feat(stream): support nested event window sub-events by JinqingKuang · Pull Request #35149 · taosdata/TDengine

JinqingKuang · 2026-04-15T09:38:17Z

Description

Extend EVENT_WINDOW START WITH to accept nested condition trees.
Keep the outer true_for syntax backward compatible for existing stream definitions.
Allow leaf conditions to override true_for, while parent groups still inherit the outer setting.
Add _event_condition_path support through parser, node serialization, planning, and runtime.
Fix nested start-condition match reads in history and realtime execution so leaf true_for checks use the correct value width.
Refresh parser tests, stream system tests, and SQL documentation for nested starts, condition-path placeholders, and leaf-specific true_for behavior.

Issue(s)

Resolve: https://project.feishu.cn/taosdata_td/feature/detail/6952737120

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

Code Review

This pull request implements multi-level nested sub-event support for EVENT_WINDOW in stream processing. It introduces the _event_condition_path placeholder to identify matched nodes within a hierarchical start-condition tree and updates the notification payload to include conditionPath. The implementation includes changes to the parser, stream trigger task logic, and documentation. Feedback was provided regarding safer path length calculations and ensuring null-safety when evaluating event conditions.

Copilot

Pull request overview

This PR extends TDengine stream EVENT_WINDOW support to allow recursively nested START WITH groups, propagates a stable runtime “conditionPath” for matched nodes, and exposes that path via the new _event_condition_path placeholder and updated notification payload fields.

Changes:

Parser: add recursive START WITH grammar (start_event_item) and validation for _event_condition_path usage.
Runtime: build/start-condition metadata (node ids + stable paths), evaluate nested start trees, and propagate conditionPath through trigger calc params and notifications.
Function/Scalar plumbing: register _event_condition_path as a pseudo/placeholder function and populate its value at execution time; add tests and docs.

Reviewed changes

Copilot reviewed 19 out of 19 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
test/cases/18-StreamProcessing/03-TriggerMode/test_event_new.py	Adds a system test verifying nested start groups produce expected `_event_condition_path` values.
source/libs/scalar/src/scalar.c	Populates `_event_condition_path` placeholder results via new varstring setters.
source/libs/parser/test/parStreamTest.cpp	Adds parser tests for nested start condition AST shape and placeholder legality.
source/libs/parser/src/parTranslater.c	Tracks placeholder bitmap and enforces `_event_condition_path` validity for event windows with sub-events.
source/libs/parser/src/parTokenizer.c	Adds keyword mapping for `_EVENT_CONDITION_PATH`.
source/libs/parser/inc/sql.y	Introduces recursive `start_event_item` grammar and `_event_condition_path` pseudo column.
source/libs/new-stream/src/streamUtil.c	Updates event notification payload to include `conditionPath` + `conditionIndex` and removes `windowIndex`.
source/libs/new-stream/src/streamTriggerTask.c	Implements nested start-condition evaluation, path switching, and conditionPath propagation into calc params/notifications.
source/libs/new-stream/inc/streamTriggerTask.h	Extends window structs with `eventNodeId` and adds start-condition meta structures.
source/libs/new-stream/inc/streamInt.h	Updates `streamBuildEventNotifyContent` signature to accept `conditionPath`.
source/libs/function/src/functionMgt.c	Exposes `conditionPath` as a stream pseudo value and wires placeholder parameter updates.
source/libs/function/src/builtins.c	Registers `_event_condition_path` builtin and its return type handling.
source/common/src/msg/streamMsg.c	Serializes/deserializes `conditionPath` in `SSTriggerCalcParam` and frees it in destructor.
include/libs/function/functionMgt.h	Adds `FUNCTION_TYPE_EVENT_CONDITION_PATH`.
include/common/streamMsg.h	Adds placeholder bit + `conditionPath` field to trigger calc param struct.
docs/zh/06-advanced/03-stream.md	Documents nested `start_event_item` and `_event_condition_path` (ZH advanced).
docs/zh/14-reference/03-taos-sql/41-stream.md	Updates syntax/semantics and notification JSON fields (ZH reference).
docs/en/06-advanced/03-stream.md	Documents nested `start_event_item` and `_event_condition_path` (EN advanced).
docs/en/14-reference/03-taos-sql/41-stream.md	Updates syntax/semantics and notification JSON fields (EN reference).

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Pull request overview

Copilot reviewed 21 out of 21 changed files in this pull request and generated 3 comments.

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Copilot reviewed 27 out of 27 changed files in this pull request and generated 2 comments.

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Copilot · 2026-04-22T06:30:28Z

+  size_t len = strlen(pVal);
+  char*  buf = taosMemoryCalloc(len + VARSTR_HEADER_SIZE, 1);
+  if (buf == NULL) {
+    return terrno;
+  }
+  *(VarDataLenT*)buf = (VarDataLenT)len;
+  if (len > 0) {
+    (void)memcpy(varDataVal(buf), pVal, len);
+  }
+  int32_t code = colDataSetVal(pResColData, rowIndex, buf, false);
+  taosMemoryFreeClear(buf);
+  return code;
+}
+
+static int32_t sclSetVarDataCStringN(SColumnInfoData* pResColData, uint32_t currentRow, uint32_t numOfRows,
+                                     const char* pVal) {
+  if (pVal == NULL) {
+    colDataSetNItemsNull(pResColData, currentRow, numOfRows);
+    return TSDB_CODE_SUCCESS;
+  }
+
+  size_t len = strlen(pVal);
+  char*  buf = taosMemoryCalloc(len + VARSTR_HEADER_SIZE, 1);
+  if (buf == NULL) {
+    return terrno;
+  }
+  *(VarDataLenT*)buf = (VarDataLenT)len;
+  if (len > 0) {
+    (void)memcpy(varDataVal(buf), pVal, len);
+  }
+  int32_t code = colDataSetNItems(pResColData, currentRow, buf, numOfRows, 1, false);


sclSetVarDataCString/sclSetVarDataCStringN cast strlen(pVal) to VarDataLenT (uint16). If conditionPath (or any future caller) exceeds 65535 bytes, the length header will truncate and produce a malformed VARSTR. Add an explicit len <= UINT16_MAX check (and return an error or clamp consistently with other VARSTR builders) before writing the header.

Copilot · 2026-04-22T06:30:29Z

+      size_t len = strlen(pVal);
+      ((SValueNode*)pFirstParam)->datum.p = taosMemoryCalloc(len + VARSTR_HEADER_SIZE, 1);
+      if (NULL == ((SValueNode*)pFirstParam)->datum.p) {
+        return terrno;
+      }
+      (void)memcpy(varDataVal(((SValueNode*)pFirstParam)->datum.p), pVal, len);
+      varDataLen(((SValueNode*)pFirstParam)->datum.p) = len;
+      ((SValueNode*)pFirstParam)->isNull = false;


When populating the VARSTR for _event_condition_path, len is assigned from strlen(pVal) and then written into varDataLen(...) (VarDataLenT/uint16). If the path string is ever longer than 65535 bytes, this will overflow/truncate the VARSTR length header. Please validate the length (and fail or clamp) before allocating/writing the header.

- Extend EVENT_WINDOW START WITH to accept nested condition trees. - Keep the outer true_for syntax backward compatible for existing stream definitions. - Allow leaf conditions to override true_for, while parent groups still inherit the outer setting. - Add _event_condition_path support through parser, node serialization, planning, and runtime. - Fix nested start-condition match reads in history and realtime execution so leaf true_for checks use the correct value width. - Refresh parser tests, stream system tests, and SQL documentation for nested starts, condition-path placeholders, and leaf-specific true_for behavior. Co-authored-by: OpenAI Codex GPT-5 <noreply@openai.com>

Copilot AI review requested due to automatic review settings April 15, 2026 09:38

JinqingKuang requested review from a team, dapan1121, guanshengliang and zitsen as code owners April 15, 2026 09:38

taosdata-bot Bot added the internal label Apr 15, 2026

Copilot started reviewing on behalf of JinqingKuang April 15, 2026 09:39 View session

gemini-code-assist Bot reviewed Apr 15, 2026

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Comment thread source/libs/new-stream/src/streamTriggerTask.c Outdated

Comment thread source/libs/new-stream/src/streamTriggerTask.c

Copilot AI reviewed Apr 15, 2026

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Comment thread source/libs/new-stream/src/streamTriggerTask.c

JinqingKuang force-pushed the feat/event-window-multilevel-sub-events branch 2 times, most recently from cde25f3 to 4554448 Compare April 17, 2026 08:21

Copilot AI review requested due to automatic review settings April 17, 2026 08:21

Copilot started reviewing on behalf of JinqingKuang April 17, 2026 08:22 View session

Copilot AI reviewed Apr 17, 2026

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Comment thread conan/fast-lzma2/conanfile.py

Comment thread cmake/in/lzma2.Makefile

Comment thread source/libs/new-stream/inc/streamTriggerTask.h

JinqingKuang force-pushed the feat/event-window-multilevel-sub-events branch 2 times, most recently from 3ad9570 to 569b488 Compare April 21, 2026 08:08

Copilot AI review requested due to automatic review settings April 22, 2026 06:23

JinqingKuang force-pushed the feat/event-window-multilevel-sub-events branch from 569b488 to ef3d5b5 Compare April 22, 2026 06:23

Copilot started reviewing on behalf of JinqingKuang April 22, 2026 06:23 View session

Copilot AI reviewed Apr 22, 2026

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Jinqing Kuang and others added 2 commits April 23, 2026 15:15

fix(stream): format trigger code

3949ba1

JinqingKuang force-pushed the feat/event-window-multilevel-sub-events branch from ef3d5b5 to be5e94d Compare April 26, 2026 04:40

JinqingKuang closed this Apr 26, 2026

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feat(stream): support nested event window sub-events#35149

feat(stream): support nested event window sub-events#35149
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JinqingKuang commented Apr 15, 2026 •

edited

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JinqingKuang commented Apr 15, 2026 •

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