Horton

Re: Extended Statistics set/restore/clear functions.

Michael Paquier <michael@paquier.xyz>

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From: Michael Paquier <michael@paquier.xyz>
To: Corey Huinker <corey.huinker@gmail.com>
Cc: Tomas Vondra <tomas@vondra.me>, jian he <jian.universality@gmail.com>, pgsql-hackers@lists.postgresql.org, tgl@sss.pgh.pa.us
Date: 2025-11-06T08:26:58Z
Lists: pgsql-hackers

Commits

Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →

  1. Add test doing some cloning of extended statistics data

  2. Add test for pg_restore_extended_stats() with multiranges

  3. Add support for "mcv" in pg_restore_extended_stats()

  4. Include extended statistics data in pg_dump

  5. Add support for "dependencies" in pg_restore_extended_stats()

  6. Add test for MAINTAIN permission with pg_restore_extended_stats()

  7. Add pg_restore_extended_stats()

  8. Add routine to free MCVList

  9. Improve pg_clear_extended_stats() with incorrect relation/stats combination

  10. Add pg_clear_extended_stats()

  11. Introduce routines to validate and free MVNDistinct and MVDependencies

  12. Fix typo in stat_utils.c

  13. Move attribute statistics functions to stat_utils.c

  14. Improve error messages of input functions for pg_dependencies and pg_ndistinct

  15. Improve test output of extended statistics for ndistinct and dependencies

  16. Fix some compiler warnings

  17. Add input function for data type pg_dependencies

  18. Add input function for data type pg_ndistinct

  19. Rework output format of pg_dependencies

  20. Rework output format of pg_ndistinct

  21. Fix comments of output routines for pg_ndistinct and pg_dependencies

  22. Move code specific to pg_dependencies to new file

  23. Move code specific to pg_ndistinct to new file

  24. Document some structures in attribute_stats.c

  25. Fix FATAL message for invalid recovery timeline at beginning of recovery

On Wed, Nov 05, 2025 at 01:38:56AM -0500, Corey Huinker wrote:
> Paquier's response got sidetracked because of an errant subject line
> change, so I will try to recap:

That was a typo that found its way into the email subject.  Sorry
about that, that broke gmail's tracking at least.

> in that off-list discussion I proposed (though I was mostly echoing what I
> thought Paquier wanted):
> 
> 1. pg_ndistinct output function change.
> 2. pg_ndistinct input function addition.
> 3. pg_dependencies output function change
> 4. pg_dependencies input function
> 5. Expose attribute statistics function and rename them attstat_* or
> statatt_*   (edit: and fix lack of comments on the enums and arrays)
> 6. pg_restore_extended_stats
> 7. pg_dump with no ability to fetch old-format pg_ndistinct/pg_dependences.
> (edit: and fix inherited bug)
> 8. pg_dump working back as far as possible

Thanks.  I have begun reviewing it (more a bit later, still need to
study more the structure of the code).  For now, I have extracted some
of the comment changes in 0005 and applied these independently.

> Given that the pg_dump code no longer seems as bad, and Tomas is very much
> in support of it, I've opted not to split out steps 7/8.

That sounds like a way forward to me, then, in terms of using a new
format and make pg_dump intelligent enough to deal with it based on
what's in the past versions.
--
Michael