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https://issues.apache.org/jira/browse/ACCUMULO-3602?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14392041#comment-14392041
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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_r27629755
--- Diff:
core/src/main/java/org/apache/accumulo/core/client/mapreduce/RangeInputSplit.java
---
@@ -135,38 +72,15 @@ public float getProgress(Key currentKey) {
*/
@Override
public long getLength() throws IOException {
- Text startRow = range.isInfiniteStartKey() ? new Text(new byte[]
{Byte.MIN_VALUE}) : range.getStartKey().getRow();
- Text stopRow = range.isInfiniteStopKey() ? new Text(new byte[]
{Byte.MAX_VALUE}) : range.getEndKey().getRow();
- int maxCommon = Math.min(7, Math.min(startRow.getLength(),
stopRow.getLength()));
- long diff = 0;
-
- byte[] start = startRow.getBytes();
- byte[] stop = stopRow.getBytes();
- for (int i = 0; i < maxCommon; ++i) {
- diff |= 0xff & (start[i] ^ stop[i]);
- diff <<= Byte.SIZE;
- }
-
- if (startRow.getLength() != stopRow.getLength())
- diff |= 0xff;
-
- return diff + 1;
+ return getRangeLength(range);
}
- @Override
- public String[] getLocations() throws IOException {
- return Arrays.copyOf(locations, locations.length);
- }
@Override
public void readFields(DataInput in) throws IOException {
--- End diff --
Need to get offline from the serialization.
> 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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