[SOLR-14451] debug=query does not reliably ensure json.facet debug info returned in cloud clusters

• Type: Bug
• Status: Open
• Priority: Major
• Resolution: Unresolved
• Component/s: Facet Module, SolrCloud
• Assignee: Unassigned
• Reporter: Chris M. Hostetter
• Created: 01/May/20 00:14
• Updated: 05/Dec/20 07:16

Description

While working on a randomized cloud test in SOLR-13132 that needs to inspect the "facet-trace" debug output to inspect the processor used (among other details), i discovered that FacetModule would not reliably initialize the FactDebugInfo container when using debug=query in the request.

AFAICT, it does appear to always track & return facet debugging info when using debug=true instead - but i haven't rigerously proved this.

Under the covers, FacetModule is just checking ResponseBuilder.isDebug() - an old "back compat" API for components to check before we started breaking down multiple types of "debug" info - that should return true anytime debug=query is set, so there is really no logical reason why this shouldn't work... it's got to be a bug somewhere (it doesn't seem tied to the request, but does break on diff randomized indexes, so perhaps it's related to the document/bucket distribution? or maybe something more low level and unrelated to FacetModule at all?)

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It only seems to be a problem in cloud mode - i haven't observed FacetModule's debug output behave any differently between debug=query vs debug=true in single node mode.