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From "pengcheng xiong (JIRA)" <j...@apache.org>
Subject [jira] [Created] (HIVE-7654) A method to extrapolate columnStats for partitions of a table
Date Thu, 07 Aug 2014 21:53:13 GMT
pengcheng xiong created HIVE-7654:
-------------------------------------

             Summary: A method to extrapolate columnStats for partitions of a table
                 Key: HIVE-7654
                 URL: https://issues.apache.org/jira/browse/HIVE-7654
             Project: Hive
          Issue Type: New Feature
            Reporter: pengcheng xiong
            Assignee: pengcheng xiong
            Priority: Minor
         Attachments: Extrapolate the Column Status.docx

In a PARTITIONED table, there are many partitions. For example, 

create table if not exists loc_orc (
  state string,
  locid int,
  zip bigint
) partitioned by(year string) stored as orc;

We assume there are 4 partitions, partition(year='2000'), partition(year='2001'), partition(year='2002')
and partition(year='2003').

We can use the following command to compute statistics for columns state,locid of partition(year='2001')

analyze table loc_orc partition(year='2001') compute statistics for columns state,locid;

We need to know the “aggregated” column status for the whole table loc_orc. However, we
may not have the column status for some partitions, e.g., partition(year='2002') and also
we may not have the column status for some columns, e.g., zip bigint for partition(year='2001')

We propose a method to extrapolate the missing column status for the partitions.




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