Re: seq scan in the case of max() on the primary key column - Mailing list pgsql-performance

From Greg Smith
Subject Re: seq scan in the case of max() on the primary key column
Date
Msg-id 4DFB9620.8030702@2ndQuadrant.com
Whole thread Raw
In response to Re: seq scan in the case of max() on the primary key column  (Shaun Thomas <sthomas@peak6.com>)
List pgsql-performance
On 06/17/2011 08:43 AM, Shaun Thomas wrote:
> It's a bit of a hack, but it's worked fine for us while we wait for
> the planner to catch up. :)

Right.  In situations where people can modify their application to
redirect MIN/MAX() calls over to directly query the individual
partitions, that's a great workaround.  Your function is the slickest
such solution I've seen for that, so filing it away in case this pops up
in that situation.

But if you can't touch the application code and just need it to work as
desired, you either need to use PostgreSQL 9.1 (not yet released) or
figure out how to backport that fix into an earlier version (not easy).
A babbled a bit about this specific case at
http://blog.2ndquadrant.com/en/2011/06/max-partitioning-with-min-pain.html
if anyone wants more information, or a specific simple test case to play
with.

--
Greg Smith   2ndQuadrant US    greg@2ndQuadrant.com   Baltimore, MD
PostgreSQL Training, Services, and 24x7 Support  www.2ndQuadrant.us
"PostgreSQL 9.0 High Performance": http://www.2ndQuadrant.com/books


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