Ruben Quesada Lopez created CALCITE-2605:
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Summary: NullPointerException when left outer join implemented
with EnumerableCorrelate
Key: CALCITE-2605
URL: https://issues.apache.org/jira/browse/CALCITE-2605
Project: Calcite
Issue Type: Bug
Affects Versions: 1.17.0
Reporter: Ruben Quesada Lopez
Assignee: Julian Hyde
Fix For: 1.18.0
In the context of a LEFT OUTER JOIN implemented via EnumerableCorrelate, the
generated code for the selector does not check if the right object is null
(which can be, since it is a LEFT join). This situation can lead to a
NullPointerException.
The root cause is located in EnumerableCorrelate::implement method, which
builds the selector expression using a ternary operator whose "if" and "else"
statements are switched:
{code:java}
Expression selector =
EnumUtils.joinSelector(
joinType.returnsJustFirstInput() ? joinType.toJoinType()
: JoinRelType.INNER, physType,
ImmutableList.of(leftResult.physType, rightResult.physType));
{code}
This code works (by coincidence) in the case of an INNER join; but in case of
LEFT, it will incorrectly call EnumUtils.joinSelector(...) with
JoinRelType.INNER instead of JoinRelType.LEFT, which will produce the
problematic generated code. Also, the current code in the context of a SEMI or
ANTI join will throw an IllegalStateException when calling
SemiJoinType::toJoinType.
If I am not mistaken, to fix this we just need to switch the ternary operator
statements:
{code:java}
Expression selector =
EnumUtils.joinSelector(
joinType.returnsJustFirstInput() ? JoinRelType.INNER
: joinType.toJoinType(), physType,
ImmutableList.of(leftResult.physType, rightResult.physType));
{code}
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