| From: | Robert Haas <robertmhaas(at)gmail(dot)com> |
|---|---|
| To: | Bruce Momjian <bruce(at)momjian(dot)us> |
| Cc: | Yuri Levinsky <yuril(at)celltick(dot)com>, pgsql-hackers(at)postgresql(dot)org |
| Subject: | Re: Hash partitioning. |
| Date: | 2013-06-25 15:02:40 |
| Message-ID: | CA+Tgmobispu8wk36b_tekTf2L2a=2Qncu6NbbDtampUoBhgTPw@mail.gmail.com |
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| Lists: | pgsql-hackers |
On Tue, Jun 25, 2013 at 9:21 AM, Bruce Momjian <bruce(at)momjian(dot)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
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