Kenneth Marshall <ktm@rice.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