Mailing-List: contact pig-dev-help@hadoop.apache.org; run by ezmlm
Precedence: bulk
Reply-To: pig-dev@hadoop.apache.org
Message-ID: <1392912799.1257928119751.JavaMail.jira@brutus>
Date: Wed, 11 Nov 2009 08:28:39 +0000 (UTC)
From: "Daniel Dai (JIRA)" <jira@apache.org>
To: pig-dev@hadoop.apache.org
Subject: [jira] Updated: (PIG-1038) Optimize nested distinct/sort to use
 secondary key
In-Reply-To: <176669728.1256162219484.JavaMail.jira@brutus>
MIME-Version: 1.0
Content-Type: text/plain; charset=utf-8
Content-Transfer-Encoding: 7bit


     [ https://issues.apache.org/jira/browse/PIG-1038?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Daniel Dai updated PIG-1038:
----------------------------

    Status: Patch Available  (was: Open)

> Optimize nested distinct/sort to use secondary key
> --------------------------------------------------
>
>                 Key: PIG-1038
>                 URL: https://issues.apache.org/jira/browse/PIG-1038
>             Project: Pig
>          Issue Type: Improvement
>          Components: impl
>    Affects Versions: 0.4.0
>            Reporter: Olga Natkovich
>            Assignee: Daniel Dai
>             Fix For: 0.6.0
>
>         Attachments: PIG-1038-1.patch, PIG-1038-2.patch, PIG-1038-3.patch
>
>
> If nested foreach plan contains sort/distinct, it is possible to use hadoop secondary sort instead of SortedDataBag and DistinctDataBag to optimize the query. 
> Eg1:
> A = load 'mydata';
> B = group A by $0;
> C = foreach B {
>     D = order A by $1;
>     generate group, D;
> }
> store C into 'myresult';
> We can specify a secondary sort on A.$1, and drop "order A by $1".
> Eg2:
> A = load 'mydata';
> B = group A by $0;
> C = foreach B {
>     D = A.$1;
>     E = distinct D;
>     generate group, E;
> }
> store C into 'myresult';
> We can specify a secondary sort key on A.$1, and simplify "D=A.$1; E=distinct D" to a special version of distinct, which does not do the sorting.

-- 
This message is automatically generated by JIRA.
-
You can reply to this email to add a comment to the issue online.