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Posted to issues@spark.apache.org by "Kyle Prifogle (JIRA)" <ji...@apache.org> on 2018/07/18 17:43:01 UTC
[jira] [Commented] (SPARK-12449) Pushing down arbitrary logical
plans to data sources
[ https://issues.apache.org/jira/browse/SPARK-12449?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16548140#comment-16548140 ]
Kyle Prifogle commented on SPARK-12449:
---------------------------------------
What happened to this initiative? I came here trying to figure out why ".limit(10)" seemed to scan the entire table.
Is slow down in some of this (seemingly critical) work an indication that the breaks have been put on open source spark and that databricks run time is the only future?
> Pushing down arbitrary logical plans to data sources
> ----------------------------------------------------
>
> Key: SPARK-12449
> URL: https://issues.apache.org/jira/browse/SPARK-12449
> Project: Spark
> Issue Type: Improvement
> Components: SQL
> Reporter: Stephan Kessler
> Priority: Major
> Attachments: pushingDownLogicalPlans.pdf
>
>
> With the help of the DataSource API we can pull data from external sources for processing. Implementing interfaces such as {{PrunedFilteredScan}} allows to push down filters and projects pruning unnecessary fields and rows directly in the data source.
> However, data sources such as SQL Engines are capable of doing even more preprocessing, e.g., evaluating aggregates. This is beneficial because it would reduce the amount of data transferred from the source to Spark. The existing interfaces do not allow such kind of processing in the source.
> We would propose to add a new interface {{CatalystSource}} that allows to defer the processing of arbitrary logical plans to the data source. We have already shown the details at the Spark Summit 2015 Europe [https://spark-summit.org/eu-2015/events/the-pushdown-of-everything/]
> I will add a design document explaining details.
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