Github user xccui commented on a diff in the pull request:
https://github.com/apache/flink/pull/4858#discussion_r145863708
--- Diff:
flink-libraries/flink-table/src/main/scala/org/apache/flink/table/plan/rules/dataSet/DataSetJoinRule.scala
---
@@ -41,8 +41,7 @@ class DataSetJoinRule
val joinInfo = join.analyzeCondition
// joins require an equi-condition or a conjunctive predicate with at
least one equi-condition
- // and disable outer joins with non-equality predicates(see FLINK-5520)
- !joinInfo.pairs().isEmpty && (joinInfo.isEqui || join.getJoinType ==
JoinRelType.INNER)
+ !joinInfo.pairs().isEmpty
--- End diff --
The condition is checked three times in `FlinkLogicalJoin`,
`DataSetJoinRule`, and `DataSetJoin`. It brings extra maintenance work every
time we change the validation rule.
---
