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From "Santhosh Srinivasan (JIRA)" <j...@apache.org>
Subject [jira] Created: (PIG-866) Pig should support ability to query unique column name when there is no ambiguity
Date Mon, 29 Jun 2009 18:24:47 GMT
Pig should support ability to query unique column name when there is no ambiguity
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                 Key: PIG-866
                 URL: https://issues.apache.org/jira/browse/PIG-866
             Project: Pig
          Issue Type: Improvement
          Components: impl
    Affects Versions: 0.4.0
            Reporter: Santhosh Srinivasan
             Fix For: 0.4.0


Currently, the default alias of a column following a flatten contains the disambiguator  "::".
 For columns that have a unique name, the "::" disambiguator is not required. Although, Pig
supports column access via the unique name and the disambiguated name, there is no support
to retrieve the unique column name. This is a nice to have enhancement. An example below will
illustrate the issue:

{code}
grunt> a = load 'input' as (name, age, gpa); 
grunt> b = group a ALL;
grunt> c = foreach b generate flatten(a);    

grunt> describe c;
c: {a::name: bytearray,a::age: bytearray,a::gpa: bytearray} 

grunt> d = foreach c generate name;          

grunt> describe d;                           
d: {a::name: bytearray} 
{code}

In the example shown above, although the column name is allowed in the relation 'd', the name
of the column appears as 'a::name' in the schema. The workaround for this issue is to use
the AS clause in the foreach. However, this is cumbersome for users and its something that
can be fixed within Pig.

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