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https://issues.apache.org/jira/browse/HIVE-16274?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15942188#comment-15942188
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Lefty Leverenz commented on HIVE-16274:
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Doc note: This adds *hive.metastore.stats.ndv.tuner* to HiveConf.java, so it
needs to be documented in the wiki for release 2.3.0.
It belongs in the MetaStore section of Configuration Properties, with a
crossreference at the beginning of Statistics section. Or perhaps vice versa
(since MetaStore already has a list of parameters in other sections).
* [Configuration Properties -- MetaStore |
https://cwiki.apache.org/confluence/display/Hive/Configuration+Properties#ConfigurationProperties-MetaStore]
* [Configuration Properties -- Statistics |
https://cwiki.apache.org/confluence/display/Hive/Configuration+Properties#ConfigurationProperties-Statistics]
Added a TODOC2.3 label.
> Support tuning of NDV of columns using lower/upper bounds
> ---------------------------------------------------------
>
> Key: HIVE-16274
> URL: https://issues.apache.org/jira/browse/HIVE-16274
> Project: Hive
> Issue Type: Bug
> Affects Versions: 2.1.0
> Reporter: Pengcheng Xiong
> Assignee: Pengcheng Xiong
> Labels: TODOC2.3
> Fix For: 2.3.0
>
> Attachments: HIVE-16274.01.patch, HIVE-16274.02.patch
>
>
> For partitioned tables, the distinct value (nDV) estimate for a column is by
> default set to the largest nDV value in any of the partitions being
> considered, which is a lower bound on the nDV estimate.
> This provides a config setting to allow the estimate to a specified fraction
> (0.0 - 1.0) of the higher bound on the nDV estimate (the sum of all the nDVs
> in all partitions).
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