Horton

Re: Statistics Import and Export

Corey Huinker <corey.huinker@gmail.com>

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From: Corey Huinker <corey.huinker@gmail.com>
To: jian he <jian.universality@gmail.com>
Cc: Jeff Davis <pgsql@j-davis.com>, Nathan Bossart <nathandbossart@gmail.com>, Bruce Momjian <bruce@momjian.us>, Matthias van de Meent <boekewurm+postgres@gmail.com>, Tom Lane <tgl@sss.pgh.pa.us>, 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: 2025-01-16T15:52:25Z
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.

>
> pg_dump --dbname=src2 --table=tenk1 --statistics-only --verbose > x.sql
> there no pg_restore_attribute_stats, pg_restore_relation_stats there
> for table tenk1.
> There aren't any statistics, should there be?
>

pg_restore_relation_stats: yes. looking into that.
pg_restore_attribute_stats: yes IF the table had been analyzed, no
otherwise.


> also should
> pg_dump --dbname=src2 --no-data --no-schema --table=tenk1
> dump the statistics? currently seems no.
>




> in doc/src/sgml/ref/pg_dump.sgml
> there are six options to control the main output now.
> --schema-only, --statistics-only, --data-only,
> --no-schema, --no-data, --no-statistics
> maybe we need spare one paragraph to explain the default behavior,
> and also have an example on it?
>

+1



> pg_dump --dbname=src2 --table=tenk1 --verbose > 1.sql
> seems the statistics dump (pg_restore_attribute_stats) is ordered by
> attribute name.
> should it make more sense to order by attnum?
>

For security reasons, we pull attribute statistics from pg_stats (
https://www.postgresql.org/docs/current/view-pg-stats.html) which does not
have attnum. The only reason we order the list is to ensure that dump
comparison tests match.



> getRelationStatistics
> typedef struct _relStatsInfo
> {
>     DumpableObject    dobj;
>     char            relkind;        /* 'r', 'v', 'c', etc */
>     bool            postponed_def;
> } RelStatsInfo;
> comment /* 'r', 'v', 'c', etc */
> Is it wrong?  there is no relkind='c'.
>

Yeah, I think 'c' should be an 'm' there.


> field postponed_def really deserves a comment.
>

Can do.


>
>
> we also need change
> enum dbObjectTypePriorities
> static const int dbObjectTypePriority[]
> ?
>

We'd need two entries, because that enum includes PRIO_PRE_DATA_BOUNDARY
and PRIO_POST_DATA_BOUNDARY, and statistics can either be in DATA or
POST_DATA.



>
>
> in dumpRelationStats, we can add Assert on it.
>     if (!fout->dopt->dumpStatistics)
>         return;
> Assert(dobj->dump & DUMP_COMPONENT_STATISTICS);
>
>
> I found out the owner's info is missing in the dumped content.
> for example, the line "Name: STATISTICS DATA tenk1_pkey;" missing owner
> info.
> not sure this is intended?


Good question. I'm not sure if we need it or not. If stats had an owner,
it'd be the owner of the relation.