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https://issues.apache.org/jira/browse/ACCUMULO-3602?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14500103#comment-14500103
]
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_r28607317
--- 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) {
+ // group ranges by tablet to be read by a BatchScanner
+ ArrayList<Range> clippedRanges = new ArrayList<Range>();
+ for(Range r: extentRanges.getValue())
--- End diff --
Sorry for confusing you guys, it's actually backwards. BatchScan does
essentially the same thing as AutoAdjust in terms of clipping on tablet
boundaries. AutoAdjust is on by default, so there is no issue. Asking for
BatchScan and AutoAdjust off is a nonsensical case.
So I've added mentions in both javadocs as Keith suggested and an exception
on AutoAdjust = false BatchScan = true, since it indicates user specifically
asked for something we can not and know not how to give them.
This is pushed up now.
> 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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