Re: Re: pg_stat_statements normalisation without invasive changes to the parser (was: Next steps on pg_stat_statements normalisation)

On 8 April 2012 20:51, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> Applied with some cosmetic adjustments.

Thanks.

Having taken another look at the code, I wonder if we wouldn't have
been better off just fastpathing out of pgss_store in the first call
(in a pair of calls made by a backend as part an execution of some
non-prepared query) iff there is already an entry in the hashtable -
after all, we're now going to the trouble of acquiring the spinlock
just to increment the usage for the entry by 0 (likewise, every other
field), which is obviously superfluous. I apologise for not having
spotted this before submitting my last patch.

I have attached a patch with the modifications described.

This is more than a micro-optimisation, since it will cut the number
of spinlock acquisitions approximately in half for non-prepared
queries.

--
Peter Geoghegan       http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Training and Services