On Mon, Sep 19, 2016 at 05:50:13PM +1200, Mark Kirkwood wrote: > >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. > > While I see the point of what you are saying here, I recall all previous > discussions about has indexes tended to go a bit like this: > > - until WAL logging of hash indexes is written it is not worthwhile trying > to make improvements to them > - WAL logging will be a lot of work, patches 1st please > > Now someone has done that work, and we seem to be objecting that because > they are not improved then the patches are (maybe) not worthwhile. I think > that is - essentially - somewhat unfair.
My understanding of hash indexes is that they'd be good for indexing random(esque) data (such as UUIDs or, well, hashes like shaX). If so then I've got a DB that'll be rather big that is the very embodiment of such a use case. It indexes such data for equality comparisons and runs on SELECT, INSERT and, eventually, DELETE. Lack of WAL and that big warning in the docs is why I haven't used it. Given the above, many lamentations from me that it wont be available for 9.6. :( When 10.0 comes I'd probably go to the bother of re-indexing with hash indexes. Andrew -- Sent via pgsql-hackers mailing list (firstname.lastname@example.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers