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Re: pg_plan_advice

Lukas Fittl <lukas@fittl.com>

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From: Lukas Fittl <lukas@fittl.com>
To: Robert Haas <robertmhaas@gmail.com>
Cc: Jacob Champion <jacob.champion@enterprisedb.com>, Dian Fay <di@nmfay.com>, Matheus Alcantara <matheusssilv97@gmail.com>, Jakub Wartak <jakub.wartak@enterprisedb.com>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2026-01-08T19:13:43Z
Lists: pgsql-hackers 
On Thu, Jan 8, 2026 at 10:22 AM Robert Haas <robertmhaas@gmail.com> wrote:
> 0004: Comment update, bug fix to cost_index() per comment from Lukas.

Thanks! I've tested this and this works as expected on current master
with the updated pg_hint_plan code, and checking for tablesample in
the code that sets the mask.

On Thu, Jan 8, 2026 at 8:38 AM Robert Haas <robertmhaas@gmail.com> wrote:
> On Thu, Jan 8, 2026 at 11:31 AM Lukas Fittl <lukas@fittl.com> wrote:
> > Yeah, I would agree with you that is inconsistent with the flag's name
> > - but on the flip side, its difficult for the caller to conditionally
> > set the flag (which you'd have to do to avoid a "Disabled" showing in
> > the plan), since we're setting it on the RelOptInfo (do we know if the
> > scan is a sample scan at that point?).
>
> How about checking rte->tablesample, as set_rel_pathlist does?

Yeah, that works - its a bit inconvenient for two reasons, but I don't
think that warrants a redesign:

1) get_relation_info_hook doesn't get a RangeTblEntry passed (like
set_rel_pathlist_hook), but that's solvable by looking it up via
simple_rte_array
2) It requires maintaining a special case in the logic that says "make
it parallel", vs the planner that is authoritative (i.e. if we add
more special cases in the future, each extension will have to be
updated to reflect that)

Thanks,
Lukas

-- 
Lukas Fittl

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.