diff --git a/src/client/src/tscFunctionImpl.c b/src/client/src/tscFunctionImpl.c
index c1944e96c94372f19e9fc499630cd94083ac30fa..6fb8df24441907fde789748bfeeaa6a6eb67fac3 100644
--- a/src/client/src/tscFunctionImpl.c
+++ b/src/client/src/tscFunctionImpl.c
@@ -1691,10 +1691,7 @@ static void last_function(SQLFunctionCtx *pCtx) {
 }
 
 static void last_function_f(SQLFunctionCtx *pCtx, int32_t index) {
-  if (pCtx->order == TSDB_ORDER_ASC) {
-    return;
-  }
-  
+  assert(pCtx->order != TSDB_ORDER_ASC);
   void *pData = GET_INPUT_CHAR_INDEX(pCtx, index);
   if (pCtx->hasNull && isNull(pData, pCtx->inputType)) {
     return;
@@ -2912,7 +2909,7 @@ static void leastsquares_finalizer(SQLFunctionCtx *pCtx) {
 }
 
 static void date_col_output_function(SQLFunctionCtx *pCtx) {
-  if (pCtx->scanFlag == SUPPLEMENTARY_SCAN) {
+  if (pCtx->scanFlag == REVERSE_SCAN) {
     return;
   }
   
@@ -2969,11 +2966,12 @@ static void tag_project_function(SQLFunctionCtx *pCtx) {
     char* output = pCtx->aOutputBuf;
   
     if (pCtx->tag.nType == TSDB_DATA_TYPE_BINARY || pCtx->tag.nType == TSDB_DATA_TYPE_NCHAR) {
-      *(int16_t*) output = pCtx->tag.nLen;
-      output += VARSTR_HEADER_SIZE;
+      varDataSetLen(output, pCtx->tag.nLen);
+      tVariantDump(&pCtx->tag, varDataVal(output), pCtx->outputType);
+    } else {
+      tVariantDump(&pCtx->tag, output, pCtx->outputType);
     }
     
-    tVariantDump(&pCtx->tag, output, pCtx->outputType);
     pCtx->aOutputBuf += pCtx->outputBytes;
   }
 }
diff --git a/src/client/src/tscSQLParser.c b/src/client/src/tscSQLParser.c
index 4cc03f7ad9d04c4bd48c44d2f0563edecdc394cf..4ef24e7335e55ad205c7aba3c7ccd05bb9e1d6ee 100644
--- a/src/client/src/tscSQLParser.c
+++ b/src/client/src/tscSQLParser.c
@@ -5911,7 +5911,7 @@ int32_t exprTreeFromSqlExpr(tExprNode **pExpr, const tSQLExpr* pSqlExpr, SArray*
   }
   
   if (pSqlExpr->pLeft == NULL) {
-    if (pSqlExpr->nSQLOptr >= TK_TINYINT && pSqlExpr->nSQLOptr <= TK_DOUBLE) {
+    if (pSqlExpr->nSQLOptr >= TK_BOOL && pSqlExpr->nSQLOptr <= TK_STRING) {
       *pExpr = calloc(1, sizeof(tExprNode));
       (*pExpr)->nodeType = TSQL_NODE_VALUE;
       (*pExpr)->pVal = calloc(1, sizeof(tVariant));
diff --git a/src/client/src/tscServer.c b/src/client/src/tscServer.c
index 119a84e964f70bfa061d1b245e483eaf2210dd25..8efe89d28ab497ea7a442b412845d9b54172dce6 100644
--- a/src/client/src/tscServer.c
+++ b/src/client/src/tscServer.c
@@ -492,13 +492,15 @@ int tscBuildFetchMsg(SSqlObj *pSql, SSqlInfo *pInfo) {
   pMsg += sizeof(pQueryInfo->type);
 
   // todo valid the vgroupId at the client side
-  if (UTIL_TABLE_IS_SUPERTABLE(pQueryInfo->pTableMetaInfo[0])) {
-    SVgroupsInfo* pVgroupInfo = pQueryInfo->pTableMetaInfo[0]->vgroupList;
-    assert(pVgroupInfo->numOfVgroups == 1); // todo fix me
+  STableMetaInfo* pTableMetaInfo = tscGetMetaInfo(pQueryInfo, 0);
+  
+  if (UTIL_TABLE_IS_SUPERTABLE(pTableMetaInfo)) {
+    int32_t vgIndex = pTableMetaInfo->vgroupIndex;
     
-    pRetrieveMsg->header.vgId = htonl(pVgroupInfo->vgroups[0].vgId);
+    SVgroupsInfo* pVgroupInfo = pTableMetaInfo->vgroupList;
+    pRetrieveMsg->header.vgId = htonl(pVgroupInfo->vgroups[vgIndex].vgId);
   } else {
-    STableMeta* pTableMeta = pQueryInfo->pTableMetaInfo[0]->pTableMeta;
+    STableMeta* pTableMeta = pTableMetaInfo->pTableMeta;
     pRetrieveMsg->header.vgId = htonl(pTableMeta->vgroupInfo.vgId);
   }
   
diff --git a/src/client/src/tscSubquery.c b/src/client/src/tscSubquery.c
index d3a81adca6dc8fa48dcbbff8d95960f43e0caa1d..7a1c08d0563ecabd9d4a3cbd00ea622d8e5fe02b 100644
--- a/src/client/src/tscSubquery.c
+++ b/src/client/src/tscSubquery.c
@@ -1436,8 +1436,8 @@ void tscHandleSubqueryError(SRetrieveSupport *trsupport, SSqlObj *pSql, int numO
       return;
     } else {  // reach the maximum retry count, abort
       atomic_val_compare_exchange_32(&pState->code, TSDB_CODE_SUCCESS, numOfRows);
-      tscError("%p sub:%p retrieve failed,code:%d,orderOfSub:%d failed.no more retry,set global code:%d", pPObj, pSql,
-               numOfRows, subqueryIndex, tstrerror(pState->code));
+      tscError("%p sub:%p retrieve failed,code:%s,orderOfSub:%d failed.no more retry,set global code:%s", pPObj, pSql,
+               tstrerror(numOfRows), subqueryIndex, tstrerror(pState->code));
     }
   }
   
@@ -1450,7 +1450,7 @@ void tscHandleSubqueryError(SRetrieveSupport *trsupport, SSqlObj *pSql, int numO
   }
   
   // all subqueries are failed
-  tscError("%p retrieve from %d vnode(s) completed,code:%d.FAILED.", pPObj, pState->numOfTotal, pState->code);
+  tscError("%p retrieve from %d vnode(s) completed,code:%s.FAILED.", pPObj, pState->numOfTotal, tstrerror(pState->code));
   pPObj->res.code = pState->code;
   
   // release allocated resource
diff --git a/src/client/src/tscUtil.c b/src/client/src/tscUtil.c
index dd3cb76cbf40876718786dae14dbb5a7b263d8c7..00afb977fd9390e9f063a0dd72a9ac74073d3c9f 100644
--- a/src/client/src/tscUtil.c
+++ b/src/client/src/tscUtil.c
@@ -1675,10 +1675,7 @@ STableMetaInfo* tscAddTableMetaInfo(SQueryInfo* pQueryInfo, const char* name, ST
   pTableMetaInfo->pTableMeta = pTableMeta;
   
   if (vgroupList != NULL) {
-    assert(vgroupList->numOfVgroups == 1);  // todo fix me
-    
     size_t size = sizeof(SVgroupsInfo) + sizeof(SCMVgroupInfo) * vgroupList->numOfVgroups;
-    
     pTableMetaInfo->vgroupList = malloc(size);
     memcpy(pTableMetaInfo->vgroupList, vgroupList, size);
   }
diff --git a/src/common/inc/tdataformat.h b/src/common/inc/tdataformat.h
index ec52bcd2ae34acf04806727fddf5a24dfcb260ef..51a5dad4869f3d464d83397157d9fda4482dc6a9 100644
--- a/src/common/inc/tdataformat.h
+++ b/src/common/inc/tdataformat.h
@@ -115,10 +115,8 @@ static FORCE_INLINE void *tdGetRowDataOfCol(SDataRow row, int8_t type, int32_t o
     case TSDB_DATA_TYPE_BINARY:
     case TSDB_DATA_TYPE_NCHAR:
       return POINTER_SHIFT(row, *(VarDataOffsetT *)POINTER_SHIFT(row, offset));
-      break;
     default:
       return POINTER_SHIFT(row, offset);
-      break;
   }
 }
 
diff --git a/src/inc/taosdef.h b/src/inc/taosdef.h
index 571b551368c8139a7527965deb1549ac479866a4..33a0e4f2c6e12b7e67e6ba58fb833846f05e9044 100644
--- a/src/inc/taosdef.h
+++ b/src/inc/taosdef.h
@@ -36,6 +36,11 @@ extern "C" {
 typedef int32_t VarDataOffsetT;
 typedef int16_t VarDataLenT;
 
+typedef struct tstr {
+  VarDataLenT len;
+  char        data[];
+} tstr;
+
 #define VARSTR_HEADER_SIZE  sizeof(VarDataLenT)
 
 #define varDataLen(v)       ((VarDataLenT *)(v))[0]
@@ -74,10 +79,10 @@ extern const int32_t TYPE_BYTES[11];
 #define TSDB_DATA_NULL_STR              "NULL"
 #define TSDB_DATA_NULL_STR_L            "null"
 
-#define TSDB_TRUE 1
-#define TSDB_FALSE 0
-#define TSDB_OK 0
-#define TSDB_ERR -1
+#define TSDB_TRUE   1
+#define TSDB_FALSE  0
+#define TSDB_OK     0
+#define TSDB_ERR   -1
 
 #define TS_PATH_DELIMITER "."
 
diff --git a/src/inc/tsdb.h b/src/inc/tsdb.h
index f4242fbe1fbb72fbbf1e189100c6d9e0fd3d4676..77a0e23af9400efc601badc974998ec83232e4ad 100644
--- a/src/inc/tsdb.h
+++ b/src/inc/tsdb.h
@@ -102,7 +102,7 @@ int  tsdbTableSetSName(STableCfg *config, char *sname, bool dup);
 void tsdbClearTableCfg(STableCfg *config);
 
 int32_t tsdbGetTableTagVal(TsdbRepoT *repo, STableId* id, int32_t colId, int16_t *type, int16_t *bytes, char **val);
-int32_t tsdbGetTableName(TsdbRepoT *repo, STableId* id, char** name);
+char* tsdbGetTableName(TsdbRepoT *repo, const STableId* id, int16_t* bytes);
 
 int   tsdbCreateTable(TsdbRepoT *repo, STableCfg *pCfg);
 int   tsdbDropTable(TsdbRepoT *pRepo, STableId tableId);
diff --git a/src/query/inc/queryExecutor.h b/src/query/inc/queryExecutor.h
index 906dadb31798b2a48b0ebb142c613511a49dee65..2088e5a49ddd4d249effdc915234c70efff961cc 100644
--- a/src/query/inc/queryExecutor.h
+++ b/src/query/inc/queryExecutor.h
@@ -110,6 +110,14 @@ typedef struct STableQueryInfo {  // todo merge with the STableQueryInfo struct
   SWindowResInfo windowResInfo;
 } STableQueryInfo;
 
+typedef struct SQueryCostSummary {
+} SQueryCostSummary;
+
+typedef struct SGroupItem {
+  STableId id;
+  STableQueryInfo* info;
+} SGroupItem;
+
 typedef struct SQuery {
   int16_t           numOfCols;
   int16_t           numOfTags;
@@ -131,17 +139,15 @@ typedef struct SQuery {
   SColumnInfo*      tagColList;
   int32_t           numOfFilterCols;
   int64_t*          defaultVal;
-  TSKEY             lastKey;
+//  TSKEY             lastKey;
   uint32_t          status;  // query status
   SResultRec        rec;
   int32_t           pos;
   SData**           sdata;
+  STableQueryInfo*  current;
   SSingleColumnFilterInfo* pFilterInfo;
 } SQuery;
 
-typedef struct SQueryCostSummary {
-} SQueryCostSummary;
-
 typedef struct SQueryRuntimeEnv {
   SResultInfo*       resultInfo;  // todo refactor to merge with SWindowResInfo
   SQuery*            pQuery;
diff --git a/src/query/inc/tsqlfunction.h b/src/query/inc/tsqlfunction.h
index a92f401323ad4d63cf9141d9fb7c0cdb569f6628..a11c03f2c0da8db902d6f24ba70fea56b37385f2 100644
--- a/src/query/inc/tsqlfunction.h
+++ b/src/query/inc/tsqlfunction.h
@@ -104,7 +104,7 @@ extern "C" {
 
 enum {
   MASTER_SCAN           = 0x0u,
-  SUPPLEMENTARY_SCAN    = 0x1u,
+  REVERSE_SCAN          = 0x1u,
   REPEAT_SCAN           = 0x2u,  //repeat scan belongs to the master scan
   FIRST_STAGE_MERGE     = 0x10u,
   SECONDARY_STAGE_MERGE = 0x20u,
diff --git a/src/query/src/qast.c b/src/query/src/qast.c
index 98682ce778976a1472317d8e8adf1c289411f862..01099b2c3bbc430403eecdcc706984ced76659db 100644
--- a/src/query/src/qast.c
+++ b/src/query/src/qast.c
@@ -552,18 +552,18 @@ static void tQueryIndexColumn(SSkipList* pSkipList, tQueryInfo* pQueryInfo, SArr
   if (cond.start != NULL) {
     int32_t optr = cond.start->optr;
     
-    if (optr == TSDB_RELATION_EQUAL) {
+    if (optr == TSDB_RELATION_EQUAL) {   // equals
       while(tSkipListIterNext(iter)) {
         SSkipListNode* pNode = tSkipListIterGet(iter);
 
         int32_t ret = pQueryInfo->compare(SL_GET_NODE_KEY(pSkipList, pNode), cond.start->v);
-        if (ret == 0) {
-          taosArrayPush(result, SL_GET_NODE_DATA(pNode));
-        } else {
+        if (ret != 0) {
           break;
         }
+        
+        taosArrayPush(result, SL_GET_NODE_DATA(pNode));
       }
-    } else if (optr == TSDB_RELATION_GREATER || optr == TSDB_RELATION_GREATER_EQUAL) {
+    } else if (optr == TSDB_RELATION_GREATER || optr == TSDB_RELATION_GREATER_EQUAL) { // greater equal
       bool comp = true;
       int32_t ret = 0;
       
@@ -582,8 +582,33 @@ static void tQueryIndexColumn(SSkipList* pSkipList, tQueryInfo* pQueryInfo, SArr
           comp = false;
         }
       }
-    } else if (optr == TSDB_RELATION_NOT_EQUAL) {
-      assert(0);
+    } else if (optr == TSDB_RELATION_NOT_EQUAL) {   // not equal
+      bool comp = true;
+      
+      while(tSkipListIterNext(iter)) {
+        SSkipListNode* pNode = tSkipListIterGet(iter);
+        comp = comp && (pQueryInfo->compare(SL_GET_NODE_KEY(pSkipList, pNode), cond.start->v) == 0);
+        if (comp) {
+          continue;
+        }
+        
+        taosArrayPush(result, SL_GET_NODE_DATA(pNode));
+      }
+      
+      tSkipListDestroyIter(iter);
+  
+      comp = true;
+      iter = tSkipListCreateIterFromVal(pSkipList, (char*) cond.start->v, pSkipList->keyInfo.type, TSDB_ORDER_DESC);
+      while(tSkipListIterNext(iter)) {
+        SSkipListNode* pNode = tSkipListIterGet(iter);
+        comp = comp && (pQueryInfo->compare(SL_GET_NODE_KEY(pSkipList, pNode), cond.start->v) == 0);
+        if (comp) {
+          continue;
+        }
+  
+        taosArrayPush(result, SL_GET_NODE_DATA(pNode));
+      }
+  
     } else {
       assert(0);
     }
@@ -773,8 +798,6 @@ static void tSQLBinaryTraverseOnSkipList(tExprNode *pExpr, SArray *pResult, SSki
   tSkipListDestroyIter(iter);
 }
 
-
-
 static void tQueryIndexlessColumn(SSkipList* pSkipList, tQueryInfo* pQueryInfo, SArray* result) {
   SSkipListIterator* iter = tSkipListCreateIter(pSkipList);
 
@@ -785,7 +808,7 @@ static void tQueryIndexlessColumn(SSkipList* pSkipList, tQueryInfo* pQueryInfo,
     char* pTable = SL_GET_NODE_DATA(pNode);
     
     //todo refactor:
-    char* name = (*(STable**) pTable)->name;
+    tstr* name = ((STableIndexElem*) pTable)->pTable->name;
 //    char* name = NULL;
 //    tsdbGetTableName(tsdb, pTable, &name);
 
diff --git a/src/query/src/queryExecutor.c b/src/query/src/queryExecutor.c
index 0ffc665e553c6f19046057d0a79a7be1678ef693..52cfa582d080fed6816fd32f3d9457f5a946e851 100644
--- a/src/query/src/queryExecutor.c
+++ b/src/query/src/queryExecutor.c
@@ -40,9 +40,9 @@
 #define QUERY_IS_ASC_QUERY(q) (GET_FORWARD_DIRECTION_FACTOR((q)->order.order) == QUERY_ASC_FORWARD_STEP)
 
 #define IS_MASTER_SCAN(runtime)        ((runtime)->scanFlag == MASTER_SCAN)
-#define IS_REVERSE_SCAN(runtime)       ((runtime)->scanFlag == SUPPLEMENTARY_SCAN)
+#define IS_REVERSE_SCAN(runtime)       ((runtime)->scanFlag == REVERSE_SCAN)
 #define SET_MASTER_SCAN_FLAG(runtime)  ((runtime)->scanFlag = MASTER_SCAN)
-#define SET_REVERSE_SCAN_FLAG(runtime) ((runtime)->scanFlag = SUPPLEMENTARY_SCAN)
+#define SET_REVERSE_SCAN_FLAG(runtime) ((runtime)->scanFlag = REVERSE_SCAN)
 
 #define GET_QINFO_ADDR(x) ((void *)((char *)(x)-offsetof(SQInfo, runtimeEnv)))
 
@@ -96,11 +96,6 @@ typedef struct {
   STSCursor   cur;
 } SQueryStatusInfo;
 
-typedef struct SGroupItem {
-  STableId id;
-  STableQueryInfo* info;
-} SGroupItem;
-
 static void setQueryStatus(SQuery *pQuery, int8_t status);
 static bool isIntervalQuery(SQuery *pQuery) { return pQuery->intervalTime > 0; }
 
@@ -121,7 +116,7 @@ static bool hasMainOutput(SQuery *pQuery);
 static void createTableQueryInfo(SQInfo *pQInfo);
 static void buildTagQueryResult(SQInfo *pQInfo);
 
-static int32_t setAdditionalInfo(SQInfo *pQInfo, STableId *pTaleId, STableQueryInfo *pTableQueryInfo);
+static int32_t setAdditionalInfo(SQInfo *pQInfo, STableId *pTableId, STableQueryInfo *pTableQueryInfo);
 static int32_t flushFromResultBuf(SQInfo *pQInfo);
 
 bool getNeighborPoints(SQInfo *pQInfo, void *pMeterObj, SPointInterpoSupporter *pPointInterpSupporter) {
@@ -428,9 +423,10 @@ static bool hasNullValue(SQuery *pQuery, int32_t col, SDataBlockInfo *pDataBlock
     return false;
   }
 
-  *pColStatis = NULL;
   if (pStatis != NULL) {
     *pColStatis = getStatisInfo(pQuery, pStatis, pDataBlockInfo, col);
+  } else {
+    *pColStatis = NULL;
   }
 
   if ((*pColStatis) != NULL && (*pColStatis)->numOfNull == 0) {
@@ -620,8 +616,8 @@ static void doCheckQueryCompleted(SQueryRuntimeEnv *pRuntimeEnv, TSKEY lastKey,
   }
 
   // query completed
-  if ((lastKey >= pQuery->window.ekey && QUERY_IS_ASC_QUERY(pQuery)) ||
-      (lastKey <= pQuery->window.ekey && !QUERY_IS_ASC_QUERY(pQuery))) {
+  if ((lastKey >= pQuery->current->win.ekey && QUERY_IS_ASC_QUERY(pQuery)) ||
+      (lastKey <= pQuery->current->win.ekey && !QUERY_IS_ASC_QUERY(pQuery))) {
     closeAllTimeWindow(pWindowResInfo);
 
     pWindowResInfo->curIndex = pWindowResInfo->size - 1;
@@ -661,22 +657,22 @@ static void doCheckQueryCompleted(SQueryRuntimeEnv *pRuntimeEnv, TSKEY lastKey,
       setQueryStatus(pQuery, QUERY_RESBUF_FULL);
     }
 
-    qTrace("QInfo:%p total window:%d, closed:%d", GET_QINFO_ADDR(pQuery), pWindowResInfo->size, n);
+    qTrace("QInfo:%p total window:%d, closed:%d", GET_QINFO_ADDR(pRuntimeEnv), pWindowResInfo->size, n);
   }
 
   assert(pWindowResInfo->prevSKey != 0);
 }
 
 static int32_t getNumOfRowsInTimeWindow(SQuery *pQuery, SDataBlockInfo *pDataBlockInfo, TSKEY *pPrimaryColumn,
-                                        int32_t startPos, TSKEY ekey, __block_search_fn_t searchFn,
-                                        bool updateLastKey) {
+                                        int32_t startPos, TSKEY ekey, __block_search_fn_t searchFn, bool updateLastKey) {
   assert(startPos >= 0 && startPos < pDataBlockInfo->rows);
 
   int32_t num = -1;
   int32_t order = pQuery->order.order;
-
   int32_t step = GET_FORWARD_DIRECTION_FACTOR(order);
 
+  STableQueryInfo* item = pQuery->current;
+  
   if (QUERY_IS_ASC_QUERY(pQuery)) {
     if (ekey < pDataBlockInfo->window.ekey) {
       num = getForwardStepsInBlock(pDataBlockInfo->rows, searchFn, ekey, startPos, order, pPrimaryColumn);
@@ -684,13 +680,13 @@ static int32_t getNumOfRowsInTimeWindow(SQuery *pQuery, SDataBlockInfo *pDataBlo
         assert(ekey < pPrimaryColumn[startPos]);
       } else {
         if (updateLastKey) {
-          pQuery->lastKey = pPrimaryColumn[startPos + (num - 1)] + step;
+          item->lastKey = pPrimaryColumn[startPos + (num - 1)] + step;
         }
       }
     } else {
       num = pDataBlockInfo->rows - startPos;
       if (updateLastKey) {
-        pQuery->lastKey = pDataBlockInfo->window.ekey + step;
+        item->lastKey = pDataBlockInfo->window.ekey + step;
       }
     }
   } else {  // desc
@@ -700,13 +696,13 @@ static int32_t getNumOfRowsInTimeWindow(SQuery *pQuery, SDataBlockInfo *pDataBlo
         assert(ekey > pPrimaryColumn[startPos]);
       } else {
         if (updateLastKey) {
-          pQuery->lastKey = pPrimaryColumn[startPos - (num - 1)] + step;
+          item->lastKey = pPrimaryColumn[startPos - (num - 1)] + step;
         }
       }
     } else {
       num = startPos + 1;
       if (updateLastKey) {
-        pQuery->lastKey = pDataBlockInfo->window.skey + step;
+        item->lastKey = pDataBlockInfo->window.skey + step;
       }
     }
   }
@@ -820,7 +816,21 @@ static TSKEY reviseWindowEkey(SQuery *pQuery, STimeWindow *pWindow) {
   return ekey;
 }
 
-char *getDataBlocks(SQueryRuntimeEnv *pRuntimeEnv, SArithmeticSupport *sas, int32_t col, int32_t size,
+//todo binary search
+static void* getDataBlockImpl(SArray* pDataBlock, int32_t colId) {
+  int32_t numOfCols = taosArrayGetSize(pDataBlock);
+  
+  for (int32_t i = 0; i < numOfCols; ++i) {
+    SColumnInfoData *p = taosArrayGet(pDataBlock, i);
+    if (colId == p->info.colId) {
+      return p->pData;
+    }
+  }
+  
+  return NULL;
+}
+
+static char *getDataBlock(SQueryRuntimeEnv *pRuntimeEnv, SArithmeticSupport *sas, int32_t col, int32_t size,
                     SArray *pDataBlock) {
   char *dataBlock = NULL;
   SQuery *pQuery = pRuntimeEnv->pQuery;
@@ -867,20 +877,7 @@ char *getDataBlocks(SQueryRuntimeEnv *pRuntimeEnv, SArithmeticSupport *sas, int3
     if (TSDB_COL_IS_TAG(pCol->flag) || pDataBlock == NULL) {
       dataBlock = NULL;
     } else {
-      /*
-       *  the colIndex is acquired from the first meter of all qualified meters in this vnode during query prepare
-       * stage, the remain meter may not have the required column in cache actually. So, the validation of required
-       * column in cache with the corresponding meter schema is reinforced.
-       */
-      int32_t numOfCols = taosArrayGetSize(pDataBlock);
-      
-      for (int32_t i = 0; i < numOfCols; ++i) {
-        SColumnInfoData *p = taosArrayGet(pDataBlock, i);
-        if (pCol->colId == p->info.colId) {
-          dataBlock = p->pData;
-          break;
-        }
-      }
+      dataBlock = getDataBlockImpl(pDataBlock, pCol->colId);
     }
   }
 
@@ -904,8 +901,8 @@ static void blockwiseApplyFunctions(SQueryRuntimeEnv *pRuntimeEnv, SDataStatis *
   SQuery *        pQuery = pRuntimeEnv->pQuery;
 
   SColumnInfoData *pColInfo = NULL;
-  TSKEY *          primaryKeyCol = NULL;
-
+  
+  TSKEY *primaryKeyCol = NULL;
   if (pDataBlock != NULL) {
     pColInfo = taosArrayGet(pDataBlock, 0);
     primaryKeyCol = (TSKEY *)(pColInfo->pData);
@@ -919,7 +916,7 @@ static void blockwiseApplyFunctions(SQueryRuntimeEnv *pRuntimeEnv, SDataStatis *
     SDataStatis *tpField = NULL;
 
     bool  hasNull = hasNullValue(pQuery, k, pDataBlockInfo, pStatis, &tpField);
-    char *dataBlock = getDataBlocks(pRuntimeEnv, &sasArray[k], k, pDataBlockInfo->rows, pDataBlock);
+    char *dataBlock = getDataBlock(pRuntimeEnv, &sasArray[k], k, pDataBlockInfo->rows, pDataBlock);
 
     setExecParams(pQuery, &pCtx[k], dataBlock, primaryKeyCol, pDataBlockInfo->rows, functionId, tpField, hasNull,
                   &sasArray[k], pRuntimeEnv->scanFlag);
@@ -1095,15 +1092,20 @@ static int32_t doTSJoinFilter(SQueryRuntimeEnv *pRuntimeEnv, int32_t offset) {
 
 static bool functionNeedToExecute(SQueryRuntimeEnv *pRuntimeEnv, SQLFunctionCtx *pCtx, int32_t functionId) {
   SResultInfo *pResInfo = GET_RES_INFO(pCtx);
-
+  SQuery* pQuery = pRuntimeEnv->pQuery;
+  
   if (pResInfo->complete || functionId == TSDB_FUNC_TAG_DUMMY || functionId == TSDB_FUNC_TS_DUMMY) {
     return false;
   }
 
+  if (functionId == TSDB_FUNC_LAST_DST || functionId == TSDB_FUNC_LAST) {
+    return !QUERY_IS_ASC_QUERY(pQuery);
+  } else if (functionId == TSDB_FUNC_FIRST_DST || functionId == TSDB_FUNC_FIRST) {
+    return QUERY_IS_ASC_QUERY(pQuery);
+  }
+  
   // in the supplementary scan, only the following functions need to be executed
-  if (IS_REVERSE_SCAN(pRuntimeEnv) &&
-      !(functionId == TSDB_FUNC_LAST_DST || functionId == TSDB_FUNC_FIRST_DST || functionId == TSDB_FUNC_FIRST ||
-        functionId == TSDB_FUNC_LAST || functionId == TSDB_FUNC_TAG || functionId == TSDB_FUNC_TS)) {
+  if (IS_REVERSE_SCAN(pRuntimeEnv)) {// && (functionId == TSDB_FUNC_TAG || functionId == TSDB_FUNC_TS)) {
     return false;
   }
 
@@ -1115,9 +1117,10 @@ static void rowwiseApplyFunctions(SQueryRuntimeEnv *pRuntimeEnv, SDataStatis *pS
   SQLFunctionCtx *pCtx = pRuntimeEnv->pCtx;
   
   SQuery *pQuery = pRuntimeEnv->pQuery;
+  STableQueryInfo* item = pQuery->current;
+  
   TSKEY  *primaryKeyCol = (TSKEY*) ((SColumnInfoData *)taosArrayGet(pDataBlock, 0))->pData;
-
-  bool groupbyStateValue = isGroupbyNormalCol(pQuery->pGroupbyExpr);
+  bool    groupbyStateValue = isGroupbyNormalCol(pQuery->pGroupbyExpr);
   SArithmeticSupport *sasArray = calloc((size_t)pQuery->numOfOutput, sizeof(SArithmeticSupport));
 
   int16_t type = 0;
@@ -1134,7 +1137,7 @@ static void rowwiseApplyFunctions(SQueryRuntimeEnv *pRuntimeEnv, SDataStatis *pS
     SDataStatis *pColStatis = NULL;
 
     bool  hasNull = hasNullValue(pQuery, k, pDataBlockInfo, pStatis, &pColStatis);
-    char *dataBlock = getDataBlocks(pRuntimeEnv, &sasArray[k], k, pDataBlockInfo->rows, pDataBlock);
+    char *dataBlock = getDataBlock(pRuntimeEnv, &sasArray[k], k, pDataBlockInfo->rows, pDataBlock);
 
     setExecParams(pQuery, &pCtx[k], dataBlock, primaryKeyCol, pDataBlockInfo->rows, functionId, pColStatis, hasNull,
                   &sasArray[k], pRuntimeEnv->scanFlag);
@@ -1143,7 +1146,8 @@ static void rowwiseApplyFunctions(SQueryRuntimeEnv *pRuntimeEnv, SDataStatis *pS
   // set the input column data
   for (int32_t k = 0; k < pQuery->numOfFilterCols; ++k) {
     SSingleColumnFilterInfo *pFilterInfo = &pQuery->pFilterInfo[k];
-    pFilterInfo->pData = getDataBlocks(pRuntimeEnv, &sasArray[k], pFilterInfo->info.colId, pDataBlockInfo->rows, pDataBlock);
+    pFilterInfo->pData = getDataBlockImpl(pDataBlock, pFilterInfo->info.colId);
+    assert(pFilterInfo->pData != NULL);
   }
 
   int32_t step = GET_FORWARD_DIRECTION_FACTOR(pQuery->order.order);
@@ -1157,10 +1161,10 @@ static void rowwiseApplyFunctions(SQueryRuntimeEnv *pRuntimeEnv, SDataStatis *pS
   }
 
   int32_t j = 0;
-  TSKEY   lastKey = -1;
-
+  int32_t offset = -1;
+  
   for (j = 0; j < pDataBlockInfo->rows; ++j) {
-    int32_t offset = GET_COL_DATA_POS(pQuery, j, step);
+    offset = GET_COL_DATA_POS(pQuery, j, step);
 
     if (pRuntimeEnv->pTSBuf != NULL) {
       int32_t r = doTSJoinFilter(pRuntimeEnv, offset);
@@ -1194,7 +1198,6 @@ static void rowwiseApplyFunctions(SQueryRuntimeEnv *pRuntimeEnv, SDataStatis *pS
       SWindowStatus *pStatus = getTimeWindowResStatus(pWindowResInfo, curTimeWindow(pWindowResInfo));
       doRowwiseApplyFunctions(pRuntimeEnv, pStatus, &win, offset);
 
-      lastKey = ts;
       STimeWindow nextWin = win;
       int32_t     index = pWindowResInfo->curIndex;
 
@@ -1223,17 +1226,14 @@ static void rowwiseApplyFunctions(SQueryRuntimeEnv *pRuntimeEnv, SDataStatis *pS
     } else {  // other queries
       // decide which group this rows belongs to according to current state value
       if (groupbyStateValue) {
-        char *stateVal = groupbyColumnData + bytes * offset;
+        char *val = groupbyColumnData + bytes * offset;
 
-        int32_t ret = setGroupResultOutputBuf(pRuntimeEnv, stateVal, type, bytes);
+        int32_t ret = setGroupResultOutputBuf(pRuntimeEnv, val, type, bytes);
         if (ret != TSDB_CODE_SUCCESS) {  // null data, too many state code
           continue;
         }
       }
 
-      // update the lastKey
-      lastKey = primaryKeyCol[offset];
-
       // all startOffset are identical
       offset -= pCtx[0].startOffset;
 
@@ -1254,7 +1254,7 @@ static void rowwiseApplyFunctions(SQueryRuntimeEnv *pRuntimeEnv, SDataStatis *pS
     }
   }
   
-  pQuery->lastKey = lastKey + step;
+  item->lastKey = primaryKeyCol[offset] + step;
   
   // todo refactor: extract method
   for(int32_t i = 0; i < pQuery->numOfOutput; ++i) {
@@ -1269,10 +1269,12 @@ static void rowwiseApplyFunctions(SQueryRuntimeEnv *pRuntimeEnv, SDataStatis *pS
 }
 
 static int32_t tableApplyFunctionsOnBlock(SQueryRuntimeEnv *pRuntimeEnv, SDataBlockInfo *pDataBlockInfo,
-                                          SDataStatis *pStatis, __block_search_fn_t searchFn,
-                                          SWindowResInfo *pWindowResInfo, SArray *pDataBlock) {
+                                          SDataStatis *pStatis, __block_search_fn_t searchFn, SArray *pDataBlock) {
   SQuery *pQuery = pRuntimeEnv->pQuery;
-
+  
+  STableQueryInfo* pTableQInfo = pQuery->current;
+  SWindowResInfo*  pWindowResInfo = &pRuntimeEnv->windowResInfo;
+  
   if (pQuery->numOfFilterCols > 0 || pRuntimeEnv->pTSBuf != NULL || isGroupbyNormalCol(pQuery->pGroupbyExpr)) {
     rowwiseApplyFunctions(pRuntimeEnv, pStatis, pDataBlockInfo, pWindowResInfo, pDataBlock);
   } else {
@@ -1280,7 +1282,7 @@ static int32_t tableApplyFunctionsOnBlock(SQueryRuntimeEnv *pRuntimeEnv, SDataBl
   }
 
   TSKEY lastKey = QUERY_IS_ASC_QUERY(pQuery) ? pDataBlockInfo->window.ekey : pDataBlockInfo->window.skey;
-  pQuery->lastKey = lastKey + GET_FORWARD_DIRECTION_FACTOR(pQuery->order.order);
+  pTableQInfo->lastKey = lastKey + GET_FORWARD_DIRECTION_FACTOR(pQuery->order.order);
 
   doCheckQueryCompleted(pRuntimeEnv, lastKey, pWindowResInfo);
 
@@ -1746,73 +1748,6 @@ static UNUSED_FUNC bool doSetDataInfo(SQInfo *pQInfo, SPointInterpoSupporter *pP
   }
 }
 
-// TODO refactor code, the best way to implement the last_row is utilizing the iterator
-bool normalizeUnBoundLastRowQuery(SQInfo *pQInfo, SPointInterpoSupporter *pPointInterpSupporter) {
-#if 0
-  SQueryRuntimeEnv *pRuntimeEnv = &pQInfo->runtimeEnv;
-
-  SQuery *   pQuery = pRuntimeEnv->pQuery;
-  SMeterObj *pMeterObj = pRuntimeEnv->pTabObj;
-
-  assert(!QUERY_IS_ASC_QUERY(pQuery) && notHasQueryTimeRange(pQuery));
-  __block_search_fn_t searchFn = vnodeSearchKeyFunc[pMeterObj->searchAlgorithm];
-
-  TSKEY lastKey = -1;
-
-  pQuery->fileId = -1;
-  vnodeFreeFieldsEx(pRuntimeEnv);
-
-  // keep in-memory cache status in local variables in case that it may be changed by write operation
-  getBasicCacheInfoSnapshot(pQuery, pMeterObj->pCache, pMeterObj->vnode);
-
-  SCacheInfo *pCacheInfo = (SCacheInfo *)pMeterObj->pCache;
-  if (pCacheInfo != NULL && pCacheInfo->cacheBlocks != NULL && pQuery->numOfBlocks > 0) {
-    pQuery->fileId = -1;
-    TSKEY key = pMeterObj->lastKey;
-
-    pQuery->window.skey = key;
-    pQuery->window.ekey = key;
-    pQuery->lastKey = pQuery->window.skey;
-
-    /*
-     * cache block may have been flushed to disk, and no data in cache anymore.
-     * So, copy cache block to local buffer is required.
-     */
-    lastKey = getQueryStartPositionInCache(pRuntimeEnv, &pQuery->slot, &pQuery->pos, false);
-    if (lastKey < 0) {  // data has been flushed to disk, try again search in file
-      lastKey = getQueryPositionForCacheInvalid(pRuntimeEnv, searchFn);
-
-      if (Q_STATUS_EQUAL(pQuery->status, QUERY_NO_DATA_TO_CHECK | QUERY_COMPLETED)) {
-        return false;
-      }
-    }
-  } else {  // no data in cache, try file
-    TSKEY key = pMeterObj->lastKeyOnFile;
-
-    pQuery->window.skey = key;
-    pQuery->window.ekey = key;
-    pQuery->lastKey = pQuery->window.skey;
-
-    bool ret = getQualifiedDataBlock(pMeterObj, pRuntimeEnv, QUERY_RANGE_LESS_EQUAL, searchFn);
-    if (!ret) {  // no data in file, return false;
-      return false;
-    }
-
-    lastKey = getTimestampInDiskBlock(pRuntimeEnv, pQuery->pos);
-  }
-
-  assert(lastKey <= pQuery->window.skey);
-
-  pQuery->window.skey = lastKey;
-  pQuery->window.ekey = lastKey;
-  pQuery->lastKey = pQuery->window.skey;
-
-  return getNeighborPoints(pQInfo, pMeterObj, pPointInterpSupporter);
-#endif
-
-  return true;
-}
-
 static void setScanLimitationByResultBuffer(SQuery *pQuery) {
   if (isTopBottomQuery(pQuery)) {
     pQuery->checkBuffer = 0;
@@ -2327,7 +2262,7 @@ static void getNextTimeWindow(SQuery *pQuery, STimeWindow *pTimeWindow) {
   pTimeWindow->ekey = pTimeWindow->skey + (pQuery->intervalTime - 1);
 }
 
-SArray *loadDataBlockOnDemand(SQueryRuntimeEnv *pRuntimeEnv, SDataBlockInfo *pBlockInfo, SDataStatis **pStatis) {
+SArray *loadDataBlockOnDemand(SQueryRuntimeEnv *pRuntimeEnv, void* pQueryHandle, SDataBlockInfo* pBlockInfo, SDataStatis **pStatis) {
   SQuery *pQuery = pRuntimeEnv->pQuery;
 
   uint32_t r = 0;
@@ -2351,16 +2286,16 @@ SArray *loadDataBlockOnDemand(SQueryRuntimeEnv *pRuntimeEnv, SDataBlockInfo *pBl
     qTrace("QInfo:%p data block ignored, brange:%" PRId64 "-%" PRId64 ", rows:%d", GET_QINFO_ADDR(pRuntimeEnv),
            pBlockInfo->window.skey, pBlockInfo->window.ekey, pBlockInfo->rows);
   } else if (r == BLK_DATA_FILEDS_NEEDED) {
-    if (tsdbRetrieveDataBlockStatisInfo(pRuntimeEnv->pQueryHandle, pStatis) != TSDB_CODE_SUCCESS) {
+    if (tsdbRetrieveDataBlockStatisInfo(pQueryHandle, pStatis) != TSDB_CODE_SUCCESS) {
       //        return DISK_DATA_LOAD_FAILED;
     }
 
     if (*pStatis == NULL) {
-      pDataBlock = tsdbRetrieveDataBlock(pRuntimeEnv->pQueryHandle, NULL);
+      pDataBlock = tsdbRetrieveDataBlock(pQueryHandle, NULL);
     }
   } else {
     assert(r == BLK_DATA_ALL_NEEDED);
-    if (tsdbRetrieveDataBlockStatisInfo(pRuntimeEnv->pQueryHandle, pStatis) != TSDB_CODE_SUCCESS) {
+    if (tsdbRetrieveDataBlockStatisInfo(pQueryHandle, pStatis) != TSDB_CODE_SUCCESS) {
       //        return DISK_DATA_LOAD_FAILED;
     }
 
@@ -2376,7 +2311,7 @@ SArray *loadDataBlockOnDemand(SQueryRuntimeEnv *pRuntimeEnv, SDataBlockInfo *pBl
       //        return DISK_DATA_DISCARDED;
     }
 
-    pDataBlock = tsdbRetrieveDataBlock(pRuntimeEnv->pQueryHandle, NULL);
+    pDataBlock = tsdbRetrieveDataBlock(pQueryHandle, NULL);
   }
 
   return pDataBlock;
@@ -2447,8 +2382,11 @@ int32_t binarySearchForKey(char *pValue, int num, TSKEY key, int order) {
 
 static int64_t doScanAllDataBlocks(SQueryRuntimeEnv *pRuntimeEnv) {
   SQuery *pQuery = pRuntimeEnv->pQuery;
+  STableQueryInfo* pTableQueryInfo = pQuery->current;
+  
   qTrace("QInfo:%p query start, qrange:%" PRId64 "-%" PRId64 ", lastkey:%" PRId64 ", order:%d",
-         GET_QINFO_ADDR(pRuntimeEnv), pQuery->window.skey, pQuery->window.ekey, pQuery->lastKey, pQuery->order.order);
+         GET_QINFO_ADDR(pRuntimeEnv), pTableQueryInfo->win.skey, pTableQueryInfo->win.ekey, pTableQueryInfo->lastKey,
+         pQuery->order.order);
 
   TsdbQueryHandleT pQueryHandle = IS_MASTER_SCAN(pRuntimeEnv)? pRuntimeEnv->pQueryHandle : pRuntimeEnv->pSecQueryHandle;
   while (tsdbNextDataBlock(pQueryHandle)) {
@@ -2479,7 +2417,7 @@ static int64_t doScanAllDataBlocks(SQueryRuntimeEnv *pRuntimeEnv) {
       }
     }
 
-    // in case of prj/diff query, ensure the output buffer is sufficient to accomodate the results of current block
+    // in case of prj/diff query, ensure the output buffer is sufficient to accommodate the results of current block
     if (!isIntervalQuery(pQuery) && !isGroupbyNormalCol(pQuery->pGroupbyExpr) && !isFixedOutputQuery(pQuery)) {
       SResultRec *pRec = &pQuery->rec;
 
@@ -2505,11 +2443,10 @@ static int64_t doScanAllDataBlocks(SQueryRuntimeEnv *pRuntimeEnv) {
     }
 
     SDataStatis *pStatis = NULL;
-    SArray *     pDataBlock = loadDataBlockOnDemand(pRuntimeEnv, &blockInfo, &pStatis);
+    SArray *     pDataBlock = loadDataBlockOnDemand(pRuntimeEnv, pQueryHandle, &blockInfo, &pStatis);
 
     pQuery->pos = QUERY_IS_ASC_QUERY(pQuery) ? 0 : blockInfo.rows - 1;
-    int32_t numOfRes = tableApplyFunctionsOnBlock(pRuntimeEnv, &blockInfo, pStatis, binarySearchForKey,
-                                                  &pRuntimeEnv->windowResInfo, pDataBlock);
+    int32_t numOfRes = tableApplyFunctionsOnBlock(pRuntimeEnv, &blockInfo, pStatis, binarySearchForKey, pDataBlock);
 
     qTrace("QInfo:%p check data block, brange:%" PRId64 "-%" PRId64 ", rows:%d, res:%d", GET_QINFO_ADDR(pRuntimeEnv),
            blockInfo.window.skey, blockInfo.window.ekey, blockInfo.rows, numOfRes);
@@ -2520,7 +2457,7 @@ static int64_t doScanAllDataBlocks(SQueryRuntimeEnv *pRuntimeEnv) {
     }
   }
 
-  // if the result buffer is not full, set the query completed flag
+  // if the result buffer is not full, set the query complete
   if (!Q_STATUS_EQUAL(pQuery->status, QUERY_RESBUF_FULL)) {
     setQueryStatus(pQuery, QUERY_COMPLETED);
   }
@@ -2530,8 +2467,8 @@ static int64_t doScanAllDataBlocks(SQueryRuntimeEnv *pRuntimeEnv) {
       int32_t step = QUERY_IS_ASC_QUERY(pQuery) ? QUERY_ASC_FORWARD_STEP : QUERY_DESC_FORWARD_STEP;
 
       closeAllTimeWindow(&pRuntimeEnv->windowResInfo);
-      removeRedundantWindow(&pRuntimeEnv->windowResInfo, pQuery->lastKey - step, step);
-      pRuntimeEnv->windowResInfo.curIndex = pRuntimeEnv->windowResInfo.size - 1;
+      removeRedundantWindow(&pRuntimeEnv->windowResInfo, pTableQueryInfo->lastKey - step, step);
+      pRuntimeEnv->windowResInfo.curIndex = pRuntimeEnv->windowResInfo.size - 1;  // point to the last time window
     } else {
       assert(Q_STATUS_EQUAL(pQuery->status, QUERY_RESBUF_FULL));
     }
@@ -2540,8 +2477,6 @@ static int64_t doScanAllDataBlocks(SQueryRuntimeEnv *pRuntimeEnv) {
   return 0;
 }
 
-static void updatelastkey(SQuery *pQuery, STableQueryInfo *pTableQInfo) { pTableQInfo->lastKey = pQuery->lastKey; }
-
 /*
  * set tag value in SQLFunctionCtx
  * e.g.,tag information into input buffer
@@ -2554,17 +2489,17 @@ static void doSetTagValueInParam(void *tsdb, STableId* pTableId, int32_t tagColI
   int16_t type = 0;
 
   if (tagColId == TSDB_TBNAME_COLUMN_INDEX) {
-    tsdbGetTableName(tsdb, pTableId, &val);
-    bytes = strnlen(val, TSDB_TABLE_NAME_LEN);
+    val = tsdbGetTableName(tsdb, pTableId, &bytes);
     type = TSDB_DATA_TYPE_BINARY;
+    tVariantCreateFromBinary(param, varDataVal(val), varDataLen(val), type);
   } else {
     tsdbGetTableTagVal(tsdb, pTableId, tagColId, &type, &bytes, &val);
-  }
-  
-  tVariantCreateFromBinary(param, val, bytes, type);
-  
-  if (tagColId == TSDB_TBNAME_COLUMN_INDEX) {
-    tfree(val);
+    
+    if (type == TSDB_DATA_TYPE_BINARY || type == TSDB_DATA_TYPE_NCHAR) {
+      tVariantCreateFromBinary(param, varDataVal(val), varDataLen(val), type);
+    } else {
+      tVariantCreateFromBinary(param, val, bytes, type);
+    }
   }
 }
 
@@ -3082,11 +3017,6 @@ void resetMergeResultBuf(SQuery *pQuery, SQLFunctionCtx *pCtx, SResultInfo *pRes
   }
 }
 
-void setTableDataInfo(STableQueryInfo *pTableQueryInfo, int32_t tableIndex, int32_t groupId) {
-  pTableQueryInfo->groupIdx = groupId;
-  pTableQueryInfo->tableIndex = tableIndex;
-}
-
 static void updateTableQueryInfoForReverseScan(SQuery *pQuery, STableQueryInfo *pTableQueryInfo) {
   if (pTableQueryInfo == NULL) {
     return;
@@ -3132,19 +3062,6 @@ static void disableFuncInReverseScanImpl(SQInfo* pQInfo, SWindowResInfo *pWindow
       }
     }
   }
-  
-  int32_t numOfGroups = taosArrayGetSize(pQInfo->groupInfo.pGroupList);
-  
-  for(int32_t i = 0; i < numOfGroups; ++i) {
-    SArray *group = taosArrayGetP(pQInfo->groupInfo.pGroupList, i);
-    qTrace("QInfo:%p no result in group %d, continue", pQInfo, pQInfo->groupIndex - 1);
-
-    size_t t = taosArrayGetSize(group);
-    for (int32_t j = 0; j < t; ++j) {
-      SGroupItem *item = taosArrayGet(group, j);
-      updateTableQueryInfoForReverseScan(pQuery, item->info);
-    }
-  }
 }
 
 void disableFuncInReverseScan(SQInfo *pQInfo) {
@@ -3170,6 +3087,18 @@ void disableFuncInReverseScan(SQInfo *pQInfo) {
       }
     }
   }
+  
+  int32_t numOfGroups = taosArrayGetSize(pQInfo->groupInfo.pGroupList);
+  
+  for(int32_t i = 0; i < numOfGroups; ++i) {
+    SArray *group = taosArrayGetP(pQInfo->groupInfo.pGroupList, i);
+    
+    size_t t = taosArrayGetSize(group);
+    for (int32_t j = 0; j < t; ++j) {
+      SGroupItem *item = taosArrayGet(group, j);
+      updateTableQueryInfoForReverseScan(pQuery, item->info);
+    }
+  }
 }
 
 void switchCtxOrder(SQueryRuntimeEnv *pRuntimeEnv) {
@@ -3345,13 +3274,14 @@ bool needScanDataBlocksAgain(SQueryRuntimeEnv *pRuntimeEnv) {
 
 static SQueryStatusInfo getQueryStatusInfo(SQueryRuntimeEnv *pRuntimeEnv) {
   SQuery *pQuery = pRuntimeEnv->pQuery;
-
+  STableQueryInfo* pTableQueryInfo = pQuery->current;
+  
   SQueryStatusInfo info = {
-      .status = pQuery->status,
+      .status      = pQuery->status,
       .windowIndex = pRuntimeEnv->windowResInfo.curIndex,
-      .lastKey = pQuery->lastKey,
-      .w = pQuery->window,
-      .curWindow = {.skey = pQuery->lastKey, .ekey = pQuery->window.ekey},
+      .lastKey     = pTableQueryInfo->lastKey,
+      .w           = pQuery->window,
+      .curWindow   = {.skey = pTableQueryInfo->lastKey, .ekey = pTableQueryInfo->win.ekey},
   };
 
   return info;
@@ -3376,7 +3306,7 @@ static void setEnvBeforeReverseScan(SQueryRuntimeEnv *pRuntimeEnv, SQueryStatusI
 
   STsdbQueryCond cond = {
       .twindow = pQuery->window,
-      .order = pQuery->order.order,
+      .order   = pQuery->order.order,
       .colList = pQuery->colList,
       .numOfCols = pQuery->numOfCols,
   };
@@ -3395,6 +3325,7 @@ static void setEnvBeforeReverseScan(SQueryRuntimeEnv *pRuntimeEnv, SQueryStatusI
 
 static void clearEnvAfterReverseScan(SQueryRuntimeEnv *pRuntimeEnv, SQueryStatusInfo *pStatus) {
   SQuery *pQuery = pRuntimeEnv->pQuery;
+  STableQueryInfo* pTableQueryInfo = pQuery->current;
 
   SWITCH_ORDER(pQuery->order.order);
   switchCtxOrder(pRuntimeEnv);
@@ -3408,17 +3339,19 @@ static void clearEnvAfterReverseScan(SQueryRuntimeEnv *pRuntimeEnv, SQueryStatus
 
   // update the pQuery->window.skey and pQuery->window.ekey to limit the scan scope of sliding query
   // during reverse scan
-  pQuery->lastKey = pStatus->lastKey;
+  pTableQueryInfo->lastKey = pStatus->lastKey;
   pQuery->status = pStatus->status;
-  pQuery->window = pStatus->w;
+  pTableQueryInfo->win = pStatus->w;
 }
 
 void scanAllDataBlocks(SQueryRuntimeEnv *pRuntimeEnv) {
+  SQInfo *pQInfo = (SQInfo *) GET_QINFO_ADDR(pRuntimeEnv);
   SQuery *pQuery = pRuntimeEnv->pQuery;
+  STableQueryInfo *pTableQueryInfo = pQuery->current;
+  
   setQueryStatus(pQuery, QUERY_NOT_COMPLETED);
 
   // store the start query position
-  SQInfo *         pQInfo = (SQInfo *)GET_QINFO_ADDR(pRuntimeEnv);
   SQueryStatusInfo qstatus = getQueryStatusInfo(pRuntimeEnv);
 
   SET_MASTER_SCAN_FLAG(pRuntimeEnv);
@@ -3429,7 +3362,7 @@ void scanAllDataBlocks(SQueryRuntimeEnv *pRuntimeEnv) {
 
     if (pRuntimeEnv->scanFlag == MASTER_SCAN) {
       qstatus.status = pQuery->status;
-      qstatus.curWindow.ekey = pQuery->lastKey - step;
+      qstatus.curWindow.ekey = pTableQueryInfo->lastKey - step;
     }
 
     if (!needScanDataBlocksAgain(pRuntimeEnv)) {
@@ -3443,7 +3376,7 @@ void scanAllDataBlocks(SQueryRuntimeEnv *pRuntimeEnv) {
 
     STsdbQueryCond cond = {
         .twindow = qstatus.curWindow,
-        .order = pQuery->order.order,
+        .order   = pQuery->order.order,
         .colList = pQuery->colList,
         .numOfCols = pQuery->numOfCols,
     };
@@ -3549,12 +3482,10 @@ void destroyTableQueryInfo(STableQueryInfo *pTableQueryInfo, int32_t numOfCols)
 
 void restoreIntervalQueryRange(SQueryRuntimeEnv *pRuntimeEnv, STableQueryInfo *pTableQueryInfo) {
   SQuery *pQuery = pRuntimeEnv->pQuery;
-
-  pQuery->window = pTableQueryInfo->win;
-  pQuery->lastKey = pTableQueryInfo->lastKey;
-
-  assert(((pQuery->lastKey >= pQuery->window.skey) && QUERY_IS_ASC_QUERY(pQuery)) ||
-         ((pQuery->lastKey <= pQuery->window.skey) && !QUERY_IS_ASC_QUERY(pQuery)));
+  pQuery->current = pTableQueryInfo;
+  
+  assert(((pTableQueryInfo->lastKey >= pTableQueryInfo->win.skey) && QUERY_IS_ASC_QUERY(pQuery)) ||
+         ((pTableQueryInfo->lastKey <= pTableQueryInfo->win.skey) && !QUERY_IS_ASC_QUERY(pQuery)));
 }
 
 /**
@@ -3562,8 +3493,10 @@ void restoreIntervalQueryRange(SQueryRuntimeEnv *pRuntimeEnv, STableQueryInfo *p
  * @param pRuntimeEnv
  * @param pDataBlockInfo
  */
-void setExecutionContext(SQInfo *pQInfo, STableQueryInfo *pTableQueryInfo, STableId* pTableId, int32_t groupIdx, TSKEY nextKey) {
+void setExecutionContext(SQInfo *pQInfo, STableId* pTableId, int32_t groupIdx, TSKEY nextKey) {
   SQueryRuntimeEnv *pRuntimeEnv = &pQInfo->runtimeEnv;
+  STableQueryInfo *pTableQueryInfo = pRuntimeEnv->pQuery->current;
+  
   SWindowResInfo *  pWindowResInfo = &pRuntimeEnv->windowResInfo;
   int32_t           GROUPRESULTID = 1;
 
@@ -3647,12 +3580,12 @@ int32_t setAdditionalInfo(SQInfo *pQInfo, STableId* pTableId, STableQueryInfo *p
  *    merged during merge stage. In this case, we need the pTableQueryInfo->lastResRows to decide if there
  *    is a previous result generated or not.
  */
-void setIntervalQueryRange(STableQueryInfo *pTableQueryInfo, SQInfo *pQInfo, TSKEY key) {
+void setIntervalQueryRange(SQInfo *pQInfo, TSKEY key) {
   SQueryRuntimeEnv *pRuntimeEnv = &pQInfo->runtimeEnv;
   SQuery *          pQuery = pRuntimeEnv->pQuery;
-
+  STableQueryInfo *pTableQueryInfo = pQuery->current;
+  
   if (pTableQueryInfo->queryRangeSet) {
-    pQuery->lastKey = key;
     pTableQueryInfo->lastKey = key;
   } else {
     pQuery->window.skey = key;
@@ -3689,8 +3622,6 @@ void setIntervalQueryRange(STableQueryInfo *pTableQueryInfo, SQInfo *pQInfo, TSK
     pTableQueryInfo->queryRangeSet = 1;
     pTableQueryInfo->lastKey = pQuery->window.skey;
     pTableQueryInfo->win.skey = pQuery->window.skey;
-
-    pQuery->lastKey = pQuery->window.skey;
   }
 }
 
@@ -3710,7 +3641,9 @@ bool needPrimaryTimestampCol(SQuery *pQuery, SDataBlockInfo *pDataBlockInfo) {
    * 2. if there are top/bottom, first_dst/last_dst functions, we need to load timestamp column in any cases;
    */
   STimeWindow *w = &pDataBlockInfo->window;
-  bool         loadPrimaryTS = (pQuery->lastKey >= w->skey && pQuery->lastKey <= w->ekey) ||
+  STableQueryInfo* pTableQueryInfo = pQuery->current;
+  
+  bool loadPrimaryTS = (pTableQueryInfo->lastKey >= w->skey && pTableQueryInfo->lastKey <= w->ekey) ||
                        (pQuery->window.ekey >= w->skey && pQuery->window.ekey <= w->ekey) || requireTimestamp(pQuery);
 
   return loadPrimaryTS;
@@ -3847,7 +3780,6 @@ void stableApplyFunctionsOnBlock(SQueryRuntimeEnv *pRuntimeEnv, STableQueryInfo
   }
 
   updateWindowResNumOfRes(pRuntimeEnv, pTableQueryInfo);
-  updatelastkey(pQuery, pTableQueryInfo);
 }
 
 bool vnodeHasRemainResults(void *handle) {
@@ -4041,10 +3973,12 @@ void vnodePrintQueryStatistics(SQInfo *pQInfo) {
 
 static void updateOffsetVal(SQueryRuntimeEnv *pRuntimeEnv, SDataBlockInfo *pBlockInfo) {
   SQuery *pQuery = pRuntimeEnv->pQuery;
+  STableQueryInfo* pTableQueryInfo = pQuery->current;
+  
   int32_t step = GET_FORWARD_DIRECTION_FACTOR(pQuery->order.order);
 
   if (pQuery->limit.offset == pBlockInfo->rows) {  // current block will ignore completed
-    pQuery->lastKey = QUERY_IS_ASC_QUERY(pQuery) ? pBlockInfo->window.ekey + step : pBlockInfo->window.skey + step;
+    pTableQueryInfo->lastKey = QUERY_IS_ASC_QUERY(pQuery) ? pBlockInfo->window.ekey + step : pBlockInfo->window.skey + step;
     pQuery->limit.offset = 0;
     return;
   }
@@ -4064,11 +3998,10 @@ static void updateOffsetVal(SQueryRuntimeEnv *pRuntimeEnv, SDataBlockInfo *pBloc
   TSKEY *keys = (TSKEY *)pColInfoData->pData;
 
   // update the offset value
-  pQuery->lastKey = keys[pQuery->pos];
+  pTableQueryInfo->lastKey = keys[pQuery->pos];
   pQuery->limit.offset = 0;
 
-  int32_t numOfRes = tableApplyFunctionsOnBlock(pRuntimeEnv, pBlockInfo, NULL, binarySearchForKey,
-                                                &pRuntimeEnv->windowResInfo, pDataBlock);
+  int32_t numOfRes = tableApplyFunctionsOnBlock(pRuntimeEnv, pBlockInfo, NULL, binarySearchForKey, pDataBlock);
 
   qTrace("QInfo:%p check data block, brange:%" PRId64 "-%" PRId64 ", rows:%d, res:%d", GET_QINFO_ADDR(pRuntimeEnv),
          pBlockInfo->window.skey, pBlockInfo->window.ekey, pBlockInfo->rows, numOfRes);
@@ -4084,6 +4017,7 @@ void skipBlocks(SQueryRuntimeEnv *pRuntimeEnv) {
   pQuery->pos = 0;
   int32_t step = GET_FORWARD_DIRECTION_FACTOR(pQuery->order.order);
 
+  STableQueryInfo* pTableQueryInfo = pQuery->current;
   TsdbQueryHandleT pQueryHandle = pRuntimeEnv->pQueryHandle;
 
   while (tsdbNextDataBlock(pQueryHandle)) {
@@ -4095,8 +4029,8 @@ void skipBlocks(SQueryRuntimeEnv *pRuntimeEnv) {
 
     if (pQuery->limit.offset > blockInfo.rows) {
       pQuery->limit.offset -= blockInfo.rows;
-      pQuery->lastKey = (QUERY_IS_ASC_QUERY(pQuery)) ? blockInfo.window.ekey : blockInfo.window.skey;
-      pQuery->lastKey += step;
+      pTableQueryInfo->lastKey = (QUERY_IS_ASC_QUERY(pQuery)) ? blockInfo.window.ekey : blockInfo.window.skey;
+      pTableQueryInfo->lastKey += step;
 
       qTrace("QInfo:%p skip rows:%d, offset:%" PRId64 "", GET_QINFO_ADDR(pRuntimeEnv), blockInfo.rows,
              pQuery->limit.offset);
@@ -4125,6 +4059,7 @@ static bool skipTimeInterval(SQueryRuntimeEnv *pRuntimeEnv) {
   TSKEY           skey1, ekey1;
   STimeWindow     w = {0};
   SWindowResInfo *pWindowResInfo = &pRuntimeEnv->windowResInfo;
+  STableQueryInfo *pTableQueryInfo = pQuery->current;
 
   while (tsdbNextDataBlock(pRuntimeEnv->pQueryHandle)) {
     SDataBlockInfo blockInfo = tsdbRetrieveDataBlockInfo(pRuntimeEnv->pQueryHandle);
@@ -4170,11 +4105,10 @@ static bool skipTimeInterval(SQueryRuntimeEnv *pRuntimeEnv) {
 
           // set the abort info
           pQuery->pos = startPos;
-          pQuery->lastKey = ((TSKEY *)pColInfoData->pData)[startPos];
+          pTableQueryInfo->lastKey = ((TSKEY *)pColInfoData->pData)[startPos];
           pWindowResInfo->prevSKey = tw.skey;
 
-          int32_t numOfRes = tableApplyFunctionsOnBlock(pRuntimeEnv, &blockInfo, NULL, binarySearchForKey,
-                                                        &pRuntimeEnv->windowResInfo, pDataBlock);
+          int32_t numOfRes = tableApplyFunctionsOnBlock(pRuntimeEnv, &blockInfo, NULL, binarySearchForKey, pDataBlock);
 
           qTrace("QInfo:%p check data block, brange:%" PRId64 "-%" PRId64 ", rows:%d, res:%d",
                  GET_QINFO_ADDR(pRuntimeEnv), blockInfo.window.skey, blockInfo.window.ekey, blockInfo.rows, numOfRes);
@@ -4199,7 +4133,7 @@ static bool skipTimeInterval(SQueryRuntimeEnv *pRuntimeEnv) {
 
         // set the abort info
         pQuery->pos = startPos;
-        pQuery->lastKey = ((TSKEY *)pColInfoData->pData)[startPos];
+        pTableQueryInfo->lastKey = ((TSKEY *)pColInfoData->pData)[startPos];
         pWindowResInfo->prevSKey = tw.skey;
         win = tw;
       } else {
@@ -4220,12 +4154,9 @@ int32_t doInitQInfo(SQInfo *pQInfo, void *param, void *tsdb, int32_t vgId, bool
   setScanLimitationByResultBuffer(pQuery);
   changeExecuteScanOrder(pQuery, false);
 
-  // dataInCache requires lastKey value
-  pQuery->lastKey = pQuery->window.skey;
-
   STsdbQueryCond cond = {
       .twindow = pQuery->window,
-      .order = pQuery->order.order,
+      .order   = pQuery->order.order,
       .colList = pQuery->colList,
       .numOfCols = pQuery->numOfCols,
   };
@@ -4238,6 +4169,9 @@ int32_t doInitQInfo(SQInfo *pQInfo, void *param, void *tsdb, int32_t vgId, bool
     } else if (!isSTableQuery || isIntervalQuery(pQuery) || isFixedOutputQuery(pQuery)) {
       pRuntimeEnv->pQueryHandle = tsdbQueryTables(tsdb, &cond, &pQInfo->tableIdGroupInfo);
     }
+  
+    // create the table query support structures
+    createTableQueryInfo(pQInfo);
   }
   
   pQInfo->tsdb = tsdb;
@@ -4331,7 +4265,6 @@ int32_t doInitQInfo(SQInfo *pQInfo, void *param, void *tsdb, int32_t vgId, bool
 //  }
 
   // the pQuery->window.skey is changed during normalizedFirstQueryRange, so set the newest lastkey value
-  pQuery->lastKey = pQuery->window.skey;
   return TSDB_CODE_SUCCESS;
 }
 
@@ -4399,18 +4332,19 @@ static int64_t queryOnDataBlocks(SQInfo *pQInfo) {
         break;
       }
     }
-
+  
     assert(pTableQueryInfo != NULL);
     restoreIntervalQueryRange(pRuntimeEnv, pTableQueryInfo);
 
     SDataStatis *pStatis = NULL;
-    SArray *     pDataBlock = loadDataBlockOnDemand(pRuntimeEnv, &blockInfo, &pStatis);
+    
+    SArray *pDataBlock = loadDataBlockOnDemand(pRuntimeEnv, pQueryHandle, &blockInfo, &pStatis);
 
     TSKEY nextKey = blockInfo.window.skey;
     if (!isIntervalQuery(pQuery)) {
-      setExecutionContext(pQInfo, pTableQueryInfo, &pTableQueryInfo->id, pTableQueryInfo->groupIdx, nextKey);
+      setExecutionContext(pQInfo, &pTableQueryInfo->id, pTableQueryInfo->groupIdx, nextKey);
     } else {  // interval query
-      setIntervalQueryRange(pTableQueryInfo, pQInfo, nextKey);
+      setIntervalQueryRange(pQInfo, nextKey);
       int32_t ret = setAdditionalInfo(pQInfo, &pTableQueryInfo->id, pTableQueryInfo);
 
       if (ret != TSDB_CODE_SUCCESS) {
@@ -4446,6 +4380,7 @@ static bool multiTableMultioutputHelper(SQInfo *pQInfo, int32_t index) {
       .numOfCols = pQuery->numOfCols,
   };
 
+  // todo refactor
   SArray *g1 = taosArrayInit(1, POINTER_BYTES);
   SArray *tx = taosArrayInit(1, sizeof(STableId));
 
@@ -4564,6 +4499,9 @@ static void sequentialTableProcess(SQInfo *pQInfo) {
         
         initCtxOutputBuf(pRuntimeEnv);
         setTagVal(pRuntimeEnv, (STableId*) taosArrayGet(tx, 0), pQInfo->tsdb);
+        
+        // here we simply set the first table as current table
+        pRuntimeEnv->pQuery->current = ((SGroupItem*) taosArrayGet(group, 0))->info;
         scanAllDataBlocks(pRuntimeEnv);
         
         int64_t numOfRes = getNumOfResult(pRuntimeEnv);
@@ -4580,8 +4518,6 @@ static void sequentialTableProcess(SQInfo *pQInfo) {
       }
     }
   } else {
-    createTableQueryInfo(pQInfo);
-
     /*
      * 1. super table projection query, 2. group-by on normal columns query, 3. ts-comp query
      * if the subgroup index is larger than 0, results generated by group by tbname,k is existed.
@@ -4614,12 +4550,8 @@ static void sequentialTableProcess(SQInfo *pQInfo) {
       }
 
       SGroupItem *item = taosArrayGet(group, pQInfo->tableIndex);
+      pQuery->current = item->info;
       
-      STableQueryInfo *pInfo = item->info;
-      if (pInfo->lastKey > 0) {
-        pQuery->window.skey = pInfo->lastKey;
-      }
-
       if (!multiTableMultioutputHelper(pQInfo, pQInfo->tableIndex)) {
         pQInfo->tableIndex++;
         continue;
@@ -4627,7 +4559,7 @@ static void sequentialTableProcess(SQInfo *pQInfo) {
 
       //      SPointInterpoSupporter pointInterpSupporter = {0};
 
-      // TODO handle the limit problem
+      // TODO handle the limit offset problem
       if (pQuery->numOfFilterCols == 0 && pQuery->limit.offset > 0) {
         //        skipBlocks(pRuntimeEnv);
 
@@ -4659,8 +4591,6 @@ static void sequentialTableProcess(SQInfo *pQInfo) {
          * to ensure that, we can reset the query range once query on a meter is completed.
          */
         pQInfo->tableIndex++;
-        pInfo->lastKey = pQuery->lastKey;
-
         // if the buffer is full or group by each table, we need to jump out of the loop
         if (Q_STATUS_EQUAL(pQuery->status, QUERY_RESBUF_FULL) /*||
             isGroupbyEachTable(pQuery->pGroupbyExpr, pSupporter->pSidSet)*/) {
@@ -4668,7 +4598,7 @@ static void sequentialTableProcess(SQInfo *pQInfo) {
         }
 
       } else {  // forward query range
-        pQuery->window.skey = pQuery->lastKey;
+        pQuery->window.skey = pQuery->current->lastKey;
 
         // all data in the result buffer are skipped due to the offset, continue to retrieve data from current meter
         if (pQuery->rec.rows == 0) {
@@ -4853,12 +4783,9 @@ static void multiTableQueryProcess(SQInfo *pQInfo) {
   qTrace("QInfo:%p query start, qrange:%" PRId64 "-%" PRId64 ", order:%d, forward scan start", pQInfo,
          pQuery->window.skey, pQuery->window.ekey, pQuery->order.order);
 
-  // create the query support structures
-  createTableQueryInfo(pQInfo);
-
   // do check all qualified data blocks
   int64_t el = queryOnDataBlocks(pQInfo);
-  qTrace("QInfo:%p forward scan completed, elapsed time: %lldms, reversed scan start", pQInfo, el);
+  qTrace("QInfo:%p master scan completed, elapsed time: %lldms, reverse scan start", pQInfo, el);
 
   // query error occurred or query is killed, abort current execution
   if (pQInfo->code != TSDB_CODE_SUCCESS || isQueryKilled(pQInfo)) {
@@ -4909,10 +4836,12 @@ static void multiTableQueryProcess(SQInfo *pQInfo) {
  * select count(*)/top(field,k)/avg(field name) from table_name [where ts>now-1a];
  * select count(*) from table_name group by status_column;
  */
-static void tableFixedOutputProcess(SQInfo *pQInfo) {
+static void tableFixedOutputProcess(SQInfo *pQInfo, STableQueryInfo* pTableInfo) {
   SQueryRuntimeEnv *pRuntimeEnv = &pQInfo->runtimeEnv;
-  SQuery *          pQuery = pRuntimeEnv->pQuery;
-
+  
+  SQuery *pQuery = pRuntimeEnv->pQuery;
+  pQuery->current = pTableInfo;  // set current query table info
+  
   scanAllDataBlocks(pRuntimeEnv);
   finalizeQueryResult(pRuntimeEnv);
 
@@ -4932,10 +4861,12 @@ static void tableFixedOutputProcess(SQInfo *pQInfo) {
   limitResults(pQInfo);
 }
 
-static void tableMultiOutputProcess(SQInfo *pQInfo) {
+static void tableMultiOutputProcess(SQInfo *pQInfo, STableQueryInfo* pTableInfo) {
   SQueryRuntimeEnv *pRuntimeEnv = &pQInfo->runtimeEnv;
-  SQuery *          pQuery = pRuntimeEnv->pQuery;
-
+  
+  SQuery *pQuery = pRuntimeEnv->pQuery;
+  pQuery->current = pTableInfo;
+  
   // for ts_comp query, re-initialized is not allowed
   if (!isTSCompQuery(pQuery)) {
     resetCtxOutputBuf(pRuntimeEnv);
@@ -4970,15 +4901,15 @@ static void tableMultiOutputProcess(SQInfo *pQInfo) {
     }
 
     qTrace("QInfo:%p vid:%d sid:%d id:%s, skip current result, offset:%" PRId64 ", next qrange:%" PRId64 "-%" PRId64,
-           pQInfo, pQuery->limit.offset, pQuery->lastKey);
+           pQInfo, pQuery->limit.offset, pQuery->current->lastKey);
 
     resetCtxOutputBuf(pRuntimeEnv);
   }
 
   limitResults(pQInfo);
   if (Q_STATUS_EQUAL(pQuery->status, QUERY_RESBUF_FULL)) {
-    qTrace("QInfo:%p query paused due to output limitation, next qrange:%" PRId64 "-%" PRId64, pQInfo, pQuery->lastKey,
-           pQuery->window.ekey);
+    qTrace("QInfo:%p query paused due to output limitation, next qrange:%" PRId64 "-%" PRId64, pQInfo,
+        pQuery->current->lastKey, pQuery->window.ekey);
   }
 
   if (!isTSCompQuery(pQuery)) {
@@ -5018,11 +4949,12 @@ static void tableIntervalProcessImpl(SQueryRuntimeEnv *pRuntimeEnv) {
 }
 
 // handle time interval query on table
-static void tableIntervalProcess(SQInfo *pQInfo) {
+static void tableIntervalProcess(SQInfo *pQInfo, STableQueryInfo* pTableInfo) {
   SQueryRuntimeEnv *pRuntimeEnv = &(pQInfo->runtimeEnv);
-  SQuery *          pQuery = pRuntimeEnv->pQuery;
 
   int32_t numOfInterpo = 0;
+  SQuery *pQuery = pRuntimeEnv->pQuery;
+  pQuery->current = pTableInfo;
 
   // skip blocks without load the actual data block from file if no filter condition present
   skipTimeInterval(pRuntimeEnv);
@@ -5131,15 +5063,19 @@ static void tableQueryImpl(SQInfo *pQInfo) {
   // number of points returned during this query
   pQuery->rec.rows = 0;
   int64_t st = taosGetTimestampUs();
-
+  
+  assert(pQInfo->groupInfo.numOfTables == 1);
+  SArray* g = taosArrayGetP(pQInfo->groupInfo.pGroupList, 0);
+  SGroupItem* item = taosArrayGet(g, 0);
+  
   // group by normal column, sliding window query, interval query are handled by interval query processor
   if (isIntervalQuery(pQuery) || isGroupbyNormalCol(pQuery->pGroupbyExpr)) {  // interval (down sampling operation)
-    tableIntervalProcess(pQInfo);
+    tableIntervalProcess(pQInfo, item->info);
   } else if (isFixedOutputQuery(pQuery)) {
-    tableFixedOutputProcess(pQInfo);
+    tableFixedOutputProcess(pQInfo, item->info);
   } else {  // diff/add/multiply/subtract/division
     assert(pQuery->checkBuffer == 1);
-    tableMultiOutputProcess(pQInfo);
+    tableMultiOutputProcess(pQInfo, item->info);
   }
 
   // record the total elapsed time
@@ -5833,7 +5769,6 @@ static SQInfo *createQInfoImpl(SQueryTableMsg *pQueryMsg, SSqlGroupbyExpr *pGrou
   pQuery->pos = -1;
 
   pQuery->window = pQueryMsg->window;
-  pQuery->lastKey = pQuery->window.skey;
 
   if (sem_init(&pQInfo->dataReady, 0, 0) != 0) {
     qError("QInfo:%p init dataReady sem failed, reason:%s", pQInfo, strerror(errno));
@@ -5910,9 +5845,7 @@ static int32_t initQInfo(SQueryTableMsg *pQueryMsg, void *tsdb, int32_t vgId, SQ
   if ((code = doInitQInfo(pQInfo, pTSBuf, tsdb, vgId, isSTable)) != TSDB_CODE_SUCCESS) {
     goto _error;
   }
-
-  // qTrace("QInfo:%p set query flag and prepare runtime environment completed, ref:%d, wait for schedule", pQInfo,
-  //       pQInfo->refCount);
+  
   return code;
 
 _error:
@@ -6085,34 +6018,35 @@ int32_t qCreateQueryInfo(void *tsdb, int32_t vgId, SQueryTableMsg *pQueryMsg, qi
   if (pQueryMsg->numOfTables <= 0) {
     qError("Invalid number of tables to query, numOfTables:%d", pQueryMsg->numOfTables);
     code = TSDB_CODE_INVALID_QUERY_MSG;
-    goto _query_over;
+    goto _over;
   }
 
   if (pTableIdList == NULL || taosArrayGetSize(pTableIdList) == 0) {
     qError("qmsg:%p, SQueryTableMsg wrong format", pQueryMsg);
     code = TSDB_CODE_INVALID_QUERY_MSG;
-    goto _query_over;
+    goto _over;
   }
 
   SExprInfo *pExprs = NULL;
   if ((code = createSqlFunctionExprFromMsg(pQueryMsg, &pExprs, pExprMsg, pTagColumnInfo)) != TSDB_CODE_SUCCESS) {
-    goto _query_over;
+    goto _over;
   }
 
   SSqlGroupbyExpr *pGroupbyExpr = createGroupbyExprFromMsg(pQueryMsg, pGroupColIndex, &code);
   if ((pGroupbyExpr == NULL && pQueryMsg->numOfGroupCols != 0) || code != TSDB_CODE_SUCCESS) {
-    goto _query_over;
+    goto _over;
   }
 
   bool isSTableQuery = false;
   STableGroupInfo groupInfo = {0};
   
+  //todo multitable_query??
   if (TSDB_QUERY_HAS_TYPE(pQueryMsg->queryType, TSDB_QUERY_TYPE_MULTITABLE_QUERY|TSDB_QUERY_TYPE_TABLE_QUERY)) {
     isSTableQuery = TSDB_QUERY_HAS_TYPE(pQueryMsg->queryType, TSDB_QUERY_TYPE_MULTITABLE_QUERY);
     
     STableId *id = taosArrayGet(pTableIdList, 0);
     if ((code = tsdbGetOneTableGroup(tsdb, id->uid, &groupInfo)) != TSDB_CODE_SUCCESS) {
-      goto _query_over;
+      goto _over;
     }
   } else if (TSDB_QUERY_HAS_TYPE(pQueryMsg->queryType, TSDB_QUERY_TYPE_STABLE_QUERY)) {
     isSTableQuery = true;
@@ -6129,7 +6063,7 @@ int32_t qCreateQueryInfo(void *tsdb, int32_t vgId, SQueryTableMsg *pQueryMsg, qi
                                          numOfGroupByCols);
     if (groupInfo.numOfTables == 0) {  // no qualified tables no need to do query
       code = TSDB_CODE_SUCCESS;
-      goto _query_over;
+      goto _over;
     }
   } else {
     assert(0);
@@ -6138,11 +6072,12 @@ int32_t qCreateQueryInfo(void *tsdb, int32_t vgId, SQueryTableMsg *pQueryMsg, qi
   (*pQInfo) = createQInfoImpl(pQueryMsg, pGroupbyExpr, pExprs, &groupInfo, pTagColumnInfo);
   if ((*pQInfo) == NULL) {
     code = TSDB_CODE_SERV_OUT_OF_MEMORY;
+    goto _over;
   }
 
   code = initQInfo(pQueryMsg, tsdb, vgId, *pQInfo, isSTableQuery);
 
-_query_over:
+_over:
   tfree(tagCond);
   tfree(tbnameCond);
   taosArrayDestroy(pTableIdList);
@@ -6318,12 +6253,10 @@ static void buildTagQueryResult(SQInfo* pQInfo) {
       for(int32_t j = 0; j < pQuery->numOfOutput; ++j) {
         // todo check the return value, refactor codes
         if (pExprInfo[j].base.colInfo.colId == TSDB_TBNAME_COLUMN_INDEX) {
-          tsdbGetTableName(pQInfo->tsdb, &item->id, &data);
+          data = tsdbGetTableName(pQInfo->tsdb, &item->id, &bytes);
           
           char* dst = pQuery->sdata[j]->data + i * (TSDB_TABLE_NAME_LEN + VARSTR_HEADER_SIZE);
-          STR_WITH_MAXSIZE_TO_VARSTR(dst, data, TSDB_TABLE_NAME_LEN);
-          tfree(data);
-        
+          memcpy(dst, data, varDataTLen(data));
         } else {// todo refactor, return the true length of binary|nchar data
           tsdbGetTableTagVal(pQInfo->tsdb, &item->id, pExprInfo[j].base.colInfo.colId, &type, &bytes, &data);
           assert(bytes == pExprInfo[j].bytes && type == pExprInfo[j].type);
diff --git a/src/tsdb/inc/tsdbMain.h b/src/tsdb/inc/tsdbMain.h
index 278463f0d2acfadd4a9794a87f3e2f6cc23b9a41..2c3aff4b84bf5ad3d8efff1358e6192eae610575 100644
--- a/src/tsdb/inc/tsdbMain.h
+++ b/src/tsdb/inc/tsdbMain.h
@@ -81,7 +81,6 @@ typedef struct {
 // ---------- TSDB TABLE DEFINITION
 typedef struct STable {
   int8_t         type;
-  char *         name;
   STableId       tableId;
   int64_t        superUid;  // Super table UID
   int32_t        sversion;
@@ -96,9 +95,10 @@ typedef struct STable {
   TSKEY          lastKey;        // lastkey inserted in this table, initialized as 0, TODO: make a structure
   struct STable *next;           // TODO: remove the next
   struct STable *prev;
+  tstr *         name;           // NOTE: there a flexible string here
 } STable;
 
-#define TSDB_GET_TABLE_LAST_KEY(pTable) ((pTable)->lastKey)
+#define TSDB_GET_TABLE_LAST_KEY(tb) ((tb)->lastKey)
 
 void *  tsdbEncodeTable(STable *pTable, int *contLen);
 STable *tsdbDecodeTable(void *cont, int contLen);
@@ -121,6 +121,12 @@ typedef struct {
   int        maxCols;
 } STsdbMeta;
 
+// element put in skiplist for each table
+typedef struct STableIndexElem {
+  STsdbMeta* pMeta;
+  STable*    pTable;
+} STableIndexElem;
+
 STsdbMeta *tsdbInitMeta(char *rootDir, int32_t maxTables);
 int32_t    tsdbFreeMeta(STsdbMeta *pMeta);
 STSchema * tsdbGetTableSchema(STsdbMeta *pMeta, STable *pTable);
@@ -150,7 +156,7 @@ int32_t tsdbDropTableImpl(STsdbMeta *pMeta, STableId tableId);
 STable *tsdbIsValidTableToInsert(STsdbMeta *pMeta, STableId tableId);
 // int32_t tsdbInsertRowToTableImpl(SSkipListNode *pNode, STable *pTable);
 STable *tsdbGetTableByUid(STsdbMeta *pMeta, int64_t uid);
-char *  getTupleKey(const void *data);
+char *getTSTupleKey(const void * data);
 
 typedef struct {
   int  blockId;
diff --git a/src/tsdb/src/tsdbMain.c b/src/tsdb/src/tsdbMain.c
index 8d570911a91bd2fd3c730dd04617e65af3558130..653ec50af8b4ef66e804ca3f617e1302119afe41 100644
--- a/src/tsdb/src/tsdbMain.c
+++ b/src/tsdb/src/tsdbMain.c
@@ -808,7 +808,7 @@ static int32_t tdInsertRowToTable(STsdbRepo *pRepo, SDataRow row, STable *pTable
   if (pTable->mem == NULL) {
     pTable->mem = (SMemTable *)calloc(1, sizeof(SMemTable));
     if (pTable->mem == NULL) return -1;
-    pTable->mem->pData = tSkipListCreate(5, TSDB_DATA_TYPE_TIMESTAMP, TYPE_BYTES[TSDB_DATA_TYPE_TIMESTAMP], 0, 0, 0, getTupleKey);
+    pTable->mem->pData = tSkipListCreate(5, TSDB_DATA_TYPE_TIMESTAMP, TYPE_BYTES[TSDB_DATA_TYPE_TIMESTAMP], 0, 0, 0, getTSTupleKey);
     pTable->mem->keyFirst = INT64_MAX;
     pTable->mem->keyLast = 0;
   }
@@ -831,7 +831,7 @@ static int32_t tdInsertRowToTable(STsdbRepo *pRepo, SDataRow row, STable *pTable
   if (pTable->mem == NULL) {
     pTable->mem = (SMemTable *)calloc(1, sizeof(SMemTable));
     if (pTable->mem == NULL) return -1;
-    pTable->mem->pData = tSkipListCreate(5, TSDB_DATA_TYPE_TIMESTAMP, TYPE_BYTES[TSDB_DATA_TYPE_TIMESTAMP], 0, 0, 0, getTupleKey);
+    pTable->mem->pData = tSkipListCreate(5, TSDB_DATA_TYPE_TIMESTAMP, TYPE_BYTES[TSDB_DATA_TYPE_TIMESTAMP], 0, 0, 0, getTSTupleKey);
     pTable->mem->keyFirst = INT64_MAX;
     pTable->mem->keyLast = 0;
   }
diff --git a/src/tsdb/src/tsdbMeta.c b/src/tsdb/src/tsdbMeta.c
index 0828db7f00d2e869abf2aef3fe02c926ff77be4f..107da929655e355dbc7e42697a0a7773433b23e6 100644
--- a/src/tsdb/src/tsdbMeta.c
+++ b/src/tsdb/src/tsdbMeta.c
@@ -1,6 +1,4 @@
 #include <stdlib.h>
-
-// #include "taosdef.h"
 #include "tskiplist.h"
 #include "tsdb.h"
 #include "taosdef.h"
@@ -10,6 +8,8 @@
 #define TSDB_SUPER_TABLE_SL_LEVEL 5 // TODO: may change here
 #define TSDB_META_FILE_NAME "META"
 
+const int32_t DEFAULT_TAG_INDEX_COLUMN = 0;
+
 static int     tsdbFreeTable(STable *pTable);
 static int32_t tsdbCheckTableCfg(STableCfg *pCfg);
 static int     tsdbAddTableToMeta(STsdbMeta *pMeta, STable *pTable, bool addIdx);
@@ -39,11 +39,12 @@ void *tsdbEncodeTable(STable *pTable, int *contLen) {
 
   void *ptr = ret;
   T_APPEND_MEMBER(ptr, pTable, STable, type);
-  // Encode name
-  *(int *)ptr = strlen(pTable->name);
+  // Encode name, todo refactor
+  *(int *)ptr = varDataLen(pTable->name);
   ptr = (char *)ptr + sizeof(int);
-  memcpy(ptr, pTable->name, strlen(pTable->name));
-  ptr = (char *)ptr + strlen(pTable->name);
+  memcpy(ptr, varDataVal(pTable->name), varDataLen(pTable->name));
+  ptr = (char *)ptr + varDataLen(pTable->name);
+  
   T_APPEND_MEMBER(ptr, &(pTable->tableId), STableId, uid);
   T_APPEND_MEMBER(ptr, &(pTable->tableId), STableId, tid);
   T_APPEND_MEMBER(ptr, pTable, STable, superUid);
@@ -79,9 +80,12 @@ STable *tsdbDecodeTable(void *cont, int contLen) {
   T_READ_MEMBER(ptr, int8_t, pTable->type);
   int len = *(int *)ptr;
   ptr = (char *)ptr + sizeof(int);
-  pTable->name = calloc(1, len + 1);
+  pTable->name = calloc(1, len + VARSTR_HEADER_SIZE);
   if (pTable->name == NULL) return NULL;
-  memcpy(pTable->name, ptr, len);
+  
+  varDataSetLen(pTable->name, len);
+  memcpy(pTable->name->data, ptr, len);
+  
   ptr = (char *)ptr + len;
   T_READ_MEMBER(ptr, int64_t, pTable->tableId.uid);
   T_READ_MEMBER(ptr, int32_t, pTable->tableId.tid);
@@ -105,8 +109,13 @@ void tsdbFreeEncode(void *cont) {
 }
 
 static char* getTagIndexKey(const void* pData) {
-  STable* table = *(STable**) pData;
-  return getTupleKey(table->tagVal);
+  STableIndexElem* elem = (STableIndexElem*) pData;
+  
+  SDataRow row = elem->pTable->tagVal;
+  STSchema* pSchema = tsdbGetTableTagSchema(elem->pMeta, elem->pTable);
+  STColumn* pCol = &pSchema->columns[DEFAULT_TAG_INDEX_COLUMN];
+  
+  return tdGetRowDataOfCol(row, pCol->type, TD_DATA_ROW_HEAD_SIZE + pCol->offset);
 }
 
 int tsdbRestoreTable(void *pHandle, void *cont, int contLen) {
@@ -225,36 +234,28 @@ STSchema * tsdbGetTableTagSchema(STsdbMeta *pMeta, STable *pTable) {
   }
 }
 
+// todo refactor table name definition
 int32_t tsdbGetTableTagVal(TsdbRepoT* repo, STableId* id, int32_t colId, int16_t* type, int16_t* bytes, char** val) {
   STsdbMeta* pMeta = tsdbGetMeta(repo);
   STable* pTable = tsdbGetTableByUid(pMeta, id->uid);
   
   STSchema* pSchema = tsdbGetTableTagSchema(pMeta, pTable);
-  
   STColumn* pCol = NULL;
-  int32_t offset = 0;
+  
   for(int32_t col = 0; col < schemaNCols(pSchema); ++col) {
     STColumn* p = schemaColAt(pSchema, col);
     if (p->colId == colId) {
       pCol = p;
       break;
     }
-  
-    if (p->type == TSDB_DATA_TYPE_BINARY || p->type == TSDB_DATA_TYPE_NCHAR) {
-      offset += sizeof(int32_t);
-    } else {
-      offset += p->bytes;
-    }
   }
   
   if (pCol == NULL) {
     return -1;  // No matched tags. Maybe the modification of tags has not been done yet.
   }
   
-  assert(pCol != NULL);
-  
   SDataRow row = (SDataRow)pTable->tagVal;
-  char* d = tdGetRowDataOfCol(row, pCol->type, TD_DATA_ROW_HEAD_SIZE + offset);
+  char* d = tdGetRowDataOfCol(row, pCol->type, TD_DATA_ROW_HEAD_SIZE + pCol->offset);
   
   *val = d;
   *type  = pCol->type;
@@ -263,15 +264,22 @@ int32_t tsdbGetTableTagVal(TsdbRepoT* repo, STableId* id, int32_t colId, int16_t
   return TSDB_CODE_SUCCESS;
 }
 
-int32_t tsdbGetTableName(TsdbRepoT *repo, STableId* id, char** name) {
+char* tsdbGetTableName(TsdbRepoT *repo, const STableId* id, int16_t* bytes) {
   STsdbMeta* pMeta = tsdbGetMeta(repo);
   STable* pTable = tsdbGetTableByUid(pMeta, id->uid);
   
-  *name = strndup(pTable->name, TSDB_TABLE_NAME_LEN);
-  if (*name == NULL) {
-    return -1;
+  if (pTable == NULL) {
+    if (bytes != NULL) {
+      *bytes = 0;
+    }
+    
+    return NULL;
   } else {
-    return 0;
+    if (bytes != NULL) {
+      *bytes = varDataLen(pTable->name);
+    }
+    
+    return (char*) pTable->name;
   }
 }
 
@@ -296,7 +304,11 @@ int32_t tsdbCreateTableImpl(STsdbMeta *pMeta, STableCfg *pCfg) {
       super->schema = tdDupSchema(pCfg->schema);
       super->tagSchema = tdDupSchema(pCfg->tagSchema);
       super->tagVal = NULL;
-      super->name = strdup(pCfg->sname);
+      
+      // todo refactor extract method
+      size_t size = strnlen(pCfg->sname, TSDB_TABLE_NAME_LEN);
+      super->name = malloc(size + VARSTR_HEADER_SIZE);
+      STR_WITH_SIZE_TO_VARSTR(super->name, pCfg->sname, size);
 
       // index the first tag column
       STColumn* pColSchema = schemaColAt(super->tagSchema, 0);
@@ -322,7 +334,11 @@ int32_t tsdbCreateTableImpl(STsdbMeta *pMeta, STableCfg *pCfg) {
   }
 
   table->tableId = pCfg->tableId;
-  table->name = strdup(pCfg->name);
+  
+  size_t size = strnlen(pCfg->name, TSDB_TABLE_NAME_LEN);
+  table->name = malloc(size + VARSTR_HEADER_SIZE);
+  STR_WITH_SIZE_TO_VARSTR(table->name, pCfg->name, size);
+  
   table->lastKey = 0;
   if (IS_CREATE_STABLE(pCfg)) { // TSDB_CHILD_TABLE
     table->type = TSDB_CHILD_TABLE;
@@ -513,11 +529,14 @@ static int tsdbAddTableIntoIndex(STsdbMeta *pMeta, STable *pTable) {
   
   // NOTE: do not allocate the space for key, since in each skip list node, only keep the pointer to pTable, not the
   // actual key value, and the key value will be retrieved during query through the pTable and getTagIndexKey function
-  SSkipListNode* pNode = calloc(1, headSize + POINTER_BYTES);
+  SSkipListNode* pNode = calloc(1, headSize + sizeof(STableIndexElem));
   pNode->level = level;
   
   SSkipList* list = pSTable->pIndex;
-  memcpy(SL_GET_NODE_DATA(pNode), &pTable, POINTER_BYTES);
+  STableIndexElem* elem = (STableIndexElem*) (SL_GET_NODE_DATA(pNode));
+  
+  elem->pTable = pTable;
+  elem->pMeta = pMeta;
   
   tSkipListPut(list, pNode);
   return 0;
@@ -539,7 +558,7 @@ static int tsdbRemoveTableFromIndex(STsdbMeta *pMeta, STable *pTable) {
 static int tsdbEstimateTableEncodeSize(STable *pTable) {
   int size = 0;
   size += T_MEMBER_SIZE(STable, type);
-  size += sizeof(int) + strlen(pTable->name);
+  size += sizeof(int) + varDataLen(pTable->name);
   size += T_MEMBER_SIZE(STable, tableId);
   size += T_MEMBER_SIZE(STable, superUid);
   size += T_MEMBER_SIZE(STable, sversion);
@@ -556,8 +575,7 @@ static int tsdbEstimateTableEncodeSize(STable *pTable) {
   return size;
 }
 
-char *getTupleKey(const void * data) {
+char *getTSTupleKey(const void * data) {
   SDataRow row = (SDataRow)data;
-
   return POINTER_SHIFT(row, TD_DATA_ROW_HEAD_SIZE);
 }
\ No newline at end of file
diff --git a/src/tsdb/src/tsdbRead.c b/src/tsdb/src/tsdbRead.c
index 008ad223ed718de420bcb770b6dec4d736afb6e4..cbb128045eb849d00b9b9b03ea0c9d04abd37de7 100644
--- a/src/tsdb/src/tsdbRead.c
+++ b/src/tsdb/src/tsdbRead.c
@@ -1076,17 +1076,13 @@ static int tsdbReadRowsFromCache(SSkipListIterator* pIter, STable* pTable, TSKEY
       }
       
       assert(offset != -1); // todo handle error
+      void *value = tdGetRowDataOfCol(row, pColInfo->info.type, TD_DATA_ROW_HEAD_SIZE + offset);
       
       if (pColInfo->info.type == TSDB_DATA_TYPE_BINARY || pColInfo->info.type == TSDB_DATA_TYPE_NCHAR) {
-        void *value = tdGetRowDataOfCol(row, pColInfo->info.type, TD_DATA_ROW_HEAD_SIZE + offset);
         memcpy(pData, value, varDataTLen(value));
-  
-        offset += sizeof(int32_t);
       } else {
-        memcpy(pData, dataRowTuple(row) + offset, pColInfo->info.bytes);
-        offset += pColInfo->info.bytes;
+        memcpy(pData, value, pColInfo->info.bytes);
       }
-      
     }
 
     numOfRows++;
@@ -1225,8 +1221,8 @@ static int32_t getAllTableIdList(STable* pSuperTable, SArray* list) {
   while (tSkipListIterNext(iter)) {
     SSkipListNode* pNode = tSkipListIterGet(iter);
     
-    STable* t = *(STable**)SL_GET_NODE_DATA(pNode);
-    taosArrayPush(list, &t->tableId);
+    STableIndexElem* elem = (STableIndexElem*)(SL_GET_NODE_DATA((SSkipListNode*) pNode));
+    taosArrayPush(list, &elem->pTable->tableId);
   }
   
   tSkipListDestroyIter(iter);
@@ -1235,6 +1231,7 @@ static int32_t getAllTableIdList(STable* pSuperTable, SArray* list) {
 
 /**
  * convert the result pointer to table id instead of table object pointer
+ * todo remove it by using callback function to change the final result in-time.
  * @param pRes
  */
 static void convertQueryResult(SArray* pRes, SArray* pTableList) {
@@ -1244,8 +1241,8 @@ static void convertQueryResult(SArray* pRes, SArray* pTableList) {
 
   size_t size = taosArrayGetSize(pTableList);
   for (int32_t i = 0; i < size; ++i) {  // todo speedup  by using reserve space.
-    STable* pTable = taosArrayGetP(pTableList, i);
-    taosArrayPush(pRes, &pTable->tableId);
+    STableIndexElem* elem = taosArrayGet(pTableList, i);
+    taosArrayPush(pRes, &elem->pTable->tableId);
   }
 }
 
@@ -1309,7 +1306,12 @@ void filterPrepare(void* expr, void* param) {
     pInfo->q = (char*) pCond->arr;
   } else {
     pInfo->q = calloc(1, pSchema->bytes);
-    tVariantDump(pCond, pInfo->q, pSchema->type);
+    if (pSchema->type == TSDB_DATA_TYPE_BINARY || pSchema->type == TSDB_DATA_TYPE_NCHAR) {
+      varDataSetLen(pInfo->q, pCond->nLen);
+      tVariantDump(pCond, varDataVal(pInfo->q), pSchema->type);
+    } else {
+      tVariantDump(pCond, pInfo->q, pSchema->type);
+    }
   }
 }
 
@@ -1341,16 +1343,16 @@ int32_t tableGroupComparFn(const void *p1, const void *p2, const void *param) {
     int32_t bytes = 0;
     
     if (colIndex == TSDB_TBNAME_COLUMN_INDEX) {
-      f1 = pTable1->name;
-      f2 = pTable2->name;
+      f1 = (char*) pTable1->name;
+      f2 = (char*) pTable2->name;
       type = TSDB_DATA_TYPE_BINARY;
-      bytes = TSDB_TABLE_NAME_LEN;
+      bytes = TSDB_TABLE_NAME_LEN + VARSTR_HEADER_SIZE;
     } else {
-      f1 = dataRowTuple(pTable1->tagVal);
-      f2 = dataRowTuple(pTable2->tagVal);
-
-      type = schemaColAt(pTableGroupSupp->pTagSchema, colIndex)->type;
-      bytes = schemaColAt(pTableGroupSupp->pTagSchema, colIndex)->bytes;
+      STColumn* pCol = schemaColAt(pTableGroupSupp->pTagSchema, colIndex);
+      bytes = pCol->bytes;
+  
+      f1 = tdGetRowDataOfCol(pTable1->tagVal, pCol->type, TD_DATA_ROW_HEAD_SIZE + pCol->offset);
+      f2 = tdGetRowDataOfCol(pTable2->tagVal, pCol->type, TD_DATA_ROW_HEAD_SIZE + pCol->offset);
     }
     
     int32_t ret = doCompare(f1, f2, type, bytes);
@@ -1428,24 +1430,20 @@ SArray* createTableGroup(SArray* pTableList, STSchema* pTagSchema, SColIndex* pC
 
 bool tSkipListNodeFilterCallback(const void* pNode, void* param) {
   tQueryInfo* pInfo = (tQueryInfo*) param;
-
-  STable* pTable = *(STable**)(SL_GET_NODE_DATA((SSkipListNode*)pNode));
+  
+  STableIndexElem* elem = (STableIndexElem*)(SL_GET_NODE_DATA((SSkipListNode*)pNode));
 
   char*  val = NULL;
   int8_t type = pInfo->sch.type;
 
   if (pInfo->colIndex == TSDB_TBNAME_COLUMN_INDEX) {
-    val = pTable->name;
+    val = (char*) elem->pTable->name;
     type = TSDB_DATA_TYPE_BINARY;
   } else {
     STSchema* pTSchema = (STSchema*) pInfo->param; // todo table schema is identical to stable schema??
     
     int32_t offset = pTSchema->columns[pInfo->colIndex].offset;
-    if (pInfo->sch.type == TSDB_DATA_TYPE_BINARY || pInfo->sch.type == TSDB_DATA_TYPE_NCHAR) {
-      val = tdGetRowDataOfCol(pTable->tagVal, pInfo->sch.type, TD_DATA_ROW_HEAD_SIZE + offset);
-    } else {
-      val = dataRowTuple(pTable->tagVal) + offset;
-    }
+    val = tdGetRowDataOfCol(elem->pTable->tagVal, pInfo->sch.type, TD_DATA_ROW_HEAD_SIZE + offset);
   }
 
   int32_t ret = 0;
@@ -1456,8 +1454,6 @@ bool tSkipListNodeFilterCallback(const void* pNode, void* param) {
       ret = pInfo->compare(val, pInfo->q);
     }
   } else {
-//    tVariant t = {0};
-//    tVariantCreateFromBinary(&t, val, (uint32_t)pInfo->sch.bytes, type);
     ret = pInfo->compare(val, pInfo->q);
   }
 
@@ -1502,7 +1498,7 @@ static int32_t doQueryTableList(STable* pSTable, SArray* pRes, tExprNode* pExpr)
       .pExtInfo = pSTable->tagSchema,
       };
 
-  SArray* pTableList = taosArrayInit(8, POINTER_BYTES);
+  SArray* pTableList = taosArrayInit(8, sizeof(STableIndexElem));
 
   tExprTreeTraverse(pExpr, pSTable->pIndex, pTableList, &supp);
   tExprTreeDestroy(&pExpr, destroyHelper);
diff --git a/src/util/src/talgo.c b/src/util/src/talgo.c
index 32978453fc676cfb8d47fca10483471d275ad7e9..f343912cde267855bc083fbde47f380e9609742e 100644
--- a/src/util/src/talgo.c
+++ b/src/util/src/talgo.c
@@ -144,11 +144,11 @@ static void tqsortImpl(void *src, int32_t start, int32_t end, size_t size, const
   }
   
   if (leftPartEnd > start) {
-    tqsortImpl(src, size, start, leftPartEnd, param, comparFn, buf);
+    tqsortImpl(src, start, leftPartEnd, size, param, comparFn, buf);
   }
   
   if (rightPartStart < end) {
-    tqsortImpl(src, size, rightPartStart, end, param, comparFn, buf);
+    tqsortImpl(src, rightPartStart, end, size, param, comparFn, buf);
   }
 }
 
diff --git a/src/util/src/tcompare.c b/src/util/src/tcompare.c
index 2d6ae13f97b8394074eb265ac1a78a34fe5cf527..643f54550b0c3f2617abf2a539d2ddad7e6e1f57 100644
--- a/src/util/src/tcompare.c
+++ b/src/util/src/tcompare.c
@@ -60,8 +60,15 @@ int32_t compareDoubleVal(const void *pLeft, const void *pRight) {
   }
 }
 
-int32_t compareStrVal(const void *pLeft, const void *pRight) {
-  return (int32_t)strcmp(pLeft, pRight);
+int32_t compareLenPrefixedStr(const void *pLeft, const void *pRight) {
+  int32_t len1 = varDataLen(pLeft);
+  int32_t len2 = varDataLen(pRight);
+  
+  if (len1 != len2) {
+    return len1 > len2? 1:-1;
+  } else {
+    return (int32_t) strncmp(varDataVal(pLeft), varDataVal(pRight), len1);
+  }
 }
 
 int32_t compareWStrVal(const void *pLeft, const void *pRight) {
@@ -267,7 +274,7 @@ __compar_fn_t getComparFunc(int32_t type, int32_t optr) {
       } else if (optr == TSDB_RELATION_IN) {
         comparFn = compareFindStrInArray;
       } else { /* normal relational comparFn */
-        comparFn = compareStrVal;
+        comparFn = compareLenPrefixedStr;
       }
     
       break;
@@ -296,6 +303,7 @@ __compar_fn_t getKeyComparFunc(int32_t keyType) {
   
   switch (keyType) {
     case TSDB_DATA_TYPE_TINYINT:
+    case TSDB_DATA_TYPE_BOOL:
       comparFn = compareInt8Val;
       break;
     case TSDB_DATA_TYPE_SMALLINT:
@@ -308,17 +316,13 @@ __compar_fn_t getKeyComparFunc(int32_t keyType) {
     case TSDB_DATA_TYPE_TIMESTAMP:
       comparFn = compareInt64Val;
       break;
-    case TSDB_DATA_TYPE_BOOL:
-      comparFn = compareInt32Val;
-      break;
-    
     case TSDB_DATA_TYPE_FLOAT:
     case TSDB_DATA_TYPE_DOUBLE:
       comparFn = compareDoubleVal;
       break;
     
     case TSDB_DATA_TYPE_BINARY:
-      comparFn = compareStrVal;
+      comparFn = compareLenPrefixedStr;
       break;
     
     case TSDB_DATA_TYPE_NCHAR:
@@ -349,13 +353,20 @@ int32_t doCompare(const char* f1, const char* f2, int32_t type, size_t size) {
       }
       return (ret < 0) ? -1 : 1;
     }
-    default: {
-      int32_t ret = strncmp(f1, f2, (size_t)size);
-      if (ret == 0) {
-        return ret;
-      }
+    default: {  // todo refactor
+      tstr* t1 = (tstr*) f1;
+      tstr* t2 = (tstr*) f2;
       
-      return (ret < 0) ? -1 : 1;
+      if (t1->len != t2->len) {
+        return t1->len > t2->len? 1:-1;
+      } else {
+        int32_t ret = strncmp(t1->data, t2->data, t1->len);
+        if (ret == 0) {
+          return 0;
+        } else {
+          return ret < 0? -1:1;
+        }
+      }
     }
   }
 }
diff --git a/tests/script/general/cache/restart_metrics.sim b/tests/script/general/cache/restart_metrics.sim
index dbd15b945f6cb855a67f2531547af8c95b874897..c85a66869ac6cc24fc14645ccf1aa4fc7a1f4e8f 100644
--- a/tests/script/general/cache/restart_metrics.sim
+++ b/tests/script/general/cache/restart_metrics.sim
@@ -27,11 +27,15 @@ sql create table $tb using $mt tags( "1" )
 sql insert into $tb values (now, 1)
 
 sql select * from $tb
-print ===>rows $rows, data $data01
+#print ===>rows $rows, data $data01
+
 if $rows != 1 then
+  print expect 1, actual: $rows
   return -1
-endi  
+endi
+
 if $data01 != 1 then
+  print expect 1 actual: $data01
   return -1
 endi  
 
@@ -66,8 +70,10 @@ sql select * from $tb
 print ===>rows $rows, data $data01
 if $rows != 1 then
   return -1
-endi  
+endi
+
 if $data01 != 1 then
+  print expect 1, actual $data01
   return -1
 endi  
 
@@ -80,6 +86,7 @@ if $data01 != 1 then
   return -1
 endi  
 if $data02 != 3 then
+  print expect 3 actual: $data02
   return -1
 endi 
 
diff --git a/tests/script/general/field/bigint.sim b/tests/script/general/field/bigint.sim
index 5cca73595c9159c8da8cea31e24471814f8f9771..10060f7422f50ccbb36b118d9dbfbc7729059e3f 100644
--- a/tests/script/general/field/bigint.sim
+++ b/tests/script/general/field/bigint.sim
@@ -132,7 +132,9 @@ endi
 print =============== step6
 sql select count(tbcol), avg(tbcol), sum(tbcol), min(tbcol), max(tbcol), first(tbcol), last(tbcol) from $mt where tbcol = 1 group by tgcol
 print $data00 $data01 $data02 $data03 $data04 $data05 $data06 
-if $data00 != 100 then 
+print $data10 $data11 $data12 $data13 $data14 $data15 $data16
+if $data00 != 100 then
+  print expect 100, actual $data00
   return -1
 endi
 
diff --git a/tests/script/general/parser/testSuite.sim b/tests/script/general/parser/testSuite.sim
index aaf8979337f8914d0fc2aa50aceda2cff6c8bd71..0719d1c330c42ad983696f256ae7240bf049bfab 100644
--- a/tests/script/general/parser/testSuite.sim
+++ b/tests/script/general/parser/testSuite.sim
@@ -1,113 +1,97 @@
-# run general/parser/alter.sim
-# sleep 2000
-# run general/parser/alter1.sim
-# sleep 2000
-# run general/parser/alter_stable.sim
-# sleep 2000
-# run general/parser/auto_create_tb.sim
-# sleep 2000
-# run general/parser/auto_create_tb_drop_tb.sim
-# sleep 2000
+#run general/parser/alter.sim
+#sleep 2000
+#run general/parser/alter1.sim
+#sleep 2000
+#run general/parser/alter_stable.sim
+#sleep 2000
+#run general/parser/auto_create_tb.sim
+#sleep 2000
+#run general/parser/auto_create_tb_drop_tb.sim
 
-run general/parser/binary_escapeCharacter.sim
-sleep 2000
-run general/parser/bug.sim
 sleep 2000
 run general/parser/col_arithmetic_operation.sim
 sleep 2000
-run general/parser/columnValue_bigint.sim
+run general/parser/columnValue.sim
 sleep 2000
-run general/parser/columnValue_bool.sim
+run general/parser/commit.sim
 sleep 2000
-run general/parser/columnValue_double.sim
+run general/parser/create_db.sim
 sleep 2000
-run general/parser/columnValue_float.sim
+run general/parser/create_mt.sim
 sleep 2000
-run general/parser/columnValue_int.sim
+run general/parser/create_tb.sim
+sleep 2000
+run general/parser/dbtbnameValidate.sim
+sleep 2000
+run general/parser/import_commit1.sim
+sleep 2000
+run general/parser/import_commit2.sim
+sleep 2000
+run general/parser/import_commit3.sim
+sleep 2000
+run general/parser/insert_tb.sim
+sleep 2000
+run general/parser/first_last.sim
+sleep 2000
+run general/parser/import_file.sim
+sleep 2000
+run general/parser/fill.sim
+sleep 2000
+run general/parser/fill_stb.sim
+sleep 2000
+run general/parser/tags_dynamically_specifiy.sim
+sleep 2000
+run general/parser/interp.sim
+run general/parser/lastrow.sim
+sleep 2000
+run general/parser/limit.sim
+sleep 2000
+run general/parser/limit1.sim
+sleep 2000
+run general/parser/limit1_tblocks100.sim
+sleep 2000
+run general/parser/limit2.sim
+sleep 2000
+run general/parser/mixed_blocks.sim
+sleep 2000
+run general/parser/nchar.sim
+sleep 2000
+run general/parser/null_char.sim
+sleep 2000
+run general/parser/selectResNum.sim
+sleep 2000
+run general/parser/select_across_vnodes.sim
 sleep 2000
-
-# sleep 2000
-# run general/parser/col_arithmetic_operation.sim
-# sleep 2000
-# run general/parser/columnValue.sim
-# sleep 2000
-# run general/parser/commit.sim
-# run general/parser/create_db.sim
-# sleep 2000
-# run general/parser/create_mt.sim
-# sleep 2000
-# run general/parser/create_tb.sim
-# sleep 2000
-# run general/parser/dbtbnameValidate.sim
-# sleep 2000
-# run general/parser/fill.sim
-# sleep 2000
-# run general/parser/fill_stb.sim
-# sleep 2000
-# run general/parser/first_last.sim
-# sleep 2000
-# run general/parser/import_commit1.sim
-# sleep 2000
-# run general/parser/import_commit2.sim
-# sleep 2000
-# run general/parser/import_commit3.sim
-# sleep 2000
-# run general/parser/import_file.sim
-# sleep 2000
-# run general/parser/insert_tb.sim
-# sleep 2000
-# run general/parser/tags_dynamically_specifiy.sim
-# sleep 2000
-# run general/parser/interp.sim
-# run general/parser/lastrow.sim
-# sleep 2000
-# run general/parser/limit.sim
-# sleep 2000
-# run general/parser/limit1.sim
-# sleep 2000
-# run general/parser/limit1_tblocks100.sim
-# sleep 2000
-# run general/parser/limit2.sim
-# sleep 2000
-# run general/parser/mixed_blocks.sim
-# sleep 2000
-# run general/parser/nchar.sim
-# sleep 2000
-# run general/parser/null_char.sim
-# sleep 2000
-# run general/parser/selectResNum.sim
-# sleep 2000
-# run general/parser/select_across_vnodes.sim
-# sleep 2000
 run general/parser/select_from_cache_disk.sim
 sleep 2000
-# run general/parser/set_tag_vals.sim
-# sleep 2000
-# run general/parser/single_row_in_tb.sim
-# sleep 2000
-# run general/parser/slimit.sim
-# sleep 2000
+run general/parser/set_tag_vals.sim
+sleep 2000
+run general/parser/single_row_in_tb.sim
+sleep 2000
+run general/parser/slimit.sim
+sleep 2000
 run general/parser/slimit1.sim
 sleep 2000
-run general/parser/slimit1_query.sim
-sleep 2000
-# run general/parser/slimit_alter_tags.sim
-# sleep 2000
-# run general/parser/stream_on_sys.sim
-# sleep 2000
-# run general/parser/stream.sim
-# sleep 2000
-# run general/parser/tbnameIn.sim
-# sleep 2000
-# run general/parser/where.sim
-# sleep 2000
-# #run general/parser/repeatAlter.sim
-# sleep 2000
-# #run general/parser/repeatStream.sim
-# sleep 2000
-# run general/parser/join.sim
-# run general/parser/join_multivnode.sim
-# run general/parser/projection_limit_offset.sim
-# sleep 2000
-# run general/parser/select_with_tags.sim
-# run general/parser/groupby.sim
+run general/parser/slimit_alter_tags.sim
+sleep 2000
+run general/parser/stream_on_sys.sim
+sleep 2000
+run general/parser/stream.sim
+sleep 2000
+run general/parser/tbnameIn.sim
+sleep 2000
+run general/parser/where.sim
+sleep 2000
+#run general/parser/repeatAlter.sim
+sleep 2000
+#run general/parser/repeatStream.sim
+sleep 2000
+run general/parser/join.sim
+sleep 2000
+run general/parser/join_multivnode.sim
+sleep 2000
+run general/parser/projection_limit_offset.sim
+sleep 2000
+run general/parser/select_with_tags.sim
+sleep 2000
+run general/parser/groupby.sim
diff --git a/tests/script/general/tag/bool.sim b/tests/script/general/tag/bool.sim
index 540eaf123872d3cbdba15fd3556866802992be9a..349cb738bffbb216305af0718611987ae7f20f9c 100644
--- a/tests/script/general/tag/bool.sim
+++ b/tests/script/general/tag/bool.sim
@@ -122,7 +122,8 @@ if $rows != 100 then
   return -1
 endi
 sql select * from $mt where tgcol = 1
-if $rows != 100 then 
+if $rows != 100 then
+  print expect 100, actual:$rows
   return -1
 endi
 sql select * from $mt where tgcol <> 1
diff --git a/tests/script/general/tag/filter.sim b/tests/script/general/tag/filter.sim
index 4388f029f9c84b707ae564962e398c098b4b5529..75a6ed00da6d3b8173b748961d42ab8f909e7ef1 100644
--- a/tests/script/general/tag/filter.sim
+++ b/tests/script/general/tag/filter.sim
@@ -122,7 +122,8 @@ endi
 print =============== step14
 sql select count(tbcol) as c from $mt where ts > 1000 group by tgcol
 print $data00 $data01 $data02 $data03 $data04 $data05 $data06 
-if $data00 != 100 then 
+if $data00 != 100 then
+  print expect 100, actual $data00
   return -1
 endi
 
diff --git a/tests/script/test.sh b/tests/script/test.sh
index 743597eabd1a301cc45990bce12f5727f18042e0..8e3959a680b8e3d908645802db2d93c946aa4d62 100755
--- a/tests/script/test.sh
+++ b/tests/script/test.sh
@@ -99,7 +99,8 @@ echo "cDebugFlag       135"                  >> $TAOS_CFG
 echo "httpDebugFlag    135"                  >> $TAOS_CFG
 echo "monitorDebugFlag 135"                  >> $TAOS_CFG
 echo "udebugFlag       135"                  >> $TAOS_CFG
-echo "clog             0"                    >> $TAOS_CFG
+echo "tablemetakeeptimer 5"                  >> $TAOS_CFG
+echo "wal              0"                    >> $TAOS_CFG
 echo "asyncLog         0"                    >> $TAOS_CFG
 echo "locale           en_US.UTF-8"          >> $TAOS_CFG
 echo " "                                     >> $TAOS_CFG