Re: Selectivity of "=" (Re: [HACKERS] Index not used on simple se lect)

> Yes, I think we index nulls.  What are partial indexes?
> 
A create index statement that accepts a where condition. All
rows that satisfy the where condition are indexed, others not.
This needs intelligence in the optimizer.

This was in postgresql code some time ago, but was removed
for some reason I don't remember.

Example: create index ax0 on a (id) where id is not null;

Andreas