Andrew Dunstan <andrew@xxxxxxxxxxxx> writes: > A client is testing a migration from 9.1 to 9.2, and has found that a > large number of queries run much faster if they use index-only scans. > However, the only way he has found to get such a plan is by increasing > the seq_page_cost to insanely high levels (3.5). Is there any approved > way to encourage such scans that's a but less violent than this? Is the pg_class.relallvisible estimate for the table realistic? They might need a few more VACUUM and ANALYZE cycles to get it into the neighborhood of reality, if not. Keep in mind also that small values of random_page_cost necessarily decrease the apparent advantage of index-only scans. If you think 3.5 is an "insanely high" setting, I wonder whether you haven't driven those numbers too far in the other direction to compensate for something else. regards, tom lane -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
