Lai Zhou created CALCITE-4161:
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Summary: MergeJoin algorithm should not assume inputs sorted in
ascending order
Key: CALCITE-4161
URL: https://issues.apache.org/jira/browse/CALCITE-4161
Project: Calcite
Issue Type: Bug
Components: core, linq4j
Affects Versions: 1.24.0
Reporter: Lai Zhou
given a sql:
{code:java}
select id,first_name,vs.specialty_id from vets join vet_specialties vs on
vets.id = vs.vet_id and vet_id>1 order by id desc limit 100
{code}
the final plan is:
{code:java}
EnumerableCalc(expr#0..3=[{inputs}], proj#0..1=[{exprs}], specialty_id=[$t3])
EnumerableLimit(fetch=[100]) EnumerableMergeJoin(condition=[=($0, $2)],
joinType=[inner]) EnumerableSort(sort0=[$0], dir0=[DESC])
EnumerableCalc(expr#0..2=[{inputs}], proj#0..1=[{exprs}])
JdbcToEnumerableConverter JdbcFilter(condition=[>($0, 1)])
JdbcTableScan(table=[[default, vets]]) EnumerableSort(sort0=[$0], dir0=[DESC])
JdbcToEnumerableConverter JdbcFilter(condition=[>($0, 1)])
JdbcTableScan(table=[[default, vet_specialties]])
{code}
The inputs of EnumerableMergeJoin is sorted in descending order，
but the MergeJoinEnumerator just supports inputs sorted in ascending order,
the result is wrong.
I think the MergeJoin should not assume inputs sorted in ascending order,
it should know the inputs sorted order .
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