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From "Giuseppe Santoro (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (PIG-3619) Provide XPath function
Date Sat, 13 Sep 2014 10:39:33 GMT

     [ https://issues.apache.org/jira/browse/PIG-3619?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Giuseppe Santoro updated PIG-3619:
----------------------------------
    Attachment: xpath2.patch

I have tried to use this UDF but I get some exceptions related to the Function Mapping definition.
You define here just one parameter while there are at least two mandatory parameters and one
optional. I have fixed that issue in my new patch xpath2.patch you can find attached to this
ticket. I have been running this UDF with hundreds of XPath queries and it works really well
even with the optional parameter.

> Provide XPath function
> ----------------------
>
>                 Key: PIG-3619
>                 URL: https://issues.apache.org/jira/browse/PIG-3619
>             Project: Pig
>          Issue Type: Improvement
>          Components: piggybank
>            Reporter: Saad Patel
>            Assignee: Saad Patel
>             Fix For: 0.13.0
>
>         Attachments: xpath.patch, xpath2.patch
>
>
> Xml is often loaded using XMLLoader with a record boundary tag as one of the parameters.
A common use case is to then extract data from those records. XPath would allow those extractions
to be done very easily. I'm  proposing a patch that adds simple XPath support as a UDF.
> Example usage of this the XPath UDF would be:
> {code}
> extractions = FOREACH xmlrecords GENERATE XPath(record, 'book/author'), XPath(record,
'book/title');
> {code}
> The proposed UDF also caches the last xml document. This is helpful for improving performance
when multiple consecutive xpath extractions on the same xml document, such as the example
above. 



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