Mihai Budiu created CALCITE-7741:
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Summary: Outer join register incorrect types for their input
collections
Key: CALCITE-7741
URL: https://issues.apache.org/jira/browse/CALCITE-7741
Project: Calcite
Issue Type: Bug
Components: core
Affects Versions: 1.42.0
Reporter: Mihai Budiu
Assignee: Mihai Budiu
A LEFT join will produce nullable output fields for all fields that come from
the RIGHT input, even if the right input does not have nullable fields. This is
correct.
However, a LEFT join in Calcite will register a nullable types for the fields
of the right INPUT in the Rel tree. That is wrong: the output fields of the
join are nullable, but the input field types should not change just because
they are part of a join.
As a concrete example, consider the following query:
{code:java}
select e.ename, d.name from emp as e
left join dept as d on trim(d.name) = 'x {code}
If you check the type of the TRIM function call in the Rel tree, it is
nullable, although its argument is not nullable. Type inference for TRIM
produces a non-nullable type.
This is the plan after Sql2Rel containing the TRIM expression:
{code:java}
LogicalProject(ENAME=[$1], NAME=[$10])
LogicalJoin(condition=[=(TRIM(FLAG(BOTH), ' ', $10), 'x')], joinType=[left])
LogicalTableScan(table=[[CATALOG, SALES, EMP]])
LogicalTableScan(table=[[CATALOG, SALES, DEPT]]) {code}
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