Re: Very ineffective plan with merge join
Tom Lane <tgl@sss.pgh.pa.us>
From: Tom Lane <tgl@sss.pgh.pa.us>
To: "Kevin Grittner" <Kevin.Grittner@wicourts.gov>
Cc: "Pgsql Hackers" <pgsql-hackers@postgresql.org>, "Oleg Bartunov" <oleg@sai.msu.su>
Date: 2010-04-15T22:00:58Z
Lists: pgsql-hackers
"Kevin Grittner" <Kevin.Grittner@wicourts.gov> writes: > What's up with the sort of _accrged7200 (in the slower plan) taking > in 3.5 million rows and putting out 1 row? There's something there > I'm not understanding. It's under a merge join, so what probably happened is that the first row from that side had a larger key than any row from the other side. A mergejoin will never bother to look at the remaining rows in such a case. regards, tom lane