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Date: Mon, 7 Feb 2011 19:41:57 +0000 (UTC)
From: "John Sichi (JIRA)" <jira@apache.org>
To: hive-dev@hadoop.apache.org
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Subject: [jira] Commented: (HIVE-1940) Query Optimization Using Column
 Metadata and Histograms
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    [ https://issues.apache.org/jira/browse/HIVE-1940?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12991542#comment-12991542 ] 

John Sichi commented on HIVE-1940:
----------------------------------

Awesome diagram!  Can you add it as an attachment and check the radio button to grant license to ASF so that we can use it in the Hive wiki?

Try loading some data into your partitions; maybe it deferred that part of the schema creation until then.

There's a tool which can force generation of the entire schema:

http://www.datanucleus.org/products/accessplatform/rdbms/schematool.html

There's an ant target generate-schema which invokes it (in metastore/build.xml), but it's out-of-date because it still references jpox instead of datanucleus (e.g. it should be invoking org.datanucleus.store.rdbms.SchemaTool instead of org.jpox.SchemaTool).  If you get it working, submit a patch and we can update it.


> 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
>
> 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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