About schema changes
In Cassandra 1.2 and later, large numbers of schema changes can simultaneously take place in a cluster without any schema disagreement among nodes. For example, if one client sets a column to an integer and another client sets the column to text, one or the another action will be instantly agreed upon. Which action is agreed upon is unpredictable.
The new schema resolution design eliminates delays caused by schema changes when a new node joins the cluster. As soon as the node joins the cluster, it receives the current schema with instantaneous reconciliation of changes.