Horton

Re: Statistics Import and Export

Corey Huinker <corey.huinker@gmail.com>

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From: Corey Huinker <corey.huinker@gmail.com>
To: Jeff Davis <pgsql@j-davis.com>
Cc: Stephen Frost <sfrost@snowman.net>, Matthias van de Meent <boekewurm+postgres@gmail.com>, Ashutosh Bapat <ashutosh.bapat.oss@gmail.com>, Peter Smith <smithpb2250@gmail.com>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>, Tomas Vondra <tomas.vondra@enterprisedb.com>
Date: 2024-03-18T03:33:57Z
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. Change pg_dump default for statistics export.

  2. pg_dump: Adjust reltuples from 0 to -1 for dumps of older versions.

  3. vacuumdb: Don't skip empty relations in --missing-stats-only mode.

  4. pg_dump: Fix query for gathering attribute stats on older versions.

  5. Prevent redeclaration of typedef TocEntry.

  6. Remove unused function parameters in pg_backup_archiver.c.

  7. pg_dump: Retrieve attribute statistics in batches.

  8. pg_dump: Reduce memory usage of dumps with statistics.

  9. Skip second WriteToc() call for custom-format dumps without data.

  10. Add relallfrozen to pg_dump statistics.

  11. Matview statistics depend on matview data.

  12. Add pg_dump --with-{schema|data|statistics} options.

  13. Stats: use schemaname/relname instead of regclass.

  14. CREATE INDEX: do update index stats if autovacuum=off.

  15. Don't convert to and from floats in pg_dump.

  16. CREATE INDEX: don't update table stats if autovacuum=off.

  17. Organize and deduplicate statistics import tests.

  18. Address stats export review comments.

  19. Address stats import review comments.

  20. Add relallfrozen to pg_class

  21. Fix pg_strtof() to not crash on NULL endptr.

  22. Use attnum to identify index columns in pg_restore_attribute_stats().

  23. pg_dump: prepare attribute stats query.

  24. Avoid unnecessary relation stats query in pg_dump.

  25. Remove redundant pg_set_*_stats() variants.

  26. Do not use in-place updates for statistics import.

  27. Fix confusion about data type of pg_class.relpages and relallvisible.

  28. Documentation fixups for dumping statistics.

  29. Trial fix for old cross-version upgrades.

  30. Transfer statistics during pg_upgrade.

  31. Lock table in ShareUpdateExclusive when importing index stats.

  32. Use in-place updates for pg_restore_relation_stats().

  33. Improve error message for replication of generated columns.

  34. pg_dump: Add dumpSchema and dumpData derivative flags.

  35. Disallow modifying statistics on system columns.

  36. Add missing CommandCounterIncrement() in stats import functions.

  37. Add functions pg_restore_relation_stats(), pg_restore_attribute_stats().

  38. Documentation fixup.

  39. Add functions pg_set_attribute_stats() and pg_clear_attribute_stats().

  40. Change pg_*_relation_stats() functions to return type to void.

  41. Disable autovacuum for tables in stats import tests.

  42. Allow pg_set_relation_stats() to set relpages to -1.

  43. Fixup for pg_set_relation_stats().

  44. Create functions pg_set_relation_stats, pg_clear_relation_stats.

  45. Add memory/disk usage for Window aggregate nodes in EXPLAIN.

  46. Improve performance of dumpSequenceData().

  47. Add INJECTION_POINT_CACHED() to run injection points directly from cache

  48. Improve performance of binary_upgrade_set_pg_class_oids().

  49. Improve assertion in mdwritev()

  50. CREATE INDEX: do not update stats during binary upgrade.

  51. Redefine pg_class.reltuples to be -1 before the first VACUUM or ANALYZE.

Attachments

>
>
> * pg_set_relation_stats() needs to do an ACL check so you can't set the
> stats on someone else's table. I suggest honoring the new MAINTAIN
> privilege as well.
>

Added.


>
> * If possible, reading from pg_stats (instead of pg_statistic) would be
> ideal because pg_stats already does the right checks at read time, so a
> non-superuser can export stats, too.
>

Done. That was sorta how it was originally, so returning to that wasn't too
hard.


>
> * If reading from pg_stats, should you change the signature of
> pg_set_relation_stats() to have argument names matching the columns of
> pg_stats (e.g. most_common_vals instead of stakind/stavalues)?
>

Done.


>
> In other words, make this a slightly higher level: conceptually
> exporting/importing pg_stats rather than pg_statistic. This may also
> make the SQL export queries simpler.
>

Eh, about the same.


> Also, I'm wondering about error handling. Is some kind of error thrown
> by pg_set_relation_stats() going to abort an entire restore? That might
> be easy to prevent with pg_restore, because it can just omit the stats,
> but harder if it's in a SQL file.
>

Aside from the oid being invalid, there's not a whole lot that can go wrong
in set_relation_stats(). The error checking I did closely mirrors that in
analyze.c.

Aside from the changes you suggested, as well as the error reporting change
you suggested for pg_dump, I also filtered out attempts to dump stats on
views.

A few TAP tests are still failing and I haven't been able to diagnose why,
though the failures in parallel dump seem to be that it tries to import
stats on indexes that haven't been created yet, which is odd because I sent
the dependency.

All those changes are available in the patches attached.