A setting that defines a successful write or read by the number of cluster replicas that acknowledge the write or respond to the read request, respectively.
The default consistency is now
CASS_CONSISTENCY_LOCAL_QUORUM for driver
versions 2.2 and above. It was
CASS_CONSISTENCY_ONE for all previous versions
(2.1 and below).
Read and Write Consistency Levels
The consistency level determines the number of replicas on which the read/write must respond/succeed before returning an acknowledgment to the client application. Descriptions and Usage scenarios for each read/write consistency level can be found here.
NOTE: Consistency level
CASS_CONSISTENCY_ANY is only valid for read operation statements.
Setting Consistency Level
A ‘CassStatement’ object can have its consistency level altered at anytime before the statement is executed by the session.
/* Create a simple or prepared statment */ /* Ensure the session executed statement has strong consistency */ cass_statement_set_consistency(statement, CASS_CONSISTENCY_QUORUM);
NOTE: Consistency is ignored for
statements, and some
CASS_CONSISTENCY_ANY aren’t allowed in all situations.