Re: sunquery and estimated rows
Tom Lane <tgl@sss.pgh.pa.us>
From: Tom Lane <tgl@sss.pgh.pa.us>
To: Rod Taylor <rbt@rbt.ca>
Cc: Markus Bertheau <twanger@bluetwanger.de>, Litao Wu <litaowu@yahoo.com>, Postgresql Performance <pgsql-performance@postgresql.org>
Date: 2004-04-19T02:16:53Z
Lists: pgsql-performance
Rod Taylor <rbt@rbt.ca> writes: >> It's the only way to prevent it from simplifying when you don't want it >> to. > I'm having a difficult time coming up with a circumstance where that is > beneficial except when stats are out of whack. Try trawling the archives --- I recall several cases in which people were using sub-selects for this purpose. In any case, I don't see the value of having the planner check to see if a sub-select is just a trivial arithmetic expression. The cases where people write that and expect it to be simplified are so few and far between that I can't believe it'd be a good use of planner cycles. regards, tom lane