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From Apache Wiki <wikidi...@apache.org>
Subject [Pig Wiki] Update of "PigExecutionModel" by Shravan Narayanamurthy
Date Wed, 30 Jan 2008 01:23:14 GMT
Dear Wiki user,

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

------------------------------------------------------------------------------
   1. The mapping from logical operators to physical operators aims at preserving isomorphism
of computation trees. Hence, most logical operators have their counterpart in physical operators.
For instance, a logical FILTER will be translated into a physical FILTER. See translation
scheme below.
   1. These are the following exceptions:
      1. Logical Cogroup to be translated into a Physical LocalRearrange and GlobalRearrange.
- 
+     2. Chris mentioned that even Algebraic Functions are exceptions to this.
  
  === Logical to Physical Translation Scheme ===
  
@@ -161, +161 @@

  
  attachment:FILTERTranslation.png
  
+ === Comments ===
+ 
+ The Physical plan and the Logical Plan were not clear to me probably because of the nested
query plan thingy. I think we need to find a better way to draw this because, the conditional
expression is an attribute of the filter and not an input to filter.
+ 

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