Hi,
Paul Matthews <plm@netspace.net.au> writes:
> Witting a box@>point function easy. Having a spot of trouble trying to
> figure out where and how to graft this into the GiST stuff. Could
> someone please point me in the general direction?
You want index support for it, I suppose?
Without index support (but needed anyway), you implement your code in a
C module then make it visible from SQL. I'm not sure you're asking help
for the C part so don't expand, please ask more if needed:
CREATE OR REPLACE FUNCTION box_contains_point(box, point)
RETURNS bool
AS 'MODULE_PATHNAME'
LANGUAGE 'C' IMMUTABLE STRICT;
CREATE OPERATOR @> (LEFTARG = box,RIGHTARG = point,PROCEDURE = box_contains_point,COMMUTATOR = '<@',RESTRICT =
contsel,JOIN = contjoinsel
);
COMMENT ON OPERATOR @>(box, point) IS 'box contains point?';
Now for adding support for index lookups, you have to see documentation
about OPERATOR CLASS and OPERATOR FAMILY. I guess you need to make a
family out of point and box if none already exists, add the @> operator
there and point to your function.
I'm unclear if you need to add it to an OPERATOR CLASS too and which, so
I won't risk into writing the commands. Cross datatype indexing support,
as far as I've understood, is tied together with operator families.
Hope this helps, regards,
--
dim
