Specifically, this puts us in an awkward position because LOCAL_QUORUM is desirable so that we don't have unnecessary cross-DC traffic from the client by default, but we can't use it because it will cause complete failure if the local DC goes down. And we can't use QUORUM because it would fail if there's not a quorum in either DC (as would happen if one DC goes down). So it seems like we are forced to use a lesser consistency such as ONE or TWO.
-Shannon From: Shannon Carey <sca...@expedia.com<mailto:sca...@expedia.com>> Date: Monday, March 20, 2017 at 5:25 PM To: "user@cassandra.apache.org<mailto:user@cassandra.apache.org>" <user@cassandra.apache.org<mailto:user@cassandra.apache.org>> Subject: Consistency Level vs. Retry Policy when no local nodes are available I am running DSE 5.0, and I have a Java client using the Datastax 3.0.0 client library. The client is configured to use a DCAwareRoundRobinPolicy wrapped in a TokenAwarePolicy. Nothing special. When I run my query, I set a custom retry policy. I am testing cross-DC failover. I have disabled connectivity to the "local" DC (relative to my client) in order to perform the test. When I run a query with the first consistency level set to LOCAL_ONE (or local anything), my retry policy is never called and I always get this exception: "com.datastax.driver.core.exceptions.NoHostAvailableException: All host(s) tried for query failed (no host was tried)" getErrors() on the exception is empty. This is contrary to my expectation that the first attempt would fail and would allow my RetryPolicy to attempt a different (non-LOCAL) consistency level. I have no choice but to avoid using any kind of LOCAL consistency level throughout my applications. Is this expected? Or is there anything I can do about it? Thanks! It certainly seems like a bug to me or at least something that should be improved. -Shannon
