Re: [INTERFACES] postgres for spatial data

>         I'm looking for a graphical interface that can display the
> geometric types like polygon,...

Don't know about pre-built utilities for graphical display of geometric
objects. Let us know what you discover.

>         I'm also looking for SQL extension in order to make
> spatial queries (for example, a function that tells if a point
> belongs to the interior of a polygon)

There are already some operators available; for example, the "@"
operator is for "on or inside":

postgres=> select '(0,0)'::point
postgres->  @ '((0,1),(1,0),(0,-1),(-1,0))'::polygon;
?column?
--------
t
(1 row)

Look in the hardcopy or html doc set which is included in v6.3.x. You
need to do a "make install" from the doc directory to get them unpacked.
Good luck...

                         - Tom