[jira] [Assigned] (SPARK-27411) DataSourceV2Strategy should not eliminate subquery

["Wenchen Fan (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/SPARK-27411?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Wenchen Fan reassigned SPARK-27411:
-----------------------------------

    Assignee: Mingcong Han

> DataSourceV2Strategy should not eliminate subquery
> --------------------------------------------------
>
>                 Key: SPARK-27411
>                 URL: https://issues.apache.org/jira/browse/SPARK-27411
>             Project: Spark
>          Issue Type: Bug
>          Components: SQL
>    Affects Versions: 3.0.0
>            Reporter: Mingcong Han
>            Assignee: Mingcong Han
>            Priority: Major
>             Fix For: 3.0.0
>
>
> In DataSourceV2Strategy, it seems we eliminate the subqueries by mistake after normalizing filters. Here is an example:
> We have an sql with a scalar subquery:
> {code:scala}
> val plan = spark.sql("select * from t2 where t2a > (select max(t1a) from t1)")
> plan.explain(true)
> {code}
> And we get the log info of DataSourceV2Strategy:
> {noformat}
> Pushing operators to csv:examples/src/main/resources/t2.txt
> Pushed Filters: 
> Post-Scan Filters: isnotnull(t2a#30)
> Output: t2a#30, t2b#31
> {noformat}
> The `Post-Scan Filters` should contain the scalar subquery, but we eliminate it by mistake.
> {noformat}
> == Parsed Logical Plan ==
> 'Project [*]
> +- 'Filter ('t2a > scalar-subquery#56 [])
>    :  +- 'Project [unresolvedalias('max('t1a), None)]
>    :     +- 'UnresolvedRelation `t1`
>    +- 'UnresolvedRelation `t2`
> == Analyzed Logical Plan ==
> t2a: string, t2b: string
> Project [t2a#30, t2b#31]
> +- Filter (t2a#30 > scalar-subquery#56 [])
>    :  +- Aggregate [max(t1a#13) AS max(t1a)#63]
>    :     +- SubqueryAlias `t1`
>    :        +- RelationV2[t1a#13, t1b#14] csv:examples/src/main/resources/t1.txt
>    +- SubqueryAlias `t2`
>       +- RelationV2[t2a#30, t2b#31] csv:examples/src/main/resources/t2.txt
> == Optimized Logical Plan ==
> Filter (isnotnull(t2a#30) && (t2a#30 > scalar-subquery#56 []))
> :  +- Aggregate [max(t1a#13) AS max(t1a)#63]
> :     +- Project [t1a#13]
> :        +- RelationV2[t1a#13, t1b#14] csv:examples/src/main/resources/t1.txt
> +- RelationV2[t2a#30, t2b#31] csv:examples/src/main/resources/t2.txt
> == Physical Plan ==
> *(1) Project [t2a#30, t2b#31]
> +- *(1) Filter isnotnull(t2a#30)
>    +- *(1) BatchScan[t2a#30, t2b#31] class org.apache.spark.sql.execution.datasources.v2.csv.CSVScan
> {noformat}



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