> 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