Thread: [GENERAL] PG 10 - Trouble with overlap of range partition of two dimensions
[GENERAL] PG 10 - Trouble with overlap of range partition of two dimensions
From
Stephen Froehlich
Date:
So I have a table that has two fields I want to partition by:
CREATE TABLE lotsa_data (
start_time timestamp with time zone,
source_no integer,
counter integer)
PARTITION BY RANGE (start_time, source_no);
CREATE TABLE lotsa_data_20171027_src1 PARTITION OF lotsa_data
FOR VALUES FROM ('2017-10-26 18:00:00-06', 1) TO ('2017-10-27 17:59:59.999-06', 1);
(Works fine)
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? (Also, if I go “FROM (‘2017-10-26 00:00:00 UTC’) TO (‘2017-10-27 00:00:00 UTC’)” I also get overlap errors.
Thanks for your help …
--Stephen
Stephen Froehlich
Sr. Strategist, CableLabs®
s.froehlich@cablelabs.com
Tel: +1 (303) 661-3708
Re: [GENERAL] PG 10 - Trouble with overlap of range partition of two dimensions
From
Michael Paquier
Date:
On Tue, Oct 31, 2017 at 8:36 PM, Stephen Froehlich
<s.froehlich@cablelabs.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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Re: [GENERAL] PG 10 - Trouble with overlap of range partition of twodimensions
From
Stephen Froehlich
Date:
Hi Michael,
So if I'm reading this correctly, the proper way to do my use case is to use partitions of partitions, right?
--Stephen
-----Original Message-----
From: Michael Paquier [mailto:michael.paquier@gmail.com]
Sent: Tuesday, October 31, 2017 4:06 PM
To: Stephen Froehlich <s.froehlich@cablelabs.com>
Cc: pgsql-general@postgresql.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.froehlich@cablelabs.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
partitionbound 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'
withsource_no >= 1, and the second partition allows source_no >= 3 which overlaps with the first one.
--
Michael
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Re: [GENERAL] PG 10 - Trouble with overlap of range partition of two dimensions
From
Arjen Nienhuis
Date:
On Nov 1, 2017 02:41, "Stephen Froehlich" <s.froehlich@cablelabs.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.paquier@gmail.com]
Sent: Tuesday, October 31, 2017 4:06 PM
To: Stephen Froehlich <s.froehlich@cablelabs.com>
Cc: pgsql-general@postgresql.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.froehlich@cablelabs.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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