Horton

Re: Statistics Import and Export

jian he <jian.universality@gmail.com>

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From: jian he <jian.universality@gmail.com>
To: Corey Huinker <corey.huinker@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: 2025-01-17T14:20:12Z
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

hi.

SELECT * FROM pg_catalog.pg_restore_relation_stats(
    'relation', 'public.tenk1_hundred'::regclass,
    'version', '180000'::integer,
    'relpages', '11'::integer,
    'reltuples', '10000'::real,
    'relallvisible', '0'::integer
);
dump and execute the above query generated a warning
WARNING:  missing lock for relation "tenk1_hundred" (OID 18431,
relkind i) @ TID (15,34)


in dumpRelationStats(Archive *fout, const RelStatsInfo *rsinfo)
{
    getAttStatsExportQuery(query, fout, dobj->namespace->dobj.name,
                           dobj->name);
    res = ExecuteSqlQuery(fout, query->data, PGRES_TUPLES_OK);
    appendAttStatsImport(out, fout, res);
    PQclear(res)
}
i think, getAttStatsExportQuery no need to join catalog pg_namespace.

for example, after getAttStatsExportQuery, query->data looks like:
SELECT c.oid::regclass AS relation,
        s.attname,s.inherited,
        current_setting('server_version_num') AS version,
        s.null_frac,
        s.avg_width,
        s.n_distinct,
        s.most_common_vals,
        s.most_common_freqs,
        s.histogram_bounds,
        s.correlation,
        s.most_common_elems,
        s.most_common_elem_freqs,
        s.elem_count_histogram,
        s.range_length_histogram,
        s.range_empty_frac,
        s.range_bounds_histogram
FROM pg_stats s JOIN pg_namespace n ON n.nspname = s.schemaname JOIN pg_class c
ON c.relname = s.tablename AND c.relnamespace = n.oid
WHERE s.schemaname = 'public'
AND s.tablename = 'varchar_tbl'
ORDER BY s.attname, s.inherited
-----------------------
The SELECT column list doesn't mention/use any of the pg_namespace columns.

```WHERE s.schemaname = 'public' AND s.tablename = 'varchar_tbl'``
" s.schemaname" combined with "s.tablename" will make sure that the
output is unique, at most one row.


i did a minor refactor about validation dumpData, dumpSchema,
dumpStatistics option.
I think it's more intuitive. first we process ``*only``option then
process no* option