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KNN Search Speed Test

SYNOPSIS: Using one million randomly generated points, time finding the ten nearest points to the center of the range by using the KNN distance operator versus using a call to PostGIS ST_Distance(). ## Use ST_Distance() explain analyze SELECT ST_Distance(the_geom, ST_GeomFromText(‘POINT(500 500)’)) FROM tgeom ORDER BY ST_Distance(the_geom, ST_GeomFromText(‘POINT(500 500)’)) asc limit 10; Total runtime: 1568.499 ms […]

KNN GIST Index in Postgresql

With version 9.1 of PostgreSQL and above, the KNN GIST Index is available. There are two new operators defined:  <-> and <#>  With version 2.0 of PostGIS and above, the KNN GIST Index functionality is exposed for PostGIS geometry types. <-> – Returns the distance between two points. For point / point checks it uses […]

RE2

30 Mar 17 Docs and Handoff — WA18 ======================================================== Prediction Run — Pass II * rebuilt tiling – there was a bug in the tiling code that caused gaps, due to a floating point truncation; using %f format for the float, as input to the transform, was insufficient resolution and the tiles were slightly malformed […]