Re:

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.

DROP TABLE pie;

CREATE TABLE pie (
filling text,

slice float --size in degrees.
);

INSERT INTO pie
VALUES ('blackbird', 90);

INSERT INTO pie
VALUES ('blackbird', 45);

INSERT INTO pie
VALUES ('plum', 120);

SELECT filling, radians( slice ) AS size
FROM pie
WHERE radians( slice ) > 1;

________________________
Ron Peterson
rpeterson(at)yellowbank(dot)com