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https://issues.apache.org/jira/browse/PIG-1693?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13016158#comment-13016158
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Thejas M Nair commented on PIG-1693:
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bq. a) $3.. works for an unspecified number of columns when there is no load
schema ?
Yes, "$3 .." works for unspecified number of columns.
This is similar to the way project-star ("*") works without input schema. Since
pig does not know how many columns would be there, the expansion happens at
runtime. In all other cases, the expansion of the project-range expression
happens is done before query plan is generated.
bq. b) or, $3..$MAX is required ? (so we should be schema aware).
No, this is not required.
> support project-range expression. (was: There needs to be a way in foreach to
> indicate "and all the rest of the fields" )
> -------------------------------------------------------------------------------------------------------------------------
>
> Key: PIG-1693
> URL: https://issues.apache.org/jira/browse/PIG-1693
> Project: Pig
> Issue Type: New Feature
> Components: impl
> Reporter: Alan Gates
> Assignee: Thejas M Nair
> Fix For: 0.9.0
>
> Attachments: PIG-1693.1.patch, PIG-1693.2.patch
>
>
> A common use case we see in Pig is people have many columns in their data and
> they only want to operate on a few of them. Consider for example if before
> storing data with ten columns, the user wants to perform a cast on one column:
> {code}
> ...
> Z = foreach Y generate (int)firstcol, secondcol, thridcol, forthcol,
> fifthcol, sixthcol, seventhcol, eigthcol, ninethcol, tenthcol;
> store Z into 'output';
> {code}
> Obviously this only gets worse as the user has more columns. Ideally the
> above could be transformed to something like:
> {code}
> ...
> Z = foreach Y generate (int)firstcol, "and all the rest";
> store Z into 'output'
> {code}
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