[#SES-589] LuceneSail fails to evaluate GraphQuery due to bug in Native and Memory Store

Issue Details [XML]

Key:	SES-589
Type:	Bug
Status:	Open
Priority:	Major
Assignee:	Unassigned
Reporter:	Enrico Minack
Votes:	0
Watchers:	0

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Sesame

LuceneSail fails to evaluate GraphQuery due to bug in Native and Memory Store

Created: 20/Aug/08 02:50 PM Updated: 20/Aug/08 03:11 PM

Component/s:

Memory Sail, Native Sail

Affects Version/s:

2.1, 2.1.1, 2.1.2, 2.1.3

Fix Version/s:

None

Description

The LuceneSail test for GraphQuery's (org.openrdf.sail.lucene.LuceneSailTest.testGraphQuery()) succeeds with Sesame 2.0, but fails with the Sesame 2.1 branch due to the following problem:

The LuceneSail evaluates this query using the underlying sail:

Distinct
   MultiProjection
      ProjectionElemList
         ProjectionElem "r" AS "subject"
         ProjectionElem "-const-6" AS "predicate"
         ProjectionElem "r2" AS "object"
      ProjectionElemList
         ProjectionElem "r" AS "subject"
         ProjectionElem "-const-7" AS "predicate"
         ProjectionElem "s" AS "object"
      Extension
         ExtensionElem (-const-6)
            ValueConstant (value=urn:predicate3)
         ExtensionElem (-const-7)
            ValueConstant (value=http://www.openrdf.org/contrib/lucenesail#score)
         Distinct
            Projection
               ProjectionElemList
                  ProjectionElem "r"
                  ProjectionElem "r2"
                  ProjectionElem "s"
               Join
                  Join
                     Join
                        SingletonSet
                        SingletonSet
                     SingletonSet
                  StatementPattern
                     Var (name=r)
                     Var (name=-const-5, value=urn:predicate3, anonymous)
                     Var (name=r2)

The Statement pattern provides bindings for r2, whereas the values for r and s comes via the given binding set. In the end, the MultiProjection should generate statements out of the r2 and the given r and s. The bindings are
r=urn:subject3
s="0.8784157"^^http://www.w3.org/2001/XMLSchema#float

during
optimizerList.optimize(tupleExpr, dataset, bindings);
in the underlying sail (Memory or Native), the variable
Var (name=r)
is optimized to
Var (name=r, value=urn:subject3)

but since s is not in the tree, it is not injected into the tree. Then,
iter = strategy.evaluate(tupleExpr, EmptyBindingSet.getInstance());
is called, so that the given bindings are not further used for evaluation. This
is the reason why the s in
      ProjectionElemList
         ProjectionElem "r" AS "subject"
         ProjectionElem "-const-7" AS "predicate"
         ProjectionElem "s" AS "object"

gets not filled with the value given via the bindings.

changing
iter = strategy.evaluate(tupleExpr, EmptyBindingSet.getInstance());
to
iter = strategy.evaluate(tupleExpr, bindings);
lets the test pass and all sesame tests still succeed.

With this fix, LuceneSail can be set to use Sesame 2.1.

All

Comments

Change History

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[ Permlink ]

Comment by Enrico Minack [20/Aug/08 03:02 PM]

I added a test to the LuceneSail project:
src/test/java/org/openrdf/sail/lucene/GraphQueryTest.java
This is independent of the LuceneSail, suceeds with Sesame 2.0 but fails with Sesame2.1. Simply set the sesame version to 2.1 in the LuceneSail pom.file and run the tests.

[ Permlink ]

Comment by James Leigh [20/Aug/08 03:03 PM]

This was introduced as part of a fix to ~~SES-541~~: Externally set bindings are erroneously included in query result; extended RDFStoreTest to verify ~~SES-541~~.

http://www.openrdf.org/issues/browse/SES-541
http://repo.aduna-software.org/viewvc?view=rev&revision=6474

[ Permlink ]

Comment by Enrico Minack [20/Aug/08 03:11 PM]

So this behaviour is desired?