How to Create and Drop Indexes in Apache Cassandra

Last updated on May 30 2022
Lalit Kolgaonkar

Table of Contents

How to Create and Drop Indexes in Apache Cassandra

Cassandra – Create Index

Creating an Index using Cqlsh

You can create an index in Cassandra using the command CREATE INDEX. Its syntax is as follows −

CREATE INDEX <identifier> ON <tablename>

Given below is an example to create an index to a column. Here we are creating an index to a column ‘emp_name’ in a table named emp.

cqlsh:tecklearn> CREATE INDEX name ON emp1 (emp_name);

Creating an Index using Java API

You can create an index to a column of a table using the execute() method of Session class. Follow the steps given below to create an index to a column in a table.

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 the 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, then 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 ” );

Here we are using the KeySpace called tp. Therefore, create the session object as shown below.

Session session = cluster.connect(“ tp” );

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 creating an index to a column called emp_name, in a table named emp. You have to store the query in a string variable and pass it to the execute() method as shown below.

//Query

String query = “CREATE INDEX name ON emp1 (emp_name);”;

session.execute(query);

Given below is the complete program to create an index of a column in a table in Cassandra using Java API.

import com.datastax.driver.core.Cluster;

import com.datastax.driver.core.Session;

 

public class Create_Index {

 

public static void main(String args[]){

 

//Query

String query = “CREATE INDEX name ON emp1 (emp_name);”;

Cluster cluster = Cluster.builder().addContactPoint(“127.0.0.1”).build();

 

//Creating Session object

Session session = cluster.connect(“tp”);

 

//Executing the query

session.execute(query);

System.out.println(“Index created”);

}

}

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 Create_Index.java

$java Create_Index

Under normal conditions, it should produce the following output −

Index created

Cassandra – Drop Index

Dropping an Index

You can drop an index using the command DROP INDEX. Its syntax is as follows −

DROP INDEX <identifier>

Given below is an example to drop an index of a column in a table. Here we are dropping the index of the column name in the table emp.

cqlsh:tp> drop index name;

Dropping an Index using Java API

You can drop an index of a table using the execute() method of Session class. Follow the steps given below to drop an index from a table.

Step1: Create a Cluster Object

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, then 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 ” );

Here we are using the KeySpace named tp. Therefore, create the session object as shown below.

Session session = cluster.connect(“ tp” );

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 dropping an index “name” of emp table. You have to store the query in a string variable and pass it to the execute() method as shown below.

//Query

String query = “DROP INDEX user_name;”;

session.execute(query);

Given below is the complete program to drop an index in Cassandra using Java API.

import com.datastax.driver.core.Cluster;

import com.datastax.driver.core.Session;

 

public class Drop_Index {

 

public static void main(String args[]){

 

//Query

String query = “DROP INDEX user_name;”;

 

//Creating cluster object

Cluster cluster = Cluster.builder().addContactPoint(“127.0.0.1”).build();.

 

//Creating Session object

Session session = cluster.connect(“tp”);

 

//Executing the query

session.execute(query);

 

System.out.println(“Index dropped”);

}

}

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 Drop_index.java

$java Drop_index

Under normal conditions, it should produce the following output −

Index dropped

 

So, this brings us to the end of blog. This Tecklearn ‘How to Create and Drop Indexes in Apache Cassandra’ helps you with commonly asked questions if you are looking out for a job in Cassandra and No-SQL Database Domain.

If you wish to learn HBase and build a career in Cassandra or No-SQL Database domain, then check out our interactive, Apache Cassandra Training, that comes with 24*7 support to guide you throughout your learning period. Please find the link for course details:

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Introduction to Big Data, and Cassandra

  • What is Big Data
  • Limitations of RDBMS
  • NoSQL and it’s Characteristics
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  • Basic concepts of Cassandra
  • Features of Cassandra

Cassandra Data model, Installation and setup

  • Installation of Cassandra
  • Key concepts and deployment of non-relational database, column-oriented database, Data Model – column, column family

Cassandra Architecture

  • Explain the Architecture of Cassandra
  • Different Layers of Cassandra Architecture
  • Partitioning and Snitches
  • Explain Vnodes and How Read and Write Path works
  • Understand Compaction, Anti-Entropy and Tombstone
  • Describe Repairs in Cassandra

Deep Dive into Cassandra Database

  • Describe Different Data Types Used in Cassandra
  • Explain Collection Types
  • Describe What are CRUD Operations
  • Implement Insert, Select, Update and D        elete of various elements
  • Implement Various Functions Used in Cassandra
  • Describe Importance of Roles and Indexing

Backup & Restore and Performance Tuning

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  • Create a snapshot using Nodetool utility
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  • Understand all the logs created by Cassandra
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  • Integration with Spark and Kafka

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  • Modelling data around queries
  • Creating table for data queries

Deploying the IDE for Cassandra applications

  • Learning key drivers
  • Deploying the IDE for Cassandra applications and cluster connection
  • Data query implementation

Cassandra Administration

  • Understanding Node Tool Utility
  • Cluster management using Command Line Interface
  • Management and Monitoring using DataStax Ops Center

Cassandra API and Summarization

  • Cassandra client connectivity
  • Connection pool internals
  • Cassandra API
  • Features and concepts of Hector client
  • Thrift, JAVA code and Summarization

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