Re: STABLE functions

Joachim Wieland <jwieland@kawo2.rwth-aachen.de> writes:
> I'm using 7.3.2 and encounter the problem that a SELECT query that uses
> a function with a constant argument is quite slow. The function is
> declared STABLE. Here's an example:

> SELECT ... FROM table WHERE col = f('xyz');

>> From what I read in the docs

> ( http://www.postgresql.org/docs/view.php?version=7.3&idoc=0&file=sql-createfunction.html )

> I thought that this function is only executed once when declared as
> STABLE,

You are mistaken.

If you'd declared it IMMUTABLE, then it would get constant-folded, but
that may or may not be suitable for your purpose.
        regards, tom lane