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https://issues.apache.org/jira/browse/PIG-1618?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13003663#comment-13003663
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Xuefu Zhang commented on PIG-1618:
----------------------------------

I think the behavior change was largely due to the way we interpret the schema, 
probably having nothing to do with parser.

It's basically a question of how we treat a schema partially known (unknown). 
It doesn't seem easy to correctly address the issue. However, treating a schema 
partially known as unknown seems fine: user can always use $0 instead of 
"group" to access the known field.

On the other hand, treating flattan( a ) as one field of byte array seems 
misleading.

> Switch to new parser generator technology
> -----------------------------------------
>
>                 Key: PIG-1618
>                 URL: https://issues.apache.org/jira/browse/PIG-1618
>             Project: Pig
>          Issue Type: Improvement
>    Affects Versions: 0.8.0
>            Reporter: Alan Gates
>            Assignee: Xuefu Zhang
>             Fix For: 0.9.0
>
>         Attachments: NewParser-1.patch, NewParser-10.patch, 
> NewParser-11.patch, NewParser-12.patch, NewParser-13.2.patch, 
> NewParser-13.patch, NewParser-14.patch, NewParser-15.patch, 
> NewParser-18.patch, NewParser-19.3.patch, NewParser-19.patch, 
> NewParser-2.patch, NewParser-3.patch, NewParser-3.patch, NewParser-4.patch, 
> NewParser-5.patch, NewParser-6.patch, NewParser-7.patch, NewParser-8.patches, 
> NewParser-9.patch, antlr-3.2.jar, javadoc.patch
>
>
> There are many bugs in Pig related to the parser, particularly to bad error 
> messages.  After review of Java CC we feel these will be difficult to address 
> using that tool.  Also, the .jjt files used by JavaCC are hard to understand 
> and maintain.  
> ANTLR is being reviewed as the most likely choice to move to, but other 
> parsers will be reviewed as well.
> This JIRA will act as an umbrella issue for other parser issues.

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