Hi all, since this has been asked every now and then [1] and since I think it's a pretty useful and common feature for search engine nowadays I'd like to discuss introduction of facets [2] for the Oak query engine.
Pros: having facets in search results usually helps filtering (drill down) the results before browsing all of them, so the main usage would be for client code. Impact: probably change / addition in both the JCR and Oak APIs to support returning other than "just nodes" (a NodeIterator and a Cursor respectively). Right now a couple of ideas on how we could do that come to my mind, both based on the approach of having an Oak index for them: 1. a (multivalued) property index for facets, meaning we would store the facets in the repository, so that we would run a query against it to have the facets of an originating query. 2. a dedicated QueryIndex implementation, eventually leveraging Lucene faceting capabilities, which could "use" the Lucene index we already have, together with a "sidecar" index [3]. What do you think? Regards, Tommaso [1] : http://markmail.org/search/?q=oak%20faceting#query:oak%20faceting%20list%3Aorg.apache.jackrabbit.oak-dev+page:1+state:facets [2] : http://en.wikipedia.org/wiki/Faceted_search [3] : http://lucene.apache.org/core/4_0_0/facet/org/apache/lucene/facet/doc-files/userguide.html
