Each pair of columns (min/max) represents one dimension. So for latitude/longitude coordinates you would have 5 columns: 1 id column and 2 columns each for latitude and longitude. 5 "columns" equates to 2 dimensions of data. 7 "columns" equates to 3 dimensions of data. Etc.
HTH. -Shane On 6/9/08, Christophe Leske <[EMAIL PROTECTED]> wrote: > > > > You can improve performance (space/speed) a little by changing the > > RTREE_MAX_DIMENSIONS at the top of rtree.c to match you data set. It > > defaults to 5 dimensions, but you could reduce to this to 2, or 3 with > city > > size. > > > > #define RTREE_MAX_DIMENSIONS 5 > > > Hi Shane, > > thanks for the answer. > > AFAIK, this wouldn´t work though, as 3 dimensions would mean that you could > only query if a given point is in a line? > > If i do a 3 dimensional rtree, then > > 1 field = ID > 2 field = longitude_min > 3 field = longitude_max (and NOT latitude) > > The third parameter also always needs to be smaller than the second one > passed (or generally spoken, the second one has always to be bigger than the > first one), otherwise a rtree request wouldn´t work... > > Say we would do such a 3 dimensional rtree (id, longitude, latitude) - how > could I query for cities in a given rectangle? > > Select * from rtree where longitude>longitude_minimal and longitude<maximal > and latitude>latitude_minimal and latitude<latitude_maximal? > > Would that actually work? > > > > Christophe Leske > > www.multimedial.de - [EMAIL PROTECTED] > http://www.linkedin.com/in/multimedial > Lessingstr. 5 - 40227 Duesseldorf - Germany > 0211 261 32 12 - 0177 249 70 31 > > > _______________________________________________ > sqlite-users mailing list > sqlite-users@sqlite.org > http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users > _______________________________________________ sqlite-users mailing list sqlite-users@sqlite.org http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users
