I looked into Maxim Boguk's complaint here:
http://archives.postgresql.org/pgsql-general/2009-02/msg01226.php
in which the planner preferred to use an index despite the column
being searched on being a lower-order column in that index.
It turns out that the reason the planner is preferring the
On Fri, 2009-02-27 at 13:25 -0500, Tom Lane wrote:
So apparently we need to rethink this, and derate the correlation effect
somehow when there are constraints on non-first columns. I'm not
entirely sure what the model ought to be. Thoughts?
This seems similar to the problem of estimating
