[SPARK-28978 ] Support > 256 args to python udf #26442
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mengxr
approved these changes
Nov 9, 2019
Contributor
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LGTM. Code is much easier to read now. |
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Test build #113481 has finished for PR 26442 at commit
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Test build #113482 has finished for PR 26442 at commit
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Test build #113485 has finished for PR 26442 at commit
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Contributor
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Merged into master. Thanks! |
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What changes were proposed in this pull request?
On the worker we express lambda functions as strings and then eval them to create a "mapper" function. This make the code hard to read & limits the # of arguments a udf can support to 256 for python <= 3.6.
This PR rewrites the mapper functions as nested functions instead of "lambda strings" and allows passing in more than 255 args.
Why are the changes needed?
The jira ticket associated with this issue describes how MLflow uses udfs to consume columns as features. This pattern isn't unique and a limit of 255 features is quite low.
Does this PR introduce any user-facing change?
Users can now pass more than 255 cols to a udf function.
How was this patch tested?
Added a unit test for passing in > 255 args to udf.