[FLINK-3504] Join fails while have expression inside join condition.

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Component/s: Table SQL / API
• Assignee: Fabian Hueske
• Reporter: Chengxiang Li
• Created: 25/Feb/16 03:12
• Updated: 01/Mar/16 08:05
• Resolved: 01/Mar/16 08:05

Description

    val ds1 = CollectionDataSets.get3TupleDataSet(env).as('a, 'b, 'c)
    val ds2 = CollectionDataSets.get5TupleDataSet(env).as('d, 'e, 'f, 'g, 'h)
    val joinT = ds1.join(ds2).filter('a + 3 === 'd).select('c, 'g)

This query would throw exception:

Caused by: org.apache.flink.api.table.TableException: Joins should have at least one equality condition
	at org.apache.flink.api.table.plan.rules.dataset.DataSetJoinRule.convert(DataSetJoinRule.scala:57)
	at org.apache.calcite.rel.convert.ConverterRule.onMatch(ConverterRule.java:116)
	at org.apache.calcite.plan.volcano.VolcanoRuleCall.onMatch(VolcanoRuleCall.java:228)
	... 44 more

There are 2 issues here:

1. DataSetJoinRule does not support expression inside join condition.
2. JoinPushExpressionsRulewould add a Project to calculate expression value before Join, so the join condition does not include expression any more, however, it's not returned after the logical optimization.

Issue Links

• relates to: FLINK-3508 Add more test cases to verify the rules of logical plan optimization