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From Jim Ancona <...@anconafamily.com>
Subject Re: Smart Table creation for 2D range query
Date Tue, 09 May 2017 15:11:29 GMT
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.haddad@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 <kurt@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.
> >
>
>
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