Kyle <kyle(at)actarg(dot)com> writes:
> The fourth "select" uses a regular subquery. It gives the error:
> psql:datbug.sql:44: ERROR: Sub-SELECT uses un-GROUPed attribute
> pay_req.wdate from outer query
This appears to work correctly in current sources. In 7.0.* and before
grouped views do not work very well, because the rewriter effectively
expands them in-line, thus converting your outer query into a grouped
query (or making it not work at all, if it was already grouped :-().
See related bug report just a few minutes ago on pgsql-bugs.
regards, tom lane