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From "Santhosh Srinivasan (JIRA)" <j...@apache.org>
Subject [jira] Commented: (PIG-320) The parser/type checker should use the getSchema method of UDFs to deduce return type/schema
Date Mon, 21 Jul 2008 21:49:31 GMT

    [ https://issues.apache.org/jira/browse/PIG-320?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12615445#action_12615445
] 

Santhosh Srinivasan commented on PIG-320:
-----------------------------------------

UDFs are expression operators that are expected to return a FieldSchema. The schema returned
by outputSchema should always have a single FieldSchema inside. Hence, only the first field
is extracted.

> The parser/type checker should use the getSchema method of UDFs to deduce return type/schema
> --------------------------------------------------------------------------------------------
>
>                 Key: PIG-320
>                 URL: https://issues.apache.org/jira/browse/PIG-320
>             Project: Pig
>          Issue Type: Bug
>          Components: impl
>    Affects Versions: types_branch
>            Reporter: Santhosh Srinivasan
>            Assignee: Santhosh Srinivasan
>             Fix For: types_branch
>
>         Attachments: udf_outputSchema.patch
>
>
> Currently, the parser/type checker uses the getReturnType to deduce the return type of
the user defined function (UDF). This mechanism is satisfactory only for basic types (int,
long, ...); for composite types (tuple, bag), the schema is also required.The abstract class
EvalFunc interface exposes the outputSchema to deduce the return type/schema of the UDF. The
parser/type checker should use this method to figure out the return type/schema of the UDF
and use it appropriately. 

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