Herman has added the aggregates support in Bobo. We need to examine those changes and to incorporate them into the Bobo
"The patch I have included in this mail contains the implementation. It implements the following aggregates: sum, average, min & max. The com.browseengine.bobo.client.AggregateTest gives you an idea how to use the aggregation functionality. All aggregates haven been implemented using a custom FacetHandler: com.browseengine.bobo.facets.impl.GroupbyAggregateFacetHandler."