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: 2024-08-02T06:44:54Z
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 Sat, 2024-07-27 at 21:08 -0400, Corey Huinker wrote:
> 
> > I don't like the idea of mixing statistics and control parameters
> > in
> > the same list.
> > 
> 
> 
> There's no way around it, at least now we need never worry about a
> confusing order for the parameters in the _restore_ functions because
> they can now be in any order you like.

Perhaps I was not precise enough when I said "control" parameters.
Mainly what I was worried about is trying to take parameters that
control things like transaction behavior (in-place vs mvcc), and
pg_dump should not be specifying that kind of thing. A parameter like
"version" is specified by pg_dump anyway, so it's probably fine the way
you've done it.

> SELECT pg_catalog.pg_set_attribute_stats(
>     relation => 'stats_import.test'::regclass::oid,
>     attname => 'arange'::name,
>     inherited => false::boolean,
>     null_frac => 0.5::real,
>     avg_width => 2::integer,
>     n_distinct => -0.1::real,
>     range_empty_frac => 0.5::real,
>     range_length_histogram => '{399,499,Infinity}'::text
>     );
>  pg_set_attribute_stats 
> ------------------------
>  
> (1 row)

I like it.

> and here is a restore function
> 
> -- warning: mcv cast failure
> SELECT *
> FROM pg_catalog.pg_restore_attribute_stats(
>     'relation', 'stats_import.test'::regclass::oid,
>     'attname', 'id'::name,
>     'inherited', false::boolean,
>     'version', 150000::integer,
>     'null_frac', 0.5::real,
>     'avg_width', 2::integer,
>     'n_distinct', -0.4::real,
>     'most_common_vals', '{2,four,3}'::text,
>     'most_common_freqs', '{0.3,0.25,0.05}'::real[]
>     );
> WARNING:  invalid input syntax for type integer: "four"
>  row_written |          stats_applied           |          
>  stats_rejected            | params_rejected 
> -------------+----------------------------------+--------------------
> ------------------+-----------------
>  t           | {null_frac,avg_width,n_distinct} |
> {most_common_vals,most_common_freqs} | 
> (1 row)

I think I like this, as well, except for the return value, which seems
like too much information and a bit over-engineered. Can we simplify it
to what's actually going to be used by pg_upgrade and other tools?

> Attached is v25.

I believe 0001 and 0002 are in good shape API-wise, and I can start
getting those committed. I will try to clean up the code in the
process.

Regards,
	Jeff Davis