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https://issues.apache.org/jira/browse/PIG-158?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12588393#action_12588393
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Pi Song commented on PIG-158:
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Santhosh,
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3) I think the PigTypeDesign documentation in Wiki is out-of-date.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 tuples?
> 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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