But why? The expression is not on the left side of the WHERE clause.
> Hello
>
> use a functional index
>
> http://www.postgresql.org/docs/8.4/interactive/indexes-expressional.html
>
> Regards
>
> Pavel Stehule
>
> 2011/8/8 - - <loh.law@hotmail.com>:
> > For a table where column col has an index, the query:
> > SELECT ... FROM ... WHERE col = MD5('')
> > doesn't seem to use an index but
> > SELECT ... FROM ... WHERE col = 'd41d8cd98f00b204e9800998ecf8427e'
> > does.
> >
> > Is this a gotcha?
> > I'm using PostgreSQL 8.4.8 on i686-pc-linux-gnu, compiled by GCC
> > gcc-4.5.real (Ubuntu/Linaro 4.5.2-8ubuntu4) 4.5.2, 32-bit
> >
> >
> >