Message-ID: <54054CF3.4040205@2ndquadrant.com>
Date: Tue, 02 Sep 2014 12:52:03 +0800
From: Craig Ringer <craig@2ndquadrant.com>
Organization: 2nd Quadrant
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To: Andres Freund <andres@2ndquadrant.com>,
 Hannu Krosing <hannu@2ndQuadrant.com>
CC: Tom Lane <tgl@sss.pgh.pa.us>, Alvaro Herrera <alvherre@2ndquadrant.com>,
 Greg Stark <stark@mit.edu>, Pg Hackers <pgsql-hackers@postgresql.org>
Subject: Re: On partitioning
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 <21834.1409332516@sss.pgh.pa.us> <5400C280.8070305@2ndQuadrant.com>
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On 09/01/2014 11:52 PM, Andres Freund wrote:
> I personally think that implementing cross partition indexes has a low
> enough cost/benefit ratio that I doubt it's wise to tackle it anytime
> soon.

UNIQUE constraints on partitioned tables (and thus foreign key
constraints pointing to partitioned tables) are a pretty big limitation
at the moment.

That said, the planner may well be able to use the greater knowledge of
the partitioned table structure to do this implictly, as it knows that a
unique index on the partition is also implicitly unique across
partitions on the partitioning key.

-- 
 Craig Ringer                   http://www.2ndQuadrant.com/
 PostgreSQL Development, 24x7 Support, Training & Services


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