Re: That EXPLAIN ANALYZE patch still needs work

On Wed, Jun 07, 2006 at 11:34:30AM -0400, Tom Lane wrote:
> timer interrupt routine does this once every few milliseconds:

One issue is that on very fast queries, you'd get absolutely no data
this way. A possible solution would be to start with an extremely short
timer interval, and ramp it up if the query runs longer. The downside is
that you'd need to somehow re-scale iterations every time the timer
interval changed. Of course another option is to start off using the
gettimeofday() method and switch to sampling after X seconds, but it'd
be nice if both code paths weren't needed.

> The bubble-up of sample counts to parent nodes could perhaps be done
> while printing the results instead of on-the-fly as sketched above, but
> the above seems simpler.

It'd be nice if there was an option to not aggregate child runtimes to
their parents at all, since it'd make spotting hot spots much easier.
--
Jim C. Nasby, Sr. Engineering Consultant jnasby(at)pervasive(dot)com
Pervasive Software http://pervasive.com work: 512-231-6117
vcard: http://jim.nasby.net/pervasive.vcf cell: 512-569-9461