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From: Tom Lane <tgl@sss.pgh.pa.us>
To: John Papandriopoulos <dr.jpap@gmail.com>
Cc: pgsql-performance@postgresql.org
Subject: Re: Query-plan for partitioned UPDATE/DELETE slow and swaps vmem compared to SELECT
Date: Sun, 05 Dec 2010 15:14:38 -0500
Message-ID: <29662.1291580078@sss.pgh.pa.us> (raw)
In-Reply-To: <26275.1291568163@sss.pgh.pa.us>
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	<26275.1291568163@sss.pgh.pa.us>

I wrote:
> You could get rid of the memory growth, at the cost of a lot of
> tree-copying, by doing each child plan step in a discardable memory
> context.  I'm not sure that'd be a win for normal sizes of inheritance
> trees though --- you'd need to copy the querytree in and then copy the
> resulting plantree out again, for each child.  (Hm, but we're doing the
> front-end copy already ...)

That worked better than I thought it would --- see
http://git.postgresql.org/gitweb?p=postgresql.git;a=commitdiff;h=d1001a78ce612a16ea622b558f5fc2b68c4...
I'm not intending to back-patch this, but it ought to apply cleanly to
9.0.x if you want it badly enough to carry a local patch.

			regards, tom lane



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