Re: Hash partitioning. - Mailing list pgsql-hackers

From Robert Haas
Subject Re: Hash partitioning.
Date
Msg-id CA+Tgmobispu8wk36b_tekTf2L2a=2Qncu6NbbDtampUoBhgTPw@mail.gmail.com
Whole thread Raw
In response to Re: Hash partitioning.  (Bruce Momjian <bruce@momjian.us>)
Responses Re: Hash partitioning.
List pgsql-hackers
On Tue, Jun 25, 2013 at 9:21 AM, Bruce Momjian <bruce@momjian.us> wrote:
> On Tue, Jun 25, 2013 at 03:48:19PM +0300, Yuri Levinsky wrote:
>> Hi,
>>
>> Do we have any plans to implement Hash Partitioning, maybe I missing this
>> feature?
>
> You can do it by writing your own constraint and trigger functions that
> control the hashing.

Not really.  Constraint exclusion won't kick in for a constraint like
CHECK (hashme(a) % 16 == 3) and a WHERE clause of the form  a = 42.

Of course, since partitioning generally doesn't improve performance in
PostgreSQL anyway, it's not clear why you'd want to do this in the
first place.  But the fact that constraint exclusion won't work if you
do is kind of a knockout blow.

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



pgsql-hackers by date:

Previous
From: Robert Haas
Date:
Subject: Re: FILTER for aggregates [was Re: Department of Redundancy Department: makeNode(FuncCall) division]
Next
From: Bruce Momjian
Date:
Subject: Re: Hash partitioning.