On 2016-09-16 09:12:22 -0700, Jeff Janes wrote: > On Thu, Sep 15, 2016 at 7:23 AM, Andres Freund <and...@anarazel.de> wrote: > > One earlier question about this is whether that is actually a worthwhile > > goal. Are the speed and space benefits big enough in the general case? > > Could those benefits not be achieved in a more maintainable manner by > > adding a layer that uses a btree over hash(columns), and adds > > appropriate rechecks after heap scans? > > > > Note that I'm not saying that hash indexes are not worthwhile, I'm just > > doubtful that question has been explored sufficiently.
> I think that exploring it well requires good code. If the code is good, > why not commit it? Because getting there requires a lot of effort, debugging it afterwards would take effort, and maintaining it would also takes a fair amount? Adding code isn't free. I'm rather unenthused about having a hash index implementation that's mildly better in some corner cases, but otherwise doesn't have much benefit. That'll mean we'll have to step up our user education a lot, and we'll have to maintain something for little benefit. Andres -- Sent via pgsql-hackers mailing list (firstname.lastname@example.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers