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question).
--
Sylvain
On Thu, Jun 19, 2014 at 5:22 AM, Shaheen Afroz <shaheenn.af...@gmail.com>
wrote:
> +Cassandra DL
>
> We have Cassandra nodes in three datacenters - dc1, dc2 and dc3 and the
> cluster name is DataCluster. In the same way, our application code is also
> in same three datacenters. Our application code is accessing cassandra.
>
> Now I want to make sure if application call is coming from `dc1` then it
> should go to cassandra `dc1` always. Same with `dc2` and `dc3`.
>
> So I decided to use DCAwareRoundRobinPolicy of datastax java driver.
> Cassandra version we have is DSE 4.0 and datastax java driver version we
> are using is 2.0.2.
>
> But somehow with the below code it always gives me an excpetion as
> NoHostAvailableException -
>
> com.datastax.driver.core.exceptions.NoHostAvailableException: All host(s)
> tried for query failed (no host was tried)
> But in the same code, if I comment out below line and run it again. It
> works fine without any problem. That is pretty strange. What could be wrong
> with DCAwareRoundRobinPolicy or Cassandra setup?
>
> .withLoadBalancingPolicy(new DCAwareRoundRobinPolicy("dc1"))
> Below is my code -
>
> public static Cluster cluster;
> public static Session session;
> public static Builder builder;
>
> public static void main(String[] args) {
>
> try {
> builder = Cluster.builder();
> builder.addContactPoint("some1_dc1_machine");
> builder.addContactPoint("some2_dc1_machine");
> builder.addContactPoint("some1_dc2_machine");
> builder.addContactPoint("some2_dc2_machine");
> builder.addContactPoint("some1_dc3_machine");
> builder.addContactPoint("some2_dc3_machine");
> PoolingOptions opts = new PoolingOptions();
> opts.setCoreConnectionsPerHost(HostDistance.LOCAL,
> opts.getCoreConnectionsPerHost(HostDistance.LOCAL));
>
> SocketOptions socketOpts = new SocketOptions();
> socketOpts.setReceiveBufferSize(1048576);
> socketOpts.setSendBufferSize(1048576);
> socketOpts.setTcpNoDelay(false);
>
> cluster = builder
> .withSocketOptions(socketOpts)
> .withRetryPolicy(DowngradingConsistencyRetryPolicy.INSTANCE)
> .withPoolingOptions(opts)
> .withReconnectionPolicy(new ConstantReconnectionPolicy(100L))
> .withLoadBalancingPolicy(new DCAwareRoundRobinPolicy("dc1"))
> .withCredentials("username", "password")
> .build();
>
>
> session = cluster.connect("testingkeyspace");
> Metadata metadata = cluster.getMetadata();
> System.out.println(String.format("Connected to cluster '%s' on
> %s.", metadata.getClusterName(), metadata.getAllHosts()));
>
> } catch (NoHostAvailableException e) {
> System.out.println("NoHostAvailableException");
> e.printStackTrace();
> System.out.println(e.getErrors());
> } catch (Exception e) {
> System.out.println("Exception");
> e.printStackTrace();
> }
> }
>
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