>
> >Net Virtual Mailing Lists wrote:
> >> Is there a way to create an index that would make this query be efficient
> >> and not perform a sequential scan?
> >>
> >> SELECT count(*) AS count,id FROM sometable GROUP BY id;
> >
> >Indexes cannot be used for retrieving results...
I'm not sure if it would improve performance at all, given the entire
table needs to be scanned anyway, but add a where clause "where id > 0"
should allow an index on id to be used.
Possibly a bit like speeding up "select max(id) from ..."
Someone who knows more about the internals of Postgis can prob comment on
the validity/idiocy of this suggestion :-)
Brent Wood