diff --git a/source/dnode/mnode/impl/inc/mndDef.h b/source/dnode/mnode/impl/inc/mndDef.h
index 7d707f4cbaa4021223e8e8ed59342453b8b87584..82b714e6eb6e3a29cc3ea16d1fb4d0c1bd9d6a6d 100644
--- a/source/dnode/mnode/impl/inc/mndDef.h
+++ b/source/dnode/mnode/impl/inc/mndDef.h
@@ -663,9 +663,10 @@ typedef struct {
   char    targetDb[TSDB_DB_FNAME_LEN];
   char    targetSTbName[TSDB_TABLE_FNAME_LEN];
   int64_t targetStbUid;
-  int32_t fixedSinkVgId;  // 0 for shuffle
+
   // fixedSinkVg is not applicable for encode and decode
   SVgObj fixedSinkVg;
+  int32_t fixedSinkVgId;  // 0 for shuffle
 
   // transformation
   char*          sql;
diff --git a/source/dnode/mnode/impl/src/mndScheduler.c b/source/dnode/mnode/impl/src/mndScheduler.c
index 18f10e92f9e10aa326e17396074692099f27be26..b68565b14668f99c5e881be9ce98ecdacaab0f4e 100644
--- a/source/dnode/mnode/impl/src/mndScheduler.c
+++ b/source/dnode/mnode/impl/src/mndScheduler.c
@@ -14,18 +14,8 @@
  */
 
 #include "mndScheduler.h"
-#include "mndConsumer.h"
 #include "mndDb.h"
-#include "mndDnode.h"
-#include "mndMnode.h"
-#include "mndShow.h"
 #include "mndSnode.h"
-#include "mndStb.h"
-#include "mndStream.h"
-#include "mndSubscribe.h"
-#include "mndTopic.h"
-#include "mndTrans.h"
-#include "mndUser.h"
 #include "mndVgroup.h"
 #include "parser.h"
 #include "tcompare.h"
@@ -34,7 +24,10 @@
 
 extern bool tsDeployOnSnode;
 
-static int32_t mndAddTaskToTaskSet(SArray* pArray, SStreamTask* pTask) {
+static int32_t mndAddSinkTaskToStream(SStreamObj* pStream, SMnode* pMnode, int32_t vgId, SVgObj* pVgroup);
+static void setFixedDownstreamEpInfo(SStreamTask* pDstTask, const SStreamTask* pTask);
+
+static int32_t mndAddToTaskset(SArray* pArray, SStreamTask* pTask) {
   int32_t childId = taosArrayGetSize(pArray);
   pTask->selfChildId = childId;
   taosArrayPush(pArray, &pTask);
@@ -97,7 +90,7 @@ END:
   return terrno;
 }
 
-int32_t mndAddSinkToTask(SMnode* pMnode, SStreamObj* pStream, SStreamTask* pTask) {
+int32_t mndSetSinkTaskInfo(SStreamObj* pStream, SStreamTask* pTask) {
   if (pStream->smaId != 0) {
     pTask->outputType = TASK_OUTPUT__SMA;
     pTask->smaSink.smaId = pStream->smaId;
@@ -106,18 +99,23 @@ int32_t mndAddSinkToTask(SMnode* pMnode, SStreamObj* pStream, SStreamTask* pTask
     pTask->tbSink.stbUid = pStream->targetStbUid;
     memcpy(pTask->tbSink.stbFullName, pStream->targetSTbName, TSDB_TABLE_FNAME_LEN);
     pTask->tbSink.pSchemaWrapper = tCloneSSchemaWrapper(&pStream->outputSchema);
+    if (pTask->tbSink.pSchemaWrapper == NULL) {
+      return TSDB_CODE_OUT_OF_MEMORY;
+    }
   }
+
   return 0;
 }
 
 #define SINK_NODE_LEVEL (0)
 
-int32_t mndAddDispatcherToInnerTask(SMnode* pMnode, SStreamObj* pStream, SStreamTask* pTask) {
+int32_t mndAddDispatcherForInnerTask(SMnode* pMnode, SStreamObj* pStream, SStreamTask* pTask) {
   bool isShuffle = false;
 
   if (pStream->fixedSinkVgId == 0) {
     SDbObj* pDb = mndAcquireDb(pMnode, pStream->targetDb);
     if (pDb != NULL && pDb->cfg.numOfVgroups > 1) {
+
       isShuffle = true;
       pTask->outputType = TASK_OUTPUT__SHUFFLE_DISPATCH;
       pTask->dispatchMsgType = TDMT_STREAM_TASK_DISPATCH;
@@ -129,19 +127,19 @@ int32_t mndAddDispatcherToInnerTask(SMnode* pMnode, SStreamObj* pStream, SStream
     sdbRelease(pMnode->pSdb, pDb);
   }
 
+  SArray* pSinkNodeList = taosArrayGetP(pStream->tasks, SINK_NODE_LEVEL);
+  int32_t numOfSinkNodes = taosArrayGetSize(pSinkNodeList);
+
   if (isShuffle) {
     memcpy(pTask->shuffleDispatcher.stbFullName, pStream->targetSTbName, TSDB_TABLE_FNAME_LEN);
     SArray* pVgs = pTask->shuffleDispatcher.dbInfo.pVgroupInfos;
 
-    SArray* pSinkNodes = taosArrayGetP(pStream->tasks, SINK_NODE_LEVEL);
-    int32_t numOfSinkNodes = taosArrayGetSize(pSinkNodes);
-
     int32_t numOfVgroups = taosArrayGetSize(pVgs);
     for (int32_t i = 0; i < numOfVgroups; i++) {
       SVgroupInfo* pVgInfo = taosArrayGet(pVgs, i);
 
       for (int32_t j = 0; j < numOfSinkNodes; j++) {
-        SStreamTask* pSinkTask = taosArrayGetP(pSinkNodes, j);
+        SStreamTask* pSinkTask = taosArrayGetP(pSinkNodeList, j);
         if (pSinkTask->nodeId == pVgInfo->vgId) {
           pVgInfo->taskId = pSinkTask->id.taskId;
           break;
@@ -149,17 +147,8 @@ int32_t mndAddDispatcherToInnerTask(SMnode* pMnode, SStreamObj* pStream, SStream
       }
     }
   } else {
-    pTask->outputType = TASK_OUTPUT__FIXED_DISPATCH;
-    pTask->dispatchMsgType = TDMT_STREAM_TASK_DISPATCH;
-    SArray* pSinkNodeList = taosArrayGetP(pStream->tasks, SINK_NODE_LEVEL);
-
-    // one sink only
-    SStreamTask* lastLevelTask = taosArrayGetP(pSinkNodeList, 0);
-    STaskDispatcherFixedEp* pDispatcher = &pTask->fixedEpDispatcher;
-
-    pDispatcher->taskId = lastLevelTask->id.taskId;
-    pDispatcher->nodeId = lastLevelTask->nodeId;
-    pDispatcher->epSet = lastLevelTask->epSet;
+    SStreamTask* pOneSinkTask = taosArrayGetP(pSinkNodeList, 0);
+    setFixedDownstreamEpInfo(pTask, pOneSinkTask);
   }
 
   return 0;
@@ -224,7 +213,6 @@ SVgObj* mndSchedFetchOneVg(SMnode* pMnode, int64_t dbUid) {
 int32_t mndAddShuffleSinkTasksToStream(SMnode* pMnode, SStreamObj* pStream) {
   SSdb*   pSdb = pMnode->pSdb;
   void*   pIter = NULL;
-  SArray* pTaskList = taosArrayGetP(pStream->tasks, 0);
 
   while (1) {
     SVgObj* pVgroup = NULL;
@@ -238,73 +226,97 @@ int32_t mndAddShuffleSinkTasksToStream(SMnode* pMnode, SStreamObj* pStream) {
       continue;
     }
 
-    SStreamTask* pTask = tNewStreamTask(pStream->uid, TASK_LEVEL__SINK, pStream->fillHistory);
-    if (pTask == NULL) {
-      sdbRelease(pSdb, pVgroup);
-      terrno = TSDB_CODE_OUT_OF_MEMORY;
-      return -1;
-    }
-
-    mndAddTaskToTaskSet(pTaskList, pTask);
-    pTask->nodeId = pVgroup->vgId;
-    pTask->epSet = mndGetVgroupEpset(pMnode, pVgroup);
-
-    // sink
-    if (pStream->smaId != 0) {
-      pTask->outputType = TASK_OUTPUT__SMA;
-      pTask->smaSink.smaId = pStream->smaId;
-    } else {
-      pTask->outputType = TASK_OUTPUT__TABLE;
-      pTask->tbSink.stbUid = pStream->targetStbUid;
-      memcpy(pTask->tbSink.stbFullName, pStream->targetSTbName, TSDB_TABLE_FNAME_LEN);
-      pTask->tbSink.pSchemaWrapper = tCloneSSchemaWrapper(&pStream->outputSchema);
-      if (pTask->tbSink.pSchemaWrapper == NULL) {
-        terrno = TSDB_CODE_OUT_OF_MEMORY;
-        return -1;
-      }
-    }
-
+    mndAddSinkTaskToStream(pStream, pMnode, pVgroup->vgId, pVgroup);
     sdbRelease(pSdb, pVgroup);
   }
+
   return 0;
 }
 
-int32_t mndAddFixedSinkTaskToStream(SMnode* pMnode, SStreamObj* pStream) {
-  SArray*      tasks = taosArrayGetP(pStream->tasks, 0);
+int32_t mndAddSinkTaskToStream(SStreamObj* pStream, SMnode* pMnode, int32_t vgId, SVgObj* pVgroup) {
+  SArray* pTaskList = taosArrayGetP(pStream->tasks, SINK_NODE_LEVEL);
+
   SStreamTask* pTask = tNewStreamTask(pStream->uid, TASK_LEVEL__SINK, pStream->fillHistory);
   if (pTask == NULL) {
     terrno = TSDB_CODE_OUT_OF_MEMORY;
     return -1;
   }
 
-  mndAddTaskToTaskSet(tasks, pTask);
-  pTask->nodeId = pStream->fixedSinkVgId;
+  mndAddToTaskset(pTaskList, pTask);
 
-#if 0
-  SVgObj* pVgroup = mndAcquireVgroup(pMnode, pStream->fixedSinkVgId);
-  if (pVgroup == NULL) {
-    return -1;
-  }
+  pTask->nodeId = vgId;
   pTask->epSet = mndGetVgroupEpset(pMnode, pVgroup);
-#endif
+  mndSetSinkTaskInfo(pStream, pTask);
+  return 0;
+}
 
-  pTask->epSet = mndGetVgroupEpset(pMnode, &pStream->fixedSinkVg);
+static int32_t mndScheduleFillHistoryStreamTask(SMnode* pMnode, SStreamObj* pStream) {
+  return 0;
+}
 
-  // sink
-  if (pStream->smaId != 0) {
-    pTask->outputType = TASK_OUTPUT__SMA;
-    pTask->smaSink.smaId = pStream->smaId;
+static int32_t addSourceStreamTask(SMnode* pMnode, SVgObj* pVgroup, SArray* pTaskList, SStreamObj* pStream,
+                                   SSubplan* plan, uint64_t uid, int8_t taskLevel, int8_t fillHistory,
+                                   bool hasExtraSink) {
+  SStreamTask* pTask = tNewStreamTask(uid, taskLevel, fillHistory);
+  if (pTask == NULL) {
+    return terrno;
+  }
+
+  mndAddToTaskset(pTaskList, pTask);
+  pTask->triggerParam = pStream->triggerParam; // trigger
+
+  // sink or dispatch
+  if (hasExtraSink) {
+    mndAddDispatcherForInnerTask(pMnode, pStream, pTask);
   } else {
-    pTask->outputType = TASK_OUTPUT__TABLE;
-    pTask->tbSink.stbUid = pStream->targetStbUid;
-    memcpy(pTask->tbSink.stbFullName, pStream->targetSTbName, TSDB_TABLE_FNAME_LEN);
-    pTask->tbSink.pSchemaWrapper = tCloneSSchemaWrapper(&pStream->outputSchema);
+    mndSetSinkTaskInfo(pStream, pTask);
   }
 
-  return 0;
+  if (mndAssignStreamTaskToVgroup(pMnode, pTask, plan, pVgroup) < 0) {
+    return terrno;
+  }
+
+  return TSDB_CODE_SUCCESS;
 }
 
+static SStreamChildEpInfo* createStreamTaskEpInfo(SStreamTask* pTask) {
+  SStreamChildEpInfo* pEpInfo = taosMemoryMalloc(sizeof(SStreamChildEpInfo));
+  if (pEpInfo == NULL) {
+    terrno = TSDB_CODE_OUT_OF_MEMORY;
+    return NULL;
+  }
+
+  pEpInfo->childId = pTask->selfChildId;
+  pEpInfo->epSet = pTask->epSet;
+  pEpInfo->nodeId = pTask->nodeId;
+  pEpInfo->taskId = pTask->id.taskId;
+
+  return pEpInfo;
+}
+
+void setFixedDownstreamEpInfo(SStreamTask* pDstTask, const SStreamTask* pTask) {
+  STaskDispatcherFixedEp* pDispatcher = &pDstTask->fixedEpDispatcher;
+  pDispatcher->taskId = pTask->id.taskId;
+  pDispatcher->nodeId = pTask->nodeId;
+  pDispatcher->epSet = pTask->epSet;
 
+  pDstTask->outputType = TASK_OUTPUT__FIXED_DISPATCH;
+  pDstTask->dispatchMsgType = TDMT_STREAM_TASK_DISPATCH;
+}
+
+int32_t appendToUpstream(SStreamTask* pTask, SStreamTask* pUpstream) {
+  SStreamChildEpInfo* pEpInfo = createStreamTaskEpInfo(pTask);
+  if (pEpInfo == NULL) {
+    return TSDB_CODE_OUT_OF_MEMORY;
+  }
+
+  if(pUpstream->childEpInfo == NULL) {
+    pUpstream->childEpInfo = taosArrayInit(4, POINTER_BYTES);
+  }
+  
+  taosArrayPush(pUpstream->childEpInfo, &pEpInfo);
+  return TSDB_CODE_SUCCESS;
+}
 
 int32_t mndScheduleStream(SMnode* pMnode, SStreamObj* pStream) {
   SSdb* pSdb = pMnode->pSdb;
@@ -341,7 +353,7 @@ int32_t mndScheduleStream(SMnode* pMnode, SStreamObj* pStream) {
         return -1;
       }
     } else {
-      if (mndAddFixedSinkTaskToStream(pMnode, pStream) < 0) {
+      if (mndAddSinkTaskToStream(pStream, pMnode, pStream->fixedSinkVgId, &pStream->fixedSinkVg) < 0) {
         // TODO free
         return -1;
       }
@@ -354,7 +366,7 @@ int32_t mndScheduleStream(SMnode* pMnode, SStreamObj* pStream) {
     SStreamTask* pInnerTask;
     // inner level
     {
-      SArray* taskInnerLevel = taosArrayInit(0, sizeof(void*));
+      SArray* taskInnerLevel = taosArrayInit(0, POINTER_BYTES);
       taosArrayPush(pStream->tasks, &taskInnerLevel);
 
       SNodeListNode* inner = (SNodeListNode*)nodesListGetNode(pPlan->pSubplans, 0);
@@ -371,12 +383,11 @@ int32_t mndScheduleStream(SMnode* pMnode, SStreamObj* pStream) {
         return -1;
       }
 
-      mndAddTaskToTaskSet(taskInnerLevel, pInnerTask);
-      pInnerTask->childEpInfo = taosArrayInit(0, POINTER_BYTES);
+      mndAddToTaskset(taskInnerLevel, pInnerTask);
       pInnerTask->triggerParam = pStream->triggerParam;      // trigger
 
       // dispatch
-      if (mndAddDispatcherToInnerTask(pMnode, pStream, pInnerTask) < 0) {
+      if (mndAddDispatcherForInnerTask(pMnode, pStream, pInnerTask) < 0) {
         qDestroyQueryPlan(pPlan);
         return -1;
       }
@@ -411,7 +422,7 @@ int32_t mndScheduleStream(SMnode* pMnode, SStreamObj* pStream) {
     }
 
     // source level
-    SArray* taskSourceLevel = taosArrayInit(0, sizeof(void*));
+    SArray* taskSourceLevel = taosArrayInit(0, POINTER_BYTES);
     taosArrayPush(pStream->tasks, &taskSourceLevel);
 
     SNodeListNode* inner = (SNodeListNode*)nodesListGetNode(pPlan->pSubplans, 1);
@@ -425,7 +436,10 @@ int32_t mndScheduleStream(SMnode* pMnode, SStreamObj* pStream) {
     while (1) {
       SVgObj* pVgroup;
       pIter = sdbFetch(pSdb, SDB_VGROUP, pIter, (void**)&pVgroup);
-      if (pIter == NULL) break;
+      if (pIter == NULL) {
+        break;
+      }
+
       if (!mndVgroupInDb(pVgroup, pStream->sourceDbUid)) {
         sdbRelease(pSdb, pVgroup);
         continue;
@@ -439,15 +453,11 @@ int32_t mndScheduleStream(SMnode* pMnode, SStreamObj* pStream) {
         return -1;
       }
 
-      mndAddTaskToTaskSet(taskSourceLevel, pTask);
-      pTask->triggerParam = 0;
-
-      pTask->dispatchMsgType = TDMT_STREAM_TASK_DISPATCH; // add fixed vg dispatch
-      pTask->outputType = TASK_OUTPUT__FIXED_DISPATCH;
+      mndAddToTaskset(taskSourceLevel, pTask);
 
-      pTask->fixedEpDispatcher.taskId = pInnerTask->id.taskId;
-      pTask->fixedEpDispatcher.nodeId = pInnerTask->nodeId;
-      pTask->fixedEpDispatcher.epSet = pInnerTask->epSet;
+      // all the source tasks dispatch result to a single agg node.
+      setFixedDownstreamEpInfo(pTask, pInnerTask);
+      pTask->triggerParam = 0;
 
       if (mndAssignStreamTaskToVgroup(pMnode, pTask, plan, pVgroup) < 0) {
         sdbRelease(pSdb, pVgroup);
@@ -455,25 +465,19 @@ int32_t mndScheduleStream(SMnode* pMnode, SStreamObj* pStream) {
         return -1;
       }
 
-      SStreamChildEpInfo* pEpInfo = taosMemoryMalloc(sizeof(SStreamChildEpInfo));
-      if (pEpInfo == NULL) {
-        terrno = TSDB_CODE_OUT_OF_MEMORY;
-        sdbRelease(pSdb, pVgroup);
+      int32_t code = appendToUpstream(pTask, pInnerTask);
+      sdbRelease(pSdb, pVgroup);
+
+      if (code != TSDB_CODE_SUCCESS) {
+        terrno = code;
         qDestroyQueryPlan(pPlan);
         return -1;
       }
-
-      pEpInfo->childId = pTask->selfChildId;
-      pEpInfo->epSet = pTask->epSet;
-      pEpInfo->nodeId = pTask->nodeId;
-      pEpInfo->taskId = pTask->id.taskId;
-      taosArrayPush(pInnerTask->childEpInfo, &pEpInfo);
-      sdbRelease(pSdb, pVgroup);
     }
   } else if (planTotLevel == 1) {
     // create exec stream task, since only one level, the exec task is also the source task
-    SArray* taskOneLevel = taosArrayInit(0, POINTER_BYTES);
-    taosArrayPush(pStream->tasks, &taskOneLevel);
+    SArray* pTaskList = taosArrayInit(0, POINTER_BYTES);
+    taosArrayPush(pStream->tasks, &pTaskList);
 
     SNodeListNode* inner = (SNodeListNode*)nodesListGetNode(pPlan->pSubplans, 0);
     if (LIST_LENGTH(inner->pNodeList) != 1) {
@@ -501,30 +505,13 @@ int32_t mndScheduleStream(SMnode* pMnode, SStreamObj* pStream) {
       }
 
       // new stream task
-      SStreamTask* pTask = tNewStreamTask(pStream->uid, TASK_LEVEL__SOURCE, pStream->fillHistory);
-      if (pTask == NULL) {
-        sdbRelease(pSdb, pVgroup);
-        qDestroyQueryPlan(pPlan);
-        return -1;
-      }
-
-      mndAddTaskToTaskSet(taskOneLevel, pTask);
-      pTask->triggerParam = pStream->triggerParam; // trigger
-
-      // sink or dispatch
-      if (hasExtraSink) {
-        mndAddDispatcherToInnerTask(pMnode, pStream, pTask);
-      } else {
-        mndAddSinkToTask(pMnode, pStream, pTask);
-      }
+      int32_t code = addSourceStreamTask(pMnode, pVgroup, pTaskList, pStream, plan, pStream->uid, TASK_LEVEL__SOURCE, pStream->fillHistory, hasExtraSink);
+      sdbRelease(pSdb, pVgroup);
 
-      if (mndAssignStreamTaskToVgroup(pMnode, pTask, plan, pVgroup) < 0) {
-        sdbRelease(pSdb, pVgroup);
+      if (code != TSDB_CODE_SUCCESS) {
         qDestroyQueryPlan(pPlan);
         return -1;
       }
-
-      sdbRelease(pSdb, pVgroup);
     }
   }
 
diff --git a/source/libs/stream/src/streamTask.c b/source/libs/stream/src/streamTask.c
index c57015bc5f47313eafb603632c368b930a218a37..5152e43dbdbad6b60830167600d30eeaffe0d0a9 100644
--- a/source/libs/stream/src/streamTask.c
+++ b/source/libs/stream/src/streamTask.c
@@ -20,6 +20,7 @@
 SStreamTask* tNewStreamTask(int64_t streamId, int8_t taskLevel, int8_t fillHistory) {
   SStreamTask* pTask = (SStreamTask*)taosMemoryCalloc(1, sizeof(SStreamTask));
   if (pTask == NULL) {
+    terrno = TSDB_CODE_OUT_OF_MEMORY;
     return NULL;
   }