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https://issues.apache.org/jira/browse/HIVE-18622?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16367499#comment-16367499
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Matt McCline commented on HIVE-18622:
-------------------------------------
Thank you [~sershe], [~djaiswal] [~vihangk1] [~gopalv] for your review and help.
> Vectorization: IF Statements, Comparisons, and more do not handle NULLs
> correctly
> ---------------------------------------------------------------------------------
>
> Key: HIVE-18622
> URL: https://issues.apache.org/jira/browse/HIVE-18622
> Project: Hive
> Issue Type: Bug
> Components: Hive
> Reporter: Matt McCline
> Assignee: Matt McCline
> Priority: Critical
> Fix For: 3.0.0
>
> Attachments: HIVE-18622.03.patch, HIVE-18622.04.patch,
> HIVE-18622.05.patch, HIVE-18622.06.patch, HIVE-18622.07.patch,
> HIVE-18622.08.patch, HIVE-18622.09.patch, HIVE-18622.091.patch,
> HIVE-18622.092.patch, HIVE-18622.093.patch, HIVE-18622.094.patch,
> HIVE-18622.095.patch, HIVE-18622.096.patch, HIVE-18622.097.patch,
> HIVE-18622.098.patch, HIVE-18622.099.patch, HIVE-18622.0992.patch,
> HIVE-18622.0993.patch, HIVE-18622.0994.patch
>
>
>
> Many vector expression classes are setting noNulls to true which does not
> work if the VRB is a scratch column being reused. The previous use may have
> set noNulls to false and the isNull array will have some rows marked as NULL.
> The result is wrong query results and sometimes NPEs (for BytesColumnVector).
> So, many vector expressions need this:
> {code:java}
> // Carefully handle NULLs...
> /*
> * For better performance on LONG/DOUBLE we don't want the conditional
> * statements inside the for loop.
> */
> outputColVector.noNulls = false;
> {code}
> And, vector expressions need to make sure the isNull array entry is set when
> outputColVector.noNulls is false.
> And, all place that assign column value need to set noNulls to false when the
> value is NULL.
> Almost all cases where noNulls is set to true are incorrect.
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