Horton

Re: Statistics Import and Export

Jeff Davis <pgsql@j-davis.com>

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From: Jeff Davis <pgsql@j-davis.com>
To: Corey Huinker <corey.huinker@gmail.com>
Cc: Matthias van de Meent <boekewurm+postgres@gmail.com>, Bruce Momjian <bruce@momjian.us>, 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>, Tomas Vondra <tomas.vondra@enterprisedb.com>, alvherre@alvh.no-ip.org
Date: 2024-07-23T00:45:50Z
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.

On Mon, 2024-07-22 at 12:05 -0400, Corey Huinker wrote:
> Attached is v24, incorporating Jeff's feedback - looping an arg data
> structure rather than individually checking each param type being the
> biggest of them.
> 

Thank you for splitting up the patches more finely.

v24-0001:

  * pg_set_relation_stats(): the warning: "cannot export statistics
prior to version 9.2" doesn't make sense because the function is for
importing. Reword.

  * I really think there should be a transactional option, just another
boolean, and if it has a default it should be true. This clearly has
use cases for testing plans, etc., and often transactions will be the
right thing there. This should be a trivial code change, and it will
also be easier to document.

  * The return type is documented as 'void'? Please change to bool and
be clear about what true/false returns really mean. I think false means
"no updates happened at all, and a WARNING was printed indicating why"
whereas true means "all updates were applied successfully".

  * An alternative would be to have an 'error_ok' parameter to say
whether to issue WARNINGs or ERRORs. I think we already discussed that
and agreed on the boolean return, but I just want to confirm that this
was a conscious choice?

  * tests should be called stats_import.sql; there's no exporting going
on

  * Aside from the above comments and some other cleanup, I think this
is a simple patch and independently useful. I am looking to commit this
one soon.

v24-0002:

  * Documented return type is 'void'

  * I'm not totally sure what should be returned in the event that some
updates were applied and some not. I'm inclined to say that true should
mean that all updates were applied -- otherwise it's hard to
automatically detect some kind of typo.

  * Can you describe your approach to error checking? What kinds of
errors are worth checking, and which should we just put into the
catalog and let the planner deal with?

  * I'd check stakindidx at the time that it's incremented rather than
summing boolean values cast to integers.

v24-0003:

  * I'm not convinced that we should continue when a stat name is not
text. The argument for being lenient is that statistics may change over
time, and we might have to ignore something that can't be imported from
an old version into a new version because it's either gone or the
meaning has changed too much. But that argument doesn't apply to a
bogus call, where the name/value pairs get misaligned or something.

Regards,
	Jeff Davis