Bret Hughes <bhughes@elevating.com> writes:
> and the rows resulting from the query are no longer sorted by log date.
> Is this a change since 7.2x?
Yes. 7.4 can use hashing instead of sorting to bring grouped rows
together.
> I can achieve the results I need by adding an order by clause identical
> to the group by but this seems counter intuitive since the rows have to
> be ordered anyway.
No they don't; you're making an assumption about the implementation that
is no longer warranted. The SQL spec doesn't require it either ...
output ordering is only guaranteed if you specify ORDER BY, per spec.
regards, tom lane