Re: index usage

[Ben <bench(at)silentmedia(dot)com>]

It's volatile, but it will always return an integer.

On Fri, 28 Jul 2006, Daniel Caune wrote:

> > De : pgsql-performance-owner(at)postgresql(dot)org [mailto:pgsql-performance-
> > owner(at)postgresql(dot)org] De la part de Ben
> > Envoyé : vendredi, juillet 28, 2006 15:21
> > À : pgsql-performance(at)postgresql(dot)org
> > Objet : [PERFORM] index usage
> >
> > I have a table with 37000 rows, an integer column, and an index on that
> > column. I've got a function that returns an integer. When I do a select
> > where I restrict that column to being equal to a static number, explain
> > tells me the index will be used. When I do the same thing but use the
> > function instead of a static number, explain shows me a full scan on the
> > table.
> >
> > I must be missing something, because my understanding is that the function
> > will be evaluated once for the statement and then collapsed into a static
> > number for the filtering. But the results of the explain seem to imply
> > that's not the case....?
>
> Is your function IMMUTABLE, STABLE or VOLATILE?
>
> --
> Daniel