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Jason Brown commented on CASSANDRA-13289: ----------------------------------------- bq. There is a part of me that doesn't like having a null field Maybe set the type of the field to {{Optional<AtomicInteger>}}, and set it to {{Optional.empty}} when not being used? Not sure I love this but it does avoid an NPE. bq. I don't want to throw an error at the request level. I can't validate the configuration. And I don't want to silently not increment the counters. I agree with these points, especially the last. I suspect not counting would be confusing to an operator who went out of their way to enable this feature, and are expecting an output of some kind. I don't think logging is necessary (or helpful). wrt timeouts, you are correct. I think I was forgetting that this patch is only affecting the write path, and I must have been thinking the read path was pulled along, as well. Either way, this concern is not a real issue. I'll rereview the ticket now with these things in mind. > Make it possible to monitor an ideal consistency level separate from actual > consistency level > --------------------------------------------------------------------------------------------- > > Key: CASSANDRA-13289 > URL: https://issues.apache.org/jira/browse/CASSANDRA-13289 > Project: Cassandra > Issue Type: New Feature > Components: Core > Reporter: Ariel Weisberg > Assignee: Ariel Weisberg > Fix For: 4.0 > > > As an operator there are several issues related to multi-datacenter > replication and consistency you may want to have more information on from > your production database. > For instance. If your application writes at LOCAL_QUORUM how often are those > writes failing to achieve EACH_QUORUM at other data centers. If you failed > your application over to one of those data centers roughly how inconsistent > might it be given the number of writes that didn't propagate since the last > incremental repair? > You might also want to know roughly what the latency of writes would be if > you switched to a different consistency level. For instance you are writing > at LOCAL_QUORUM and want to know what would happen if you switched to > EACH_QUORUM. > The proposed change is to allow an ideal_consistency_level to be specified in > cassandra.yaml as well as get/set via JMX. If no ideal consistency level is > specified no additional tracking is done. > if an ideal consistency level is specified then the > {{AbstractWriteResponesHandler}} will contain a delegate WriteResponseHandler > that tracks whether the ideal consistency level is met before a write times > out. It also tracks the latency for achieving the ideal CL of successful > writes. > These two metrics would be reported on a per keyspace basis. -- This message was sent by Atlassian JIRA (v6.3.15#6346)