[jira] Commented: (PIG-1423) Suggest to add clear command in grunt to clear the relation variable

["Olga Natkovich (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/PIG-1423?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12892992#action_12892992 ] 

Olga Natkovich commented on PIG-1423:
-------------------------------------

I am not sure I like the idea of unsetting variables as a grant command. I think it can cause more confusion and generate more problems then it would help to solve. I think the right way to solve this problem is to define scope for variables as part of our turing complete effort. 

If we have an agreement on this, I would like to unlinik it from 0.8.0 release.



> Suggest to add clear command in grunt to clear the relation variable
> --------------------------------------------------------------------
>
>                 Key: PIG-1423
>                 URL: https://issues.apache.org/jira/browse/PIG-1423
>             Project: Pig
>          Issue Type: New Feature
>          Components: grunt
>    Affects Versions: 0.8.0
>            Reporter: Jeff Zhang
>            Assignee: Jeff Zhang
>             Fix For: 0.8.0
>
>         Attachments: PIG-1423.patch
>
>
> The relation name in pig script can been considered as variable of programming language. One risk of the current grunt is that user may use the previous defined relation name by typo after a long period of work on grunt. And it is difficult for users to track this problem.  E.g. the following red "students" is not the user intend to use, but here grunt won't throw any error meesage.
> students = load 'a.txt';
> ....
> student = load 'b.txt';
> result = foreach {color:red}students{color} generate $0;
> The clear command is to clear the variable defined before, then if users use the relation name defined before, grunt will throw error message. And this command also will be useful to let user reuse the relation names especially when he's doing lots of experiments for one specific task.

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