[postgis-users] Indexes on table with 200,000 rows

[Paul Austin]

I have a table with a geometry column in BC Albers (3005) for which I have
created a GIST index. I'm using postgresql 8.3.7 with Postgis 1.3.5-1.

CREATE INDEX my_table_geom_gist
  ON my_table
  USING gist
  (geom);

I ran the VACUUM ANALYZE on the table.

When I run the following it shows a sequential scan rather than an index
scan.
explain SELECT  geom FROM my_table WHERE geom && 'BOX3D(250982 1754957,
1369941 482671)'::box3d

Ultimately I want to be able to query using the ST_Intersects function but
if the index is not being used with the && operator then it's unlikely to
using the index with ST_Intersects.

In some forum posts there was a gist_geometry_ops option when creating
indexes but that doesn't seem to work with the version I have.

What are the real secrets to get postgis to use spatial indexes? Or do I
just not have enough data in my tables?

Paul
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