Does Virtuoso have a document store similar to MongoDB where i can JSON Objects and retrieve them programmatically?
Apologies for the very late response.
JSON is stored in Virtuoso by way of transformation to RDF associated with a Named Graph (a Document identified by an IRI).
You can retrieve the stored data using SPARQL Queries i.e., SELECT, CONSTRUCT, or DESCRIBE.
I also tweeted out an example of JSON processed in the manner described above.
Let me know if this helps, or if additional information is required.