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From "Aleksander Eskilson (JIRA)" <j...@apache.org>
Subject [jira] [Created] (SPARK-17939) Spark-SQL Nullability: Optimizations vs. Enforcement Clarification
Date Fri, 14 Oct 2016 14:47:20 GMT
Aleksander Eskilson created SPARK-17939:
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             Summary: Spark-SQL Nullability: Optimizations vs. Enforcement Clarification
                 Key: SPARK-17939
                 URL: https://issues.apache.org/jira/browse/SPARK-17939
             Project: Spark
          Issue Type: Bug
          Components: SQL
    Affects Versions: 2.0.0
            Reporter: Aleksander Eskilson
            Priority: Critical


The notion of Nullability of of StructFields in DataFrames and Datasets creates some confusion.
As has been pointed out previously [1], Nullability is a hint to the Catalyst optimizer, and
is not meant to be a type-level enforcement. Allowing null fields can also help the reader
successfully parse certain types of more loosely-typed data, like JSON and CSV, where null
values are common, rather than just failing. 

There's already been some movement to clarify the meaning of Nullable in the API, but also
some requests for a (perhaps completely separate) type-level implementation of Nullable that
can act as an enforcement contract.

This bug is logged here to discuss and clarify this issue.



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