fix(query): handle the multi-group limit/offset in table group merge scan/ multiway-merge executor.

source/libs/executor/inc/executorimpl.h

@@ -705,7 +705,8 @@ void doBuildResultDatablock(SOperatorInfo* pOperator, SOptrBasicInfo* pbInfo, SG
 
 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 resetLimitInfoForNextGroup(SLimitInfo* pLimitInfo);
+bool applyLimitOffset(SLimitInfo* pLimitInfo, SSDataBlock* pBlock, SExecTaskInfo* pTaskInfo, SOperatorInfo* pOperator);
 
 void applyAggFunctionOnPartialTuples(SExecTaskInfo* taskInfo, SqlFunctionCtx* pCtx, SColumnInfoData* pTimeWindowData,
                                      int32_t offset, int32_t forwardStep, int32_t numOfTotal, int32_t numOfOutput);

source/libs/executor/src/exchangeoperator.c

@@ -738,9 +738,7 @@ int32_t handleLimitOffset(SOperatorInfo* pOperator, SLimitInfo* pLimitInfo, SSDa
     }
 
     // reset the value for a new group data
-    pLimitInfo->numOfOutputRows = 0;
+    resetLimitInfoForNextGroup(pLimitInfo);
-    pLimitInfo->remainOffset = pLimitInfo->limit.offset;
-
     // existing rows that belongs to previous group.
     if (pBlock->info.rows > 0) {
       return PROJECT_RETRIEVE_DONE;
@@ -766,7 +764,12 @@ int32_t handleLimitOffset(SOperatorInfo* pOperator, SLimitInfo* pLimitInfo, SSDa
     int32_t keepRows = (int32_t)(pLimitInfo->limit.limit - pLimitInfo->numOfOutputRows);
     blockDataKeepFirstNRows(pBlock, keepRows);
     if (pLimitInfo->slimit.limit > 0 && pLimitInfo->slimit.limit <= pLimitInfo->numOfOutputGroups) {
-      pOperator->status = OP_EXEC_DONE;
+      setOperatorCompleted(pOperator);
+    } else {
+      // current group limitation is reached, and future blocks of this group need to be discarded.
+      if (pBlock->info.rows == 0) {
+        return PROJECT_RETRIEVE_CONTINUE;
+      }
     }
 
     return PROJECT_RETRIEVE_DONE;

source/libs/executor/src/executil.c

@@ -1759,6 +1759,11 @@ void initLimitInfo(const SNode* pLimit, const SNode* pSLimit, SLimitInfo* pLimit
   pLimitInfo->remainGroupOffset = slimit.offset;
 }
 
+void resetLimitInfoForNextGroup(SLimitInfo* pLimitInfo) {
+  pLimitInfo->numOfOutputRows = 0;
+  pLimitInfo->remainOffset = pLimitInfo->limit.offset;
+}
+
 uint64_t tableListGetSize(const STableListInfo* pTableList) {
   ASSERT(taosArrayGetSize(pTableList->pTableList) == taosHashGetSize(pTableList->map));
   return taosArrayGetSize(pTableList->pTableList);

source/libs/executor/src/projectoperator.c

@@ -175,8 +175,7 @@ static int32_t setInfoForNewGroup(SSDataBlock* pBlock, SLimitInfo* pLimitInfo, S
 
     // reset the value for a new group data
     // existing rows that belongs to previous group.
-    pLimitInfo->numOfOutputRows = 0;
+    resetLimitInfoForNextGroup(pLimitInfo);
-    pLimitInfo->remainOffset = pLimitInfo->limit.offset;
   }
 
   return PROJECT_RETRIEVE_DONE;
@@ -200,10 +199,18 @@ static int32_t doIngroupLimitOffset(SLimitInfo* pLimitInfo, uint64_t groupId, SS
   if (pLimitInfo->limit.limit >= 0 && pLimitInfo->numOfOutputRows + pBlock->info.rows >= pLimitInfo->limit.limit) {
     int32_t keepRows = (int32_t)(pLimitInfo->limit.limit - pLimitInfo->numOfOutputRows);
     blockDataKeepFirstNRows(pBlock, keepRows);
+
     // TODO: optimize it later when partition by + limit
+    // all retrieved requirement has been fulfilled, let's finish this
     if ((pLimitInfo->slimit.limit == -1 && pLimitInfo->currentGroupId == 0) ||
         (pLimitInfo->slimit.limit > 0 && pLimitInfo->slimit.limit <= pLimitInfo->numOfOutputGroups)) {
       setOperatorCompleted(pOperator);
+    } else {
+      // Even current group is done, there may be many vgroups remain existed, and we need to continue to retrieve data
+      // from next group. So let's continue this retrieve process
+      if (keepRows == 0) {
+        return PROJECT_RETRIEVE_CONTINUE;
+      }
     }
   }
 
@@ -357,7 +364,6 @@ SSDataBlock* doProjectOperation(SOperatorInfo* pOperator) {
     pOperator->cost.openCost = (taosGetTimestampUs() - st) / 1000.0;
   }
 
-  // printDataBlock1(p, "project");
   return (p->info.rows > 0) ? p : NULL;
 }
 

source/libs/executor/src/scanoperator.c

@@ -257,7 +257,7 @@ static void doSetTagColumnData(STableScanBase* pTableScanInfo, SSDataBlock* pBlo
 }
 
 // todo handle the slimit info
-void applyLimitOffset(SLimitInfo* pLimitInfo, SSDataBlock* pBlock, SExecTaskInfo* pTaskInfo, SOperatorInfo* pOperator) {
+bool applyLimitOffset(SLimitInfo* pLimitInfo, SSDataBlock* pBlock, SExecTaskInfo* pTaskInfo, SOperatorInfo* pOperator) {
   SLimit*     pLimit = &pLimitInfo->limit;
   const char* id = GET_TASKID(pTaskInfo);
 
@@ -266,6 +266,7 @@ void applyLimitOffset(SLimitInfo* pLimitInfo, SSDataBlock* pBlock, SExecTaskInfo
       pLimitInfo->remainOffset -= pBlock->info.rows;
       blockDataEmpty(pBlock);
       qDebug("current block ignore due to offset, current:%" PRId64 ", %s", pLimitInfo->remainOffset, id);
+      return false;
     } else {
       blockDataTrimFirstNRows(pBlock, pLimitInfo->remainOffset);
       pLimitInfo->remainOffset = 0;
@@ -274,13 +275,14 @@ void applyLimitOffset(SLimitInfo* pLimitInfo, SSDataBlock* pBlock, SExecTaskInfo
 
   if (pLimit->limit != -1 && pLimit->limit <= (pLimitInfo->numOfOutputRows + pBlock->info.rows)) {
     // limit the output rows
-    int32_t overflowRows = pLimitInfo->numOfOutputRows + pBlock->info.rows - pLimit->limit;
+    int32_t keep = (int32_t)(pLimit->limit - pLimitInfo->numOfOutputRows);
-    int32_t keep = pBlock->info.rows - overflowRows;
 
     blockDataKeepFirstNRows(pBlock, keep);
     qDebug("output limit %" PRId64 " has reached, %s", pLimit->limit, id);
-    pOperator->status = OP_EXEC_DONE;
+    return true;
   }
+
+  return false;
 }
 
 static int32_t loadDataBlock(SOperatorInfo* pOperator, STableScanBase* pTableScanInfo, SSDataBlock* pBlock,
@@ -391,7 +393,10 @@ static int32_t loadDataBlock(SOperatorInfo* pOperator, STableScanBase* pTableSca
     }
   }
 
-  applyLimitOffset(&pTableScanInfo->limitInfo, pBlock, pTaskInfo, pOperator);
+  bool limitReached = applyLimitOffset(&pTableScanInfo->limitInfo, pBlock, pTaskInfo, pOperator);
+  if (limitReached) { // set operator flag is done
+    setOperatorCompleted(pOperator);
+  }
 
   pCost->totalRows += pBlock->info.rows;
   pTableScanInfo->limitInfo.numOfOutputRows = pCost->totalRows;
@@ -768,8 +773,7 @@ static SSDataBlock* doTableScan(SOperatorInfo* pOperator) {
 
     // reset value for the next group data output
     pOperator->status = OP_OPENED;
-    pInfo->base.limitInfo.numOfOutputRows = 0;
+    resetLimitInfoForNextGroup(&pInfo->base.limitInfo);
-    pInfo->base.limitInfo.remainOffset = pInfo->base.limitInfo.limit.offset;
 
     int32_t        num = 0;
     STableKeyInfo* pList = NULL;
@@ -2685,9 +2689,12 @@ int32_t stopGroupTableMergeScan(SOperatorInfo* pOperator) {
   taosArrayDestroy(pInfo->queryConds);
   pInfo->queryConds = NULL;
 
+  resetLimitInfoForNextGroup(&pInfo->limitInfo);
   return TSDB_CODE_SUCCESS;
 }
 
+// all data produced by this function only belongs to one group
+// slimit/soffset does not need to be concerned here, since this function only deal with data within one group.
 SSDataBlock* getSortedTableMergeScanBlockData(SSortHandle* pHandle, SSDataBlock* pResBlock, int32_t capacity,
                                               SOperatorInfo* pOperator) {
   STableMergeScanInfo* pInfo = pOperator->info;
@@ -2707,10 +2714,12 @@ SSDataBlock* getSortedTableMergeScanBlockData(SSortHandle* pHandle, SSDataBlock*
     }
   }
 
-  qDebug("%s get sorted row blocks, rows:%d", GET_TASKID(pTaskInfo), pResBlock->info.rows);
   applyLimitOffset(&pInfo->limitInfo, pResBlock, pTaskInfo, pOperator);
   pInfo->limitInfo.numOfOutputRows += pResBlock->info.rows;
 
+  qDebug("%s get sorted row block, rows:%d, limit:%"PRId64, GET_TASKID(pTaskInfo), pResBlock->info.rows,
+      pInfo->limitInfo.numOfOutputRows);
+
   return (pResBlock->info.rows > 0) ? pResBlock : NULL;
 }
 
@@ -2749,11 +2758,13 @@ SSDataBlock* doTableMergeScan(SOperatorInfo* pOperator) {
       pOperator->resultInfo.totalRows += pBlock->info.rows;
       return pBlock;
     } else {
+      // Data of this group are all dumped, let's try the next group
       stopGroupTableMergeScan(pOperator);
       if (pInfo->tableEndIndex >= tableListSize - 1) {
         setOperatorCompleted(pOperator);
         break;
       }
+
       pInfo->tableStartIndex = pInfo->tableEndIndex + 1;
       pInfo->groupId = tableListGetInfo(pTaskInfo->pTableInfoList, pInfo->tableStartIndex)->groupId;
       startGroupTableMergeScan(pOperator);

source/libs/executor/src/sortoperator.c

@@ -680,13 +680,15 @@ SSDataBlock* getMultiwaySortedBlockData(SSortHandle* pHandle, SSDataBlock* pData
       break;
     }
 
-    if (p->info.rows > 0) {
+    bool limitReached = applyLimitOffset(&pInfo->limitInfo, p, pTaskInfo, pOperator);
-      applyLimitOffset(&pInfo->limitInfo, p, pTaskInfo, pOperator);
+    if (limitReached) {
+      resetLimitInfoForNextGroup(&pInfo->limitInfo);
+    }
+
     if (p->info.rows > 0) {
       break;
     }
   }
-  }
 
   if (p->info.rows > 0) {
     int32_t numOfCols = taosArrayGetSize(pColMatchInfo);
@@ -698,7 +700,6 @@ SSDataBlock* getMultiwaySortedBlockData(SSortHandle* pHandle, SSDataBlock* pData
       colDataAssign(pDst, pSrc, p->info.rows, &pDataBlock->info);
     }
 
-    pInfo->limitInfo.numOfOutputRows += p->info.rows;
     pDataBlock->info.rows = p->info.rows;
     pDataBlock->info.id.groupId = pInfo->groupId;
     pDataBlock->info.dataLoad = 1;