[postgis-devel] 3d kNN GiST?

[hubert depesz lubaczewski]

Hi,
For my project I need fast searching for nearest neighbors in 3d space.

We use postgis geometry with POINT(x y z), but apparently <-> doesn't show
3d distance, but rather 2d. Which is kinda bummer (why isn't it even listed
in docs?).

Anyway - on IRC I was said to:

CREATE OR REPLACE FUNCTION geometry_distance_centroid(geom1 geometry, geom2
geometry) RETURNS float8 AS 'SELECT ST_3DDistance($1,$2)' LANGUAGE 'sql'
IMMUTABLE STRICT;

And then <-> will work with 3d, but will that also work *correctly* with
gist indexes?

Regards,

depesz
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