Were you able to try this Christophe? I expect it to only be a very slight performance improvement, but I'm still curious as to how much.
On 6/9/08, Shane Harrelson <[EMAIL PROTECTED]> wrote: > > 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
