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Posted to commits@beam.apache.org by "Amit Sela (JIRA)" <ji...@apache.org> on 2017/01/04 19:11:58 UTC

[jira] [Updated] (BEAM-649) Cache any PCollection implementation if accessed more than once

     [ https://issues.apache.org/jira/browse/BEAM-649?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Amit Sela updated BEAM-649:
---------------------------
    Summary: Cache any PCollection implementation if accessed more than once  (was: Pipeline "actions" should use foreachRDD via ParDo.)

> Cache any PCollection implementation if accessed more than once
> ---------------------------------------------------------------
>
>                 Key: BEAM-649
>                 URL: https://issues.apache.org/jira/browse/BEAM-649
>             Project: Beam
>          Issue Type: Improvement
>          Components: runner-spark
>            Reporter: Amit Sela
>            Assignee: Jean-Baptiste Onofré
>
> Spark will execute a pipeline ONLY if it's triggered by an action (batch) / output operation (streaming) - http://spark.apache.org/docs/1.6.2/streaming-programming-guide.html#output-operations-on-dstreams.
> Currently, such actions in Beam are mostly implemented via ParDo, and translated by the runner as a Map transformation (via mapPartitions).
> The runner overcomes this by "forcing" actions on untranslated leaves.
> While this is OK, it would be better in some cases, e.g., Sinks, to apply the same ParDo translation but with foreach/foreachRDD instead of foreachPartition/mapPartitions.



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