we use Hibernate Search in our application. We use faceting. Recently we have found a big limitation. Faceting over fields that can have multiple values doesn't work properly with Hibernate Search - if a document has multiple values for faceted field (ex. multiple categories), only one of the values is taken into account. 

I can currently think of a couple two solutions:

* use bobo-browse (http://code.google.com/p/bobo-browse/)
* solr (http://lucene.apache.org/solr/)

In both solutions we continue to maintain the index using Hiberante Search and making queries as we did before (using Hiberante Search), and run additional bobo-browse or solr query for faceting, where required (bobo-browse or solr would use index in kind of "read-only" manner). The problem is that we update index quite often, and would like to get really fresh data in faceting queries. Bobo-browse doesn't automatically integrate with Hiberante Search, and to keep search up to date, I might get into some problems (ex. <https://groups.google.com/forum/?fromgroups=#!topic/bobo-browse/sn_Efc-YClU>). The documentation looks a bit untidy and not yet completed. Solr on the other hand seems like a really big thing to add, just to get faceting work properly. And I'm still afraid I might run into some problems with updating/refreshing index.

Do you have any experience in that matter? Any suggestions?