pBinaryExprInfo = &pExpr->binExprInfo;
   SColumnInfo *       pColMsg = pQueryMsg->colList;
 #if 0
-  tSQLSyntaxNode* pBinExpr = NULL;
+  tExprNode* pBinExpr = NULL;
   SSchema*        pSchema = toSchema(pQueryMsg, pColMsg, pQueryMsg->numOfCols);
   
   dTrace("qmsg:%p create binary expr from string:%s", pQueryMsg, pExpr->pBase.arg[0].argValue.pz);
@@ -5962,7 +5961,7 @@ static void freeQInfo(SQInfo *pQInfo) {
       
       if (pBinExprInfo->numOfCols > 0) {
         tfree(pBinExprInfo->pReqColumns);
-        tSQLBinaryExprDestroy(&pBinExprInfo->pBinExpr, NULL);
+        tExprTreeDestroy(&pBinExprInfo->pBinExpr, NULL);
       }
     }
     
diff --git a/src/query/src/queryUtil.c b/src/query/src/queryUtil.c
index d954c10849..17410b2868 100644
--- a/src/query/src/queryUtil.c
+++ b/src/query/src/queryUtil.c
@@ -24,6 +24,7 @@
 #include "ttime.h"
 
 #include "queryExecutor.h"
+#include "queryUtil.h"
 
 int32_t initWindowResInfo(SWindowResInfo *pWindowResInfo, SQueryRuntimeEnv *pRuntimeEnv, int32_t size,
                           int32_t threshold, int16_t type) {
diff --git a/src/query/tests/astTest.cpp b/src/query/tests/astTest.cpp
new file mode 100644
index 0000000000..ac10cd2429
--- /dev/null
+++ b/src/query/tests/astTest.cpp
@@ -0,0 +1,630 @@
+#include <gtest/gtest.h>
+#include <qast.h>
+#include <sys/time.h>
+#include <cassert>
+#include <iostream>
+
+#include "qast.h"
+#include "taosmsg.h"
+#include "tsdb.h"
+#include "tskiplist.h"
+
+typedef struct ResultObj {
+  int32_t numOfResult;
+  char *  resultName[64];
+} ResultObj;
+
+static void initSchema(SSchema *pSchema, int32_t numOfCols);
+
+static void initSchema_binary(SSchema *schema, int32_t numOfCols);
+
+static tSkipList *createSkipList(SSchema *pSchema, int32_t numOfTags);
+static tSkipList *createSkipList_binary(SSchema *pSchema, int32_t numOfTags);
+
+static void testQueryStr(SSchema *schema, int32_t numOfCols, char *sql, tSkipList *pSkipList, ResultObj *expectedVal);
+
+static void dropMeter(tSkipList *pSkipList);
+
+static void Right2LeftTest(SSchema *schema, int32_t numOfCols, tSkipList *pSkipList);
+
+static void Left2RightTest(SSchema *schema, int32_t numOfCols, tSkipList *pSkipList);
+
+static void IllegalExprTest(SSchema *schema, int32_t numOfCols, tSkipList *pSkipList);
+
+static void Left2RightTest_binary(SSchema *schema, int32_t numOfCols, tSkipList *pSkipList);
+static void Right2LeftTest_binary(SSchema *schema, int32_t numOfCols, tSkipList *pSkipList);
+
+void setValue(ResultObj *pResult, int32_t num, char **val) {
+  pResult->numOfResult = num;
+  for (int32_t i = 0; i < num; ++i) {
+    pResult->resultName[i] = val[i];
+  }
+}
+
+static void initSchema_binary(SSchema *schema, int32_t numOfCols) {
+  schema[0].type = TSDB_DATA_TYPE_BINARY;
+  schema[0].bytes = 8;
+  strcpy(schema[0].name, "a");
+
+  schema[1].type = TSDB_DATA_TYPE_DOUBLE;
+  schema[1].bytes = 8;
+  strcpy(schema[1].name, "b");
+
+  schema[2].type = TSDB_DATA_TYPE_INT;
+  schema[2].bytes = 20;
+  strcpy(schema[2].name, "c");
+
+  schema[3].type = TSDB_DATA_TYPE_BIGINT;
+  schema[3].bytes = 8;
+  strcpy(schema[3].name, "d");
+
+  schema[4].type = TSDB_DATA_TYPE_SMALLINT;
+  schema[4].bytes = 2;
+  strcpy(schema[4].name, "e");
+
+  schema[5].type = TSDB_DATA_TYPE_TINYINT;
+  schema[5].bytes = 1;
+  strcpy(schema[5].name, "f");
+
+  schema[6].type = TSDB_DATA_TYPE_FLOAT;
+  schema[6].bytes = 4;
+  strcpy(schema[6].name, "g");
+
+  schema[7].type = TSDB_DATA_TYPE_BOOL;
+  schema[7].bytes = 1;
+  strcpy(schema[7].name, "h");
+}
+
+static void initSchema(SSchema *schema, int32_t numOfCols) {
+  schema[0].type = TSDB_DATA_TYPE_INT;
+  schema[0].bytes = 8;
+  strcpy(schema[0].name, "a");
+
+  schema[1].type = TSDB_DATA_TYPE_DOUBLE;
+  schema[1].bytes = 8;
+  strcpy(schema[1].name, "b");
+
+  schema[2].type = TSDB_DATA_TYPE_BINARY;
+  schema[2].bytes = 20;
+  strcpy(schema[2].name, "c");
+
+  schema[3].type = TSDB_DATA_TYPE_BIGINT;
+  schema[3].bytes = 8;
+  strcpy(schema[3].name, "d");
+
+  schema[4].type = TSDB_DATA_TYPE_SMALLINT;
+  schema[4].bytes = 2;
+  strcpy(schema[4].name, "e");
+
+  schema[5].type = TSDB_DATA_TYPE_TINYINT;
+  schema[5].bytes = 1;
+  strcpy(schema[5].name, "f");
+
+  schema[6].type = TSDB_DATA_TYPE_FLOAT;
+  schema[6].bytes = 4;
+  strcpy(schema[6].name, "g");
+
+  schema[7].type = TSDB_DATA_TYPE_BOOL;
+  schema[7].bytes = 1;
+  strcpy(schema[7].name, "h");
+}
+
+// static void addOneNode(SSchema *pSchema, int32_t tagsLen, tSkipList *pSkipList,
+//                       char *meterId, int32_t a, double b, char *c, int64_t d, int16_t e, int8_t f, float g,
+//                       bool h, int32_t numOfTags) {
+//  STabObj *pMeter = calloc(1, sizeof(STabObj));
+//  pMeter->numOfTags = numOfTags;
+//  pMeter->pTagData = calloc(1, tagsLen + TSDB_METER_ID_LEN);
+//  strcpy(pMeter->meterId, meterId);
+//
+//  char *tags = pMeter->pTagData + TSDB_METER_ID_LEN;
+//  int32_t offset = 0;
+//
+//  *(int32_t *) tags = a;
+//
+//  offset += pSchema[0].bytes;
+//  *(double *) (tags + offset) = b;
+//
+//  offset += pSchema[1].bytes;
+//  memcpy(tags + offset, c, 3);
+//
+//  offset += pSchema[2].bytes;
+//  *(int64_t *) (tags + offset) = d;
+//
+//  offset += pSchema[3].bytes;
+//  *(int16_t *) (tags + offset) = e;
+//
+//  offset += pSchema[4].bytes;
+//  *(int8_t *) (tags + offset) = f;
+//
+//  offset += pSchema[5].bytes;
+//  *(float *) (tags + offset) = g;
+//
+//  offset += pSchema[6].bytes;
+//  *(int8_t *) (tags + offset) = h ? 1 : 0;
+//
+//  tSkipListKey pKey = tSkipListCreateKey(pSchema[0].type, tags, pSchema[0].bytes);
+//  tSkipListPut(pSkipList, pMeter, &pKey, 1);
+//}
+//
+// static void addOneNode_binary(SSchema *pSchema, int32_t tagsLen, tSkipList *pSkipList,
+//                              char *meterId, int32_t a, double b, char *c, int64_t d, int16_t e, int8_t f, float g,
+//                              bool h, int32_t numOfTags) {
+//  STabObj *pMeter = calloc(1, sizeof(STabObj));
+//  pMeter->numOfTags = numOfTags;
+//  pMeter->pTagData = calloc(1, tagsLen + TSDB_METER_ID_LEN);
+//  strcpy(pMeter->meterId, meterId);
+//
+//  char *tags = pMeter->pTagData + TSDB_METER_ID_LEN;
+//  int32_t offset = 0;
+//  memcpy(tags, c, pSchema[0].bytes);
+//
+//  offset += pSchema[0].bytes;
+//  *(double *) (tags + offset) = b;
+//
+//  offset += pSchema[1].bytes;
+//  *(int32_t *) (tags + offset) = a;
+//
+//  offset += pSchema[2].bytes;
+//  *(int64_t *) (tags + offset) = d;
+//
+//  offset += pSchema[3].bytes;
+//  *(int16_t *) (tags + offset) = e;
+//
+//  offset += pSchema[4].bytes;
+//  *(int8_t *) (tags + offset) = f;
+//
+//  offset += pSchema[5].bytes;
+//  *(float *) (tags + offset) = g;
+//
+//  offset += pSchema[6].bytes;
+//  *(int8_t *) (tags + offset) = h ? 1 : 0;
+//
+//  tSkipListKey pKey = tSkipListCreateKey(pSchema[0].type, tags, pSchema[0].bytes);
+//  tSkipListPut(pSkipList, pMeter, &pKey, 1);
+//  tSkipListDestroyKey(&pKey);
+//}
+
+// static void dropMeter(tSkipList *pSkipList) {
+//  tSkipListNode **pRes = NULL;
+//  int32_t num = tSkipListIterateList(pSkipList, &pRes, NULL, NULL);
+//  for (int32_t i = 0; i < num; ++i) {
+//    tSkipListNode *pNode = pRes[i];
+//    STabObj *pMeter = (STabObj *) pNode->pData;
+//    free(pMeter->pTagData);
+//    free(pMeter);
+//    pNode->pData = NULL;
+//  }
+//  free(pRes);
+//}
+
+// static tSkipList *createSkipList(SSchema *pSchema, int32_t numOfTags) {
+//  int32_t tagsLen = 0;
+//  for (int32_t i = 0; i < numOfTags; ++i) {
+//    tagsLen += pSchema[i].bytes;
+//  }
+//
+//  tSkipList *pSkipList = tSkipListCreate(10, pSchema[0].type, 4);
+//
+//  addOneNode(pSchema, tagsLen, pSkipList, "tm0\0", 0, 10.5, "abc", 1000, -10000, -20, 1.0, true, 8);
+//  addOneNode(pSchema, tagsLen, pSkipList, "tm1\0", 1, 20.5, "def", 1100, -10500, -30, 2.0, false, 8);
+//  addOneNode(pSchema, tagsLen, pSkipList, "tm2\0", 2, 30.5, "ghi", 1200, -11000, -40, 3.0, true, 8);
+//  addOneNode(pSchema, tagsLen, pSkipList, "tm3\0", 3, 40.5, "jkl", 1300, -11500, -50, 4.0, false, 8);
+//  addOneNode(pSchema, tagsLen, pSkipList, "tm4\0", 4, 50.5, "mno", 1400, -12000, -60, 5.0, true, 8);
+//  addOneNode(pSchema, tagsLen, pSkipList, "tm5\0", 5, 60.5, "pqr", 1500, -12500, -70, 6.0, false, 8);
+//  addOneNode(pSchema, tagsLen, pSkipList, "tm6\0", 6, 70.5, "stu", 1600, -13000, -80, 7.0, true, 8);
+//
+//  return pSkipList;
+//}
+//
+// static tSkipList *createSkipList_binary(SSchema *pSchema, int32_t numOfTags) {
+//  int32_t tagsLen = 0;
+//  for (int32_t i = 0; i < numOfTags; ++i) {
+//    tagsLen += pSchema[i].bytes;
+//  }
+//
+//  tSkipList *pSkipList = tSkipListCreate(10, pSchema[0].type, 4);
+//
+//  addOneNode_binary(pSchema, tagsLen, pSkipList, "tm0\0", 0, 10.5, "abc", 1000, -10000, -20, 1.0, true, 8);
+//  addOneNode_binary(pSchema, tagsLen, pSkipList, "tm1\0", 1, 20.5, "def", 1100, -10500, -30, 2.0, false, 8);
+//  addOneNode_binary(pSchema, tagsLen, pSkipList, "tm2\0", 2, 30.5, "ghi", 1200, -11000, -40, 3.0, true, 8);
+//  addOneNode_binary(pSchema, tagsLen, pSkipList, "tm3\0", 3, 40.5, "jkl", 1300, -11500, -50, 4.0, false, 8);
+//  addOneNode_binary(pSchema, tagsLen, pSkipList, "tm4\0", 4, 50.5, "mno", 1400, -12000, -60, 5.0, true, 8);
+//  addOneNode_binary(pSchema, tagsLen, pSkipList, "tm5\0", 5, 60.5, "pqr", 1500, -12500, -70, 6.0, false, 8);
+//  addOneNode_binary(pSchema, tagsLen, pSkipList, "tm6\0", 6, 70.5, "stu", 1600, -13000, -80, 7.0, true, 8);
+//
+//  return pSkipList;
+//}
+
+static void testQueryStr(SSchema *schema, int32_t numOfCols, char *sql, tSkipList *pSkipList, ResultObj *pResult) {
+  tExprNode *pExpr = NULL;
+  tSQLBinaryExprFromString(&pExpr, schema, numOfCols, sql, strlen(sql));
+
+  char    str[512] = {0};
+  int32_t len = 0;
+  if (pExpr == NULL) {
+    printf("-----error in parse syntax:%s\n\n", sql);
+    assert(pResult == NULL);
+    return;
+  }
+
+  tSQLBinaryExprToString(pExpr, str, &len);
+  printf("expr is: %s\n", str);
+
+  SArray *result = NULL;
+  //  tSQLBinaryExprTraverse(pExpr, pSkipList, result, tSkipListNodeFilterCallback, &result);
+  //  printf("the result is:%lld\n", result.num);
+  //
+  //  bool findResult = false;
+  //  for (int32_t i = 0; i < result.num; ++i) {
+  //    STabObj *pm = (STabObj *)result.pRes[i];
+  //    printf("meterid:%s,\t", pm->meterId);
+  //
+  //    for (int32_t j = 0; j < pResult->numOfResult; ++j) {
+  //      if (strcmp(pm->meterId, pResult->resultName[j]) == 0) {
+  //        findResult = true;
+  //        break;
+  //      }
+  //    }
+  //    assert(findResult == true);
+  //    findResult = false;
+  //  }
+
+  printf("\n\n");
+  tExprTreeDestroy(&pExpr, NULL);
+}
+
+static void Left2RightTest(SSchema *schema, int32_t numOfCols, tSkipList *pSkipList) {
+  char str[256] = {0};
+
+  char *t0[1] = {"tm0"};
+  char *t1[1] = {"tm1"};
+  char *sql = NULL;
+
+  ResultObj res = {1, {"tm1"}};
+  testQueryStr(schema, numOfCols, "a=1", pSkipList, &res);
+
+  char *tt[1] = {"tm6"};
+  setValue(&res, 1, tt);
+  testQueryStr(schema, numOfCols, "a>=6", pSkipList, &res);
+
+  setValue(&res, 1, t0);
+  testQueryStr(schema, numOfCols, "b<=10.6", pSkipList, &res);
+
+  strcpy(str, "c<>'pqr'");
+  char *t2[6] = {"tm0", "tm1", "tm2", "tm3", "tm4", "tm6"};
+  setValue(&res, 6, t2);
+  testQueryStr(schema, numOfCols, str, pSkipList, &res);
+
+  strcpy(str, "c='abc'");
+  setValue(&res, 1, t0);
+  testQueryStr(schema, numOfCols, str, pSkipList, &res);
+
+  char *t3[6] = {"tm1", "tm2", "tm3", "tm4", "tm5", "tm6"};
+  setValue(&res, 6, t3);
+  testQueryStr(schema, numOfCols, "d>1050", pSkipList, &res);
+
+  char *t4[3] = {"tm4", "tm5", "tm6"};
+  setValue(&res, 3, t4);
+  testQueryStr(schema, numOfCols, "g>4.5980765", pSkipList, &res);
+
+  char *t5[4] = {"tm0", "tm2", "tm4", "tm6"};
+  setValue(&res, 4, t5);
+  testQueryStr(schema, numOfCols, "h=true", pSkipList, &res);
+
+  char *t6[3] = {"tm1", "tm3", "tm5"};
+  setValue(&res, 3, t6);
+  testQueryStr(schema, numOfCols, "h=0", pSkipList, &res);
+
+  sql = "(((b<40)))\0";
+  char *t7[3] = {"tm0", "tm1", "tm2"};
+  setValue(&res, 3, t7);
+  testQueryStr(schema, numOfCols, sql, pSkipList, &res);
+
+  sql = "((a=1) or (a=10)) or ((b=12))";
+  setValue(&res, 1, t1);
+  testQueryStr(schema, numOfCols, sql, pSkipList, &res);
+
+  sql = "((((((a>0 and a<2))) or a=6) or a=3) or (b=50.5)) and h=0";
+  char *t8[2] = {"tm1", "tm3"};
+  setValue(&res, 2, t8);
+  testQueryStr(schema, numOfCols, sql, pSkipList, &res);
+
+  char *tf[1] = {"tm6"};
+  setValue(&res, 1, tf);
+  testQueryStr(schema, numOfCols, "e = -13000", pSkipList, &res);
+
+  char *ft[5] = {"tm0", "tm1", "tm2", "tm3", "tm4"};
+  setValue(&res, 5, ft);
+  testQueryStr(schema, numOfCols, "f > -65", pSkipList, &res);
+}
+
+void Right2LeftTest(SSchema *schema, int32_t numOfCols, tSkipList *pSkipList) {
+  ResultObj res = {1, {"tm1"}};
+  testQueryStr(schema, numOfCols, "((1=a))", pSkipList, &res);
+
+  char *t9[2] = {"tm0", "tm1"};
+  setValue(&res, 2, t9);
+  testQueryStr(schema, numOfCols, "1>=a", pSkipList, &res);
+
+  char *t0[1] = {"tm0"};
+  setValue(&res, 1, t0);
+  testQueryStr(schema, numOfCols, "10.6>=b", pSkipList, &res);
+
+  char *t10[3] = {"tm1", "tm3", "tm5"};
+  setValue(&res, 3, t10);
+  testQueryStr(schema, numOfCols, "0=h", pSkipList, &res);
+}
+
+static void IllegalExprTest(SSchema *schema, int32_t numOfCols, tSkipList *pSkipList) {
+  testQueryStr(schema, numOfCols, "h=", pSkipList, NULL);
+  testQueryStr(schema, numOfCols, "h<", pSkipList, NULL);
+  testQueryStr(schema, numOfCols, "a=1 and ", pSkipList, NULL);
+  testQueryStr(schema, numOfCols, "and or", pSkipList, NULL);
+  testQueryStr(schema, numOfCols, "and a = 1 or", pSkipList, NULL);
+  testQueryStr(schema, numOfCols, "(())", pSkipList, NULL);
+  testQueryStr(schema, numOfCols, "(", pSkipList, NULL);
+  testQueryStr(schema, numOfCols, "(a", pSkipList, NULL);
+  testQueryStr(schema, numOfCols, "(a)", pSkipList, NULL);
+  testQueryStr(schema, numOfCols, "())", pSkipList, NULL);
+  testQueryStr(schema, numOfCols, "a===1", pSkipList, NULL);
+  testQueryStr(schema, numOfCols, "a=1 and ", pSkipList, NULL);
+}
+
+static void Left2RightTest_binary(SSchema *schema, int32_t numOfCols, tSkipList *pSkipList) {
+  char  str[256] = {0};
+  char *sql = NULL;
+
+  char *t0[1] = {"tm0"};
+  char *t1[1] = {"tm1"};
+
+  ResultObj res = {1, {"tm0"}};
+  strcpy(str, "a='abc'");
+  testQueryStr(schema, numOfCols, str, pSkipList, &res);
+
+  char *tt[1] = {"tm6"};
+  setValue(&res, 1, tt);
+  testQueryStr(schema, numOfCols, "c>=6", pSkipList, &res);
+
+  setValue(&res, 1, t0);
+  testQueryStr(schema, numOfCols, "b<=10.6", pSkipList, &res);
+
+  strcpy(str, "a<>'pqr'");
+  char *t2[6] = {"tm0", "tm1", "tm2", "tm3", "tm4", "tm6"};
+  setValue(&res, 6, t2);
+  testQueryStr(schema, numOfCols, str, pSkipList, &res);
+
+  strcpy(str, "a='abc'");
+  setValue(&res, 1, t0);
+  testQueryStr(schema, numOfCols, str, pSkipList, &res);
+
+  char *t3[6] = {"tm1", "tm2", "tm3", "tm4", "tm5", "tm6"};
+  setValue(&res, 6, t3);
+  testQueryStr(schema, numOfCols, "d>1050", pSkipList, &res);
+
+  char *t4[3] = {"tm4", "tm5", "tm6"};
+  setValue(&res, 3, t4);
+  testQueryStr(schema, numOfCols, "g>4.5980765", pSkipList, &res);
+
+  char *t5[4] = {"tm0", "tm2", "tm4", "tm6"};
+  setValue(&res, 4, t5);
+  testQueryStr(schema, numOfCols, "h=true", pSkipList, &res);
+
+  char *t6[3] = {"tm1", "tm3", "tm5"};
+  setValue(&res, 3, t6);
+  testQueryStr(schema, numOfCols, "h=0", pSkipList, &res);
+
+  sql = "(((b<40)))\0";
+  char *t7[3] = {"tm0", "tm1", "tm2"};
+  setValue(&res, 3, t7);
+  testQueryStr(schema, numOfCols, sql, pSkipList, &res);
+
+  sql = "((c=1) or (c=10)) or ((b=12))\0";
+  setValue(&res, 1, t1);
+  testQueryStr(schema, numOfCols, sql, pSkipList, &res);
+
+  sql = "((((((c>0 and c<2))) or c=6) or c=3) or (b=50.5)) and h=false\0";
+  char *t8[2] = {"tm1", "tm3"};
+  setValue(&res, 2, t8);
+  testQueryStr(schema, numOfCols, sql, pSkipList, &res);
+}
+
+static void Right2LeftTest_binary(SSchema *schema, int32_t numOfCols, tSkipList *pSkipList) {
+  char  str[256] = {0};
+  char *sql = NULL;
+
+  char *t0[1] = {"tm0"};
+  char *t1[1] = {"tm1"};
+
+  ResultObj res = {1, {"tm0"}};
+  strcpy(str, "'abc'=a");
+  testQueryStr(schema, numOfCols, str, pSkipList, &res);
+
+  char *tt[1] = {"tm6"};
+  setValue(&res, 1, tt);
+  testQueryStr(schema, numOfCols, "6<=c", pSkipList, &res);
+
+  setValue(&res, 1, t0);
+  testQueryStr(schema, numOfCols, "10.6>=b", pSkipList, &res);
+
+  strcpy(str, "'pqr'<>a");
+  char *t2[6] = {"tm0", "tm1", "tm2", "tm3", "tm4", "tm6"};
+  setValue(&res, 6, t2);
+  testQueryStr(schema, numOfCols, str, pSkipList, &res);
+}
+
+namespace {
+// two level expression tree
+tExprNode *createExpr1() {
+  auto *pLeft = (tExprNode*) calloc(1, sizeof(tExprNode));
+  pLeft->nodeType = TSQL_NODE_COL;
+  pLeft->pSchema = (SSchema*) calloc(1, sizeof(SSchema));
+  
+  strcpy(pLeft->pSchema->name, "col_a");
+  pLeft->pSchema->type = TSDB_DATA_TYPE_INT;
+  pLeft->pSchema->bytes = sizeof(int32_t);
+  pLeft->pSchema->colId = 1;
+  
+  auto *pRight = (tExprNode*) calloc(1, sizeof(tExprNode));
+  pRight->nodeType = TSQL_NODE_VALUE;
+  pRight->pVal = (tVariant*) calloc(1, sizeof(tVariant));
+  
+  pRight->pVal->nType = TSDB_DATA_TYPE_INT;
+  pRight->pVal->i64Key = 12;
+  
+  auto *pRoot = (tExprNode*) calloc(1, sizeof(tExprNode));
+  pRoot->nodeType = TSQL_NODE_EXPR;
+  
+  pRoot->_node.optr = TSDB_RELATION_EQUAL;
+  pRoot->_node.pLeft = pLeft;
+  pRoot->_node.pRight = pRight;
+  pRoot->_node.hasPK = true;
+  
+  return pRoot;
+}
+
+// thress level expression tree
+tExprNode* createExpr2() {
+  auto *pLeft2 = (tExprNode*) calloc(1, sizeof(tExprNode));
+  pLeft2->nodeType = TSQL_NODE_COL;
+  pLeft2->pSchema = (SSchema*) calloc(1, sizeof(SSchema));
+  
+  strcpy(pLeft2->pSchema->name, "col_a");
+  pLeft2->pSchema->type = TSDB_DATA_TYPE_BINARY;
+  pLeft2->pSchema->bytes = 20;
+  pLeft2->pSchema->colId = 1;
+  
+  auto *pRight2 = (tExprNode*) calloc(1, sizeof(tExprNode));
+  pRight2->nodeType = TSQL_NODE_VALUE;
+  pRight2->pVal = (tVariant*) calloc(1, sizeof(tVariant));
+  
+  pRight2->pVal->nType = TSDB_DATA_TYPE_BINARY;
+  const char* v = "hello world!";
+  pRight2->pVal->pz = strdup(v);
+  pRight2->pVal->nLen = strlen(v);
+  
+  auto *p1 = (tExprNode*) calloc(1, sizeof(tExprNode));
+  p1->nodeType = TSQL_NODE_EXPR;
+  
+  p1->_node.optr = TSDB_RELATION_LIKE;
+  p1->_node.pLeft = pLeft2;
+  p1->_node.pRight = pRight2;
+  p1->_node.hasPK = false;
+  
+  auto *pLeft1 = (tExprNode*) calloc(1, sizeof(tExprNode));
+  pLeft1->nodeType = TSQL_NODE_COL;
+  pLeft1->pSchema = (SSchema*) calloc(1, sizeof(SSchema));
+  
+  strcpy(pLeft1->pSchema->name, "col_b");
+  pLeft1->pSchema->type = TSDB_DATA_TYPE_DOUBLE;
+  pLeft1->pSchema->bytes = 8;
+  pLeft1->pSchema->colId = 99;
+  
+  auto *pRight1 = (tExprNode*) calloc(1, sizeof(tExprNode));
+  pRight1->nodeType = TSQL_NODE_VALUE;
+  pRight1->pVal = (tVariant*) calloc(1, sizeof(tVariant));
+  
+  pRight1->pVal->nType = TSDB_DATA_TYPE_DOUBLE;
+  pRight1->pVal->dKey = 91.99;
+  
+  auto *p2 = (tExprNode*) calloc(1, sizeof(tExprNode));
+  p2->nodeType = TSQL_NODE_EXPR;
+  
+  p2->_node.optr = TSDB_RELATION_LARGE_EQUAL;
+  p2->_node.pLeft = pLeft1;
+  p2->_node.pRight = pRight1;
+  p2->_node.hasPK = false;
+  
+  auto *pRoot = (tExprNode*) calloc(1, sizeof(tExprNode));
+  pRoot->nodeType = TSQL_NODE_EXPR;
+  
+  pRoot->_node.optr = TSDB_RELATION_OR;
+  pRoot->_node.pLeft = p1;
+  pRoot->_node.pRight = p2;
+  pRoot->_node.hasPK = true;
+  return pRoot;
+}
+
+void exprSerializeTest1() {
+  tExprNode* p1 = createExpr1();
+  SBuffer buf = exprTreeToBinary(p1);
+  
+  size_t size = tbufTell(&buf);
+  ASSERT_TRUE(size > 0);
+  char* b = tbufGetData(&buf, false);
+  
+  tExprNode* p2 = exprTreeFromBinary(b, size);
+  ASSERT_EQ(p1->nodeType, p2->nodeType);
+  
+  ASSERT_EQ(p2->_node.optr, p1->_node.optr);
+  ASSERT_EQ(p2->_node.pLeft->nodeType, p1->_node.pLeft->nodeType);
+  ASSERT_EQ(p2->_node.pRight->nodeType, p1->_node.pRight->nodeType);
+  
+  SSchema* s1 = p1->_node.pLeft->pSchema;
+  SSchema* s2 = p2->_node.pLeft->pSchema;
+  
+  ASSERT_EQ(s2->colId, s1->colId);
+  ASSERT_EQ(s2->type, s1->type);
+  ASSERT_EQ(s2->bytes, s1->bytes);
+  ASSERT_STRCASEEQ(s2->name, s1->name);
+  
+  tVariant* v1 = p1->_node.pRight->pVal;
+  tVariant* v2 = p2->_node.pRight->pVal;
+  
+  ASSERT_EQ(v1->nType, v2->nType);
+  ASSERT_EQ(v1->i64Key, v2->i64Key);
+  ASSERT_EQ(p1->_node.hasPK, p2->_node.hasPK);
+  
+  tExprTreeDestroy(&p1, nullptr);
+  tExprTreeDestroy(&p2, nullptr);
+  
+  tbufClose(&buf, false);
+}
+
+void exprSerializeTest2() {
+  tExprNode* p1 = createExpr2();
+  SBuffer buf = exprTreeToBinary(p1);
+  
+  size_t size = tbufTell(&buf);
+  ASSERT_TRUE(size > 0);
+  char* b = tbufGetData(&buf, false);
+  
+  tExprNode* p2 = exprTreeFromBinary(b, size);
+  ASSERT_EQ(p1->nodeType, p2->nodeType);
+  
+  ASSERT_EQ(p2->_node.optr, p1->_node.optr);
+  ASSERT_EQ(p2->_node.pLeft->nodeType, p1->_node.pLeft->nodeType);
+  ASSERT_EQ(p2->_node.pRight->nodeType, p1->_node.pRight->nodeType);
+  
+  tExprNode* c1Left = p1->_node.pLeft;
+  tExprNode* c2Left = p2->_node.pLeft;
+  
+  ASSERT_EQ(c1Left->nodeType, c2Left->nodeType);
+  
+  ASSERT_EQ(c2Left->nodeType, TSQL_NODE_EXPR);
+  ASSERT_EQ(c2Left->_node.optr, TSDB_RELATION_LIKE);
+  
+  ASSERT_STRCASEEQ(c2Left->_node.pLeft->pSchema->name, "col_a");
+  ASSERT_EQ(c2Left->_node.pRight->nodeType, TSQL_NODE_VALUE);
+  
+  ASSERT_STRCASEEQ(c2Left->_node.pRight->pVal->pz, "hello world!");
+  
+  tExprNode* c1Right = p1->_node.pRight;
+  tExprNode* c2Right = p2->_node.pRight;
+  
+  ASSERT_EQ(c1Right->nodeType, c2Right->nodeType);
+  ASSERT_EQ(c2Right->nodeType, TSQL_NODE_EXPR);
+  ASSERT_EQ(c2Right->_node.optr, TSDB_RELATION_LARGE_EQUAL);
+  ASSERT_EQ(c2Right->_node.pRight->pVal->dKey, 91.99);
+  
+  ASSERT_EQ(p2->_node.hasPK, true);
+  
+  tExprTreeDestroy(&p1, nullptr);
+  tExprTreeDestroy(&p2, nullptr);
+
+  tbufClose(&buf, false);
+}
+}  // namespace
+TEST(testCase, astTest) {
+  exprSerializeTest2();
+}
\ No newline at end of file
diff --git a/src/util/inc/tbuffer.h b/src/util/inc/tbuffer.h
index 9dc6d97eb6..d52031fc6a 100644
--- a/src/util/inc/tbuffer.h
+++ b/src/util/inc/tbuffer.h
@@ -13,14 +13,15 @@
  * along with this program. If not, see <http://www.gnu.org/licenses/>.
  */
 
-#include <stddef.h>
-#include <stdint.h>
-#include <stdbool.h>
-#include <setjmp.h>
-
 #ifndef TDENGINE_TBUFFER_H
 #define TDENGINE_TBUFFER_H
 
+#include "setjmp.h"
+#include "os.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
 
 /*
 SBuffer can be used to read or write a buffer, but cannot be used for both
@@ -80,37 +81,33 @@ int main(int argc, char** argv) {
 */
 typedef struct {
   jmp_buf jb;
-  char* data;
-  size_t pos;
-  size_t size;
+  char*   data;
+  size_t  pos;
+  size_t  size;
 } SBuffer;
 
-
 // common functions can be used in both read & write
 #define tbufThrowError(buf, code) longjmp((buf)->jb, (code))
 size_t tbufTell(SBuffer* buf);
 size_t tbufSeekTo(SBuffer* buf, size_t pos);
 size_t tbufSkip(SBuffer* buf, size_t size);
-void tbufClose(SBuffer* buf, bool keepData);
-
+void   tbufClose(SBuffer* buf, bool keepData);
 
 // basic read functions
-#define tbufBeginRead(buf, data, len) (((buf)->data = (char*)data), ((buf)->pos = 0), ((buf)->size = ((data) == NULL) ? 0 : (len)), setjmp((buf)->jb))
-char* tbufRead(SBuffer* buf, size_t size);
-void tbufReadToBuffer(SBuffer* buf, void* dst, size_t size);
+#define tbufBeginRead(buf, _data, len) ((buf)->data = (char*)(_data), ((buf)->pos = 0), ((buf)->size = ((_data) == NULL) ? 0 : (len)), setjmp((buf)->jb))
+char*       tbufRead(SBuffer* buf, size_t size);
+void        tbufReadToBuffer(SBuffer* buf, void* dst, size_t size);
 const char* tbufReadString(SBuffer* buf, size_t* len);
-size_t tbufReadToString(SBuffer* buf, char* dst, size_t size);
-
+size_t      tbufReadToString(SBuffer* buf, char* dst, size_t size);
 
 // basic write functions
 #define tbufBeginWrite(buf) ((buf)->data = NULL, ((buf)->pos = 0), ((buf)->size = 0), setjmp((buf)->jb))
-void tbufEnsureCapacity(SBuffer* buf, size_t size);
+void  tbufEnsureCapacity(SBuffer* buf, size_t size);
 char* tbufGetData(SBuffer* buf, bool takeOver);
-void tbufWrite(SBuffer* buf, const void* data, size_t size);
-void tbufWriteAt(SBuffer* buf, size_t pos, const void* data, size_t size);
-void tbufWriteStringLen(SBuffer* buf, const char* str, size_t len);
-void tbufWriteString(SBuffer* buf, const char* str);
-
+void  tbufWrite(SBuffer* buf, const void* data, size_t size);
+void  tbufWriteAt(SBuffer* buf, size_t pos, const void* data, size_t size);
+void  tbufWriteStringLen(SBuffer* buf, const char* str, size_t len);
+void  tbufWriteString(SBuffer* buf, const char* str);
 
 // read & write function for primitive types
 #ifndef TBUFFER_DEFINE_FUNCTION
@@ -120,17 +117,21 @@ void tbufWriteString(SBuffer* buf, const char* str);
   void tbufWrite##name##At(SBuffer* buf, size_t pos, type data);
 #endif
 
-TBUFFER_DEFINE_FUNCTION( bool, Bool )
-TBUFFER_DEFINE_FUNCTION( char, Char )
-TBUFFER_DEFINE_FUNCTION( int8_t, Int8 )
-TBUFFER_DEFINE_FUNCTION( uint8_t, Unt8 )
-TBUFFER_DEFINE_FUNCTION( int16_t, Int16 )
-TBUFFER_DEFINE_FUNCTION( uint16_t, Uint16 )
-TBUFFER_DEFINE_FUNCTION( int32_t, Int32 )
-TBUFFER_DEFINE_FUNCTION( uint32_t, Uint32 )
-TBUFFER_DEFINE_FUNCTION( int64_t, Int64 )
-TBUFFER_DEFINE_FUNCTION( uint64_t, Uint64 )
-TBUFFER_DEFINE_FUNCTION( float, Float )
-TBUFFER_DEFINE_FUNCTION( double, Double )
+TBUFFER_DEFINE_FUNCTION(bool, Bool)
+TBUFFER_DEFINE_FUNCTION(char, Char)
+TBUFFER_DEFINE_FUNCTION(int8_t, Int8)
+TBUFFER_DEFINE_FUNCTION(uint8_t, Unt8)
+TBUFFER_DEFINE_FUNCTION(int16_t, Int16)
+TBUFFER_DEFINE_FUNCTION(uint16_t, Uint16)
+TBUFFER_DEFINE_FUNCTION(int32_t, Int32)
+TBUFFER_DEFINE_FUNCTION(uint32_t, Uint32)
+TBUFFER_DEFINE_FUNCTION(int64_t, Int64)
+TBUFFER_DEFINE_FUNCTION(uint64_t, Uint64)
+TBUFFER_DEFINE_FUNCTION(float, Float)
+TBUFFER_DEFINE_FUNCTION(double, Double)
+
+#ifdef __cplusplus
+}
+#endif
 
 #endif
\ No newline at end of file
diff --git a/src/util/src/tbuffer.c b/src/util/src/tbuffer.c
index ac7d22078d..a83d7dddb0 100644
--- a/src/util/src/tbuffer.c
+++ b/src/util/src/tbuffer.c
@@ -30,7 +30,7 @@
     tbufWriteAt(buf, pos, &data, sizeof(data));\
   }
 
-#include "../inc/tbuffer.h"
+#include "tbuffer.h"
 
 
 ////////////////////////////////////////////////////////////////////////////////
@@ -119,13 +119,14 @@ void tbufEnsureCapacity(SBuffer* buf, size_t size) {
 }
 
 char* tbufGetData(SBuffer* buf, bool takeOver) {
-		char* ret = buf->data;
-		if (takeOver) {
-      buf->pos = 0;
-      buf->size = 0;
-			buf->data = NULL;
-    }
-		return ret;
+  char* ret = buf->data;
+  if (takeOver) {
+    buf->pos = 0;
+    buf->size = 0;
+    buf->data = NULL;
+  }
+
+  return ret;
 }
 
 void tbufEndWrite(SBuffer* buf) {
diff --git a/src/vnode/tsdb/src/tsdbFile.c b/src/vnode/tsdb/src/tsdbFile.c
index ff8da1cdad..bd6699eb84 100644
--- a/src/vnode/tsdb/src/tsdbFile.c
+++ b/src/vnode/tsdb/src/tsdbFile.c
@@ -147,6 +147,11 @@ void tsdbInitFileGroupIter(STsdbFileH *pFileH, SFileGroupIter *pIter, int direct
 }
 
 void tsdbSeekFileGroupIter(SFileGroupIter *pIter, int fid) {
+  if (pIter->numOfFGroups == 0) {
+    assert(pIter->pFileGroup == NULL);
+    return;
+  }
+  
   int flags = (pIter->direction == TSDB_FGROUP_ITER_FORWARD) ? TD_GE : TD_LE;
   void *ptr = taosbsearch(&fid, pIter->base, sizeof(SFileGroup), pIter->numOfFGroups, compFGroupKey, flags);
   if (ptr == NULL) {
diff --git a/src/vnode/tsdb/src/tsdbRead.c b/src/vnode/tsdb/src/tsdbRead.c
index 5635d9a98f..599d8bd347 100644
--- a/src/vnode/tsdb/src/tsdbRead.c
+++ b/src/vnode/tsdb/src/tsdbRead.c
@@ -424,6 +424,28 @@ static SDataBlockInfo getTrueDataBlockInfo(STsdbQueryHandle* pHandle, STableChec
 SArray *getDefaultLoadColumns(STsdbQueryHandle *pQueryHandle, bool loadTS);
 static void filterDataInDataBlock(STsdbQueryHandle *pQueryHandle, SDataCols* pCols, SArray *sa);
 
+static bool doLoadDataFromFileBlock(STsdbQueryHandle *pQueryHandle) {
+  SQueryFilePos *cur = &pQueryHandle->cur;
+  
+  STableCheckInfo* pCheckInfo = taosArrayGet(pQueryHandle->pTableCheckInfo, pQueryHandle->activeIndex);
+  SCompBlock* pBlock = &pCheckInfo->pCompInfo->blocks[cur->slot];
+  
+  SCompData* data = calloc(1, sizeof(SCompData)+ sizeof(SCompCol)*pBlock->numOfCols);
+  
+  data->numOfCols = pBlock->numOfCols;
+  data->uid = pCheckInfo->pTableObj->tableId.uid;
+  
+  pCheckInfo->pDataCols = tdNewDataCols(1000, 2, 4096);
+  tdInitDataCols(pCheckInfo->pDataCols, pCheckInfo->pTableObj->schema);
+  
+  SFile* pFile = &pCheckInfo->pFileGroup->files[TSDB_FILE_TYPE_DATA];
+  if (pFile->fd == FD_INITIALIZER) {
+    pFile->fd = open(pFile->fname, O_RDONLY);
+  }
+  
+  tsdbLoadDataBlock(pFile, pBlock, 1, pCheckInfo->pDataCols, data);
+}
+
 static bool loadQualifiedDataFromFileBlock(STsdbQueryHandle *pQueryHandle) {
   SQueryFilePos *cur = &pQueryHandle->cur;
   
@@ -432,31 +454,18 @@ static bool loadQualifiedDataFromFileBlock(STsdbQueryHandle *pQueryHandle) {
   
   SArray *sa = getDefaultLoadColumns(pQueryHandle, true);
   if (QUERY_IS_ASC_QUERY(pQueryHandle->order)) {
+    
+    // query ended in current block
     if (pQueryHandle->window.ekey < pBlock->keyLast) {
-      SCompData*  data = calloc(1, sizeof(SCompData)+ sizeof(SCompCol)*pBlock->numOfCols);
-  
-      data->numOfCols = pBlock->numOfCols;
-      data->uid = pCheckInfo->pTableObj->tableId.uid;
-  
-      pCheckInfo->pDataCols = tdNewDataCols(1000, 2, 4096);
-      tdInitDataCols(pCheckInfo->pDataCols, pCheckInfo->pTableObj->schema);
-  
-      SFile* pFile = &pCheckInfo->pFileGroup->files[TSDB_FILE_TYPE_DATA];
-      if (pFile->fd == FD_INITIALIZER) {
-        pFile->fd = open(pFile->fname, O_RDONLY);
-      }
-  
-      if (tsdbLoadDataBlock(pFile, pBlock, 1, pCheckInfo->pDataCols, data) == 0) {
-        //do something
-      }
+      doLoadDataFromFileBlock(pQueryHandle);
+      filterDataInDataBlock(pQueryHandle, pCheckInfo->pDataCols, sa);
     }
-  } else {
+  } else {// todo desc query
     if (pQueryHandle->window.ekey > pBlock->keyFirst) {
-//      loadDataBlockIntoMem_(pQueryHandle, pBlock, &pQueryHandle->pFields[cur->slot], cur->fileId, sa);
+//
     }
   }
   
-  filterDataInDataBlock(pQueryHandle, pCheckInfo->pDataCols, sa);
   return pQueryHandle->realNumOfRows > 0;
 }
 
@@ -508,7 +517,7 @@ bool moveToNextBlock(STsdbQueryHandle *pQueryHandle, int32_t step) {
       // next block in the same file
       cur->slot += step;
 
-      SCompBlock* pBlock = &pQueryHandle->pBlock[cur->slot];
+      SCompBlock* pBlock = &pCheckInfo->pCompInfo->blocks[cur->slot];
       cur->pos = (step == QUERY_ASC_FORWARD_STEP) ? 0 : pBlock->numOfPoints - 1;
       return loadQualifiedDataFromFileBlock(pQueryHandle);
     }
@@ -736,12 +745,23 @@ static bool getQualifiedDataBlock(STsdbQueryHandle *pQueryHandle, STableCheckInf
   int32_t index = -1;
 
   int32_t tid = pCheckInfo->tableId.tid;
-  SFile* pFile = &pCheckInfo->pFileGroup->files[TSDB_FILE_TYPE_DATA];
   
-  while (1) {
+  while (pCheckInfo->pFileGroup != NULL) {
     if ((fid = getFileCompInfo(pCheckInfo, pCheckInfo->pFileGroup)) < 0) {
       break;
     }
+  
+    SFile* pFile = &pCheckInfo->pFileGroup->files[TSDB_FILE_TYPE_DATA];
+  
+    // no data block in current file, try next
+    if (pCheckInfo->compIndex[tid].numOfSuperBlocks == 0) {
+      dTrace("QInfo:%p no data block in file, fid:%d, tid:%d, try next", pQueryHandle->qinfo,
+          pCheckInfo->pFileGroup->fileId, tid);
+      
+      pCheckInfo->pFileGroup = tsdbGetFileGroupNext(&pCheckInfo->fileIter);
+  
+      continue;
+    }
     
     index = binarySearchForBlockImpl(pCheckInfo->pCompInfo->blocks, pCheckInfo->compIndex[tid].numOfSuperBlocks, pQueryHandle->order, key);
     
@@ -769,12 +789,11 @@ static bool getQualifiedDataBlock(STsdbQueryHandle *pQueryHandle, STableCheckInf
   
   // load first data block into memory failed, caused by disk block error
   bool    blockLoaded = false;
-  SArray *sa = NULL;
+  SArray *sa = getDefaultLoadColumns(pQueryHandle, true);
   
   // todo no need to loaded at all
   cur->slot = index;
   
-  sa = getDefaultLoadColumns(pQueryHandle, true);
   SCompBlock* pBlock = &pCheckInfo->pCompInfo->blocks[cur->slot];
   SCompData*  data = calloc(1, sizeof(SCompData)+ sizeof(SCompCol)*pBlock->numOfCols);
   
@@ -784,6 +803,7 @@ static bool getQualifiedDataBlock(STsdbQueryHandle *pQueryHandle, STableCheckInf
   pCheckInfo->pDataCols = tdNewDataCols(1000, 2, 4096);
   tdInitDataCols(pCheckInfo->pDataCols, pCheckInfo->pTableObj->schema);
   
+  SFile* pFile = &pCheckInfo->pFileGroup->files[TSDB_FILE_TYPE_DATA];
   if (pFile->fd == FD_INITIALIZER) {
     pFile->fd = open(pFile->fname, O_RDONLY);
   }
@@ -973,11 +993,16 @@ SArray *tsdbRetrieveDataBlock(tsdb_query_handle_t *pQueryHandle, SArray *pIdList
     STableCheckInfo* pCheckInfo = taosArrayGet(pHandle->pTableCheckInfo, pHandle->activeIndex);
     
     SDataBlockInfo binfo = getTrueDataBlockInfo(pHandle, pCheckInfo);
-    if (pHandle->realNumOfRows <= binfo.size) {
+    assert(pHandle->realNumOfRows <= binfo.size);
+    
+    if (pHandle->realNumOfRows < binfo.size) {
       return pHandle->pColumns;
     } else {
-      // todo do load data block
-      assert(0);
+      SArray *sa = getDefaultLoadColumns(pHandle, true);
+  
+      doLoadDataFromFileBlock(pHandle);
+      filterDataInDataBlock(pHandle, pCheckInfo->pDataCols, sa);
+      return pHandle->pColumns;
     }
   }
 }
@@ -1197,7 +1222,7 @@ static void getTagColumnInfo(SSyntaxTreeFilterSupporter* pSupporter, SSchema* pS
 }
 
 void filterPrepare(void* expr, void* param) {
-  tSQLSyntaxNode *pExpr = (tSQLSyntaxNode*) expr;
+  tExprNode *pExpr = (tExprNode*) expr;
   if (pExpr->_node.info != NULL) {
     return;
   }
@@ -1276,7 +1301,7 @@ bool tSkipListNodeFilterCallback(const void* pNode, void* param) {
 static int32_t doQueryTableList(STable* pSTable, SArray* pRes, const char* pCond) {
   STColumn* stcol = schemaColAt(pSTable->tagSchema, 0);
   
-  tSQLSyntaxNode* pExpr = NULL;
+  tExprNode* pExpr = NULL;
   tSQLBinaryExprFromString(&pExpr, stcol, schemaNCols(pSTable->tagSchema), pCond, strlen(pCond));
   
   // failed to build expression, no result, return immediately
@@ -1297,7 +1322,7 @@ static int32_t doQueryTableList(STable* pSTable, SArray* pRes, const char* pCond
   };
   
   tSQLBinaryExprTraverse(pExpr, pSTable->pIndex, pRes, &supp);
-  tSQLBinaryExprDestroy(&pExpr, tSQLListTraverseDestroyInfo);
+  tExprTreeDestroy(&pExpr, tSQLListTraverseDestroyInfo);
   
   tansformQueryResult(pRes);