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https://issues.apache.org/jira/browse/PARQUET-2244?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17689557#comment-17689557
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ASF GitHub Bot commented on PARQUET-2244:
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zhongyujiang commented on PR #1028:
URL: https://github.com/apache/parquet-mr/pull/1028#issuecomment-1432596607
Didn't think about comparisons with non-null values before submitting this
PR. I don't know if there is a downstream that relies on Parquet judge `value
<> null` as TRUE instead of UNKNOW, I guess that might be in some non-ansi
standard engines. If there is no such situation, I think this PR can be
reverted safely.
> Dictionary filter may skip row-groups incorrectly when evaluating notIn
> -----------------------------------------------------------------------
>
> Key: PARQUET-2244
> URL: https://issues.apache.org/jira/browse/PARQUET-2244
> Project: Parquet
> Issue Type: Bug
> Components: parquet-mr
> Affects Versions: 1.12.2
> Reporter: Yujiang Zhong
> Assignee: Yujiang Zhong
> Priority: Major
>
> Dictionary filter may skip row-groups incorrectly when evaluating `notIn` on
> optional columns with null values. Here is an example:
> Say there is a optional column `c1` with all pages dict encoded, `c1` has and
> only has two distinct values: ['foo', null], and the predicate is `c1 not
> in ('foo', 'bar')`.
> Now dictionary filter may skip this row-group that is actually should not be
> skipped, because there are nulls in the column.
>
> This is a bug similar to #1510.
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