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https://issues.apache.org/jira/browse/HIVE-17146?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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George Smith updated HIVE-17146:
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Attachment: dfs.replication-settings.png
Our current Cloudera- hdfs settings
> Spark on Hive - Exception while joining tables - "Requested replication
> factor of 10 exceeds maximum of x"
> -----------------------------------------------------------------------------------------------------------
>
> Key: HIVE-17146
> URL: https://issues.apache.org/jira/browse/HIVE-17146
> Project: Hive
> Issue Type: Bug
> Components: Hive
> Affects Versions: 2.1.1, 3.0.0
> Reporter: George Smith
> Assignee: Ashutosh Chauhan
> Attachments: dfs.replication-settings.png
>
>
> We found a bug in the current implementation of
> [org.apache.hadoop.hive.ql.exec.SparkHashTableSinkOperator|https://github.com/apache/hive/blob/master/ql/src/java/org/apache/hadoop/hive/ql/exec/SparkHashTableSinkOperator.java]
> The *magic number 10* for minReplication factor can cause the exception when
> the configuration parameter _dfs.replication_ is lower than 10.
> Consider these [properties
> configuration|https://hadoop.apache.org/docs/r2.7.2/hadoop-project-dist/hadoop-hdfs/hdfs-default.xml]
> on our cluster (with less than 10 nodes):
> {code}
> dfs.namenode.replication.min=1
> dfs.replication=2
> dfs.replication.max=512 (that's the default value)
> {code}
> The current implementation counts target file replication as follows
> (relevant snippets of the code):
> {code}
> private int minReplication = 10;
> ...
> int dfsMaxReplication = hconf.getInt(DFS_REPLICATION_MAX, minReplication);
> // minReplication value should not cross the value of dfs.replication.max
> minReplication = Math.min(minReplication, dfsMaxReplication);
> ...
> FileSystem fs = path.getFileSystem(htsOperator.getConfiguration());
> short replication = fs.getDefaultReplication(path);
> ...
> int numOfPartitions = replication;
> replication = (short) Math.max(minReplication, numOfPartitions);
> //use replication value in fs.create(path, replication);
> {code}
> With a current code the used replication value is 10 and the config value
> _dfs.replication_ is not used at all.
> There are probably more (easy) ways to fix it:
> # Set field {code}private int minReplication = 1 ; {code} I don't see any
> obvious reason for the value 10. or
> # Init minReplication from config value _dfs.namenode.replication.min_ with a
> default value 1. or
> # Count replication this way: {code}replication = Math.min(numOfPartitions,
> dfsMaxReplication);{code} or
> # Use replication = numOfPartitions; directly
> Config value _dfs.replication_ has a default value 3 which is supposed to be
> always lower than "dfs.replication.max", no checking is probably needed.
> Any suggestions which option to choose?
> As a *workaround* for this issue we had to set dfs.replication.max=2, but
> obviously _dfs.replication_ value should NOT be ignored and the problem
> should be resolved.
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