relational design in solr?

[Joachim Martin]

I am trying to integrate solr search results with results from a rdbms 
query.  It's working ok, but fairly complicated  due to large size of 
the results from the database, and many different sort requirements.

I know that solr/lucene was not designed to intelligently handle 
multiple document types in the same collection, i.e. provide join 
features, but I'm wondering if anyone on this list has any thoughts on 
how to do it in lucene, and how it might be integrated into a custom 
solr deployment.  I can't see going back to vanilla lucene after solr!

My basic idea is to add an objType field that would be used to define a 
"table".  There would be one main objType, any related objTypes would 
have a field pointing back to the main objs via id, like a foreign key.

I'd run multiple parallel searches and merge the results based on 
foreign keys, either using a Filter or just using custom code.  I'm 
anticipating that iterating through the results to retrieve the foreign 
key values will be too slow.

Our data is highly textual, temporal and spatial, which pretty much 
correspond to the 3 tables I would have.  I can de-normalize a lot of 
the data, but the combination of times, locations and textual 
representations would be way too large to fully flatten.

I'm about to start experimenting with different strategies, and I would 
appreciate any insight anyone can provide.  Would the faceting code help 
here somehow?

Thanks --Joachim