Re: Optimizing queries

Patrice Beliveau <pbeliveau(at)avior(dot)ca> writes:
>>> SELECT * FROM TABLE
>>> WHERE TABLE.COLUMN1=something
>>> AND TABLE.COLUMN2=somethingelse
>>> AND function(TABLE.COLUMN3,TABLE.COLUMN4) > 0;

> I find out that the function process every row even if the row should be
> rejected as per the first or the second condition.
> ... I'm using version 8.1.3

PG 8.1 will not reorder WHERE clauses for a single table unless it has
some specific reason to do so (and AFAICT no version back to 7.0 or so
has done so either...) So there's something you are not telling us that
is relevant. Let's see the exact table schema (psql \d output is good),
the exact query, and EXPLAIN output for that query.

regards, tom lane