[jira] [Resolved] (PIG-2883) MapKeysToBag and more UDFs to manipulate maps

["Dmitriy V. Ryaboy (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/PIG-2883?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Dmitriy V. Ryaboy resolved PIG-2883.
------------------------------------

    Resolution: Duplicate


Trunk has KEYSET, VALUESET udfs for this very purpose.
                
> MapKeysToBag and more UDFs to manipulate maps
> ---------------------------------------------
>
>                 Key: PIG-2883
>                 URL: https://issues.apache.org/jira/browse/PIG-2883
>             Project: Pig
>          Issue Type: Wish
>          Components: piggybank
>    Affects Versions: 0.10.0
>            Reporter: Adam Kawa
>            Priority: Trivial
>   Original Estimate: 3h
>  Remaining Estimate: 3h
>
> HBaseStorage allows a user to load many HBase columns by specifying the prefix. The problem is to access such columns later, if their names are dynamically created and hold some meaningful information, which you want to process as well (it seems to be relatively common). 
> Quick example:
> {code}
> User = LOAD 'hbase://user' USING HBaseStorage('friends:*', '-loadKey true') AS (username:bytearray, friendMap:map[]);
> UserAndFriend = FOREACH User GENERATE username, friendMap#'What_should_I_to_put_here?';
> {code}
> It would be convenient to easily get the full list of key/value pairs (or just keys or values) from a map (something like MapKeysToBag, MapValuesToBag, MapEntriesToBag UDFs). Having such UFDs, we may FLATTEN returned bag and generate a relation that contains unnested keys or values extracted from the map e.g.:
> {code}
> UserAndFriend = FOREACH Users GENERATE username, FLATTEN(MapKeysToTuple(friendMap)) AS friendUsername;
> {code}
> I have already implemented such UDFs (here is repo: https://github.com/kawaa/Pigitos and here is a fancy example: http://bit.ly/Sf2KCP). I would love to add it to Piggybank (I have not found such functionality there).
> If you think that it is useful and missing, I can prepare a patch as soon as possible. Please let me know.

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