Wes McKinney created ARROW-62:
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Summary: 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
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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