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Date: Wed, 24 Jul 2013 20:23:48 +0000 (UTC)
From: "Laljo John Pullokkaran (JIRA)" <jira@apache.org>
To: hive-dev@hadoop.apache.org
Message-ID: <JIRA.12658387.1374096980468.106324.1374697428746@arcas>
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Subject: [jira] [Commented] (HIVE-4878) With Dynamic partitioning, some
 queries would scan default partition even if query is not using it.
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    [ https://issues.apache.org/jira/browse/HIVE-4878?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13718788#comment-13718788 ] 

Laljo John Pullokkaran commented on HIVE-4878:
----------------------------------------------

Resubmitted the patch to do partition skip regardless of "Dynamic Partition Mode". 

This fix avoids scanning default partition if all of the following is true:
a) partition pruning expression failed to evaluate for a given partition.
b) at the least one of the columns in the partition is default partition.
                
> With Dynamic partitioning, some queries would scan default partition even if query is not using it.
> ---------------------------------------------------------------------------------------------------
>
>                 Key: HIVE-4878
>                 URL: https://issues.apache.org/jira/browse/HIVE-4878
>             Project: Hive
>          Issue Type: Bug
>          Components: Query Processor
>    Affects Versions: 0.11.0
>            Reporter: Laljo John Pullokkaran
>            Assignee: Laljo John Pullokkaran
>             Fix For: 0.11.1
>
>         Attachments: HIVE-4878.patch
>
>
> With Dynamic partitioning, Hive would scan default partitions in some cases even if query excludes it.
> As part of partition pruning, predicate is narrowed down to those pieces that involve partition columns only. This predicate is then evaluated with partition values to determine, if scan should include those partitions.
> But in some cases (like when comparing "__HIVE_DEFAULT_PARTITION__" to numeric data types) expression evaluation would fail and would return NULL instead of true/false. In such cases the partition is added to unknown partitions which is then subsequently scanned.

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