Collect per-relation and per-database vacuum statistics

[Alena0704]

Teach lazy vacuum to accumulate a set of counters for every vacuumed heap relation and index, and deliver them to the statistics collector with a new PGSTAT_MTYPE_VACSTATS message:

• tuples_deleted and dead_tuples (dead but not yet removable);
• the page counterparts: pages_deleted (heap truncation / index page deletion) and dead_pages;
• pages_frozen and pages_all_visible set by vacuum, which show whether vacuum is actually freezing tuples and keeping the visibility map up to date;
• wraparound_vacuum_count: runs that the freeze table age escalated to a full-table scan, which cannot skip pages through the visibility map. This release has no autovacuum for user tables, so a manual VACUUM is the only thing that ever advances relfrozenxid, and such an escalation is otherwise invisible. Note the freeze limits are clamped to their minimum values on a young cluster, making every relation match them; those runs are deliberately not reported as wraparound-driven ones;
• total_time of the vacuum, in microseconds.

The rev_all_frozen_pages/rev_all_visible_pages counters track how quickly the work of vacuum is undone: pages that lost their all-frozen/all-visible status. They are counted when ordinary DML clears the all-visible bit and are delivered with the regular relation statistics (PgStat_TableCounts), so they live directly in the relation/database entries of the collector rather than in the vacuum counters structure. rev_all_frozen_pages always stays zero here because the visibility map has no all-frozen bit in this release.

The counters are aggregated per relation (tables and indexes) and per database in the statistics collector.
They are exposed by the new vacuum_stats contrib extension, so no system catalog changes are needed: pg_stat_vacuum_tables, pg_stat_vacuum_indexes and pg_stat_vacuum_database show the local node, and the gp_stat_vacuum_* counterparts collect the master and all segments.

[Copilot]

Pull request overview

This PR adds end-to-end support for collecting per-relation (heap + index) and per-database vacuum counters in the stats collector via a new PGSTAT_MTYPE_VACSTATS message, and exposes them through a new vacuum_stats contrib extension (including Greenplum-wide gp_stat_vacuum_* views).

Changes:

• Extend pgstat infrastructure to carry and accumulate new vacuum/run counters (including “revoked all-visible” page counters).
• Teach lazy vacuum and heap DML paths to populate and report the new counters.
• Add the contrib/vacuum_stats extension plus regression/TAP/isolation tests and wire them into CI.

Reviewed changes

Copilot reviewed 18 out of 18 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
src/test/isolation/specs/vacuum-extending-in-repetable-read.spec	New isolation test exercising dead-tuples vs deleted-tuples behavior under REPEATABLE READ snapshot.
src/test/isolation/isolation_schedule	Adds the new isolation test to the schedule (but with a spelling typo in the test name).
src/test/isolation/expected/vacuum-extending-in-repetable-read.out	Expected output for the new isolation test (currently appears inconsistent/malformed).
src/include/pgstat.h	Adds PGSTAT_MTYPE_VACSTATS, PgStat_VacuumStats, revocation counters, and new reporting macros/API.
src/backend/postmaster/pgstat.c	Implements VACSTATS message send/receive and accumulation into rel/db entries; initializes/reset paths for new counters.
src/backend/commands/vacuumlazy.c	Tracks and reports new per-vacuum counters for heap and indexes; adds elapsed-time measurement and page counters.
src/backend/access/heap/heapam.c	Increments “revoked all-visible” counters when heap DML clears visibility-map all-visible bits.
contrib/vacuum_stats/vacuum_stats.control	New extension control file.
contrib/vacuum_stats/vacuum_stats.c	C accessor functions for rel/db vacuum counters (and revocation counters).
contrib/vacuum_stats/vacuum_stats--1.0.sql	Defines SQL functions and views (pg_stat_vacuum_*, gp_stat_vacuum_*) and grants.
contrib/vacuum_stats/sql/vacuum_stats.sql	pg_regress smoke test for the extension and views.
contrib/vacuum_stats/expected/vacuum_stats.out	Expected output for pg_regress smoke test.
contrib/vacuum_stats/t/001_vacuum_statistics.pl	TAP test covering table/index/db scenarios plus restart/crash-reset behavior.
contrib/vacuum_stats/README.md	Documentation for motivation, counters, tests, views, and usage.
contrib/vacuum_stats/Makefile	Build + installcheck + TAP targets for the new extension.
contrib/vacuum_stats/.gitignore	Ignores generated test directories.
contrib/Makefile	Adds vacuum_stats to contrib build.
.github/workflows/build-gpdb.yml	Adds isolation installcheck job and runs contrib/vacuum_stats installcheck + TAP in CI.

Suppressed comments (2)

src/test/isolation/expected/vacuum-extending-in-repetable-read.out:42

• This stats row conflicts with the preceding wait condition (dead_tuples=100). After the first VACUUM while the REPEATABLE READ snapshot is held, dead_tuples should be 100 and tuples_deleted should still be 0; the expected output currently shows the opposite and also appears to omit the pages_frozen column value. Please regenerate/fix the expected output for this step.

relname        tuples_deleted dead_tuples    pages_frozen   

test_vacuum_stat_isolation0              100            0              

src/test/isolation/expected/vacuum-extending-in-repetable-read.out:62

• The final stats print also looks malformed (relname concatenated with the first numeric value and missing the pages_frozen column value). If the intent is to show the state after the second VACUUM, the row should have separate columns for relname, tuples_deleted, dead_tuples, and pages_frozen. Regenerate the expected output so it matches the query output exactly.

relname        tuples_deleted dead_tuples    pages_frozen   

test_vacuum_stat_isolation100            100            0              

---

💡 Add a code-review agent skill or configure MCP servers for context-aware, tailored reviews. Learn more in the docs.