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https://issues.apache.org/jira/browse/ACCUMULO-3602?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14485430#comment-14485430
]
ASF GitHub Bot commented on ACCUMULO-3602:
------------------------------------------
Github user echeipesh commented on a diff in the pull request:
https://github.com/apache/accumulo/pull/25#discussion_r27983742
--- Diff:
core/src/main/java/org/apache/accumulo/core/client/mapred/AbstractInputFormat.java
---
@@ -384,7 +387,21 @@ public static InputTableConfig
getInputTableConfig(JobConf job, String tableName
protected abstract static class AbstractRecordReader<K,V> implements
RecordReader<K,V> {
protected long numKeysRead;
protected Iterator<Map.Entry<Key,Value>> scannerIterator;
- protected RangeInputSplit split;
+ protected
org.apache.accumulo.core.client.mapreduce.impl.AccumuloInputSplit split;
+ protected ScannerBase scannerBase;
+
+ /**
+ * Configures the iterators on a scanner for the given table name.
+ *
+ * @param job
+ * the Hadoop job configuration
+ * @param scanner
+ * the scanner for which to configure the iterators
+ * @param tableName
+ * the table name for which the scanner is configured
+ * @since 1.7.0
+ */
+ protected abstract void setupIterators(JobConf job, ScannerBase
scanner, String tableName, AccumuloInputSplit split);
--- End diff --
That's a good point. In an effort to avoid mistakes of the past and keep
AccumulInputSplit out of public API how about something like this:
```java
// InputFormatBase
List<IteratorSetting> contextIterators(TaskAttemptContext context, String
tableName) {
return getIterators(context).getIterators();
}
// AccumululoMultiTableInputFormat
List<IteratorSetting> contextIterators(TaskAttemptContext context, String
tableName) {
return getInputTableConfig(context, tableName).getIterators();
}
// lift setupIterators to AbstractInputFormat (no longer abstract)
protected abstract List<IteratorSetting>
contextIterators(TaskAttemptContext context, String tableName);
private void setupIterators(TaskAttemptContext context, ScannerBase
scanner, String tableName, AccumuloInputSplit split) {
List<IteratorSetting> iterators = null;
if (null == split) {
iterators = contextIterators(context);
} else {
iterators = split.getIterators();
if (null == iterators) {
iterators = contextIterators(context);
}
}
for (IteratorSetting iterator : iterators)
scanner.addScanIterator(iterator);
}
```
Looking at code right now the only part that diverges is pulling out
default split if they're somehow unavailable in the split. This narrows the
interface, hopefully in an acceptable way?
> 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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