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From "Daniel Dai (JIRA)" <j...@apache.org>
Subject [jira] Created: (PIG-1326) Logical Optimizer: Unique sort rule
Date Mon, 22 Mar 2010 23:39:27 GMT
Logical Optimizer: Unique sort rule
-----------------------------------

                 Key: PIG-1326
                 URL: https://issues.apache.org/jira/browse/PIG-1326
             Project: Pig
          Issue Type: New Feature
          Components: impl
    Affects Versions: 0.6.0
            Reporter: Daniel Dai
            Assignee: Daniel Dai


We do not have unique sort in Pig Latin. If user want to do a unique sort, they have to do
a distinct followed by a sort. This is two map-reduce jobs. However, we can identify some
patterns in the script. If the user intend to do a unique sort, we can merge two map-reduce
jobs into one. This rule need physical layer support to deal with unique sort.

Example:
B = distinct A;
C = sort B by *;

=> C = uniq sort A by *;

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