[
https://issues.apache.org/jira/browse/PIG-171?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12606518#action_12606518
]
Daniel Dai commented on PIG-171:
--------------------------------
If we use "SAMPLE" instead of "LIMIT" for first k output, people will expect
this is a fairly random sample. They may not notice that the sample they've got
is just a "first k". To me, it seems to be more confusing. What Pi suggested is
a dedicated "SAMPLE" operator. It should be a random sample and should have a
different implementation. How do you think?
> Top K
> -----
>
> Key: PIG-171
> URL: https://issues.apache.org/jira/browse/PIG-171
> Project: Pig
> Issue Type: New Feature
> Reporter: Amir Youssefi
>
> Frequently, users are interested on Top results (especially Top K rows) .
> This can be implemented efficiently in Pig /Map Reduce settings to deliver
> rapid results and low Network Bandwidth/Memory usage.
>
> Key point is to prune all data on the map side and keep only small set of
> rows with Top criteria . We can do it in Algebraic function (combiner) with
> multiple value output. Only a small data-set gets out of mapper node.
> The same idea is applicable to solve variants of this problem:
> - An Algebraic Function for 'Top K Rows'
> - An Algebraic Function for 'Top K' values ('Top Rank K' and 'Top Dense
> Rank K')
> - TOP K ORDER BY.
> Another words implementation is similar to combiners for aggregate functions
> but instead of one value we get multiple ones.
> I will add a sample implementation for Top K Rows and possibly TOP K ORDER BY
> to clarify details.
--
This message is automatically generated by JIRA.
-
You can reply to this email to add a comment to the issue online.
