Re: Deprecating Hash Indexes

On 15 October 2012 15:13, Robert Haas <robertmhaas@gmail.com> wrote:
> On Sun, Oct 14, 2012 at 9:45 AM, Simon Riggs <simon@2ndquadrant.com> wrote:
>> * Put WARNINGs in the docs against the use of hash indexes, backpatch
>> to 8.3. CREATE INDEX gives no warning currently, though Index Types
>> does mention a caution.
>
> I'd be in favor of adding such warnings to the documentation if they
> are not there already, and possibly even warning on CREATE INDEX ..
> USING hash().

Sounds like a good idea.

> I don't think I'd go so far as to say that we should
> imply that they'll be removed in a future release.  Given how deeply
> intertwined they are with the planner, I doubt that that will happen;
> and I think there is enough interest in the technology that it's
> likely to eventually be fixed.

Hash indexes aren't used in the planner. Hash joins use completely
separate code.

-- Simon Riggs                   http://www.2ndQuadrant.com/PostgreSQL Development, 24x7 Support, Training & Services