[jira] Commented: (PIG-427) casting parameters of a UDF

["Olga Natkovich (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/PIG-427?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12632422#action_12632422 ] 

Olga Natkovich commented on PIG-427:
------------------------------------

Hi Shravan,

Thanks for the patch. I have a couple of comments:

(1) We don't support BOOLEAN is type in the language so we don't need it in the mapping
(2) I don't think we should cast numeric types to chararrays because we don't know what encoding to use
(3) I don't think we should cast bytearrays to anything implicitely since we don't know what is a safe cast in this case
(4) I think that if multiple function get the same score, we should say that it is ambiguous and ask for explicit cast. For instance, we have 2 functions (int, float) and (float, int) and the input (int, int) - we should say that we can't choose.

> casting parameters of a UDF
> ---------------------------
>
>                 Key: PIG-427
>                 URL: https://issues.apache.org/jira/browse/PIG-427
>             Project: Pig
>          Issue Type: Improvement
>    Affects Versions: types_branch
>            Reporter: Olga Natkovich
>            Assignee: Shravan Matthur Narayanamurthy
>             Fix For: types_branch
>
>         Attachments: 427.patch
>
>
> Currently if we have a UDF that declares via getArgToFuncMapping that it can only handle a subset of types, passing any other types to the function would result in an error. However, some types can be promoted to others and it would be useful if typechecker to perform best fit cast. For instance, if the input parameter has type of Long and the UDF support Int and Double, the code should cast the paraneter into Double.
> This would be very useful for conversion of the UDFs from the piigybank to the new code.

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