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Re: dynamic SQL - possible performance regression in 9.2

From: Heikki Linnakangas <hlinnakangas(at)vmware(dot)com>
To: Josh Berkus <josh(at)agliodbs(dot)com>
Cc: pgsql-hackers(at)postgresql(dot)org
Subject: Re: dynamic SQL - possible performance regression in 9.2
Date: 2013-01-04 20:23:37
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Lists: pgsql-hackers
On 04.01.2013 22:05, Josh Berkus wrote:
>> 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.

+1 for backpatching.

- Heikki

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