Is my understanding of Virtuosos architecture correct?
I have made a illustration of the dataflow in Virtuoso.
It shows how a SPARQL query is recieved by some kind of handler / cache, it redirected to RDF views where the query is transformed to SQL. From there the RDBMS recieve the query and transforms the data to RDF by use of quad mappings and then returned to the user.
Is this correct, how do Virtuoso really do this? What is the handler called, am i missing any components / important details?
this is not a real answer, but I don't have enough reputation to comment:
You might want to take a look at the SQL-Function: sparql_to_sql_text(sparql query) (virtuoso function guide)
and SPARQL_EVAL(..) here: SPARQL_EVAL
as well as the implementation of SPARQL_EVAL here : SPARQL_EVAL imp
This should give you some hints of what is happening in virtuoso when executing a sparql query.
Greetings.