BELUGA BEHR commented on HIVE-16758:

[~csun] I created two patches.  One has a default replication of 10 and the 
other or 1.  Now that I look at it again, we should probably stick with the 
value of 10 since this will match the default setting of 
{{mapreduce.client.submit.file.replication}} in mapred-default.xml.

I guess the issue is that we're overloading the meaning of this configuration.  
One might be surprised to discover that it is being used in this manner, but 
the two use cases are very similar, therefore it's probably better to extend 
the use of this configuration than to introduce yet another configuration.  
That's my two cents.

> 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
>            Assignee: BELUGA BEHR
>            Priority: Minor
>         Attachments: HIVE-16758.1.patch, HIVE-16758.2.patch, 
> HIVE-16758.3.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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