[SPARK-22347][PySpark][DOC] Add document to notice users for using udfs with conditional expressions #19617
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retest this please. |
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Test build #83242 has finished for PR 19617 at commit
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HyukjinKwon
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Oct 31, 2017
python/pyspark/sql/functions.py
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| it is present in the query. | ||
| .. note:: The user-defined functions do not support conditional execution by using them with | ||
| SQL conditional expressions such `when` or `if`. The functions still apply on all rows no |
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Looks a tiny typo expressions such `when` or `if`. -> expressions such as `when` or `if`..
| duplicate invocations may be eliminated or the function may even be invoked more times than | ||
| it is present in the query. | ||
| .. note:: The user-defined functions do not support conditional execution by using them with |
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Hm, should we maybe clarify the output itself is correct if it does not cause the runtime failure by the condition? Maybe I am too much worried but think it might mislead the output is incorrect at all.
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Yes. I think this is a valid worry. Thanks.
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Test build #83261 has finished for PR 19617 at commit
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cc @cloud-fan for checking the document too. |
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thanks, merging to master! |
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What changes were proposed in this pull request?
Under the current execution mode of Python UDFs, we don't well support Python UDFs as branch values or else value in CaseWhen expression.
Since to fix it might need the change not small (e.g., #19592) and this issue has simpler workaround. We should just notice users in the document about this.
How was this patch tested?
Only document change.