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Re: pg_plan_advice

David G. Johnston <david.g.johnston@gmail.com>

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From: "David G. Johnston" <david.g.johnston@gmail.com>
To: Robert Haas <robertmhaas@gmail.com>
Cc: Alexandra Wang <alexandra.wang.oss@gmail.com>, Richard Guo <guofenglinux@gmail.com>, Lukas Fittl <lukas@fittl.com>, Tom Lane <tgl@sss.pgh.pa.us>, 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: 2026-03-04T15:44:42Z
Lists: pgsql-hackers 
On Wed, Mar 4, 2026 at 8:17 AM Robert Haas <robertmhaas@gmail.com> wrote:

> On Fri, Feb 27, 2026 at 8:16 PM David G. Johnston
> <david.g.johnston@gmail.com> wrote:
> > I have a mind to walk through the readmes and sgmls but its going to be
> in chunks.  Here's one for the readme for pg_plan_advice with a couple of
> preliminary sgml changes.
>
> While I'm grateful for the feedback, I feel like you tend to suggest a
> lot of edits that seem like they're just substituting your
> idiosyncratic preferences for mine


Yeah, some of these end up being mostly stylistic.  Though I do try to
limit them to ones where I see inconsistency or the style I'm reading just
doesn't resonate with me.  I usually point out the ones that are IMO
material, versus just something that tripped me up while I was reading, but
failed to do so here.

I do need to work in a way to better annotate/comment on the why of these.
Any suggestions for a better flow or feedback format?  Inline comments
wrapped in sgml comments?  Or just copy the diff into the email body and
inline comment there - leaving the original diff attachment as-is?


> -  advice" mini-language. It is intended to allow stabilization of plan
> choices
> +  advice" domain specific language (DSL). It is intended to allow
> stabilization of plan choices
>
> There's a debate to be had about whether it's better to say
> mini-language or domain specific language here, but it's hard for me
> to decide which is better if all you provide is a diff replacing A
> with B. I definitely think it's worse to write (DSL) here. There is no
> point in defining an acronym if we're never going to use it anywhere.
>
>
This was truly just a "have you considered using this terminology instead"
kind of prompt.  The acronym would have been useful when going an replacing
the other uses of mini-language that I left alone since I hadn't myself
decided which one was better.

I didn't do my usual email recap on this first patch which is my bad.  I
corrected that with the others.

David J.

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.