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From "Pi Song (JIRA)" <j...@apache.org>
Subject [jira] Commented: (PIG-158) Rework logical plan
Date Sun, 13 Apr 2008 14:13:09 GMT

    [ https://issues.apache.org/jira/browse/PIG-158?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12588393#action_12588393

Pi Song commented on PIG-158:


Back to the latest patch v3, I've got more questions and comments:-
1) In COGroup why is that mInputs an ArrayList<String> ? Shouldn't it be ArrayList<LogicalOperator>
? How do you plan to get inputs out of strings?
2) Why LOSort has getInput() but LOFilter and LOSplit don't have? All of them have 1 bag input
+ expression input(s).
3) I think the PigTypeDesign documentation in Wiki is out-of-date. Is LOProject a replacement
for FieldExpression?
4) What is the right way to get a column name or a column index from LOProject (if a column
name is known or a column index is known) ? At the moment LOProject maintains "List<String>
projection" which seems to contain column names. If I refer to columns by $0,$1,$2, ... ,
what will be stored in this string list?
5) How to handle algebraic functions (takes bag, outputs dataatom) in the new type design.
I haven't seen such operators yet.
6) Should all the relational operators share the same RelationalOperator parent class? All
of them share the same characteristic that is taking a bag of tuples as input and outputing
a bag of tuples)
7) All the relational operators should always have getType() = DataType.BAG ?
8) What are setSchema(), getSchema() in relational operators? Do they mean schema of tuples
in the output bag?
9) How about setSchema(), getSchema() in expression operators?
10) (I believe you know this) Do we plan to have a bag containing other datatypes other than

> 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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