Horton

Re: Statistics Import and Export

Corey Huinker <corey.huinker@gmail.com>

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From: Corey Huinker <corey.huinker@gmail.com>
To: Greg Sabino Mullane <htamfids@gmail.com>
Cc: Tom Lane <tgl@sss.pgh.pa.us>, Jeff Davis <pgsql@j-davis.com>, Ashutosh Bapat <ashutosh.bapat.oss@gmail.com>, Andres Freund <andres@anarazel.de>, Michael Paquier <michael@paquier.xyz>, Nathan Bossart <nathandbossart@gmail.com>, Bruce Momjian <bruce@momjian.us>, Matthias van de Meent <boekewurm+postgres@gmail.com>, Magnus Hagander <magnus@hagander.net>, Stephen Frost <sfrost@snowman.net>, Peter Smith <smithpb2250@gmail.com>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>, alvherre@alvh.no-ip.org, jian he <jian.universality@gmail.com>
Date: 2025-03-05T08:08:55Z
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

Attached are a couple updates that fell by the wayside and I'd like to
bring focus back to them, plus one potential change, and a recap of where
things stand.

0001 is a patch from Jian He [1] which removes a logic deduplication and I
believe should be committed.
0002 is some attempt to cull the regression tests, eliminating extraneous
parameters where possible, and reorganizing the tests

0003 is a bit more experimental.

In the interest of reducing potential ERRORs raised by
pg_restore_relation_stats and pg_restore_attribute_stats within a restore
or upgrade, the possibility that we attempt to restore stats to a relation
that does not yet exist means that the 'foo.bar'::regclass call will fail
with an ERROR. If, however, we replace the relation regclass parameter with
text parameters schemaname and relname, we have the flexibility to catch
this particular scenario and turn it into a WARNING instead. Likewise, if
we change the attname parameter to text, we avoid those casts as well.

I'm seeking feedback on whether people think this is a positive change.

TODO

1. If the schemaname/relname change is amenable, there are some other
conditions where we currently raise errors but could instead issue a
WARNING instead and return false. We should settle on our preference
soon-ish.

2. Commit 99f8f3fbbc8f74 introduced relallfrozen to pg_class, and pg_dump
does not presently dump relallfrozen stats. I can implement this pending
the feedback on schemaname/relname vs relation regclass.

3. We still have a gap in functionality in that we do not currently dump
and restore extended stats. That patchset was recently updated and is
covered in thread [3]. I know time is getting short, but having this at the
same time would
reduce the number of customers who need to use the new vacuumdb option
under development in [4], and reduce customer confusion concerning whether
they are in need of post-upgrade analyzing of anything.


[1]
https://www.postgresql.org/message-id/flat/CACJufxFVq%3Dtq9u1zrHWYSbMi1T07gS9Ff0LJScMco4HZmtZ1xw%40mail.gmail.com
[2]
https://www.postgresql.org/message-id/flat/CAExHW5sNgxkqkyscm9KRrcwvi%2B_Hg%3DPRe_u%2BxZYJzX%2Bw4XAMjQ%40mail.gmail.com#93c77f59150be1471c38f1a315772215
[3]
https://www.postgresql.org/message-id/flat/CADkLM%3DdnFKZMAo7MwqD2X6JjiiLCoVXHmszqtZp8sycYmoCcMQ%40mail.gmail.com#eff41d39f7158086e8398803165c5c2f
[4]
https://www.postgresql.org/message-id/flat/CANWCAZZf_jNn2i%2B6-JfQt_j909DBk-U6Dg0M7iArZPLgdXCAmw%40mail.gmail.com#e575b5bede51455f406ac3872d2f82ec