[hibernate-issues] [Hibernate-JIRA] Created: (HHH-5034) Make CriteriaImpl.uniqueResult() more robust

[Tomas Pollak (JIRA)]

Make CriteriaImpl.uniqueResult() more robust
--------------------------------------------

                 Key: HHH-5034
                 URL: http://opensource.atlassian.com/projects/hibernate/browse/HHH-5034
             Project: Hibernate Core
          Issue Type: Improvement
          Components: core
    Affects Versions: 3.3.1
            Reporter: Tomas Pollak


We are using Sybase for generating a query that has a COUNT(*) and ORDER BY. Granted, the 'order by' doesn't have any semantic effect, but it's a dynamically generated query, and we need to know the total count as well as the actual result.

The problem is that Sybase returns many rows for such a query, and the uniqueResult() fails with a NonUniqueResultException. Although every returned row contains an Integer with the same value, they are different instances.

We could modify the AbstractQueryImpl.uniqueElement(List list) as follows:


	static Object uniqueElement(List list) {
		int size = list.size();
		if (size == 0) return null;

		Object first = list.get(0);
		for (int i = 1; i < size; i++) {
			if (!safeEquals(first, list.get(i))) {
				throw new NonUniqueResultException(list.size());
			}
		}
		return first;
	}
	
	static boolean safeEquals(Object first, Object second) {
		if (first instanceof Integer && second instanceof Integer) {
			return ((Integer)first).compareTo((Integer)second) == 0;
		}
		return first == second;
	}

That would solve our issue.
Thanks.

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