Methods and apparatus for querying a relational data store using schema-less queries

A method for translating a schema-less input query in a first language to an output query in a second language comprising:

• examining the schema-less input query in the first language for one or more tokens that represent data to be used in generating the output query;
• dispatching context-specific grammar events containing the data, represented by the tokens in the examined first query, to be used in generating the second query,
• populating portions of the output query according to the events and data;
• and
• extracting data, represented by the tokens and contained within the context-specific grammar events, from the context-specific grammar events to generate the output query in the second language, comprising those populated portions, as a translation of the input query into second language, wherein the output query represents a schema of a relational database storing resource description framework (“RDF”) triples and wherein the output query comprises
• a single SQL SELECT statement with a WHERE clause containing three or more logical conditions limiting triples to be considered for retrieval from the RDF triples data store, where each logical condition specifies one or more RDF triples according to a boolean condition;
• wherein each of the events represents any of a declaration and a constraint specified in the first query, and
• wherein the constraint specifies RDF triples to be identified.

A digital system for searching a resource description framework (“RDF”) triples data store having a storage schema, comprising:

• a parser component to examine a schema-less, first query specifying one or more RDF triples to be identified, the parser component examines the first query for one or more tokens that represent data to be used in generating a second query and that dispatches context-specific grammar events containing the data, represented by the tokens in the examined first query, to be used in generating the second query, wherein each of the events represents any of a declaration and a constraint specified in the first query and wherein the constraint specifies RDF triples to be identified;
• an event-processing component coupled to the parser component, the event-processing component to extract statement data, represented by the tokens and contained within the context-specific grammar events, from one or more of the context-specific grammar events;
• a statement component coupled to the event-processing component, the statement component to generate the second query so as to identify the same RDF triples identified in the schema-less, first query and so as to reflect the storage schema of the RDF triples data store, where the second query comprises:
• a single SQL SELECT statement with a WHERE clause containing three or more logical conditions limiting triples to be considered for retrieval from the RDF triples data store, where each logical condition specifies one or more RDF triples according to a boolean condition.