[HIVE-2843] UDAF to convert an aggregation to a map

• Type: New Feature
• Status: Open
• Priority: Minor
• Resolution: Unresolved
• Affects Version/s: 0.9.0, 0.10.0
• Component/s: UDF
• Labels: UDAF features udf
• Assignee: Unassigned
• Reporter: David Worms
• Created: 07/Mar/12 01:10
• Updated: 03/Jul/14 14:11

Description

I propose the addition of two new Hive UDAF to help with maps in Apache Hive. The source code is available on GitHub at https://github.com/wdavidw/hive-udf in two Java classes: "UDAFToMap" and "UDAFToOrderedMap". The first function convert an aggregation into a map and is internally using a Java `HashMap`. The second function extends the first one. It convert an aggregation into an ordered map and is internally using a Java `TreeMap`. They both extends the `AbstractGenericUDAFResolver` class.

Also, I have covered the motivations and usages of those UDAF in a blog post at http://adaltas.com/blog/2012/03/06/hive-udaf-map-conversion/

The full patch is available with tests as well.