Couchbase

Couchbase works as a Key-Value store (managed memory cache) + Document Database. It is famous for its "memory-first" architecture and N1QL (SQL for JSON).

When to Use

• Caching + Persistence: When you need the speed of Redis but the persistence/querying of MongoDB.
• Mobile Sync: Couchbase Mobile / Sync Gateway provides robust offline-sync for mobile apps.
• SQL on JSON: N1QL allows using standard SQL (SELECT * FROM users JOIN orders) on JSON documents.

Quick Start

-- N1QL Query
SELECT u.name, ARRAY_AGG(o.item) as orders
FROM `travel-sample`.inventory.users u
JOIN `travel-sample`.inventory.orders o ON u.id = o.user_id
WHERE u.city = "Paris"
GROUP BY u.name;

Core Concepts

Memory First

Writes go to memory first (microseconds), then disk. Reads serve from memory if hot.

Couchbase Capella

The fully managed Database-as-a-Service (DBaaS) version. Best for 2025 usage.

Buckets, Scopes, Collections

Hierarchy: Cluster -> Bucket -> Scope -> Collection -> Document. Maps roughly to Database -> Schema -> Table -> Row.

Best Practices (2025)

Do:

• Index N1QL queries: Like a relational DB, specific queries need specific GSI (Global Secondary Indexes).
• Use Vector Search: 2025 versions support Vector Search for AI apps.

Don't:

• Don't use Views: Old MapReduce Views are deprecated. Use N1QL.

References

• Couchbase Documentation