fix(query): support limit/offset in merge sort operator.

source/libs/executor/inc/executorimpl.h

@@ -899,6 +899,7 @@ void    doBuildResultDatablock(SOperatorInfo* pOperator, SOptrBasicInfo* pbInfo,
 int32_t handleLimitOffset(SOperatorInfo* pOperator, SLimitInfo* pLimitInfo, SSDataBlock* pBlock, bool holdDataInBuf);
 bool    hasLimitOffsetInfo(SLimitInfo* pLimitInfo);
 void    initLimitInfo(const SNode* pLimit, const SNode* pSLimit, SLimitInfo* pLimitInfo);
+void applyLimitOffset(SLimitInfo* pLimitInfo, SSDataBlock* pBlock, SExecTaskInfo* pTaskInfo, SOperatorInfo* pOperator);
 
 void doApplyFunctions(SExecTaskInfo* taskInfo, SqlFunctionCtx* pCtx, SColumnInfoData* pTimeWindowData, int32_t offset,
                       int32_t forwardStep, int32_t numOfTotal, int32_t numOfOutput);

source/libs/executor/src/scanoperator.c

@@ -355,8 +355,8 @@ static void doSetTagColumnData(STableScanInfo* pTableScanInfo, SSDataBlock* pBlo
   }
 }
 
-static void applyLimitOffset(SLimitInfo* pLimitInfo, SSDataBlock* pBlock, SExecTaskInfo* pTaskInfo,
-                             SOperatorInfo* pOperator) {
+// todo handle the slimit info
+void applyLimitOffset(SLimitInfo* pLimitInfo, SSDataBlock* pBlock, SExecTaskInfo* pTaskInfo, SOperatorInfo* pOperator) {
   SLimit* pLimit = &pLimitInfo->limit;
 
   if (pLimit->offset > 0 && pLimitInfo->remainOffset > 0) {
@@ -377,7 +377,8 @@ static void applyLimitOffset(SLimitInfo* pLimitInfo, SSDataBlock* pBlock, SExecT
 
     blockDataKeepFirstNRows(pBlock, keep);
     qDebug("output limit %"PRId64" has reached, %s", pLimit->limit, GET_TASKID(pTaskInfo));
-    setTaskStatus(pTaskInfo, TASK_COMPLETED);
+
+//    setTaskStatus(pTaskInfo, TASK_COMPLETED);
     pOperator->status = OP_EXEC_DONE;
   }
 }

source/libs/executor/src/sortoperator.c

@@ -531,7 +531,7 @@ typedef struct SMultiwayMergeOperatorInfo {
   SOptrBasicInfo binfo;
   int32_t        bufPageSize;
   uint32_t       sortBufSize;  // max buffer size for in-memory sort
-
+  SLimitInfo     limitInfo;
   SArray*        pSortInfo;
   SSortHandle*   pSortHandle;
   SColMatchInfo  matchInfo;
@@ -592,6 +592,7 @@ SSDataBlock* getMultiwaySortedBlockData(SSortHandle* pHandle, SSDataBlock* pData
 
   blockDataEnsureCapacity(p, capacity);
 
+  _retry:
   while (1) {
     STupleHandle* pTupleHandle = NULL;
     if (pInfo->groupSort) {
@@ -626,14 +627,22 @@ SSDataBlock* getMultiwaySortedBlockData(SSortHandle* pHandle, SSDataBlock* pData
     } else {
       appendOneRowToDataBlock(p, pTupleHandle);
     }
+
     if (p->info.rows >= capacity) {
       break;
     }
   }
+
   if (pInfo->groupSort) {
     pInfo->hasGroupId = false;
   }
+
   if (p->info.rows > 0) {  // todo extract method
+    applyLimitOffset(&pInfo->limitInfo, p, pTaskInfo, pOperator);
+    if (p->info.rows == 0) {
+      goto _retry;
+    }
+
     blockDataEnsureCapacity(pDataBlock, p->info.rows);
     int32_t numOfCols = taosArrayGetSize(pColMatchInfo);
     for (int32_t i = 0; i < numOfCols; ++i) {
@@ -650,9 +659,9 @@ SSDataBlock* getMultiwaySortedBlockData(SSortHandle* pHandle, SSDataBlock* pData
   }
 
   blockDataDestroy(p);
-
   qDebug("%s get sorted block, groupId:0x%" PRIx64 " rows:%d", GET_TASKID(pTaskInfo), pDataBlock->info.groupId,
          pDataBlock->info.rows);
+
   return (pDataBlock->info.rows > 0) ? pDataBlock : NULL;
 }
 
@@ -717,6 +726,7 @@ SOperatorInfo* createMultiwayMergeOperatorInfo(SOperatorInfo** downStreams, size
     goto _error;
   }
 
+  initLimitInfo(pMergePhyNode->node.pLimit, pMergePhyNode->node.pSlimit, &pInfo->limitInfo);
   pInfo->binfo.pRes = createResDataBlock(pDescNode);
   int32_t rowSize = pInfo->binfo.pRes->info.rowSize;
   ASSERT(rowSize < 100 * 1024 * 1024);
@@ -725,6 +735,10 @@ SOperatorInfo* createMultiwayMergeOperatorInfo(SOperatorInfo** downStreams, size
   int32_t numOfOutputCols = 0;
 
   code = extractColMatchInfo(pMergePhyNode->pTargets, pDescNode, &numOfOutputCols, COL_MATCH_FROM_SLOT_ID, &pInfo->matchInfo);
+  if (code != TSDB_CODE_SUCCESS) {
+    goto _error;
+  }
+
   SPhysiNode*  pChildNode = (SPhysiNode*)nodesListGetNode(pPhyNode->pChildren, 0);
   SSDataBlock* pInputBlock = createResDataBlock(pChildNode->pOutputDataBlockDesc);
   initResultSizeInfo(&pOperator->resultInfo, 1024);