On Wed, Nov 14, 2012 at 8:03 PM, Peter Geoghegan <peter@xxxxxxxxxxxxxxx> wrote: > On 15 November 2012 01:46, Andrew Dunstan <andrew@xxxxxxxxxxxx> wrote: >> It cuts both ways. I have used CTEs a LOT precisely because this behaviour >> lets me get better plans. Without that I'll be back to using the "offset 0" >> hack. > > Is the "OFFSET 0" hack really so bad? We've been telling people to do > that for years, so it's already something that we've effectively > committed to. IMSNHO, 'OFFSET 0' is completely unreadable black magic. I agree with Andrew: CTEs allow for manual composition of queries and can be the best tool when the planner is outsmarting itself. In the old days, we'd extract data to a temp table and join against that: CTE are essentially a formalization of that technique. I like things the way they are; if CTE are hurting your plan, that's an indication you're using them inappropriately. merlin -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
