diff --git a/src/inc/hash.h b/src/inc/hash.h
new file mode 100644
index 0000000000000000000000000000000000000000..54a43fb6ebc3f692c642e1270a948016b4244194
--- /dev/null
+++ b/src/inc/hash.h
@@ -0,0 +1,72 @@
+/*
+ * Copyright (c) 2019 TAOS Data, Inc. <jhtao@taosdata.com>
+ *
+ * This program is free software: you can use, redistribute, and/or modify
+ * it under the terms of the GNU Affero General Public License, version 3
+ * or later ("AGPL"), as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef TDENGINE_HASH_H
+#define TDENGINE_HASH_H
+
+#include "hashutil.h"
+
+#define HASH_MAX_CAPACITY (1024 * 1024 * 16)
+#define HASH_VALUE_IN_TRASH (-1)
+#define HASH_DEFAULT_LOAD_FACTOR (0.75)
+#define HASH_INDEX(v, c) ((v) & ((c)-1))
+
+typedef struct SHashNode {
+  char *key;  // null-terminated string
+  union {
+    struct SHashNode * prev;
+    struct SHashEntry *prev1;
+  };
+
+  struct SHashNode *next;
+  uint32_t          hashVal;  // the hash value of key, if hashVal == HASH_VALUE_IN_TRASH, this node is moved to trash
+  uint32_t          keyLen;   // length of the key
+  char              data[];
+} SHashNode;
+
+typedef struct SHashEntry {
+  SHashNode *next;
+  uint32_t   num;
+} SHashEntry;
+
+typedef struct HashObj {
+  SHashEntry **hashList;
+  uint32_t     capacity;
+  int          size;
+  _hash_fn_t   hashFp;
+  bool         multithreadSafe;  // enable lock
+
+#if defined LINUX
+  pthread_rwlock_t lock;
+#else
+  pthread_mutex_t lock;
+#endif
+
+} HashObj;
+
+void *taosInitHashTable(uint32_t capacity, _hash_fn_t fn, bool multithreadSafe);
+
+int32_t taosAddToHashTable(HashObj *pObj, const char *key, uint32_t keyLen, void *data, uint32_t size);
+void    taosDeleteFromHashTable(HashObj *pObj, const char *key, uint32_t keyLen);
+
+char *taosGetDataFromHash(HashObj *pObj, const char *key, uint32_t keyLen);
+
+void taosCleanUpHashTable(void *handle);
+
+int32_t taosGetHashMaxOverflowLength(HashObj *pObj);
+
+int32_t taosCheckHashTable(HashObj *pObj);
+
+#endif  // TDENGINE_HASH_H
diff --git a/src/inc/hashutil.h b/src/inc/hashutil.h
new file mode 100644
index 0000000000000000000000000000000000000000..063881b0b4338862d8552205b462b824b710e514
--- /dev/null
+++ b/src/inc/hashutil.h
@@ -0,0 +1,44 @@
+/*
+ * Copyright (c) 2019 TAOS Data, Inc. <jhtao@taosdata.com>
+ *
+ * This program is free software: you can use, redistribute, and/or modify
+ * it under the terms of the GNU Affero General Public License, version 3
+ * or later ("AGPL"), as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef TDENGINE_HASHUTIL_H
+#define TDENGINE_HASHUTIL_H
+
+
+typedef uint32_t (*_hash_fn_t)(const char *, uint32_t);
+
+/**
+ * murmur hash algorithm
+ * @key  usually string
+ * @len  key length
+ * @seed hash seed
+ * @out  an int32 value
+ */
+uint32_t MurmurHash3_32(const char *key, uint32_t len);
+
+/**
+ *
+ * @param key
+ * @param len
+ * @return
+ */
+uint32_t taosIntHash_32(const char *key, uint32_t len);
+
+
+uint32_t taosIntHash_64(const char *key, uint32_t len);
+
+_hash_fn_t taosGetDefaultHashFunction(int32_t type);
+
+#endif //TDENGINE_HASHUTIL_H
diff --git a/src/system/detail/src/vnodeQueryImpl.c b/src/system/detail/src/vnodeQueryImpl.c
index 25fb0374b8840f0aa1511b60bfbf10090dcece4b..7da2e60a385fa7b76ffa181dadd870f205fea683 100644
--- a/src/system/detail/src/vnodeQueryImpl.c
+++ b/src/system/detail/src/vnodeQueryImpl.c
@@ -17,6 +17,8 @@
 #include "taosmsg.h"
 #include "textbuffer.h"
 #include "ttime.h"
+#include "hash.h"
+#include "hashutil.h"
 
 #include "tinterpolation.h"
 #include "tscJoinProcess.h"
@@ -52,8 +54,6 @@ enum {
 static int32_t readDataFromDiskFile(int fd, SQInfo *pQInfo, SQueryFilesInfo *pQueryFile, char *buf, uint64_t offset,
                                     int32_t size);
 
-//__read_data_fn_t readDataFunctor[2] = {copyDataFromMMapBuffer, readDataFromDiskFile};
-
 static void    vnodeInitLoadCompBlockInfo(SQueryLoadCompBlockInfo *pCompBlockLoadInfo);
 static int32_t moveToNextBlock(SQueryRuntimeEnv *pRuntimeEnv, int32_t step, __block_search_fn_t searchFn,
                                bool loadData);
@@ -163,6 +163,30 @@ bool isGroupbyNormalCol(SSqlGroupbyExpr *pGroupbyExpr) {
   return false;
 }
 
+int16_t getGroupbyColumnType(SQuery* pQuery, SSqlGroupbyExpr *pGroupbyExpr) {
+  assert(pGroupbyExpr != NULL);
+  
+  int32_t colId = -2;
+  int16_t type = TSDB_DATA_TYPE_NULL;
+  
+  for(int32_t i = 0; i < pGroupbyExpr->numOfGroupCols; ++i) {
+    SColIndexEx *pColIndex = &pGroupbyExpr->columnInfo[i];
+    if (pColIndex->flag == TSDB_COL_NORMAL) {
+      colId = pColIndex->colId;
+      break;
+    }
+  }
+  
+  for(int32_t i = 0; i < pQuery->numOfCols; ++i) {
+    if (colId == pQuery->colList[i].data.colId) {
+      type = pQuery->colList[i].data.type;
+      break;
+    }
+  }
+  
+  return type;
+}
+
 bool isSelectivityWithTagsQuery(SQuery *pQuery) {
   bool    hasTags = false;
   int32_t numOfSelectivity = 0;
@@ -1446,7 +1470,7 @@ static bool needToLoadDataBlock(SQuery *pQuery, SField *pField, SQLFunctionCtx *
   return true;
 }
 
-static int32_t setGroupResultForKey(SQueryRuntimeEnv *pRuntimeEnv, char *pData, int16_t type, char *columnData) {
+static int32_t setGroupResultForKey(SQueryRuntimeEnv *pRuntimeEnv, char *pData, int16_t type, int16_t bytes) {
   SOutputRes *pOutputRes = NULL;
 
   // ignore the null value
@@ -1454,35 +1478,17 @@ static int32_t setGroupResultForKey(SQueryRuntimeEnv *pRuntimeEnv, char *pData,
     return -1;
   }
 
-  int64_t t = 0;
-  switch (type) {
-    case TSDB_DATA_TYPE_TINYINT:
-      t = GET_INT8_VAL(pData);
-      break;
-    case TSDB_DATA_TYPE_BIGINT:
-      t = GET_INT64_VAL(pData);
-      break;
-    case TSDB_DATA_TYPE_SMALLINT:
-      t = GET_INT16_VAL(pData);
-      break;
-    case TSDB_DATA_TYPE_INT:
-    default:
-      t = GET_INT32_VAL(pData);
-      break;
-  }
-
-  SOutputRes **p1 = (SOutputRes **)taosGetIntHashData(pRuntimeEnv->hashList, t);
+  SOutputRes **p1 = (SOutputRes **)taosGetDataFromHash(pRuntimeEnv->hashList, pData, bytes);
   if (p1 != NULL) {
     pOutputRes = *p1;
-  } else {
-    // more than the threshold number, discard data that are not belong to current groups
+  } else { // more than the threshold number, discard data that are not belong to current groups
     if (pRuntimeEnv->usedIndex >= 10000) {
       return -1;
     }
 
     // add a new result set for a new group
-    char *b = (char *)&pRuntimeEnv->pResult[pRuntimeEnv->usedIndex++];
-    pOutputRes = *(SOutputRes **)taosAddIntHash(pRuntimeEnv->hashList, t, (char *)&b);
+    pOutputRes = &pRuntimeEnv->pResult[pRuntimeEnv->usedIndex++];
+    taosAddToHashTable(pRuntimeEnv->hashList, pData, bytes, (char *)&pOutputRes, POINTER_BYTES);
   }
 
   setGroupOutputBuffer(pRuntimeEnv, pOutputRes);
@@ -1686,7 +1692,7 @@ static int32_t rowwiseApplyAllFunctions(SQueryRuntimeEnv *pRuntimeEnv, int32_t *
     if (groupbyStateValue) {
       char *stateVal = groupbyColumnData + bytes * offset;
 
-      int32_t ret = setGroupResultForKey(pRuntimeEnv, stateVal, type, groupbyColumnData);
+      int32_t ret = setGroupResultForKey(pRuntimeEnv, stateVal, type, bytes);
       if (ret != TSDB_CODE_SUCCESS) {  // null data, too many state code
         continue;
       }
@@ -2229,7 +2235,7 @@ static void teardownQueryRuntimeEnv(SQueryRuntimeEnv *pRuntimeEnv) {
 
   tfree(pRuntimeEnv->secondaryUnzipBuffer);
 
-  taosCleanUpIntHash(pRuntimeEnv->hashList);
+  taosCleanUpHashTable(pRuntimeEnv->hashList);
 
   if (pRuntimeEnv->pCtx != NULL) {
     for (int32_t i = 0; i < pRuntimeEnv->pQuery->numOfOutputCols; ++i) {
@@ -3742,9 +3748,11 @@ int32_t vnodeQuerySingleMeterPrepare(SQInfo *pQInfo, SMeterObj *pMeterObj, SMete
   // check data in file or cache
   bool dataInCache = true;
   bool dataInDisk = true;
-  pSupporter->runtimeEnv.pQuery = pQuery;
+  
+  SQueryRuntimeEnv* pRuntimeEnv = &pSupporter->runtimeEnv;
+  pRuntimeEnv->pQuery = pQuery;
 
-  vnodeCheckIfDataExists(&pSupporter->runtimeEnv, pMeterObj, &dataInDisk, &dataInCache);
+  vnodeCheckIfDataExists(pRuntimeEnv, pMeterObj, &dataInDisk, &dataInCache);
 
   /* data in file or cache is not qualified for the query. abort */
   if (!(dataInCache || dataInDisk)) {
@@ -3755,11 +3763,11 @@ int32_t vnodeQuerySingleMeterPrepare(SQInfo *pQInfo, SMeterObj *pMeterObj, SMete
     return TSDB_CODE_SUCCESS;
   }
 
-  pSupporter->runtimeEnv.pTSBuf = param;
-  pSupporter->runtimeEnv.cur.vnodeIndex = -1;
+  pRuntimeEnv->pTSBuf = param;
+  pRuntimeEnv->cur.vnodeIndex = -1;
   if (param != NULL) {
-    int16_t order = (pQuery->order.order == pSupporter->runtimeEnv.pTSBuf->tsOrder) ? TSQL_SO_ASC : TSQL_SO_DESC;
-    tsBufSetTraverseOrder(pSupporter->runtimeEnv.pTSBuf, order);
+    int16_t order = (pQuery->order.order == pRuntimeEnv->pTSBuf->tsOrder) ? TSQL_SO_ASC : TSQL_SO_DESC;
+    tsBufSetTraverseOrder(pRuntimeEnv->pTSBuf, order);
   }
 
   // create runtime environment
@@ -3775,9 +3783,13 @@ int32_t vnodeQuerySingleMeterPrepare(SQInfo *pQInfo, SMeterObj *pMeterObj, SMete
       return ret;
     }
 
-    pSupporter->runtimeEnv.hashList = taosInitIntHash(10039, sizeof(void *), taosHashInt);
-    pSupporter->runtimeEnv.usedIndex = 0;
-    pSupporter->runtimeEnv.pResult = pSupporter->pResult;
+    int16_t type = getGroupbyColumnType(pQuery, pQuery->pGroupbyExpr);
+    _hash_fn_t fn = taosGetDefaultHashFunction(type);
+    
+    pRuntimeEnv->hashList = taosInitHashTable(10039, fn, false);
+    
+    pRuntimeEnv->usedIndex = 0;
+    pRuntimeEnv->pResult = pSupporter->pResult;
   }
 
   // in case of last_row query, we set the query timestamp to pMeterObj->lastKey;
@@ -3820,7 +3832,7 @@ int32_t vnodeQuerySingleMeterPrepare(SQInfo *pQInfo, SMeterObj *pMeterObj, SMete
 
   int64_t rs = taosGetIntervalStartTimestamp(pSupporter->rawSKey, pQuery->nAggTimeInterval, pQuery->intervalTimeUnit,
                                              pQuery->precision);
-  taosInitInterpoInfo(&pSupporter->runtimeEnv.interpoInfo, pQuery->order.order, rs, 0, 0);
+  taosInitInterpoInfo(&pRuntimeEnv->interpoInfo, pQuery->order.order, rs, 0, 0);
   allocMemForInterpo(pSupporter, pQuery, pMeterObj);
 
   if (!isPointInterpoQuery(pQuery)) {
@@ -3843,9 +3855,9 @@ void vnodeQueryFreeQInfoEx(SQInfo *pQInfo) {
   teardownQueryRuntimeEnv(&pSupporter->runtimeEnv);
   tfree(pSupporter->pMeterSidExtInfo);
 
-  if (pSupporter->pMeterObj != NULL) {
-    taosCleanUpIntHash(pSupporter->pMeterObj);
-    pSupporter->pMeterObj = NULL;
+  if (pSupporter->pMetersHashTable != NULL) {
+    taosCleanUpHashTable(pSupporter->pMetersHashTable);
+    pSupporter->pMetersHashTable = NULL;
   }
 
   if (pSupporter->pSidSet != NULL || isGroupbyNormalCol(pQInfo->query.pGroupbyExpr)) {
@@ -3904,10 +3916,11 @@ int32_t vnodeMultiMeterQueryPrepare(SQInfo *pQInfo, SQuery *pQuery, void *param)
   pQuery->pointsRead = 0;
 
   changeExecuteScanOrder(pQuery, true);
+  SQueryRuntimeEnv* pRuntimeEnv = &pSupporter->runtimeEnv;
 
-  doInitQueryFileInfoFD(&pSupporter->runtimeEnv.vnodeFileInfo);
-  vnodeInitDataBlockInfo(&pSupporter->runtimeEnv.loadBlockInfo);
-  vnodeInitLoadCompBlockInfo(&pSupporter->runtimeEnv.loadCompBlockInfo);
+  doInitQueryFileInfoFD(&pRuntimeEnv->vnodeFileInfo);
+  vnodeInitDataBlockInfo(&pRuntimeEnv->loadBlockInfo);
+  vnodeInitLoadCompBlockInfo(&pRuntimeEnv->loadCompBlockInfo);
 
   /*
    * since we employ the output control mechanism in main loop.
@@ -3929,15 +3942,15 @@ int32_t vnodeMultiMeterQueryPrepare(SQInfo *pQInfo, SQuery *pQuery, void *param)
   }
 
   // get one queried meter
-  SMeterObj *pMeter = getMeterObj(pSupporter->pMeterObj, pSupporter->pSidSet->pSids[0]->sid);
+  SMeterObj *pMeter = getMeterObj(pSupporter->pMetersHashTable, pSupporter->pSidSet->pSids[0]->sid);
 
-  pSupporter->runtimeEnv.pTSBuf = param;
-  pSupporter->runtimeEnv.cur.vnodeIndex = -1;
+  pRuntimeEnv->pTSBuf = param;
+  pRuntimeEnv->cur.vnodeIndex = -1;
 
   // set the ts-comp file traverse order
   if (param != NULL) {
-    int16_t order = (pQuery->order.order == pSupporter->runtimeEnv.pTSBuf->tsOrder) ? TSQL_SO_ASC : TSQL_SO_DESC;
-    tsBufSetTraverseOrder(pSupporter->runtimeEnv.pTSBuf, order);
+    int16_t order = (pQuery->order.order == pRuntimeEnv->pTSBuf->tsOrder) ? TSQL_SO_ASC : TSQL_SO_DESC;
+    tsBufSetTraverseOrder(pRuntimeEnv->pTSBuf, order);
   }
 
   int32_t ret = setupQueryRuntimeEnv(pMeter, pQuery, &pSupporter->runtimeEnv, pTagSchema, TSQL_SO_ASC, true);
@@ -3953,9 +3966,9 @@ int32_t vnodeMultiMeterQueryPrepare(SQInfo *pQInfo, SQuery *pQuery, void *param)
   }
 
   if (isGroupbyNormalCol(pQuery->pGroupbyExpr)) {  // group by columns not tags;
-    pSupporter->runtimeEnv.hashList = taosInitIntHash(10039, sizeof(void *), taosHashInt);
-    pSupporter->runtimeEnv.usedIndex = 0;
-    pSupporter->runtimeEnv.pResult = pSupporter->pResult;
+    pRuntimeEnv->hashList = taosInitHashTable(10039, taosIntHash_64, false);
+    pRuntimeEnv->usedIndex = 0;
+    pRuntimeEnv->pResult = pSupporter->pResult;
   }
 
   if (pQuery->nAggTimeInterval != 0) {
@@ -3976,7 +3989,7 @@ int32_t vnodeMultiMeterQueryPrepare(SQInfo *pQInfo, SQuery *pQuery, void *param)
       return TSDB_CODE_SERV_NO_DISKSPACE;
     }
 
-    pSupporter->runtimeEnv.numOfRowsPerPage = (DEFAULT_INTERN_BUF_SIZE - sizeof(tFilePage)) / pQuery->rowSize;
+    pRuntimeEnv->numOfRowsPerPage = (DEFAULT_INTERN_BUF_SIZE - sizeof(tFilePage)) / pQuery->rowSize;
     pSupporter->lastPageId = -1;
     pSupporter->bufSize = pSupporter->numOfPages * DEFAULT_INTERN_BUF_SIZE;
 
@@ -3995,7 +4008,7 @@ int32_t vnodeMultiMeterQueryPrepare(SQInfo *pQInfo, SQuery *pQuery, void *param)
 
   TSKEY revisedStime = taosGetIntervalStartTimestamp(pSupporter->rawSKey, pQuery->nAggTimeInterval,
                                                      pQuery->intervalTimeUnit, pQuery->precision);
-  taosInitInterpoInfo(&pSupporter->runtimeEnv.interpoInfo, pQuery->order.order, revisedStime, 0, 0);
+  taosInitInterpoInfo(&pRuntimeEnv->interpoInfo, pQuery->order.order, revisedStime, 0, 0);
 
   return TSDB_CODE_SUCCESS;
 }
@@ -4014,7 +4027,7 @@ void vnodeDecMeterRefcnt(SQInfo *pQInfo) {
   } else {
     int32_t num = 0;
     for (int32_t i = 0; i < pSupporter->numOfMeters; ++i) {
-      SMeterObj *pMeter = getMeterObj(pSupporter->pMeterObj, pSupporter->pSidSet->pSids[i]->sid);
+      SMeterObj *pMeter = getMeterObj(pSupporter->pMetersHashTable, pSupporter->pSidSet->pSids[i]->sid);
       atomic_fetch_sub_32(&(pMeter->numOfQueries), 1);
 
       if (pMeter->numOfQueries > 0) {
@@ -5060,7 +5073,7 @@ int32_t doCloseAllOpenedResults(SMeterQuerySupportObj *pSupporter) {
       if (pMeterInfo[i].pMeterQInfo != NULL && pMeterInfo[i].pMeterQInfo->lastResRows > 0) {
         int32_t index = pMeterInfo[i].meterOrderIdx;
 
-        pRuntimeEnv->pMeterObj = getMeterObj(pSupporter->pMeterObj, pSupporter->pSidSet->pSids[index]->sid);
+        pRuntimeEnv->pMeterObj = getMeterObj(pSupporter->pMetersHashTable, pSupporter->pSidSet->pSids[index]->sid);
         assert(pRuntimeEnv->pMeterObj == pMeterInfo[i].pMeterObj);
 
         int32_t ret = setIntervalQueryExecutionContext(pSupporter, i, pMeterInfo[i].pMeterQInfo);
@@ -5666,7 +5679,7 @@ int32_t vnodeFilterQualifiedMeters(SQInfo *pQInfo, int32_t vid, tSidSet *pSidSet
   TSKEY   skey, ekey;
 
   for (int32_t i = 0; i < pSidSet->numOfSids; ++i) {  // load all meter meta info
-    SMeterObj *pMeterObj = getMeterObj(pSupporter->pMeterObj, pMeterSidExtInfo[i]->sid);
+    SMeterObj *pMeterObj = getMeterObj(pSupporter->pMetersHashTable, pMeterSidExtInfo[i]->sid);
     if (pMeterObj == NULL) {
       dError("QInfo:%p failed to find required sid:%d", pQInfo, pMeterSidExtInfo[i]->sid);
       continue;
diff --git a/src/system/detail/src/vnodeQueryProcess.c b/src/system/detail/src/vnodeQueryProcess.c
index c69b27537e82fc7a58aff764276bc8d932f18a1c..da17b0dd189a7d5f09762ed267462f0b8efdfccc 100644
--- a/src/system/detail/src/vnodeQueryProcess.c
+++ b/src/system/detail/src/vnodeQueryProcess.c
@@ -92,7 +92,7 @@ static SMeterDataInfo *queryOnMultiDataCache(SQInfo *pQInfo, SMeterDataInfo *pMe
 
   SMeterSidExtInfo **pMeterSidExtInfo = pSupporter->pMeterSidExtInfo;
 
-  SMeterObj *pTempMeterObj = getMeterObj(pSupporter->pMeterObj, pMeterSidExtInfo[0]->sid);
+  SMeterObj *pTempMeterObj = getMeterObj(pSupporter->pMetersHashTable, pMeterSidExtInfo[0]->sid);
   assert(pTempMeterObj != NULL);
 
   __block_search_fn_t searchFn = vnodeSearchKeyFunc[pTempMeterObj->searchAlgorithm];
@@ -111,7 +111,7 @@ static SMeterDataInfo *queryOnMultiDataCache(SQInfo *pQInfo, SMeterDataInfo *pMe
     }
 
     for (int32_t k = start; k <= end; ++k) {
-      SMeterObj *pMeterObj = getMeterObj(pSupporter->pMeterObj, pMeterSidExtInfo[k]->sid);
+      SMeterObj *pMeterObj = getMeterObj(pSupporter->pMetersHashTable, pMeterSidExtInfo[k]->sid);
       if (pMeterObj == NULL) {
         dError("QInfo:%p failed to find meterId:%d, continue", pQInfo, pMeterSidExtInfo[k]->sid);
         continue;
@@ -266,7 +266,7 @@ static SMeterDataInfo *queryOnMultiDataFiles(SQInfo *pQInfo, SMeterDataInfo *pMe
   SMeterDataBlockInfoEx *pDataBlockInfoEx = NULL;
   int32_t                nAllocBlocksInfoSize = 0;
 
-  SMeterObj *         pTempMeter = getMeterObj(pSupporter->pMeterObj, pSupporter->pMeterSidExtInfo[0]->sid);
+  SMeterObj *         pTempMeter = getMeterObj(pSupporter->pMetersHashTable, pSupporter->pMeterSidExtInfo[0]->sid);
   __block_search_fn_t searchFn = vnodeSearchKeyFunc[pTempMeter->searchAlgorithm];
 
   int32_t vnodeId = pTempMeter->vnode;
@@ -475,7 +475,7 @@ static bool multimeterMultioutputHelper(SQInfo *pQInfo, bool *dataInDisk, bool *
 
   setQueryStatus(pQuery, QUERY_NOT_COMPLETED);
 
-  SMeterObj *pMeterObj = getMeterObj(pSupporter->pMeterObj, pMeterSidExtInfo[index]->sid);
+  SMeterObj *pMeterObj = getMeterObj(pSupporter->pMetersHashTable, pMeterSidExtInfo[index]->sid);
   if (pMeterObj == NULL) {
     dError("QInfo:%p do not find required meter id: %d, all meterObjs id is:", pQInfo, pMeterSidExtInfo[index]->sid);
     return false;
@@ -576,7 +576,7 @@ static void vnodeMultiMeterMultiOutputProcessor(SQInfo *pQInfo) {
   SQuery * pQuery = &pQInfo->query;
   tSidSet *pSids = pSupporter->pSidSet;
 
-  SMeterObj *pOneMeter = getMeterObj(pSupporter->pMeterObj, pMeterSidExtInfo[0]->sid);
+  SMeterObj *pOneMeter = getMeterObj(pSupporter->pMetersHashTable, pMeterSidExtInfo[0]->sid);
 
   resetCtxOutputBuf(pRuntimeEnv);
 
@@ -604,7 +604,7 @@ static void vnodeMultiMeterMultiOutputProcessor(SQInfo *pQInfo) {
           }
 
           // get the last key of meters that belongs to this group
-          SMeterObj *pMeterObj = getMeterObj(pSupporter->pMeterObj, pMeterSidExtInfo[k]->sid);
+          SMeterObj *pMeterObj = getMeterObj(pSupporter->pMetersHashTable, pMeterSidExtInfo[k]->sid);
           if (pMeterObj != NULL) {
             if (key < pMeterObj->lastKey) {
               key = pMeterObj->lastKey;
@@ -674,10 +674,10 @@ static void vnodeMultiMeterMultiOutputProcessor(SQInfo *pQInfo) {
     }
 
     pRuntimeEnv->usedIndex = 0;
-    taosCleanUpIntHash(pRuntimeEnv->hashList);
+    taosCleanUpHashTable(pRuntimeEnv->hashList);
 
     int32_t primeHashSlot = 10039;
-    pRuntimeEnv->hashList = taosInitIntHash(primeHashSlot, POINTER_BYTES, taosHashInt);
+    pRuntimeEnv->hashList = taosInitHashTable(primeHashSlot, taosIntHash_32, false);
 
     while (pSupporter->meterIdx < pSupporter->numOfMeters) {
       int32_t k = pSupporter->meterIdx;
diff --git a/src/system/detail/src/vnodeRead.c b/src/system/detail/src/vnodeRead.c
index bbd3e9465c32174566f08b809545ae4b5d7e5f65..a76faf8a8d1ebfed7f7dd55f9c4facf768710581 100644
--- a/src/system/detail/src/vnodeRead.c
+++ b/src/system/detail/src/vnodeRead.c
@@ -25,6 +25,8 @@
 #include "vnode.h"
 #include "vnodeRead.h"
 #include "vnodeUtil.h"
+#include "hash.h"
+#include "hashutil.h"
 
 int (*pQueryFunc[])(SMeterObj *, SQuery *) = {vnodeQueryFromCache, vnodeQueryFromFile};
 
@@ -655,8 +657,9 @@ void *vnodeQueryOnSingleTable(SMeterObj **pMetersObj, SSqlGroupbyExpr *pGroupbyE
     SMeterQuerySupportObj *pSupporter = (SMeterQuerySupportObj *)calloc(1, sizeof(SMeterQuerySupportObj));
     pSupporter->numOfMeters = 1;
 
-    pSupporter->pMeterObj = taosInitIntHash(pSupporter->numOfMeters, POINTER_BYTES, taosHashInt);
-    taosAddIntHash(pSupporter->pMeterObj, pMetersObj[0]->sid, (char *)&pMetersObj[0]);
+    pSupporter->pMetersHashTable = taosInitHashTable(pSupporter->numOfMeters, taosIntHash_32, false);
+    taosAddToHashTable(pSupporter->pMetersHashTable, (const char*) &pMetersObj[0]->sid, sizeof(pMeterObj[0].sid),
+        (char *)&pMetersObj[0], POINTER_BYTES);
 
     pSupporter->pSidSet = NULL;
     pSupporter->subgroupIdx = -1;
@@ -748,9 +751,10 @@ void *vnodeQueryOnMultiMeters(SMeterObj **pMetersObj, SSqlGroupbyExpr *pGroupbyE
   SMeterQuerySupportObj *pSupporter = (SMeterQuerySupportObj *)calloc(1, sizeof(SMeterQuerySupportObj));
   pSupporter->numOfMeters = pQueryMsg->numOfSids;
 
-  pSupporter->pMeterObj = taosInitIntHash(pSupporter->numOfMeters, POINTER_BYTES, taosHashInt);
+  pSupporter->pMetersHashTable = taosInitHashTable(pSupporter->numOfMeters, taosIntHash_32, false);
   for (int32_t i = 0; i < pSupporter->numOfMeters; ++i) {
-    taosAddIntHash(pSupporter->pMeterObj, pMetersObj[i]->sid, (char *)&pMetersObj[i]);
+    taosAddToHashTable(pSupporter->pMetersHashTable, (const char*) &pMetersObj[i]->sid, sizeof(pMetersObj[i]->sid), (char *)&pMetersObj[i],
+                       POINTER_BYTES);
   }
 
   pSupporter->pMeterSidExtInfo = (SMeterSidExtInfo **)pQueryMsg->pSidExtInfo;
diff --git a/src/system/detail/src/vnodeShell.c b/src/system/detail/src/vnodeShell.c
index ce1cabe1415c37173b3db1a1d3cc138b7cbef6f7..8a15cc896051a2459d4fd874866109025e44fb6d 100644
--- a/src/system/detail/src/vnodeShell.c
+++ b/src/system/detail/src/vnodeShell.c
@@ -472,7 +472,8 @@ void vnodeExecuteRetrieveReq(SSchedMsg *pSched) {
 
   assert(code != TSDB_CODE_ACTION_IN_PROGRESS);
   
-  if (numOfRows == 0 && (pRetrieve->qhandle == (uint64_t)pObj->qhandle) && (code != TSDB_CODE_ACTION_IN_PROGRESS)) {
+  if (numOfRows == 0 && (pRetrieve->qhandle == (uint64_t)pObj->qhandle) && (code != TSDB_CODE_ACTION_IN_PROGRESS) &&
+     pRetrieve->qhandle != 0) {
     dTrace("QInfo:%p %s free qhandle code:%d", pObj->qhandle, __FUNCTION__, code);
     vnodeDecRefCount(pObj->qhandle);
     pObj->qhandle = NULL;
diff --git a/src/util/src/hash.c b/src/util/src/hash.c
new file mode 100644
index 0000000000000000000000000000000000000000..a0ca4a96bbf5e8ca07e6cae063d8423af16d2a9c
--- /dev/null
+++ b/src/util/src/hash.c
@@ -0,0 +1,537 @@
+/*
+ * Copyright (c) 2019 TAOS Data, Inc. <jhtao@taosdata.com>
+ *
+ * This program is free software: you can use, redistribute, and/or modify
+ * it under the terms of the GNU Affero General Public License, version 3
+ * or later ("AGPL"), as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "os.h"
+
+#include "hash.h"
+#include "tlog.h"
+#include "ttime.h"
+#include "tutil.h"
+
+static FORCE_INLINE void __wr_lock(void *lock) {
+#if defined              LINUX
+  pthread_rwlock_wrlock(lock);
+#else
+  pthread_mutex_lock(lock);
+#endif
+}
+
+static FORCE_INLINE void __rd_lock(void *lock) {
+#if defined              LINUX
+  pthread_rwlock_rdlock(lock);
+#else
+  pthread_mutex_lock(lock);
+#endif
+}
+
+static FORCE_INLINE void __unlock(void *lock) {
+#if defined              LINUX
+  pthread_rwlock_unlock(lock);
+#else
+  pthread_mutex_unlock(lock);
+#endif
+}
+
+static FORCE_INLINE int32_t __lock_init(void *lock) {
+#if defined                 LINUX
+  return pthread_rwlock_init(lock, NULL);
+#else
+  return pthread_mutex_init(lock, NULL);
+#endif
+}
+
+static FORCE_INLINE void __lock_destroy(void *lock) {
+#if defined              LINUX
+  pthread_rwlock_destroy(lock);
+#else
+  pthread_mutex_destroy(lock);
+#endif
+}
+
+static FORCE_INLINE int32_t taosHashCapacity(int32_t length) {
+  int32_t len = MIN(length, HASH_MAX_CAPACITY);
+
+  uint32_t i = 4;
+  while (i < len) i = (i << 1U);
+  return i;
+}
+
+/**
+ * hash key function
+ *
+ * @param key    key string
+ * @param len    length of key
+ * @return       hash value
+ */
+static FORCE_INLINE uint32_t taosHashKey(const char *key, uint32_t len) { return MurmurHash3_32(key, len); }
+
+/**
+ * inplace update node in hash table
+ * @param pObj      hash table object
+ * @param pNode     data node
+ */
+static void doUpdateHashTable(HashObj *pObj, SHashNode *pNode) {
+  if (pNode->prev1) {
+    pNode->prev1->next = pNode;
+  }
+
+  if (pNode->next) {
+    (pNode->next)->prev = pNode;
+  }
+
+  pTrace("key:%s %p update hash table", pNode->key, pNode);
+}
+
+/**
+ * get SHashNode from hashlist, nodes from trash are not included.
+ * @param pObj      Cache objection
+ * @param key       key for hash
+ * @param keyLen    key length
+ * @return
+ */
+static SHashNode *doGetNodeFromHashTable(HashObj *pObj, const char *key, uint32_t keyLen, uint32_t *hashVal) {
+  uint32_t hash = (*pObj->hashFp)(key, keyLen);
+
+  int32_t     slot = HASH_INDEX(hash, pObj->capacity);
+  SHashEntry *pEntry = pObj->hashList[slot];
+
+  SHashNode *pNode = pEntry->next;
+  while (pNode) {
+    if ((pNode->keyLen == keyLen) && (memcmp(pNode->key, key, keyLen) == 0)) {
+      break;
+    }
+
+    pNode = pNode->next;
+  }
+
+  if (pNode) {
+    assert(HASH_INDEX(pNode->hashVal, pObj->capacity) == slot);
+  }
+
+  // return the calculated hash value, to avoid calculating it again in other functions
+  if (hashVal != NULL) {
+    *hashVal = hash;
+  }
+
+  return pNode;
+}
+
+/**
+ * resize the hash list if the threshold is reached
+ *
+ * @param pObj
+ */
+static void taosHashTableResize(HashObj *pObj) {
+  if (pObj->size < pObj->capacity * HASH_DEFAULT_LOAD_FACTOR) {
+    return;
+  }
+
+  // double the original capacity
+  SHashNode *pNode = NULL;
+  SHashNode *pNext = NULL;
+
+  int32_t newSize = pObj->capacity << 1U;
+  if (newSize > HASH_MAX_CAPACITY) {
+    pTrace("current capacity:%d, maximum capacity:%d, no resize applied due to limitation is reached", pObj->capacity,
+           HASH_MAX_CAPACITY);
+    return;
+  }
+
+  int64_t st = taosGetTimestampUs();
+
+  SHashEntry **pNewEntry = realloc(pObj->hashList, sizeof(SHashEntry*) * newSize);
+  if (pNewEntry == NULL) {
+    pTrace("cache resize failed due to out of memory, capacity remain:%d", pObj->capacity);
+    return;
+  }
+
+  pObj->hashList = pNewEntry;
+  for(int32_t i = pObj->capacity; i < newSize; ++i) {
+    pObj->hashList[i] = calloc(1, sizeof(SHashEntry));
+  }
+  
+  pObj->capacity = newSize;
+
+  for (int32_t i = 0; i < pObj->capacity; ++i) {
+    SHashEntry *pEntry = pObj->hashList[i];
+
+    pNode = pEntry->next;
+    if (pNode != NULL) {
+      assert(pNode->prev1 == pEntry && pEntry->num > 0);
+    }
+    
+    while (pNode) {
+      int32_t j = HASH_INDEX(pNode->hashVal, pObj->capacity);
+      if (j == i) {  // this key resides in the same slot, no need to relocate it
+        pNode = pNode->next;
+      } else {
+        pNext = pNode->next;
+
+        // remove from current slot
+        assert(pNode->prev1 != NULL);
+        
+        if (pNode->prev1 == pEntry) { // first node of the overflow linked list
+          pEntry->next = pNode->next;
+        } else {
+          pNode->prev->next = pNode->next;
+        }
+        
+        pEntry->num--;
+        assert(pEntry->num >= 0);
+
+        if (pNode->next != NULL) {
+          (pNode->next)->prev = pNode->prev;
+        }
+
+        // added into new slot
+        pNode->next = NULL;
+        pNode->prev1 = NULL;
+
+        SHashEntry *pNewIndexEntry = pObj->hashList[j];
+
+        if (pNewIndexEntry->next != NULL) {
+          assert(pNewIndexEntry->next->prev1 == pNewIndexEntry);
+          
+          pNewIndexEntry->next->prev = pNode;
+        }
+  
+        pNode->next = pNewIndexEntry->next;
+        pNode->prev1 = pNewIndexEntry;
+        
+        pNewIndexEntry->next = pNode;
+        pNewIndexEntry->num++;
+
+        // continue
+        pNode = pNext;
+      }
+    }
+  }
+
+  int64_t et = taosGetTimestampUs();
+
+  pTrace("hash table resize completed, new capacity:%d, load factor:%f, elapsed time:%fms", pObj->capacity,
+         ((double)pObj->size) / pObj->capacity, (et - st) / 1000.0);
+}
+
+/**
+ * @param capacity maximum slots available for hash elements
+ * @param fn       hash function
+ * @return
+ */
+void *taosInitHashTable(uint32_t capacity, _hash_fn_t fn, bool multithreadSafe) {
+  if (capacity == 0 || fn == NULL) {
+    return NULL;
+  }
+
+  HashObj *pObj = (HashObj *)calloc(1, sizeof(HashObj));
+  if (pObj == NULL) {
+    pError("failed to allocate memory, reason:%s", strerror(errno));
+    return NULL;
+  }
+
+  // the max slots is not defined by user
+  pObj->capacity = taosHashCapacity(capacity);
+  assert((pObj->capacity & (pObj->capacity - 1)) == 0);
+
+  pObj->hashFp = fn;
+
+  pObj->hashList = (SHashEntry **)calloc(pObj->capacity, sizeof(SHashEntry*));
+  if (pObj->hashList == NULL) {
+    free(pObj);
+    pError("failed to allocate memory, reason:%s", strerror(errno));
+    return NULL;
+  }
+  
+  for(int32_t i = 0; i < pObj->capacity; ++i) {
+    pObj->hashList[i] = calloc(1, sizeof(SHashEntry));
+  }
+
+  if (multithreadSafe && (__lock_init(pObj) != 0)) {
+    free(pObj->hashList);
+    free(pObj);
+
+    pError("failed to init lock, reason:%s", strerror(errno));
+    return NULL;
+  }
+
+  return (void *)pObj;
+}
+
+/**
+ * @param key      key of object for hash, usually a null-terminated string
+ * @param keyLen   length of key
+ * @param pData    actually data. required a consecutive memory block, no pointer is allowed
+ *                 in pData. Pointer copy causes memory access error.
+ * @param size     size of block
+ * @return         SHashNode
+ */
+static SHashNode *doCreateHashNode(const char *key, uint32_t keyLen, const char *pData, size_t dataSize,
+                                   uint32_t hashVal) {
+  size_t totalSize = dataSize + sizeof(SHashNode) + keyLen;
+
+  SHashNode *pNewNode = calloc(1, totalSize);
+  if (pNewNode == NULL) {
+    pError("failed to allocate memory, reason:%s", strerror(errno));
+    return NULL;
+  }
+
+  memcpy(pNewNode->data, pData, dataSize);
+
+  pNewNode->key = pNewNode->data + dataSize;
+  memcpy(pNewNode->key, key, keyLen);
+  pNewNode->keyLen = keyLen;
+
+  pNewNode->hashVal = hashVal;
+
+  return pNewNode;
+}
+
+static SHashNode *doUpdateHashNode(SHashNode *pNode, const char *key, uint32_t keyLen, const char *pData,
+                                   size_t dataSize) {
+  size_t size = dataSize + sizeof(SHashNode) + keyLen;
+
+  SHashNode *pNewNode = (SHashNode *)realloc(pNode, size);
+  if (pNewNode == NULL) {
+    return NULL;
+  }
+
+  memcpy(pNewNode->data, pData, dataSize);
+
+  pNewNode->key = pNewNode->data + dataSize;
+
+  assert(memcmp(pNewNode->key, key, keyLen) == 0 && keyLen == pNewNode->keyLen);
+
+  memcpy(pNewNode->key, key, keyLen);
+  return pNewNode;
+}
+
+/**
+ * insert the hash node at the front of the linked list
+ *
+ * @param pObj
+ * @param pNode
+ */
+static void doAddToHashTable(HashObj *pObj, SHashNode *pNode) {
+  assert(pNode != NULL);
+
+  int32_t     index = HASH_INDEX(pNode->hashVal, pObj->capacity);
+  SHashEntry *pEntry = pObj->hashList[index];
+  
+  pNode->next = pEntry->next;
+
+  if (pEntry->next) {
+    pEntry->next->prev = pNode;
+  }
+
+  pEntry->next = pNode;
+  pNode->prev1 = pEntry;
+  
+  pEntry->num++;
+
+  pObj->size++;
+  
+  char key[512] = {0};
+  memcpy(key, pNode->key, MIN(512, pNode->keyLen));
+  
+  pTrace("key:%s %p add to hash table", key, pNode);
+}
+
+/**
+ * add data node into hash table
+ * @param pObj    hash object
+ * @param pNode   hash node
+ */
+int32_t taosAddToHashTable(HashObj *pObj, const char *key, uint32_t keyLen, void *data, uint32_t size) {
+  if (pObj->multithreadSafe) {
+    __wr_lock(&pObj->lock);
+  }
+
+  uint32_t   hashVal = 0;
+  SHashNode *pNode = doGetNodeFromHashTable(pObj, key, keyLen, &hashVal);
+
+  if (pNode == NULL) {  // no data in hash table with the specified key, add it into hash table
+    taosHashTableResize(pObj);
+
+    SHashNode *pNewNode = doCreateHashNode(key, keyLen, data, size, hashVal);
+    if (pNewNode == NULL) {
+      if (pObj->multithreadSafe) {
+        __unlock(&pObj->lock);
+      }
+
+      return -1;
+    }
+
+    doAddToHashTable(pObj, pNewNode);
+  } else {
+    SHashNode *pNewNode = doUpdateHashNode(pNode, key, keyLen, data, size);
+    if (pNewNode == NULL) {
+      if (pObj->multithreadSafe) {
+        __unlock(&pObj->lock);
+      }
+
+      return -1;
+    }
+
+    doUpdateHashTable(pObj, pNewNode);
+  }
+
+  if (pObj->multithreadSafe) {
+    __unlock(&pObj->lock);
+  }
+
+  return 0;
+}
+
+char *taosGetDataFromHash(HashObj *pObj, const char *key, uint32_t keyLen) {
+  if (pObj->multithreadSafe) {
+    __rd_lock(&pObj->lock);
+  }
+
+  uint32_t   hashVal = 0;
+  SHashNode *pNode = doGetNodeFromHashTable(pObj, key, keyLen, &hashVal);
+
+  if (pObj->multithreadSafe) {
+    __unlock(&pObj->lock);
+  }
+
+  if (pNode != NULL) {
+    assert(pNode->hashVal == hashVal);
+
+    return pNode->data;
+  } else {
+    return NULL;
+  }
+}
+
+/**
+ * remove node in hash list
+ * @param pObj
+ * @param pNode
+ */
+void taosDeleteFromHashTable(HashObj *pObj, const char *key, uint32_t keyLen) {
+  if (pObj->multithreadSafe) {
+    __wr_lock(&pObj->lock);
+  }
+
+  SHashNode *pNode = doGetNodeFromHashTable(pObj, key, keyLen, NULL);
+  if (pNode == NULL) {
+    if (pObj->multithreadSafe) {
+      __unlock(&pObj->lock);
+    }
+
+    return;
+  }
+
+  SHashNode *pNext = pNode->next;
+  if (pNode->prev != NULL) {
+    pNode->prev->next = pNext;
+  }
+  
+  if (pNext != NULL) {
+    pNext->prev = pNode->prev;
+  }
+
+  uint32_t    index = HASH_INDEX(pNode->hashVal, pObj->capacity);
+  SHashEntry *pEntry = pObj->hashList[index];
+  pEntry->num--;
+
+  pObj->size--;
+
+  pNode->next = NULL;
+  pNode->prev = NULL;
+
+  pTrace("key:%s %p remove from hash table", pNode->key, pNode);
+  tfree(pNode);
+
+  if (pObj->multithreadSafe) {
+    __unlock(&pObj->lock);
+  }
+}
+
+void taosCleanUpHashTable(void *handle) {
+  HashObj *pObj = (HashObj *)handle;
+  if (pObj == NULL || pObj->capacity <= 0) return;
+
+  SHashNode *pNode, *pNext;
+
+  if (pObj->multithreadSafe) {
+    __wr_lock(&pObj->lock);
+  }
+
+  if (pObj->hashList) {
+    for (int32_t i = 0; i < pObj->capacity; ++i) {
+      SHashEntry *pEntry = pObj->hashList[i];
+      pNode = pEntry->next;
+
+      while (pNode) {
+        pNext = pNode->next;
+        free(pNode);
+        pNode = pNext;
+      }
+    }
+
+    free(pObj->hashList);
+  }
+
+  if (pObj->multithreadSafe) {
+    __unlock(&pObj->lock);
+    __lock_destroy(&pObj->lock);
+  }
+
+  memset(pObj, 0, sizeof(HashObj));
+  free(pObj);
+}
+
+// for profile only
+int32_t taosGetHashMaxOverflowLength(HashObj* pObj) {
+  if (pObj == NULL || pObj->size == 0) {
+    return 0;
+  }
+  
+  int32_t num = 0;
+  
+  for(int32_t i = 0; i < pObj->size; ++i) {
+    SHashEntry *pEntry = pObj->hashList[i];
+    if (num < pEntry->num) {
+      num = pEntry->num;
+    }
+  }
+  
+  return num;
+}
+
+int32_t taosCheckHashTable(HashObj *pObj) {
+  for(int32_t i = 0; i < pObj->capacity; ++i) {
+    SHashEntry *pEntry = pObj->hashList[i];
+    
+    SHashNode* pNode = pEntry->next;
+    if (pNode != NULL) {
+      assert(pEntry == pNode->prev1);
+      int32_t num = 1;
+      
+      SHashNode* pNext = pNode->next;
+      
+      while(pNext) {
+        assert(pNext->prev == pNode);
+        
+        pNode = pNext;
+        pNext = pNext->next;
+        num ++;
+      }
+      
+      assert(num == pEntry->num);
+    }
+  }
+}
diff --git a/src/util/src/thashutil.c b/src/util/src/thashutil.c
index b6b3ea682ef945a838f67ca227c8033624234725..6166929c729e584c8c34a77a3b1ce5df760845f4 100644
--- a/src/util/src/thashutil.c
+++ b/src/util/src/thashutil.c
@@ -8,6 +8,7 @@
  *
  */
 #include "tutil.h"
+#include "hashutil.h"
 
 #define ROTL32(x, r) ((x) << (r) | (x) >> (32 - (r)))
 
@@ -67,7 +68,7 @@ static void MurmurHash3_32_s(const void *key, int len, uint32_t seed, void *out)
   *(uint32_t *)out = h1;
 }
 
-uint32_t MurmurHash3_32(const void *key, int len) {
+uint32_t MurmurHash3_32(const char *key, uint32_t len) {
   const int32_t hashSeed = 0x12345678;
 
   uint32_t val = 0;
@@ -75,3 +76,26 @@ uint32_t MurmurHash3_32(const void *key, int len) {
 
   return val;
 }
+
+uint32_t taosIntHash_32(const char *key, uint32_t UNUSED_PARAM(len)) { return *(uint32_t *)key; }
+
+uint32_t taosIntHash_64(const char *key, uint32_t UNUSED_PARAM(len)) {
+  uint64_t val = *(uint64_t *)key;
+
+  uint64_t hash = val >> 16U;
+  hash += (val & 0xFFFFU);
+  
+  return hash;
+}
+
+_hash_fn_t taosGetDefaultHashFunction(int32_t type) {
+  _hash_fn_t fn = NULL;
+  switch(type) {
+    case TSDB_DATA_TYPE_BIGINT: fn = taosIntHash_64;break;
+    case TSDB_DATA_TYPE_BINARY: fn = MurmurHash3_32;break;
+    case TSDB_DATA_TYPE_INT: fn = taosIntHash_32; break;
+    default: fn = taosIntHash_32;break;
+  }
+  
+  return fn;
+  }
\ No newline at end of file
diff --git a/src/util/src/ttokenizer.c b/src/util/src/ttokenizer.c
index 0fbc4dc93503db57dd1fd98e79516cfbd89a5515..1caec2736e8a92aa41696334cfdc660a18844868 100644
--- a/src/util/src/ttokenizer.c
+++ b/src/util/src/ttokenizer.c
@@ -14,11 +14,13 @@
  */
 
 #include "os.h"
+#include "hashutil.h"
 #include "shash.h"
 #include "tutil.h"
 #include "tsqldef.h"
 #include "tstoken.h"
 #include "ttypes.h"
+#include "hash.h"
 
 // All the keywords of the SQL language are stored in a hash table
 typedef struct SKeyword {
@@ -225,11 +227,9 @@ static SKeyword keywordTable[] = {
     {"STABLE",       TK_STABLE},
     {"FILE",         TK_FILE},
     {"VNODES",       TK_VNODES},
+    {"UNION",        TK_UNION},
 };
 
-/* This is the hash table */
-static pthread_mutex_t mutex = PTHREAD_MUTEX_INITIALIZER;
-
 static const char isIdChar[] = {
     /* x0 x1 x2 x3 x4 x5 x6 x7 x8 x9 xA xB xC xD xE xF */
     0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, /* 0x */
@@ -243,27 +243,22 @@ static const char isIdChar[] = {
 };
 
 static void* KeywordHashTable = NULL;
-int          tSQLKeywordCode(const char* z, int n) {
-  int         i;
-  static char needInit = 1;
-  if (needInit) {
-    // Initialize the keyword hash table
-    pthread_mutex_lock(&mutex);
-
-    // double check
-    if (needInit) {
-      int nk = tListLen(keywordTable);
-
-      KeywordHashTable = taosInitStrHash(nk, POINTER_BYTES, taosHashStringStep1);
-      for (i = 0; i < nk; i++) {
-        keywordTable[i].len = strlen(keywordTable[i].name);
-        void* ptr = &keywordTable[i];
-        taosAddStrHash(KeywordHashTable, (char*)keywordTable[i].name, (void*)&ptr);
-      }
-      needInit = 0;
-    }
-    pthread_mutex_unlock(&mutex);
+
+static void doInitKeywordsTable() {
+  int numOfEntries = tListLen(keywordTable);
+  
+  KeywordHashTable = taosInitHashTable(numOfEntries, MurmurHash3_32, false);
+  for (int32_t i = 0; i < numOfEntries; i++) {
+    keywordTable[i].len = strlen(keywordTable[i].name);
+    void* ptr = &keywordTable[i];
+    taosAddToHashTable(KeywordHashTable, keywordTable[i].name, keywordTable[i].len, (void*)&ptr, POINTER_BYTES);
   }
+}
+
+static pthread_once_t keywordsHashTableInit = PTHREAD_ONCE_INIT;
+
+int tSQLKeywordCode(const char* z, int n) {
+  pthread_once(&keywordsHashTableInit, doInitKeywordsTable);
 
   char key[128] = {0};
   for (int32_t j = 0; j < n; ++j) {
@@ -274,7 +269,7 @@ int          tSQLKeywordCode(const char* z, int n) {
     }
   }
 
-  SKeyword** pKey = (SKeyword**)taosGetStrHashData(KeywordHashTable, key);
+  SKeyword** pKey = (SKeyword**)taosGetDataFromHash(KeywordHashTable, key, n);
   if (pKey != NULL) {
     return (*pKey)->type;
   } else {