Cassandra automatic schema generator

Question

Firstly, I am new to Cassandra, I came from relational databases. I have used Hibernate API's which made the database related tasks pretty simple. I am using java based drivers from datastax to connect and execute queries. They provided the mapping library which implements JPA. So far so good. I created a model class as follows:

@Table(keyspace = "webscc", name = "t_data", readConsistency = "QUORUM", 
writeConsistency = "QUORUM",caseSensitiveKeyspace = false, 
caseSensitiveTable = false)
public class ChartData {
    @PartitionKey
    private UUID    id;
    @ClusteringColumn(0)
    private Date    timeStamp;
    @ClusteringColumn(1)
    private String  controller; 
    @Column(name = "value")
    private double  value;
    /** Constructors, getters and setters*/
}

Now I want to create a new ChartData object and save it into database. For that, I wanted to implement Mapper.

Session session = Cluster.builder().addContactPoint(props.getProperty(HOSTNAME)).build()
                         .connect(props.getProperty(KEYSPACE));
MappingManager manager = new MappingManager(session);
Mapper<ChartData> mapper = manager.mapper(ChartData.class);
ChartData chartData = new ChartData("controller",24.44);
mapper.save(chartData);

I configured everything, still I could not save ChartData object into table. The problem is it can not create table automatically, although I configured everything in ChartData via annotations. Did I do something wrong, or should I create all required tables manually. Why this does not create database schema automatically like Hibernate does?

Answer 1

Datastax Driver mapper does not create table automatically

There is a open issue On this : https://datastax-oss.atlassian.net/browse/JAVA-569

You have to first create the table manually.

CREATE TABLE webscc.t_data(
    id uuid,
    timestamp timestamp,
    controller text,
    value double,
    PRIMARY KEY (id, timestamp, controller)
);

Or Use the below code after session initialized

session.execute("CREATE TABLE IF NOT EXISTS webscc.t_data(\n" +
        "        id uuid,\n" +
        "        timestamp timestamp,\n" +
        "        controller text,\n" +
        "        value double,\n" +
        "        PRIMARY KEY (id, timestamp, controller)\n" +
        "    )");