| From: | Robert Haas <robertmhaas(at)gmail(dot)com> |
|---|---|
| To: | Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> |
| Cc: | Amit Langote <Langote_Amit_f8(at)lab(dot)ntt(dot)co(dot)jp>, Andres Freund <andres(at)2ndquadrant(dot)com>, Alvaro Herrera <alvherre(at)2ndquadrant(dot)com>, Bruce Momjian <bruce(at)momjian(dot)us>, Pg Hackers <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: On partitioning |
| Date: | 2014-12-08 18:55:20 |
| Message-ID: | CA+TgmoYk9aU44Z5YRWoV2V9raj=HMbJBfORYr9GzF4vShsGvDA@mail.gmail.com |
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| Lists: | pgsql-hackers |
On Sat, Dec 6, 2014 at 2:59 AM, Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> wrote:
>> I guess you could list or hash partition on multiple columns, too.
>
> How would you distinguish values in list partition for multiple
> columns? I mean for range partition, we are sure there will
> be either one value for each column, but for list it could
> be multiple and not fixed for each partition, so I think it will not
> be easy to support the multicolumn partition key for list
> partitions.
I don't understand. If you want to range partition on columns (a, b),
you say that, say, tuples with (a, b) values less than (100, 200) go
here and the rest go elsewhere. For list partitioning, you say that,
say, tuples with (a, b) values of EXACTLY (100, 200) go here and the
rest go elsewhere. I'm not sure how useful that is but it's not
illogical.
--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company
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