Horton

Re: Hash Indexes

Amit Kapila <amit.kapila16@gmail.com>

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From: Amit Kapila <amit.kapila16@gmail.com>
To: Greg Stark <stark@mit.edu>
Cc: Tom Lane <tgl@sss.pgh.pa.us>, Andres Freund <andres@anarazel.de>, Oskari Saarenmaa <os@ohmu.fi>, Robert Haas <robertmhaas@gmail.com>, Bruce Momjian <bruce@momjian.us>, Jeff Janes <jeff.janes@gmail.com>, pgsql-hackers <pgsql-hackers@postgresql.org>
Date: 2016-09-25T05:18:26Z
Lists: pgsql-hackers 
On Sat, Sep 24, 2016 at 10:49 PM, Greg Stark <stark@mit.edu> wrote:
> On Thu, Sep 22, 2016 at 3:23 AM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
>> But to kick the hash AM as such to the curb is to say
>> "sorry, there will never be O(1) index lookups in Postgres".
>
> Well there's plenty of halfway solutions for that. We could move hash
> indexes to contrib or even have them in core as experimental_hash or
> unlogged_hash until the day they achieve their potential.
>
> We definitely shouldn't discourage people from working on hash indexes
>

Okay, but to me it appears that naming it as experimental_hash or
moving it to contrib could discourage people or at the very least
people will be less motivated.  Thinking on those lines a year or so
back would have been a wise direction, but now when already there is
lot of work done (patches to make it wal-enabled, more concurrent and
performant, page inspect module are available) for hash indexes and
still more is in progress, that sounds like a step backward then step
forward.

-- 
With Regards,
Amit Kapila.
EnterpriseDB: http://www.enterprisedb.com

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.