Horton

Re: Statistics Import and Export

Bertrand Drouvot <bertranddrouvot.pg@gmail.com>

View thread
From: Bertrand Drouvot <bertranddrouvot.pg@gmail.com>
To: Corey Huinker <corey.huinker@gmail.com>
Cc: Stephen Frost <sfrost@snowman.net>, Matthias van de Meent <boekewurm+postgres@gmail.com>, 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>
Date: 2024-03-11T08:50:33Z
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.

Hi,

On Fri, Mar 08, 2024 at 01:35:40AM -0500, Corey Huinker wrote:
> Anyway, here's v7. Eagerly awaiting feedback.

Thanks!

A few random comments:

1 ===

+        The purpose of this function is to apply statistics values in an
+        upgrade situation that are "good enough" for system operation until

Worth to add a few words about "influencing" the planner use case?

2 ===

+#include "catalog/pg_type.h"
+#include "fmgr.h"

Are those 2 needed?

3 ===

+       if (!HeapTupleIsValid(ctup))
+               elog(ERROR, "pg_class entry for relid %u vanished during statistics import",

s/during statistics import/when setting statistics/?

4 ===

+Datum
+pg_set_relation_stats(PG_FUNCTION_ARGS)
+{
.
.
+       table_close(rel, ShareUpdateExclusiveLock);
+
+       PG_RETURN_BOOL(true);

Why returning a bool? (I mean we'd throw an error or return true).

5 ===

+ */
+Datum
+pg_set_attribute_stats(PG_FUNCTION_ARGS)
+{

This function is not that simple, worth to explain its logic in a comment above?

6 ===

+       if (!HeapTupleIsValid(tuple))
+       {
+               relation_close(rel, NoLock);
+               PG_RETURN_BOOL(false);
+       }
+
+       attr = (Form_pg_attribute) GETSTRUCT(tuple);
+       if (attr->attisdropped)
+       {
+               ReleaseSysCache(tuple);
+               relation_close(rel, NoLock);
+               PG_RETURN_BOOL(false);
+       }

Why is it returning "false" and not throwing an error? (if ok, then I think
we can get rid of returning a bool).

7 ===

+        * If this relation is an index and that index has expressions in
+        * it, and the attnum specified

s/is an index and that index has/is an index that has/?

Regards,

-- 
Bertrand Drouvot
PostgreSQL Contributors Team
RDS Open Source Databases
Amazon Web Services: https://aws.amazon.com