[jira] [Closed] (HIVE-15065) SimpleFetchOptimizer should decide based on metastore stats when available

["Owen O'Malley (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/HIVE-15065?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Owen O'Malley closed HIVE-15065.
--------------------------------

> SimpleFetchOptimizer should decide based on metastore stats when available
> --------------------------------------------------------------------------
>
>                 Key: HIVE-15065
>                 URL: https://issues.apache.org/jira/browse/HIVE-15065
>             Project: Hive
>          Issue Type: Bug
>          Components: Logical Optimizer
>    Affects Versions: 2.2.0
>            Reporter: Prasanth Jayachandran
>            Assignee: Prasanth Jayachandran
>             Fix For: 2.2.0
>
>         Attachments: HIVE-15065.1.patch
>
>
> Currently the decision to use fetch optimizer or not is based on scanning the filesystem for file lengths and see if the aggregated size is less the fetch task threshold. This can be very expensive for cloud environment. This issue is mitigated to some extent by HIVE-14920 but still that requires file system scan. We can make decision based on the stats from metastore and falling back when stats is not available. Since fast stats (numRows and fileSize) is always available this should work most of the time. 



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