Marc Boucher <pgml@gmx.net> writes:
>> Index scans aren't always faster than sequential scans.
> I know that, but I've some comparisons with other queries. And someone
> advised me to try "set enable_seqscan=off;". It takes 50-60% (after
> checking right now) less to use the index. Unfortunately I can't use this
> setting, the query being part of a larger query (joins), and the time
> gained on this particular index is partially lost on the joins.
A less brute-force way of encouraging the planner to use indexscans is
to reduce the random_page_cost setting. It defaults to 4 but many
people find that values nearer 2 are more representative of what happens
in their environments.
regards, tom lane
