There are clever ways to encode coordinates into a single scalar value where points that are close on a surface are also close in value, making queries efficient. Examples are Geohash <https://en.wikipedia.org/wiki/Geohash> and Google's S2 <https://docs.google.com/presentation/d/1Hl4KapfAENAOf4gv-pSngKwvS_jwNVHRPZTTDzXXn6Q/view#slide=id.i0>. As Jon mentions, this puts more work on the client, but might give you a lot of querying flexibility when using Cassandra.
Jim On Mon, May 8, 2017 at 11:13 PM, Jon Haddad <jonathan.had...@gmail.com> wrote: > It gets a little tricky when you try to add in the coordinates to the > clustering key if you want to do operations that are more complex. For > instance, finding all the elements within a radius of point (x,y) isn’t > particularly fun with Cassandra. I recommend moving that logic into the > application. > > > On May 8, 2017, at 10:06 PM, kurt greaves <k...@instaclustr.com> wrote: > > > > Note that will not give you the desired range queries of 0 >= x <= 1 and > 0 >= y <= 1. > > > > > > Something akin to Jon's solution could give you those range queries if > you made the x and y components part of the clustering key. > > > > For example, a space of (1,1) could contain all x,y coordinates where x > and y are > 0 and <= 1. You would then have a table like: > > > > CREATE TABLE geospatial ( > > space text, > > x double, > > y double, > > item text, > > m1, > > m2, > > m3, > > primary key ((space), x, y, m1, m2, m3, m4, m5) > > ); > > > > A query of select * where space = '1,1' and x <1 and x >0.5 and y< 0.2 > and y>0.1; should yield all x and y pairs and their distinct metadata. Or > something like that anyway. > > > > > --------------------------------------------------------------------- > To unsubscribe, e-mail: user-unsubscr...@cassandra.apache.org > For additional commands, e-mail: user-h...@cassandra.apache.org > >
