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From Apache Wiki <wikidi...@apache.org>
Subject [Pig Wiki] Update of "PigExecutionModel" by Shravan Narayanamurthy
Date Wed, 30 Jan 2008 01:33:40 GMT
Dear Wiki user,

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The following page has been changed by Shravan Narayanamurthy:
http://wiki.apache.org/pig/PigExecutionModel

------------------------------------------------------------------------------
  
  The logical operator co-group would be converted to 3 physical operators the Local Rearrange,
Global Rearrange and Package as shown below:
  
- attachment:Group.jpg
+ attachment:Group.png
  
  There will be a Local Rearrange operator for each input which will aggregate to a Global
Rearrange followed by a Package as shown below:
  
- attachment:GroupPhy.jpg
+ attachment:GroupPhy.png
  
  The Local Rearrange takes the input tuple and outputs a key, value pair with the group field
as the key and the tuple as the value. For eg., (1,R) will be converted to {1,(1,R)}. Also
the tuple is tagged with the input index it originated from. In our case, if (1,R) came from
A it would be tagged 1 and if it was from B it would be tagged 2. 
  

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