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https://issues.apache.org/jira/browse/HIVE-13089?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15154999#comment-15154999
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Prasanth Jayachandran commented on HIVE-13089:
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LGTM, +1. Pending tests.
> Rounding in Stats for equality expressions
> ------------------------------------------
>
> Key: HIVE-13089
> URL: https://issues.apache.org/jira/browse/HIVE-13089
> Project: Hive
> Issue Type: Bug
> Components: Statistics
> Affects Versions: 2.1.0
> Reporter: Jesus Camacho Rodriguez
> Assignee: Jesus Camacho Rodriguez
> Attachments: HIVE-13089.patch
>
>
> Currently we divide numRows(long) by countDistinct(long), thus ignoring the
> decimals. We should do proper rounding.
> This is specially useful for equality expressions over columns whose values
> are unique. As NDV estimates allow for a certain error, if countDistinct >
> numRows, we end up with 0 rows in the estimate for the expression.
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