getCountQuery doesn't respect distinct flag

It seems our getCountQuery implementation doesn’t respect the distinct flag i.e. it should construct a count(distinct ...) for the select list in that case. Also, it can’t work when group by and distinct are combined.

[beikov]

Thanks for testing! I think these cases are covered by the following testsuite methods:

• testCountWithHavingClauseThatCannotBeExpressedAsWhereClause is covered by com.blazebit.persistence.testsuite.CountQueryTest#countQueryFromHavingQuery
• testCountWithGroupByClauseThatCannotBeRemoved is covered by com.blazebit.persistence.testsuite.CountQueryTest#countQueryWithGroupBy
• testCountDistinctWithGroupByClauseThatCannotBeRemoved is covered by com.blazebit.persistence.testsuite.CountQueryTest#countQueryWithDistinct

[jwgmeligmeyling]

I’ve just done a couple of tests in CountQueryTest against the current master, and they all worked flawlessly.

The scenario’s I’ve tested:

• Having clause that cannot be expressed as a where clause, and thus requires a subquery
• Group by clause that is cardinality increasing
• Count distinct on multiple columns

My scenario’s were as follows, if you’re interested in any of them let me know, then I’ll provide them as patch. 👍 I wasn’t sure for which of these scenarios tests already exist.

@Test
public void testCountWithHavingClauseThatCannotBeExpressedAsWhereClause() {
    CriteriaBuilder<Tuple> crit = cbf.create(em, Tuple.class)
            .from(Person.class, "owner")
            .leftJoin("owner.ownedDocuments", "d")
            .select("owner.id")
            .select("count(d.id)")
            .groupBy("owner.id")
            .having("count(d.id)").gtExpression("3");

    final Long expected = (long) crit.getResultList().size();
    final Long actual = crit.getCountQuery().getSingleResult();
    assertEquals(expected, actual);
}

@Test
public void testCountWithGroupByClauseThatCannotBeRemoved() {
    CriteriaBuilder<Tuple> crit = cbf.create(em, Tuple.class)
            .from(Person.class, "owner")
            .leftJoin("owner.ownedDocuments", "d")
            .select("count(d.id)")
            .groupBy("CASE WHEN d.id < 2 THEN TRUE ELSE FALSE END");

    final Long expected = (long) crit.getResultList().size();
    final Long actual = crit.getCountQuery().getSingleResult();
    assertEquals(expected, actual);
}


@Test
public void testCountDistinctWithGroupByClauseThatCannotBeRemoved() {
    CriteriaBuilder<Tuple> crit = cbf.create(em, Tuple.class)
            .from(Person.class, "owner")
            .leftJoin("owner.ownedDocuments", "d")
            .distinct()
            .select("owner.id")
            .select("min(d.id)");

    final Long expected = (long) crit.getResultList().size();
    final Long actual = crit.getCountQuery().getSingleResult();
    assertEquals(expected, actual);
}