ScyllaDB University LIVE, FREE Virtual Training Event | March 21
Register for Free
ScyllaDB Documentation Logo Documentation
  • Server
  • Cloud
  • Tools
    • ScyllaDB Manager
    • ScyllaDB Monitoring Stack
    • ScyllaDB Operator
  • Drivers
    • CQL Drivers
    • DynamoDB Drivers
  • Resources
    • ScyllaDB University
    • Community Forum
    • Tutorials
Download
ScyllaDB Docs ScyllaDB Enterprise Features Global Secondary Indexes

Caution

You're viewing documentation for a previous version. Switch to the latest stable version.

Global Secondary Indexes¶

The data model in ScyllaDB partitions data between cluster nodes using a partition key, which is defined in the database schema. This is an efficient way to look up rows because you can find the node hosting the row by hashing the partition key.

However, this also means that finding a row using a non-partition key requires a full table scan which is inefficient.

Global Secondary indexes (named “Secondary indexes” for the rest of this doc) are a mechanism in ScyllaDB which allows efficient searches on non-partition keys by creating an index. They are indexes created on columns other than the entire partition key, where each secondary index indexes one specific column. A secondary index can index a column used in the partition key in the case of a composite partition key.

Secondary indexes provide the following advantages:

  1. Secondary Indexes are (mostly) transparent to your application. Queries have access to all the columns in the table, and you can add or remove indexes on the fly without changing the application.

  2. We can use the value of the indexed column to find the corresponding index table row in the cluster so that reads are scalable.

  3. Updates can be more efficient with secondary indexes than materialized views because only changes to the primary key and indexed column cause an update in the index view.

What’s more, the size of an index is proportional to the size of the indexed data. As data in ScyllaDB is distributed to multiple nodes, it’s impractical to store the whole index on a single node, as it limits the size of the index to the capacity of a single node, not the capacity of the whole cluster.

For this reason, secondary indexes in ScyllaDB are global rather than local. With global indexing, a materialized view is created for each index. This materialized view has the indexed column as a partition key and primary key (partition key and clustering keys) of the indexed row as clustering keys.

Secondary indexes created globally provide a further advantage: you can use the value of the indexed column to find the corresponding index table row in the cluster so reads are scalable. Note however, that with this approach, writes are slower than with local indexing because of the overhead required to keep the indexed view up to date.

How Secondary Index Queries Work¶

ScyllaDB breaks indexed queries into two parts:

  1. a query on the index table to retrieve partition keys for the indexed table, and

  2. a query to the indexed table using the retrieved partition keys.

Secondary Index Flow

In the example above:

  1. The query arrives to a coordinator

  2. The node notices the query on an index column and issues a read to an index table, which has the index table row for the base table

  3. This query will return a partition key for the base table that is used to retrieve contents of the base table.

Example¶

The following is an example and does not contain all of the options available. To see all of the options available, refer to the CQL Reference.

Given the following schema:

CREATE TABLE buildings  (name text, city text, height int, PRIMARY KEY (name));

Let’s populate it with some test data:

INSERT INTO buildings(name,city,height) VALUES ('Burj Khalifa','Dubai',828);
INSERT INTO buildings(name,city,height) VALUES ('Shanghai Tower','Shanghai',632);
INSERT INTO buildings(name,city,height) VALUES ('Abraj Al-Bait Clock Tower','Mecca',601);
INSERT INTO buildings(name,city,height) VALUES ('Ping An Finance Centre','Shenzhen',599);
INSERT INTO buildings(name,city,height) VALUES ('Lotte World Tower','Seoul',554);
INSERT INTO buildings(name,city,height) VALUES ('One World Trade Center','New York City',541);
INSERT INTO buildings(name,city,height) VALUES ('Guangzhou CTF Finance Centre','Guangzhou',530);
INSERT INTO buildings(name,city,height) VALUES ('Tianjin CTF Finance Centre','Tianjin',530);
INSERT INTO buildings(name,city,height) VALUES ('China Zun','Beijing',528);
INSERT INTO buildings(name,city,height) VALUES ('Taipei 101','Taipei',508);

Note that if we try to query on a column (the part after the WHERE clause) in a ScyllaDB table that isn’t part of the primary key, we’ll see that this is not permitted. For example:

SELECT * FROM buildings WHERE city = 'Shenzhen';

will result in an error.

Secondary indexes are designed to allow efficient querying of non-partition key columns. We can create an index on city by with the following CQL statements:

CREATE INDEX buildings_by_city ON buildings (city);

We can now query the indexed columns as if they were partition keys:

SELECT * FROM buildings WHERE city = 'Shenzhen';

returns

name                   | city     | height
-----------------------+----------+--------
Ping An Finance Centre | Shenzhen |    599

(1 rows)

Note that you can use the DESCRIBE command to see the whole schema for the buildings table, including created indexes and views:

cqlsh:mykeyspace> DESC buildings;

CREATE TABLE mykeyspace.buildings (
             name text PRIMARY KEY,
             city text,
             height int
) WITH bloom_filter_fp_chance = 0.01
AND caching = {'keys': 'ALL', 'rows_per_partition': 'ALL'}
...;

CREATE INDEX buildings_by_city ON mykeyspace.buildings (city);

CREATE MATERIALIZED VIEW mykeyspace.buildings_by_city_index AS
SELECT city, idx_token, name
FROM mykeyspace.buildings
WHERE city IS NOT NULL
PRIMARY KEY (city, idx_token, name)
WITH CLUSTERING ORDER BY (idx_token ASC, name ASC)
AND bloom_filter_fp_chance = 0.01
AND caching = {'keys': 'ALL', 'rows_per_partition': 'ALL'}
...

Note the Secondary Index is implemented as MATERIALIZED VIEW.

More information¶

  • Local Secondary Indexes

  • CQL Reference - CQL Reference for Secondary Indexes

The following courses are available from ScyllaDB University:

  • Materialized Views and Secondary Indexes

  • Global Secondary Indexes

Was this page helpful?

PREVIOUS
Lightweight Transactions
NEXT
Local Secondary Indexes
  • Create an issue

On this page

  • Global Secondary Indexes
    • How Secondary Index Queries Work
    • Example
    • More information
ScyllaDB Enterprise
  • enterprise
    • 2024.2
    • 2024.1
    • 2023.1
    • 2022.2
  • Getting Started
    • Install ScyllaDB Enterprise
      • ScyllaDB Web Installer for Linux
      • Install ScyllaDB Without root Privileges
      • Install scylla-jmx Package
      • Air-gapped Server Installation
      • ScyllaDB Housekeeping and how to disable it
      • ScyllaDB Developer Mode
      • Launch ScyllaDB on AWS
      • Launch ScyllaDB on GCP
      • Launch ScyllaDB on Azure
    • Configure ScyllaDB
    • ScyllaDB Configuration Reference
    • ScyllaDB Requirements
      • System Requirements
      • OS Support
      • Cloud Instance Recommendations
      • ScyllaDB in a Shared Environment
    • Migrate to ScyllaDB
      • Migration Process from Cassandra to ScyllaDB
      • ScyllaDB and Apache Cassandra Compatibility
      • Migration Tools Overview
    • Integration Solutions
      • Integrate ScyllaDB with Spark
      • Integrate ScyllaDB with KairosDB
      • Integrate ScyllaDB with Presto
      • Integrate ScyllaDB with Elasticsearch
      • Integrate ScyllaDB with Kubernetes
      • Integrate ScyllaDB with the JanusGraph Graph Data System
      • Integrate ScyllaDB with DataDog
      • Integrate ScyllaDB with Kafka
      • Integrate ScyllaDB with IOTA Chronicle
      • Integrate ScyllaDB with Spring
      • Shard-Aware Kafka Connector for ScyllaDB
      • Install ScyllaDB with Ansible
      • Integrate ScyllaDB with Databricks
      • Integrate ScyllaDB with Jaeger Server
      • Integrate ScyllaDB with MindsDB
    • Tutorials
  • ScyllaDB for Administrators
    • Administration Guide
    • Procedures
      • Cluster Management
      • Backup & Restore
      • Change Configuration
      • Maintenance
      • Best Practices
      • Benchmarking ScyllaDB
      • Migrate from Cassandra to ScyllaDB
      • Disable Housekeeping
    • Security
      • ScyllaDB Security Checklist
      • Enable Authentication
      • Enable and Disable Authentication Without Downtime
      • Creating a Custom Superuser
      • Generate a cqlshrc File
      • Reset Authenticator Password
      • Enable Authorization
      • Grant Authorization CQL Reference
      • Certificate-based Authentication
      • Role Based Access Control (RBAC)
      • ScyllaDB Auditing Guide
      • Encryption: Data in Transit Client to Node
      • Encryption: Data in Transit Node to Node
      • Generating a self-signed Certificate Chain Using openssl
      • Configure SaslauthdAuthenticator
      • Encryption at Rest
      • LDAP Authentication
      • LDAP Authorization (Role Management)
      • Software Bill Of Materials (SBOM)
    • Admin Tools
      • Nodetool Reference
      • CQLSh
      • Admin REST API
      • Tracing
      • ScyllaDB SStable
      • ScyllaDB Types
      • SSTableLoader
      • cassandra-stress
      • SSTabledump
      • SSTableMetadata
      • ScyllaDB Logs
      • Seastar Perftune
      • Virtual Tables
      • Reading mutation fragments
      • Maintenance socket
      • Maintenance mode
      • Task manager
    • Version Support Policy
    • ScyllaDB Monitoring Stack
    • ScyllaDB Operator
    • ScyllaDB Manager
    • Upgrade Procedures
      • About Upgrade
      • Upgrade Guides
    • System Configuration
      • System Configuration Guide
      • scylla.yaml
      • ScyllaDB Snitches
    • Benchmarking ScyllaDB
    • ScyllaDB Diagnostic Tools
  • ScyllaDB for Developers
    • Develop with ScyllaDB
    • Tutorials and Example Projects
    • Learn to Use ScyllaDB
    • ScyllaDB Alternator
    • ScyllaDB Drivers
      • ScyllaDB CQL Drivers
      • ScyllaDB DynamoDB Drivers
  • CQL Reference
    • CQLSh: the CQL shell
    • Appendices
    • Compaction
    • Consistency Levels
    • Consistency Level Calculator
    • Data Definition
    • Data Manipulation
      • SELECT
      • INSERT
      • UPDATE
      • DELETE
      • BATCH
    • Data Types
    • Definitions
    • Global Secondary Indexes
    • Expiring Data with Time to Live (TTL)
    • Functions
    • Wasm support for user-defined functions
    • JSON Support
    • Materialized Views
    • Non-Reserved CQL Keywords
    • Reserved CQL Keywords
    • DESCRIBE SCHEMA
    • Service Levels
    • ScyllaDB CQL Extensions
  • Features
    • Lightweight Transactions
    • Global Secondary Indexes
    • Local Secondary Indexes
    • Materialized Views
    • Counters
    • Change Data Capture
      • CDC Overview
      • The CDC Log Table
      • Basic operations in CDC
      • CDC Streams
      • CDC Stream Generations
      • Querying CDC Streams
      • Advanced column types
      • Preimages and postimages
      • Data Consistency in CDC
    • Workload Attributes
    • Workload Prioritization
  • ScyllaDB Architecture
    • Data Distribution with Tablets
    • ScyllaDB Ring Architecture
    • ScyllaDB Fault Tolerance
    • Consistency Level Console Demo
    • ScyllaDB Anti-Entropy
      • ScyllaDB Hinted Handoff
      • ScyllaDB Read Repair
      • ScyllaDB Repair
    • SSTable
      • ScyllaDB SSTable - 2.x
      • ScyllaDB SSTable - 3.x
    • Compaction Strategies
    • Raft Consensus Algorithm in ScyllaDB
    • Zero-token Nodes
  • Troubleshooting ScyllaDB
    • Errors and Support
      • Report a ScyllaDB problem
      • Error Messages
      • Change Log Level
    • ScyllaDB Startup
      • Ownership Problems
      • ScyllaDB will not Start
      • ScyllaDB Python Script broken
    • Upgrade
      • Inaccessible configuration files after ScyllaDB upgrade
    • Cluster and Node
      • Handling Node Failures
      • Failure to Add, Remove, or Replace a Node
      • Failed Decommission Problem
      • Cluster Timeouts
      • Node Joined With No Data
      • NullPointerException
      • Failed Schema Sync
    • Data Modeling
      • ScyllaDB Large Partitions Table
      • ScyllaDB Large Rows and Cells Table
      • Large Partitions Hunting
      • Failure to Update the Schema
    • Data Storage and SSTables
      • Space Utilization Increasing
      • Disk Space is not Reclaimed
      • SSTable Corruption Problem
      • Pointless Compactions
      • Limiting Compaction
    • CQL
      • Time Range Query Fails
      • COPY FROM Fails
      • CQL Connection Table
    • ScyllaDB Monitor and Manager
      • Manager and Monitoring integration
      • Manager lists healthy nodes as down
    • Installation and Removal
      • Removing ScyllaDB on Ubuntu breaks system packages
  • Knowledge Base
    • Upgrading from experimental CDC
    • Compaction
    • Consistency in ScyllaDB
    • Counting all rows in a table is slow
    • CQL Query Does Not Display Entire Result Set
    • When CQLSh query returns partial results with followed by “More”
    • Run ScyllaDB and supporting services as a custom user:group
    • Customizing CPUSET
    • Decoding Stack Traces
    • Snapshots and Disk Utilization
    • DPDK mode
    • Debug your database with Flame Graphs
    • Efficient Tombstone Garbage Collection in ICS
    • How to Change gc_grace_seconds for a Table
    • Gossip in ScyllaDB
    • Increase Permission Cache to Avoid Non-paged Queries
    • How does ScyllaDB LWT Differ from Apache Cassandra ?
    • Map CPUs to ScyllaDB Shards
    • ScyllaDB Memory Usage
    • NTP Configuration for ScyllaDB
    • Updating the Mode in perftune.yaml After a ScyllaDB Upgrade
    • POSIX networking for ScyllaDB
    • ScyllaDB consistency quiz for administrators
    • Recreate RAID devices
    • How to Safely Increase the Replication Factor
    • ScyllaDB and Spark integration
    • Increase ScyllaDB resource limits over systemd
    • ScyllaDB Seed Nodes
    • How to Set up a Swap Space
    • ScyllaDB Snapshots
    • ScyllaDB payload sent duplicated static columns
    • Stopping a local repair
    • System Limits
    • How to flush old tombstones from a table
    • Time to Live (TTL) and Compaction
    • ScyllaDB Nodes are Unresponsive
    • Update a Primary Key
    • Using the perf utility with ScyllaDB
    • Configure ScyllaDB Networking with Multiple NIC/IP Combinations
  • Reference
    • AWS Images
    • Azure Images
    • GCP Images
    • Configuration Parameters
    • Glossary
    • Limits
    • ScyllaDB Enterprise vs. Open Source Matrix
    • API Reference (BETA)
    • Metrics (BETA)
  • ScyllaDB University
  • ScyllaDB FAQ
  • Alternator: DynamoDB API in Scylla
    • Getting Started With ScyllaDB Alternator
    • ScyllaDB Alternator for DynamoDB users
    • Alternator-specific APIs
Docs Tutorials University Contact Us About Us
© 2025, ScyllaDB. All rights reserved. | Terms of Service | Privacy Policy | ScyllaDB, and ScyllaDB Cloud, are registered trademarks of ScyllaDB, Inc.
Last updated on 09 Apr 2025.
Powered by Sphinx 7.4.7 & ScyllaDB Theme 1.8.6