George Smith created HIVE-17146:
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Summary: 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
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 causes 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 cluster:
{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.
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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