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https://issues.apache.org/jira/browse/CASSJAVA-92?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17945178#comment-17945178
 ] 

Bret McGuire commented on CASSJAVA-92:
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To [~smiklosovic] 's question 
[above|https://issues.apache.org/jira/browse/CASSJAVA-92?focusedCommentId=17944648&page=com.atlassian.jira.plugin.system.issuetabpanels%3Acomment-tabpanel#comment-17944648]
 re: what about other drivers... I haven't done an exhaustive check on all of 
them but I did do some digging on Python and gocql earlier today as (perhaps?) 
representative cases.  Each of them seem to include:


 * LBPs which make use of local DC information 
([Python|https://github.com/datastax/python-driver/blob/3.29.2/cassandra/policies.py#L201],
 
[gocql|[https://github.com/apache/cassandra-gocql-driver/blob/v1.7.0/policies.go#L834-L846])]
 * STARTUP message generation which is pretty isolated 
([Python|https://github.com/datastax/python-driver/blob/3.29.2/cassandra/connection.py#L1389-L1400],
 
[gocql|[https://github.com/apache/cassandra-gocql-driver/blob/v1.7.0/conn.go#L446-L483])]

 

In the gocql case DCAwareRoundRobinPolicy is [not the 
default|https://github.com/apache/cassandra-gocql-driver/blob/v1.7.0/session.go#L172-L174]
 but [can be 
configured|https://github.com/apache/cassandra-gocql-driver/blob/v1.7.0/doc.go#L115-L128]
 via the cluster's PoolConfig.

 

DCAwareRoundRobinPolicy [is either the default or the foundation for the 
default|https://github.com/datastax/python-driver/blob/3.29.2/cassandra/cluster.py#L261-L264]
 (depending on the availability of the murmur3 impl) for the Python driver.

> Add Local DC to driver connection info and provide visibility with nodetool 
> clientstats
> ---------------------------------------------------------------------------------------
>
>                 Key: CASSJAVA-92
>                 URL: https://issues.apache.org/jira/browse/CASSJAVA-92
>             Project: Apache Cassandra Java driver
>          Issue Type: Improvement
>          Components: Core
>            Reporter: Brad Schoening
>            Assignee: Lukasz Antoniak
>            Priority: Normal
>          Time Spent: 40m
>  Remaining Estimate: 0h
>
> When a client application connects to Cassandra using one of the drivers, it 
> specifies a local DC now. If the server is aware of the local DC specified, 
> this would be very useful to include in {_}nodetool clientstats{_}.
> We often have clusters running disaster recovery scenarios and they'll turn 
> off NTR on a DC. But they do not always understand what DC's are being used 
> as local DC if they have dozens of applications connecting from different 
> teams. In a brown-out scenario, this would also be useful to identify the 
> applications connecting to a degraded datacenter.



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