[JENA-294] TransformFilterEquality does not handle starting OPTIONAL well

• Type: Improvement
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: Jena 2.7.4
• Fix Version/s: Jena 2.10.0
• Component/s: ARQ, Optimizer
• Assignee: Unassigned
• Reporter: Simon Helsen
• Created: 13/Aug/12 19:00
• Updated: 17/Apr/13 11:38
• Resolved: 17/Apr/13 11:32

Description

There was one other case where our tests were stuck on a very slow query execution because transformFilterEquality failed to optimize. The problem is that the optimizer gives up whenever the WHERE clause starts with an OPTIONAL clause. The reason is that the generated algebraic formula starts with a TableUnit and this is not handled correctly.

I have attached a patch which fixes the problem

Issue Links

• is related to: JENA-432 Filter optimization messes up when a nested select is present in the same block
• is related to: JENA-383 The query optimizer generates a suboptimal query plan in case of nested optionals followed by a filter