[
https://issues.apache.org/jira/browse/ARROW-6386?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
Ben Kietzman closed ARROW-6386.
-------------------------------
Resolution: Resolved
Interpretation of nulls will be left open for individual kernels.
https://github.com/apache/arrow/pull/5771 adds explicit Kleene logic overloads
of the boolean kernels, allowing SQL compatible behavior in dataset filter
expressions.
> [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: Ben Kietzman
> Assignee: Ben Kietzman
> Priority: Major
> Labels: pull-request-available
> Fix For: 0.16.0
>
> Time Spent: 50m
> Remaining Estimate: 0h
>
> 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.
--
This message was sent by Atlassian Jira
(v8.3.4#803005)
