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https://issues.apache.org/jira/browse/PIG-3941?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Philip (flip) Kromer updated PIG-3941:
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Status: Patch Available (was: Open)
> Piggybank's Over UDF returns an output schema with named fields
> ---------------------------------------------------------------
>
> Key: PIG-3941
> URL: https://issues.apache.org/jira/browse/PIG-3941
> Project: Pig
> Issue Type: Improvement
> Components: piggybank
> Reporter: Philip (flip) Kromer
> Priority: Minor
> Labels: piggybank, schema, udf, window
> Attachments:
> 0001-Over-accepts-a-field-spec-name-and-type-separated-by.patch
>
>
> With attached patch, if Over is constructed with a colon-delimited string
> like 'bob:int', the first part is used to set the return field's name and the
> second part its type. Otherwise, if a type is given the name of the return
> field is set to 'result'.
> {code}
> cities = LOAD 'us_city_pops.tsv' AS (city:chararray, state:chararray,
> pop:int);
> DEFINE IOver
> org.apache.pig.piggybank.evaluation.Over('state_rk:int');
> ranked = FOREACH(GROUP cities BY state) {
> c_ord = ORDER cities BY pop DESC;
> GENERATE FLATTEN(Stitch(c_ord,
> IOver(c_ord, 'rank', -1, -1, 2))); -- beginning (-1) to end (-1) on third
> field (2)
> };
> DESCRIBE ranked;
> -- ranked: {stitched::city: chararray,stitched::state:
> chararray,stitched::pop: int,stitched::state_rk: int}
> DUMP ranked;
> -- ...
> -- (Nashville,Tennessee,609644,2)
> -- (Houston,Texas,2145146,1)
> -- (San Antonio,Texas,1359758,2)
> -- (Dallas,Texas,1223229,3)
> -- (Austin,Texas,820611,4)
> -- ...
> {code}
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