cassmig

Cassadra java schema migrator that uses the datastax driver and requires a datastax Session ##Maven dependency

<dependency>
    <groupId>com.github.ecyshor</groupId>
    <artifactId>cassandra-migration</artifactId>
    <version>1.1.5</version>
</dependency>

##Migration files The migration files are of two types: ####Initialization file: This contains all the cql queries that must be executed before creating the migrations table. Only one if these files must be configured. It has the following format:

--keyspace=marguerita                     #the keyspace where the migrations table will be executed
--migration_init=public                   #marks that this is the initilization file and specifies the schema name
--description=Initial keyspace creation   #description of the migration file
--start                                   #marks the start of the migrations queries
    CREATE KEYSPACE marguerita WITH replication = {'class':'SimpleStrategy', 'replication_factor':1};
--end                                     #marks the end of the migrations queries

Please make sure that the schema name that you provide is unique. All the keys presented are required. ####Migration files: These contain the actual migrations:

--order=1                                 #The order of the migration file. Files with lower order will be applied first. If there are two files with the same order one will execute before the other. You cannot exactly tell which one will execute first but no matter how many time it will be executed, it will always be executed first. This must be a positive integer.
--keyspace=marguerita                     #The keyspace where the migration will run. This will cause the first command the be executed to be `USE marguerita`
--description=Create the first table      #description of the migration file
--start                                   #marks the start of the migrations queries

CREATE TABLE drinks (
  salt bigint,
  column uuid,
  email varchar,
  PRIMARY KEY (salt, email)
);

--end                                     #marks the end of the migrations queries

We can have any number of normal migration files

##Usage

###To migrate from a project which will not be used as a dependency by another project

CassandraMigrator migrator = new CassandraMigrator(session);
migrator.migrate("migrations");

The migrations will be loaded from the classpath. The required session is of type com.datastax.driver.core.Session;

###To migrate using files found in external modules/dependencies

CassandraMigrator migrator = new CassandraMigrator(session);
migrator.migrateExternal("com.example","migrations");

this uses reflection to search for the files
"migrations" represents the prefix for the migrations files that should be searched. If in an external dependency, this should be the folder where the files are located. Please take note that this should be the prefix
"com.example" represents the packages prefix for libraries where we should scan for files.

ecyshor/cassmig

cassmig