Re: 8.4b1 regression?

"Eric B. Ridge" <ebr(at)tcdi(dot)com> writes:
> I loaded a copy of a production database into PG 8.4b1 and immediately
> saw that all of our queries were significantly slower compared to v8.1.

> Some investigation showed that the use of non-IMMUTABLE PL/PGSQL
> functions as view columns, when these views are joined with other
> views, cause the query to be planned poorly.

I think this is due to a change that was made in 8.2:

* Do not flatten subqueries that contain volatile functions in their
target lists (Jaime Casanova)

This prevents surprising behavior due to multiple evaluation of a
volatile function (such as random() or nextval()). It might cause
performance degradation in the presence of functions that are
unnecessarily marked as volatile.

The pre-8.2 behavior was unduly optimistic about the safety of
rearranging calls to volatile functions.

regards, tom lane