Re: INET datatype and '<<' operator results in bad row estimate

Mike Porter <mike@udel.edu> writes:
> Postgres version: 9.3.4
> Note: This behavior appears to have been fixed in 9.4-beta1.  I am
> reporting it in case it can be fixed in 9.3.x.  Perhaps it should be
> mentioned in the 9.4.x release notes (or did I miss it?)

Before 9.4, inet<<inet had no selectivity estimator at all, so you got
a default selectivity estimate of 0.5.  In 9.4 there is an estimator
function, but it's only a stub returning a constant estimate of 0.001;
so that makes this example better but only by luck.  There's some work in
progress to replace the stub with real selectivity estimation, but it
won't appear in any release before 9.5:

http://www.postgresql.org/message-id/flat/CAE2gYzwNBfGe9+1RP4UU6be9q2_m7Bfe6T18JgBSV4qJrkmxEQ@mail.gmail.com

If you're interested, please help test that patch.

            regards, tom lane