WDQS UI fails on large queries
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	Smalyshev
	Jan 16 2019, 7:39 AM

Description

If you put a large query into WDQS GUI, it would produce 414 Request-URI Too Large since URI size is limited. However, WDQS supports also POST queries now, so instead the GUI should switch to POST from GET when certain threshold (probably should be configurable) has been passed.

Details

	Subject	Repo	Branch	Lines +/-
	Merging from e9f3dd43523caa0878ca01f21b1e431c0b4b70be:	wikidata/query/gui-deploy	production	+4 -4
	Retry queries with POST if server indicates request was too large	wikidata/query/gui	master	+5 -1

Customize query in gerrit

Related Objects

Mentioned In: rWDQGe9f3dd43523c: Retry queries with POST if server indicates request was too large
T216590: Queries of a certain size-range produce errors in Wikidata Query Service GUI
Mentioned Here: rWDQGe9f3dd43523c: Retry queries with POST if server indicates request was too large

Event Timeline

Smalyshev created this task.Jan 16 2019, 7:39 AM

Restricted Application added a project: Wikidata. · View Herald TranscriptJan 16 2019, 7:39 AM

Restricted Application added a subscriber: Aklapper. · View Herald Transcript

This was implemented long ago (apparently without a Phabricator task, but see Ic770e25bb4 and Ic3ea53c50e), but I guess something is behaving differently now? I don’t recall seeing an HTTP 414 error back then, the request just wouldn’t be sent at all (client-side limit).

Well, maybe there's some gap between client-side and server-side limits?

I see the code is:

if ( request.getAllResponseHeaders() === '' ) {
  // query might have been too long for GET, retry with POST
  settings.method = 'POST';
  $.ajax( self._serviceUri, settings ).done( done ).fail( fail );
}

I suspect when the server rejects it, the headers are not empty. It also can be a proxy on the way rejecting it, of course.

Yeah, the existing code only detects when the browser doesn’t send a request at all, so I guess there must now be some length that the browser still sends but the server rejects.

This would of course be easier to debug if the reporting user on Wikidata provided the failing query :/

NoInkling mentioned this in T216590: Queries of a certain size-range produce errors in Wikidata Query Service GUI.Feb 20 2019, 6:06 AM

NoInkling subscribed.Feb 20 2019, 6:23 AM

Change 494282 had a related patch set uploaded (by Lucas Werkmeister (WMDE); owner: Lucas Werkmeister (WMDE)):
[wikidata/query/gui@master] Retry queries with POST if server indicates request was too large

https://gerrit.wikimedia.org/r/494282

gerritbot added a project: Patch-For-Review.Mar 4 2019, 6:29 PM

Lucas_Werkmeister_WMDE mentioned this in rWDQGe9f3dd43523c: Retry queries with POST if server indicates request was too large.Mar 4 2019, 6:36 PM

Change 494282 merged by jenkins-bot:
[wikidata/query/gui@master] Retry queries with POST if server indicates request was too large

https://gerrit.wikimedia.org/r/494282

Change 494376 had a related patch set uploaded (by WDQSGuiBuilder; owner: WDQSGuiBuilder):
[wikidata/query/gui-deploy@production] Merging from e9f3dd43523caa0878ca01f21b1e431c0b4b70be:

https://gerrit.wikimedia.org/r/494376

Change 494376 abandoned by Smalyshev:
Merging from e9f3dd43523caa0878ca01f21b1e431c0b4b70be:

Reason:
superceded