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Date: Fri, 27 Mar 2015 15:10:54 +0000 (UTC)
From: "Josh Elser (JIRA)" <jira@apache.org>
To: notifications@accumulo.apache.org
Message-ID: <JIRA.12776000.1424296315000.50541.1427469054109@Atlassian.JIRA>
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Subject: [jira] [Commented] (ACCUMULO-3602) BatchScanner optimization for
 AccumuloInputFormat
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    [ https://issues.apache.org/jira/browse/ACCUMULO-3602?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14383975#comment-14383975 ] 

Josh Elser commented on ACCUMULO-3602:
--------------------------------------

bq. Thank you for the review, I've made those adjustments.

So this is ready for another review (and potential commit)? If so, please rebase your branch on top of master (This branch is 4 commits ahead, 1675 commits behind apache:master) and either open up a pull request or submit a patch here. Thanks!

> BatchScanner optimization for AccumuloInputFormat
> -------------------------------------------------
>
>                 Key: ACCUMULO-3602
>                 URL: https://issues.apache.org/jira/browse/ACCUMULO-3602
>             Project: Accumulo
>          Issue Type: Improvement
>          Components: client
>    Affects Versions: 1.6.1, 1.6.2
>            Reporter: Eugene Cheipesh
>            Assignee: Eugene Cheipesh
>              Labels: performance
>
> Currently {{AccumuloInputFormat}} produces a split for reach {{Range}} specified in the configuration. Some table indexing schemes, for instance z-order geospacial index, produce large number of small ranges resulting in large number of splits. This is specifically a concern when using {{AccumuloInputFormat}} as a source for Spark RDD where each Split is mapped to an RDD partition.
> Large number of small RDD partitions leads to poor parallism on read and high overhead on processing. A desirable alternative is to group ranges by tablet into a single split and use {{BatchScanner}} to produce the records. Grouping by tablets is useful because it represents Accumulos attempt to distributed stored records and can be influance by the user through table splits.
> The grouping functionality already exists in the internal {{TabletLocator}} class. 
> Current proposal is to modify {{AbstractInputFormat}} such that it generates either {{RangeInputSplit}} or {{MultiRangeInputSplit}} based on a new setting in {{InputConfigurator}}.  {{AccumuloInputFormat}} would then be able to inspect the type of the split and instantiate an appropriate reader.
> The functinality of {{TabletLocator}} should be exposed as a public API in 1.7 as it is useful for optimizations.


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