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From "Prasanth Jayachandran (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (HIVE-15129) LLAP : Enhance cache hits for stripe metadata across queries
Date Wed, 16 Nov 2016 06:45:59 GMT

     [ https://issues.apache.org/jira/browse/HIVE-15129?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Prasanth Jayachandran updated HIVE-15129:
-----------------------------------------
    Assignee: Rajesh Balamohan

> LLAP : Enhance cache hits for stripe metadata across queries
> ------------------------------------------------------------
>
>                 Key: HIVE-15129
>                 URL: https://issues.apache.org/jira/browse/HIVE-15129
>             Project: Hive
>          Issue Type: Improvement
>          Components: llap
>    Affects Versions: 2.2.0
>            Reporter: Rajesh Balamohan
>            Assignee: Rajesh Balamohan
>            Priority: Minor
>             Fix For: 2.2.0
>
>         Attachments: HIVE-15129.1.patch, HIVE-15129.2.patch, HIVE-15129.3.patch
>
>
> When multiple queries are run in LLAP, stripe metadata cache misses were observed even
though enough memory was available. 
> https://github.com/apache/hive/blob/master/llap-server/src/java/org/apache/hadoop/hive/llap/io/encoded/OrcEncodedDataReader.java#L655.
Even in cases when data was found in cache, it wasn't getting used as {{globalnc}} changed
from query to query.  Creating a superset of existing indexes with {{globalInc}} would be
helpful. 
> This would be lot more beneficial in cloud storage where opening and reading small of
data can be expensive compared to HDFS. 



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