[OPENJPA-2964] Honour the query range on set operations - #172
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executeSetOperatorQuery() received the StoreQuery.Range but never used it, so setFirstResult()/setMaxResults() were silently ignored on a UNION, INTERSECT or EXCEPT query. The range is applied in memory over the compound result, through RangeResultObjectProvider, which is the same fallback the ordinary path uses when the dictionary cannot express a range in SQL. It cannot be pushed into the statement: DBDictionary.toSelect() renders the first operand in full, including any limit derived from the select's start and end index, and only then appends the set operator buffer, so a range on the main select would bind to the first operand instead of to the compound result. A javadoc on the method records that, since the optimisation is tempting and silently wrong. testSetOperatorRange covers UNION ALL, UNION, INTERSECT and EXCEPT, and both provider branches. It asserts cardinality only: JPQL attaches an ORDER BY to an individual select, so the row order of a compound set operation is undefined.
solomax
approved these changes
Sep 3, 2026
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executeSetOperatorQuery()received theStoreQuery.Rangebut never used it, sosetFirstResult()/setMaxResults()were silently ignored on a UNION, INTERSECT or EXCEPT query.The range is applied in memory through
RangeResultObjectProvider, the same fallback the ordinary path uses when the dictionary cannot express a range in SQL. It cannot be pushed into the statement:DBDictionary.toSelect()renders the first operand in full, including any limit derived from the select's start and end index, and only then appends the set-operator buffer — so a range on the main select would bind to the first operand instead of to the compound result, returning wrong rows rather than none. A javadoc on the method records that, since the optimisation is tempting and silently wrong.testSetOperatorRangecovers UNION ALL, UNION, INTERSECT and EXCEPT and both provider branches, asserting cardinality only: JPQL attaches ORDER BY to an individual select, so the row order of a compound set operation is undefined.