Re: Minmax indexes

On Thu, Jul 10, 2014 at 6:16 AM, Alvaro Herrera
<alvherre@2ndquadrant.com> wrote:
> Claudio Freire wrote:
>
>> An aggregate to generate a "compressed set" from several values
>> A function which adds a new value to the "compressed set" and returns
>> the new "compressed set"
>> A function which tests if a value is in a "compressed set"
>> A function which tests if a "compressed set" overlaps another
>> "compressed set" of equal type
>>
>> If you can define different compressed sets, you can use this to
>> generate both min/max indexes as well as bloom filter indexes. Whether
>> we'd want to have both is perhaps questionable, but having the ability
>> to is probably desirable.
>
> Here's a new version of this patch, which is more generic the original
> versions, and similar to what you describe.

I've not read the discussion so far at all, but I found the problem
when I played with this patch. Sorry if this has already been discussed.

=# create table test as select num from generate_series(1,10) num;
SELECT 10
=# create index testidx on test using minmax (num);
CREATE INDEX
=# alter table test alter column num type text;
ERROR:  could not determine which collation to use for string comparison
HINT:  Use the COLLATE clause to set the collation explicitly.

Regards,

-- 
Fujii Masao