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Posted by --CELKO-- on 05/07/06 16:23
Why would you have a NULL identifier? I guess that two things can have
the same location, otherwise (x,y,z) would be a key. And should your
query look like this, since you want to go in both directions.on an
axis? The OUTER JOIN makes no sense.
SELECT A.node_id, B.node_id
FROM Locations AS A, Locations AS b
WHERE A.node_id < B.node_id
AND ABS(A.x-B.x) <= 2
AND ABS(A.y-B.y) <= 2
AND ABS(A.z-B.z) <= 2
I did something like in 2-D for neighborhoods based on quadrants. If a
node was in one quadrant, I assumed that the nine adjacent quads
centered on his quad would have the nearest neighbor, so i only did a
distanve formula on popint in those quads. It meant carrying an extra
pair of quad co-ordinates, but it saved searching all the nodes -- 9
quads versus ~15,000 quads.
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