Horton

Re: Statistics Import and Export

Corey Huinker <corey.huinker@gmail.com>

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From: Corey Huinker <corey.huinker@gmail.com>
To: Peter Smith <smithpb2250@gmail.com>
Cc: Tomas Vondra <tomas.vondra@enterprisedb.com>, Ashutosh Bapat <ashutosh.bapat.oss@gmail.com>, pgsql-hackers@lists.postgresql.org
Date: 2024-02-02T08:37:10Z
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

(hit send before attaching patches, reposting message as well)

Attached is v4 of the statistics export/import patch.

This version has been refactored to match the design feedback received
previously.

The system views are gone. These were mostly there to serve as a baseline
for what an export query would look like. That role is temporarily
reassigned to pg_export_stats.c, but hopefully they will be integrated into
pg_dump in the next version. The regression test also contains the version
of each query suitable for the current server version.

The export format is far closer to the raw format of pg_statistic and
pg_statistic_ext_data, respectively. This format involves exporting oid
values for types, collations, operators, and attributes - values which are
specific to the server they were created on. To make sense of those values,
a subset of the columns of pg_type, pg_attribute, pg_collation, and
pg_operator are exported as well, which allows pg_import_rel_stats() and
pg_import_ext_stats() to reconstitute the data structure as it existed on
the old server, and adapt it to the modern structure and local schema
objects.

pg_import_rel_stats matches up local columns with the exported stats by
column name, not attnum. This allows for stats to be imported when columns
have been dropped, added, or reordered.

pg_import_ext_stats can also handle column reordering, though it currently
would get confused by changes in expressions that maintain the same result
data type. I'm not yet brave enough to handle importing nodetrees, nor do I
think it's wise to try. I think we'd be better off validating that the
destination extended stats object is identical in structure, and to fail
the import of that one object if it isn't perfect.

Export formats go back to v10.


On Mon, Jan 22, 2024 at 1:09 AM Peter Smith <smithpb2250@gmail.com> wrote:

> 2024-01 Commitfest.
>
> Hi, This patch has a CF status of "Needs Review" [1], but it seems
> there were CFbot test failures last time it was run [2]. Please have a
> look and post an updated version if necessary.
>
> ======
> [1] https://commitfest.postgresql.org/46/4538/
> [2]
> https://cirrus-ci.com/github/postgresql-cfbot/postgresql/commitfest/46/4538
>
> Kind Regards,
> Peter Smith.
>