Re: Postgres 8.1 choosing the larger index for an index scan

s anwar <sanwar@gmail.com> writes:
> I have a very simple setup. I have one table with ~65000 tuples consuming
> ~8500 pages (reltuples and relpages as per pg_class). I have defined two
> indices on table, t1_id1 which indexes "t1(id1)" which consumes 194 pages;
> and t1_id1_v1 which indexes "t1(id1) where id1=3D9999" which consumes 4 pag=
> es.
> When I run an "explain select * from t1 where id1=3D9999;" it chooses to
> index-scan the t1_id1 index instead of t1_id1_v1 index, even though that th=
> e
> where-clause uses an equal comparison and there is a smaller index defined
> on t1 limited to the value of id1 to 9999.

What's the datatype of id1?  There are some limitations in the current
code about recognizing cross-type WHERE conditions ...

            regards, tom lane