>> Hash indexes have been improved since 2005 - their performance was
>> improved quite a bit in 9.0. Here's a more recent analysis:
>
>> http://www.depesz.com/index.php/2010/06/28/should-you-use-hash-index/
>
> The big picture though is that we're not going to remove hash indexes,
> even if they're nearly useless in themselves
Well, if they provide 3x the performance of btree indexes on index creation,
I wouldn't call them "useless" just because they're not logged or they can't
be unique. In fact, I think the docs should specify that in index creation
they're actually better than btree (if, in fact, they are and the "depesz" test
is not a corner case).