Horton

Re: Statistics Import and Export

Ashutosh Bapat <ashutosh.bapat.oss@gmail.com>

View thread
From: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com>
To: Corey Huinker <corey.huinker@gmail.com>
Cc: Tom Lane <tgl@sss.pgh.pa.us>, Magnus Hagander <magnus@hagander.net>, Jeff Davis <pgsql@j-davis.com>, Stephen Frost <sfrost@snowman.net>, Matthias van de Meent <boekewurm+postgres@gmail.com>, Peter Smith <smithpb2250@gmail.com>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>, Tomas Vondra <tomas.vondra@enterprisedb.com>
Date: 2024-04-01T11:31:02Z
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 Corey,

Some more comments on v15.

+/*
+ * A more encapsulated version of can_modify_relation for when the the
+ * HeapTuple and Form_pg_class are not needed later.
+ */
+static void
+check_relation_permissions(Relation rel)

This function is used exactly at one place, so usually won't make much
sense to write a separate function. But given that the caller is so long,
this seems ok. If this function returns the cached tuple when permission
checks succeed, it can be used at the other place as well. The caller will
be responsible to release the tuple Or update it.

Attached patch contains a test to invoke this function on a view. ANALYZE
throws a WARNING when a view is passed to it. Similarly this function
should refuse to update the statistics on relations for which ANALYZE
throws a warning. A warning instead of an error seems fine.

+
+ const float4 min = 0.0;
+ const float4 max = 1.0;

When reading the validation condition, I have to look up variable values.
That can be avoided by directly using the values in the condition itself?
If there's some dependency elsewhere in the code, we can use macros. But I
have not seen using constant variables in such a way elsewhere in the code.

+ values[Anum_pg_statistic_starelid - 1] = ObjectIdGetDatum(relid);
+ values[Anum_pg_statistic_staattnum - 1] = Int16GetDatum(attnum);
+ values[Anum_pg_statistic_stainherit - 1] = PG_GETARG_DATUM(P_INHERITED);

For a partitioned table this value has to be true. For a normal table when
setting this value to true, it should at least make sure that the table has
at least one child. Otherwise it should throw an error. Blindly accepting
the given value may render the statistics unusable. Prologue of the
function needs to be updated accordingly.

I have fixed a documentation error in the patch as well. Please incorporate
it in your next patchset.
-- 
Best Wishes,
Ashutosh Bapat