Migrations

Supported Migration Methods

cassandra-migration is designed to support a combination of migration methods:

• Standalone migration via uber-jar or use library API directly as part of your application
• Migrate schema using CQL files, Java classes, or a combination of both
• Configuration via passed-in system properties or centralised in a configuration file

Cluster Coordination

• Schema version tracking statements use ConsistencyLevel.ALL for clustered hosts, otherwise ConsistencyLevel.ONE for single host.
• Users should manage their own consistency level in the migration scripts.

Schema Tracking

Applied schemas are tracked using a migration version table, as follows:

cassandra@cqlsh:cassandra_migration_test> select * from cassandra_migration_version;
 type        | version | checksum    | description    | execution_time | installed_by | installed_on             | installed_rank | script                                 | success | version_rank
-------------+---------+-------------+----------------+----------------+--------------+--------------------------+----------------+----------------------------------------+---------+--------------
         CQL |   1.0.0 |   985950023 |          First |             88 |    cassandra | 2015-09-12 15:10:22-0400 |              1 |                      V1_0_0__First.cql |    True |            1
         CQL |   1.1.2 |  2095193138 |  Late arrival2 |              3 |    cassandra | 2015-09-12 15:10:23-0400 |              5 |              V1_1_2__Late_arrival2.cql |    True |            2
         CQL |   1.1.3 | -1648933960 |  Late arrival3 |             15 |    cassandra | 2015-09-12 15:10:23-0400 |              6 |              V1_1_3__Late_arrival3.cql |    True |            3
         CQL |   2.0.0 |  1899485431 |         Second |            154 |    cassandra | 2015-09-12 15:10:22-0400 |              2 |                     V2_0_0__Second.cql |    True |            4
 JAVA_DRIVER |     3.0 |        null |          Third |              3 |    cassandra | 2015-09-12 15:10:22-0400 |              3 |            migration.integ.V3_0__Third |    True |            5
 JAVA_DRIVER |   3.0.1 |        null | Three zero one |              2 |    cassandra | 2015-09-12 15:10:22-0400 |              4 | migration.integ.V3_0_1__Three_zero_one |    True |            6