To: Stefan Keller <sfkeller@gmail.com>
cc: Peter Geoghegan <peter@2ndquadrant.com>, pgsql-performance@postgresql.org
Subject: Re: Hash index use presently(?) discouraged since 2005: revive or
	bury it?
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Comments: In-reply-to Stefan Keller <sfkeller@gmail.com>
	message dated "Thu, 15 Sep 2011 01:03:46 +0200"
Date: Wed, 14 Sep 2011 19:40:18 -0400
Message-ID: <8905.1316043618@sss.pgh.pa.us>
From: Tom Lane <tgl@sss.pgh.pa.us>

Stefan Keller <sfkeller@gmail.com> writes:
> 2011/9/14 Tom Lane <tgl@sss.pgh.pa.us> writes:
>> (...) I think that
>> the current state of affairs is still what depesz said, namely that
>> there might be cases where they'd be a win to use, except the lack of
>> WAL support is a killer.  I imagine somebody will step up and do that
>> eventually.

> How much of work (in man days) do you estimate would this mean for
> someone who can program but has to learn PG internals first?

No idea ... I'm probably not the best person to estimate how long it
would take someone to get up to speed on the relevant internals,
but I'm sure that would take longer than actually doing the work.
While it's not a trivial task, I think it fits the definition of
"a small matter of programming": a piece of code whose anticipated
length is significantly greater than its complexity.

			regards, tom lane