Solr has a feature called Field Collapsing which allows grouping of search results. Is there a similar feature available with Hibernate Search?

For example, I have a Product which has an embedded Category. I want to be able to search on product.name and group my results by product.category.id with a limit on the number of results in each category - I may have 50 results overall when searching for "dog" with results spread over 3 categories, but for each category, I only want to return the first 5 results.

Hi,

I assume you are referring to faceted search when talking about grouping. Currently Hibernate Search does not have anything like this built-in, even though we have been talking about it. It should not be hard so to implement something on your own though. Maybe this Lucene Jira issue LUCENE-1421 is helpful. Using a custom Collector seems to be promising.

--Hardy

Its not faceting that I am referring to. Field Collapsing is described on the solr wiki.

Hi Dave,
I've seen the implementation of Field Collapsing some while ago, so although it might have changed, it's a post-processor on the results retrived by Lucene; you can easily implement the same iterating on the results when using Hibernate Search as the index is not a remote service, just make sure you use projections to avoid fetching the whole database in memory. Solr needs this as a remote component to keep the resulting XML/Json/.. as short as possible, but in our case such a feature is hardly needed.