hive-issues mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From "Laljo John Pullokkaran (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HIVE-9392) JoinStatsRule miscalculates join cardinality as incorrect NDV is used due to column names having duplicated fqColumnName
Date Fri, 22 May 2015 23:10:17 GMT

    [ https://issues.apache.org/jira/browse/HIVE-9392?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14556974#comment-14556974
] 

Laljo John Pullokkaran commented on HIVE-9392:
----------------------------------------------

[~pxiong] Please rebase the patch.

> JoinStatsRule miscalculates join cardinality as incorrect NDV is used due to column names
having duplicated fqColumnName
> ------------------------------------------------------------------------------------------------------------------------
>
>                 Key: HIVE-9392
>                 URL: https://issues.apache.org/jira/browse/HIVE-9392
>             Project: Hive
>          Issue Type: Bug
>          Components: Physical Optimizer
>    Affects Versions: 0.14.0
>            Reporter: Mostafa Mokhtar
>            Assignee: Pengcheng Xiong
>            Priority: Critical
>         Attachments: HIVE-9392.1.patch, HIVE-9392.2.patch, HIVE-9392.3.patch, HIVE-9392.4.patch,
HIVE-9392.5.patch, HIVE-9392.6.patch
>
>
> In JoinStatsRule.process the join column statistics are stored in HashMap  joinedColStats,
the key used which is the ColStatistics.fqColName is duplicated between join column in the
same vertex, as a result distinctVals ends up having duplicated values which negatively affects
the join cardinality estimation.
> The duplicate keys are usually named KEY.reducesinkkey0.



--
This message was sent by Atlassian JIRA
(v6.3.4#6332)

Mime
View raw message