[postgis-devel] Btree operators

Komяpa me at komzpa.net
Thu Apr 7 04:22:42 PDT 2016


hey there,

https://trac.osgeo.org/postgis/ticket/3521 floated nearby me and broke my
heart.

Can we have SELECT DISTINCT work for sure as a complete compare, not just
bbox one?

It also touches the topic of sorting the boxes - it seems now they're
sorted by X, then by Y - which is usually a poor way to preserve spatial
locality. Can we sort by z-order curve instead? just bit-mix all the
coordinates: https://en.wikipedia.org/wiki/Z-order_curve - that will make
painful voodoo stuff like ORDER BY
ST_GeoHash(ST_Transfrom(ST_Centroid(geom),4326)) much cleaner and replace
it with just CLUSTER (see
https://github.com/openstreetmap/osm2pgsql/issues/208 ).
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