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https://issues.apache.org/jira/browse/HIVE-15987?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Teddy Choi reassigned HIVE-15987:
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Assignee: (was: Teddy Choi)
> Replace ColumnVector.isNull boolean[] impl. with BitSet
> -------------------------------------------------------
>
> Key: HIVE-15987
> URL: https://issues.apache.org/jira/browse/HIVE-15987
> Project: Hive
> Issue Type: Improvement
> Components: Vectorization
> Reporter: Teddy Choi
> Labels: incompatibleChange
>
> Most of data operations in Hive uses null operations. The current
> implementation of ColumnVector.isNull uses a boolean array, which uses 8 bits
> per 1 boolean. BitSet is a more compact representation, as it uses 1 bit per
> 1 boolean with a backing long array. Also logical operations between longs
> are much faster than ones with bytes as it uses less instructions per byte.
> So it will bring 8x or more performance for null operations.
> However, there also are several cases that will make this improvement slow.
> Such as simple reads will require more instructions per row. So it should
> include benchmark tests to show its performance impact.
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