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From "Shravan Matthur Narayanamurthy (JIRA)" <j...@apache.org>
Subject [jira] Commented: (PIG-158) Rework logical plan
Date Mon, 07 Apr 2008 18:33:24 GMT

    [ https://issues.apache.org/jira/browse/PIG-158?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12586491#action_12586491
] 

Shravan Matthur Narayanamurthy commented on PIG-158:
----------------------------------------------------

Somehow, I think I am missing the point. I still don't see the difference between instantiating
a new visitor because all we still have is access to w and currentWalker in this design and
the same is available in the other design where we have the current visitor and the newly
instantiated visitor. The difference I see is that the traversal logic is separated out of
the visitor as a walker and composed into the visitor, which seems to be the right thing to
do. Other than that I don't see any difference. I must be missing something.

In the old design, we would do something like this in the LOVisitor for filter:

public void visit(LOFilter f)
{
 ExprPlanVisitor epv = new ExprPlanVisitor(f.getExprPlan());
 epv.visit();
}

Even here, we have access to epv and the current visitor. Can someone please tell me what
can't be done in this case that can be in the visitor/walker?

> Rework logical plan
> -------------------
>
>                 Key: PIG-158
>                 URL: https://issues.apache.org/jira/browse/PIG-158
>             Project: Pig
>          Issue Type: Sub-task
>          Components: impl
>            Reporter: Alan Gates
>            Assignee: Alan Gates
>         Attachments: logical_operators.patch, logical_operators_rev_1.patch, logical_operators_rev_2.patch,
logical_operators_rev_3.patch, visitorWalker.patch
>
>
> Rework the logical plan in line with http://wiki.apache.org/pig/PigExecutionModel

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