Re: Why is plan (and performance) different on partitioned table? - Mailing list pgsql-performance

From Tom Lane
Subject Re: Why is plan (and performance) different on partitioned table?
Date
Msg-id 22530.1146538756@sss.pgh.pa.us
Whole thread Raw
In response to Why is plan (and performance) different on partitioned table?  ("Mark Liberman" <mliberman@mixedsignals.com>)
Responses Re: Why is plan (and performance) different on partitioned table?
List pgsql-performance
"Mark Liberman" <mliberman@mixedsignals.com> writes:
> I have recently implemented table partitioning in our postgres 8.1 db. =
> Upon analyzing query performance, I have realized that, even when only a =
> single one of the "partitions" has to be scanned, the plan is =
> drastically different, and performs much worse, when I query against the =
> master table (uses merge join), vs. a direct query against the partition =
> directly (uses a hash join).  The majority of our queries only access a =
> single partition.

Joins against partitioned tables suck in 8.1 :-(.  There is code in CVS
HEAD to improve this, but it didn't get done in time for 8.1.

            regards, tom lane

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