Thread: cast affects use of indexes ?

cast affects use of indexes ?

From
Alex Vinogradovs
Date:
Guys,

I've got a table with an indexed column of a numeric user
type (implemented in C). When I run a select on that table
in a form of :

select * from sometable where column = 89464;

sequential scan is used...

When I rewrite the query to use cast like this :

select * from sometable where column = 89464::mytype;

bitmap index scan and bitmap heap scan are used.

Is it possible to make it work properly without
use of explicit casts ? Thanks!


Best regards,
Alex Vinogradovs





Re: cast affects use of indexes ?

From
Tom Lane
Date:
Alex Vinogradovs <AVinogradovs@clearpathnet.com> writes:
> Is it possible to make it work properly without
> use of explicit casts ? Thanks!

Read
http://www.postgresql.org/docs/8.3/static/xindex.html
particularly the discussion of cross-type index operators.

            regards, tom lane