[postgis-devel] Why doesn't knn work on table1.geom <#>table2.geom

Nicklas Avén nicklas.aven at jordogskog.no
Sun Oct 2 03:58:36 PDT 2011

I have been playing some with the new knn-implementation.

If I write the query as Paul illustrates like

SELECT id, table1.geom<->ST_SetSrid('POINT(1,2)'::geometry, 3021) as
FROM table1
ORDER BY distance

Then the index kicks in and works as expected.

But if I take the second geometry, the point directlu from a table it
doesn't work like:

SELECT id, table1.geom<->table2.geom as distance
FROM table1, (SELECT geom FROM table1 where gid=1;) AS table2
ORDER BY distance


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