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 a "IN" operator similar to SQL in OGC Filter Encoding Standard. Combining multiple PropertyIsEqualTo operators performs really poorly.
Ah. In that case, you could use GeoServer's WMS CQL filter support, i.e.:
More information is available at http://geoserver.org/display/GEOSDOC/WMS+vendor+parameters
You could pass a list of feature id's in the following manner:
The POST option is obviously more verbose, but less than looping PropertyIsEqualTo constructs.