[jira] [Resolved] (SPARK-1669) SQLContext.cacheTable() should be idempotent

["Michael Armbrust (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/SPARK-1669?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Michael Armbrust resolved SPARK-1669.
-------------------------------------

       Resolution: Fixed
    Fix Version/s: 1.1.0
                   1.0.1

https://github.com/apache/spark/pull/1183

> SQLContext.cacheTable() should be idempotent
> --------------------------------------------
>
>                 Key: SPARK-1669
>                 URL: https://issues.apache.org/jira/browse/SPARK-1669
>             Project: Spark
>          Issue Type: Improvement
>          Components: SQL
>    Affects Versions: 1.0.0
>            Reporter: Cheng Lian
>            Assignee: Cheng Lian
>              Labels: cache, column
>             Fix For: 1.0.1, 1.1.0
>
>
> Calling {{cacheTable()}} on some table {{t}} multiple times causes table {{t}} to  be cached multiple times. This semantics is different from {{RDD.cache()}}, which is idempotent.
> We can check whether a table is already cached by checking:
> # whether the structure of the underlying logical plan of the table is matches the pattern {{Subquery(\_, SparkLogicalPlan(inMem @ InMemoryColumnarTableScan(_, _)))}}
> # whether {{inMem.cachedColumnBuffers.getStorageLevel.useMemory}} is true



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