function difference(geometry,geometry) is SLOW!

От:

"luke.78@libero.it" <luke.78@libero.it>

Дата:

16 июня 2008 г. в 06:06:54

Hi,
In my pgsql procedure, i use the function

geometryDiff := difference
(geometry1,geometry2);

but this function is very slow!!!
What can I do to 
speed this function?
Exists a special index for it?

Thanks in advance!
Luke