Re: Why does row estimation on nested loop make no sense to me - Mailing list pgsql-general

Ok - I agree -

Can somebody help me understand where the row estimates come from on a nested-loop operation in postgres then?



----- Original Message -----
From: hubert depesz lubaczewski <depesz@depesz.com>
To: Jeff Amiel <becauseimjeff@yahoo.com>
Cc: "pgsql-general@postgresql.org" <pgsql-general@postgresql.org>
Sent: Saturday, May 18, 2013 3:39 AM
Subject: Re: [GENERAL] Why does row estimation on nested loop make no sense
 to me

Not sure if it helps, but it's apparently not a very rare thing.
Quick analysis on data from explain.depesz.com showed that > 12% of
plans with nested loop have such estimate.

Couple of examples:

http://explain.depesz.com/s/Qm4
http://explain.depesz.com/s/qmW
http://explain.depesz.com/s/qnG
http://explain.depesz.com/s/QO
http://explain.depesz.com/s/qov

...