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Re: pg_plan_advice

Tom Lane <tgl@sss.pgh.pa.us>

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From: Tom Lane <tgl@sss.pgh.pa.us>
To: Robert Haas <robertmhaas@gmail.com>
Cc: PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2026-03-19T16:46:47Z
Lists: pgsql-hackers 
Robert Haas <robertmhaas@gmail.com> writes:
> I've now committed test_plan_advice, since it seems crazy to me to
> have pg_plan_advice in the tree without it and reviewers evidently
> agree at least with the concept test_plan_advice is something we
> should have. Here are the remaining two patches, as v21.

I just realized that this new test module has added yet another
execution of the entire core regression test suite ... and to add
insult to injury, it runs the planner twice for each plannable
query therein.  I think this is an outrageous abuse of our buildfarm
and urgently request that you find some less climate-destroying
way of getting reasonable test coverage of pg_plan_advice.

As an example of what this has done to our slower buildfarm members,
a few days ago my own animal longfin could run the BF script in 32
minutes and change, if not too much recompilation was needed.  Now its
minimum cycle time seems to be 35-plus minutes, or about 10% slower.
I don't think pg_plan_advice deserves that large a fraction of the
project's resources forevermore.

I don't see any good reason why you couldn't get adequate coverage of
pg_plan_advice with a few dozen queries.  Certainly all the DDL
testing that happens in the core regression tests isn't adding
anything here.

I would dig into why grison and schnauzer are failing this test,
except that I don't agree that we should be running it in the
first place.

			regards, tom lane

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.