Horton

Re: Extended Statistics set/restore/clear functions.

Corey Huinker <corey.huinker@gmail.com>

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From: Corey Huinker <corey.huinker@gmail.com>
To: jian he <jian.universality@gmail.com>
Cc: Tomas Vondra <tomas@vondra.me>, pgsql-hackers@lists.postgresql.org
Date: 2025-01-29T19:56:33Z
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 Tue, Jan 28, 2025 at 11:25 AM jian he <jian.universality@gmail.com>
wrote:

> hi.
> I reviewed 0001 only.
>
> in src/backend/statistics/mvdistinct.c
>
> no need #include "nodes/pg_list.h" since
> src/include/statistics/statistics.h sub level include "nodes/pg_list.h"
>
> no need #include "utils/palloc.h"
> sicne #include "postgres.h"
> already included it.
>


Noted.


>  select '[{"6, -32768,,": -11}]'::pg_ndistinct;
> ERROR:  malformed pg_ndistinct: "[{"6, -32768,,": -11}]"
> LINE 1: select '[{"6, -32768,,": -11}]'::pg_ndistinct;
>                ^
> DETAIL:  All ndistinct count values are scalar doubles.
> imho, this errdetail message is not good.
>

What error message do you think is appropriate in that situation?


> select '{}'::pg_ndistinct ;
> segfault
>

Mmm, gotta look into that!



>
>
> select '{"1,":"1"}'::pg_ndistinct ;
> ERROR:  malformed pg_ndistinct: "{"1,":"1"}"
> LINE 1: select '{"1,":"1"}'::pg_ndistinct ;
>                ^
> DETAIL:  All ndistinct attnum lists must be a comma separated list of
> attnums.
>
> imho, this errdetail message is not good. would be better saying that
> "length of list of attnums must be larger than 1".
>

That sounds better.



> typcategory (Z) marked as Internal-use types. and there is no
> pg_ndistinct array type,
> not sure this is fine.
>

I think it's probably ok for now. The datatype currently has no utility
other than extended statistics, and I'm doubtful that it ever will.