From: | Andres Freund <andres(at)anarazel(dot)de> |
---|---|
To: | Jeff Janes <jeff(dot)janes(at)gmail(dot)com> |
Cc: | Amit Kapila <amit(dot)kapila16(at)gmail(dot)com>, pgsql-hackers <pgsql-hackers(at)postgresql(dot)org> |
Subject: | Re: Hash Indexes |
Date: | 2016-09-16 18:38:08 |
Message-ID: | 20160916183808.7gz4uudb5mg5itxc@alap3.anarazel.de |
Views: | Raw Message | Whole Thread | Download mbox | Resend email |
Thread: | |
Lists: | pgsql-hackers |
On 2016-09-16 09:12:22 -0700, Jeff Janes wrote:
> On Thu, Sep 15, 2016 at 7:23 AM, Andres Freund <andres(at)anarazel(dot)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
From | Date | Subject | |
---|---|---|---|
Next Message | Jesper Pedersen | 2016-09-16 18:58:25 | Re: Hash Indexes |
Previous Message | Robert Haas | 2016-09-16 18:37:00 | Re: more parallel query documentation |