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From "Anja Gruenheid (JIRA)" <j...@apache.org>
Subject [jira] Commented: (HIVE-1940) Query Optimization Using Column Metadata and Histograms
Date Tue, 15 Feb 2011 20:33:57 GMT

    [ https://issues.apache.org/jira/browse/HIVE-1940?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12994987#comment-12994987
] 

Anja Gruenheid commented on HIVE-1940:
--------------------------------------

I tried figuring out datanucleus and the creation of the initial metastore model, but I don't
quite understand it:

When I create the metastore in MySQL, I generate the jars by running ant model-jar in the
hive/metastore folder. When I then run hive, metastore tables are generated according the
command that I use (eg show tables) in MySQL. I referenced org.datanucleus.store.rdbms.SchemaTool
instead of jpox before generating the jar file, but it didn't change anything. Basically,
there has to be an overview of all metastore tables that can possibly be invoked. My question
is: where?

Thanks a lot for your help!

> Query Optimization Using Column Metadata and Histograms
> -------------------------------------------------------
>
>                 Key: HIVE-1940
>                 URL: https://issues.apache.org/jira/browse/HIVE-1940
>             Project: Hive
>          Issue Type: New Feature
>          Components: Metastore, Query Processor
>            Reporter: Anja Gruenheid
>         Attachments: HiveMetaStore.pdf
>
>
> The current basis for cost-based query optimization in Hive is information gathered on
tables and partitions. To make further improvements in query optimization possible, the next
step is to develop and implement possibilities to gather information on columns as discussed
in issue HIVE-33. After that, an implementation of histograms is a possible option to use
and collect run-time statistics. Next to the actual implementation of these features, it is
also necessary to develop a consistent storage model for the MetaStore.

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