try:
explain select when from notes where datetime_date(when) = 'now'::date;
-DEJ
> Tom Lane wrote:
>
> > In the meantime, a workaround is to call the function using its
> > builtin name:
> >
> > play=> create table notes (when datetime);
> > CREATE
> > play=> create index when_ndx3 on notes (datetime_date(when)
> date_ops);
> > CREATE
>
> Thanks, that helps - I can now index a datetime field by
> date.But the index
> doesn't appear to be used:
>
> db=> create index ndx3 on notes (datetime_date(when) date_ops);
> CREATE
> db=> vacuum analyze notes;
> VACUUM
> db=> explain select when from notes where when::date = 'now'::date;
> NOTICE: QUERY PLAN:
>
> Seq Scan on notes (cost=4330.37 size=43839 width=8)
>
> EXPLAIN
>
> So it appears that the optimizer doesn't like this index.
> (This is with
> version 6.4.2.)
> The table has about 90,000 rows, of which between 10 and 100
> might match a
> given date, so an index would really help.
>
> Am I missing something simple here? Thanks again for all your help.
>
> Andrew Merrill
>