Re: select distinct and index usage

David Wilson wrote:
> On another table in the same database with a much smaller number of
> total rows (~15m rows), I have the exact same situation- but in this
> case the index on the datestamp column *is* used:
>
Have you run ANALYZE on both tables?

It might be worth increasing the stats collected on the datestamp column
(or all columns in the table), re-running ANALYZE on the table, and
seeing what happens.

Also, is there any chance that that's a lot more variation in datestamp
values in your problem table than the one where the index is used?

--
Craig Ringer