29.03.2024 11:59, Alexander Lakhin wrote:
But it looks like subselect is not the only test that can fail due to
vacuum instability. I see that create_index also suffers from cranky
ConditionalLockBufferForCleanup() (+if (rand() % 10 == 0)
return false; ), although it placed in parallel_schedule before
sanity_check, so this failure needs another explanation:
- QUERY PLAN
--------------------------------------------------------
- Index Only Scan using tenk1_thous_tenthous on tenk1
- Index Cond: (thousand < 2)
- Filter: (tenthous = ANY ('{1001,3000}'::integer[]))
-(3 rows)
+ QUERY PLAN
+--------------------------------------------------------------------------------------
+ Sort
+ Sort Key: thousand
+ -> Index Only Scan using tenk1_thous_tenthous on tenk1
+ Index Cond: ((thousand < 2) AND (tenthous = ANY
('{1001,3000}'::integer[])))
+(4 rows)
I think that deviation can be explained by the fact that cost_index() takes
baserel->allvisfrac (derived from pg_class.relallvisible) into account for
the index-only-scan case, and I see the following difference when a test
run fails:
relname | relpages | reltuples | relallvisible | indisvalid |
autovacuum_count | autoanalyze_count
----------------------+----------+-----------+---------------+------------+------------------+-------------------
- tenk1 | 345 | 10000 | 345 | |
0 | 0
+ tenk1 | 345 | 10000 | 305 | |
0 | 0
Best regards,
Alexander
