Horton
Menu

Re: pg_plan_advice

Matheus Alcantara <matheusssilv97@gmail.com>

View thread
From: Matheus Alcantara <matheusssilv97@gmail.com>
To: Robert Haas <robertmhaas@gmail.com>, Lukas Fittl <lukas@fittl.com>
Cc: Tom Lane <tgl@sss.pgh.pa.us>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2026-03-26T14:30:40Z
Lists: pgsql-hackers 
On 26/03/26 10:55, Robert Haas wrote:
>> I realize not having query texts reduces its effectiveness (since you
>> don't see which parameters produced which plan advice), but it still
>> helps surface which different advice strings where seen for which
>> query IDs, letting you identify if you're getting a mix of bad and
>> good plans. And I'm just really worried people will enable this on
>> production in shared collection mode and take down their system.
> 
> I fully admit that pg_collect_advice is crude, but I don't think
> ripping out some portion of the limited functionality that it has is
> going to get us where we want to be. If it hadn't collected the query
> strings, it would have been useless for the purpose for which I
> originally wrote it. We could add a GUC for a length limit, perhaps,
> but I think the real feature that this needs to be used in the way
> that you seem to want to use it is deduplication, and as I said
> earlier, I think we should consider adding the advice collection logic
> to pg_stat_statements rather than building an alternative version of
> that module with overlapping functionality.
>

I also think that we should consider adding the advice string on 
pg_stat_statements. It seems to make more sense to me IMHO.

Adding support for auto_explain to explain(plan_advice, ...) (or any 
other custom explain option from loadable modules) would help or make 
sense here? I have been thinking about this for a while.


--
Matheus Alcantara
EDB: https://www.enterprisedb.com

Commits

Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →

  1. pg_plan_advice: Fix another unique-semijoin bug.

  2. pg_plan_advice: Export feedback-related definitions.

  3. pg_plan_advice: Fix a bug when a subquery is pruned away entirely.

  4. pg_plan_advice: Add alternatives test to Makefile.

  5. pg_plan_advice: Handle non-repeatable TABLESAMPLE scans.

  6. pg_stash_advice: Allow stashed advice to be persisted to disk.

  7. Add pg_stash_advice contrib module.

  8. pg_plan_advice: Avoid assertion failure with partitionwise aggregate.

  9. pg_plan_advice: Invent DO_NOT_SCAN(relation_identifier).

  10. Add an alternative_plan_name field to PlannerInfo.

  11. pg_plan_advice: Refactor to invent pgpa_planner_info

  12. Respect disabled_nodes in fix_alternative_subplan.

  13. get_memoize_path: Don't exit quickly when PGS_NESTLOOP_PLAIN is unset.

  14. test_plan_advice: Set TAP test priority 50 in meson.build.

  15. pg_plan_advice: Avoid a crash under GEQO.

  16. Test pg_plan_advice using a new test_plan_advice module.

  17. pg_plan_advice: Always install pg_plan_advice.h, and in the right place

  18. pg_plan_advice: Fix failures to accept identifier keywords.

  19. Add pg_plan_advice contrib module.

  20. Allow extensions to mark an individual index as disabled.

  21. Replace get_relation_info_hook with build_simple_rel_hook.

  22. Store information about Append node consolidation in the final plan.

  23. Store information about elided nodes in the final plan.

  24. Store information about range-table flattening in the final plan.

  25. Pass cursorOptions to planner_setup_hook.

  26. Fix PGS_CONSIDER_NONPARTIAL interaction with Materialize nodes.

  27. Fix mistakes in commit 4020b370f214315b8c10430301898ac21658143f

  28. Allow for plugin control over path generation strategies.

  29. Update some comments for fasthash

  30. Allow passing a pointer to GetNamedDSMSegment()'s init callback.

  31. Don't reset the pathlist of partitioned joinrels.

  32. Treat number of disabled nodes in a path as a separate cost metric.