Horton

Re: Extended Statistics set/restore/clear functions.

Michael Paquier <michael@paquier.xyz>

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From: Michael Paquier <michael@paquier.xyz>
To: jian he <jian.universality@gmail.com>
Cc: Corey Huinker <corey.huinker@gmail.com>, Tomas Vondra <tomas@vondra.me>, pgsql-hackers@lists.postgresql.org, tgl@sss.pgh.pa.us
Date: 2025-11-17T23:35:00Z
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 Mon, Nov 17, 2025 at 08:53:35PM +0800, jian he wrote:
> segfault:
> SELECT '[{"attributes" : [1,2,3,4,5,67,6,7,8], "ndistinct" : 4}]'::pg_ndistinct;
> 
> because src/backend/statistics/mvdistinct.c line: 310, Assert
> Assert((item->nattributes >= 2) && (item->nattributes <= STATS_MAX_DIMENSIONS));

Ahah, good one here.  Perhaps we had better switch this assertion to
become an elog() with the import functions in mind, as well.  It may
be worth double-checking the other deserialization paths, as well.  We
need to be super careful about this stuff for data imports.
--
Michael