Re: On partitioning

On Mon, Dec 8, 2014 at 11:01 AM, Amit Langote <Langote_Amit_f8(at)lab(dot)ntt(dot)co(dot)jp>
wrote:
> From: Amit Kapila [mailto:amit(dot)kapila16(at)gmail(dot)com]
> Sent: Saturday, December 06, 2014 5:00 PM
> To: Robert Haas
> Cc: Amit Langote; Andres Freund; Alvaro Herrera; Bruce Momjian; Pg Hackers
> Subject: Re: [HACKERS] On partitioning
>
> On Fri, Dec 5, 2014 at 10:03 PM, Robert Haas <robertmhaas(at)gmail(dot)com>
wrote:
> > On Tue, Dec 2, 2014 at 10:43 PM, Amit Langote
> > <Langote_Amit_f8(at)lab(dot)ntt(dot)co(dot)jp> wrote:
> >
> > > I wonder if your suggestion of pg_node_tree plays well here. This
then could be a list of CONSTs or some such... And I am thinking it's a
concern only for range partitions, no? (that is, a multicolumn partition
key)
> >
> > 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.
>
> Irrespective of difficulties of representing it using pg_node_tree, it
seems to me that multicolumn list partitioning is not widely used.

So I think it is better to be clear why we are not planning to
support it, is it that because it is not required by users or
is it due to the reason that code seems to be tricky or is it due
to both of the reasons. It might help us if anyone raises this
during the development of this patch or in general if someone
requests such a feature.

With Regards,
Amit Kapila.
EnterpriseDB: http://www.enterprisedb.com