Hi I need to set a query which performs a intersection check between two set of polygons which are stored into two tables. I wrote the where instruction so: ... where area(intersection(t1.the_geom,t2.the_geom))>0 ... 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 ? THanks Giu -- Email.it, the professional e-mail, gratis per te: http://www.email.it/f Sponsor: Hai bisogno di contanti per realizzare i tuoi desideri? Prometeo ti propone prestiti da 1.500 a 31.000 Euro! Clicca qui per un preventivo immediato. Clicca qui: http://adv.email.it/cgi-bin/foclick.cgi?mid=6916&d=20070827 ---------------------------(end of broadcast)--------------------------- TIP 1: if posting/reading through Usenet, please send an appropriate subscribe-nomail command to majordomo@xxxxxxxxxxxxxx so that your message can get through to the mailing list cleanly