fix: tag is null when table is empty

source/libs/executor/src/executil.c

@@ -2132,6 +2132,9 @@ int32_t buildGroupIdMapForAllTables(STableListInfo* pTableListInfo, SReadHandle*
     }
 
     pTableListInfo->oneTableForEachGroup = groupByTbname;
+    if (numOfTables == 1 && pTableListInfo->idInfo.tableType == TSDB_CHILD_TABLE) {
+      pTableListInfo->oneTableForEachGroup = true;
+    }
 
     if (groupSort && groupByTbname) {
       taosArraySort(pTableListInfo->pTableList, orderbyGroupIdComparFn);

source/libs/executor/src/scanoperator.c

@@ -889,14 +889,15 @@ static SSDataBlock* doGroupedTableScan(SOperatorInfo* pOperator) {
 
   if (pTableScanInfo->countState < TABLE_COUNT_STATE_END) {
     STableListInfo* pTableListInfo = pTableScanInfo->base.pTableListInfo;
-    if (pTableListInfo->oneTableForEachGroup || pTableListInfo->groupOffset) { // group by tbname, group by tag + sort
+    if (pTableListInfo->oneTableForEachGroup || pTableListInfo->groupOffset) {  // group by tbname, group by tag + sort
       if (pTableScanInfo->countState < TABLE_COUNT_STATE_PROCESSED) {
         pTableScanInfo->countState = TABLE_COUNT_STATE_PROCESSED;
         STableKeyInfo* pStart =
             (STableKeyInfo*)tableListGetInfo(pTableScanInfo->base.pTableListInfo, pTableScanInfo->tableStartIndex);
+        if (NULL == pStart) return NULL;
         return getBlockForEmptyTable(pOperator, pStart);
       }
-    } else { // group by tag + no sort
+    } else {  // group by tag + no sort
       int32_t numOfTables = tableListGetSize(pTableListInfo);
       if (pTableScanInfo->tableEndIndex + 1 >= numOfTables) {
         // get empty group, mark processed & rm from hash

source/libs/parser/src/parTranslater.c

@@ -2702,6 +2702,15 @@ static bool hasTbnameFunction(SNodeList* pPartitionByList) {
   return false;
 }
 
+static bool fromSubtable(SNode* table) {
+  if (NULL == table) return false;
+  if (table->type == QUERY_NODE_REAL_TABLE && ((SRealTableNode*)table)->pMeta &&
+      ((SRealTableNode*)table)->pMeta->tableType == TSDB_CHILD_TABLE) {
+    return true;
+  }
+  return false;
+}
+
 static EDealRes doCheckExprForGroupBy(SNode** pNode, void* pContext) {
   STranslateContext* pCxt = (STranslateContext*)pContext;
   SSelectStmt*       pSelect = (SSelectStmt*)pCxt->pCurrStmt;
@@ -2795,15 +2804,18 @@ static EDealRes doCheckAggColCoexist(SNode** pNode, void* pContext) {
     return DEAL_RES_IGNORE_CHILD;
   }
   SNode* pPartKey = NULL;
-  bool   partionByTbname = hasTbnameFunction(((SSelectStmt*)pCxt->pTranslateCxt->pCurrStmt)->pPartitionByList);
+  bool   partionByTbname = false;
+  if (fromSubtable(((SSelectStmt*)pCxt->pTranslateCxt->pCurrStmt)->pFromTable) ||
+      hasTbnameFunction(((SSelectStmt*)pCxt->pTranslateCxt->pCurrStmt)->pPartitionByList)) {
+    partionByTbname = true;
+  }
   FOREACH(pPartKey, ((SSelectStmt*)pCxt->pTranslateCxt->pCurrStmt)->pPartitionByList) {
     if (nodesEqualNode(pPartKey, *pNode)) {
       return rewriteExprToGroupKeyFunc(pCxt->pTranslateCxt, pNode);
     }
-    if (partionByTbname && QUERY_NODE_COLUMN == nodeType(*pNode) &&
+  }
-        ((SColumnNode*)*pNode)->colType == COLUMN_TYPE_TAG) {
+  if (partionByTbname && QUERY_NODE_COLUMN == nodeType(*pNode) && ((SColumnNode*)*pNode)->colType == COLUMN_TYPE_TAG) {
-      return rewriteExprToGroupKeyFunc(pCxt->pTranslateCxt, pNode);
+    return rewriteExprToGroupKeyFunc(pCxt->pTranslateCxt, pNode);
-    }
   }
   if (isScanPseudoColumnFunc(*pNode) || QUERY_NODE_COLUMN == nodeType(*pNode)) {
     pCxt->existCol = true;

source/libs/planner/src/planLogicCreater.c

@@ -494,6 +494,9 @@ static int32_t createScanLogicNode(SLogicPlanContext* pCxt, SSelectStmt* pSelect
     } else if (pSelect->pPartitionByList) {
       isCountByTag = !keysHasCol(pSelect->pPartitionByList);
     }
+    if (pScan->tableType == TSDB_CHILD_TABLE) {
+      isCountByTag = true;
+    }
   }
   pScan->isCountByTag = isCountByTag;