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https://issues.apache.org/jira/browse/DRILL-5098?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15951773#comment-15951773
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Bridget Bevens commented on DRILL-5098:
---------------------------------------

Link to 
doc:http://drill.apache.org/docs/using-the-jdbc-driver/#using-the-jdbc-url-format-for-a-direct-drillbit-connection

> Improving fault tolerance for connection between client and foreman node.
> -------------------------------------------------------------------------
>
>                 Key: DRILL-5098
>                 URL: https://issues.apache.org/jira/browse/DRILL-5098
>             Project: Apache Drill
>          Issue Type: Improvement
>          Components: Client - JDBC
>            Reporter: Sorabh Hamirwasia
>            Assignee: Sorabh Hamirwasia
>              Labels: doc-impacting, ready-to-commit
>             Fix For: 1.10.0
>
>
> With DRILL-5015 we allowed support for specifying multiple Drillbits in 
> connection string and randomly choosing one out of it. Over time some of the 
> Drillbits specified in the connection string may die and the client can fail 
> to connect to Foreman node if random selection happens to be of dead Drillbit.
> Even if ZooKeeper is used for selecting a random Drillbit from the registered 
> one there is a small window when client selects one Drillbit and then that 
> Drillbit went down. The client will fail to connect to this Drillbit and 
> error out. 
> Instead if we try multiple Drillbits (configurable tries count through 
> connection string) then the probability of hitting this error window will 
> reduce in both the cases improving fault tolerance. During further 
> investigation it was also found that if there is Authentication failure then 
> we throw that error as generic RpcException. We need to improve that as well 
> to capture this case explicitly since in case of Auth failure we don't want 
> to try multiple Drillbits.
> Connection string example with new parameter:
> jdbc:drill:drillbit=<node name>[:<port>][,<node name2>[:<port>]...;tries=5



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