From: | Fujii Masao <masao(dot)fujii(at)gmail(dot)com> |
---|---|
To: | Alvaro Herrera <alvherre(at)2ndquadrant(dot)com> |
Cc: | Claudio Freire <klaussfreire(at)gmail(dot)com>, Heikki Linnakangas <hlinnakangas(at)vmware(dot)com>, Andres Freund <andres(at)2ndquadrant(dot)com>, Robert Haas <robertmhaas(at)gmail(dot)com>, Pg Hackers <pgsql-hackers(at)postgresql(dot)org> |
Subject: | Re: Minmax indexes |
Date: | 2014-07-11 06:21:35 |
Message-ID: | CAHGQGwFAP7c7+-sN0SebmURdOTjXSKA8YxTQM4WuF4bby_tPJg@mail.gmail.com |
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On Thu, Jul 10, 2014 at 6:16 AM, Alvaro Herrera
<alvherre(at)2ndquadrant(dot)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
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