diff --git a/.gitignore b/.gitignore
index f2c1cb75b3..e91d6739a5 100644
--- a/.gitignore
+++ b/.gitignore
@@ -19,7 +19,6 @@ tests/test/
 tests/taoshebei/
 tests/taoscsv/
 tests/taosdalipu/
-tests/pytest/
 tests/jenkins/
 tests/hdfs/
 *.iml
diff --git a/.travis.yml b/.travis.yml
index 63c62d1a8a..221a1f1a30 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -14,6 +14,15 @@ os:
   - linux
 #  - osx
 
+before_install:
+  - |-
+    case $TRAVIS_OS_NAME in
+      linux)
+        sudo apt -y update
+        sudo apt -y install python-pip python3-pip python-setuptools python3-setuptools
+        ;;
+    esac
+
 addons:
   coverity_scan:
 
@@ -50,6 +59,15 @@ script:
   - |-
     case $TRAVIS_OS_NAME in
       linux)
+        # Color setting
+        RED='\033[0;31m'
+        GREEN='\033[1;32m'
+        GREEN_DARK='\033[0;32m'
+        GREEN_UNDERLINE='\033[4;32m'
+        NC='\033[0m'
+
+        sudo make install
+
         cd ../tests/script
         sudo ./test.sh 2>&1 | grep 'success\|failed' | tee out.txt
 
@@ -57,16 +75,32 @@ script:
 
         if [ "$total_success" -gt "0" ]; then
           total_success=`expr $total_success - 1`
+          echo -e "${GREEN} ### Total $total_success TSIM case(s) succeed! ### ${NC}"
         fi
 
-        echo "Total $total_success success"
-
         total_failed=`grep failed out.txt | wc -l`
-        echo "Total $total_failed failed"
-
         if [ "$total_failed" -ne "0" ]; then
+          echo -e "${RED} ### Total $total_failed TSIM case(s) failed! ### ${NC}"
           exit $total_failed
         fi
+
+        pip install --user ../../src/connector/python/linux/python2/ 
+        pip3 install --user ../../src/connector/python/linux/python3/ 
+
+        cd ../pytest
+        sudo ./simpletest.sh 2>&1 | grep 'successfully executed\|failed' | tee pytest-out.txt
+        total_py_success=`grep 'successfully executed' pytest-out.txt | wc -l`
+
+        if [ "$total_py_success" -gt "0" ]; then
+          echo -e "${GREEN} ### Total $total_py_success python case(s) succeed! ### ${NC}"
+        fi
+
+        total_py_failed=`grep 'failed' pytest-out.txt | wc -l`
+        if [ "$total_py_failed" -ne "0" ]; then
+          echo -e "${RED} ### Total $total_py_failed python case(s) failed! ### ${NC}"
+          exit $total_py_failed
+        fi
+
         ;;
     esac
 
@@ -81,6 +115,10 @@ matrix:
           - build-essential
           - cmake
           - net-tools
+          - python-pip
+          - python-setuptools
+          - python3-pip
+          - python3-setuptools
 
 #  - os: osx
 #    addons:
diff --git a/src/client/src/tscSql.c b/src/client/src/tscSql.c
index 1eee5d5e7f..41cfb77c5d 100644
--- a/src/client/src/tscSql.c
+++ b/src/client/src/tscSql.c
@@ -698,6 +698,7 @@ TAOS_ROW taos_fetch_row(TAOS_RES *res) {
 }
 
 int taos_fetch_block(TAOS_RES *res, TAOS_ROW *rows) {
+#if 0
   SSqlObj *pSql = (SSqlObj *)res;
   SSqlCmd *pCmd = &pSql->cmd;
   SSqlRes *pRes = &pSql->res;
@@ -737,6 +738,10 @@ int taos_fetch_block(TAOS_RES *res, TAOS_ROW *rows) {
   }
 
   return nRows;
+#endif
+
+  (*rows) = taos_fetch_row(res);
+  return ((*rows) != NULL)? 1:0;
 }
 
 int taos_select_db(TAOS *taos, const char *db) {
diff --git a/src/dnode/src/dnodeRead.c b/src/dnode/src/dnodeRead.c
index d4365dae10..f13c18f22a 100644
--- a/src/dnode/src/dnodeRead.c
+++ b/src/dnode/src/dnodeRead.c
@@ -32,27 +32,51 @@ typedef struct {
   SRpcMsg  rpcMsg;
 } SReadMsg;
 
+typedef struct {
+  pthread_t  thread;    // thread 
+  int32_t    workerId;  // worker ID
+} SReadWorker;
+
+typedef struct {
+  int32_t    max;       // max number of workers
+  int32_t    min;       // min number of workers
+  int32_t    num;       // current number of workers
+  SReadWorker *readWorker;
+} SReadWorkerPool;
+
 static void *dnodeProcessReadQueue(void *param);
-static void  dnodeHandleIdleReadWorker();
+static void  dnodeHandleIdleReadWorker(SReadWorker *);
 
 // module global variable
-static taos_qset readQset;
-static int32_t   threads;    // number of query threads
-static int32_t   maxThreads;
-static int32_t   minThreads;
+static SReadWorkerPool readPool;
+static taos_qset       readQset;
 
 int32_t dnodeInitRead() {
   readQset = taosOpenQset();
 
-  minThreads = 3;
-  maxThreads = tsNumOfCores * tsNumOfThreadsPerCore;
-  if (maxThreads <= minThreads * 2) maxThreads = 2 * minThreads;
+  readPool.min = 2;
+  readPool.max = tsNumOfCores * tsNumOfThreadsPerCore;
+  if (readPool.max <= readPool.min * 2) readPool.max = 2 * readPool.min;
+  readPool.readWorker = (SReadWorker *) calloc(sizeof(SReadWorker), readPool.max);
+
+  if (readPool.readWorker == NULL) return -1;
+  for (int i=0; i < readPool.max; ++i) {
+    SReadWorker *pWorker = readPool.readWorker + i;
+    pWorker->workerId = i;
+  }
 
   dPrint("dnode read is opened");
   return 0;
 }
 
 void dnodeCleanupRead() {
+
+  for (int i=0; i < readPool.max; ++i) {
+    SReadWorker *pWorker = readPool.readWorker + i;
+    if (pWorker->thread) 
+      pthread_join(pWorker->thread, NULL);
+  }
+
   taosCloseQset(readQset);
   dPrint("dnode read is closed");
 }
@@ -116,18 +140,25 @@ void *dnodeAllocateRqueue(void *pVnode) {
   taosAddIntoQset(readQset, queue, pVnode);
 
   // spawn a thread to process queue
-  if (threads < maxThreads) {
-    pthread_t thread;
-    pthread_attr_t thAttr;
-    pthread_attr_init(&thAttr);
-    pthread_attr_setdetachstate(&thAttr, PTHREAD_CREATE_JOINABLE);
+  if (readPool.num < readPool.max) {
+    do {
+      SReadWorker *pWorker = readPool.readWorker + readPool.num;
 
-    if (pthread_create(&thread, &thAttr, dnodeProcessReadQueue, readQset) != 0) {
-      dError("failed to create thread to process read queue, reason:%s", strerror(errno));
-    }
+      pthread_attr_t thAttr;
+      pthread_attr_init(&thAttr);
+      pthread_attr_setdetachstate(&thAttr, PTHREAD_CREATE_JOINABLE);
+
+      if (pthread_create(&pWorker->thread, &thAttr, dnodeProcessReadQueue, pWorker) != 0) {
+        dError("failed to create thread to process read queue, reason:%s", strerror(errno));
+      }
+
+      pthread_attr_destroy(&thAttr);
+      readPool.num++;
+      dTrace("read worker:%d is launched, total:%d", pWorker->workerId, readPool.num);
+    } while (readPool.num < readPool.min);
   }
 
-  dTrace("pVnode:%p, queue:%p is allocated", pVnode, queue); 
+  dTrace("pVnode:%p, read queue:%p is allocated", pVnode, queue); 
 
   return queue;
 }
@@ -167,14 +198,14 @@ void dnodeSendRpcReadRsp(void *pVnode, SReadMsg *pRead, int32_t code) {
 }
 
 static void *dnodeProcessReadQueue(void *param) {
-  taos_qset  qset = (taos_qset)param;
-  SReadMsg  *pReadMsg;
-  int        type;
-  void      *pVnode;
+  SReadWorker *pWorker = param;
+  SReadMsg    *pReadMsg;
+  int          type;
+  void        *pVnode;
 
   while (1) {
-    if (taosReadQitemFromQset(qset, &type, (void **)&pReadMsg, (void **)&pVnode) == 0) {
-      dnodeHandleIdleReadWorker();
+    if (taosReadQitemFromQset(readQset, &type, (void **)&pReadMsg, &pVnode) == 0) {
+      dnodeHandleIdleReadWorker(pWorker);
       continue;
     }
 
@@ -186,11 +217,12 @@ static void *dnodeProcessReadQueue(void *param) {
   return NULL;
 }
 
-static void dnodeHandleIdleReadWorker() {
+static void dnodeHandleIdleReadWorker(SReadWorker *pWorker) {
   int32_t num = taosGetQueueNumber(readQset);
 
-  if (num == 0 || (num <= minThreads && threads > minThreads)) {
-    threads--;
+  if (num == 0 || (num <= readPool.min && readPool.num > readPool.min)) {
+    readPool.num--;
+    dTrace("read worker:%d is released, total:%d", pWorker->workerId, readPool.num);
     pthread_exit(NULL);
   } else {
     usleep(100);
diff --git a/src/dnode/src/dnodeWrite.c b/src/dnode/src/dnodeWrite.c
index 3c598ca360..b56e0d8ad7 100644
--- a/src/dnode/src/dnodeWrite.c
+++ b/src/dnode/src/dnodeWrite.c
@@ -28,6 +28,7 @@
 #include "vnode.h"
 
 typedef struct {
+  taos_qall  qall;
   taos_qset  qset;      // queue set
   pthread_t  thread;    // thread 
   int32_t    workerId;  // worker ID
@@ -65,6 +66,14 @@ int32_t dnodeInitWrite() {
 }
 
 void dnodeCleanupWrite() {
+  
+  for (int32_t i = 0; i < wWorkerPool.max; ++i) {
+    SWriteWorker *pWorker =  wWorkerPool.writeWorker + i;
+    if (pWorker->thread) {
+      pthread_join(pWorker->thread, NULL);
+    }
+  }
+
   free(wWorkerPool.writeWorker);
   dPrint("dnode write is closed");
 }
@@ -113,6 +122,7 @@ void *dnodeAllocateWqueue(void *pVnode) {
     if (pWorker->qset == NULL) return NULL;
 
     taosAddIntoQset(pWorker->qset, queue, pVnode);
+    pWorker->qall = taosAllocateQall();
     wWorkerPool.nextId = (wWorkerPool.nextId + 1) % wWorkerPool.max;
 
     pthread_attr_t thAttr;
@@ -122,13 +132,17 @@ void *dnodeAllocateWqueue(void *pVnode) {
     if (pthread_create(&pWorker->thread, &thAttr, dnodeProcessWriteQueue, pWorker) != 0) {
       dError("failed to create thread to process read queue, reason:%s", strerror(errno));
       taosCloseQset(pWorker->qset);
+    } else {
+      dTrace("write worker:%d is launched", pWorker->workerId);
     }
+
+    pthread_attr_destroy(&thAttr);
   } else {
     taosAddIntoQset(pWorker->qset, queue, pVnode);
     wWorkerPool.nextId = (wWorkerPool.nextId + 1) % wWorkerPool.max;
   }
 
-  dTrace("pVnode:%p, queue:%p is allocated", pVnode, queue);
+  dTrace("pVnode:%p, write queue:%p is allocated", pVnode, queue);
 
   return queue;
 }
@@ -160,17 +174,14 @@ void dnodeSendRpcWriteRsp(void *pVnode, void *param, int32_t code) {
 
 static void *dnodeProcessWriteQueue(void *param) {
   SWriteWorker *pWorker = (SWriteWorker *)param;
-  taos_qall     qall;
   SWriteMsg    *pWrite;
   SWalHead     *pHead;
   int32_t       numOfMsgs;
   int           type;
   void         *pVnode, *item;
 
-  qall = taosAllocateQall();
-
   while (1) {
-    numOfMsgs = taosReadAllQitemsFromQset(pWorker->qset, qall, &pVnode);
+    numOfMsgs = taosReadAllQitemsFromQset(pWorker->qset, pWorker->qall, &pVnode);
     if (numOfMsgs <=0) { 
       dnodeHandleIdleWorker(pWorker);  // thread exit if no queues anymore
       continue;
@@ -178,7 +189,7 @@ static void *dnodeProcessWriteQueue(void *param) {
 
     for (int32_t i = 0; i < numOfMsgs; ++i) {
       pWrite = NULL;
-      taosGetQitem(qall, &type, &item);
+      taosGetQitem(pWorker->qall, &type, &item);
       if (type == TAOS_QTYPE_RPC) {
         pWrite = (SWriteMsg *)item;
         pHead = (SWalHead *)(pWrite->pCont - sizeof(SWalHead));
@@ -196,9 +207,9 @@ static void *dnodeProcessWriteQueue(void *param) {
     walFsync(vnodeGetWal(pVnode));
 
     // browse all items, and process them one by one
-    taosResetQitems(qall);
+    taosResetQitems(pWorker->qall);
     for (int32_t i = 0; i < numOfMsgs; ++i) {
-      taosGetQitem(qall, &type, &item);
+      taosGetQitem(pWorker->qall, &type, &item);
       if (type == TAOS_QTYPE_RPC) {
         pWrite = (SWriteMsg *)item;
         dnodeSendRpcWriteRsp(pVnode, item, pWrite->rpcMsg.code); 
@@ -209,8 +220,6 @@ static void *dnodeProcessWriteQueue(void *param) {
     }
   }
 
-  taosFreeQall(qall);
-
   return NULL;
 }
 
@@ -221,8 +230,10 @@ static void dnodeHandleIdleWorker(SWriteWorker *pWorker) {
      usleep(1000);
      sched_yield(); 
   } else {
+     taosFreeQall(pWorker->qall);
      taosCloseQset(pWorker->qset);
      pWorker->qset = NULL;
+     dTrace("write worker:%d is released", pWorker->workerId);
      pthread_exit(NULL);
   }
 }
diff --git a/src/kit/shell/src/shellEngine.c b/src/kit/shell/src/shellEngine.c
index 0325e7f641..e291fdc551 100644
--- a/src/kit/shell/src/shellEngine.c
+++ b/src/kit/shell/src/shellEngine.c
@@ -284,7 +284,7 @@ void shellRunCommandOnServer(TAOS *con, char command[]) {
 /* Function to do regular expression check */
 int regex_match(const char *s, const char *reg, int cflags) {
   regex_t regex;
-  char    msgbuf[100];
+  char    msgbuf[100] = {0};
 
   /* Compile regular expression */
   if (regcomp(&regex, reg, cflags) != 0) {
diff --git a/src/kit/shell/src/shellMain.c b/src/kit/shell/src/shellMain.c
index a7b7e8383b..81a41453e8 100644
--- a/src/kit/shell/src/shellMain.c
+++ b/src/kit/shell/src/shellMain.c
@@ -97,6 +97,8 @@ int main(int argc, char* argv[]) {
 
   /* Interupt handler. */
   struct sigaction act;
+  memset(&act, 0, sizeof(struct sigaction));
+  
   act.sa_handler = interruptHandler;
   sigaction(SIGTERM, &act, NULL);
   sigaction(SIGINT, &act, NULL);
diff --git a/src/rpc/src/rpcCache.c b/src/rpc/src/rpcCache.c
index a397f6f845..a4863ef61d 100644
--- a/src/rpc/src/rpcCache.c
+++ b/src/rpc/src/rpcCache.c
@@ -103,7 +103,8 @@ void rpcCloseConnCache(void *handle) {
   if (pCache->connHashMemPool) taosMemPoolCleanUp(pCache->connHashMemPool);
 
   tfree(pCache->connHashList);
-  tfree(pCache->count)
+  tfree(pCache->count);
+  tfree(pCache->lockedBy);
 
   pthread_mutex_unlock(&pCache->mutex);
 
diff --git a/src/rpc/src/rpcClient.c b/src/rpc/src/rpcClient.c
index b362b1ba44..264449bbb0 100644
--- a/src/rpc/src/rpcClient.c
+++ b/src/rpc/src/rpcClient.c
@@ -84,7 +84,9 @@ void *taosInitTcpClient(char *ip, uint16_t port, char *label, int num, void *fp,
 
   pthread_attr_init(&thattr);
   pthread_attr_setdetachstate(&thattr, PTHREAD_CREATE_JOINABLE);
-  if (pthread_create(&(pTcp->thread), &thattr, taosReadTcpData, (void *)(pTcp)) != 0) {
+  int code = pthread_create(&(pTcp->thread), &thattr, taosReadTcpData, (void *)(pTcp));
+  pthread_attr_destroy(&thattr);
+  if (code != 0) {
     tError("%s failed to create TCP read data thread, reason:%s", label, strerror(errno));
     return NULL;
   }
diff --git a/src/rpc/src/rpcServer.c b/src/rpc/src/rpcServer.c
index 1aadabc5f7..538b3059e3 100644
--- a/src/rpc/src/rpcServer.c
+++ b/src/rpc/src/rpcServer.c
@@ -83,6 +83,9 @@ void *taosInitTcpServer(char *ip, uint16_t port, char *label, int numOfThreads,
   }
   memset(pServerObj->pThreadObj, 0, sizeof(SThreadObj) * (size_t)numOfThreads);
 
+  pthread_attr_init(&thattr);
+  pthread_attr_setdetachstate(&thattr, PTHREAD_CREATE_JOINABLE);
+
   pThreadObj = pServerObj->pThreadObj;
   for (i = 0; i < numOfThreads; ++i) {
     pThreadObj->processData = fp;
@@ -105,8 +108,6 @@ void *taosInitTcpServer(char *ip, uint16_t port, char *label, int numOfThreads,
       return NULL;
     }
 
-    pthread_attr_init(&thattr);
-    pthread_attr_setdetachstate(&thattr, PTHREAD_CREATE_JOINABLE);
     if (pthread_create(&(pThreadObj->thread), &thattr, (void *)taosProcessTcpData, (void *)(pThreadObj)) != 0) {
       tError("%s failed to create TCP process data thread, reason:%s", label, strerror(errno));
       return NULL;
@@ -116,8 +117,6 @@ void *taosInitTcpServer(char *ip, uint16_t port, char *label, int numOfThreads,
     pThreadObj++;
   }
 
-  pthread_attr_init(&thattr);
-  pthread_attr_setdetachstate(&thattr, PTHREAD_CREATE_JOINABLE);
   if (pthread_create(&(pServerObj->thread), &thattr, (void *)taosAcceptTcpConnection, (void *)(pServerObj)) != 0) {
     tError("%s failed to create TCP accept thread, reason:%s", label, strerror(errno));
     return NULL;
diff --git a/src/rpc/src/rpcUdp.c b/src/rpc/src/rpcUdp.c
index 64a4df0e73..785288f5b9 100644
--- a/src/rpc/src/rpcUdp.c
+++ b/src/rpc/src/rpcUdp.c
@@ -146,10 +146,12 @@ void *taosInitUdpConnection(char *ip, uint16_t port, char *label, int threads, v
       pConn->tmrCtrl = pSet->tmrCtrl;
     }
 
-    if (pthread_create(&pConn->thread, &thAttr, taosRecvUdpData, pConn) != 0) {
+    int code = pthread_create(&pConn->thread, &thAttr, taosRecvUdpData, pConn);
+    if (code != 0) {
       tError("%s failed to create thread to process UDP data, reason:%s", label, strerror(errno));
       taosCloseSocket(pConn->fd);
       taosCleanUpUdpConnection(pSet);
+      pthread_attr_destroy(&thAttr);
       return NULL;
     }
 
diff --git a/src/util/src/hash.c b/src/util/src/hash.c
index 9cad14e8c7..03e155845e 100644
--- a/src/util/src/hash.c
+++ b/src/util/src/hash.c
@@ -298,7 +298,7 @@ SHashObj *taosHashInit(size_t capacity, _hash_fn_t fn, bool threadsafe) {
  */
 static SHashNode *doCreateHashNode(const char *key, size_t keyLen, const char *pData, size_t dataSize,
                                    uint32_t hashVal) {
-  size_t totalSize = dataSize + sizeof(SHashNode) + keyLen;
+  size_t totalSize = dataSize + sizeof(SHashNode) + keyLen + 1;  // one extra byte for null
 
   SHashNode *pNewNode = calloc(1, totalSize);
   if (pNewNode == NULL) {
diff --git a/src/util/src/ihash.c b/src/util/src/ihash.c
index 30773ae8d9..2cfadad964 100644
--- a/src/util/src/ihash.c
+++ b/src/util/src/ihash.c
@@ -189,7 +189,6 @@ void taosCleanUpIntHash(void *handle) {
     free(pObj->hashList);
   }
 
-  memset(pObj, 0, sizeof(IHashObj));
   free(pObj->lockedBy);
   free(pObj);
 }
diff --git a/src/util/src/tqueue.c b/src/util/src/tqueue.c
index 2cf94267f8..b9f1141d35 100644
--- a/src/util/src/tqueue.c
+++ b/src/util/src/tqueue.c
@@ -117,7 +117,7 @@ int taosWriteQitem(taos_queue param, int type, void *item) {
   queue->numOfItems++;
   if (queue->qset) atomic_add_fetch_32(&queue->qset->numOfItems, 1);
 
-  pTrace("item:%p is put into queue, type:%d items:%d", item, type, queue->numOfItems);
+  pTrace("item:%p is put into queue:%p, type:%d items:%d", item, queue, type, queue->numOfItems);
 
   pthread_mutex_unlock(&queue->mutex);
 
@@ -297,14 +297,16 @@ int taosReadQitemFromQset(taos_qset param, int *type, void **pitem, void **phand
   STaosQset  *qset = (STaosQset *)param;
   STaosQnode *pNode = NULL;
   int         code = 0;
+   
+  pthread_mutex_lock(&qset->mutex);
 
   for(int i=0; i<qset->numOfQueues; ++i) {
-    pthread_mutex_lock(&qset->mutex);
+    //pthread_mutex_lock(&qset->mutex);
     if (qset->current == NULL) 
       qset->current = qset->head;   
     STaosQueue *queue = qset->current;
     if (queue) qset->current = queue->next;
-    pthread_mutex_unlock(&qset->mutex);
+    //pthread_mutex_unlock(&qset->mutex);
     if (queue == NULL) break;
 
     pthread_mutex_lock(&queue->mutex);
@@ -326,6 +328,8 @@ int taosReadQitemFromQset(taos_qset param, int *type, void **pitem, void **phand
     if (pNode) break;
   }
 
+  pthread_mutex_unlock(&qset->mutex);
+
   return code; 
 }
 
@@ -335,13 +339,15 @@ int taosReadAllQitemsFromQset(taos_qset param, taos_qall p2, void **phandle) {
   STaosQall  *qall = (STaosQall *)p2;
   int         code = 0;
 
+  pthread_mutex_lock(&qset->mutex);
+
   for(int i=0; i<qset->numOfQueues; ++i) {
-    pthread_mutex_lock(&qset->mutex);
+    // pthread_mutex_lock(&qset->mutex);
     if (qset->current == NULL) 
       qset->current = qset->head;   
     queue = qset->current;
     if (queue) qset->current = queue->next;
-    pthread_mutex_unlock(&qset->mutex);
+    // pthread_mutex_unlock(&qset->mutex);
     if (queue == NULL) break;
 
     pthread_mutex_lock(&queue->mutex);
@@ -365,6 +371,7 @@ int taosReadAllQitemsFromQset(taos_qset param, taos_qall p2, void **phandle) {
     if (code != 0) break;  
   }
 
+  pthread_mutex_unlock(&qset->mutex);
   return code;
 }
 
diff --git a/src/util/src/tsched.c b/src/util/src/tsched.c
index 56d16eeb71..8608b64057 100644
--- a/src/util/src/tsched.c
+++ b/src/util/src/tsched.c
@@ -40,66 +40,68 @@ static void *taosProcessSchedQueue(void *param);
 static void taosDumpSchedulerStatus(void *qhandle, void *tmrId);
 
 void *taosInitScheduler(int queueSize, int numOfThreads, const char *label) {
-  pthread_attr_t attr;
-  SSchedQueue *  pSched = (SSchedQueue *)malloc(sizeof(SSchedQueue));
+  SSchedQueue *pSched = (SSchedQueue *)calloc(sizeof(SSchedQueue), 1);
   if (pSched == NULL) {
-    pError("%s: no enough memory for pSched, reason: %s", label, strerror(errno));
-    goto _error;
+    pError("%s: no enough memory for pSched", label);
+    return NULL;
+  }
+
+  pSched->queue = (SSchedMsg *)calloc(sizeof(SSchedMsg), queueSize);
+  if (pSched->queue == NULL) {
+    pError("%s: no enough memory for queue", label);
+    taosCleanUpScheduler(pSched);
+    return NULL;
+  }
+
+  pSched->qthread = calloc(sizeof(pthread_t), numOfThreads);
+  if (pSched->qthread == NULL) {
+    pError("%s: no enough memory for qthread", label);
+    taosCleanUpScheduler(pSched);
+    return NULL;
   }
 
-  memset(pSched, 0, sizeof(SSchedQueue));
   pSched->queueSize = queueSize;
   strncpy(pSched->label, label, sizeof(pSched->label)); // fix buffer overflow
   pSched->label[sizeof(pSched->label)-1] = '\0';
 
-  if (pthread_mutex_init(&pSched->queueMutex, NULL) < 0) {
-    pError("init %s:queueMutex failed, reason:%s", pSched->label, strerror(errno));
-    goto _error;
-  }
-
-  if (tsem_init(&pSched->emptySem, 0, (unsigned int)pSched->queueSize) != 0) {
-    pError("init %s:empty semaphore failed, reason:%s", pSched->label, strerror(errno));
-    goto _error;
-  }
-
-  if (tsem_init(&pSched->fullSem, 0, 0) != 0) {
-    pError("init %s:full semaphore failed, reason:%s", pSched->label, strerror(errno));
-    goto _error;
-  }
-
-  if ((pSched->queue = (SSchedMsg *)malloc((size_t)pSched->queueSize * sizeof(SSchedMsg))) == NULL) {
-    pError("%s: no enough memory for queue, reason:%s", pSched->label, strerror(errno));
-    goto _error;
-  }
-
-  memset(pSched->queue, 0, (size_t)pSched->queueSize * sizeof(SSchedMsg));
   pSched->fullSlot = 0;
   pSched->emptySlot = 0;
 
-  pSched->qthread = malloc(sizeof(pthread_t) * (size_t)numOfThreads);
-  if (pSched->qthread == NULL) {
-    pError("%s: no enough memory for qthread, reason: %s", pSched->label, strerror(errno));
-    goto _error;
+  if (pthread_mutex_init(&pSched->queueMutex, NULL) < 0) {
+    pError("init %s:queueMutex failed(%s)", label, strerror(errno));
+    taosCleanUpScheduler(pSched);
+    return NULL;
   }
 
-  pthread_attr_init(&attr);
-  pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_JOINABLE);
+  if (tsem_init(&pSched->emptySem, 0, (unsigned int)pSched->queueSize) != 0) {
+    pError("init %s:empty semaphore failed(%s)", label, strerror(errno));
+    taosCleanUpScheduler(pSched);
+    return NULL;
+  }
+
+  if (tsem_init(&pSched->fullSem, 0, 0) != 0) {
+    pError("init %s:full semaphore failed(%s)", label, strerror(errno));
+    taosCleanUpScheduler(pSched);
+    return NULL;
+  }
 
   for (int i = 0; i < numOfThreads; ++i) {
-    if (pthread_create(pSched->qthread + i, &attr, taosProcessSchedQueue, (void *)pSched) != 0) {
-      pError("%s: failed to create rpc thread, reason:%s", pSched->label, strerror(errno));
-      goto _error;
+    pthread_attr_t attr;
+    pthread_attr_init(&attr);
+    pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_JOINABLE);
+    int code = pthread_create(pSched->qthread + i, &attr, taosProcessSchedQueue, (void *)pSched);
+    pthread_attr_destroy(&attr);
+    if (code != 0) {
+      pError("%s: failed to create rpc thread(%s)", label, strerror(errno));
+      taosCleanUpScheduler(pSched);
+      return NULL;
     }
     ++pSched->numOfThreads;
   }
 
-  pTrace("%s scheduler is initialized, numOfThreads:%d", pSched->label, pSched->numOfThreads);
+  pTrace("%s scheduler is initialized, numOfThreads:%d", label, pSched->numOfThreads);
 
   return (void *)pSched;
-
-_error:
-  taosCleanUpScheduler(pSched);
-  return NULL;
 }
 
 void *taosInitSchedulerWithInfo(int queueSize, int numOfThreads, const char *label, void *tmrCtrl) {
@@ -124,21 +126,21 @@ void *taosProcessSchedQueue(void *param) {
         pTrace("wait %s fullSem was interrupted", pSched->label);
         continue;
       }
-      pError("wait %s fullSem failed, errno:%d, reason:%s", pSched->label, errno, strerror(errno));
+      pError("wait %s fullSem failed(%s)", pSched->label, strerror(errno));
     }
 
     if (pthread_mutex_lock(&pSched->queueMutex) != 0)
-      pError("lock %s queueMutex failed, reason:%s", pSched->label, strerror(errno));
+      pError("lock %s queueMutex failed(%s)", pSched->label, strerror(errno));
 
     msg = pSched->queue[pSched->fullSlot];
     memset(pSched->queue + pSched->fullSlot, 0, sizeof(SSchedMsg));
     pSched->fullSlot = (pSched->fullSlot + 1) % pSched->queueSize;
 
     if (pthread_mutex_unlock(&pSched->queueMutex) != 0)
-      pError("unlock %s queueMutex failed, reason:%s\n", pSched->label, strerror(errno));
+      pError("unlock %s queueMutex failed(%s)", pSched->label, strerror(errno));
 
     if (tsem_post(&pSched->emptySem) != 0)
-      pError("post %s emptySem failed, reason:%s\n", pSched->label, strerror(errno));
+      pError("post %s emptySem failed(%s)", pSched->label, strerror(errno));
 
     if (msg.fp)
       (*(msg.fp))(&msg);
@@ -158,22 +160,23 @@ int taosScheduleTask(void *qhandle, SSchedMsg *pMsg) {
 
   while (tsem_wait(&pSched->emptySem) != 0) {
     if (errno != EINTR) {
-      pError("wait %s emptySem failed, reason:%s", pSched->label, strerror(errno));
+      pError("wait %s emptySem failed(%s)", pSched->label, strerror(errno));
       break;
     }
     pTrace("wait %s emptySem was interrupted", pSched->label);
   }
 
   if (pthread_mutex_lock(&pSched->queueMutex) != 0)
-    pError("lock %s queueMutex failed, reason:%s", pSched->label, strerror(errno));
+    pError("lock %s queueMutex failed(%s)", pSched->label, strerror(errno));
 
   pSched->queue[pSched->emptySlot] = *pMsg;
   pSched->emptySlot = (pSched->emptySlot + 1) % pSched->queueSize;
 
   if (pthread_mutex_unlock(&pSched->queueMutex) != 0)
-    pError("unlock %s queueMutex failed, reason:%s", pSched->label, strerror(errno));
+    pError("unlock %s queueMutex failed(%s)", pSched->label, strerror(errno));
 
-  if (tsem_post(&pSched->fullSem) != 0) pError("post %s fullSem failed, reason:%s", pSched->label, strerror(errno));
+  if (tsem_post(&pSched->fullSem) != 0) 
+    pError("post %s fullSem failed(%s)", pSched->label, strerror(errno));
 
   return 0;
 }
@@ -183,10 +186,12 @@ void taosCleanUpScheduler(void *param) {
   if (pSched == NULL) return;
 
   for (int i = 0; i < pSched->numOfThreads; ++i) {
-    pthread_cancel(pSched->qthread[i]);
+    if (pSched->qthread[i])
+      pthread_cancel(pSched->qthread[i]);
   }
   for (int i = 0; i < pSched->numOfThreads; ++i) {
-    pthread_join(pSched->qthread[i], NULL);
+    if (pSched->qthread[i]) 
+      pthread_join(pSched->qthread[i], NULL);
   }
 
   tsem_destroy(&pSched->emptySem);
@@ -197,8 +202,8 @@ void taosCleanUpScheduler(void *param) {
     taosTmrStopA(&pSched->pTimer);
   }
 
-  free(pSched->queue);
-  free(pSched->qthread);
+  if (pSched->queue) free(pSched->queue);
+  if (pSched->qthread) free(pSched->qthread);
   free(pSched); // fix memory leak
 }
 
diff --git a/src/vnode/main/src/vnodeMain.c b/src/vnode/main/src/vnodeMain.c
index ea7a003d3d..4d77e007ad 100644
--- a/src/vnode/main/src/vnodeMain.c
+++ b/src/vnode/main/src/vnodeMain.c
@@ -224,10 +224,11 @@ void vnodeRelease(void *pVnodeRaw) {
     // remove the whole directory
   }
 
-  dTrace("pVnode:%p vgId:%d, vnode is released", pVnode, pVnode->vgId);
   free(pVnode);
 
   int32_t count = atomic_sub_fetch_32(&tsOpennedVnodes, 1);
+  dTrace("pVnode:%p vgId:%d, vnode is released, vnodes:%d", pVnode, vgId, count);
+
   if (count <= 0) {
     taosCleanUpIntHash(tsDnodeVnodesHash);
     vnodeModuleInit = PTHREAD_ONCE_INIT;
diff --git a/src/vnode/tsdb/inc/tsdbMain.h b/src/vnode/tsdb/inc/tsdbMain.h
index 06f62ea6f7..077bdf45c3 100644
--- a/src/vnode/tsdb/inc/tsdbMain.h
+++ b/src/vnode/tsdb/inc/tsdbMain.h
@@ -222,8 +222,9 @@ int         tsdbOpenFile(SFile *pFile, int oflag);
 int         tsdbCloseFile(SFile *pFile); SFileGroup *tsdbOpenFilesForCommit(STsdbFileH *pFileH, int fid);
 int         tsdbRemoveFileGroup(STsdbFileH *pFile, int fid);
 
-#define TSDB_FGROUP_ITER_FORWARD 0
-#define TSDB_FGROUP_ITER_BACKWARD 1
+#define TSDB_FGROUP_ITER_FORWARD  TSDB_ORDER_ASC
+#define TSDB_FGROUP_ITER_BACKWARD TSDB_ORDER_DESC
+
 typedef struct {
   int         numOfFGroups;
   SFileGroup *base;
diff --git a/src/vnode/tsdb/src/tsdbFile.c b/src/vnode/tsdb/src/tsdbFile.c
index 8bdfe63002..d025144ba9 100644
--- a/src/vnode/tsdb/src/tsdbFile.c
+++ b/src/vnode/tsdb/src/tsdbFile.c
@@ -154,7 +154,7 @@ void tsdbSeekFileGroupIter(SFileGroupIter *pIter, int fid) {
   }
   
   int flags = (pIter->direction == TSDB_FGROUP_ITER_FORWARD) ? TD_GE : TD_LE;
-  void *ptr = taosbsearch(&fid, pIter->base, sizeof(SFileGroup), pIter->numOfFGroups, compFGroupKey, flags);
+  void *ptr = taosbsearch(&fid, pIter->base, pIter->numOfFGroups, sizeof(SFileGroup), compFGroupKey, flags);
   if (ptr == NULL) {
     pIter->pFileGroup = NULL;
   } else {
@@ -173,7 +173,7 @@ SFileGroup *tsdbGetFileGroupNext(SFileGroupIter *pIter) {
       pIter->pFileGroup += 1;
     }
   } else {
-    if (pIter->pFileGroup - 1 == pIter->base) {
+    if (pIter->pFileGroup == pIter->base) {
       pIter->pFileGroup = NULL;
     } else {
       pIter->pFileGroup -= 1;
diff --git a/src/vnode/tsdb/src/tsdbRead.c b/src/vnode/tsdb/src/tsdbRead.c
index e5f0aed05e..2fce73e547 100644
--- a/src/vnode/tsdb/src/tsdbRead.c
+++ b/src/vnode/tsdb/src/tsdbRead.c
@@ -27,7 +27,7 @@
 #define EXTRA_BYTES 2
 #define PRIMARY_TSCOL_REQUIRED(c) (((SColumnInfoData*)taosArrayGet(c, 0))->info.colId == PRIMARYKEY_TIMESTAMP_COL_INDEX)
 #define QUERY_IS_ASC_QUERY(o) (o == TSDB_ORDER_ASC)
-#define QH_GET_NUM_OF_COLS(handle) (taosArrayGetSize((handle)->pColumns))
+#define QH_GET_NUM_OF_COLS(handle) ((size_t)(taosArrayGetSize((handle)->pColumns)))
 
 enum {
   QUERY_RANGE_LESS_EQUAL = 0,
@@ -87,14 +87,8 @@ typedef struct STableBlockInfo {
   int32_t          groupIdx; /* number of group is less than the total number of tables */
 } STableBlockInfo;
 
-enum {
-  SINGLE_TABLE_MODEL = 1,
-  MULTI_TABLE_MODEL = 2,
-};
-
 typedef struct STsdbQueryHandle {
   STsdbRepo*    pTsdb;
-  int8_t        model;  // access model, single table model or multi-table model
   SQueryFilePos cur;    // current position
   SQueryFilePos start;  // the start position, used for secondary/third iteration
 
@@ -128,21 +122,6 @@ typedef struct STsdbQueryHandle {
   SCompIdx*      compIndex;
 } STsdbQueryHandle;
 
-int32_t doAllocateBuf(STsdbQueryHandle* pQueryHandle, int32_t rowsPerFileBlock) {
-  // record the maximum column width among columns of this meter/metric
-  SColumnInfoData* pColumn = taosArrayGet(pQueryHandle->pColumns, 0);
-
-  int32_t maxColWidth = pColumn->info.bytes;
-  for (int32_t i = 1; i < QH_GET_NUM_OF_COLS(pQueryHandle); ++i) {
-    int32_t bytes = pColumn[i].info.bytes;
-    if (bytes > maxColWidth) {
-      maxColWidth = bytes;
-    }
-  }
-
-  return TSDB_CODE_SUCCESS;
-}
-
 static void tsdbInitDataBlockLoadInfo(SDataBlockLoadInfo* pBlockLoadInfo) {
   pBlockLoadInfo->slot = -1;
   pBlockLoadInfo->sid = -1;
@@ -161,9 +140,9 @@ tsdb_query_handle_t* tsdbQueryByTableId(tsdb_repo_t* tsdb, STsdbQueryCond* pCond
   // todo 2. add the reference count for each table that is involved in query
 
   STsdbQueryHandle* pQueryHandle = calloc(1, sizeof(STsdbQueryHandle));
-  pQueryHandle->order = pCond->order;
+  pQueryHandle->order  = pCond->order;
   pQueryHandle->window = pCond->twindow;
-  pQueryHandle->pTsdb = tsdb;
+  pQueryHandle->pTsdb  = tsdb;
   pQueryHandle->compIndex = calloc(10000, sizeof(SCompIdx)),
 
   pQueryHandle->loadDataAfterSeek = false;
@@ -174,25 +153,33 @@ tsdb_query_handle_t* tsdbQueryByTableId(tsdb_repo_t* tsdb, STsdbQueryCond* pCond
 
   pQueryHandle->pTableCheckInfo = taosArrayInit(size, sizeof(STableCheckInfo));
   for (int32_t i = 0; i < size; ++i) {
-    STableId id = *(STableId*)taosArrayGet(idList, i);
-
+    STableId id = *(STableId*) taosArrayGet(idList, i);
+    
+    STable* pTable = tsdbGetTableByUid(tsdbGetMeta(tsdb), id.uid);
+    if (pTable == NULL) {
+      dError("%p failed to get table, error uid:%" PRIu64, pQueryHandle, id.uid);
+      continue;
+    }
+    
     STableCheckInfo info = {
-        .lastKey = pQueryHandle->window.skey,
-        .tableId = id,
-        .pTableObj = tsdbGetTableByUid(tsdbGetMeta(tsdb), id.uid),  // todo this may be failed
-        .pCompInfo = NULL,
+      .lastKey = pQueryHandle->window.skey,
+      .tableId = id,
+      .pTableObj = pTable,
     };
 
-    assert(info.pTableObj != NULL);
     taosArrayPush(pQueryHandle->pTableCheckInfo, &info);
   }
 
-  pQueryHandle->model = (size > 1) ? MULTI_TABLE_MODEL : SINGLE_TABLE_MODEL;
-  pQueryHandle->checkFiles = 1;
-
+  dTrace("%p total numOfTable:%d in query", pQueryHandle, taosArrayGetSize(pQueryHandle->pTableCheckInfo));
+  
+  /*
+   * For ascending timestamp order query, query starts from data files. In contrast, buffer will be checked in the first place
+   * in case of descending timestamp order query.
+   */
+  pQueryHandle->checkFiles  = QUERY_IS_ASC_QUERY(pQueryHandle->order);
   pQueryHandle->activeIndex = 0;
 
-  // malloc buffer in order to load data from file
+  // allocate buffer in order to load data blocks from file
   int32_t numOfCols = taosArrayGetSize(pColumnInfo);
   size_t  bufferCapacity = 4096;
 
@@ -206,10 +193,6 @@ tsdb_query_handle_t* tsdbQueryByTableId(tsdb_repo_t* tsdb, STsdbQueryCond* pCond
     taosArrayPush(pQueryHandle->pColumns, &pDest);
   }
 
-  if (doAllocateBuf(pQueryHandle, bufferCapacity) != TSDB_CODE_SUCCESS) {
-    return NULL;
-  }
-
   tsdbInitDataBlockLoadInfo(&pQueryHandle->dataBlockLoadInfo);
   tsdbInitCompBlockLoadInfo(&pQueryHandle->compBlockLoadInfo);
 
@@ -239,7 +222,12 @@ static bool hasMoreDataInCache(STsdbQueryHandle* pHandle) {
 
 // todo dynamic get the daysperfile
 static int32_t getFileIdFromKey(TSKEY key) {
-  return (int32_t)(key / 10);  // set the starting fileId
+  int64_t fid = (int64_t)(key / 10);  // set the starting fileId
+  if (fid > INT32_MAX) {
+    fid = INT32_MAX;
+  }
+  
+  return fid;
 }
 
 static int32_t binarySearchForBlockImpl(SCompBlock* pBlock, int32_t numOfBlocks, TSKEY skey, int32_t order);
@@ -247,8 +235,12 @@ static int32_t binarySearchForBlockImpl(SCompBlock* pBlock, int32_t numOfBlocks,
 static int32_t getFileCompInfo(STsdbQueryHandle* pQueryHandle, int32_t* numOfBlocks, int32_t type) {
   // todo check open file failed
   SFileGroup* fileGroup = pQueryHandle->pFileGroup;
+  
+  assert(fileGroup->files[TSDB_FILE_TYPE_HEAD].fname > 0);
   if (fileGroup->files[TSDB_FILE_TYPE_HEAD].fd == FD_INITIALIZER) {
     fileGroup->files[TSDB_FILE_TYPE_HEAD].fd = open(fileGroup->files[TSDB_FILE_TYPE_HEAD].fname, O_RDONLY);
+  } else {
+    assert(FD_VALID(fileGroup->files[TSDB_FILE_TYPE_HEAD].fd));
   }
 
   // load all the comp offset value for all tables in this file
@@ -262,7 +254,7 @@ static int32_t getFileCompInfo(STsdbQueryHandle* pQueryHandle, int32_t* numOfBlo
 
     SCompIdx* compIndex = &pQueryHandle->compIndex[pCheckInfo->tableId.tid];
     if (compIndex->len == 0 || compIndex->numOfSuperBlocks == 0) {  // no data block in this file, try next file
-
+      assert(0);
     } else {
       if (pCheckInfo->compSize < compIndex->len) {
         assert(compIndex->len > 0);
@@ -271,46 +263,35 @@ static int32_t getFileCompInfo(STsdbQueryHandle* pQueryHandle, int32_t* numOfBlo
         assert(t != NULL);
         
         pCheckInfo->pCompInfo = (SCompInfo*) t;
+        pCheckInfo->compSize = compIndex->len;
       }
       
       tsdbLoadCompBlocks(fileGroup, compIndex, pCheckInfo->pCompInfo);
-
-      int32_t index = 0;
+  
+      SCompInfo* pCompInfo = pCheckInfo->pCompInfo;
+      
+      TSKEY s = MIN(pCheckInfo->lastKey, pQueryHandle->window.ekey);
+      TSKEY e = MAX(pCheckInfo->lastKey, pQueryHandle->window.ekey);
+      
       // discard the unqualified data block based on the query time window
-      int32_t start = binarySearchForBlockImpl(pCheckInfo->pCompInfo->blocks, compIndex->numOfSuperBlocks,
-                                               pQueryHandle->order, pCheckInfo->lastKey);
-
-      if (type == QUERY_RANGE_GREATER_EQUAL) {
-        if (pCheckInfo->lastKey <= pCheckInfo->pCompInfo->blocks[start].keyLast) {
-          //          break;
-        } else {
-          index = -1;
-        }
-      } else {
-        if (pCheckInfo->lastKey >= pCheckInfo->pCompInfo->blocks[start].keyFirst) {
-          //          break;
-        } else {
-          index = -1;
-        }
-      }
-
-      // not found in data blocks in current file
-      if (index == -1) {
+      int32_t start = binarySearchForBlockImpl(pCompInfo->blocks, compIndex->numOfSuperBlocks, s, TSDB_ORDER_ASC);
+      int32_t end = start;
+      
+      if (s > pCompInfo->blocks[start].keyLast) {
         continue;
       }
 
-      // todo speedup the procedure of locating end block
-      int32_t e = start;
-      while (e < compIndex->numOfSuperBlocks &&
-             (pCheckInfo->pCompInfo->blocks[e].keyFirst <= pQueryHandle->window.ekey)) {
-        e += 1;
+      // todo speedup the procedure of located end block
+      while (end < compIndex->numOfSuperBlocks && (pCompInfo->blocks[end].keyFirst <= e)) {
+        end += 1;
       }
 
+      pCheckInfo->numOfBlocks = (end - start);
+      
       if (start > 0) {
-        memmove(pCheckInfo->pCompInfo->blocks, &pCheckInfo->pCompInfo->blocks[start], (e - start) * sizeof(SCompBlock));
+        memmove(pCompInfo->blocks, &pCompInfo->blocks[start], pCheckInfo->numOfBlocks * sizeof(SCompBlock));
       }
 
-      pCheckInfo->numOfBlocks = (e - start);
       (*numOfBlocks) += pCheckInfo->numOfBlocks;
     }
   }
@@ -413,7 +394,6 @@ static bool loadFileDataBlock(STsdbQueryHandle* pQueryHandle, SCompBlock* pBlock
       }
 
       SDataCols* pDataCols = pCheckInfo->pDataCols;
-
       if (pCheckInfo->lastKey > pBlock->keyFirst) {
         cur->pos =
             binarySearchForKey(pDataCols->cols[0].pData, pBlock->numOfPoints, pCheckInfo->lastKey, pQueryHandle->order);
@@ -425,8 +405,24 @@ static bool loadFileDataBlock(STsdbQueryHandle* pQueryHandle, SCompBlock* pBlock
     } else {  // the whole block is loaded in to buffer
       pQueryHandle->realNumOfRows = pBlock->numOfPoints;
     }
-  } else {  // todo desc query
+  } else {
+    // query ended in current block
     if (pQueryHandle->window.ekey > pBlock->keyFirst) {
+      if (!doLoadFileDataBlock(pQueryHandle, pBlock, pCheckInfo)) {
+        return false;
+      }
+      
+      SDataCols* pDataCols = pCheckInfo->pDataCols;
+      if (pCheckInfo->lastKey < pBlock->keyLast) {
+        cur->pos =
+            binarySearchForKey(pDataCols->cols[0].pData, pBlock->numOfPoints, pCheckInfo->lastKey, pQueryHandle->order);
+      } else {
+        cur->pos = pBlock->numOfPoints - 1;
+      }
+      
+      filterDataInDataBlock(pQueryHandle, pCheckInfo, pBlock, sa);
+    } else {
+      pQueryHandle->realNumOfRows = pBlock->numOfPoints;
     }
   }
 
@@ -619,7 +615,9 @@ static void filterDataInDataBlock(STsdbQueryHandle* pQueryHandle, STableCheckInf
 }
 
 static SArray* getColumnIdList(STsdbQueryHandle* pQueryHandle) {
-  int32_t numOfCols = QH_GET_NUM_OF_COLS(pQueryHandle);
+  size_t numOfCols = QH_GET_NUM_OF_COLS(pQueryHandle);
+  assert(numOfCols <= TSDB_MAX_COLUMNS);
+  
   SArray* pIdList = taosArrayInit(numOfCols, sizeof(int16_t));
   for (int32_t i = 0; i < numOfCols; ++i) {
     SColumnInfoData* pCol = taosArrayGet(pQueryHandle->pColumns, i);
@@ -923,8 +921,8 @@ static bool getDataBlocksInFiles(STsdbQueryHandle* pQueryHandle) {
     pQueryHandle->locateStart = true;
 
     int32_t fid = getFileIdFromKey(pQueryHandle->window.skey);
-
-    tsdbInitFileGroupIter(pFileHandle, &pQueryHandle->fileIter, TSDB_FGROUP_ITER_FORWARD);
+    
+    tsdbInitFileGroupIter(pFileHandle, &pQueryHandle->fileIter, pQueryHandle->order);
     tsdbSeekFileGroupIter(&pQueryHandle->fileIter, fid);
 
     int32_t numOfBlocks = -1;
@@ -934,13 +932,14 @@ static bool getDataBlocksInFiles(STsdbQueryHandle* pQueryHandle) {
     int32_t numOfTables = taosArrayGetSize(pQueryHandle->pTableCheckInfo);
 
     while ((pQueryHandle->pFileGroup = tsdbGetFileGroupNext(&pQueryHandle->fileIter)) != NULL) {
-      if (getFileCompInfo(pQueryHandle, &numOfBlocks, 1) != TSDB_CODE_SUCCESS) {
+      int32_t type = QUERY_IS_ASC_QUERY(pQueryHandle->order)? QUERY_RANGE_GREATER_EQUAL:QUERY_RANGE_LESS_EQUAL;
+      if (getFileCompInfo(pQueryHandle, &numOfBlocks, type) != TSDB_CODE_SUCCESS) {
         break;
       }
 
       assert(numOfBlocks >= 0);
       dTrace("%p %d blocks found in file for %d table(s), fid:%d", pQueryHandle, numOfBlocks,
-             pQueryHandle->pFileGroup->fileId, numOfTables);
+             numOfTables, pQueryHandle->pFileGroup->fileId);
       
       // todo return error code to query engine
       if (createDataBlocksInfo(pQueryHandle, numOfBlocks, &pQueryHandle->numOfBlocks) != TSDB_CODE_SUCCESS) {
@@ -961,7 +960,7 @@ static bool getDataBlocksInFiles(STsdbQueryHandle* pQueryHandle) {
       return false;
     }
 
-    cur->slot = 0;
+    cur->slot = QUERY_IS_ASC_QUERY(pQueryHandle->order)? 0:pQueryHandle->numOfBlocks-1;
     cur->fid = pQueryHandle->pFileGroup->fileId;
 
     STableBlockInfo* pBlockInfo = &pQueryHandle->pDataBlockInfo[cur->slot];
@@ -970,8 +969,10 @@ static bool getDataBlocksInFiles(STsdbQueryHandle* pQueryHandle) {
     
     return loadFileDataBlock(pQueryHandle, pBlock, pCheckInfo);
   } else {
-    if (cur->slot == pQueryHandle->numOfBlocks - 1) { // all blocks
+    if ((cur->slot == pQueryHandle->numOfBlocks - 1 && QUERY_IS_ASC_QUERY(pQueryHandle->order)) ||
+        (cur->slot == 0 && !QUERY_IS_ASC_QUERY(pQueryHandle->order))) { // all blocks
       int32_t numOfBlocks = -1;
+      
       int32_t numOfTables = taosArrayGetSize(pQueryHandle->pTableCheckInfo);
       pQueryHandle->numOfBlocks = 0;
       
@@ -1001,67 +1002,84 @@ static bool getDataBlocksInFiles(STsdbQueryHandle* pQueryHandle) {
         cur->fid = -1;
         return false;
       }
-
-      cur->slot = 0;
+  
+      cur->slot = QUERY_IS_ASC_QUERY(pQueryHandle->order)? 0:pQueryHandle->numOfBlocks-1;
       cur->fid = pQueryHandle->pFileGroup->fileId;
       
       STableBlockInfo* pBlockInfo = &pQueryHandle->pDataBlockInfo[cur->slot];
-
       STableCheckInfo* pCheckInfo = pBlockInfo->pTableCheckInfo;
       SCompBlock*      pBlock = pBlockInfo->pBlock.compBlock;
       
       return loadFileDataBlock(pQueryHandle, pBlock, pCheckInfo);
     } else {  // next block of the same file
-      cur->slot += 1;
-      cur->pos = 0;
-
+      int32_t step = QUERY_IS_ASC_QUERY(pQueryHandle->order)? 1:-1;
+      cur->slot += step;
+      
       STableBlockInfo* pBlockInfo = &pQueryHandle->pDataBlockInfo[cur->slot];
+      if (QUERY_IS_ASC_QUERY(pQueryHandle->order)) {
+        cur->pos = 0;
+      } else {
+        cur->pos = pBlockInfo->pBlock.compBlock->numOfPoints - 1;
+      }
+
       return loadFileDataBlock(pQueryHandle, pBlockInfo->pBlock.compBlock, pBlockInfo->pTableCheckInfo);
     }
   }
 }
 
-// handle data in cache situation
-bool tsdbNextDataBlock(tsdb_query_handle_t* pQueryHandle) {
-  STsdbQueryHandle* pHandle = (STsdbQueryHandle*)pQueryHandle;
-  
-  size_t numOfTables = taosArrayGetSize(pHandle->pTableCheckInfo);
+
+static bool doHasDataInBuffer(STsdbQueryHandle* pQueryHandle) {
+  size_t numOfTables = taosArrayGetSize(pQueryHandle->pTableCheckInfo);
+  // todo add assert, the value of numOfTables should be less than the maximum value for each vnode capacity
   assert(numOfTables > 0);
   
-  if (pHandle->checkFiles) {
-    if (getDataBlocksInFiles(pHandle)) {
+  while (pQueryHandle->activeIndex < numOfTables) {
+    if (hasMoreDataInCache(pQueryHandle)) {
       return true;
     }
     
-    pHandle->activeIndex = 0;
-    pHandle->checkFiles = 0;
-    
-    while (pHandle->activeIndex < numOfTables) {
-      if (hasMoreDataInCache(pHandle)) {
-        return true;
-      }
-      
-      pHandle->activeIndex += 1;
-    }
-    
-    return false;
-  } else {
-    while (pHandle->activeIndex < numOfTables) {
-      if (hasMoreDataInCache(pHandle)) {
-        return true;
-      }
-      
-      pHandle->activeIndex += 1;
-    }
-    
-    return false;
+    pQueryHandle->activeIndex += 1;
   }
+  
+  return false;
+}
+
+// handle data in cache situation
+bool tsdbNextDataBlock(tsdb_query_handle_t* pqHandle) {
+  STsdbQueryHandle* pQueryHandle = (STsdbQueryHandle*) pqHandle;
+  
+  size_t numOfTables = taosArrayGetSize(pQueryHandle->pTableCheckInfo);
+  assert(numOfTables > 0);
+  
+  if (QUERY_IS_ASC_QUERY(pQueryHandle->order)) {
+    if (pQueryHandle->checkFiles) {
+      if (getDataBlocksInFiles(pQueryHandle)) {
+        return true;
+      }
+
+      pQueryHandle->activeIndex = 0;
+      pQueryHandle->checkFiles  = false;
+    }
+    
+    return doHasDataInBuffer(pQueryHandle);
+  } else {  // starts from the buffer in case of descending timestamp order check data blocks
+    if (!pQueryHandle->checkFiles) {
+      if (doHasDataInBuffer(pQueryHandle)) {
+        return true;
+      }
+      
+      pQueryHandle->checkFiles = true;
+    }
+
+    return getDataBlocksInFiles(pQueryHandle);
+  }
+  
 }
 
 static int tsdbReadRowsFromCache(SSkipListIterator* pIter, TSKEY maxKey, int maxRowsToRead, TSKEY* skey, TSKEY* ekey,
-                                 STsdbQueryHandle* pHandle) {
+                                 STsdbQueryHandle* pQueryHandle) {
   int     numOfRows = 0;
-  int32_t numOfCols = taosArrayGetSize(pHandle->pColumns);
+  int32_t numOfCols = taosArrayGetSize(pQueryHandle->pColumns);
   *skey = INT64_MIN;
 
   while (tSkipListIterNext(pIter)) {
@@ -1079,7 +1097,7 @@ static int tsdbReadRowsFromCache(SSkipListIterator* pIter, TSKEY maxKey, int max
 
     int32_t offset = 0;
     for (int32_t i = 0; i < numOfCols; ++i) {
-      SColumnInfoData* pColInfo = taosArrayGet(pHandle->pColumns, i);
+      SColumnInfoData* pColInfo = taosArrayGet(pQueryHandle->pColumns, i);
       memcpy(pColInfo->pData + numOfRows * pColInfo->info.bytes, dataRowTuple(row) + offset, pColInfo->info.bytes);
       offset += pColInfo->info.bytes;
     }
diff --git a/tests/pytest/insert/__init__.py b/tests/pytest/insert/__init__.py
new file mode 100644
index 0000000000..e69de29bb2
diff --git a/tests/pytest/insert/basic.py b/tests/pytest/insert/basic.py
new file mode 100644
index 0000000000..c6dbd76de4
--- /dev/null
+++ b/tests/pytest/insert/basic.py
@@ -0,0 +1,53 @@
+###################################################################
+#           Copyright (c) 2016 by TAOS Technologies, Inc.
+#                     All rights reserved.
+#
+#  This file is proprietary and confidential to TAOS Technologies.
+#  No part of this file may be reproduced, stored, transmitted,
+#  disclosed or used in any form or by any means other than as
+#  expressly provided by the written permission from Jianhui Tao
+#
+###################################################################
+
+# -*- coding: utf-8 -*-
+
+import sys
+import taos
+from util.log import *
+from util.cases import *
+from util.sql import *
+
+class TDTestCase:
+    def init(self, conn):
+        tdLog.debug("start to execute %s" % __file__)
+        tdSql.init(conn.cursor())
+
+    def run(self):
+        tdSql.prepare()
+        tdSql.execute('show databases')
+        tdSql.execute('drop database if exists db')
+        tdSql.execute('create database db')
+        tdSql.execute('use db')
+        tdSql.execute('create table tb (ts timestamp, speed int)')
+
+        insertRows = 10
+        tdLog.info("insert %d rows" % (insertRows))
+        for i in range(0, insertRows):
+            tdSql.execute('insert into tb values (now + %dm, %d)' % (i, i))
+
+#        tdLog.info("insert earlier data")
+#        tdSql.execute('insert into tb values (now - 5m , 10)')
+#        tdSql.execute('insert into tb values (now - 6m , 10)')
+#        tdSql.execute('insert into tb values (now - 7m , 10)')
+#        tdSql.execute('insert into tb values (now - 8m , 10)')
+
+#        tdSql.query("select * from tb")
+#        tdSql.checkRows(insertRows)
+
+    def stop(self):
+        tdSql.close()
+        tdLog.success("%s successfully executed" % __file__)
+
+
+tdCases.addWindows(__file__, TDTestCase())
+tdCases.addLinux(__file__, TDTestCase())
diff --git a/tests/pytest/simpletest.sh b/tests/pytest/simpletest.sh
new file mode 100755
index 0000000000..aab36884f3
--- /dev/null
+++ b/tests/pytest/simpletest.sh
@@ -0,0 +1 @@
+sudo python2 ./test.py -f insert/basic.py
diff --git a/tests/pytest/test.py b/tests/pytest/test.py
new file mode 100644
index 0000000000..b88e444665
--- /dev/null
+++ b/tests/pytest/test.py
@@ -0,0 +1,87 @@
+#!/usr/bin/python
+###################################################################
+#           Copyright (c) 2016 by TAOS Technologies, Inc.
+#                     All rights reserved.
+#
+#  This file is proprietary and confidential to TAOS Technologies.
+#  No part of this file may be reproduced, stored, transmitted,
+#  disclosed or used in any form or by any means other than as
+#  expressly provided by the written permission from Jianhui Tao
+#
+###################################################################
+# install pip
+# pip install src/connector/python/linux/python2/
+
+# -*- coding: utf-8 -*-
+import sys
+import getopt
+from util.log import *
+from util.dnodes import *
+from util.cases import *
+
+import taos
+
+# add testcase here:
+from insert.basic import *
+
+if __name__ == "__main__":
+    fileName = "all"
+    deployPath = ""
+    masterIp = ""
+    testCluster = False
+    opts, args = getopt.getopt(sys.argv[1:], 'f:p:m:sch', [
+                               'file=', 'path=', 'master', 'stop', 'cluster', 'help'])
+    for key, value in opts:
+        if key in ['-h', '--help']:
+            tdLog.printNoPrefix(
+                'A collection of test cases written using Python')
+            tdLog.printNoPrefix('-f Name of test case file written by Python')
+            tdLog.printNoPrefix('-p Deploy Path for Simulator')
+            tdLog.printNoPrefix('-m Master Ip for Simulator')
+            tdLog.printNoPrefix('-c Test Cluster Flag')
+            tdLog.printNoPrefix('-s stop All dnodes')
+            sys.exit(0)
+        if key in ['-f', '--file']:
+            fileName = value
+        if key in ['-p', '--path']:
+            deployPath = value
+        if key in ['-m', '--master']:
+            masterIp = value
+        if key in ['-c', '--cluster']:
+            testCluster = True
+        if key in ['-s', '--stop']:
+            cmd = "ps -ef|grep -w taosd | grep 'taosd' | grep -v grep | awk '{print $2}' && pkill -9 taosd"
+            os.system(cmd)
+            tdLog.exit('stop All dnodes')
+
+    if masterIp == "":
+        tdDnodes.init(deployPath)
+        if testCluster:
+            tdLog.notice("Procedures for testing cluster")
+            if fileName == "all":
+                tdCases.runAllCluster()
+            else:
+                tdCases.runOneCluster(fileName)
+        else:
+            tdLog.notice("Procedures for testing self-deployment")
+            tdDnodes.stopAll()
+            tdDnodes.deploy(1)
+            tdDnodes.start(1)
+            conn = taos.connect(
+                host='192.168.0.1',
+                config=tdDnodes.getSimCfgPath())
+            if fileName == "all":
+                tdCases.runAllLinux(conn)
+            else:
+                tdLog.info("CBD LN78: %s" % (fileName))
+                tdCases.runOneLinux(conn, fileName)
+            conn.close()
+    else:
+        tdLog.notice("Procedures for tdengine deployed in %s" % (masterIp))
+        conn = taos.connect(host=masterIp, config=tdDnodes.getSimCfgPath())
+        if fileName == "all":
+            tdCases.runAllWindows(conn)
+        else:
+            tdCases.runOneWindows(conn, fileName)
+        conn.close()
+
diff --git a/tests/pytest/util/__init__.py b/tests/pytest/util/__init__.py
new file mode 100644
index 0000000000..e69de29bb2
diff --git a/tests/pytest/util/cases.py b/tests/pytest/util/cases.py
new file mode 100644
index 0000000000..320c9d974f
--- /dev/null
+++ b/tests/pytest/util/cases.py
@@ -0,0 +1,103 @@
+###################################################################
+#           Copyright (c) 2016 by TAOS Technologies, Inc.
+#                     All rights reserved.
+#
+#  This file is proprietary and confidential to TAOS Technologies.
+#  No part of this file may be reproduced, stored, transmitted,
+#  disclosed or used in any form or by any means other than as
+#  expressly provided by the written permission from Jianhui Tao
+#
+###################################################################
+
+# -*- coding: utf-8 -*-
+
+import sys
+import os
+import time
+import datetime
+from util.log import *
+
+
+class TDCase:
+    def __init__(self, name, case):
+        self.name = name
+        self.case = case
+
+
+class TDCases:
+    def __init__(self):
+        self.linuxCases = []
+        self.windowsCases = []
+        self.clusterCases = []
+
+    def addWindows(self, name, case):
+        self.windowsCases.append(TDCase(name, case))
+
+    def addLinux(self, name, case):
+        self.linuxCases.append(TDCase(name, case))
+
+    def addCluster(self, name, case):
+        self.clusterCases.append(TDCase(name, case))
+
+    def runAllLinux(self, conn):
+        tdLog.notice("run total %d cases" % (len(self.linuxCases)))
+        for case in self.linuxCases:
+            case.case.init(conn)
+            case.case.run()
+            case.case.stop()
+        tdLog.notice("total %d cases executed" % (len(self.linuxCases)))
+
+    def runOneLinux(self, conn, fileName):
+        tdLog.notice("run cases like %s" % (fileName))
+        runNum = 0
+        for case in self.linuxCases:
+            if case.name.find(fileName) != -1:
+                case.case.init(conn)
+                case.case.run()
+                case.case.stop()
+                time.sleep(5)
+                runNum += 1
+        tdLog.notice("total %d cases executed" % (runNum))
+
+    def runAllWindows(self, conn):
+        tdLog.notice("run total %d cases" % (len(self.windowsCases)))
+        for case in self.windowsCases:
+            case.case.init(conn)
+            case.case.run()
+            case.case.stop()
+        tdLog.notice("total %d cases executed" % (len(self.windowsCases)))
+
+    def runOneWindows(self, conn, fileName):
+        tdLog.notice("run cases like %s" % (fileName))
+        runNum = 0
+        for case in self.windowsCases:
+            if case.name.find(fileName) != -1:
+                case.case.init(conn)
+                case.case.run()
+                case.case.stop()
+                time.sleep(2)
+                runNum += 1
+        tdLog.notice("total %d cases executed" % (runNum))
+
+    def runAllCluster(self):
+        tdLog.notice("run total %d cases" % (len(self.clusterCases)))
+        for case in self.clusterCases:
+            case.case.init()
+            case.case.run()
+            case.case.stop()
+        tdLog.notice("total %d cases executed" % (len(self.clusterCases)))
+
+    def runOneCluster(self, fileName):
+        tdLog.notice("run cases like %s" % (fileName))
+        runNum = 0
+        for case in self.clusterCases:
+            if case.name.find(fileName) != -1:
+                case.case.init()
+                case.case.run()
+                case.case.stop()
+                time.sleep(2)
+                runNum += 1
+        tdLog.notice("total %d cases executed" % (runNum))
+
+
+tdCases = TDCases()
diff --git a/tests/pytest/util/dnodes.py b/tests/pytest/util/dnodes.py
new file mode 100644
index 0000000000..2be4f94802
--- /dev/null
+++ b/tests/pytest/util/dnodes.py
@@ -0,0 +1,332 @@
+###################################################################
+#           Copyright (c) 2016 by TAOS Technologies, Inc.
+#                     All rights reserved.
+#
+#  This file is proprietary and confidential to TAOS Technologies.
+#  No part of this file may be reproduced, stored, transmitted,
+#  disclosed or used in any form or by any means other than as
+#  expressly provided by the written permission from Jianhui Tao
+#
+###################################################################
+
+# -*- coding: utf-8 -*-
+
+import sys
+import os
+import os.path
+from util.log import *
+
+
+class TDSimClient:
+    def init(self, path):
+        self.path = path
+
+    def getCfgDir(self):
+        return self.cfgDir
+
+    def cfg(self, option, value):
+        cmd = "echo '%s %s' >> %s" % (option, value, self.cfgPath)
+        if os.system(cmd) != 0:
+            tdLog.exit(cmd)
+
+    def deploy(self):
+        self.logDir = "%s/sim/psim/log" % (self.path,)
+        self.cfgDir = "%s/sim/psim/cfg" % (self.path)
+        self.cfgPath = "%s/sim/psim/cfg/taos.cfg" % (self.path)
+
+        cmd = "rm -rf " + self.logDir
+        if os.system(cmd) != 0:
+            tdLog.exit(cmd)
+
+        cmd = "rm -rf " + self.cfgDir
+        if os.system(cmd) != 0:
+            tdLog.exit(cmd)
+
+        cmd = "mkdir -p " + self.logDir
+        if os.system(cmd) != 0:
+            tdLog.exit(cmd)
+
+        cmd = "mkdir -p " + self.cfgDir
+        if os.system(cmd) != 0:
+            tdLog.exit(cmd)
+
+        cmd = "touch " + self.cfgPath
+        if os.system(cmd) != 0:
+            tdLog.exit(cmd)
+
+        self.cfg("masterIp", "192.168.0.1")
+        self.cfg("secondIp", "192.168.0.2")
+        self.cfg("logDir", self.logDir)
+        self.cfg("numOfLogLines", "100000000")
+        self.cfg("numOfThreadsPerCore", "2.0")
+        self.cfg("locale", "en_US.UTF-8")
+        self.cfg("charset", "GBK")
+        self.cfg("asyncLog", "0")
+        self.cfg("anyIp", "0")
+        self.cfg("sdbDebugFlag", "135")
+        self.cfg("rpcDebugFlag", "135")
+        self.cfg("tmrDebugFlag", "131")
+        self.cfg("cDebugFlag", "135")
+        self.cfg("udebugFlag", "135")
+        self.cfg("jnidebugFlag", "135")
+        self.cfg("qdebugFlag", "135")
+        tdLog.debug("psim is deployed and configured by %s" % (self.cfgPath))
+
+
+class TDDnode:
+    def __init__(self, index):
+        self.index = index
+        self.running = 0
+        self.deployed = 0
+
+    def init(self, path):
+        self.path = path
+
+    def deploy(self):
+        self.logDir = "%s/sim/dnode%d/log" % (self.path, self.index)
+        self.dataDir = "%s/sim/dnode%d/data" % (self.path, self.index)
+        self.cfgDir = "%s/sim/dnode%d/cfg" % (self.path, self.index)
+        self.cfgPath = "%s/sim/dnode%d/cfg/taos.cfg" % (self.path, self.index)
+
+        cmd = "rm -rf " + self.dataDir
+        if os.system(cmd) != 0:
+            tdLog.exit(cmd)
+
+        cmd = "rm -rf " + self.logDir
+        if os.system(cmd) != 0:
+            tdLog.exit(cmd)
+
+        cmd = "rm -rf " + self.cfgDir
+        if os.system(cmd) != 0:
+            tdLog.exit(cmd)
+
+        cmd = "mkdir -p " + self.dataDir
+        if os.system(cmd) != 0:
+            tdLog.exit(cmd)
+
+        cmd = "mkdir -p " + self.logDir
+        if os.system(cmd) != 0:
+            tdLog.exit(cmd)
+
+        cmd = "mkdir -p " + self.cfgDir
+        if os.system(cmd) != 0:
+            tdLog.exit(cmd)
+
+        cmd = "touch " + self.cfgPath
+        if os.system(cmd) != 0:
+            tdLog.exit(cmd)
+
+        self.startIP()
+        self.cfg("masterIp", "192.168.0.1")
+        self.cfg("secondIp", "192.168.0.2")
+        self.cfg("publicIp", "192.168.0.%d" % (self.index))
+        self.cfg("internalIp", "192.168.0.%d" % (self.index))
+        self.cfg("privateIp", "192.168.0.%d" % (self.index))
+        self.cfg("dataDir", self.dataDir)
+        self.cfg("logDir", self.logDir)
+        self.cfg("numOfLogLines", "100000000")
+        self.cfg("mgmtEqualVnodeNum", "0")
+        self.cfg("clog", "1")
+        self.cfg("statusInterval", "1")
+        self.cfg("numOfTotalVnodes", "64")
+        self.cfg("numOfMPeers", "3")
+        self.cfg("numOfThreadsPerCore", "2.0")
+        self.cfg("monitor", "0")
+        self.cfg("maxVnodeConnections", "30000")
+        self.cfg("maxMgmtConnections", "30000")
+        self.cfg("maxMeterConnections", "30000")
+        self.cfg("maxShellConns", "30000")
+        self.cfg("locale", "en_US.UTF-8")
+        self.cfg("charset", "UTF-8")
+        self.cfg("asyncLog", "0")
+        self.cfg("anyIp", "0")
+        self.cfg("dDebugFlag", "135")
+        self.cfg("mDebugFlag", "135")
+        self.cfg("sdbDebugFlag", "135")
+        self.cfg("rpcDebugFlag", "135")
+        self.cfg("tmrDebugFlag", "131")
+        self.cfg("cDebugFlag", "135")
+        self.cfg("httpDebugFlag", "135")
+        self.cfg("monitorDebugFlag", "135")
+        self.cfg("udebugFlag", "135")
+        self.cfg("jnidebugFlag", "135")
+        self.cfg("qdebugFlag", "135")
+        self.deployed = 1
+        tdLog.debug(
+            "dnode:%d is deployed and configured by %s" %
+            (self.index, self.cfgPath))
+
+    def start(self):
+        binPath = os.path.dirname(os.path.realpath(__file__))
+        binPath = binPath + "/../../../debug/"
+        binPath = os.path.realpath(binPath)
+        binPath += "/build/bin/"
+
+        if self.deployed == 0:
+            tdLog.exit("dnode:%d is not deployed" % (self.index))
+        cmd = "nohup %staosd -c %s > /dev/null 2>&1 & " % (
+            binPath, self.cfgDir)
+        print(cmd)
+        if os.system(cmd) != 0:
+            tdLog.exit(cmd)
+        self.running = 1
+        tdLog.debug("dnode:%d is running with %s " % (self.index, cmd))
+
+        tdLog.debug("wait 2 seconds for the dnode:%d to start." % (self.index))
+        time.sleep(2)
+
+    def stop(self):
+        if self.running != 0:
+            cmd = "ps -ef|grep -w taosd | grep '%s' | grep -v grep | awk '{print $2}' && pkill -sigint taosd" % (
+                self.cfgDir)
+            if os.system(cmd) != 0:
+                tdLog.exit(cmd)
+            tdLog.debug("dnode:%d is stopped by kill -SIGINT" % (self.index))
+            tdLog.debug(
+                "wait 2 seconds for the dnode:%d to stop." %
+                (self.index))
+            time.sleep(2)
+
+    def forcestop(self):
+        if self.running != 0:
+            cmd = "ps -ef|grep -w taosd | grep '%s' | grep -v grep | awk '{print $2}' && pkill -sigkill taosd" % (
+                self.cfgDir)
+            if os.system(cmd) != 0:
+                tdLog.exit(cmd)
+            tdLog.debug("dnode:%d is stopped by kill -9" % (self.index))
+            tdLog.debug(
+                "wait 2 seconds for the dnode:%d to stop." %
+                (self.index))
+            time.sleep(2)
+
+    def startIP(self):
+        cmd = "sudo ifconfig lo:%d 192.168.0.%d up" % (self.index, self.index)
+        if os.system(cmd) != 0:
+            tdLog.exit(cmd)
+
+    def stopIP(self):
+        cmd = "sudo ifconfig lo:%d 192.168.0.%d down" % (
+            self.index, self.index)
+        if os.system(cmd) != 0:
+            tdLog.exit(cmd)
+
+    def cfg(self, option, value):
+        cmd = "echo '%s %s' >> %s" % (option, value, self.cfgPath)
+        if os.system(cmd) != 0:
+            tdLog.exit(cmd)
+
+    def getDnodeRootDir(self, index):
+        dnodeRootDir = "%s/sim/psim/dnode%d" % (self.path, index)
+        return dnodeRootDir
+
+    def getDnodesRootDir(self):
+        dnodesRootDir = "%s/sim/psim" % (self.path)
+        return dnodesRootDir
+
+
+class TDDnodes:
+    def __init__(self):
+        self.dnodes = []
+        self.dnodes.append(TDDnode(1))
+        self.dnodes.append(TDDnode(2))
+        self.dnodes.append(TDDnode(3))
+        self.dnodes.append(TDDnode(4))
+        self.dnodes.append(TDDnode(5))
+        self.dnodes.append(TDDnode(6))
+        self.dnodes.append(TDDnode(7))
+        self.dnodes.append(TDDnode(8))
+        self.dnodes.append(TDDnode(9))
+        self.dnodes.append(TDDnode(10))
+
+    def init(self, path):
+        cmd = "ps -ef|grep -w taosd | grep 'taosd' | grep -v grep | awk '{print $2}' && pkill -sigkill taosd"
+        os.system(cmd)
+
+        binPath = os.path.dirname(os.path.realpath(__file__))
+        binPath = binPath + "/../../../debug/"
+        tdLog.debug("binPath %s" % (binPath))
+        binPath = os.path.realpath(binPath)
+        tdLog.debug("binPath real path %s" % (binPath))
+
+        # cmd = "sudo cp %s/build/lib/libtaos.so /usr/local/lib/taos/" % (binPath)
+        # tdLog.debug(cmd)
+        # os.system(cmd)
+
+        # cmd = "sudo cp %s/build/bin/taos /usr/local/bin/taos/" % (binPath)
+        # if os.system(cmd) != 0 :
+        #  tdLog.exit(cmd)
+        # tdLog.debug("execute %s" % (cmd))
+
+        # cmd = "sudo cp %s/build/bin/taosd /usr/local/bin/taos/" % (binPath)
+        # if os.system(cmd) != 0 :
+        # tdLog.exit(cmd)
+        # tdLog.debug("execute %s" % (cmd))
+
+        if path == "":
+            # self.path = os.path.expanduser('~')
+            self.path = os.path.abspath(binPath + "../../")
+        else:
+            self.path = os.path.realpath(path)
+
+        for i in range(len(self.dnodes)):
+            self.dnodes[i].init(self.path)
+
+        self.sim = TDSimClient()
+        self.sim.init(self.path)
+        self.sim.deploy()
+
+    def deploy(self, index):
+        self.check(index)
+        self.dnodes[index - 1].deploy()
+
+    def cfg(self, index, option, value):
+        self.check(index)
+        self.dnodes[index - 1].cfg(option, value)
+
+    def start(self, index):
+        self.check(index)
+        self.dnodes[index - 1].start()
+
+    def stop(self, index):
+        self.check(index)
+        self.dnodes[index - 1].stop()
+
+    def forcestop(self, index):
+        self.check(index)
+        self.dnodes[index - 1].forcestop()
+
+    def startIP(self, index):
+        self.check(index)
+        self.dnodes[index - 1].startIP()
+
+    def stopIP(self, index):
+        self.check(index)
+        self.dnodes[index - 1].stopIP()
+
+    def check(self, index):
+        if index < 1 or index > 10:
+            tdLog.exit("index:%d should on a scale of [1, 10]" % (index))
+
+    def stopAll(self):
+        tdLog.debug("stop all dnodes")
+        for i in range(len(self.dnodes)):
+            self.dnodes[i].stop()
+
+        cmd = "sudo systemctl stop taosd"
+        os.system(cmd)
+        # if os.system(cmd) != 0 :
+        # tdLog.exit(cmd)
+        cmd = "ps -ef | grep -w taosd | grep 'dnode' | grep -v grep | awk '{print $2}' && sudo pkill -sigkill taosd"
+        os.system(cmd)
+        # if os.system(cmd) != 0 :
+        # tdLog.exit(cmd)
+
+    def getDnodesRootDir(self):
+        dnodesRootDir = "%s/sim" % (self.path)
+        return dnodesRootDir
+
+    def getSimCfgPath(self):
+        return self.sim.getCfgDir()
+
+
+tdDnodes = TDDnodes()
diff --git a/tests/pytest/util/log.py b/tests/pytest/util/log.py
new file mode 100644
index 0000000000..926e582448
--- /dev/null
+++ b/tests/pytest/util/log.py
@@ -0,0 +1,48 @@
+###################################################################
+#           Copyright (c) 2016 by TAOS Technologies, Inc.
+#                     All rights reserved.
+#
+#  This file is proprietary and confidential to TAOS Technologies.
+#  No part of this file may be reproduced, stored, transmitted,
+#  disclosed or used in any form or by any means other than as
+#  expressly provided by the written permission from Jianhui Tao
+#
+###################################################################
+
+# -*- coding: utf-8 -*-
+
+import sys
+import os
+import time
+import datetime
+
+
+class TDLog:
+    def __init__(self):
+        self.path = ""
+
+    def info(self, info):
+        print "%s %s" % (datetime.datetime.now(), info)
+
+    def sleep(self, sec):
+        print "%s sleep %d seconds" % (datetime.datetime.now(), sec)
+        time.sleep(sec)
+
+    def debug(self, err):
+        print "\033[1;36m%s %s\033[0m" % (datetime.datetime.now(), err)
+
+    def success(self, info):
+        print "\033[1;32m%s %s\033[0m" % (datetime.datetime.now(), info)
+
+    def notice(self, err):
+        print "\033[1;33m%s %s\033[0m" % (datetime.datetime.now(), err)
+
+    def exit(self, err):
+        print "\033[1;31m%s %s\033[0m" % (datetime.datetime.now(), err)
+        sys.exit(1)
+
+    def printNoPrefix(self, info):
+        print "\033[1;36m%s\033[0m" % (info)
+
+
+tdLog = TDLog()
diff --git a/tests/pytest/util/sql.py b/tests/pytest/util/sql.py
new file mode 100644
index 0000000000..b4ac845bc8
--- /dev/null
+++ b/tests/pytest/util/sql.py
@@ -0,0 +1,135 @@
+###################################################################
+#           Copyright (c) 2016 by TAOS Technologies, Inc.
+#                     All rights reserved.
+#
+#  This file is proprietary and confidential to TAOS Technologies.
+#  No part of this file may be reproduced, stored, transmitted,
+#  disclosed or used in any form or by any means other than as
+#  expressly provided by the written permission from Jianhui Tao
+#
+###################################################################
+
+# -*- coding: utf-8 -*-
+
+import sys
+import os
+import time
+import datetime
+from util.log import *
+
+
+class TDSql:
+    def __init__(self):
+        self.queryRows = 0
+        self.queryCols = 0
+        self.affectedRows = 0
+
+    def init(self, cursor):
+        self.cursor = cursor
+
+    def close(self):
+        self.cursor.close()
+
+    def prepare(self):
+        tdLog.info("prepare database:db")
+        self.cursor.execute('reset query cache')
+        self.cursor.execute('drop database if exists db')
+        self.cursor.execute('create database db')
+        self.cursor.execute('use db')
+
+    def error(self, sql):
+        expectErrNotOccured = True
+        try:
+            self.cursor.execute(sql)
+        except BaseException:
+            expectErrNotOccured = False
+        if expectErrNotOccured:
+            tdLog.exit("sql:%.40s, expect error not occured" % (sql))
+        else:
+            tdLog.info("sql:%.40s, expect error occured" % (sql))
+
+    def query(self, sql):
+        self.sql = sql
+        self.cursor.execute(sql)
+        self.queryResult = self.cursor.fetchall()
+        self.queryRows = len(self.queryResult)
+        self.queryCols = len(self.cursor.description)
+        # if self.queryRows == 1 and self.queryCols == 1:
+        #	tdLog.info("sql:%s, rows:%d cols:%d data:%s" % (self.sql, self.queryRows, self.queryCols, self.queryResult[0][0]))
+        # else:
+        #	tdLog.info("sql:%s, rows:%d cols:%d" % (self.sql, self.queryRows, self.queryCols))
+        return self.queryRows
+
+    def checkRows(self, expectRows):
+        if self.queryRows != expectRows:
+            tdLog.exit(
+                "sql:%.40s, queryRows:%d != expect:%d" %
+                (self.sql, self.queryRows, expectRows))
+        tdLog.info("sql:%.40s, queryRows:%d == expect:%d" %
+                   (self.sql, self.queryRows, expectRows))
+
+    def checkData(self, row, col, data):
+        if row < 0:
+            tdLog.exit(
+                "sql:%.40s, row:%d is smaller than zero" %
+                (self.sql, row))
+        if col < 0:
+            tdLog.exit(
+                "sql:%.40s, col:%d is smaller than zero" %
+                (self.sql, col))
+        if row >= self.queryRows:
+            tdLog.exit(
+                "sql:%.40s, row:%d is larger than queryRows:%d" %
+                (self.sql, row, self.queryRows))
+        if col >= self.queryCols:
+            tdLog.exit(
+                "sql:%.40s, col:%d is larger than queryRows:%d" %
+                (self.sql, col, self.queryCols))
+        if self.queryResult[row][col] != data:
+            tdLog.exit(
+                "sql:%.40s row:%d col:%d data:%s != expect:%s" %
+                (self.sql, row, col, self.queryResult[row][col], data))
+        tdLog.info("sql:%.40s, row:%d col:%d data:%s == expect:%d" %
+                   (self.sql, row, col, self.queryResult[row][col], data))
+
+    def getData(self, row, col):
+        if row < 0:
+            tdLog.exit(
+                "sql:%.40s, row:%d is smaller than zero" %
+                (self.sql, row))
+        if col < 0:
+            tdLog.exit(
+                "sql:%.40s, col:%d is smaller than zero" %
+                (self.sql, col))
+        if row >= self.queryRows:
+            tdLog.exit(
+                "sql:%.40s, row:%d is larger than queryRows:%d" %
+                (self.sql, row, self.queryRows))
+        if col >= self.queryCols:
+            tdLog.exit(
+                "sql:%.40s, col:%d is larger than queryRows:%d" %
+                (self.sql, col, self.queryCols))
+        return self.queryResult[row][col]
+
+    def executeTimes(self, sql, times):
+        for i in range(times):
+            try:
+                return self.cursor.execute(sql)
+            except BaseException:
+                time.sleep(1)
+                continue
+
+    def execute(self, sql):
+        self.sql = sql
+        self.affectedRows = self.cursor.execute(sql)
+        return self.affectedRows
+
+    def checkAffectedRows(self, expectAffectedRows):
+        if self.affectedRows != expectAffectedRows:
+            tdLog.exit("sql:%.40s, affectedRows:%d != expect:%d" %
+                       (self.sql, self.affectedRows, expectAffectedRows))
+        tdLog.info("sql:%.40s, affectedRows:%d == expect:%d" %
+                   (self.sql, self.affectedRows, expectAffectedRows))
+
+
+tdSql = TDSql()