[postgis-users] Is my query planner failing me, or vice versa?

[strk at refractions.net]

Jessica, 
the query plan sounds good to me, if it is performance
differences that hit your attention I guess they are due
to GeomUnion operating on differently complex geometries.

If you can handle to isolate the input geometries of
the slow operation that would help further analisys.

Also, telling us GEOS version (postgis_full_version())
would be helpful.

--strk;