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https://issues.apache.org/jira/browse/PIG-1635?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12914145#action_12914145
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Yan Zhou commented on PIG-1635:
-------------------------------

test-patch results:

     [exec] +1 overall.
     [exec]
     [exec]     +1 @author.  The patch does not contain any @author tags.
     [exec]
     [exec]     +1 tests included.  The patch appears to include 3 new or 
modified tests.
     [exec]
     [exec]     +1 javadoc.  The javadoc tool did not generate any warning 
messages.
     [exec]
     [exec]     +1 javac.  The applied patch does not increase the total number 
of javac compiler warnings.
     [exec]
     [exec]     +1 findbugs.  The patch does not introduce any new Findbugs 
warnings.
     [exec]
     [exec]     +1 release audit.  The applied patch does not increase the 
total number of release audit warnings.

> Logical simplifier does not simplify away constants under AND and OR; after 
> simplificaion the ordering of operands of AND and OR may get changed
> ------------------------------------------------------------------------------------------------------------------------------------------------
>
>                 Key: PIG-1635
>                 URL: https://issues.apache.org/jira/browse/PIG-1635
>             Project: Pig
>          Issue Type: Bug
>          Components: impl
>    Affects Versions: 0.8.0
>            Reporter: Yan Zhou
>            Assignee: Yan Zhou
>            Priority: Minor
>             Fix For: 0.8.0
>
>         Attachments: PIG-1635.patch
>
>
> b = FILTER a by (( f1 > 1) AND (1 == 1))
> or 
> b = FILTER a by ((f1 > 1) OR ( 1==0))
> should be simplified to
> b = FILTER a by f1 > 1;
> Regarding ordering change, an example is that 
> b = filter a by ((f1 is not null) AND (f2 is not null));
> Even without possible simplification, the expression is changed to
> b = filter a by ((f2 is not null) AND (f1 is not null));
> Even though the ordering change in this case, and probably in most other 
> cases, does not create any difference, but for two reasons some users might 
> care about the ordering: if stateful UDFs are used as operands of AND or OR; 
> and if the ordering is intended by the application designer to maximize the 
> chances to shortcut the composite boolean evaluation. 

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