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https://issues.apache.org/jira/browse/ACCUMULO-3602?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14484025#comment-14484025
]
ASF GitHub Bot commented on ACCUMULO-3602:
------------------------------------------
Github user keith-turner commented on a diff in the pull request:
https://github.com/apache/accumulo/pull/25#discussion_r27918917
--- Diff:
core/src/main/java/org/apache/accumulo/core/client/mapred/AbstractInputFormat.java
---
@@ -629,32 +676,37 @@ public float getProgress() throws IOException {
}
for (Map.Entry<KeyExtent,List<Range>> extentRanges :
tserverBin.getValue().entrySet()) {
Range ke = extentRanges.getKey().toDataRange();
- for (Range r : extentRanges.getValue()) {
- if (autoAdjust) {
- // divide ranges into smaller ranges, based on the tablets
- RangeInputSplit split = new RangeInputSplit(tableName,
tableId, ke.clip(r), new String[] {location});
-
- split.setOffline(tableConfig.isOfflineScan());
-
split.setIsolatedScan(tableConfig.shouldUseIsolatedScanners());
-
split.setUsesLocalIterators(tableConfig.shouldUseLocalIterators());
- split.setMockInstance(mockInstance);
- split.setFetchedColumns(tableConfig.getFetchedColumns());
- split.setPrincipal(principal);
- split.setToken(token);
- split.setInstanceName(instance.getInstanceName());
- split.setZooKeepers(instance.getZooKeepers());
- split.setAuths(auths);
- split.setIterators(tableConfig.getIterators());
- split.setLogLevel(logLevel);
-
- splits.add(split);
- } else {
- // don't divide ranges
- ArrayList<String> locations = splitsToAdd.get(r);
- if (locations == null)
- locations = new ArrayList<String>(1);
- locations.add(location);
- splitsToAdd.put(r, locations);
+ if (batchScan && supportBatchScan) {
--- End diff --
> Mostly for code clarity
It threw me a bit, made me wonder if there was a code path I was missing.
> 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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