From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
---|---|
To: | Kenneth Marshall <ktm(at)rice(dot)edu> |
Cc: | Hannu Krosing <hannu(at)2ndQuadrant(dot)com>, Asko Oja <ascoja(at)gmail(dot)com>, Jeff Davis <pgsql(at)j-davis(dot)com>, pgsql-hackers(at)postgresql(dot)org |
Subject: | Re: [PATCHES] updated hash functions for postgresql v1 |
Date: | 2009-10-28 19:57:12 |
Message-ID: | 4236.1256759832@sss.pgh.pa.us |
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Lists: | pgsql-hackers |
Kenneth Marshall <ktm(at)rice(dot)edu> writes:
> On Wed, Oct 28, 2009 at 03:31:17PM -0400, Tom Lane wrote:
>> Hash indexes are so far from being production-grade that this argument
>> is not significant.
> In addition that change from 8.3 -> 8.4 to store only the hash and not
> the value in the index means that a reindex would be required in any event.
Indeed, and I fully expect there will be some more on-disk format
changes required before we get to the point where hash indexes are
actually interesting for production. If we start insisting that they
be in-place-upgradable now, we will pretty much guarantee that they
never become useful enough to justify the restriction :-(
(As examples, the hash bucket size probably needs revisiting,
and we ought to think very hard about whether we shouldn't switch
to 64-bit hash values. And that's not even considering some of the
more advanced suggestions that have been made.)
regards, tom lane
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