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Date: Wed, 1 Apr 2015 19:04:54 +0000 (UTC)
From: "ASF GitHub Bot (JIRA)" <jira@apache.org>
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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=14391246#comment-14391246 ] 

ASF GitHub Bot commented on ACCUMULO-3602:
------------------------------------------

Github user joshelser commented on the pull request:

    https://github.com/apache/accumulo/pull/25#issuecomment-88596530
  
    Ack, I'm sorry, @echeipesh, I just broke you. `RangeInputSplit.getInstance()` is nonsensical. It should use the ClientConfiguration from the Job's configuration (which can only be gotten by the RecordReader using the TaskAttemptContext). LMK if that doesn't make sense and I can send you a patch to fix your branch.


> 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
>             Fix For: 1.7.0
>
>
> 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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