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: Robert Treat <rob@xzilla.net>, Robert Haas <robertmhaas@gmail.com>, Andres Freund <andres@anarazel.de>, Nathan Bossart <nathandbossart@gmail.com>, Tom Lane <tgl@sss.pgh.pa.us>, Michael Paquier <michael@paquier.xyz>, jian he <jian.universality@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>, Ashutosh Bapat <ashutosh.bapat.oss@gmail.com>, Peter Smith <smithpb2250@gmail.com>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>, alvherre@alvh.no-ip.org
Date: 2025-03-14T20:03:16Z
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

New patches and a rebase.

0001 - no changes, but the longer I go the more I'm certain this is
something we want to do.
0002- same as 0001

0003 -

Storing the restore function calls in the archive entry hogged a lot of
memory and made people nervous. This introduces a new function pointer that
generates those restore SQL calls right before they're written to disk,
thus reducing the memory load from "stats for every object to be dumped" to
just one object. Thanks to Nathan for diagnosing some weird quirks with
various formats.

0004 -

This replaces the query in the prepared statement with one that batches
them 100 relations at a time, and then maintains that result set until it
is consumed. It seems to have obvious speedups.


database pg14, 100k tables x 2 columns each:

0004: 34.5s with statistics, 25.04s without
0003: 42.23s with statistics, 24.29s without
0002: 42.25s with statistics, 23.17s without


Gory details:

PGSERVICE=benchmark14 time /usr/local/pgsql/bin/pg_dump --file=tip.run1.dump
5.45user 2.38system 0:34.50elapsed 22%CPU (0avgtext+0avgdata
912680maxresident)k
0inputs+2105736outputs (0major+245090minor)pagefaults 0swaps

PGSERVICE=benchmark14 time /usr/local/pgsql/bin/pg_dump --no-statistics
--file=tip.nostats.run1.dump
4.36user 2.05system 0:25.04elapsed 25%CPU (0avgtext+0avgdata
702488maxresident)k
0inputs+1643048outputs (0major+192512minor)pagefaults 0swaps

PGSERVICE=benchmark14 time /usr/local/pgsql/bin/pg_dump
--file=nobatch.run1.dump
5.60user 3.95system 0:42.23elapsed 22%CPU (0avgtext+0avgdata
902424maxresident)k
0inputs+2105672outputs (0major+242536minor)pagefaults 0swaps

PGSERVICE=benchmark14 time /usr/local/pgsql/bin/pg_dump --no-statistics
--file=nobatch-nostats.run1.dump
4.38user 2.13system 0:24.29elapsed 26%CPU (0avgtext+0avgdata
702292maxresident)k
48inputs+1642952outputs (0major+192515minor)pagefaults 0swaps

PGSERVICE=benchmark14 time /usr/local/pgsql/bin/pg_dump
--file=nostmtfn.run1.dump
6.01user 4.47system 0:42.25elapsed 24%CPU (0avgtext+0avgdata
1089784maxresident)k
0inputs+2106840outputs (0major+289407minor)pagefaults 0swaps

PGSERVICE=benchmark14 time /usr/local/pgsql/bin/pg_dump --no-statistics
--file=nostmtfn-nostats.run1.dump
4.35user 2.13system 0:23.17elapsed 27%CPU (0avgtext+0avgdata
690000maxresident)k
0inputs+1642952outputs (0major+189383minor)pagefaults 0swaps