[postgis-users] GIST index speed

Mark Cave-Ayland mark.cave-ayland at siriusit.co.uk
Mon Jun 9 06:34:18 PDT 2008

Paul Ramsey wrote:
> I bet when you have the function it's caching the result, and when you
> don't, it's re-fetching it. And because the bare result is a toasted
> tuple, the re-fetch is a lot more expensive.
> P.

Hi Paul,

If only it were that simple ;)  I'd already tried removing the IMMUTABLE 
definition from SQL definition of mcatest() and it didn't make any 
difference to me - probably because adding a POSTGIS_DEBUG macro shows 
that it only gets called once in total rather than once per iteration of 
the nested loop scan.



Mark Cave-Ayland
Sirius Corporation - The Open Source Experts
T: +44 870 608 0063

More information about the postgis-users mailing list