Horton

Re: Hash Indexes

Geoff Winkless <pgsqladmin@geoff.dj>

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From: Geoff Winkless <pgsqladmin@geoff.dj>
To: Robert Haas <robertmhaas@gmail.com>
Cc: Bruce Momjian <bruce@momjian.us>, Andres Freund <andres@anarazel.de>, Jeff Janes <jeff.janes@gmail.com>, Amit Kapila <amit.kapila16@gmail.com>, pgsql-hackers <pgsql-hackers@postgresql.org>
Date: 2016-09-21T19:44:15Z
Lists: pgsql-hackers 
On 21 September 2016 at 13:29, Robert Haas <robertmhaas@gmail.com> wrote:
> I'd be curious what benefits people expect to get.

An edge case I came across the other day was a unique index on a large
string: postgresql popped up and told me that I couldn't insert a
value into the field because the BTREE-index-based constraint wouldn't
support the size of string, and that I should use a HASH index
instead. Which, of course, I can't, because it's fairly clearly
deprecated in the documentation...

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.