In a 2 DC deployment, When we use the consistency serial for Light Weight Transactions, does Cassandra pick a DC as a master DC to serialize the transactions?
In a 2 DC deployment, When we use the consistency serial for Light Weight Transactions, does Cassandra pick a DC as a master DC to serialize the transactions?
@papishetty.praneeth_19978 There is no concept of master/slave in Cassandra. Cassandra also doesn't "serialize" LWTs.
The SERIAL
consistency is used in the read part of the read-before-write to satisfy the condition for the lightweight transaction. It lets C* read the current version of the data and if it encounters a write for the data which is still in progress, it commits the data as part of the read before returning a result.
At SERIAL
consistency, it does not enlist nodes from a "master" DC. Instead it reads from a QUORUM
of nodes (regardless of the DC they belong to) in order to satisfy the request. Cheers!
That was my understanding too. I was confused when I saw high ClientRequestLatencies only in one region. If a write comes in to DC "A" with serial as a consistency instead of local_serial, it might hit the cross DC "B" and the same happens when a write comes to DC "B" . Ok let me pull some more metrics from the service side .
Thanks you very much for the reply .
5 People are following this question.
Why do we need SERIAL consistency level?
Cannot start Cassandra due to "Unexpected disk state: failed to read transaction log"
What is the maximum size of a table in Cassandra?
What is the recommendation for separating OLTP and OLAP workloads in Cassandra?
Why is the consistency level changing from LOCAL_QUORUM to TWO?
DataStax Enterprise is powered by the best distribution of Apache Cassandra ™
© 2022 DataStax, Titan, and TitanDB are registered trademarks of DataStax, Inc. and its subsidiaries in the United States and/or other countries.
Apache, Apache Cassandra, Cassandra, Apache Tomcat, Tomcat, Apache Lucene, Lucene, Apache Solr, Apache Hadoop, Hadoop, Apache Spark, Spark, Apache TinkerPop, TinkerPop, Apache Kafka and Kafka are either registered trademarks or trademarks of the Apache Software Foundation or its subsidiaries in Canada, the United States and/or other countries.
Privacy Policy Terms of Use