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Posted to issues@spark.apache.org by "Takeshi Yamamuro (Jira)" <ji...@apache.org> on 2021/03/30 01:47:00 UTC
[jira] [Resolved] (SPARK-34622) Push down limit through Project
[ https://issues.apache.org/jira/browse/SPARK-34622?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Takeshi Yamamuro resolved SPARK-34622.
--------------------------------------
Fix Version/s: 3.2.0
Assignee: Yuming Wang
Resolution: Fixed
Resolved by https://github.com/apache/spark/pull/31739
> Push down limit through Project
> -------------------------------
>
> Key: SPARK-34622
> URL: https://issues.apache.org/jira/browse/SPARK-34622
> Project: Spark
> Issue Type: Improvement
> Components: SQL
> Affects Versions: 3.2.0
> Reporter: Yuming Wang
> Assignee: Yuming Wang
> Priority: Major
> Fix For: 3.2.0
>
>
> We will insert a Project if the Join output is not match the LocalLimit. We can not push down limit through join in this case. For example:
> {code:scala}
> spark.sql("create table t1(a int, b int, c int) using parquet")
> spark.sql("create table t2(x int, y int, z int) using parquet")
> spark.sql("select a from t1 left join t2 on a = x and b = y limit 5").explain("cost")
> {code}
> Current:
> {noformat}
> == Optimized Logical Plan ==
> GlobalLimit 5
> +- LocalLimit 5
> +- Project [a#0]
> +- Join LeftOuter, ((a#0 = x#3) AND (b#1 = y#4))
> :- Project [a#0, b#1]
> : +- Relation default.t1[a#0,b#1,c#2] parquet
> +- Project [x#3, y#4]
> +- Filter (isnotnull(x#3) AND isnotnull(y#4))
> +- Relation default.t2[x#3,y#4,z#5] parquet
> {noformat}
> Excepted:
> {noformat}
> == Optimized Logical Plan ==
> GlobalLimit 5
> +- LocalLimit 5
> +- Project [a#0]
> +- Join LeftOuter, ((a#0 = x#3) AND (b#1 = y#4))
> :- LocalLimit 5
> : +- Project [a#0, b#1]
> : +- Relation default.t1[a#0,b#1,c#2] parquet
> +- Project [x#3, y#4]
> +- Filter (isnotnull(x#3) AND isnotnull(y#4))
> +- Relation default.t2[x#3,y#4,z#5] parquet
> {noformat}
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