When are spatial indexes used?
Spatial indexes are used with queries that call functions to compare geometries. The Oracle and PostgreSQL ST_Geometry functions that use spatial indexes are the ones that test spatial relationships.
- ST_Contains (PostgreSQL only)
- ST_Crosses
- ST_Disjoint (PostgreSQL only)
- ST_Equals
- ST_Intersects
- ST_Overlaps
- ST_Relate (Oracle only)
- ST_Touches
- ST_Within
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For information on DB2 ST_Geometry functions that can use a spatial index, see the DB2 documentation.
See the IBM Informix Spatial DataBlade Module User's Guide for information on functions that utilize Informix's R-tree spatial index.
Additionally, the spatial column must appear immediately after the spatial relationship function in the query for the spatial index to be used.
11/18/2013