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: Bruce Momjian <bruce@momjian.us>, jian he <jian.universality@gmail.com>, Matthias van de Meent <boekewurm+postgres@gmail.com>, Tom Lane <tgl@sss.pgh.pa.us>, Nathan Bossart <nathandbossart@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: 2024-11-26T22:11:42Z
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.

>
>
> Comments on 0003:
>
> * If we commit 0003, is it a useful feature by itself or does it
> require that we commit some or all of 0004-0014? Which of these need to
> be in v18?
>

Useful by itself.

0004 seems needed to me, unless we're fine with ~50% bloat in pg_class on a
new-upgraded system, or we think inplace update are on their way out.

0005 is basically theoretical, it is only needed if we change the default
relpages on partitioned tables.

0006-0011 are the vacuumdb things being debated now. I've reached out to
some of the people I spoke to at PgConf.eu to get them to chime in.

0012 is now moot as a similar patch was committed Friday.

0013 is a cleanup/optimization.

0014 is the --no-data flag, which has no meaning without 0004, but 0004 in
no way requires it.


>
> * Why does binary upgrade cause statistics to be dumped? Can you just
> make pg_upgrade specify the appropriate set of flags?
>

That decision goes back a ways, I tried to dig in the archives last night
but I was getting a Server Error on postgresql.org.

Today I'm coming up with
https://www.postgresql.org/message-id/267624.1711756062%40sss.pgh.pa.us
which is actually more about whether stats import should be the default
(consensus: yesyesyes), and the binary_upgrade test may have been because
binary_upgrade shuts off data section stuff, but table stats are in the
data section. Happy to review the decision.


> * It looks like appendNamedArgument() is never called with
> positional=true?
>

That is currently the case. Currently all params are called with name/value
pairs, but in the past we had leading positionals followed by the stat-y
parameters in name-value pairs. I'll be refactoring it to remove the
positonal=T/F argument, which leaves just a list of name-type pairs, and
thus probably reduces the urge to make it an array of structs.


> * It's pretty awkward to use an array of arrays of strings when an
> array of structs might make more sense.


That pattern was introduced here:
https://www.postgresql.org/message-id/4afa70edab849ff16238d1100b6652404e9a4d9d.camel%40j-davis.com
:)

I'll be rebasing (that's done) and refactoring 0003 to get rid of the
positional column, and moving 0014 next to 0003 because they touch the same
files.