[
https://issues.apache.org/jira/browse/HIVE-29438?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
Work on HIVE-29438 started by Konstantin Bereznyakov.
-----------------------------------------------------
> Statistics: inaccurate handling of unknown numNulls/numTrues/numFalses stats
> ----------------------------------------------------------------------------
>
> Key: HIVE-29438
> URL: https://issues.apache.org/jira/browse/HIVE-29438
> Project: Hive
> Issue Type: Bug
> Reporter: Konstantin Bereznyakov
> Assignee: Konstantin Bereznyakov
> Priority: Major
> Labels: pull-request-available
>
> In some implementations, it can be very expensive to maintain fully
> accurate column statistics, especially for large tables. The recommended
> value to use when numNulls/numFalses/numTrues are unknown is -1.
> However, the statistics code has a few places where it treats "-1" as a
> literal quantity rather than a sentinel value, leading to inaccurate and
> sometimes catastrophic estimations (e.g., incorrect join ordering, wrong
> memory allocation for operators).
--
This message was sent by Atlassian Jira
(v8.20.10#820010)
