Re: To what extent should tests rely on VACUUM ANALYZE?
От | Tom Lane |
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Тема | Re: To what extent should tests rely on VACUUM ANALYZE? |
Дата | |
Msg-id | 3640269.1711647210@sss.pgh.pa.us обсуждение исходный текст |
Ответ на | Re: To what extent should tests rely on VACUUM ANALYZE? (Tomas Vondra <tomas.vondra@enterprisedb.com>) |
Ответы |
Re: To what extent should tests rely on VACUUM ANALYZE?
Re: To what extent should tests rely on VACUUM ANALYZE? |
Список | pgsql-hackers |
Tomas Vondra <tomas.vondra@enterprisedb.com> writes: > Yeah. I think it's good to design the data/queries in such a way that > the behavior does not flip due to minor noise like in this case. +1 > But I'm a bit confused - how come the estimates do change at all? The > analyze simply fetches 30k rows, and tenk only has 10k of them. So we > should have *exact* numbers, and it should be exactly the same for all > the analyze runs. So how come it changes like this? It's plausible that the VACUUM ANALYZE done by test_setup fails ConditionalLockBufferForCleanup() sometimes because of concurrent activity like checkpointer writes. I'm not quite sure how we get from that to the observed symptom though. Maybe the VACUUM needs DISABLE_PAGE_SKIPPING? regards, tom lane
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