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Re: dynamic SQL - possible performance regression in 9.2

From: Josh Berkus <josh(at)agliodbs(dot)com>
To: pgsql-hackers(at)postgresql(dot)org
Subject: Re: dynamic SQL - possible performance regression in 9.2
Date: 2013-01-04 20:05:49
Message-ID: 50E7361D.8050907@agliodbs.com (view raw or flat)
Thread:
Lists: pgsql-hackers
> Next question is what people think about back-patching into 9.2 so as
> to eliminate the performance regression vs 9.1.  I believe this would
> be safe (although some care would have to be taken to put the added
> boolean fields into places where they'd not result in an ABI break).
> However it may not be worth the risk.  The 40% slowdown seen with
> Pavel's example seems to me to be an extreme corner case --- Dong's
> result of 8% slowdown is probably more realistic for normal uses
> of SPI_execute.  Might be better to just live with it in 9.2.
> Thoughts?

8% is a pretty serious regression, for those of us with applications
which do a lot of dynamic SQL.  As a reminder, many people do dynamic
SQL even in repetitive, performance-sensitive functions in order to
avoid plan caching.   Also partition-handlers often use dynamic SQL, and
a 10% drop in loading rows/second would be a big deal.

Let's put it this way: if the community doesn't backport it, we'll end
up doing so ad-hoc for some of our customers.

-- 
Josh Berkus
PostgreSQL Experts Inc.
http://pgexperts.com


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Next:From: Heikki LinnakangasDate: 2013-01-04 20:23:37
Subject: Re: dynamic SQL - possible performance regression in 9.2
Previous:From: Pavel StehuleDate: 2013-01-04 19:50:55
Subject: Re: dynamic SQL - possible performance regression in 9.2

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