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From "ASF GitHub Bot (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (ACCUMULO-3602) BatchScanner optimization for AccumuloInputFormat
Date Thu, 02 Apr 2015 02:56:53 GMT

    [ https://issues.apache.org/jira/browse/ACCUMULO-3602?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14392042#comment-14392042
] 

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

Github user joshelser commented on a diff in the pull request:

    https://github.com/apache/accumulo/pull/25#discussion_r27629761
  
    --- Diff: core/src/main/java/org/apache/accumulo/core/client/mapreduce/RangeInputSplit.java
---
    @@ -179,81 +93,13 @@ public void readFields(DataInput in) throws IOException {
         if (in.readBoolean()) {
           localIterators = in.readBoolean();
         }
    -
    -    if (in.readBoolean()) {
    -      mockInstance = in.readBoolean();
    -    }
    -
    -    if (in.readBoolean()) {
    -      int numColumns = in.readInt();
    -      List<String> columns = new ArrayList<String>(numColumns);
    -      for (int i = 0; i < numColumns; i++) {
    -        columns.add(in.readUTF());
    -      }
    -
    -      fetchedColumns = InputConfigurator.deserializeFetchedColumns(columns);
    -    }
    -
    -    if (in.readBoolean()) {
    -      String strAuths = in.readUTF();
    -      auths = new Authorizations(strAuths.getBytes(UTF_8));
    -    }
    -
    -    if (in.readBoolean()) {
    -      principal = in.readUTF();
    -    }
    -
    -    if (in.readBoolean()) {
    -      int ordinal = in.readInt();
    -      this.tokenSource = TokenSource.values()[ordinal];
    -
    -      switch (this.tokenSource) {
    -        case INLINE:
    -          String tokenClass = in.readUTF();
    -          byte[] base64TokenBytes = in.readUTF().getBytes(UTF_8);
    -          byte[] tokenBytes = Base64.decodeBase64(base64TokenBytes);
    -
    -          this.token = AuthenticationTokenSerializer.deserialize(tokenClass, tokenBytes);
    -          break;
    -
    -        case FILE:
    -          this.tokenFile = in.readUTF();
    -
    -          break;
    -        default:
    -          throw new IOException("Cannot parse unknown TokenSource ordinal");
    -      }
    -    }
    -
    -    if (in.readBoolean()) {
    -      instanceName = in.readUTF();
    -    }
    -
    -    if (in.readBoolean()) {
    -      zooKeepers = in.readUTF();
    -    }
    -
    -    if (in.readBoolean()) {
    -      int numIterators = in.readInt();
    -      iterators = new ArrayList<IteratorSetting>(numIterators);
    -      for (int i = 0; i < numIterators; i++) {
    -        iterators.add(new IteratorSetting(in));
    -      }
    -    }
    -
    -    if (in.readBoolean()) {
    -      level = Level.toLevel(in.readInt());
    -    }
       }
     
       @Override
       public void write(DataOutput out) throws IOException {
    --- End diff --
    
    Need to serialize offline here.


> 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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