Incorrect row count estimation for 3D index

[olegmyrk]

I have a problem that Postgis 3D spatial indexes (built using gist_geometry_ops_nd) do not estimate index lookup row count properly,unlike 2D spatial indexes which are working OK.

The 2D query is something like:

position && ST_GeomFromText('LINESTRING(-180 -90, 180 90)', 4326)

And 3D query is something like:

position &&& ST_GeomFromText('LINESTRING(-180 -90 0, 180 90 10000000000)', 4326)

In case of 2D query, query planner gives realistic row count estimates. In case of 3D, the result set is always estimated to be 0.1% of rows.

As a result of incorrect 3D query row estimation, query planner always thinks that spatial query is highly selective and ignores other indexes it might have used otherwise.

Is this a bug or am I missing something? I am using Postgis 2.0.1 on Postgresql 9.1

[olegmyrk]

Example sql transcript

[pramsey]

It's a bug or a missing feature depending on your mood and the time of day. Described in #945.