[JENA-754] Avoid using a wrapper dataset for SPARQL Update WITH

• Type: Bug
• Status: Closed
• Priority: Minor
• Resolution: Fixed
• Affects Version/s: Jena 2.11.2
• Fix Version/s: Jena 2.12.1
• Component/s: ARQ
• Assignee: Andy Seaborne
• Reporter: Andy Seaborne
• Created: 30/Jul/14 21:15
• Updated: 31/Jul/14 19:44
• Resolved: 31/Jul/14 19:44

Description

When processing a SPARQL Update operation that uses WITH, the processing engine crates a wrapper dataset DatasetGraphAltDefaultGraph that catches access to the default graph and directs it to the alternative graph.

This can block optimization of the graph pattern because DatasetGraphAltDefaultGraph masks the true storage layer and will use the default query pattern executor (OpExecutor and StageGeneratorGeneric).

This is not too serious now that the generic process does some optimization but it can be improved by modifying the WHERE clause to wrap it in a GRAPH <URI>

{...}

using ElementGraph and not using a wrapper dataset. The pattern matching proceeds to the underlying storage engine as normal.