Manually specifying how to build an index?

I'm looking into Thinking Sphinx for it's potential to solve an indexing problem. It looks like it has a very specific API for telling it what fields to index on a model. I don't like having this layer of abstraction in my way without being able to sidestep it. The thing is I don't trust Sphinx to be able to interpret my model properly as this model could have any conceivable property. Basically, I want to encode JSON in a RDBMS. In a way, I'm looking to make an RDBMS behave like MongoDB (RDBMSes have features I don't want to do without). If TS or some other开发者_高级运维 index could be made to understand my models this could work. Is it possible to manually provide key/value pairs to TS?

"person.name.first" => "John", "person.name.last" => "Doe", "person.age" => 32, 
"person.address" => "123 Main St.", "person.kids" => ["Ed", "Harry"]

Is there another indexing tool that could be used from Ruby to index JSON?

(By the way, I have explored a wide variety of NoSQL databases. I am trying to address a very specific set of requirements.)

As Matchu has pointed out in the comments, Sphinx usually interacts directly with the database. This is why Thinking Sphinx is built like it is.

However, Sphinx (but not Thinking Sphinx) can also accept XML data formats - so if you want to go down that path, feel free. You're going to have to understand the underlying Sphinx structure much more deeply than you would if using a normal relational database/ActiveRecord and Thinking Sphinx approach. Riddle may be useful for building a solution, but you'll still need to understand Sphinx itself first.

Basically, when you're specifying what you want to index--that is, when you want to build your own index--you're using the Map part of Map/Reduce. CouchDB supports exactly this. The only problem I ran into with Couch is that I want to query other document objects as the basis of my Map/Reduce since those documents would contain metadata about how I want to build my indexes. This goes against the grain of Map/Reduce however as you have to map a document in isolation with no external data. If you need external data it would instead be denormalized into your documents.