[jira] [Commented] (SPARK-6830) Memoize frequently queried vals in RDD, such as numPartitions, count etc.

["Sun Rui (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/SPARK-6830?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15033325#comment-15033325 ] 

Sun Rui commented on SPARK-6830:
--------------------------------

Quote from Reynold:
actually maybe it's a bad idea to blindly cache count result, since the query plan can be nondeterministic. For example you might run a query "select * where time > now()".

> Memoize frequently queried vals in RDD, such as numPartitions, count etc.
> -------------------------------------------------------------------------
>
>                 Key: SPARK-6830
>                 URL: https://issues.apache.org/jira/browse/SPARK-6830
>             Project: Spark
>          Issue Type: Improvement
>          Components: SparkR
>            Reporter: Shivaram Venkataraman
>            Priority: Minor
>              Labels: Starter
>
> We should memoize frequently queried vals in RDD, such as numPartitions, count etc.
> While using SparkR in RStudio, the `count` function seems to be called frequently by the IDE – I think this is to show some stats about variables in the workspace etc. but this is not great in SparkR as we trigger a job every time count is called.
> Memoization would help in this case, but we should also see if there is some better way to interact with RStudio.



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