Each item in the store has its own URI based on its unique identifier:
The SPARQL service associated with a platform store uses a fixed default (background) graph. The contents of this graph is the contents of the Metabox.
The service does not support specifying the dataset in either the protocol (using default-graph-uri and named-graph-uri parameters) or within the SPARQL query itself (using FROM and FROM NAMED).
The Store Multisparql Service does provide some additional options for querying multiple graphs.
Note: for backwards compatibility, where the text/turtle media type is listed, the deprecated application/x-turtle media type is also supported, though it is given a lower weighting during Content Negotiation
The following table summarizes the content-negotiation logic for obtaining the sparql results as JSONP using the output (or Accept header) and the callback parameter (see here for all the logic). The output parameter, if set, will override the Accept header.
The SPARQL service endpoint enforces a maximum execution time for all SPARQL queries. This is to ensure that long-running queries do not degrade the service for other users. Queries that exceed the maximum allowable time will be terminated and a 500 Internal Server error response returned.
The SPARQL service endpoint includes support for some extensions to the SPARQL query language. The full list of SPARQL Extensions are documented separately.
The official SPARQL protocol specification has additional information on specifying queries, response formats and error conditions.