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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: Lukas Fittl <lukas@fittl.com>, 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: 2026-02-07T16:25:57Z
Lists: pgsql-hackers 
Thanks for the review!

On Mon, Feb 2, 2026 at 2:37 PM Alexandra Wang
<alexandra.wang.oss@gmail.com> wrote:
> 0001:
> The code looks good to me. However, I feel a bit uneasy about not
> seeing a test case for the additional subplan origin display added in
> pg_overexplain. Maybe we could add the following test cases to
> exercise that code:

Done.

> 0002:
> Looks good to me.

Cool.

> 0003:
> in accumulate_append_subpath(), but in get_singleton_append_subpath()
> there are only calls to lappend() and no list_concat(). Is that
> intentional? Do we also want to concatenate the newly pulled up
> child_append_relid_sets with the existing ones in
> get_singleton_append_subpath()?

Oh, good catch! Adjusted.

> In add_paths_to_append_rel():
>
> @@ -1785,13 +1790,16 @@ add_paths_to_append_rel(PlannerInfo *root, RelOptInfo *rel,
>         {
>             Path       *path = (Path *) lfirst(l);
>             AppendPath *appendpath;
> +           AppendPathInput append = {0};
> +
> +           append.partial_subpaths = list_make1(path);
> +           append.child_append_relid_sets = list_make1(rel->relids);
>
> Could you help me understand why we need to populate
> append.child_append_relid_sets here? I don’t see this child rel being
> pulled up at this point.

Oops, good point. Adjusted this, too.

> 0004:
> I’ve only read through the README and documentation so far; I’ll
> continue reviewing the code in 0004.

Thanks!

I plan to post an updated patch set shortly.

-- 
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.