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https://issues.apache.org/jira/browse/HIVE-2843?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13242373#comment-13242373
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David Worms commented on HIVE-2843:
-----------------------------------
Thiruvel,
I have been thinking to name it "implode" at first. Then i step back because of
2 reasons:
1. there are potentially different map implementations, for example, i'm
personally intensively using the toOrderedMap UDAF which in my case would be
much faster than using an 'order by' clause in my query.
2. implode is not restricted to map, and actually would probably be more
appropriate for an array conversion.
What do you think?
> UDAF to convert an aggregation to a map
> ---------------------------------------
>
> Key: HIVE-2843
> URL: https://issues.apache.org/jira/browse/HIVE-2843
> Project: Hive
> Issue Type: New Feature
> Components: UDF
> Affects Versions: 0.9.0
> Reporter: David Worms
> Priority: Minor
> Labels: features, udf
>
> 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/
> If you are interested by my proposal, I'll take the time to update this issue
> while following the guideline posted on the wiki to create an appropriate
> path.
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