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Re: pg_plan_advice

Robert Haas <robertmhaas@gmail.com>

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From: Robert Haas <robertmhaas@gmail.com>
To: Alexandra Wang <alexandra.wang.oss@gmail.com>
Cc: "David G. Johnston" <david.g.johnston@gmail.com>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2026-03-16T17:34:59Z
Lists: pgsql-hackers 
On Thu, Mar 12, 2026 at 7:46 PM Alexandra Wang
<alexandra.wang.oss@gmail.com> wrote:
> For the make tests, I had to add
>
> +EXTRA_INSTALL = contrib/pg_plan_advice

Thanks, will fix.

> There is a typo in the commit message:
> "pg_stash.advice_stash" should be "pg_stash_advice.stash_name".

Thanks, will fix.

> I doubt there will be more than 2 billion stashes in the system, but
> if in any case we reach that number, we don't handle int overflow.
> Should we set a limit on how many stashes can be stored?

I think the thing to do here is just change the stash ID to a 64-bit
value. I'll do that in the next version. We assume in numerous places
that a 64-bit integer never overflows (e.g. LSNs) which is pretty fair
considering how long it would take for that to happen.

> Nit:
> find_defelem_by_defname() is defined in all three modules, and also in
> pg_plan_advice. Knowing it is very small, would it make sense to
> extern the one in pg_plan_advice and reuse it?

I think if we want to avoid duplicating this function, we should
actually put it someplace in core, e.g. expose it via defrem.h and put
the code in commands/define.c. Any user of extendplan.h is likely to
need a function like this, but we shouldn't put it there because there
could be other use cases as well.

-- 
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.