[td-11818] Update the physical plan in case of the subscribe processing.

source/libs/planner/src/physicalPlan.c

@@ -296,6 +296,7 @@ static SPhyNode* createTableScanNode(SPlanContext* pCxt, SQueryPlanNode* pPlanNo
   if (needMultiNodeScan(pTable)) {
     return createExchangeNode(pCxt, pPlanNode, splitSubplanByTable(pCxt, pPlanNode, pTable));
   }
+
   return createSingleTableScanNode(pPlanNode, pTable, pCxt->pCurrentSubplan);
 }
 
@@ -386,6 +387,33 @@ static void createSubplanByLevel(SPlanContext* pCxt, SQueryPlanNode* pRoot) {
   // todo deal subquery
 }
 
+static void postCreateDag(SQueryPlanNode* pQueryNode, SQueryDag* pDag, SArray* pNodeList) {
+  // The exchange operator is not necessary, in case of the stream scan.
+  // Here we need to remove it from the DAG.
+  if (pQueryNode->info.type == QNODE_STREAMSCAN) {
+    SArray* pRootLevel = taosArrayGetP(pDag->pSubplans, 0);
+    SSubplan *pSubplan = taosArrayGetP(pRootLevel, 0);
+
+    if (pSubplan->pNode->info.type == OP_Exchange) {
+      ASSERT(taosArrayGetSize(pRootLevel) == 1);
+
+      taosArrayRemove(pDag->pSubplans, 0);
+      // And then update the number of the subplans.
+      pDag->numOfSubplans -= 1;
+    }
+  } else {
+    // Traverse the dag again to acquire the execution node.
+    if (pNodeList != NULL) {
+      SArray** pSubLevel = taosArrayGetLast(pDag->pSubplans);
+      size_t   num = taosArrayGetSize(*pSubLevel);
+      for (int32_t j = 0; j < num; ++j) {
+        SSubplan* pPlan = taosArrayGetP(*pSubLevel, j);
+        taosArrayPush(pNodeList, &pPlan->execNode);
+      }
+    }
+  }
+}
+
 int32_t createDag(SQueryPlanNode* pQueryNode, struct SCatalog* pCatalog, SQueryDag** pDag, SArray* pNodeList, uint64_t requestId) {
   TRY(TSDB_MAX_TAG_CONDITIONS) {
     SPlanContext context = {
@@ -407,16 +435,7 @@ int32_t createDag(SQueryPlanNode* pQueryNode, struct SCatalog* pCatalog, SQueryD
     return TSDB_CODE_FAILED;
   } END_TRY
 
-  // traverse the dag again to acquire the execution node.
-  if (pNodeList != NULL) {
-    SArray** pSubLevel = taosArrayGetLast((*pDag)->pSubplans);
-    size_t  num = taosArrayGetSize(*pSubLevel);
-    for (int32_t j = 0; j < num; ++j) {
-      SSubplan* pPlan = taosArrayGetP(*pSubLevel, j);
-      taosArrayPush(pNodeList, &pPlan->execNode);
-    }
-  }
-
+  postCreateDag(pQueryNode, *pDag, pNodeList);
   return TSDB_CODE_SUCCESS;
 }