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 Open Source Features Local Secondary Indexes

Caution

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

Local Secondary Indexes¶

Local Secondary Indexes is an enhancement to Global Secondary Indexes, which allows ScyllaDB to optimize workloads where the partition key of the base table and the index are the same key.

Note

As of ScyllaDB Open Source 4.0, updates for local secondary indexes are performed synchronously. When updates are synchronous, the client acknowledges the write operation only after both the base table modification and the view update are written. This is important to note because the process is no longer asynchronous and the modifications are immediately reflected in the index. In addition, if the view update fails, the client receives a write error.

Example:

CREATE TABLE menus (location text, name text, price float, dish_type text, PRIMARY KEY(location, name));
CREATE INDEX ON menus((location),dish_type);

As the same partition key is used for the base table (menus) and the Index, one node holds both. When using a Token Aware Driver, the same node is likely the coordinator, and the query does not require any inter-node communication.

How Local Secondary Index Queries Work¶

Lets explore the example above, first with Global Secondary Index (GSI) and then with Local Secondary Index (LSI)

Global Secondary Index Example

CREATE TABLE menus (location text,
      name text, price float,
      dish_type text,
      PRIMARY KEY(location, name));

INSERT INTO menus (location, name, price, dish_type) VALUES ('Reykjavik', 'hakarl', 16, 'cold Icelandic starter');
INSERT INTO menus (location, name, price, dish_type) VALUES ('Reykjavik', 'svid', 21, 'hot Icelandic main dish');
INSERT INTO menus (location, name, price, dish_type) VALUES ('Da Lat', 'banh mi', 5, 'Vietnamese breakfast');
INSERT INTO menus (location, name, price, dish_type) VALUES ('Ho Chi Minh', 'goi cuon', 6, 'Vietnamese hot starter');
INSERT INTO menus (location, name, price, dish_type) VALUES ('Warsaw', 'sorrel soup', 5, 'Polish soup');


CREATE INDEX ON menus(dish_type);

The create Index does not include the base partition key. As a result, the following query will work, but in an inefficient manner:

SELECT * FROM menus WHERE location = 'Warsaw' and dish_type = 'Polish soup';

With GSI, dish_type acts as the partition key of the index table and the query requires two inter-node hops

../_images/global-sec-index-example.png

GSI flow:

  • The user provides query details to the coordinator node (1)

  • An indexing subquery (2) is used to fetch all matching base keys from the materialized view.

  • The coordinator uses the resulting base key set to request appropriate rows from the base table (3).

Note, that partition keys from the base table and underlying materialized view are different, which means that their data is likely to be stored on different nodes.

Local Secondary Index Example Now let’s create an LSI, using the base table partition key, in this case location as partition key for the Index

CREATE INDEX ON menus((location), dish_type);
SELECT * FROM menus WHERE location = 'Warsaw' and dish_type = 'Polish soup';

The same query can be done to one node, as the Index and Base table partitions are guaranteed to be on the same node.

../_images/local-sec-index-example.png

LSI flow:

  • The user provides query details to the coordinator node (1)

  • An indexing subquery (2) is used to fetch all matching base keys from the underlying materialized view.

  • The coordinator uses the resulting base key set to request appropriate rows from the base table (3), located in the same node as the Index

Both the base table and the underlying materialized view have the same partition keys for corresponding rows. That means that their data resides on the same node and can thus be executed locally, without having to contact another node. When using a token aware policy, the entire query will be done with zero inter-node communication.

../_images/local-sec-index-token-aware-exaple.png

LSI with Token Aware driver flow:

  • The user provides query details to the coordinator node (1)

  • The same(2) node:

    1. Act as the Coordinator

    2. Holds the Index

    3. Holds the base table

The coordinator processes the request for the index and base table internally and returns the value to the client with zero inter-node messaging.

Note

When the same table has both LSI and GSI, ScyllaDB will automatically use the right Index for each query.

When should you use a Local Secondary Index¶

  • When your Index query includes the base table partition key.

More information¶

  • Global Secondary Indexes

  • CQL Reference - CQL Reference for Secondary Indexes

The following courses are available from ScyllaDB University:

  • Materialized Views and Secondary Indexes

  • Local Secondary Indexes

Was this page helpful?

PREVIOUS
Global Secondary Indexes
NEXT
ScyllaDB Materialized Views
  • Create an issue
  • Edit this page

On this page

  • Local Secondary Indexes
    • How Local Secondary Index Queries Work
    • When should you use a Local Secondary Index
    • More information
ScyllaDB Open Source
  • 6.2
    • master
    • 6.2
    • 6.1
    • 6.0
    • 5.4
    • 5.2
    • 5.1
  • Getting Started
    • Install ScyllaDB
      • Launch ScyllaDB on AWS
      • Launch ScyllaDB on GCP
      • Launch ScyllaDB on Azure
      • ScyllaDB Web Installer for Linux
      • Install ScyllaDB Linux Packages
      • Install scylla-jmx Package
      • Run ScyllaDB in Docker
      • Install ScyllaDB Without root Privileges
      • Air-gapped Server Installation
      • ScyllaDB Housekeeping and how to disable it
      • ScyllaDB Developer Mode
    • Configure ScyllaDB
    • ScyllaDB Configuration Reference
    • ScyllaDB Requirements
      • System Requirements
      • OS Support by Linux Distributions and Version
      • 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)
      • Encryption: Data in Transit Client to Node
      • Encryption: Data in Transit Node to Node
      • Generating a self-signed Certificate Chain Using openssl
      • Configure SaslauthdAuthenticator
    • 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
    • ScyllaDB Monitoring Stack
    • ScyllaDB Operator
    • ScyllaDB Manager
    • Upgrade Procedures
      • ScyllaDB Versioning
      • ScyllaDB Open Source Upgrade
      • ScyllaDB Open Source to ScyllaDB Enterprise Upgrade
      • ScyllaDB Image
      • ScyllaDB Enterprise
    • 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
    • Service Levels
    • ScyllaDB CQL Extensions
  • Alternator: DynamoDB API in Scylla
    • Getting Started With ScyllaDB Alternator
    • ScyllaDB Alternator for DynamoDB users
  • 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
  • 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
    • 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
    • API Reference (BETA)
    • Metrics (BETA)
  • ScyllaDB FAQ
  • Contribute to ScyllaDB
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 08 May 2025.
Powered by Sphinx 7.4.7 & ScyllaDB Theme 1.8.6