Re:

Ron Peterson wrote:
>
> Robert Deme wrote:
> >
> > Hello!!
> >
> > in flagship ( a variant of clipper for unix , http://www.wgs.com/) it is
> > an interesting statement "seek eval" ; it scans the index and for every
> > position it evaluates a block of code/ function until the function
> > return true .
> > is in postgresql an internal mechanism or a way to use the index when
> > selecting records with conditions like function(index_expression) =
> > value ?
>
> I'm not sure I understand the question.  There are a large number of
> functions built in to PostgreSQL that you can use in your queries.  Plus
> you can define your own functions in SQL, C, or other languages.  If
> you're talking about something else, maybe send an example.

I think he's asking about functional indexes. PostgreSQL does
support functional indexes. For example:

stocks=# create table test (field text);
CREATE
stocks=# create index k_test1 on test ( lower(field) );
CREATE

Then a

SELECT * FROM test WHERE lower(field) = 'mike'

would use the index (if the optimizer so chooses) to locate the
appropriate records.

Hope that helps,

Mike Mascari