Ruben Q L created CALCITE-6087:
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Summary: EnumerableSortedAggregate returns incorrect result when
input is empty
Key: CALCITE-6087
URL: https://issues.apache.org/jira/browse/CALCITE-6087
Project: Calcite
Issue Type: Bug
Components: core
Affects Versions: 1.35.0
Reporter: Ruben Q L
Performing a MAX on an empty table (or on a table where we apply a filter which
does not return any value) shall return NULL, we can verify this with our
"standard" {{EnumerableAggregate}} operator:
{code:java}
@Test void enumerableAggregateOnEmptyInput() {
tester(false, new HrSchema())
.query("select max(deptno) as m from emps where deptno>100")
.explainContains(
"EnumerableAggregate(group=[{}], m=[MAX($1)])\n"
+ " EnumerableCalc(expr#0..4=[{inputs}], expr#5=[100],
expr#6=[>($t1, $t5)], proj#0..4=[{exprs}], $condition=[$t6])\n"
+ " EnumerableTableScan(table=[[s, emps]])")
.returnsOrdered("m=null");
}
{code}
However, if we use {{Hook.PLANNER}} to force the aggregation to be implemented
via {{EnumerableSortedAggregate}} on the same query:
{code:java}
@Test void enumerableSortedAggregateOnEmptyInput() {
tester(false, new HrSchema())
.query("select max(deptno) as m from emps where deptno>100")
.withHook(Hook.PLANNER, (Consumer<RelOptPlanner>) planner -> {
planner.removeRule(EnumerableRules.ENUMERABLE_AGGREGATE_RULE);
planner.addRule(EnumerableRules.ENUMERABLE_SORTED_AGGREGATE_RULE);
})
.explainContains(
"EnumerableSortedAggregate(group=[{}], m=[MAX($1)])\n"
+ " EnumerableCalc(expr#0..4=[{inputs}], expr#5=[100],
expr#6=[>($t1, $t5)], proj#0..4=[{exprs}], $condition=[$t6])\n"
+ " EnumerableTableScan(table=[[s, emps]])")
.returnsOrdered("m=null");
}
{code}
It fails, because the EnumerableSortedAggregate returns an empty result set
rather than NULL:
{noformat}
java.lang.AssertionError:
Expected: "m=null"
but: was ""
{noformat}
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