| By default, WFS requests wrap the underlying feature collection with a FeatureSizeFeatureCollection. FeatureSizeFeatureCollection overrides size(), and iterates over all the underlying features if a negative value is returned from the underlying feature collection. I believe that returning -1 is a valid response to size(), and that seemed to be confirmed by Jody in the original PR that added the FeatureSizeFeatureCollection (https://github.com/geoserver/geoserver/pull/1355#issuecomment-263688535). In GeoMesa, by default return we -1, as counts are expensive for us, but we allow overriding that behavior with a system property or a query hint. We have an optimized method to determine counts when needed, which is much faster than iterating over the entire feature collection, but that is being bypassed here. As a proposed solution, I would suggest setting the default value for DEFAULT_CACHE_SIZE to 0 in FeatureSizeFeatureCollection. That way, it would be disabled by default, but could easily be enabled by setting the system property. It seems long-term it would be nice to have a standardized way to request a quick count vs an accurate count. |
