[SPARK-37292] Removes outer join if it only has DISTINCT on streamed side with alias

• Type: Improvement
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 3.3.0
• Fix Version/s: 3.3.0
• Component/s: SQL
• Assignee: Yuming Wang
• Reporter: Yuming Wang
• Created: 11/Nov/21 13:28
• Updated: 10/Mar/22 02:36
• Resolved: 12/Nov/21 05:38

Description

    spark.range(200L).selectExpr("id AS a").createTempView("t1")
    spark.range(300L).selectExpr("id AS b").createTempView("t2")
    spark.sql("SELECT DISTINCT a AS newAlias FROM t1 LEFT JOIN t2 ON a = b").explain(true)

Expected optimized plan:

== Optimized Logical Plan ==
Aggregate [newAlias#8L], [newAlias#8L]
+- Project [id#0L AS newAlias#8L]
   +- Range (0, 200, step=1, splits=Some(2))

Issue Links

• is cloned by: SPARK-38489 Aggregate.groupOnly support foldable expressions
• links to: [Github] Pull Request #34557 (wangyum)
• links to: [Github] Pull Request #34573 (wangyum)