As described in CASSANDRA-10699 (Make schema alterations strongly consistent), concurrent schema changes can still lead to schema disagreement in Cassandra 3.0. In order to properly support Elasticsearch dynamic mapping in Elassandra, we will see how multiple schema changes are validated on a working copy of the Cassandra schema, and applied in an atomic update to all nodes if a light weight transaction succeed, thus avoiding concurrent schema changes issue. I will also explain how we have taken advantage of Cassandra table extensions to store the Elasticsearch mapping directly into the CQL schema with several benefits.
Consistent Cassandra schema changes in Elassandra Vincent Royer
September 12, 2019