[
https://issues.apache.org/jira/browse/HIVE-16274?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
Jason Dere updated HIVE-16274:
------------------------------
Description:
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).
> 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
> Reporter: Pengcheng Xiong
> Assignee: Pengcheng Xiong
> Attachments: HIVE-16274.01.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).
--
This message was sent by Atlassian JIRA
(v6.3.15#6346)
