Benjamin Kietzman created ARROW-6386:
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Summary: [C++][Documentation] Explicit documentation of null slot
interpretation
Key: ARROW-6386
URL: https://issues.apache.org/jira/browse/ARROW-6386
Project: Apache Arrow
Issue Type: Improvement
Components: C++, Documentation
Reporter: Benjamin Kietzman
Assignee: Benjamin Kietzman
To my knowledge, there isn't explicit documentation on how null slots in an
array should be interpreted. SQL uses Kleene logic, wherein a null is
explicitly an unknown rather than a special value. This yields for example
`(null AND false) -> false`, since `(x AND false) -> false` for all possible
values of x. This is also the behavior of Gandiva's boolean expressions.
By contrast the boolean kernels implement something closer to the behavior of
NaN: `(null AND false) -> null`. I think this is simply an error in the boolean
kernels but in any case I think explicit documentation should be added to
prevent future confusion.
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