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Re: pg_plan_advice

Robert Haas <robertmhaas@gmail.com>

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From: Robert Haas <robertmhaas@gmail.com>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Matheus Alcantara <matheusssilv97@gmail.com>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2026-03-19T22:19:17Z
Lists: pgsql-hackers 
On Thu, Mar 19, 2026 at 6:03 PM Tom Lane <tgl@sss.pgh.pa.us> wrote:
> Please note that I was citing the runtime of a much slower machine
> (longfin is a 2018 mac mini).  But in any case, what I was griping
> about was the additional cost added to a buildfarm run; I don't see
> that test_plan_advice is a lot slower than the main regression tests.
> It's just that those are already a significant investment, and we
> just iterated them another time.

Right, and there's definitely plenty of worthless crap in there that
isn't adding any value. For example, every \dWHATEVER command in the
regression test is running basically the same queries every time, and
after the first time we're probably not learning anything new. And all
the DDL commands that are part of the regression tests are fairly
useless here. The grison failure is actually triggered by a DDL
command, but I think that might just be luck rather than the
test_plan_advice module is doing anything to systematically increase
the likelihood of such findings. But I don't know how we can separate
the wheat from the chaff. Obviously a lot of the DDL and \d commands
in the tests are either setup for queries that we should care about
testing, or verification that those queries did what they were
supposed to do. If we split the main regression test suite up, so that
we had one test suite for planner-related stuff, another for DDL, and
another for data types, or something like that, then test_plan_advice
would probably mostly just need to run on the first of those. But that
kind of split seems like a lot of work.

Do you think the idea of piggybacking the test_plan_advice run onto
another run that we're already doing has any potential? That would
reduce the incremental cost quite a lot, I think.

-- 
Robert Haas
EDB: http://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.