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

Tip:

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.