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https://issues.apache.org/jira/browse/PIG-2883?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Dmitriy V. Ryaboy resolved PIG-2883.
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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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