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From "Apache Spark (JIRA)" <j...@apache.org>
Subject [jira] [Assigned] (SPARK-19093) Cached tables are not used in SubqueryExpression
Date Sat, 07 Jan 2017 00:34:58 GMT

     [ https://issues.apache.org/jira/browse/SPARK-19093?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Apache Spark reassigned SPARK-19093:
------------------------------------

    Assignee: Apache Spark

> Cached tables are not used in SubqueryExpression
> ------------------------------------------------
>
>                 Key: SPARK-19093
>                 URL: https://issues.apache.org/jira/browse/SPARK-19093
>             Project: Spark
>          Issue Type: Bug
>          Components: SQL
>    Affects Versions: 2.0.2, 2.1.0
>            Reporter: Josh Rosen
>            Assignee: Apache Spark
>
> See reproduction at https://databricks-prod-cloudfront.cloud.databricks.com/public/4027ec902e239c93eaaa8714f173bcfc/1903098128019500/2699761537338853/1395282846718893/latest.html
> Consider the following:
> {code}
> Seq(("a", "b"), ("c", "d"))
>   .toDS
>   .write
>   .parquet("/tmp/rows")
> val df = spark.read.parquet("/tmp/rows")
> df.cache()
> df.count()
> df.createOrReplaceTempView("rows")
> spark.sql("""
>   select * from rows cross join rows
> """).explain(true)
> spark.sql("""
>   select * from rows where not exists (select * from rows)
> """).explain(true)
> {code}
> In both plans, I'd expect that both sides of the joins would read from the cached table
for both the cross join and anti join, but the left anti join produces the following plan
which only reads the left side from cache and reads the right side via a regular non-cahced
scan:
> {code}
> == Parsed Logical Plan ==
> 'Project [*]
> +- 'Filter NOT exists#3994
>    :  +- 'Project [*]
>    :     +- 'UnresolvedRelation `rows`
>    +- 'UnresolvedRelation `rows`
> == Analyzed Logical Plan ==
> _1: string, _2: string
> Project [_1#3775, _2#3776]
> +- Filter NOT predicate-subquery#3994 []
>    :  +- Project [_1#3775 AS _1#3775#4001, _2#3776 AS _2#3776#4002]
>    :     +- Project [_1#3775, _2#3776]
>    :        +- SubqueryAlias rows
>    :           +- Relation[_1#3775,_2#3776] parquet
>    +- SubqueryAlias rows
>       +- Relation[_1#3775,_2#3776] parquet
> == Optimized Logical Plan ==
> Join LeftAnti
> :- InMemoryRelation [_1#3775, _2#3776], true, 10000, StorageLevel(disk, memory, deserialized,
1 replicas)
> :     +- *FileScan parquet [_1#3775,_2#3776] Batched: true, Format: Parquet, Location:
InMemoryFileIndex[dbfs:/tmp/rows], PartitionFilters: [], PushedFilters: [], ReadSchema: struct<_1:string,_2:string>
> +- Project [_1#3775 AS _1#3775#4001, _2#3776 AS _2#3776#4002]
>    +- Relation[_1#3775,_2#3776] parquet
> == Physical Plan ==
> BroadcastNestedLoopJoin BuildRight, LeftAnti
> :- InMemoryTableScan [_1#3775, _2#3776]
> :     +- InMemoryRelation [_1#3775, _2#3776], true, 10000, StorageLevel(disk, memory,
deserialized, 1 replicas)
> :           +- *FileScan parquet [_1#3775,_2#3776] Batched: true, Format: Parquet, Location:
InMemoryFileIndex[dbfs:/tmp/rows], PartitionFilters: [], PushedFilters: [], ReadSchema: struct<_1:string,_2:string>
> +- BroadcastExchange IdentityBroadcastMode
>    +- *Project [_1#3775 AS _1#3775#4001, _2#3776 AS _2#3776#4002]
>       +- *FileScan parquet [_1#3775,_2#3776] Batched: true, Format: Parquet, Location:
InMemoryFileIndex[dbfs:/tmp/rows], PartitionFilters: [], PushedFilters: [], ReadSchema: struct<_1:string,_2:string>
> {code}



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