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https://issues.apache.org/jira/browse/ARROW-62?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17657163#comment-17657163
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Rok Mihevc commented on ARROW-62:
---------------------------------
This issue has been migrated to [issue
#15479|https://github.com/apache/arrow/issues/15479] on GitHub. Please see the
[migration documentation|https://github.com/apache/arrow/issues/14542] for
further details.
> Format: Are the nulls bits 0 or 1 for null values?
> --------------------------------------------------
>
> Key: ARROW-62
> URL: https://issues.apache.org/jira/browse/ARROW-62
> Project: Apache Arrow
> Issue Type: Bug
> Components: Format
> Reporter: Wes McKinney
> Assignee: Wes McKinney
> Priority: Major
> Fix For: 0.1.0
>
>
> As brought up by Dan Robinson on the mailing list (thank you for catching
> this!), there is an inconsistency in the format documents in the
> representation of nulls with the ValueVectors code import -- since I drafted
> these format documents initially I'll take the blame for the inconsistency,
> but:
> * Drill / ValueVectors uses the value 0 for null data, and 1 for non-null data
> * The format document currently states the opposite (values are null if the
> bit is set)
> I can see arguments both ways, but one argument for the ValueVectors style is
> that values must be explicitly set to be non-null, versus uninitialized
> values being accidentally interpreted as being non-null. When initializing a
> bitmap, one can {{memset}} the bits to 0, then set then to 1 when non-null
> values are appended during construction.
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