How to filter big datasets in Geoserver WMS?

Is there a good way to filter datasets with approx 50,000 features in Geoserver? I'd have to select between 100 and 200 features based on ids. These ids are different from the FeatureIds. Couldn't find an "IN" operator similar to SQL in OGC Filter Encoding Standard. Combining multiple PropertyIsEqualTo operators performs really poorly.

Answer

Ah. In that case, you could use GeoServer's WMS CQL filter support, i.e.:

http:///wms?service=WMS&version=1.1.1&request=GetMap&....&cql_filter=IN ('id_1','id_2','id_3')

More information is available at http://geoserver.org/display/GEOSDOC/WMS+vendor+parameters