A dev has ran a VACUUM FULL command into our test database running PostgreSQL 9.5 (I know... goddamn!!!!)...
... after the Vacuum Full, some queries start using SEQ scans instead of indexes...
Does that happen because of the size of the table? The table that I'm referring to is 150MB big after the vacuum (Before was 1G)...
Yes, it is possible that sequential scans after vacuum full are cheaper than Index scans before vacuum full ? do you see improvement in query response times ?
How does the cost differ ?
Regards,
Venkata B N
Fujitsu Australia
Well... the response time was worst than when using index.. that's very weird... I've re-created the indexes now a ran ANALYZE and the query is using again the index.. just wanted understand what happened...
There you go.. Running ANALYZE made the difference. Whenever you execute VACUUM or VACUUM FULL make sure you execute ANALYZE so that latest stats are updated. Sorry, i should have mentioned this earlier.