calc subq to runner #34457

stephenkgu · 2026-01-30T08:32:10Z

Description

Issue(s)

Close/close/Fix/fix/Resolve/resolve: Issue Link

Checklist

Please check the items in the checklist if applicable.

Is the user manual updated?
Are the test cases passed and automated?
Is there no significant decrease in test coverage?

gemini-code-assist · 2026-01-30T08:32:48Z

Summary of Changes

Hello @stephenkgu, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request significantly extends the system's capabilities by introducing comprehensive support for subqueries within stream calculation plans. It involves fundamental changes to how query plans are structured and processed, from their definition in header files to their execution by runners. The changes ensure that subqueries can be correctly parsed, translated, serialized, and integrated into the overall stream processing workflow, enabling more advanced and flexible stream analytics.

Highlights

Subquery Support in Stream Plans: The SSubplan structure now includes a pSubQ field, a SNodeList*, to store references to subqueries' subplans, enabling more complex stream calculations.
Enhanced Runner Task Building: The msmBuildRunnerTasksImpl function has been updated to distinguish between main query plans and subquery plans. It now creates SDownstreamSourceNodes for subquery results and manages their endpoints, ensuring proper data flow from subquery execution units.
Stream Reader Task Integration: A new function, msmUpdateCalcReaderTasks, was introduced to update stream reader tasks. It processes existing reader tasks, parses their calculation scan plans, and integrates the collected subquery endpoint information into them.
Executor Task Management for Subqueries: The qCreateStreamExecTask function in the executor has been modified to recognize and handle subquery endpoints. It now creates execution tasks that are aware of these subquery dependencies and can manage their lifecycle.
Serialization and Deserialization of Subquery Plans: JSON serialization and deserialization logic has been added for the new pSubQ field within SSubplan, allowing subquery plan structures to be persistently stored and transmitted across the system.
Parser Updates for CREATE STREAM: The parser now supports subqueries within CREATE STREAM statements. New functions, checkSubQueryStmt and transferSubQueries, were added and integrated into the stream calculation plan building process to correctly translate and manage subquery contexts.

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Code Review

This pull request introduces support for subqueries in stream calculations. The changes span across the parser, planner, and execution layers. A new field pSubQ is added to SSubplan to hold subquery information, and logic is added to build and manage runner tasks for these subqueries.

The overall approach is sound, but there are several areas for improvement:

There are critical risks of NULL pointer dereferences due to missing checks on plan structures.
The code contains some inefficiencies, such as repeated parsing of plan strings.
There are also minor issues like commented-out code and an incorrect type cast that should be addressed.

Please review the detailed comments for specific suggestions.

gemini-code-assist · 2026-01-30T08:34:34Z

source/dnode/mnode/impl/src/mndStreamMgmt.c

+  SNodeList*     pSubEP = NULL;

  TAOS_CHECK_EXIT(nodesStringToNode(pStream->pCreate->calcPlan, (SNode**)&pPlan));
+  pSubQPlan = (SQueryPlan*)pPlan->pChildren->pHead->pNode;


This line accesses pPlan->pChildren->pHead->pNode without checking if pPlan->pChildren or pPlan->pChildren->pHead are NULL. This could lead to a NULL pointer dereference and a crash. Please add checks to handle this case gracefully.

if (pPlan->pChildren == NULL || pPlan->pChildren->pHead == NULL || pPlan->pChildren->pHead->pNode == NULL) { mstsError("stream:%s invalid calc plan, no subquery plan found", pStream->pCreate->name); code = TSDB_CODE_INVALID_SQL; goto _exit; } pSubQPlan = (SQueryPlan*)pPlan->pChildren->pHead->pNode;

gemini-code-assist · 2026-01-30T08:34:34Z

source/libs/parser/src/parTranslater.c

  }

+  // TODO: for each subquery plan do the following plan xform
+  SQueryPlan* calcSubQPlan = ((SQueryPlan*)calcPlan ->pChildren ->pHead ->pNode);


This line accesses calcPlan->pChildren->pHead->pNode without any checks for NULL pointers. This is unsafe and can lead to a crash if pChildren or pHead is NULL. Please add validation to ensure these pointers are valid before dereferencing them.

if (calcPlan->pChildren == NULL || calcPlan->pChildren->pHead == NULL || calcPlan->pChildren->pHead->pNode == NULL) { PAR_ERR_JRET(TSDB_CODE_INVALID_SQL); } SQueryPlan* calcSubQPlan = ((SQueryPlan*)calcPlan ->pChildren ->pHead ->pNode);

gemini-code-assist · 2026-01-30T08:34:34Z

source/dnode/mnode/impl/src/mndStreamMgmt.c

+  code = msmBuildRunnerTasksImpl(pCtx, pSubQPlan, pInfo, pStream, pPlan, &pSubEP);
+  pPlan = NULL;
+  TAOS_CHECK_EXIT(code);
+  TAOS_CHECK_EXIT(nodesStringToNode(pStream->pCreate->calcPlan, (SNode**)&pPlan));
+  code = msmBuildRunnerTasksImpl(pCtx, pPlan, pInfo, pStream, pPlan, &pSubEP);
  pPlan = NULL;


The calculation plan is parsed from a string (nodesStringToNode) multiple times within this function and also within the called function msmBuildRunnerTasksImpl. This is inefficient. Consider parsing it once at the beginning, and if the plan needs to be modified by a function, pass a clone of the plan instead of destroying and re-parsing it. This would improve performance and make the data flow clearer.

gemini-code-assist · 2026-01-30T08:34:34Z

source/libs/executor/src/executor.c

+  SDownstreamSourceNode* pSource = NULL;
+
+  for (int32_t i = 0; i < subTaskNum; ++i) {
+    SValueNode* pVal = (SValueNode*)nodesListGetNode(pSubplan->pSubQ, i);


The node from pSubplan->pSubQ is cast to SValueNode*, but based on how it's created in mndStreamMgmt.c, it should be a SDownstreamSourceNode*. This cast is misleading and potentially incorrect. Please use the correct type, SDownstreamSourceNode*, or a generic SNode* to avoid confusion and potential bugs.

SNode* pVal = (SNode*)nodesListGetNode(pSubplan->pSubQ, i);

gemini-code-assist · 2026-01-30T08:34:34Z

source/dnode/mnode/impl/src/mndStreamMgmt.c

+    // SQueryPlan* calcSubQPlan = ((SQueryPlan*)pDag->pChildren->pHead->pNode);
+    // SNodeList*  subQSubplans = calcSubQPlan->pSubplans;


These lines are commented out. If this code is no longer needed, it should be removed to improve code clarity.

gemini-code-assist · 2026-01-30T08:34:34Z

source/dnode/mnode/impl/src/mndStreamMgmt.c

+	if (subQ) {
+          SStmTaskSrcAddr addr = {0};
+          SDownstreamSourceNode* pSource = NULL;
+
+          TAOS_CHECK_EXIT(nodesMakeNode(QUERY_NODE_DOWNSTREAM_SOURCE, (SNode**)&pSource));
+
+          addr.taskId = pDeploy->task.taskId;
+          addr.vgId = pDeploy->task.nodeId;
+          addr.groupId = plan->id.groupId;
+          addr.epset = mndGetDnodeEpsetById(pCtx->pMnode, pDeploy->task.nodeId);
+
+          pSource->addr.epSet = addr.epset;
+          pSource->addr.nodeId = addr.vgId;
+
+          pSource->clientId = streamId;
+          pSource->taskId = pDeploy->task.taskId;
+          pSource->sId = 0;
+          pSource->execId = 0;
+          pSource->fetchMsgType = TDMT_STREAM_FETCH_FROM_RUNNER;
+          pSource->localExec = false;
+
+          code = nodesListMakeStrictAppend(subEP, (SNode *)pSource);
+          if (code) {
+            TAOS_CHECK_EXIT(code);
+          }
+	} else {
+	  TAOS_CHECK_EXIT(nodesCloneList(*subEP, &plan->pSubQ));
+	}


The indentation in this if/else block seems to be inconsistent with the surrounding code, possibly due to mixed tabs and spaces. Please fix the indentation to improve readability.

gemini-code-assist · 2026-01-30T08:34:34Z

source/dnode/mnode/impl/src/mndStreamMgmt.c

+static int32_t msmUpdateCalcReaderTasks(SStreamObj* pStream, SNodeList* pSubEP) {
+  int32_t code = TSDB_CODE_SUCCESS;
+  int32_t lino = 0;
+  int64_t streamId = pStream->pCreate->streamId;


The variable streamId is initialized but never used in this function. It should be removed if it's not needed.

gemini-code-assist · 2026-01-30T08:34:34Z

source/dnode/mnode/impl/src/mndStreamMgmt.c

+      // string to node
+      // for each subplan, adjoin subEP
+      // node to the string of calcScanPlan


These commented-out lines appear to be notes or old code. They should be removed to keep the codebase clean.

calc subq to runner

c3293c5

stephenkgu requested review from dapan1121, guanshengliang and hzcheng as code owners January 30, 2026 08:32

taosdata-bot bot added the team engine label Jan 30, 2026

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calc subq to runner #34457

calc subq to runner #34457

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		// SQueryPlan* calcSubQPlan = ((SQueryPlan*)pDag->pChildren->pHead->pNode);
		// SNodeList* subQSubplans = calcSubQPlan->pSubplans;

calc subq to runner #34457

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stephenkgu commented Jan 30, 2026

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