Re: Improper processing of random values in sub-queries

David Newall <davidn-postgres@rebel.net.au> writes:
> NOW CONSIDER the following query, executed using psql:

> SELECT i, j from (
>   SELECT i, ((i + 18 * random())::integer % 20 + 1) AS j FROM data
> ) foo WHERE j = 15;

Hmph.  Evidently the planner should refuse to flatten subselects that
have volatile functions in their output list (and perhaps anywhere
else??).  This will probably make some people unhappy, but I see no
other fix.

I assume though that this is a made-up example and is not the case
that's really troubling you.  What is the actual problem you are looking
at?

            regards, tom lane