Horton

Re: Hash Indexes

Andres Freund <andres@anarazel.de>

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From: Andres Freund <andres@anarazel.de>
To: Robert Haas <robertmhaas@gmail.com>
Cc: Peter Geoghegan <pg@heroku.com>, Jesper Pedersen <jesper.pedersen@redhat.com>, Amit Kapila <amit.kapila16@gmail.com>, Jeff Janes <jeff.janes@gmail.com>, Mithun Cy <mithun.cy@enterprisedb.com>, pgsql-hackers <pgsql-hackers@postgresql.org>
Date: 2016-09-30T00:16:27Z
Lists: pgsql-hackers 
On 2016-09-29 20:14:40 -0400, Robert Haas wrote:
> On Thu, Sep 29, 2016 at 8:07 PM, Peter Geoghegan <pg@heroku.com> wrote:
> > On Wed, Sep 28, 2016 at 8:06 PM, Andres Freund <andres@anarazel.de> wrote:
> >> On 2016-09-28 15:04:30 -0400, Robert Haas wrote:
> >>> Andres already
> >>> stated that he things working on btree-over-hash would be more
> >>> beneficial than fixing hash, but at this point it seems like he's the
> >>> only one who takes that position.
> >>
> >> Note that I did *NOT* take that position. I was saying that I think we
> >> should evaluate whether that's not a better approach, doing some simple
> >> performance comparisons.
> >
> > I, for one, agree with this position.
>
> Well, I, for one, find it frustrating.  It seems pretty unhelpful to
> bring this up only after the code has already been written.

I brought this up in person at pgcon too.

Commits

  1. Remove _hash_wrtbuf() in favor of calling MarkBufferDirty().

  2. Fix race introduced by 6d46f4783efe457f74816a75173eb23ed8930020.

  3. Improve hash index bucket split behavior.

  4. Reduce pinning and buffer content locking for btree scans.