Re: On partitioning

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. It is used in combination with range or hash partitioning as composite partitioning. So, perhaps we need not worry about that.

Regards,
Amit