Horton

Re: Hash Indexes

Robert Haas <robertmhaas@gmail.com>

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From: Robert Haas <robertmhaas@gmail.com>
To: Amit Kapila <amit.kapila16@gmail.com>
Cc: Jesper Pedersen <jesper.pedersen@redhat.com>, Jeff Janes <jeff.janes@gmail.com>, Mithun Cy <mithun.cy@enterprisedb.com>, pgsql-hackers <pgsql-hackers@postgresql.org>
Date: 2016-12-02T18:43:07Z
Lists: pgsql-hackers 
On Fri, Dec 2, 2016 at 1:54 AM, Amit Kapila <amit.kapila16@gmail.com> wrote:
>>  I want to split when the average bucket
>> contains 10 pages worth of tuples.
>
> oh, I think what you mean to say is hack the code to bump fill factor
> and then test it.  I was confused that how can user can do that from
> SQL command.

Yes, that's why I said "hacking the fill factor up to 1000" when I
originally mentioned it.

Actually, for hash indexes, there's no reason why we couldn't allow
fillfactor settings greater than 100, and it might be useful.
Possibly it should be the default.  Not 1000, certainly, but I'm not
sure that the current value of 75 is at all optimal.  The optimal
value might be 100 or 125 or 150 or something like that.

-- 
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company

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.