> The results are ok, but the query is too slow. I tried to applay a GIST and
> gtree index but performance did not improve.
> By explaining the query I see that the where condition gets the query slow.
> Is there a more simple way to check if two poligons have a not null
> intersection (they overlap)?
>
> Is there a kind of index I can use ?
If you stored the polygon geometries in the same table, you could use
a functional index (give the CREATE INDEX statement a function to
evaluate rather than a column). Check the CREATE INDEX page for
caveats. Beware that the index would grow with the square of the
number of rows if you did it like this.
Peter