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https://issues.apache.org/jira/browse/PIG-3144?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13799470#comment-13799470
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Koji Noguchi commented on PIG-3144:
-----------------------------------
FYI, I'm trying to revert the change from this jira at PIG-3492.
> Erroneous map entry alias resolution leading to "Duplicate schema alias"
> errors
> -------------------------------------------------------------------------------
>
> Key: PIG-3144
> URL: https://issues.apache.org/jira/browse/PIG-3144
> Project: Pig
> Issue Type: Bug
> Affects Versions: 0.11, 0.10.1
> Reporter: Kai Londenberg
> Assignee: Jonathan Coveney
> Fix For: 0.12.0, 0.11.1
>
> Attachments: PIG-3144-0.patch, PIG-3144-1-branch-0.11.patch,
> PIG-3144-1.patch
>
>
> The following code illustrates a problem concerning alias resolution in pig
> The schema of D2 will incorrectly be described as containing two "age"
> fields. And the last step in the following script will lead to a "Duplicate
> schema alias" error message.
> I only encountered this bug when using aliases for map fields.
> {code}
> DATA = LOAD 'file:///whatever' as (a:map[chararray], b:chararray);
> D1 = FOREACH DATA GENERATE a#'name' as name, a#'age' as age, b;
> D2 = FOREACH D1 GENERATE name, age, b;
> DESCRIBE D2;
> {code}
> Output:
> {code}
> D2: {
> age: chararray,
> age: chararray,
> b: chararray
> }
> {code}
> {code}
> D3 = FOREACH D2 GENERATE *;
> DESCRIBE D3;
> {code}
> Output:
> {code}
> <file file:///.../pig-bug-example.pig, line 20, column 16> Duplicate schema
> alias: age
> {code}
> This error occurs in this form in Apache Pig version 0.11.0-SNAPSHOT (r6408).
> A less severe variant of this bug is also present in pig 0.10.1. In 0.10.1,
> the "Duplicate schema alias" error message won't occur, but the schema of D2
> (see above) will still have wrong duplicate alias entries.
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