Collapse nested OR expressions
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Key: JCR-2759
URL: https://issues.apache.org/jira/browse/JCR-2759
Project: Jackrabbit Content Repository
Issue Type: Improvement
Components: jackrabbit-core
Reporter: Marcel Reutegger
Priority: Minor
Executing a query with multiple OR expressions in a predicate leads to score
values that depend on the order of the operands.
For example, the following query:
//*[jcr:contains(@prop1, 'foo') or jcr:contains(@prop2, 'foo') or
jcr:contains(@prop3, 'foo')] order by @jcr:score descending
will return a slightly different result compared to:
//*[jcr:contains(@prop3, 'foo') or jcr:contains(@prop1, 'foo') or
jcr:contains(@prop2, 'foo')] order by @jcr:score descending
Internally jackrabbit parses the predicate of the first query into a tree:
orExpr(orExpr(contains(prop1, 'foo'), contains(prop2, 'foo')), contains(prop3,
'foo'))
Lucene will calculate the score for the inner OR expression first and then for
the outer, which is not equivalent with a nested expression that has property
names in a different sequence.
The query should be translated internally into a single OR expression with
three operands. That way, the score value is always the same, irrespective of
the order of the operands.
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