Re: (9.1) btree_gist support for searching on "not equals"

On Fri, Jul 16, 2010 at 1:19 AM, Jeff Davis <pgsql(at)j-davis(dot)com> wrote:
> Thank you for the review.
>
> On Mon, 2010-07-12 at 17:17 +0900, Itagaki Takahiro wrote:
>> (1) Exclusion constraints support for operators where "x <operator> x"
>> is false (tiny patch)
>> https://commitfest.postgresql.org/action/patch_view?id=307
>> (2) btree_gist support for searching on <> ("not equals")
>> https://commitfest.postgresql.org/action/patch_view?id=308
>>
>> Those patches should be committed at once because (2) requires (1) to work
>> with EXCLUDE constraints. Also, (1) has no benefits without (2) because we
>> have no use cases for <> as an index-able operator. Both patches are very
>> simple and small, and worked as expected both "WHERE <>" and EXCLUDE
>> constraints cases.
>
> It appears that Tom already committed (1).
>
>> I'd like to ask you to write additional documentation about btree_gist [1]
>> that the module will be more useful when it is used with exclusion
>> constraints together. Without documentation, no users find the usages.
>
> Good idea, new patch attached.

It seems pretty odd to define a constant called
BTNotEqualStrategyNumber in contrib/btree_gist. Shouldn't we either
call this something else, or define it in access/skey.h? Considering
that there seem to be some interesting gymnastics being done with
BTMaxStrategyNumber, I'd vote for the former. Maybe just
BtreeGistNotEqualStrategyNumber?

--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise Postgres Company