Re: PG 10 - Trouble with overlap of range partition of two dimensions

On Nov 1, 2017 02:41, "Stephen Froehlich" <s(dot)froehlich(at)cablelabs(dot)com> wrote:

Hi Michael,

So if I'm reading this correctly, the proper way to do my use case is to
use partitions of partitions, right?

Or maybe reverse the order of the columns:

PARTITION BY RANGE (source_no, start_time)

--Stephen

-----Original Message-----
From: Michael Paquier [mailto:michael(dot)paquier(at)gmail(dot)com]
Sent: Tuesday, October 31, 2017 4:06 PM
To: Stephen Froehlich <s(dot)froehlich(at)cablelabs(dot)com>
Cc: pgsql-general(at)postgresql(dot)org
Subject: Re: [GENERAL] PG 10 - Trouble with overlap of range partition of
two dimensions

On Tue, Oct 31, 2017 at 8:36 PM, Stephen Froehlich <
s(dot)froehlich(at)cablelabs(dot)com> wrote:
> CREATE TABLE lotsa_data_20171027_src3 PARTITION OF lotsa_data
> FOR VALUES FROM ('2017-10-26 18:00:00-06', 3) TO ('2017-10-27
> 17:59:59.999-06', 3);
> ERROR: partition " lotsa_data_20171027_src1" would overlap partition
> "lotsa_data_20171027_src3"
>
> Why am I getting this error?

The answer is in the documentation:
https://www.postgresql.org/docs/devel/static/sql-createtable.html
The rules of such partitions is bound to row-wise comparisons. "For
example, given PARTITION BY RANGE (x,y), a partition bound FROM (1, 2) TO
(3, 4) allows x=1 with any y>=2, x=2 with any non-null y, and x=3 with any
y<4."

So in your example and by comparing with the docs, the first partition
allows start_time = '2017-10-26 18:00:00-06' with source_no >= 1, and the
second partition allows source_no >= 3 which overlaps with the first one.
--
Michael

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