[SPARK-3622] Provide a custom transformation that can output multiple RDDs

• Type: Improvement
• Status: Resolved
• Priority: Major
• Resolution: Not A Problem
• Affects Version/s: 1.1.0
• Component/s: Spark Core
• Assignee: Unassigned
• Reporter: Xuefu Zhang
• Created: 21/Sep/14 05:38
• Updated: 02/Feb/15 19:09
• Resolved: 25/Jan/15 17:33

Description

All existing transformations return just one RDD at most, even for those which takes user-supplied functions such as mapPartitions() . However, sometimes a user provided function may need to output multiple RDDs. For instance, a filter function that divides the input RDD into serveral RDDs. While it's possible to get multiple RDDs by transforming the same RDD multiple times, it may be more efficient to do this concurrently in one shot. Especially user's existing function is already generating different data sets.

This the case in Hive on Spark, where Hive's map function and reduce function can output different data sets to be consumed by subsequent stages.

Issue Links

• is depended upon by: SPARK-3145 Hive on Spark umbrella
• relates to: SPARK-2688 Need a way to run multiple data pipeline concurrently