I listened with great interest to Grant's presentation of the NoSQL comparisons/alternatives to Solr/Lucene. It sounds like the jury is still out on much of this. Here's a use case that might favor using a NoSQL alternative for storing 'stored fields' outside of Lucene.
When Solr does a distributed search across shards, it does this in 2 phases (correct me if I'm wrong): 1. 1st query to get the docIds and facet counts 2. 2nd query to retrieve the stored fields of the top hits The problem here is that the index could change between (1) and (2), so it's not an atomic transaction. If the stored fields were kept outside of Lucene, only the first query would be necessary. However, this would mean that the external NoSQL data store would have to be synchronized with the Lucene index, which might present its own problems. (I'm just throwing this out for discussion) Peter
