Couchbase

Couchbase is a distributed document database that emerged from the 2011 merger of Membase (built on Memcached) and CouchOne (CouchDB). It combines memcached-compatible caching with JSON-document storage, SQL-style querying via N1QL, full-text search, and analytics — all in one cluster. Couchbase positions itself as a multi-model platform competing with MongoDB on operational document workloads while bringing built-in caching and a SQL-first query language.

Key Features:

• Memory-First Architecture. Each node has a managed cache layer; hot data is served from memory at memcached speeds.
• N1QL (SQL for JSON). A SQL-like query language operating over JSON documents — familiar to RDBMS engineers, with extensions for nested arrays and objects.
• Auto-Sharding via vBuckets. 1024 virtual buckets distributed across nodes; rebalance is online and incremental.
• XDCR. Cross-Data-Center Replication for active/active multi-region deployments.
• Full-Text Search Service. Native FTS index alongside the document store — competitive with Elasticsearch for many workloads.
• Analytics Service. Columnar storage backed by SQL++ for ad-hoc analytical queries on operational data without ETL.
• Eventing & Mobile Sync. Server-side functions on document mutations; Couchbase Lite + Sync Gateway for offline-first mobile apps (the CouchDB heritage).

Couchbase vs. MongoDB:

• Query language. Couchbase — N1QL is SQL-flavored; MongoDB — MQL is JSON / pipeline-flavored. Same semantic power, very different developer feel.
• Caching. Couchbase — memory-first cache built in. MongoDB — no managed cache; pair with Redis.
• Mobile sync. Couchbase — first-class via Couchbase Lite. MongoDB — Realm / Atlas Device Sync.
• Ecosystem & community. MongoDB has a much larger user base and driver ecosystem.

Use Cases:

• Operational applications where SQL fluency in the team matters and N1QL reduces ramp-up.
• Workloads needing both fast cache and durable document storage in one system (avoid Redis + Mongo dual stack).
• Mobile-first applications using Couchbase Lite for offline sync to a server-side Couchbase cluster.
• Multi-region active/active deployments via XDCR.