diff --git a/src/balance/src/balance.c b/src/balance/src/balance.c
index df78f4fe27..b172867929 100644
--- a/src/balance/src/balance.c
+++ b/src/balance/src/balance.c
@@ -162,7 +162,6 @@ int32_t balanceAllocVnodes(SVgObj *pVgroup) {
              pDnode->openVnodes, pDnode->diskAvailable, pDnode->alternativeRole);
       mnodeDecDnodeRef(pDnode);
     }
-    sdbFreeIter(pIter);
 
     if (mnodeGetOnlineDnodesNum() == 0) {
       return TSDB_CODE_MND_NOT_READY;
@@ -377,15 +376,13 @@ static bool balanceMonitorBalance() {
                  srcScore, pDestDnode->score, destScore);
           balanceAddVnode(pVgroup, pSrcDnode, pDestDnode);
           mnodeDecVgroupRef(pVgroup);
-          sdbFreeIter(pIter);
+          mnodeCancelGetNextVgroup(pIter);
           return true;
         }
       }
 
       mnodeDecVgroupRef(pVgroup);
     }
-
-    sdbFreeIter(pIter);
   }
 
   return false;
@@ -413,8 +410,6 @@ void balanceReset() {
     mnodeDecDnodeRef(pDnode);
   }
 
-  sdbFreeIter(pIter);
-
   tsAccessSquence = 0;
 }
 
@@ -443,12 +438,11 @@ static int32_t balanceMonitorVgroups() {
 
     mnodeDecVgroupRef(pVgroup);
     if (code == TSDB_CODE_SUCCESS) {
+      mnodeCancelGetNextVgroup(pIter);
       break;
     }
   }
 
-  sdbFreeIter(pIter);
-
   return hasUpdatingVgroup;
 }
 
@@ -465,11 +459,12 @@ static bool balanceMonitorDnodeDropping(SDnodeObj *pDnode) {
     hasThisDnode = balanceCheckDnodeInVgroup(pDnode, pVgroup);
     mnodeDecVgroupRef(pVgroup);
 
-    if (hasThisDnode) break;
+    if (hasThisDnode) {
+      mnodeCancelGetNextVgroup(pIter);
+      break;
+    }
   }
 
-  sdbFreeIter(pIter);
-
   if (!hasThisDnode) {
     mInfo("dnode:%d, dropped for all vnodes are moving to other dnodes", pDnode->dnodeId);
     mnodeDropDnode(pDnode, NULL);
@@ -499,20 +494,18 @@ static bool balanceMontiorDropping() {
       pDnode->status = TAOS_DN_STATUS_DROPPING;
       mnodeUpdateDnode(pDnode);
       mnodeDecDnodeRef(pDnode);
-      sdbFreeIter(pIter);
+      mnodeCancelGetNextDnode(pIter);
       return true;
     }
 
     if (pDnode->status == TAOS_DN_STATUS_DROPPING) {
       bool ret = balanceMonitorDnodeDropping(pDnode);
       mnodeDecDnodeRef(pDnode);
-      sdbFreeIter(pIter);
+      mnodeCancelGetNextDnode(pIter);
       return ret;
     }
   }
 
-  sdbFreeIter(pIter);
-
   return false;
 }
 
@@ -556,8 +549,6 @@ static void balanceSetVgroupOffline(SDnodeObj* pDnode) {
     }
     mnodeDecVgroupRef(pVgroup);
   }
-
-  sdbFreeIter(pIter);
 }
 
 static void balanceCheckDnodeAccess() {
@@ -578,8 +569,6 @@ static void balanceCheckDnodeAccess() {
     }
     mnodeDecDnodeRef(pDnode);
   }
-
-  sdbFreeIter(pIter);
 }
 
 static void balanceProcessBalanceTimer(void *handle, void *tmrId) {
@@ -630,6 +619,7 @@ void balanceAsyncNotify() {
 int32_t balanceInit() {
   mnodeAddShowMetaHandle(TSDB_MGMT_TABLE_SCORES, balanceGetScoresMeta);
   mnodeAddShowRetrieveHandle(TSDB_MGMT_TABLE_SCORES, balanceRetrieveScores);
+  mnodeAddShowFreeIterHandle(TSDB_MGMT_TABLE_SCORES, mnodeCancelGetNextDnode);
   
   pthread_mutex_init(&tsBalanceMutex, NULL);
   balanceInitDnodeList();
@@ -667,8 +657,6 @@ int32_t balanceDropDnode(SDnodeObj *pDnode) {
     mnodeDecDnodeRef(pTempDnode);
   }
 
-  sdbFreeIter(pIter);
-
   if (pDnode->openVnodes > totalFreeVnodes) {
     mError("dnode:%d, openVnodes:%d totalFreeVnodes:%d no enough dnodes", pDnode->dnodeId, pDnode->openVnodes, totalFreeVnodes);
     return TSDB_CODE_MND_NO_ENOUGH_DNODES;
@@ -780,8 +768,12 @@ void balanceAccquireDnodeList() {
   SDnodeObj *pDnode = NULL;
   int32_t    dnodeIndex = 0;
 
-  while (1) {  
-    if (dnodeIndex >= dnodesNum) break;
+  while (1) {
+    if (dnodeIndex >= dnodesNum) {
+      mnodeCancelGetNextDnode(pIter);
+      break;
+    }
+
     pIter = mnodeGetNextDnode(pIter, &pDnode);
     if (pDnode == NULL) break;
     if (pDnode->status == TAOS_DN_STATUS_OFFLINE) {
@@ -802,8 +794,6 @@ void balanceAccquireDnodeList() {
     dnodeIndex++;
   }
 
-  sdbFreeIter(pIter);
-
   tsBalanceDnodeListSize = dnodeIndex;
 }
 
diff --git a/src/connector/go b/src/connector/go
index 050667e5b4..8c58c512b6 160000
--- a/src/connector/go
+++ b/src/connector/go
@@ -1 +1 @@
-Subproject commit 050667e5b4d0eafa5387e4283e713559b421203f
+Subproject commit 8c58c512b6acda8bcdfa48fdc7140227b5221766
diff --git a/src/connector/grafanaplugin b/src/connector/grafanaplugin
index ec77d9049a..d598db167e 160000
--- a/src/connector/grafanaplugin
+++ b/src/connector/grafanaplugin
@@ -1 +1 @@
-Subproject commit ec77d9049a719dabfd1a7c1122a209e201861944
+Subproject commit d598db167eb256fe67409b7bb3d0eb7fffc3ff8c
diff --git a/src/mnode/inc/mnodeAcct.h b/src/mnode/inc/mnodeAcct.h
index 744a62f948..595dcca413 100644
--- a/src/mnode/inc/mnodeAcct.h
+++ b/src/mnode/inc/mnodeAcct.h
@@ -27,6 +27,7 @@ void    mnodeCleanupAccts();
 void    mnodeGetStatOfAllAcct(SAcctInfo* pAcctInfo);
 void *  mnodeGetAcct(char *acctName);
 void *  mnodeGetNextAcct(void *pIter, SAcctObj **pAcct);
+void    mnodeCancelGetNextAcct(void *pIter);
 void    mnodeIncAcctRef(SAcctObj *pAcct);
 void    mnodeDecAcctRef(SAcctObj *pAcct);
 void    mnodeAddDbToAcct(SAcctObj *pAcct, SDbObj *pDb);
diff --git a/src/mnode/inc/mnodeDb.h b/src/mnode/inc/mnodeDb.h
index 7cbd08ed92..9354b923d7 100644
--- a/src/mnode/inc/mnodeDb.h
+++ b/src/mnode/inc/mnodeDb.h
@@ -34,6 +34,7 @@ int64_t mnodeGetDbNum();
 SDbObj *mnodeGetDb(char *db);
 SDbObj *mnodeGetDbByTableId(char *db);
 void *  mnodeGetNextDb(void *pIter, SDbObj **pDb);
+void    mnodeCancelGetNextDb(void *pIter);
 void    mnodeIncDbRef(SDbObj *pDb);
 void    mnodeDecDbRef(SDbObj *pDb);
 bool    mnodeCheckIsMonitorDB(char *db, char *monitordb);
diff --git a/src/mnode/inc/mnodeDnode.h b/src/mnode/inc/mnodeDnode.h
index b6ddb7a9bf..8bc29ef9ef 100644
--- a/src/mnode/inc/mnodeDnode.h
+++ b/src/mnode/inc/mnodeDnode.h
@@ -65,6 +65,7 @@ int32_t mnodeGetDnodesNum();
 int32_t mnodeGetOnlinDnodesCpuCoreNum();
 int32_t mnodeGetOnlineDnodesNum();
 void *  mnodeGetNextDnode(void *pIter, SDnodeObj **pDnode);
+void    mnodeCancelGetNextDnode(void *pIter);
 void    mnodeIncDnodeRef(SDnodeObj *pDnode);
 void    mnodeDecDnodeRef(SDnodeObj *pDnode);
 void *  mnodeGetDnode(int32_t dnodeId);
diff --git a/src/mnode/inc/mnodeMnode.h b/src/mnode/inc/mnodeMnode.h
index a28a03ea40..10cbcebe22 100644
--- a/src/mnode/inc/mnodeMnode.h
+++ b/src/mnode/inc/mnodeMnode.h
@@ -38,6 +38,7 @@ void    mnodeDropMnodeLocal(int32_t dnodeId);
 void *  mnodeGetMnode(int32_t mnodeId);
 int32_t mnodeGetMnodesNum();
 void *  mnodeGetNextMnode(void *pIter, struct SMnodeObj **pMnode);
+void    mnodeCancelGetNextMnode(void *pIter);
 void    mnodeIncMnodeRef(struct SMnodeObj *pMnode);
 void    mnodeDecMnodeRef(struct SMnodeObj *pMnode);
 
diff --git a/src/mnode/inc/mnodeSdb.h b/src/mnode/inc/mnodeSdb.h
index 29d8cf1207..81629ede78 100644
--- a/src/mnode/inc/mnodeSdb.h
+++ b/src/mnode/inc/mnodeSdb.h
@@ -92,9 +92,9 @@ int32_t sdbDeleteRow(SSdbRow *pRow);
 int32_t sdbUpdateRow(SSdbRow *pRow);
 int32_t sdbInsertRowToQueue(SSdbRow *pRow);
 
-void    *sdbGetRow(void *pTable, void *key);
-void    *sdbFetchRow(void *pTable, void *pIter, void **ppRow);
-void     sdbFreeIter(void *pIter);
+void *   sdbGetRow(void *pTable, void *key);
+void *   sdbFetchRow(void *pTable, void *pIter, void **ppRow);
+void     sdbFreeIter(void *pTable, void *pIter);
 void     sdbIncRef(void *pTable, void *pRow);
 void     sdbDecRef(void *pTable, void *pRow);
 int64_t  sdbGetNumOfRows(void *pTable);
diff --git a/src/mnode/inc/mnodeShow.h b/src/mnode/inc/mnodeShow.h
index da66e71678..f985fe792d 100644
--- a/src/mnode/inc/mnodeShow.h
+++ b/src/mnode/inc/mnodeShow.h
@@ -26,8 +26,10 @@ void    mnodeCleanUpShow();
 
 typedef int32_t (*SShowMetaFp)(STableMetaMsg *pMeta, SShowObj *pShow, void *pConn);
 typedef int32_t (*SShowRetrieveFp)(SShowObj *pShow, char *data, int32_t rows, void *pConn);
+typedef void    (*SShowFreeIterFp)(void *pIter);
 void mnodeAddShowMetaHandle(uint8_t showType, SShowMetaFp fp);
 void mnodeAddShowRetrieveHandle(uint8_t showType, SShowRetrieveFp fp);
+void mnodeAddShowFreeIterHandle(uint8_t msgType, SShowFreeIterFp fp);
 void mnodeVacuumResult(char *data, int32_t numOfCols, int32_t rows, int32_t capacity, SShowObj *pShow);
 
 #ifdef __cplusplus
diff --git a/src/mnode/inc/mnodeTable.h b/src/mnode/inc/mnodeTable.h
index 7c0077aa60..bf04f26a90 100644
--- a/src/mnode/inc/mnodeTable.h
+++ b/src/mnode/inc/mnodeTable.h
@@ -31,6 +31,8 @@ void    mnodeIncTableRef(void *pTable);
 void    mnodeDecTableRef(void *pTable);
 void *  mnodeGetNextChildTable(void *pIter, SCTableObj **pTable);
 void *  mnodeGetNextSuperTable(void *pIter, SSTableObj **pTable);
+void    mnodeCancelGetNextChildTable(void *pIter);
+void    mnodeCancelGetNextSuperTable(void *pIter);
 void    mnodeDropAllChildTables(SDbObj *pDropDb);
 void    mnodeDropAllSuperTables(SDbObj *pDropDb);
 void    mnodeDropAllChildTablesInVgroups(SVgObj *pVgroup);
diff --git a/src/mnode/inc/mnodeUser.h b/src/mnode/inc/mnodeUser.h
index 073460f9d3..156bc7aaeb 100644
--- a/src/mnode/inc/mnodeUser.h
+++ b/src/mnode/inc/mnodeUser.h
@@ -25,6 +25,7 @@ int32_t   mnodeInitUsers();
 void      mnodeCleanupUsers();
 SUserObj *mnodeGetUser(char *name);
 void *    mnodeGetNextUser(void *pIter, SUserObj **pUser);
+void      mnodeCancelGetNextUser(void *pIter);
 void      mnodeIncUserRef(SUserObj *pUser);
 void      mnodeDecUserRef(SUserObj *pUser);
 SUserObj *mnodeGetUserFromConn(void *pConn);
diff --git a/src/mnode/inc/mnodeVgroup.h b/src/mnode/inc/mnodeVgroup.h
index 0e6d9dfde4..ee9ec7ae93 100644
--- a/src/mnode/inc/mnodeVgroup.h
+++ b/src/mnode/inc/mnodeVgroup.h
@@ -34,6 +34,7 @@ void    mnodeDropAllDnodeVgroups(SDnodeObj *pDropDnode);
 //void  mnodeUpdateAllDbVgroups(SDbObj *pAlterDb);
 
 void *  mnodeGetNextVgroup(void *pIter, SVgObj **pVgroup);
+void    mnodeCancelGetNextVgroup(void *pIter);
 void    mnodeUpdateVgroup(SVgObj *pVgroup);
 void    mnodeUpdateVgroupStatus(SVgObj *pVgroup, SDnodeObj *pDnode, SVnodeLoad *pVload);
 void    mnodeCheckUnCreatedVgroup(SDnodeObj *pDnode, SVnodeLoad *pVloads, int32_t openVnodes);
diff --git a/src/mnode/src/mnodeAcct.c b/src/mnode/src/mnodeAcct.c
index 9fff2f0229..3da889b284 100644
--- a/src/mnode/src/mnodeAcct.c
+++ b/src/mnode/src/mnodeAcct.c
@@ -144,7 +144,6 @@ void mnodeGetStatOfAllAcct(SAcctInfo* pAcctInfo) {
     pAcctInfo->numOfTimeSeries += pAcct->acctInfo.numOfTimeSeries;
     mnodeDecAcctRef(pAcct);
   }
-  sdbFreeIter(pIter);
 
   SVgObj *pVgroup = NULL;
   pIter = NULL;
@@ -158,7 +157,6 @@ void mnodeGetStatOfAllAcct(SAcctInfo* pAcctInfo) {
     pAcctInfo->totalPoints += pVgroup->pointsWritten;
     mnodeDecVgroupRef(pVgroup);
   }
-  sdbFreeIter(pIter);
 }
 
 void *mnodeGetAcct(char *name) {
@@ -169,6 +167,10 @@ void *mnodeGetNextAcct(void *pIter, SAcctObj **pAcct) {
   return sdbFetchRow(tsAcctSdb, pIter, (void **)pAcct); 
 }
 
+void mnodeCancelGetNextAcct(void *pIter) {
+  sdbFreeIter(tsAcctSdb, pIter);
+}
+
 void mnodeIncAcctRef(SAcctObj *pAcct) {
   sdbIncRef(tsAcctSdb, pAcct);
 }
diff --git a/src/mnode/src/mnodeCluster.c b/src/mnode/src/mnodeCluster.c
index 5be67e4ad9..839407c5b0 100644
--- a/src/mnode/src/mnodeCluster.c
+++ b/src/mnode/src/mnodeCluster.c
@@ -31,6 +31,7 @@ static int32_t mnodeCreateCluster();
 
 static int32_t mnodeGetClusterMeta(STableMetaMsg *pMeta, SShowObj *pShow, void *pConn);
 static int32_t mnodeRetrieveClusters(SShowObj *pShow, char *data, int32_t rows, void *pConn);
+static void    mnodeCancelGetNextCluster(void *pIter);
 
 static int32_t mnodeClusterActionDestroy(SSdbRow *pRow) {
   tfree(pRow->pObj);
@@ -108,6 +109,7 @@ int32_t mnodeInitCluster() {
 
   mnodeAddShowMetaHandle(TSDB_MGMT_TABLE_CLUSTER, mnodeGetClusterMeta);
   mnodeAddShowRetrieveHandle(TSDB_MGMT_TABLE_CLUSTER, mnodeRetrieveClusters);
+  mnodeAddShowFreeIterHandle(TSDB_MGMT_TABLE_CLUSTER, mnodeCancelGetNextCluster);
 
   mDebug("table:%s, hash is created", desc.name);
   return TSDB_CODE_SUCCESS;
@@ -122,6 +124,10 @@ void *mnodeGetNextCluster(void *pIter, SClusterObj **pCluster) {
   return sdbFetchRow(tsClusterSdb, pIter, (void **)pCluster); 
 }
 
+void mnodeCancelGetNextCluster(void *pIter) {
+  sdbFreeIter(tsClusterSdb, pIter);
+}
+
 void mnodeIncClusterRef(SClusterObj *pCluster) {
   sdbIncRef(tsClusterSdb, pCluster);
 }
@@ -167,7 +173,7 @@ void mnodeUpdateClusterId() {
   }
 
   mnodeDecClusterRef(pCluster);
-  sdbFreeIter(pIter);
+  mnodeCancelGetNextCluster(pIter);
 }
 
 static int32_t mnodeGetClusterMeta(STableMetaMsg *pMeta, SShowObj *pShow, void *pConn) {
diff --git a/src/mnode/src/mnodeDb.c b/src/mnode/src/mnodeDb.c
index d121208447..77f3b93eb1 100644
--- a/src/mnode/src/mnodeDb.c
+++ b/src/mnode/src/mnodeDb.c
@@ -171,6 +171,7 @@ int32_t mnodeInitDbs() {
   mnodeAddWriteMsgHandle(TSDB_MSG_TYPE_CM_DROP_DB, mnodeProcessDropDbMsg);
   mnodeAddShowMetaHandle(TSDB_MGMT_TABLE_DB, mnodeGetDbMeta);
   mnodeAddShowRetrieveHandle(TSDB_MGMT_TABLE_DB, mnodeRetrieveDbs);
+  mnodeAddShowFreeIterHandle(TSDB_MGMT_TABLE_DB, mnodeCancelGetNextDb);
   
   mDebug("table:dbs table is created");
   return 0;
@@ -180,6 +181,10 @@ void *mnodeGetNextDb(void *pIter, SDbObj **pDb) {
   return sdbFetchRow(tsDbSdb, pIter, (void **)pDb);
 }
 
+void mnodeCancelGetNextDb(void *pIter) {
+  sdbFreeIter(tsDbSdb, pIter);
+}
+
 SDbObj *mnodeGetDb(char *db) {
   return (SDbObj *)sdbGetRow(tsDbSdb, db);
 }
@@ -986,8 +991,8 @@ static int32_t mnodeAlterDbCb(SMnodeMsg *pMsg, int32_t code) {
   SDbObj *pDb = pMsg->pDb;
 
   void *pIter = NULL;
-  while (1) {
-    SVgObj *pVgroup = NULL;
+  SVgObj *pVgroup = NULL;
+    while (1) {
     pIter = mnodeGetNextVgroup(pIter, &pVgroup);
     if (pVgroup == NULL) break;
     if (pVgroup->pDb == pDb) {
@@ -995,7 +1000,6 @@ static int32_t mnodeAlterDbCb(SMnodeMsg *pMsg, int32_t code) {
     }
     mnodeDecVgroupRef(pVgroup);
   }
-  sdbFreeIter(pIter);
 
   mDebug("db:%s, all vgroups is altered", pDb->name);
   mLInfo("db:%s, is alterd by %s", pDb->name, mnodeGetUserFromMsg(pMsg));
@@ -1146,7 +1150,5 @@ void  mnodeDropAllDbs(SAcctObj *pAcct)  {
     mnodeDecDbRef(pDb);
   }
 
-  sdbFreeIter(pIter);
-
   mInfo("acct:%s, all dbs:%d is dropped from sdb", pAcct->user, numOfDbs);
 }
diff --git a/src/mnode/src/mnodeDnode.c b/src/mnode/src/mnodeDnode.c
index f76533c760..0e9b56e459 100644
--- a/src/mnode/src/mnodeDnode.c
+++ b/src/mnode/src/mnodeDnode.c
@@ -206,6 +206,7 @@ int32_t mnodeInitDnodes() {
   mnodeAddShowRetrieveHandle(TSDB_MGMT_TABLE_VNODES, mnodeRetrieveVnodes);
   mnodeAddShowMetaHandle(TSDB_MGMT_TABLE_DNODE, mnodeGetDnodeMeta);
   mnodeAddShowRetrieveHandle(TSDB_MGMT_TABLE_DNODE, mnodeRetrieveDnodes);
+  mnodeAddShowFreeIterHandle(TSDB_MGMT_TABLE_DNODE, mnodeCancelGetNextDnode);
  
   mDebug("table:dnodes table is created");
   return 0;
@@ -223,6 +224,10 @@ void *mnodeGetNextDnode(void *pIter, SDnodeObj **pDnode) {
   return sdbFetchRow(tsDnodeSdb, pIter, (void **)pDnode); 
 }
 
+void mnodeCancelGetNextDnode(void *pIter) {
+  sdbFreeIter(tsDnodeSdb, pIter);
+}
+
 int32_t mnodeGetDnodesNum() {
   return sdbGetNumOfRows(tsDnodeSdb);
 }
@@ -241,8 +246,6 @@ int32_t mnodeGetOnlinDnodesCpuCoreNum() {
     mnodeDecDnodeRef(pDnode);
   }
 
-  sdbFreeIter(pIter);
-
   if (cpuCores < 2) cpuCores = 2;
   return cpuCores;
 }
@@ -259,8 +262,6 @@ int32_t mnodeGetOnlineDnodesNum() {
     mnodeDecDnodeRef(pDnode);
   }
 
-  sdbFreeIter(pIter);
-
   return onlineDnodes;
 }
 
@@ -276,13 +277,12 @@ void *mnodeGetDnodeByEp(char *ep) {
     pIter = mnodeGetNextDnode(pIter, &pDnode);
     if (pDnode == NULL) break;
     if (strcmp(ep, pDnode->dnodeEp) == 0) {
-      sdbFreeIter(pIter);
+      mnodeCancelGetNextDnode(pIter);
       return pDnode;
     }
     mnodeDecDnodeRef(pDnode);
   }
 
-  sdbFreeIter(pIter);
 
   return NULL;
 }
@@ -464,7 +464,10 @@ static void mnodeUpdateDnodeEps() {
   while (1) {
     pIter = mnodeGetNextDnode(pIter, &pDnode);
     if (pDnode == NULL) break;
-    if (dnodesNum >= totalDnodes) break;
+    if (dnodesNum >= totalDnodes) {
+      mnodeCancelGetNextDnode(pIter);
+      break;
+    }
 
     SDnodeEp *pEp = &tsDnodeEps->dnodeEps[dnodesNum];
     dnodesNum++;
@@ -474,7 +477,6 @@ static void mnodeUpdateDnodeEps() {
     mnodeDecDnodeRef(pDnode);
   }
 
-  sdbFreeIter(pIter);
   pthread_mutex_unlock(&tsDnodeEpsMutex);
 }
 
@@ -1100,7 +1102,7 @@ static int32_t mnodeGetVnodeMeta(STableMetaMsg *pMeta, SShowObj *pShow, void *pC
     pDnode = mnodeGetDnodeByEp(pShow->payload);
   } else {
     void *pIter = mnodeGetNextDnode(NULL, (SDnodeObj **)&pDnode);
-    sdbFreeIter(pIter);
+    mnodeCancelGetNextDnode(pIter);
   }
 
   if (pDnode != NULL) {
@@ -1148,7 +1150,6 @@ static int32_t mnodeRetrieveVnodes(SShowObj *pShow, char *data, int32_t rows, vo
 
       mnodeDecVgroupRef(pVgroup);
     }
-    sdbFreeIter(pIter);
   } else {
     numOfRows = 0;
   }
@@ -1217,8 +1218,6 @@ int32_t balanceAllocVnodes(SVgObj *pVgroup) {
     mnodeDecDnodeRef(pDnode);
   }
 
-  sdbFreeIter(pIter);
-
   if (pSelDnode == NULL) {
     mError("failed to alloc vnode to vgroup");
     return TSDB_CODE_MND_NO_ENOUGH_DNODES;
diff --git a/src/mnode/src/mnodeMnode.c b/src/mnode/src/mnodeMnode.c
index 205bfda4b9..8e3ad0a248 100644
--- a/src/mnode/src/mnodeMnode.c
+++ b/src/mnode/src/mnodeMnode.c
@@ -123,7 +123,7 @@ static int32_t mnodeMnodeActionRestored() {
       pMnode->role = TAOS_SYNC_ROLE_MASTER;
       mnodeDecMnodeRef(pMnode);
     }
-    sdbFreeIter(pIter);
+    mnodeCancelGetNextMnode(pIter);
   }
 
   mnodeUpdateMnodeEpSet();
@@ -161,6 +161,7 @@ int32_t mnodeInitMnodes() {
 
   mnodeAddShowMetaHandle(TSDB_MGMT_TABLE_MNODE, mnodeGetMnodeMeta);
   mnodeAddShowRetrieveHandle(TSDB_MGMT_TABLE_MNODE, mnodeRetrieveMnodes);
+  mnodeAddShowFreeIterHandle(TSDB_MGMT_TABLE_MNODE, mnodeCancelGetNextMnode);
 
   mDebug("table:mnodes table is created");
   return TSDB_CODE_SUCCESS;
@@ -192,6 +193,10 @@ void *mnodeGetNextMnode(void *pIter, SMnodeObj **pMnode) {
   return sdbFetchRow(tsMnodeSdb, pIter, (void **)pMnode); 
 }
 
+void mnodeCancelGetNextMnode(void *pIter) {
+  sdbFreeIter(tsMnodeSdb, pIter);
+}
+
 void mnodeUpdateMnodeEpSet() {
   mInfo("update mnodes epSet, numOfEps:%d ", mnodeGetMnodesNum());
 
@@ -239,8 +244,6 @@ void mnodeUpdateMnodeEpSet() {
   tsMnodeEpSetForShell.numOfEps = index;
   tsMnodeEpSetForPeer.numOfEps = index;
 
-  sdbFreeIter(pIter);
-
   mnodeMnodeUnLock();
 }
 
diff --git a/src/mnode/src/mnodeProfile.c b/src/mnode/src/mnodeProfile.c
index 12ac64854c..8467adfc17 100644
--- a/src/mnode/src/mnodeProfile.c
+++ b/src/mnode/src/mnodeProfile.c
@@ -42,6 +42,7 @@ static int32_t mnodeGetQueryMeta(STableMetaMsg *pMeta, SShowObj *pShow, void *pC
 static int32_t mnodeRetrieveQueries(SShowObj *pShow, char *data, int32_t rows, void *pConn);
 static int32_t mnodeGetConnsMeta(STableMetaMsg *pMeta, SShowObj *pShow, void *pConn);
 static int32_t mnodeRetrieveConns(SShowObj *pShow, char *data, int32_t rows, void *pConn);
+static void    mnodeCancelGetNextConn(void *pIter);
 static int32_t mnodeGetStreamMeta(STableMetaMsg *pMeta, SShowObj *pShow, void *pConn);
 static int32_t mnodeRetrieveStreams(SShowObj *pShow, char *data, int32_t rows, void *pConn);
 static void    mnodeFreeConn(void *data);
@@ -52,10 +53,13 @@ static int32_t mnodeProcessKillConnectionMsg(SMnodeMsg *pMsg);
 int32_t mnodeInitProfile() {
   mnodeAddShowMetaHandle(TSDB_MGMT_TABLE_QUERIES, mnodeGetQueryMeta);
   mnodeAddShowRetrieveHandle(TSDB_MGMT_TABLE_QUERIES, mnodeRetrieveQueries);
+  mnodeAddShowFreeIterHandle(TSDB_MGMT_TABLE_QUERIES, mnodeCancelGetNextConn);
   mnodeAddShowMetaHandle(TSDB_MGMT_TABLE_CONNS, mnodeGetConnsMeta);
   mnodeAddShowRetrieveHandle(TSDB_MGMT_TABLE_CONNS, mnodeRetrieveConns);
+  mnodeAddShowFreeIterHandle(TSDB_MGMT_TABLE_CONNS, mnodeCancelGetNextConn);
   mnodeAddShowMetaHandle(TSDB_MGMT_TABLE_STREAMS, mnodeGetStreamMeta);
   mnodeAddShowRetrieveHandle(TSDB_MGMT_TABLE_STREAMS, mnodeRetrieveStreams);
+  mnodeAddShowFreeIterHandle(TSDB_MGMT_TABLE_STREAMS, mnodeCancelGetNextConn);
 
   mnodeAddWriteMsgHandle(TSDB_MSG_TYPE_CM_KILL_QUERY, mnodeProcessKillQueryMsg);
   mnodeAddWriteMsgHandle(TSDB_MSG_TYPE_CM_KILL_STREAM, mnodeProcessKillStreamMsg);
@@ -137,21 +141,15 @@ static void mnodeFreeConn(void *data) {
   mDebug("connId:%d, is destroyed", pConn->connId);
 }
 
-static void *mnodeGetNextConn(SHashMutableIterator *pIter, SConnObj **pConn) {
+static void *mnodeGetNextConn(void *pIter, SConnObj **pConn) {
   *pConn = NULL;
 
-  if (pIter == NULL) {
-    pIter = taosHashCreateIter(tsMnodeConnCache->pHashTable);
-  }
+  pIter = taosHashIterate(tsMnodeConnCache->pHashTable, pIter);
+  if (pIter == NULL) return NULL;
 
-  if (!taosHashIterNext(pIter)) {
-    taosHashDestroyIter(pIter);
-    return NULL;
-  }
-
-  SCacheDataNode **pNode = taosHashIterGet(pIter);
+  SCacheDataNode **pNode = pIter;
   if (pNode == NULL || *pNode == NULL) {
-    taosHashDestroyIter(pIter);
+    taosHashCancelIterate(tsMnodeConnCache->pHashTable, pIter);
     return NULL;
   }
 
@@ -159,6 +157,10 @@ static void *mnodeGetNextConn(SHashMutableIterator *pIter, SConnObj **pConn) {
   return pIter;
 }
 
+static void mnodeCancelGetNextConn(void *pIter) {
+  taosHashCancelIterate(tsMnodeConnCache->pHashTable, pIter);
+}
+
 static int32_t mnodeGetConnsMeta(STableMetaMsg *pMeta, SShowObj *pShow, void *pConn) {
   SUserObj *pUser = mnodeGetUserFromConn(pConn);
   if (pUser == NULL) return 0;
diff --git a/src/mnode/src/mnodeSdb.c b/src/mnode/src/mnodeSdb.c
index e5fda26687..44e367244c 100644
--- a/src/mnode/src/mnodeSdb.c
+++ b/src/mnode/src/mnodeSdb.c
@@ -325,7 +325,6 @@ void sdbUpdateSync(void *pMnodes) {
       mnodeDecDnodeRef(pDnode);
       mnodeDecMnodeRef(pMnode);
     }
-    sdbFreeIter(pIter);
     syncCfg.replica = index;
     mDebug("vgId:1, mnodes info not input, use infos in sdb, numOfMnodes:%d", syncCfg.replica);
   } else {
@@ -775,24 +774,17 @@ int32_t sdbUpdateRow(SSdbRow *pRow) {
   }
 }
 
-void *sdbFetchRow(void *tparam, void *pNode, void **ppRow) {
+void *sdbFetchRow(void *tparam, void *pIter, void **ppRow) {
   SSdbTable *pTable = tparam;
   *ppRow = NULL;
   if (pTable == NULL) return NULL;
 
-  SHashMutableIterator *pIter = pNode;
-  if (pIter == NULL) {
-    pIter = taosHashCreateIter(pTable->iHandle);
-  }
+  pIter = taosHashIterate(pTable->iHandle, pIter);
+  if (pIter == NULL) return NULL;
 
-  if (!taosHashIterNext(pIter)) {
-    taosHashDestroyIter(pIter);
-    return NULL;
-  }
-
-  void **ppMetaRow = taosHashIterGet(pIter);
+  void **ppMetaRow = pIter;
   if (ppMetaRow == NULL) {
-    taosHashDestroyIter(pIter);
+    taosHashCancelIterate(pTable->iHandle, pIter);
     return NULL;
   }
 
@@ -802,10 +794,11 @@ void *sdbFetchRow(void *tparam, void *pNode, void **ppRow) {
   return pIter;
 }
 
-void sdbFreeIter(void *pIter) {
-  if (pIter != NULL) {
-    taosHashDestroyIter(pIter);
-  }
+void sdbFreeIter(void *tparam, void *pIter) {
+  SSdbTable *pTable = tparam;
+  if (pTable == NULL || pIter == NULL) return;
+
+  taosHashCancelIterate(pTable->iHandle, pIter);
 }
 
 void *sdbOpenTable(SSdbTableDesc *pDesc) {
@@ -846,9 +839,10 @@ void sdbCloseTable(void *handle) {
   tsSdbMgmt.numOfTables--;
   tsSdbMgmt.tableList[pTable->id] = NULL;
 
-  SHashMutableIterator *pIter = taosHashCreateIter(pTable->iHandle);
-  while (taosHashIterNext(pIter)) {
-    void **ppRow = taosHashIterGet(pIter);
+  void *pIter = taosHashIterate(pTable->iHandle, NULL);
+  while (pIter) {
+    void **ppRow = pIter;
+    pIter = taosHashIterate(pTable->iHandle, pIter);
     if (ppRow == NULL) continue;
 
     SSdbRow row = {
@@ -859,7 +853,7 @@ void sdbCloseTable(void *handle) {
     (*pTable->fpDestroy)(&row);
   }
 
-  taosHashDestroyIter(pIter);
+  taosHashCancelIterate(pTable->iHandle, pIter);
   taosHashCleanup(pTable->iHandle);
   pthread_mutex_destroy(&pTable->mutex);
 
diff --git a/src/mnode/src/mnodeShow.c b/src/mnode/src/mnodeShow.c
index 0d53fa9617..2621441cb5 100644
--- a/src/mnode/src/mnodeShow.c
+++ b/src/mnode/src/mnodeShow.c
@@ -57,6 +57,7 @@ static void *tsMnodeShowCache = NULL;
 static int32_t tsShowObjIndex = 0;
 static SShowMetaFp     tsMnodeShowMetaFp[TSDB_MGMT_TABLE_MAX]     = {0};
 static SShowRetrieveFp tsMnodeShowRetrieveFp[TSDB_MGMT_TABLE_MAX] = {0};
+static SShowFreeIterFp tsMnodeShowFreeIterFp[TSDB_MGMT_TABLE_MAX] = {0};
 
 int32_t mnodeInitShow() {
   mnodeAddReadMsgHandle(TSDB_MSG_TYPE_CM_SHOW, mnodeProcessShowMsg);
@@ -85,6 +86,10 @@ void mnodeAddShowRetrieveHandle(uint8_t msgType, SShowRetrieveFp fp) {
   tsMnodeShowRetrieveFp[msgType] = fp;
 }
 
+void mnodeAddShowFreeIterHandle(uint8_t msgType, SShowFreeIterFp fp) {
+  tsMnodeShowFreeIterFp[msgType] = fp;
+}
+
 static char *mnodeGetShowType(int32_t showType) {
   switch (showType) {
     case TSDB_MGMT_TABLE_ACCT:    return "show accounts";
@@ -412,7 +417,9 @@ static void* mnodePutShowObj(SShowObj *pShow) {
 
 static void mnodeFreeShowObj(void *data) {
   SShowObj *pShow = *(SShowObj **)data;
-  sdbFreeIter(pShow->pIter);
+  if (tsMnodeShowFreeIterFp[pShow->type] != NULL && pShow->pIter != NULL) {
+    (*tsMnodeShowFreeIterFp[pShow->type])(pShow->pIter);
+  }
 
   mDebug("%p, show is destroyed, data:%p index:%d", pShow, data, pShow->index);
   tfree(pShow);
diff --git a/src/mnode/src/mnodeTable.c b/src/mnode/src/mnodeTable.c
index d0a5402986..cc7ffb81ad 100644
--- a/src/mnode/src/mnodeTable.c
+++ b/src/mnode/src/mnodeTable.c
@@ -342,8 +342,7 @@ static int32_t mnodeChildTableActionRestored() {
     mnodeDecTableRef(pTable);
   }
 
-  sdbFreeIter(pIter);
-
+  mnodeCancelGetNextChildTable(pIter);
   return 0;
 }
 
@@ -602,10 +601,13 @@ int32_t mnodeInitTables() {
 
   mnodeAddShowMetaHandle(TSDB_MGMT_TABLE_TABLE, mnodeGetShowTableMeta);
   mnodeAddShowRetrieveHandle(TSDB_MGMT_TABLE_TABLE, mnodeRetrieveShowTables);
+  mnodeAddShowFreeIterHandle(TSDB_MGMT_TABLE_TABLE, mnodeCancelGetNextChildTable);
   mnodeAddShowMetaHandle(TSDB_MGMT_TABLE_METRIC, mnodeGetShowSuperTableMeta);
   mnodeAddShowRetrieveHandle(TSDB_MGMT_TABLE_METRIC, mnodeRetrieveShowSuperTables);
+  mnodeAddShowFreeIterHandle(TSDB_MGMT_TABLE_METRIC, mnodeCancelGetNextSuperTable);
   mnodeAddShowMetaHandle(TSDB_MGMT_TABLE_STREAMTABLES, mnodeGetStreamTableMeta);
   mnodeAddShowRetrieveHandle(TSDB_MGMT_TABLE_STREAMTABLES, mnodeRetrieveStreamTables);
+  mnodeAddShowFreeIterHandle(TSDB_MGMT_TABLE_STREAMTABLES, mnodeCancelGetNextChildTable);
 
   return TSDB_CODE_SUCCESS;
 }
@@ -626,14 +628,12 @@ static void *mnodeGetSuperTableByUid(uint64_t uid) {
     pIter = mnodeGetNextSuperTable(pIter, &pStable);
     if (pStable == NULL) break;
     if (pStable->uid == uid) {
-      sdbFreeIter(pIter);
+      mnodeCancelGetNextSuperTable(pIter);
       return pStable;
     }
     mnodeDecTableRef(pStable);
   }
 
-  sdbFreeIter(pIter);
-
   return NULL;
 }
 
@@ -655,10 +655,18 @@ void *mnodeGetNextChildTable(void *pIter, SCTableObj **pTable) {
   return sdbFetchRow(tsChildTableSdb, pIter, (void **)pTable);
 }
 
+void mnodeCancelGetNextChildTable(void *pIter) {
+  sdbFreeIter(tsChildTableSdb, pIter);
+}
+
 void *mnodeGetNextSuperTable(void *pIter, SSTableObj **pTable) {
   return sdbFetchRow(tsSuperTableSdb, pIter, (void **)pTable);
 }
 
+void mnodeCancelGetNextSuperTable(void *pIter) {
+  sdbFreeIter(tsSuperTableSdb, pIter);
+}
+
 void mnodeIncTableRef(void *p1) {
   STableObj *pTable = (STableObj *)p1;
   if (pTable->type == TSDB_SUPER_TABLE) {
@@ -914,10 +922,10 @@ static int32_t mnodeProcessDropSuperTableMsg(SMnodeMsg *pMsg) {
 
   SSTableObj *pStable = (SSTableObj *)pMsg->pTable;
    if (pStable->vgHash != NULL /*pStable->numOfTables != 0*/) {
-    SHashMutableIterator *pIter = taosHashCreateIter(pStable->vgHash);
-    while (taosHashIterNext(pIter)) {
-      int32_t *pVgId = taosHashIterGet(pIter);
+    int32_t *pVgId = taosHashIterate(pStable->vgHash, NULL);
+    while (pVgId) {
       SVgObj *pVgroup = mnodeGetVgroup(*pVgId);
+      pVgId = taosHashIterate(pStable->vgHash, pVgId);
       if (pVgroup == NULL) break;
 
       SDropSTableMsg *pDrop = rpcMallocCont(sizeof(SDropSTableMsg));
@@ -933,7 +941,8 @@ static int32_t mnodeProcessDropSuperTableMsg(SMnodeMsg *pMsg) {
       dnodeSendMsgToDnode(&epSet, &rpcMsg);
       mnodeDecVgroupRef(pVgroup);
     }
-    taosHashDestroyIter(pIter);
+
+    taosHashCancelIterate(pStable->vgHash, pVgId);
 
     mnodeDropAllChildTablesInStable(pStable);
   } 
@@ -1430,8 +1439,6 @@ void mnodeDropAllSuperTables(SDbObj *pDropDb) {
     mnodeDecTableRef(pTable);
   }
 
-  sdbFreeIter(pIter);
-
   mInfo("db:%s, all super tables:%d is dropped from sdb", pDropDb->name, numOfTables);
 }
 
@@ -1523,11 +1530,11 @@ static int32_t mnodeProcessSuperTableVgroupMsg(SMnodeMsg *pMsg) {
     } else {
       SVgroupsMsg *pVgroupMsg = (SVgroupsMsg *)msg;
 
-      SHashMutableIterator *pIter = taosHashCreateIter(pTable->vgHash);
-      int32_t               vgSize = 0;
-      while (taosHashIterNext(pIter)) {
-        int32_t *pVgId = taosHashIterGet(pIter);
-        SVgObj * pVgroup = mnodeGetVgroup(*pVgId);
+      int32_t *pVgId = taosHashIterate(pTable->vgHash, NULL);
+      int32_t  vgSize = 0;
+      while (pVgId) {
+        SVgObj *pVgroup = mnodeGetVgroup(*pVgId);
+        pVgId = taosHashIterate(pTable->vgHash, pVgId);
         if (pVgroup == NULL) continue;
 
         pVgroupMsg->vgroups[vgSize].vgId = htonl(pVgroup->vgId);
@@ -1547,7 +1554,7 @@ static int32_t mnodeProcessSuperTableVgroupMsg(SMnodeMsg *pMsg) {
         mnodeDecVgroupRef(pVgroup);
       }
 
-      taosHashDestroyIter(pIter);
+      taosHashCancelIterate(pTable->vgHash, pVgId);
       mnodeDecTableRef(pTable);
 
       pVgroupMsg->numOfVgroups = htonl(vgSize);
@@ -2230,8 +2237,6 @@ void mnodeDropAllChildTablesInVgroups(SVgObj *pVgroup) {
     mnodeDecTableRef(pTable);
   }
 
-  sdbFreeIter(pIter);
-
   mInfo("vgId:%d, all child tables is dropped from sdb", pVgroup->vgId);
 }
 
@@ -2263,8 +2268,6 @@ void mnodeDropAllChildTables(SDbObj *pDropDb) {
     mnodeDecTableRef(pTable);
   }
 
-  sdbFreeIter(pIter);
-
   mInfo("db:%s, all child tables:%d is dropped from sdb", pDropDb->name, numOfTables);
 }
 
@@ -2293,8 +2296,6 @@ static void mnodeDropAllChildTablesInStable(SSTableObj *pStable) {
     mnodeDecTableRef(pTable);
   }
 
-  sdbFreeIter(pIter);
-
   mInfo("stable:%s, all child tables:%d is dropped from sdb", pStable->info.tableId, numOfTables);
 }
 
diff --git a/src/mnode/src/mnodeUser.c b/src/mnode/src/mnodeUser.c
index dc76d92eb8..aee167631f 100644
--- a/src/mnode/src/mnodeUser.c
+++ b/src/mnode/src/mnodeUser.c
@@ -123,7 +123,6 @@ static void mnodePrintUserAuth() {
   }
 
   fflush(fp);
-  sdbFreeIter(pIter);
   fclose(fp);
 }
 
@@ -177,6 +176,8 @@ int32_t mnodeInitUsers() {
   mnodeAddWriteMsgHandle(TSDB_MSG_TYPE_CM_DROP_USER, mnodeProcessDropUserMsg);
   mnodeAddShowMetaHandle(TSDB_MGMT_TABLE_USER, mnodeGetUserMeta);
   mnodeAddShowRetrieveHandle(TSDB_MGMT_TABLE_USER, mnodeRetrieveUsers);
+  mnodeAddShowFreeIterHandle(TSDB_MGMT_TABLE_USER, mnodeCancelGetNextUser);
+
   mnodeAddPeerMsgHandle(TSDB_MSG_TYPE_DM_AUTH, mnodeProcessAuthMsg);
    
   mDebug("table:%s, hash is created", desc.name);
@@ -196,6 +197,10 @@ void *mnodeGetNextUser(void *pIter, SUserObj **pUser) {
   return sdbFetchRow(tsUserSdb, pIter, (void **)pUser); 
 }
 
+void mnodeCancelGetNextUser(void *pIter) {
+ sdbFreeIter(tsUserSdb, pIter);
+}
+
 void mnodeIncUserRef(SUserObj *pUser) { 
   return sdbIncRef(tsUserSdb, pUser); 
 }
@@ -574,8 +579,6 @@ void mnodeDropAllUsers(SAcctObj *pAcct)  {
     mnodeDecUserRef(pUser);
   }
 
-  sdbFreeIter(pIter);
-
   mDebug("acct:%s, all users:%d is dropped from sdb", pAcct->user, numOfUsers);
 }
 
diff --git a/src/mnode/src/mnodeVgroup.c b/src/mnode/src/mnodeVgroup.c
index f9a49e5ec2..a8343083aa 100644
--- a/src/mnode/src/mnodeVgroup.c
+++ b/src/mnode/src/mnodeVgroup.c
@@ -230,6 +230,7 @@ int32_t mnodeInitVgroups() {
 
   mnodeAddShowMetaHandle(TSDB_MGMT_TABLE_VGROUP, mnodeGetVgroupMeta);
   mnodeAddShowRetrieveHandle(TSDB_MGMT_TABLE_VGROUP, mnodeRetrieveVgroups);
+  mnodeAddShowFreeIterHandle(TSDB_MGMT_TABLE_VGROUP, mnodeCancelGetNextVgroup);
   mnodeAddPeerRspHandle(TSDB_MSG_TYPE_MD_CREATE_VNODE_RSP, mnodeProcessCreateVnodeRsp);
   mnodeAddPeerRspHandle(TSDB_MSG_TYPE_MD_ALTER_VNODE_RSP, mnodeProcessAlterVnodeRsp);
   mnodeAddPeerRspHandle(TSDB_MSG_TYPE_MD_DROP_VNODE_RSP, mnodeProcessDropVnodeRsp);
@@ -304,7 +305,7 @@ void mnodeCheckUnCreatedVgroup(SDnodeObj *pDnode, SVnodeLoad *pVloads, int32_t o
     mnodeDecVgroupRef(pVgroup);
   }
 
-  sdbFreeIter(pIter);
+  mnodeCancelGetNextVgroup(pIter);
 }
 
 void mnodeUpdateVgroupStatus(SVgObj *pVgroup, SDnodeObj *pDnode, SVnodeLoad *pVload) {
@@ -491,6 +492,10 @@ void *mnodeGetNextVgroup(void *pIter, SVgObj **pVgroup) {
   return sdbFetchRow(tsVgroupSdb, pIter, (void **)pVgroup); 
 }
 
+void mnodeCancelGetNextVgroup(void *pIter) {
+  sdbFreeIter(tsVgroupSdb, pIter);
+}
+
 static int32_t mnodeCreateVgroupFp(SMnodeMsg *pMsg) {
   SVgObj *pVgroup = pMsg->pVgroup;
   SDbObj *pDb = pMsg->pDb;
@@ -1095,8 +1100,6 @@ void mnodeDropAllDnodeVgroups(SDnodeObj *pDropDnode) {
     mnodeDecVgroupRef(pVgroup);
   }
 
-  sdbFreeIter(pIter);
-
   mInfo("dnode:%d, all vgroups:%d is dropped from sdb", pDropDnode->dnodeId, numOfVgroups);
 }
 
@@ -1118,8 +1121,6 @@ void mnodeUpdateAllDbVgroups(SDbObj *pAlterDb) {
     mnodeDecVgroupRef(pVgroup);
   }
 
-  sdbFreeIter(pIter);
-
   mInfo("db:%s, all vgroups is updated in sdb", pAlterDb->name);
 }
 #endif
@@ -1147,8 +1148,6 @@ void mnodeDropAllDbVgroups(SDbObj *pDropDb) {
     mnodeDecVgroupRef(pVgroup);
   }
 
-  sdbFreeIter(pIter);
-
   mInfo("db:%s, all vgroups:%d is dropped from sdb", pDropDb->name, numOfVgroups);
 }
 
@@ -1170,7 +1169,5 @@ void mnodeSendDropAllDbVgroupsMsg(SDbObj *pDropDb) {
     numOfVgroups++;
   }
 
-  sdbFreeIter(pIter);
-
   mInfo("db:%s, all vgroups:%d drop msg is sent to dnode", pDropDb->name, numOfVgroups);
 }
diff --git a/src/query/src/qResultbuf.c b/src/query/src/qResultbuf.c
index 55a7aea53a..bc7243830d 100644
--- a/src/query/src/qResultbuf.c
+++ b/src/query/src/qResultbuf.c
@@ -423,9 +423,8 @@ void destroyResultBuf(SDiskbasedResultBuf* pResultBuf) {
   unlink(pResultBuf->path);
   tfree(pResultBuf->path);
 
-  SHashMutableIterator* iter = taosHashCreateIter(pResultBuf->groupSet);
-  while(taosHashIterNext(iter)) {
-    SArray** p = (SArray**) taosHashIterGet(iter);
+  SArray** p = taosHashIterate(pResultBuf->groupSet, NULL);
+  while(p) {
     size_t n = taosArrayGetSize(*p);
     for(int32_t i = 0; i < n; ++i) {
       SPageInfo* pi = taosArrayGetP(*p, i);
@@ -434,10 +433,9 @@ void destroyResultBuf(SDiskbasedResultBuf* pResultBuf) {
     }
 
     taosArrayDestroy(*p);
+    p = taosHashIterate(pResultBuf->groupSet, p);
   }
 
-  taosHashDestroyIter(iter);
-
   tdListFree(pResultBuf->lruList);
   taosArrayDestroy(pResultBuf->emptyDummyIdList);
   taosHashCleanup(pResultBuf->groupSet);
diff --git a/src/rpc/src/rpcTcp.c b/src/rpc/src/rpcTcp.c
index 7b8cf3cda2..2850046d05 100644
--- a/src/rpc/src/rpcTcp.c
+++ b/src/rpc/src/rpcTcp.c
@@ -371,10 +371,13 @@ void taosCloseTcpConnection(void *chandle) {
 
 int taosSendTcpData(uint32_t ip, uint16_t port, void *data, int len, void *chandle) {
   SFdObj *pFdObj = chandle;
-
   if (pFdObj == NULL || pFdObj->signature != pFdObj) return -1;
+  SThreadObj *pThreadObj = pFdObj->pThreadObj;
 
-  return taosWriteMsg(pFdObj->fd, data, len);
+  int ret = taosWriteMsg(pFdObj->fd, data, len);
+  tTrace("%s %p TCP data is sent, FD:%p fd:%d bytes:%d", pThreadObj->label, pFdObj->thandle, pFdObj, pFdObj->fd, ret); 
+
+  return ret;
 }
 
 static void taosReportBrokenLink(SFdObj *pFdObj) {
@@ -409,7 +412,7 @@ static int taosReadTcpData(SFdObj *pFdObj, SRecvInfo *pInfo) {
 
   headLen = taosReadMsg(pFdObj->fd, &rpcHead, sizeof(SRpcHead));
   if (headLen != sizeof(SRpcHead)) {
-    tDebug("%s %p read error, headLen:%d", pThreadObj->label, pFdObj->thandle, headLen);
+    tDebug("%s %p read error, FD:%p headLen:%d", pThreadObj->label, pFdObj->thandle, pFdObj, headLen);
     return -1; 
   }
 
@@ -420,7 +423,7 @@ static int taosReadTcpData(SFdObj *pFdObj, SRecvInfo *pInfo) {
     tError("%s %p TCP malloc(size:%d) fail", pThreadObj->label, pFdObj->thandle, msgLen);
     return -1;
   } else {
-    tTrace("TCP malloc mem:%p size:%d", buffer, size);
+    tTrace("%s %p read data, FD:%p fd:%d TCP malloc mem:%p", pThreadObj->label, pFdObj->thandle, pFdObj, pFdObj->fd, buffer);
   }
 
   msg = buffer + tsRpcOverhead;
@@ -583,8 +586,8 @@ static void taosFreeFdObj(SFdObj *pFdObj) {
 
   pthread_mutex_unlock(&pThreadObj->mutex);
 
-  tDebug("%s %p TCP connection is closed, FD:%p numOfFds:%d", 
-          pThreadObj->label, pFdObj->thandle, pFdObj, pThreadObj->numOfFds);
+  tDebug("%s %p TCP connection is closed, FD:%p fd:%d numOfFds:%d", 
+          pThreadObj->label, pFdObj->thandle, pFdObj, pFdObj->fd, pThreadObj->numOfFds);
 
   tfree(pFdObj);
 }
diff --git a/src/util/inc/hash.h b/src/util/inc/hash.h
index 42bc136584..b0319d3e13 100644
--- a/src/util/inc/hash.h
+++ b/src/util/inc/hash.h
@@ -31,16 +31,18 @@ extern "C" {
 typedef void (*_hash_free_fn_t)(void *param);
 
 typedef struct SHashNode {
-//  char             *key;
   struct SHashNode *next;
   uint32_t          hashVal;  // the hash value of key
   uint32_t          keyLen;   // length of the key
-//  char             *data;
+  size_t            dataLen;  // length of data
+  int8_t            count;    // reference count
+  int8_t            removed;  // flag to indicate removed
+  char              data[];
 } SHashNode;
 
-#define GET_HASH_NODE_KEY(_n)  ((char*)(_n) + sizeof(SHashNode))
-#define GET_HASH_NODE_DATA(_n) ((char*)(_n) + sizeof(SHashNode) + (_n)->keyLen)
-
+#define GET_HASH_NODE_KEY(_n)  ((char*)(_n) + sizeof(SHashNode) + (_n)->dataLen)
+#define GET_HASH_NODE_DATA(_n) ((char*)(_n) + sizeof(SHashNode))
+#define GET_HASH_PNODE(_n) ((char*)(_n) - sizeof(SHashNode));
 typedef enum SHashLockTypeE {
   HASH_NO_LOCK     = 0,
   HASH_ENTRY_LOCK  = 1,
@@ -65,15 +67,6 @@ typedef struct SHashObj {
   SArray         *pMemBlock;    // memory block allocated for SHashEntry
 } SHashObj;
 
-typedef struct SHashMutableIterator {
-  SHashObj  *pHashObj;
-  int32_t    entryIndex;
-  SHashNode *pCur;
-  SHashNode *pNext;           // current node can be deleted for mutable iterator, so keep the next one before return current
-  size_t     numOfChecked;    // already check number of elements in hash table
-  size_t     numOfEntries;    // number of entries while the iterator is created
-} SHashMutableIterator;
-
 /**
  * init the hash table
  *
@@ -142,33 +135,9 @@ int32_t taosHashCondTraverse(SHashObj *pHashObj, bool (*fp)(void *, void *), voi
  */
 void taosHashCleanup(SHashObj *pHashObj);
 
-/**
- *
- * @param pHashObj
- * @return
- */
-SHashMutableIterator* taosHashCreateIter(SHashObj *pHashObj);
-
-/**
- *
- * @param iter
- * @return
- */
-bool taosHashIterNext(SHashMutableIterator *iter);
-
-/**
- *
- * @param iter
- * @return
- */
-void *taosHashIterGet(SHashMutableIterator *iter);
-
-/**
- *
- * @param iter
- * @return
- */
-void* taosHashDestroyIter(SHashMutableIterator* iter);
+/*
+void *SHashMutableIterator* taosHashCreateIter(SHashObj *pHashObj, void *);
+*/
 
 /**
  *
@@ -179,6 +148,9 @@ int32_t taosHashGetMaxOverflowLinkLength(const SHashObj *pHashObj);
 
 size_t taosHashGetMemSize(const SHashObj *pHashObj);
 
+void *taosHashIterate(SHashObj *pHashObj, void *p);
+void  taosHashCancelIterate(SHashObj *pHashObj, void *p);
+
 #ifdef __cplusplus
 }
 #endif
diff --git a/src/util/src/hash.c b/src/util/src/hash.c
index 03a7342497..3ac54eedd8 100644
--- a/src/util/src/hash.c
+++ b/src/util/src/hash.c
@@ -76,7 +76,7 @@ static FORCE_INLINE int32_t taosHashCapacity(int32_t length) {
 static FORCE_INLINE SHashNode *doSearchInEntryList(SHashEntry *pe, const void *key, size_t keyLen, uint32_t hashVal) {
   SHashNode *pNode = pe->next;
   while (pNode) {
-    if ((pNode->keyLen == keyLen) && (memcmp(GET_HASH_NODE_KEY(pNode), key, keyLen) == 0)) {
+    if ((pNode->keyLen == keyLen) && (memcmp(GET_HASH_NODE_KEY(pNode), key, keyLen) == 0) && pNode->removed == 0) {
       assert(pNode->hashVal == hashVal);
       break;
     }
@@ -114,15 +114,25 @@ static SHashNode *doCreateHashNode(const void *key, size_t keyLen, const void *p
  * @param dsize   size of actual data
  * @return        hash node
  */
-static FORCE_INLINE SHashNode *doUpdateHashNode(SHashEntry* pe, SHashNode* prev, SHashNode *pNode, SHashNode *pNewNode) {
+static FORCE_INLINE SHashNode *doUpdateHashNode(SHashObj *pHashObj, SHashEntry* pe, SHashNode* prev, SHashNode *pNode, SHashNode *pNewNode) {
   assert(pNode->keyLen == pNewNode->keyLen);
+
+  pNode->count--;
   if (prev != NULL) {
     prev->next = pNewNode;
   } else {
     pe->next = pNewNode;
   }
 
-  pNewNode->next = pNode->next;
+  if (pNode->count <= 0) {
+    pNewNode->next = pNode->next;
+    DO_FREE_HASH_NODE(pNode);
+  } else {
+    pNewNode->next = pNode;    
+    pe->num++;
+    atomic_add_fetch_64(&pHashObj->size, 1);
+  }
+  
   return pNewNode;
 }
 
@@ -139,7 +149,6 @@ static void pushfrontNodeInEntryList(SHashEntry *pEntry, SHashNode *pNode);
  * @param pIter
  * @return
  */
-static SHashNode *getNextHashNode(SHashMutableIterator *pIter);
 
 SHashObj *taosHashInit(size_t capacity, _hash_fn_t fn, bool update, SHashLockTypeE type) {
   if (capacity == 0 || fn == NULL) {
@@ -213,7 +222,7 @@ int32_t taosHashPut(SHashObj *pHashObj, const void *key, size_t keyLen, void *da
 
   SHashNode* prev = NULL;
   while (pNode) {
-    if ((pNode->keyLen == keyLen) && (memcmp(GET_HASH_NODE_KEY(pNode), key, keyLen) == 0)) {
+    if ((pNode->keyLen == keyLen) && (memcmp(GET_HASH_NODE_KEY(pNode), key, keyLen) == 0) && pNode->removed == 0) {
       assert(pNode->hashVal == hashVal);
       break;
     }
@@ -244,8 +253,7 @@ int32_t taosHashPut(SHashObj *pHashObj, const void *key, size_t keyLen, void *da
   } else {
     // not support the update operation, return error
     if (pHashObj->enableUpdate) {
-      doUpdateHashNode(pe, prev, pNode, pNewNode);
-      DO_FREE_HASH_NODE(pNode);
+      doUpdateHashNode(pHashObj, pe, prev, pNode, pNewNode);
     } else {
       DO_FREE_HASH_NODE(pNewNode);
     }
@@ -335,22 +343,10 @@ int32_t taosHashRemoveWithData(SHashObj *pHashObj, const void *key, size_t keyLe
   int32_t     slot = HASH_INDEX(hashVal, pHashObj->capacity);
   SHashEntry *pe = pHashObj->hashList[slot];
 
-  // no data, return directly
-  if (pe->num == 0) {
-    __rd_unlock(&pHashObj->lock, pHashObj->type);
-    return -1;
-  }
-
   if (pHashObj->type == HASH_ENTRY_LOCK) {
     taosWLockLatch(&pe->latch);
   }
 
-  if (pe->num == 0) {
-    assert(pe->next == NULL);
-  } else {
-    assert(pe->next != NULL);
-  }
-
   // double check after locked
   if (pe->num == 0) {
     assert(pe->next == NULL);
@@ -360,37 +356,37 @@ int32_t taosHashRemoveWithData(SHashObj *pHashObj, const void *key, size_t keyLe
     return -1;
   }
 
+  int code = -1;
   SHashNode *pNode = pe->next;
-  SHashNode *pRes = NULL;
+  SHashNode *prevNode = NULL;
 
-  // remove it
-  if ((pNode->keyLen == keyLen) && (memcmp(GET_HASH_NODE_KEY(pNode), key, keyLen) == 0)) {
-    pe->num -= 1;
-    pRes = pNode;
-    pe->next = pNode->next;
-  } else {
-    while (pNode->next != NULL) {
-      if (((pNode->next)->keyLen == keyLen) && (memcmp(GET_HASH_NODE_KEY((pNode->next)), key, keyLen) == 0)) {
-        assert((pNode->next)->hashVal == hashVal);
-        break;
+  while (pNode) {
+    if ((pNode->keyLen == keyLen) && (memcmp(GET_HASH_NODE_KEY(pNode), key, keyLen) == 0) && pNode->removed == 0) 
+      break;
+
+    prevNode = pNode;
+    pNode = pNode->next;
+  }
+
+  if (pNode) {
+    code = 0;  // it is found
+
+    pNode->count--;
+    pNode->removed = 1;
+    if (pNode->count <= 0) {
+      if (prevNode) {
+        prevNode->next = pNode->next;
+      } else {
+        pe->next = pNode->next;
       }
+   
+      if (data) memcpy(data, GET_HASH_NODE_DATA(pNode), dsize);
 
-      pNode = pNode->next;
+      pe->num--;
+      atomic_sub_fetch_64(&pHashObj->size, 1);
+      FREE_HASH_NODE(pHashObj, pNode);
     }
-
-
-    if (pNode->next != NULL) {
-      pe->num -= 1;
-      pRes = pNode->next;
-      pNode->next = pNode->next->next;
-    }
-  }
-
-  if (pe->num == 0) {
-    assert(pe->next == NULL);
-  } else {
-    assert(pe->next != NULL);
-  }
+  } 
 
   if (pHashObj->type == HASH_ENTRY_LOCK) {
     taosWUnLockLatch(&pe->latch);
@@ -398,17 +394,7 @@ int32_t taosHashRemoveWithData(SHashObj *pHashObj, const void *key, size_t keyLe
 
   __rd_unlock(&pHashObj->lock, pHashObj->type);
 
-  if (data != NULL && pRes != NULL) {
-    memcpy(data, GET_HASH_NODE_DATA(pRes), dsize);
-  }
-
-  if (pRes != NULL) {
-    atomic_sub_fetch_64(&pHashObj->size, 1);
-    FREE_HASH_NODE(pHashObj, pRes);
-    return 0;
-  } else {
-    return -1;
-  }
+  return code;
 }
 
 int32_t taosHashCondTraverse(SHashObj *pHashObj, bool (*fp)(void *, void *), void *param) {
@@ -531,98 +517,6 @@ void taosHashCleanup(SHashObj *pHashObj) {
   free(pHashObj);
 }
 
-SHashMutableIterator *taosHashCreateIter(SHashObj *pHashObj) {
-  SHashMutableIterator *pIter = calloc(1, sizeof(SHashMutableIterator));
-  if (pIter == NULL) {
-    return NULL;
-  }
-
-  pIter->pHashObj = pHashObj;
-
-  // keep it in local variable, in case the resize operation expand the size
-  pIter->numOfEntries = pHashObj->capacity;
-  return pIter;
-}
-
-bool taosHashIterNext(SHashMutableIterator *pIter) {
-  if (pIter == NULL) {
-    return false;
-  }
-
-  size_t size = taosHashGetSize(pIter->pHashObj);
-  if (size == 0) {
-    return false;
-  }
-
-  // check the first one
-  if (pIter->numOfChecked == 0) {
-    assert(pIter->pCur == NULL && pIter->pNext == NULL);
-
-    while (1) {
-      SHashEntry *pEntry = pIter->pHashObj->hashList[pIter->entryIndex];
-      if (pEntry->num == 0) {
-        assert(pEntry->next == NULL);
-
-        pIter->entryIndex++;
-        continue;
-      }
-
-      if (pIter->pHashObj->type == HASH_ENTRY_LOCK) {
-        taosRLockLatch(&pEntry->latch);
-      }
-
-      pIter->pCur = pEntry->next;
-
-      if (pIter->pCur->next) {
-        pIter->pNext = pIter->pCur->next;
-
-        if (pIter->pHashObj->type == HASH_ENTRY_LOCK) {
-          taosRUnLockLatch(&pEntry->latch);
-        }
-      } else {
-        if (pIter->pHashObj->type == HASH_ENTRY_LOCK) {
-          taosRUnLockLatch(&pEntry->latch);
-        }
-
-        pIter->pNext = getNextHashNode(pIter);
-      }
-
-      break;
-    }
-
-    pIter->numOfChecked++;
-    return true;
-  } else {
-    assert(pIter->pCur != NULL);
-    if (pIter->pNext) {
-      pIter->pCur = pIter->pNext;
-    } else {  // no more data in the hash list
-      return false;
-    }
-
-    pIter->numOfChecked++;
-
-    if (pIter->pCur->next) {
-      pIter->pNext = pIter->pCur->next;
-    } else {
-      pIter->pNext = getNextHashNode(pIter);
-    }
-
-    return true;
-  }
-}
-
-void *taosHashIterGet(SHashMutableIterator *iter) { return (iter == NULL) ? NULL : GET_HASH_NODE_DATA(iter->pCur); }
-
-void *taosHashDestroyIter(SHashMutableIterator *iter) {
-  if (iter == NULL) {
-    return NULL;
-  }
-
-  free(iter);
-  return NULL;
-}
-
 // for profile only
 int32_t taosHashGetMaxOverflowLinkLength(const SHashObj *pHashObj) {
   if (pHashObj == NULL || pHashObj->size == 0) {
@@ -759,6 +653,8 @@ SHashNode *doCreateHashNode(const void *key, size_t keyLen, const void *pData, s
 
   pNewNode->keyLen = (uint32_t)keyLen;
   pNewNode->hashVal = hashVal;
+  pNewNode->dataLen = dsize;
+  pNewNode->count = 1;
 
   memcpy(GET_HASH_NODE_DATA(pNewNode), pData, dsize);
   memcpy(GET_HASH_NODE_KEY(pNewNode), key, keyLen);
@@ -775,35 +671,6 @@ void pushfrontNodeInEntryList(SHashEntry *pEntry, SHashNode *pNode) {
   pEntry->num += 1;
 }
 
-SHashNode *getNextHashNode(SHashMutableIterator *pIter) {
-  assert(pIter != NULL);
-
-  pIter->entryIndex++;
-  SHashNode *p = NULL;
-
-  while (pIter->entryIndex < pIter->numOfEntries) {
-    SHashEntry *pEntry = pIter->pHashObj->hashList[pIter->entryIndex];
-    if (pEntry->num == 0) {
-      pIter->entryIndex++;
-      continue;
-    }
-
-    if (pIter->pHashObj->type == HASH_ENTRY_LOCK) {
-      taosRLockLatch(&pEntry->latch);
-    }
-
-    p = pEntry->next;
-
-    if (pIter->pHashObj->type == HASH_ENTRY_LOCK) {
-      taosRUnLockLatch(&pEntry->latch);
-    }
-
-    return p;
-  }
-
-  return NULL;
-}
-
 size_t taosHashGetMemSize(const SHashObj *pHashObj) {
   if (pHashObj == NULL) {
     return 0;
@@ -811,3 +678,129 @@ size_t taosHashGetMemSize(const SHashObj *pHashObj) {
 
   return (pHashObj->capacity * (sizeof(SHashEntry) + POINTER_BYTES)) + sizeof(SHashNode) * taosHashGetSize(pHashObj) + sizeof(SHashObj);
 }
+
+// release the pNode, return next pNode, and lock the current entry
+static void *taosHashReleaseNode(SHashObj *pHashObj, void *p, int *slot) {
+
+  SHashNode *pOld = (SHashNode *)GET_HASH_PNODE(p);
+  SHashNode *prevNode = NULL;
+
+  *slot = HASH_INDEX(pOld->hashVal, pHashObj->capacity);
+  SHashEntry *pe = pHashObj->hashList[*slot];
+
+  // lock entry
+  if (pHashObj->type == HASH_ENTRY_LOCK) {
+    taosWLockLatch(&pe->latch);
+  }
+
+  SHashNode *pNode = pe->next;
+
+  while (pNode) {
+    if (pNode == pOld) 
+      break;
+
+    prevNode = pNode;
+    pNode = pNode->next;
+  }
+
+  if (pNode) { 
+    pNode = pNode->next;
+    while (pNode) {
+      if (pNode->removed == 0) break;
+      pNode = pNode->next;
+    }
+
+    pOld->count--;
+    if (pOld->count <=0) {
+      if (prevNode) {
+        prevNode->next = pOld->next;
+      } else {
+        pe->next = pOld->next;
+      }
+   
+      pe->num--;
+      atomic_sub_fetch_64(&pHashObj->size, 1);
+      FREE_HASH_NODE(pHashObj, pOld);
+    } 
+  } else {
+    uError("pNode:%p data:%p is not there!!!", pNode, p);
+  }
+
+  return pNode;
+}
+
+void *taosHashIterate(SHashObj *pHashObj, void *p) {
+  if (pHashObj == NULL) return NULL; 
+
+  int  slot = 0;
+  char *data = NULL;
+
+  // only add the read lock to disable the resize process
+  __rd_lock(&pHashObj->lock, pHashObj->type);
+
+  SHashNode *pNode = NULL;
+  if (p) {
+    pNode = taosHashReleaseNode(pHashObj, p, &slot);
+    if (pNode == NULL) {
+      SHashEntry *pe = pHashObj->hashList[slot];
+      if (pHashObj->type == HASH_ENTRY_LOCK) {
+        taosWUnLockLatch(&pe->latch);
+      } 
+
+      slot = slot + 1;
+    }
+  }
+
+  if (pNode == NULL) {
+    for (; slot < pHashObj->capacity; ++slot) {
+      SHashEntry *pe = pHashObj->hashList[slot];
+
+      // lock entry
+      if (pHashObj->type == HASH_ENTRY_LOCK) {
+        taosWLockLatch(&pe->latch);
+      }
+
+      pNode = pe->next;
+      while (pNode) {
+        if (pNode->removed == 0) break;
+        pNode = pNode->next;
+      }
+
+      if (pNode) break;
+
+      if (pHashObj->type == HASH_ENTRY_LOCK) {
+        taosWUnLockLatch(&pe->latch);
+      } 
+    }
+  }
+
+  if (pNode) {
+    SHashEntry *pe = pHashObj->hashList[slot];
+    pNode->count++;
+    data = GET_HASH_NODE_DATA(pNode);
+    if (pHashObj->type == HASH_ENTRY_LOCK) {
+      taosWUnLockLatch(&pe->latch);
+    } 
+  }
+
+  __rd_unlock(&pHashObj->lock, pHashObj->type);
+  return data;
+
+}
+
+void taosHashCancelIterate(SHashObj *pHashObj, void *p) {
+  if (pHashObj == NULL || p == NULL) return;
+
+  // only add the read lock to disable the resize process
+  __rd_lock(&pHashObj->lock, pHashObj->type);
+
+  int slot;
+  taosHashReleaseNode(pHashObj, p, &slot);
+
+  SHashEntry *pe = pHashObj->hashList[slot];
+  if (pHashObj->type == HASH_ENTRY_LOCK) {
+    taosWUnLockLatch(&pe->latch);
+  } 
+
+  __rd_unlock(&pHashObj->lock, pHashObj->type);
+}
diff --git a/src/util/src/tkvstore.c b/src/util/src/tkvstore.c
index 31641ac9a7..2b1d13c78b 100644
--- a/src/util/src/tkvstore.c
+++ b/src/util/src/tkvstore.c
@@ -529,7 +529,7 @@ static int tdRestoreKVStore(SKVStore *pStore) {
   void *                buf = NULL;
   int64_t               maxBufSize = 0;
   SKVRecord             rInfo = {0};
-  SHashMutableIterator *pIter = NULL;
+  SKVRecord            *pRecord = NULL;
 
   ASSERT(TD_KVSTORE_HEADER_SIZE == lseek(pStore->fd, 0, SEEK_CUR));
   ASSERT(pStore->info.size == TD_KVSTORE_HEADER_SIZE);
@@ -582,16 +582,8 @@ static int tdRestoreKVStore(SKVStore *pStore) {
     goto _err;
   }
 
-  pIter = taosHashCreateIter(pStore->map);
-  if (pIter == NULL) {
-    uError("failed to create hash iter while opening KV store %s", pStore->fname);
-    terrno = TSDB_CODE_COM_OUT_OF_MEMORY;
-    goto _err;
-  }
-
-  while (taosHashIterNext(pIter)) {
-    SKVRecord *pRecord = taosHashIterGet(pIter);
-
+  pRecord = taosHashIterate(pStore->map, NULL);
+  while (pRecord) {
     if (lseek(pStore->fd, (off_t)(pRecord->offset + sizeof(SKVRecord)), SEEK_SET) < 0) {
       uError("failed to lseek file %s since %s, offset %" PRId64, pStore->fname, strerror(errno), pRecord->offset);
       terrno = TAOS_SYSTEM_ERROR(errno);
@@ -613,16 +605,17 @@ static int tdRestoreKVStore(SKVStore *pStore) {
         goto _err;
       }
     }
+
+    pRecord = taosHashIterate(pStore->map, pRecord);
   }
 
   if (pStore->aFunc) (*pStore->aFunc)(pStore->appH);
 
-  taosHashDestroyIter(pIter);
   tfree(buf);
   return 0;
 
 _err:
-  taosHashDestroyIter(pIter);
+  taosHashCancelIterate(pStore->map, pRecord);
   tfree(buf);
   return -1;
 }
diff --git a/src/vnode/src/vnodeMain.c b/src/vnode/src/vnodeMain.c
index cd6d2ea7c0..c10d4a7a8c 100644
--- a/src/vnode/src/vnodeMain.c
+++ b/src/vnode/src/vnodeMain.c
@@ -520,11 +520,10 @@ static void vnodeBuildVloadMsg(SVnodeObj *pVnode, SStatusMsg *pStatus) {
 }
 
 int32_t vnodeGetVnodeList(int32_t vnodeList[], int32_t *numOfVnodes) {
-  SHashMutableIterator *pIter = taosHashCreateIter(tsVnodesHash);
-  while (taosHashIterNext(pIter)) {
-    SVnodeObj **pVnode = taosHashIterGet(pIter);
-    if (pVnode == NULL) continue;
-    if (*pVnode == NULL) continue;
+  void *pIter = taosHashIterate(tsVnodesHash, NULL);
+  while (pIter) {
+    SVnodeObj **pVnode = pIter;
+    if (*pVnode) {
 
     (*numOfVnodes)++;
     if (*numOfVnodes >= TSDB_MAX_VNODES) {
@@ -533,25 +532,25 @@ int32_t vnodeGetVnodeList(int32_t vnodeList[], int32_t *numOfVnodes) {
     } else {
       vnodeList[*numOfVnodes - 1] = (*pVnode)->vgId;
     }
-  }
 
-  taosHashDestroyIter(pIter);
+    }
+
+    pIter = taosHashIterate(tsVnodesHash, pIter);    
+  }
   return TSDB_CODE_SUCCESS;
 }
 
 void vnodeBuildStatusMsg(void *param) {
   SStatusMsg *pStatus = param;
-  SHashMutableIterator *pIter = taosHashCreateIter(tsVnodesHash);
 
-  while (taosHashIterNext(pIter)) {
-    SVnodeObj **pVnode = taosHashIterGet(pIter);
-    if (pVnode == NULL) continue;
-    if (*pVnode == NULL) continue;
-
-    vnodeBuildVloadMsg(*pVnode, pStatus);
+  void *pIter = taosHashIterate(tsVnodesHash, NULL);
+  while (pIter) {
+    SVnodeObj **pVnode = pIter;
+    if (*pVnode) {
+      vnodeBuildVloadMsg(*pVnode, pStatus);
+    }
+    pIter = taosHashIterate(tsVnodesHash, pIter);
   }
-
-  taosHashDestroyIter(pIter);
 }
 
 void vnodeSetAccess(SVgroupAccess *pAccess, int32_t numOfVnodes) {
diff --git a/tests/script/basicSuite.sim b/tests/script/basicSuite.sim
index 61a9d68d26..5e22e02297 100644
--- a/tests/script/basicSuite.sim
+++ b/tests/script/basicSuite.sim
@@ -14,7 +14,6 @@ run general/table/vgroup.sim
 run general/user/authority.sim
 run general/vector/metrics_mix.sim
 run general/vector/table_field.sim
-run general/user/authority.sim
 run general/tag/set.sim
 run general/table/delete_writing.sim
 run general/stable/disk.sim
diff --git a/tests/test/c/CMakeLists.txt b/tests/test/c/CMakeLists.txt
index 26aa20e647..11480a8ba2 100644
--- a/tests/test/c/CMakeLists.txt
+++ b/tests/test/c/CMakeLists.txt
@@ -31,8 +31,8 @@ IF (TD_LINUX)
   #add_executable(createTablePerformance createTablePerformance.c)
   #target_link_libraries(createTablePerformance taos_static tutil common pthread)
 
-  #add_executable(createNormalTable createNormalTable.c)
-  #target_link_libraries(createNormalTable taos_static tutil common pthread)
+  add_executable(createNormalTable createNormalTable.c)
+  target_link_libraries(createNormalTable taos_static tutil common pthread)
 
   #add_executable(queryPerformance queryPerformance.c)
   #target_link_libraries(queryPerformance taos_static tutil common pthread)
@@ -45,5 +45,8 @@ IF (TD_LINUX)
 
   #add_executable(invalidTableId invalidTableId.c)
   #target_link_libraries(invalidTableId taos_static tutil common pthread)
+
+  add_executable(hashIterator hashIterator.c)
+  target_link_libraries(hashIterator taos_static tutil common pthread)
 ENDIF()
 
diff --git a/tests/test/c/hashIterator.c b/tests/test/c/hashIterator.c
new file mode 100644
index 0000000000..cbd8a0895e
--- /dev/null
+++ b/tests/test/c/hashIterator.c
@@ -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/>.
+ */
+
+#define _DEFAULT_SOURCE
+#include "os.h"
+#include "taos.h"
+#include "tulog.h"
+#include "tutil.h"
+#include "hash.h"
+
+typedef struct HashTestRow {
+  int32_t keySize;
+  char    key[100];
+} HashTestRow;
+
+int main(int argc, char *argv[]) {
+  _hash_fn_t hashFp = taosGetDefaultHashFunction(TSDB_DATA_TYPE_BINARY);
+  void *     hashHandle = taosHashInit(100, hashFp, true, HASH_ENTRY_LOCK);
+
+  pPrint("insert 3 rows to hash");
+  for (int32_t t = 0; t < 3; ++t) {
+    HashTestRow row = {0};
+    row.keySize = sprintf(row.key, "0.db.st%d", t);
+
+    taosHashPut(hashHandle, row.key, row.keySize, &row, sizeof(HashTestRow));
+  }
+
+  pPrint("start iterator");
+  HashTestRow *row = taosHashIterate(hashHandle, NULL);
+  while (row) {
+    pPrint("drop key:%s", row->key);
+    taosHashRemove(hashHandle, row->key, row->keySize);
+
+    pPrint("get rows from hash");
+    for (int32_t t = 0; t < 3; ++t) {
+      HashTestRow r = {0};
+      r.keySize = sprintf(r.key, "0.db.st%d", t);
+
+      void *result = taosHashGet(hashHandle, r.key, r.keySize);
+      pPrint("get key:%s result:%p", r.key, result);
+    }
+
+    //Before getting the next iterator, the object just deleted can be obtained
+    row = taosHashIterate(hashHandle, row);
+  }
+
+  pPrint("stop iterator");
+  taosHashCancelIterate(hashHandle, row);
+
+  pPrint("get rows from hash");
+  for (int32_t t = 0; t < 3; ++t) {
+    HashTestRow r = {0};
+    r.keySize = sprintf(r.key, "0.db.st%d", t);
+
+    void *result = taosHashGet(hashHandle, r.key, r.keySize);
+    pPrint("get key:%s result:%p", r.key, result);
+  }
+
+  return 0;
+}
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