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https://issues.apache.org/jira/browse/HIVE-16758?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16037179#comment-16037179
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BELUGA BEHR commented on HIVE-16758:
------------------------------------
Patch:
# Set the default number of replications to 1 to support single-node test
clusters
# Determine the number of replications based on
{{mapreduce.client.submit.file.replication}} instead of DFS replication max
# Removed logic which increased the Hash Table Sink file replication to be
based on the target directory's default replication instead of the configured
amount. This is confusing because it overrides a user setting without
explaining to the user why their configuration has been changed. Additionally,
this replication is about making the data locality reasonable for Executor
tasks and not about protecting data. The default replication value has a very
different goal than this replication value and therefore should not be linked.
> Better Select Number of Replications
> ------------------------------------
>
> Key: HIVE-16758
> URL: https://issues.apache.org/jira/browse/HIVE-16758
> Project: Hive
> Issue Type: Improvement
> Reporter: BELUGA BEHR
> Priority: Minor
> Attachments: HIVE-16758.1.patch
>
>
> {{org.apache.hadoop.hive.ql.exec.SparkHashTableSinkOperator.java}}
> We should be smarter about how we pick a replication number. We should add a
> new configuration equivalent to {{mapreduce.client.submit.file.replication}}.
> This value should be around the square root of the number of nodes and not
> hard-coded in the code.
> {code}
> public static final String DFS_REPLICATION_MAX = "dfs.replication.max";
> private int minReplication = 10;
> @Override
> protected void initializeOp(Configuration hconf) throws HiveException {
> ...
> int dfsMaxReplication = hconf.getInt(DFS_REPLICATION_MAX, minReplication);
> // minReplication value should not cross the value of dfs.replication.max
> minReplication = Math.min(minReplication, dfsMaxReplication);
> }
> {code}
> https://hadoop.apache.org/docs/r2.7.2/hadoop-mapreduce-client/hadoop-mapreduce-client-core/mapred-default.xml
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