Add PPL query cancellation via Discover cancel button by ahkcs · Pull Request #11593 · opensearch-project/OpenSearch-Dashboards

ahkcs · 2026-03-25T18:42:45Z

Summary

Generate a client-side UUID (queryId) for each synchronous PPL query and pass it through the full request pipeline to the OpenSearch /_plugins/_ppl endpoint
Add POST /api/enhancements/ppl/cancel server route that queries /_tasks?actions=*ppl*&detailed=true, matches tasks by queryId in the task description, and cancels all matching tasks via /_tasks/{taskId}/_cancel
Wire the existing Discover cancel button (abort flow) to call the new cancel route, enabling users to cancel long-running PPL queries from the UI
Each PPL search (data query and histogram aggregation) gets its own queryId, and both are cancelled independently when the user clicks cancel

Backend dependency

Depends on opensearch-project/sql#5254 (merged) which registers PPL queries as CancellableTask with the OpenSearch task framework.

Files changed

File	Change
`common/constants.ts`	Added `PPL_CANCEL` API path
`common/types.ts`	Added `queryId` to `EnhancedFetchContext`
`common/utils.ts`	Pass `queryId` in request body; call cancel route on abort
`public/search/ppl_search_interceptor.ts`	Generate UUID per PPL search
`server/routes/index.ts`	Accept `queryId` in route schema; register cancel route
`server/routes/ppl_cancel.ts`	New cancel route implementation
`server/routes/ppl_cancel.test.ts`	Unit tests (7 cases)
`server/utils/facet.ts`	Forward `queryId` to OpenSearch PPL API

Changelog

skip

E2E verification logs

Cancel both data + histogram queries (double join)

OSD server log — both tasks found and cancelled:

server log [18:29:34.131] [info][plugins][queryEnhancements] PPL query cancelled: queryId=ccfec0d5-9113-4489-8bd5-77ff64ae3c7f, taskId=cwL2x0XeS-i-g-kClRr0ew:2594
server log [18:29:34.134] [info][plugins][queryEnhancements] PPL query cancelled: queryId=0f863cc9-aab3-4589-9e88-191268f9f375, taskId=cwL2x0XeS-i-g-kClRr0ew:2593

OpenSearch backend log — both queries throw TaskCancelledException from cooperative isCancelled() check in moveNext():

[2026-03-25T11:29:34,131][ERROR][o.o.s.p.r.RestPPLQueryAction] Error happened during query handling
Caused by: org.opensearch.core.tasks.TaskCancelledException: The task is cancelled.
        at ...OpenSearchIndexEnumerator.moveNext(OpenSearchIndexEnumerator.java:122)

[2026-03-25T11:29:34,261][ERROR][o.o.s.p.r.RestPPLQueryAction] Error happened during query handling
Caused by: org.opensearch.core.tasks.TaskCancelledException: The task is cancelled.
        at ...OpenSearchIndexEnumerator.moveNext(OpenSearchIndexEnumerator.java:122)

OSD receives error responses confirming cancellation:

{
  "error": {
    "reason": "Error occurred in OpenSearch engine: The task is cancelled.",
    "type": "TaskCancelledException"
  },
  "status": 500
}

Test plan

Unit tests pass (7 tests for cancel route, all existing tests unaffected)
E2E tested: submit long-running PPL query, click cancel, verify both data and histogram tasks are cancelled via server logs
Both queries cancelled simultaneously — backend confirms TaskCancelledException from cooperative isCancelled() polling in moveNext()
Verified compatibility with backend PR sql#5254 (queryId field name, task description format, task action wildcard)

Enable cancellation of in-flight PPL queries from the Discover UI cancel button by leveraging the OpenSearch task framework. - Generate a client-side UUID (queryId) for each synchronous PPL query - Pass queryId through the full request pipeline to OpenSearch PPL API - Add POST /api/enhancements/ppl/cancel server route that lists PPL tasks via _tasks API, matches by queryId in task description, and cancels all matching tasks - Wire the existing Discover abort flow to call the cancel route on abort - Cancel all matching tasks (data + histogram queries share the same queryId) Depends on opensearch-project/sql#5254 for backend task registration. Signed-off-by: Kai Huang <ahkcs@amazon.com>

github-actions · 2026-03-25T18:43:14Z

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github-actions · 2026-03-25T18:43:27Z

❌ Invalid Changelog Heading

The '## Changelog' heading in your PR description is either missing or malformed. Please make sure that your PR description includes a '## Changelog' heading with proper spelling, capitalization, spacing, and Markdown syntax.

github-actions · 2026-03-25T18:43:33Z

PR Code Analyzer ❗

AI-powered 'Code-Diff-Analyzer' found issues on commit 0216993.

Path	Line	Severity	Description
src/plugins/query_enhancements/server/routes/ppl_cancel.ts	33	medium	The /_tasks endpoint is queried with no ownership check — any authenticated user can trigger this route and receive a list of ALL running PPL tasks across all nodes. Task descriptions may contain sensitive query content from other users, creating an information-disclosure risk. The feature's purpose (cancel your own query) does not require exposing other users' tasks.
src/plugins/query_enhancements/server/routes/ppl_cancel.ts	46	medium	No authorization check ties a queryId to the requesting user. Any authenticated user who knows (or guesses) another user's queryId can cancel that user's running PPL query. The queryId is a UUID generated client-side and sent over the wire, making it theoretically observable to a network-privileged attacker or via log inspection.
src/plugins/query_enhancements/server/routes/ppl_cancel.ts	44	low	The user-supplied queryId is interpolated directly into the targetPattern string used for substring matching against task descriptions (targetPattern = `queryId=${queryId}`). A value of empty string or a very short string (e.g. 'a') would match a large number of unrelated tasks and cancel them. The schema only enforces schema.string() with no minimum length or UUID format validation, so crafted inputs could cause unintended mass cancellation.

The table above displays the top 10 most important findings.

Total: 3 | Critical: 0 | High: 0 | Medium: 2 | Low: 1

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Thanks.

github-actions · 2026-03-25T18:44:20Z

Failed to generate code suggestions for PR

github-actions · 2026-03-25T18:45:28Z

❌ Invalid Changelog Heading

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github-actions · 2026-03-25T18:47:20Z

❌ Invalid Changelog Heading

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github-actions · 2026-03-25T18:48:32Z

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github-actions · 2026-03-25T18:50:07Z

Failed to generate code suggestions for PR

joshuali925 · 2026-03-25T21:09:17Z

+          } else if (context.body?.queryId) {
+            // Cancel synchronous PPL query via task cancellation
+            try {
+              await http.fetch({


is it better to not await this request? since frontend can't do much if cancel failed, it's job is to notify backend to cancel query, and it can move on. no need to block here in case PPL cancel API is stuck

Good call — updated to fire-and-forget. The cancel request now uses a .catch() chain instead of await, so the AbortError propagates immediately and the UI isn't blocked

joshuali925 · 2026-03-25T21:11:52Z

+          method: 'GET',
+          path: '/_tasks',
+          querystring: {
+            actions: '*ppl*',


can it be PPL * or something more specific, like searching for queryId?

The _tasks API doesn't support filtering by description or queryId — it only supports taskId, actions and parentTaskId. The queryId is embedded in the task description string (e.g. PPL [queryId=]: ...), so we have to list PPL tasks with detailed=true and match client-side. This is the only approach available without a backend change to expose a cancel-by-queryId endpoint.

Remove await from the cancel HTTP call so the AbortError propagates immediately. The cancel is a best-effort notification to the backend and should not block the frontend from moving on. Signed-off-by: Kai Huang <ahkcs@amazon.com>

github-actions · 2026-03-25T22:24:23Z

Failed to generate code suggestions for PR

Use 'cluster:admin/opensearch/ppl' instead of '*ppl*' to avoid matching unrelated tasks. The _tasks API does not support filtering by description or queryId, so client-side matching remains necessary. Signed-off-by: Kai Huang <ahkcs@amazon.com>

github-actions · 2026-03-25T22:37:11Z

Failed to generate code suggestions for PR

The exact action name is less resilient to future changes. The wildcard is sufficient since we still match by queryId in the task description. Signed-off-by: Kai Huang <ahkcs@amazon.com>

github-actions · 2026-03-25T22:54:01Z

Failed to generate code suggestions for PR

github-actions · 2026-03-25T23:55:10Z

✅ All unit and integration tests passing

🔗 Workflow run · commit 95a6f6dce32f9b24171943395981a205e33d4c1a

mengweieric · 2026-03-26T18:19:00Z

General question:

{
"error": {
"reason": "Error occurred in OpenSearch engine: The task is cancelled.",
"type": "TaskCancelledException"
},
"status": 500
}

Should the API return 4xx error code instead of 500? as this is not the backend error at all.

ahkcs · 2026-03-26T18:29:39Z

Should the API return 4xx error code instead of 500? as this is not the backend error at all.

Good call. I will open a follow-up PR on the backend side to change the classification of TaskCancelledException to 4xx

ahkcs · 2026-03-26T18:54:27Z

opensearch-project/sql#5273
Opened PR on the backend side to change the classification of TaskCancelledException
cc @mengweieric

Updated error message:

server    log   [19:02:02.468] [error][plugins][queryEnhancements] pplSearchStrategy: {
  "error": {
    "reason": "Query cancelled",
    "details": "The task is cancelled.",
    "type": "TaskCancelledException"
  },
  "status": 400

ahkcs · 2026-03-26T22:44:08Z

CI failure seems to be unrelated to our changes — this is an Explore app UI issue (autocomplete widget visibility)

Example:

https://github.com/opensearch-project/OpenSearch-Dashboards/actions/runs/23563713788/job/68611665458

codecov · 2026-03-26T23:04:32Z

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 0.00%. Comparing base (7782a80) to head (95a6f6d).
⚠️ Report is 22 commits behind head on main.

Additional details and impacted files

@@             Coverage Diff             @@
##             main   #11593       +/-   ##
===========================================
- Coverage   61.58%        0   -61.59%     
===========================================
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  Lines      137542        0   -137542     
  Branches    23901        0    -23901     
===========================================
- Hits        84707        0    -84707     
+ Misses      46692        0    -46692     
+ Partials     6143        0     -6143

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github-actions Bot added the failed changeset label Mar 25, 2026

Merge branch 'main' into feature/ppl-query-cancellation

a50537a

github-actions Bot added Skip-Changelog PRs that are too trivial to warrant a changelog or release notes entry and removed failed changeset labels Mar 25, 2026

joshuali925 reviewed Mar 25, 2026

View reviewed changes

Fire-and-forget PPL cancel request to avoid blocking UI

a47e90c

Remove await from the cancel HTTP call so the AbortError propagates immediately. The cancel is a best-effort notification to the backend and should not block the frontend from moving on. Signed-off-by: Kai Huang <ahkcs@amazon.com>

Revert action filter back to wildcard *ppl*

95a6f6d

The exact action name is less resilient to future changes. The wildcard is sufficient since we still match by queryId in the task description. Signed-off-by: Kai Huang <ahkcs@amazon.com>

ahkcs mentioned this pull request Mar 26, 2026

Classify TaskCancelledException as client error instead of system error opensearch-project/sql#5273

Draft

3 tasks

joshuali925 approved these changes Mar 26, 2026

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mengweieric approved these changes Mar 26, 2026

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mengweieric merged commit 494ecc7 into opensearch-project:main Mar 26, 2026
203 of 209 checks passed

ahkcs deleted the feature/ppl-query-cancellation branch March 26, 2026 23:23

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Summary

Backend dependency

Files changed

Changelog

E2E verification logs

Cancel both data + histogram queries (double join)

Test plan

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