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Slumber DB

maintenance

by Richard Hightower · since 2014 · also known as SlumberDB

Small Java key/value API for JSON objects over LevelDB, RocksDB, LMDB or MySQL; abandoned in 2014.

key-valuedocumentembedded libraryopen source (permissive)legacy
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maintenance. No commits since September 2014, along with the rest of the Boon project; effectively unmaintained. Use MapDB, Chronicle Map or RocksDB's Java API.

Overview

Slumber DB was Richard Hightower's companion to the Boon JSON library: a typed Java key/value store that serializes objects with Boon (JSON) or Kryo (binary) and persists them to a pluggable backend such as LevelDB, RocksDB, LMDB or MySQL. It was aimed at REST and WebSocket services that just need to save and load objects by key, with batch reads and writes, deletes and key search, and deliberately avoided data-grid features. The project stopped in 2014, so it only matters if you are maintaining code that already uses it.

Embedded / in-processSession store

Strengths & trade-offs

Strengths

  • +Thin, typed Java API over several proven storage engines
  • +Fast JSON (Boon) and binary (Kryo) serialization built in
  • +Swap LevelDB, RocksDB, LMDB or MySQL backends without changing application code

Trade-offs

  • −Abandoned since 2014 with outdated dependencies
  • −Key/value only: no queries on fields, secondary indexes or multi-key transactions
  • −Tiny user base and sparse documentation

Great for

  • +Maintaining older Boon-based Java services
  • +Reference design for a pluggable JVM key/value facade

Think twice for

  • −New Java projects
  • −Querying JSON documents by field

Capabilities

Native or official first-party support · 2 of 25 tracked

✓JSON
✓Durable persistence
–Transactions
–Joins
–Secondary indexes
–Full-text search
–Vector search
–Geospatial
–Change data capture
–Triggers
–Stored procedures
–Materialized views
–TTL / expiry
–Pub/Sub
–Columnar storage
–In-memory
–Compression
–Encryption at rest
–Role-based access
–Time travel
–Branching
–Online schema changes
–Streaming ingest
–Offline sync
–Runs in WebAssembly

Scale & consistency

Comfortable data size
Small · ≤ 100 GB
Horizontal scaling
None
Multi-region
No
Transactions
Limited ACID
Consistency
Strong
Schema
Schemaless
Architecture
Embedded
Query languages
Java API

Deployment

Self-hosted Vendor-managed cloud Serverless Embedded Edge Kubernetes operator

Ecosystem

client languagesJava

Alternatives to Slumber DB

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MapDBKey-Value7.6

Embedded Java database exposing concurrent Maps, Sets and Queues backed by disk or off-heap memory.

slumber-db vs mapdb →
Chronicle MapKey-Value8.7

Off-heap, memory-mapped key-value store for Java with microsecond latency and cross-process sharing.

slumber-db vs chronicle-map →
RocksDBKey-Value48.2

Meta's embeddable LSM-tree key-value engine, the storage layer under dozens of databases.

slumber-db vs rocksdb →
LMDBKey-Value39.7

Tiny memory-mapped B+tree with ACID transactions and lock-free readers; reached 1.0 in 2026.

slumber-db vs lmdb →
XodusKey-Value6.8

JetBrains' embedded transactional Java/Kotlin store behind YouTrack; in sunset in favour of YouTrackDB.

slumber-db vs xodus →
Dexie.jsDocument25.8

The most popular IndexedDB wrapper, with live queries and an optional Dexie Cloud sync service.

slumber-db vs dexie →

Slumber DB FAQ

What is Slumber DB?

Slumber DB is a key-value database by Richard Hightower, first released in 2014. Slumber DB was Richard Hightower's companion to the Boon JSON library: a typed Java key/value store that serializes objects with Boon (JSON) or Kryo (binary) and persists them to a pluggable backend such as LevelDB, RocksDB, LMDB or MySQL. It was aimed at REST and WebSocket services that just need to save and load objects by key, with batch reads and writes, deletes and key search, and deliberately avoided data-grid features. The project stopped in 2014, so it only matters if you are maintaining code that already uses it.

Is Slumber DB open source?

Yes. Slumber DB is open source. License: Apache License 2.0.

Does Slumber DB support ACID transactions?

Partly. Slumber DB offers limited ACID guarantees (for example, single-record or single-partition transactions), with strong consistency.

Does Slumber DB scale horizontally?

Slumber DB does not scale horizontally; it runs on a single node, so you scale it up rather than out. It is comfortable at small scale (≤ 100 GB).

How can I run Slumber DB?

You can self-host it and embed it in your application.

What is Slumber DB best for?

Slumber DB is a strong fit for maintaining older Boon-based Java services and reference design for a pluggable JVM key/value facade. Think twice for new Java projects.

What are the best alternatives to Slumber DB?

Common alternatives to Slumber DB include MapDB, Chronicle Map, RocksDB, LMDB and Xodus. The right choice depends on your workload, scale and hosting; WhichDB's smart match ranks them against your requirements.

Is Slumber DB still maintained?

Slumber DB is in maintenance mode. No commits since September 2014, along with the rest of the Boon project; effectively unmaintained. Use MapDB, Chronicle Map or RocksDB's Java API.

How popular is Slumber DB?

Slumber DB ranks #612 of 844 databases on the WhichDB Score (0.8/100), and #111 among key-value databases. The score combines public adoption signals such as package downloads, GitHub activity, job posts and developer discussion.