What Is a Indexes on Collections in Apache Cassandra?
A supported secondary index can expose collection elements or map keys/values for membership queries. Syntax and operators depend on index type and Cassandra release.
How the Indexes on Collections Algorithm Works
A supported secondary index can expose collection elements or map keys/values for membership queries. Syntax and operators depend on index type and Cassandra release.
When to Use Indexes on Collections
Bounded collection membership searches where SAI or the selected index explicitly supports that collection.
How to Create a Apache Cassandra Indexes on Collections
Review data quality, existing structures, feature support, build time, and deployment requirements before creating an index on a production table.
CREATE CUSTOM INDEX IF NOT EXISTS tags_sai ON articles (tags) USING 'StorageAttachedIndex';Indexes on Collections Query Example
This example demonstrates the matching query shape. Check the execution plan to confirm that the engine can use the index.
SELECT article_id FROM articles WHERE tags CONTAINS 'database';Queries Supported by Indexes on Collections
Bounded collection membership searches where SAI or the selected index explicitly supports that collection. A similar-looking predicate may not use the same access path; operators, expressions, key order, and data type all matter.
Read Performance, Storage, and Write Costs
Each element can add index storage and write work; large collections create expensive partitions and updates. Indexes reduce some search work but require storage and add maintenance to writes.
Indexes on Collections Limitations and Common Mistakes
Verify collection type and CONTAINS/CONTAINS KEY support; unbounded collections are not search engines.
Do not assume that an index being present means the optimizer chose it or that the query became selective.
How to Measure and Tune Indexes on Collections
Bound collections, benchmark element counts, and use a query table for frequent independent lookup.
Compare representative plans and timings before and after, including concurrent writes and realistic data volumes.
Indexes on Collections Questions
Will the database always use this index?
No. The optimizer weighs selectivity, estimated costs, statistics, cache state, and the amount of data returned.
What should I verify before production?
Confirm version support, query compatibility, write overhead, build/rollback procedures, and index behavior during backup and recovery.
Official Apache Cassandra Index Documentation
Check Apache Cassandra documentation: Indexing concepts for release-specific requirements and supported operators.