refactor(query): do some internal refactor for executor.

source/libs/executor/inc/executorimpl.h

@@ -407,6 +407,12 @@ typedef struct SAggSupporter {
   int32_t        resultRowSize;        // the result buffer size for each result row, with the meta data size for each row
 } SAggSupporter;
 
+typedef struct STimeWindowSupp {
+  int8_t           calTrigger;
+  int64_t          waterMark;
+  SColumnInfoData  timeWindowData;     // query time window info for scalar function execution.
+} STimeWindowAggSupp;
+
 typedef struct STableIntervalOperatorInfo {
   SOptrBasicInfo     binfo;              // basic info
   SGroupResInfo      groupResInfo;       // multiple results build supporter
@@ -420,9 +426,7 @@ typedef struct STableIntervalOperatorInfo {
   int32_t            order;              // current SSDataBlock scan order
   EOPTR_EXEC_MODEL   execModel;          // operator execution model [batch model|stream model]
   SArray*            pUpdatedWindow;     // updated time window due to the input data block from the downstream operator.
-  SColumnInfoData  timeWindowData;     // query time window info for scalar function execution.
-  double           watermark;          // water mark
-  int32_t          trigger;            // trigger model
+  STimeWindowAggSupp twAggSup;
 } STableIntervalOperatorInfo;
 
 typedef struct SAggOperatorInfo {
@@ -506,7 +510,6 @@ typedef struct SPartitionOperatorInfo {
   SDiskbasedBuf* pBuf;          // query result buffer based on blocked-wised disk file
   int32_t        rowCapacity;   // maximum number of rows for each buffer page
   int32_t*       columnOffset;  // start position for each column data
-
   void*          pGroupIter;  // group iterator
   int32_t        pageIndex;   // page index of current group
 } SPartitionOperatorInfo;
@@ -525,7 +528,7 @@ typedef struct SSessionAggOperatorInfo {
   SWindowRowsSup     winSup;
   bool               reptScan;        // next round scan
   int64_t            gap;             // session window gap
-  SColumnInfoData timeWindowData;  // query time window info for scalar function execution.
+  STimeWindowAggSupp twAggSup;
 } SSessionAggOperatorInfo;
 
 typedef struct STimeSliceOperatorInfo {
@@ -542,7 +545,7 @@ typedef struct SStateWindowOperatorInfo {
   int32_t            colIndex;  // start row index
   bool               hasKey;
   SStateKeys         stateKey;
-  SColumnInfoData timeWindowData;  // query time window info for scalar function execution.
+  STimeWindowAggSupp twAggSup;
   //  bool             reptScan;
 } SStateWindowOperatorInfo;
 
@@ -640,10 +643,11 @@ SOperatorInfo* createSysTableScanOperatorInfo(void* pSysTableReadHandle, SSDataB
                                               SNode* pCondition, SEpSet epset, SArray* colList,
                                               SExecTaskInfo* pTaskInfo, bool showRewrite, int32_t accountId);
 SOperatorInfo* createIntervalOperatorInfo(SOperatorInfo* downstream, SExprInfo* pExprInfo, int32_t numOfCols,
-                                          SSDataBlock* pResBlock, SInterval* pInterval, int32_t primaryTsSlot,
-                                          const STableGroupInfo* pTableGroupInfo, SExecTaskInfo* pTaskInfo);
+                                          SSDataBlock* pResBlock, SInterval* pInterval, int32_t primaryTsSlotId,
+                                          STimeWindowAggSupp *pTwAggSupp, const STableGroupInfo* pTableGroupInfo,
+                                          SExecTaskInfo* pTaskInfo);
 SOperatorInfo* createSessionAggOperatorInfo(SOperatorInfo* downstream, SExprInfo* pExprInfo, int32_t numOfCols,
-                                            SSDataBlock* pResBlock, int64_t gap, SExecTaskInfo* pTaskInfo);
+                                            SSDataBlock* pResBlock, int64_t gap, STimeWindowAggSupp *pTwAggSupp, SExecTaskInfo* pTaskInfo);
 SOperatorInfo* createGroupOperatorInfo(SOperatorInfo* downstream, SExprInfo* pExprInfo, int32_t numOfCols,
                                        SSDataBlock* pResultBlock, SArray* pGroupColList, SNode* pCondition,
                                        SExprInfo* pScalarExprInfo, int32_t numOfScalarExpr, SExecTaskInfo* pTaskInfo,
@@ -656,7 +660,7 @@ SOperatorInfo* createFillOperatorInfo(SOperatorInfo* downstream, SExprInfo* pExp
                                       SInterval* pInterval, SSDataBlock* pResBlock, int32_t fillType, char* fillVal,
                                       bool multigroupResult, SExecTaskInfo* pTaskInfo);
 SOperatorInfo* createStatewindowOperatorInfo(SOperatorInfo* downstream, SExprInfo* pExpr, int32_t numOfCols,
-                                             SSDataBlock* pResBlock, SExecTaskInfo* pTaskInfo);
+                                             SSDataBlock* pResBlock, STimeWindowAggSupp *pTwAggSupp, SExecTaskInfo* pTaskInfo);
 
 SOperatorInfo* createPartitionOperatorInfo(SOperatorInfo* downstream, SExprInfo* pExprInfo, int32_t numOfCols,
                                            SSDataBlock* pResultBlock, SArray* pGroupColList, SExecTaskInfo* pTaskInfo,

source/libs/executor/src/executorimpl.c

@@ -1097,6 +1097,8 @@ static int32_t doSetInputDataBlock(SOperatorInfo* pOperator, SqlFunctionCtx* pCt
         pInput->totalRows = pBlock->info.rows;
         pInput->numOfRows = pBlock->info.rows;
         pInput->startRowIndex = 0;
+
+        pInput->pPTS = taosArrayGet(pBlock->pDataBlock, 0); // todo set the correct timestamp column
         ASSERT(pInput->pData[j] != NULL);
       } else if (pFuncParam->type == FUNC_PARAM_TYPE_VALUE) {
         if (createDummyCol) {
@@ -1516,8 +1518,8 @@ static SArray* hashIntervalAgg(SOperatorInfo* pOperatorInfo, SResultRowInfo* pRe
   // window start key interpolation
   doWindowBorderInterpolation(pOperatorInfo, pSDataBlock, pInfo->binfo.pCtx, pResult, &win, startPos, forwardStep, pInfo->order, false);
 
-  updateTimeWindowInfo(&pInfo->timeWindowData, &win, true);
-  doApplyFunctions(pInfo->binfo.pCtx, &win, &pInfo->timeWindowData, startPos, forwardStep, tsCols, pSDataBlock->info.rows, numOfOutput, TSDB_ORDER_ASC);
+  updateTimeWindowInfo(&pInfo->twAggSup.timeWindowData, &win, true);
+  doApplyFunctions(pInfo->binfo.pCtx, &win, &pInfo->twAggSup.timeWindowData, startPos, forwardStep, tsCols, pSDataBlock->info.rows, numOfOutput, TSDB_ORDER_ASC);
 
   STimeWindow nextWin = win;
   while (1) {
@@ -1548,8 +1550,8 @@ static SArray* hashIntervalAgg(SOperatorInfo* pOperatorInfo, SResultRowInfo* pRe
     doWindowBorderInterpolation(pOperatorInfo, pSDataBlock, pInfo->binfo.pCtx, pResult, &nextWin, startPos, forwardStep,
                                 pInfo->order, false);
 
-    updateTimeWindowInfo(&pInfo->timeWindowData, &nextWin, true);
-    doApplyFunctions(pInfo->binfo.pCtx, &nextWin, &pInfo->timeWindowData, startPos, forwardStep, tsCols, pSDataBlock->info.rows, numOfOutput, TSDB_ORDER_ASC);
+    updateTimeWindowInfo(&pInfo->twAggSup.timeWindowData, &nextWin, true);
+    doApplyFunctions(pInfo->binfo.pCtx, &nextWin, &pInfo->twAggSup.timeWindowData, startPos, forwardStep, tsCols, pSDataBlock->info.rows, numOfOutput, TSDB_ORDER_ASC);
   }
 
   if (pInfo->timeWindowInterpo) {
@@ -1620,8 +1622,8 @@ static void doSessionWindowAggImpl(SOperatorInfo* pOperator, SSessionAggOperator
       }
 
       // pInfo->numOfRows data belong to the current session window
-      updateTimeWindowInfo(&pInfo->timeWindowData, &window, false);
-      doApplyFunctions(pInfo->binfo.pCtx, &window, &pInfo->timeWindowData, pRowSup->startRowIndex, pRowSup->numOfRows, NULL, pBlock->info.rows, numOfOutput, TSDB_ORDER_ASC);
+      updateTimeWindowInfo(&pInfo->twAggSup.timeWindowData, &window, false);
+      doApplyFunctions(pInfo->binfo.pCtx, &window, &pInfo->twAggSup.timeWindowData, pRowSup->startRowIndex, pRowSup->numOfRows, NULL, pBlock->info.rows, numOfOutput, TSDB_ORDER_ASC);
 
       // here we start a new session window
       doKeepNewWindowStartInfo(pRowSup, tsList, j);
@@ -1637,8 +1639,8 @@ static void doSessionWindowAggImpl(SOperatorInfo* pOperator, SSessionAggOperator
     longjmp(pTaskInfo->env, TSDB_CODE_QRY_APP_ERROR);
   }
 
-  updateTimeWindowInfo(&pInfo->timeWindowData, &pRowSup->win, false);
-  doApplyFunctions(pInfo->binfo.pCtx, &pRowSup->win, &pInfo->timeWindowData, pRowSup->startRowIndex, pRowSup->numOfRows, NULL, pBlock->info.rows, numOfOutput, TSDB_ORDER_ASC);
+  updateTimeWindowInfo(&pInfo->twAggSup.timeWindowData, &pRowSup->win, false);
+  doApplyFunctions(pInfo->binfo.pCtx, &pRowSup->win, &pInfo->twAggSup.timeWindowData, pRowSup->startRowIndex, pRowSup->numOfRows, NULL, pBlock->info.rows, numOfOutput, TSDB_ORDER_ASC);
 }
 
 static void setResultRowKey(SResultRow* pResultRow, char* pData, int16_t type) {
@@ -5338,8 +5340,8 @@ static void doStateWindowAggImpl(SOperatorInfo* pOperator, SStateWindowOperatorI
         longjmp(pTaskInfo->env, TSDB_CODE_QRY_APP_ERROR);
       }
 
-      updateTimeWindowInfo(&pInfo->timeWindowData, &window, false);
-      doApplyFunctions(pInfo->binfo.pCtx, &window, &pInfo->timeWindowData, pRowSup->startRowIndex, pRowSup->numOfRows, NULL, pBlock->info.rows, numOfOutput, TSDB_ORDER_ASC);
+      updateTimeWindowInfo(&pInfo->twAggSup.timeWindowData, &window, false);
+      doApplyFunctions(pInfo->binfo.pCtx, &window, &pInfo->twAggSup.timeWindowData, pRowSup->startRowIndex, pRowSup->numOfRows, NULL, pBlock->info.rows, numOfOutput, TSDB_ORDER_ASC);
 
       // here we start a new session window
       doKeepNewWindowStartInfo(pRowSup, tsList, j);
@@ -5355,8 +5357,8 @@ static void doStateWindowAggImpl(SOperatorInfo* pOperator, SStateWindowOperatorI
     longjmp(pTaskInfo->env, TSDB_CODE_QRY_APP_ERROR);
   }
 
-  updateTimeWindowInfo(&pInfo->timeWindowData, &pRowSup->win, false);
-  doApplyFunctions(pInfo->binfo.pCtx, &pRowSup->win, &pInfo->timeWindowData, pRowSup->startRowIndex, pRowSup->numOfRows, NULL, pBlock->info.rows, numOfOutput, TSDB_ORDER_ASC);
+  updateTimeWindowInfo(&pInfo->twAggSup.timeWindowData, &pRowSup->win, false);
+  doApplyFunctions(pInfo->binfo.pCtx, &pRowSup->win, &pInfo->twAggSup.timeWindowData, pRowSup->startRowIndex, pRowSup->numOfRows, NULL, pBlock->info.rows, numOfOutput, TSDB_ORDER_ASC);
 }
 
 static SSDataBlock* doStateWindowAgg(SOperatorInfo* pOperator, bool* newgroup) {
@@ -5863,8 +5865,9 @@ _error:
 }
 
 SOperatorInfo* createIntervalOperatorInfo(SOperatorInfo* downstream, SExprInfo* pExprInfo, int32_t numOfCols,
-                                          SSDataBlock* pResBlock, SInterval* pInterval, int32_t primaryTsSlot,
-                                          const STableGroupInfo* pTableGroupInfo, SExecTaskInfo* pTaskInfo) {
+                                          SSDataBlock* pResBlock, SInterval* pInterval, int32_t primaryTsSlotId,
+                                          STimeWindowAggSupp *pTwAggSupp, const STableGroupInfo* pTableGroupInfo,
+                                          SExecTaskInfo* pTaskInfo) {
   STableIntervalOperatorInfo* pInfo = taosMemoryCalloc(1, sizeof(STableIntervalOperatorInfo));
   SOperatorInfo*              pOperator = taosMemoryCalloc(1, sizeof(SOperatorInfo));
   if (pInfo == NULL || pOperator == NULL) {
@@ -5874,19 +5877,18 @@ SOperatorInfo* createIntervalOperatorInfo(SOperatorInfo* downstream, SExprInfo*
   pInfo->order          = TSDB_ORDER_ASC;
   pInfo->interval       = *pInterval;
   pInfo->execModel      = pTaskInfo->execModel;
-
   pInfo->win            = pTaskInfo->window;
   pInfo->win.skey       = 0;
   pInfo->win.ekey       = INT64_MAX;
-
-  pInfo->primaryTsIndex = primaryTsSlot;
+  pInfo->primaryTsIndex = primaryTsSlotId;
+  pInfo->twAggSup       = *pTwAggSupp;
 
   int32_t numOfRows = 4096;
   size_t keyBufSize = sizeof(int64_t) + sizeof(int64_t) + POINTER_BYTES;
 
   initResultSizeInfo(pOperator, numOfRows);
   int32_t code = initAggInfo(&pInfo->binfo, &pInfo->aggSup, pExprInfo, numOfCols, pResBlock, keyBufSize, pTaskInfo->id.str);
-  initExecTimeWindowInfo(&pInfo->timeWindowData, &pInfo->win);
+  initExecTimeWindowInfo(&pInfo->twAggSup.timeWindowData, &pInfo->win);
 
   //  pInfo->pTableQueryInfo = initTableQueryInfo(pTableGroupInfo);
   if (code != TSDB_CODE_SUCCESS /* || pInfo->pTableQueryInfo == NULL*/) {
@@ -5955,7 +5957,8 @@ SOperatorInfo* createTimeSliceOperatorInfo(SOperatorInfo* downstream, SExprInfo*
   return NULL;
 }
 
-SOperatorInfo* createStatewindowOperatorInfo(SOperatorInfo* downstream, SExprInfo* pExpr, int32_t numOfCols, SSDataBlock* pResBlock, SExecTaskInfo* pTaskInfo) {
+SOperatorInfo* createStatewindowOperatorInfo(SOperatorInfo* downstream, SExprInfo* pExpr, int32_t numOfCols, SSDataBlock* pResBlock, STimeWindowAggSupp *pTwAggSup,
+    SExecTaskInfo* pTaskInfo) {
   SStateWindowOperatorInfo* pInfo = taosMemoryCalloc(1, sizeof(SStateWindowOperatorInfo));
   SOperatorInfo* pOperator = taosMemoryCalloc(1, sizeof(SOperatorInfo));
   if (pInfo == NULL || pOperator == NULL) {
@@ -5969,6 +5972,9 @@ SOperatorInfo* createStatewindowOperatorInfo(SOperatorInfo* downstream, SExprInf
   initAggInfo(&pInfo->binfo, &pInfo->aggSup, pExpr, numOfCols, pResBlock, keyBufSize, pTaskInfo->id.str);
   initResultRowInfo(&pInfo->binfo.resultRowInfo, 8);
 
+  pInfo->twAggSup = *pTwAggSup;
+  initExecTimeWindowInfo(&pInfo->twAggSup.timeWindowData, &pTaskInfo->window);
+
   pOperator->name         = "StateWindowOperator";
   pOperator->operatorType = QUERY_NODE_PHYSICAL_PLAN_STATE_WINDOW;
   pOperator->blockingOptr = true;
@@ -5992,7 +5998,7 @@ SOperatorInfo* createStatewindowOperatorInfo(SOperatorInfo* downstream, SExprInf
 }
 
 SOperatorInfo* createSessionAggOperatorInfo(SOperatorInfo* downstream, SExprInfo* pExprInfo, int32_t numOfCols,
-                                            SSDataBlock* pResBlock, int64_t gap, SExecTaskInfo* pTaskInfo) {
+                                            SSDataBlock* pResBlock, int64_t gap, STimeWindowAggSupp *pTwAggSupp, SExecTaskInfo* pTaskInfo) {
   SSessionAggOperatorInfo* pInfo = taosMemoryCalloc(1, sizeof(SSessionAggOperatorInfo));
   SOperatorInfo*           pOperator = taosMemoryCalloc(1, sizeof(SOperatorInfo));
   if (pInfo == NULL || pOperator == NULL) {
@@ -6008,8 +6014,9 @@ SOperatorInfo* createSessionAggOperatorInfo(SOperatorInfo* downstream, SExprInfo
     goto _error;
   }
 
+  pInfo->twAggSup = *pTwAggSupp;
   initResultRowInfo(&pInfo->binfo.resultRowInfo, 8);
-  initExecTimeWindowInfo(&pInfo->timeWindowData, &pTaskInfo->window);
+  initExecTimeWindowInfo(&pInfo->twAggSup.timeWindowData, &pTaskInfo->window);
 
   pInfo->gap              = gap;
   pInfo->binfo.pRes       = pResBlock;
@@ -6559,8 +6566,10 @@ SOperatorInfo* createOperatorTree(SPhysiNode* pPhyNode, SExecTaskInfo* pTaskInfo
         .precision    = ((SColumnNode*)pIntervalPhyNode->window.pTspk)->node.resType.precision
     };
 
+    STimeWindowAggSupp as = {.waterMark = pIntervalPhyNode->window.watermark, .calTrigger = pIntervalPhyNode->window.triggerType};
+
     int32_t primaryTsSlotId = ((SColumnNode*) pIntervalPhyNode->window.pTspk)->slotId;
-    pOptr = createIntervalOperatorInfo(ops[0], pExprInfo, num, pResBlock, &interval, primaryTsSlotId, pTableGroupInfo, pTaskInfo);
+    pOptr = createIntervalOperatorInfo(ops[0], pExprInfo, num, pResBlock, &interval, primaryTsSlotId, &as, pTableGroupInfo, pTaskInfo);
   } else if (QUERY_NODE_PHYSICAL_PLAN_SORT == type) {
     SSortPhysiNode* pSortPhyNode = (SSortPhysiNode*)pPhyNode;
 
@@ -6571,9 +6580,11 @@ SOperatorInfo* createOperatorTree(SPhysiNode* pPhyNode, SExecTaskInfo* pTaskInfo
   } else if (QUERY_NODE_PHYSICAL_PLAN_SESSION_WINDOW == type) {
     SSessionWinodwPhysiNode* pSessionNode = (SSessionWinodwPhysiNode*)pPhyNode;
 
+    STimeWindowAggSupp as = {.waterMark = pSessionNode->window.watermark, .calTrigger = pSessionNode->window.triggerType};
+
     SExprInfo*   pExprInfo = createExprInfo(pSessionNode->window.pFuncs, NULL, &num);
     SSDataBlock* pResBlock = createResDataBlock(pPhyNode->pOutputDataBlockDesc);
-    pOptr = createSessionAggOperatorInfo(ops[0], pExprInfo, num, pResBlock, pSessionNode->gap, pTaskInfo);
+    pOptr = createSessionAggOperatorInfo(ops[0], pExprInfo, num, pResBlock, pSessionNode->gap, &as, pTaskInfo);
   } else if (QUERY_NODE_PHYSICAL_PLAN_PARTITION == type) {
     SPartitionPhysiNode* pPartNode = (SPartitionPhysiNode*) pPhyNode;
     SArray* pColList = extractPartitionColInfo(pPartNode->pPartitionKeys);
@@ -6584,9 +6595,11 @@ SOperatorInfo* createOperatorTree(SPhysiNode* pPhyNode, SExecTaskInfo* pTaskInfo
   } else if (QUERY_NODE_PHYSICAL_PLAN_STATE_WINDOW == type) {
     SStateWinodwPhysiNode* pStateNode = (SStateWinodwPhysiNode*) pPhyNode;
 
+    STimeWindowAggSupp as = {.waterMark = pStateNode->window.watermark, .calTrigger = pStateNode->window.triggerType};
+
     SExprInfo* pExprInfo = createExprInfo(pStateNode->window.pFuncs, NULL, &num);
     SSDataBlock* pResBlock = createResDataBlock(pPhyNode->pOutputDataBlockDesc);
-    pOptr = createStatewindowOperatorInfo(ops[0], pExprInfo, num, pResBlock, pTaskInfo);
+    pOptr = createStatewindowOperatorInfo(ops[0], pExprInfo, num, pResBlock, &as, pTaskInfo);
   } else if (QUERY_NODE_PHYSICAL_PLAN_JOIN == type) {
     SJoinPhysiNode* pJoinNode = (SJoinPhysiNode*) pPhyNode;
     SSDataBlock* pResBlock = createResDataBlock(pPhyNode->pOutputDataBlockDesc);

source/libs/function/src/builtinsimpl.c

@@ -771,13 +771,9 @@ bool getFirstLastFuncEnv(SFunctionNode* pFunc, SFuncExecEnv* pEnv) {
   return true;
 }
 
-// TODO fix this
-// This ordinary first function only handle the data block in ascending order
+// This ordinary first function does not care if current scan is ascending order or descending order scan
+// the OPTIMIZED version of first function will only handle the ascending order scan
 int32_t firstFunction(SqlFunctionCtx *pCtx) {
-  if (pCtx->order == TSDB_ORDER_DESC) {
-    return 0;
-  }
-
   int32_t numOfElems = 0;
 
   SResultRowEntryInfo *pResInfo = GET_RES_INFO(pCtx);
@@ -786,29 +782,72 @@ int32_t firstFunction(SqlFunctionCtx *pCtx) {
   SInputColumnInfoData* pInput = &pCtx->input;
   SColumnInfoData* pInputCol = pInput->pData[0];
 
+  int32_t bytes = pInputCol->info.bytes;
+
   // All null data column, return directly.
   if (pInput->colDataAggIsSet && (pInput->pColumnDataAgg[0]->numOfNull == pInput->totalRows)) {
     ASSERT(pInputCol->hasNull == true);
     return 0;
   }
 
-  // Check for the first not null data
-  for (int32_t i = pInput->startRowIndex; i < pInput->numOfRows + pInput->startRowIndex; ++i) {
-    if (pInputCol->hasNull && colDataIsNull(pInputCol, pInput->totalRows, i, NULL)) {
+  SColumnDataAgg* pColAgg = (pInput->colDataAggIsSet)? pInput->pColumnDataAgg[0]:NULL;
+
+  TSKEY startKey = *(int64_t*)(pInput->pPTS ? colDataGetData(pInput->pPTS, 0) : 0);
+  TSKEY endKey = *(int64_t*)(pInput->pPTS ? colDataGetData(pInput->pPTS, pInput->totalRows - 1) : 0);
+
+  int32_t blockDataOrder = (startKey <= endKey)? TSDB_ORDER_ASC:TSDB_ORDER_DESC;
+
+  if (blockDataOrder == TSDB_ORDER_ASC) {
+    // filter according to current result firstly
+    if (pResInfo->numOfRes > 0) {
+      TSKEY ts = *(TSKEY*)(buf + bytes);
+      if (ts < startKey) {
+        return TSDB_CODE_SUCCESS;
+      }
+    }
+
+    for (int32_t i = pInput->startRowIndex; i < pInput->startRowIndex + pInput->numOfRows; ++i) {
+      if (pInputCol->hasNull && colDataIsNull(pInputCol, pInput->totalRows, i, pColAgg)) {
         continue;
       }
 
       char* data = colDataGetData(pInputCol, i);
-    memcpy(buf, data, pInputCol->info.bytes);
-    // TODO handle the subsidary value
-//    if (pCtx->ptsList != NULL) {
-//      TSKEY k = GET_TS_DATA(pCtx, i);
-//      DO_UPDATE_TAG_COLUMNS(pCtx, k);
-//    }
 
-    pResInfo->complete = true;
+      TSKEY cts = pCtx->ptsList ? GET_TS_DATA(pCtx, i) : 0;
+      if (pResInfo->numOfRes == 0 || *(TSKEY*)(buf + bytes) < cts) {
+        memcpy(buf, data, bytes);
+        *(TSKEY*)(buf + bytes) = cts;
+//        DO_UPDATE_TAG_COLUMNS(pCtx, ts);
+      }
+
       numOfElems++;
-    break;
+    }
+  } else {
+    // in case of descending order time stamp serial, which usually happens as the results of the nest query,
+    // all data needs to be check.
+    if (pResInfo->numOfRes > 0) {
+      TSKEY ts = *(TSKEY*)(buf + bytes);
+      if (ts < endKey) {
+        return TSDB_CODE_SUCCESS;
+      }
+    }
+
+    for (int32_t i = pInput->numOfRows + pInput->startRowIndex - 1; i >= pInput->startRowIndex; --i) {
+      if (pInputCol->hasNull && colDataIsNull(pInputCol, pInput->totalRows, i, pColAgg)) {
+        continue;
+      }
+
+      char* data = colDataGetData(pInputCol, i);
+
+      TSKEY cts = pCtx->ptsList ? GET_TS_DATA(pCtx, i) : 0;
+      if (pResInfo->numOfRes == 0 || *(TSKEY*)(buf + bytes) < cts) {
+        memcpy(buf, data, bytes);
+        *(TSKEY*)(buf + bytes) = cts;
+//        DO_UPDATE_TAG_COLUMNS(pCtx, ts);
+      }
+
+      numOfElems++;
+    }
   }
 
   SET_VAL(pResInfo, numOfElems, 1);
@@ -829,7 +868,7 @@ int32_t lastFunction(SqlFunctionCtx *pCtx) {
   SColumnInfoData* pInputCol = pInput->pData[0];
 
   // All null data column, return directly.
-  if (pInput->pColumnDataAgg[0]->numOfNull == pInput->totalRows) {
+  if (pInput->colDataAggIsSet && (pInput->pColumnDataAgg[0]->numOfNull == pInput->totalRows)) {
     ASSERT(pInputCol->hasNull == true);
     return 0;
   }