Re: How to force planner to use GiST index?

araza(at)esri(dot)com wrote:
> Hi,
>
> I have a GiST index on st_geometry type (a user defined type). It looks
> like index is not getting hit when I use some geometric operator. Here
> is the example of st_contains operator.
> <snip>
>
> How can I force or direct the planner to use the GiST index? Am I
> missing something?
>
>

For the index to be used you need to use an operator that can make use
of it. eg something like:

select parcel1.id, count(*) from parcel1, polygons where
contains(polygons.the_geom, parcel1.the_geom) and parcel1.geom &&
polygons.the_geom group by parcel1.id;

the && (inside bounding box) is able to use the gist index, whilst the
exact contains is not able to.

Hope that helps,

Joe