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https://issues.apache.org/jira/browse/PIG-159?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12596414#action_12596414
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Alan Gates commented on PIG-159:
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In response to Pi's comment above
(https://issues.apache.org/jira/browse/PIG-159?focusedCommentId=12595200#action_12595200)
on column selection in loading. I agree:
* in the future we should expand load to include allowing column selection
* we should design our syntax in a way that does not preclude this, though we
need not design the column selection syntax now
* we should do this after the types branch changes.
My changes to the LoadFunc interface to include the function fieldsToRead
(which can pass a schema to the load function indicating which fields it should
read) is a step in this direction as it will allow pig to pass information to
the load function to tell it what columns are desired.
> Make changes to the parser to support new types functionality
> -------------------------------------------------------------
>
> Key: PIG-159
> URL: https://issues.apache.org/jira/browse/PIG-159
> Project: Pig
> Issue Type: Sub-task
> Components: impl
> Reporter: Alan Gates
> Assignee: Alan Gates
>
> In order to support the new types functionality described in
> http://wiki.apache.org/pig/PigTypesFunctionalSpec, the parse needs to change
> in the following ways:
> 1) AS needs to support types in addition to aliases. So where previously it
> was legal to say:
> a = load 'myfile' as a, b, c;
> it will now also be legal to say
> a = load 'myfile' as a integer, b float, c chararray;
> 2) Non string constants need to be supported. This includes non-string
> atomic types (integer, long, float, double) and the non-atomic types bags,
> tuples, and maps.
> 3) A cast operator needs to be added so that fields can be explicitly casted.
> 4) Changes to DEFINE, to allow users to declare arguments and return types
> for UDFs
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