Cassandra - Drop Keyspace

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Dropping a Keyspace

You can drop a KeySpace using the command DROP KEYSPACE. Given below is the syntax for dropping a KeySpace.

Syntax

DROP KEYSPACE <identifier>

i.e.

DROP KEYSPACE “KeySpace name”

Example

The following code deletes the keyspace howcodex.

cqlsh> DROP KEYSPACE howcodex;

Verification

Verify the keyspaces using the command Describe and check whether the table is dropped as shown below.

cqlsh> DESCRIBE keyspaces;

system system_traces

Since we have deleted the keyspace howcodex, you will not find it in the keyspaces list.

Dropping a Keyspace using Java API

You can create a keyspace using the execute() method of Session class. Follow the steps given below to drop a keyspace using Java API.

Step1: Create a Cluster Object

First of all, create an instance of Cluster.builder class of com.datastax.driver.core package as shown below.

//Creating Cluster.Builder object 
Cluster.Builder builder1 = Cluster.builder();

Add a contact point (IP address of the node) using the addContactPoint() method of Cluster.Builder object. This method returns Cluster.Builder.

//Adding contact point to the Cluster.Builder object
Cluster.Builder builder2 = build.addContactPoint( "127.0.0.1" );

Using the new builder object, create a cluster object. To do so, you have a method called build() in the Cluster.Builder class. The following code shows how to create a cluster object.

//Building a cluster
Cluster cluster = builder.build();

You can build a cluster object using a single line of code as shown below.

Cluster cluster = Cluster.builder().addContactPoint("127.0.0.1").build();

Step 2: Create a Session Object

Create an instance of Session object using the connect() method of Cluster class as shown below.

Session session = cluster.connect( );

This method creates a new session and initializes it. If you already have a keyspace, you can set it to the existing one by passing the keyspace name in string format to this method as shown below.

Session session = cluster.connect(“ Your keyspace name”);

Step 3: Execute Query

You can execute CQL queries using the execute() method of Session class. Pass the query either in string format or as a Statement class object to the execute() method. Whatever you pass to this method in string format will be executed on the cqlsh.

In the following example, we are deleting a keyspace named tp. You have to store the query in a string variable and pass it to the execute() method as shown below.

String query = "DROP KEYSPACE tp; ";

session.execute(query);

Given below is the complete program to create and use a keyspace in Cassandra using Java API.

import com.datastax.driver.core.Cluster;
import com.datastax.driver.core.Session;

public class Drop_KeySpace {

   public static void main(String args[]){

      //Query
      String query = "Drop KEYSPACE tp";

      //creating Cluster object
      Cluster cluster = Cluster.builder().addContactPoint("127.0.0.1").build();
    
      //Creating Session object
      Session session = cluster.connect();
    
      //Executing the query
      session.execute(query);
      System.out.println("Keyspace deleted");
   }
}

Save the above program with the class name followed by .java, browse to the location where it is saved. Compile and execute the program as shown below.

$javac Delete_KeySpace.java
$java Delete_KeySpace

Under normal conditions, it should produce the following output −

Keyspace deleted
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