# apache/bookkeeper

Apache BookKeeper - a scalable, fault tolerant and low latency storage service optimized for append-only workloads

Repository: https://github.com/apache/bookkeeper
Canonical: https://ross.abutalabs.com/products/bookkeeper
Homepage: https://bookkeeper.apache.org/
Language: Java
License: Apache-2.0
License Family: permissive
Topics: bookkeeper, big-data, apache, distributed-log, distributed-systems, wal
Last push: 2026-08-21T03:51:07+00:00

## Health v2 (maintenance only)
Score: 89/100 (v2, computed 2026-09-03T02:20:16.233290+00:00)
- activity 98, release rhythm 71, longevity 100
- inputs: {"age_days": 5628, "days_push": 12, "days_rel": 37, "gap_med": 94.0, "n_releases_24m": 5}
- flags: none
- formula: round(0.45*activity + 0.35*rhythm + 0.20*longevity); archived -> min(score, 10)

## Adoption (not part of the score)
Stars 2009, forks 973 (observed 2026-08-28T04:06:04.965171+00:00)

## What it is
Apache BookKeeper is a scalable, fault-tolerant, low-latency distributed storage service optimized for append-only workloads, offering replication, durability, and strong consistency. It serves as the underlying log storage for systems like Apache Pulsar, HDFS NameNode WAL, and Pravega.

## Use cases
- store write-ahead logs for distributed systems like HDFS NameNode
- persist message streams for a pub-sub messaging system
- store offsets and cursors for message consumers
- replicate state machine snapshots and blobs
- build a scalable distributed log with strong consistency guarantees

## When to choose
- you need durable, replicated append-only log storage with low latency
- you are running Apache Pulsar or Pravega and need its storage layer
- you need a write-ahead log for a distributed database or state machine

## When to avoid
- you need general-purpose SQL queries or rich secondary indexes
- your workload is read-heavy with random access patterns rather than append-only
- you want a simple single-node embedded database

## Facets
- artifact type: service
- maturity: stable
- function: database, message-queue, logging, streaming
- domain: databases, microservices, big-data
- platform: jvm, self-hosted
- tags: append-only-storage, write-ahead-logging, replication, distributed-log, apache, pulsar-storage, low-latency, messaging, linux, docker

## Member repositories
- apache/bookkeeper (main) score 89

## Provenance
- Observed fields: from GitHub, fetched 2026-08-28T04:06:04.965171+00:00.
- Health v2: computed from the inputs above; adoption is never an input.
- Inferred fields (summary, facets, guidance): AI-extracted, prompt v1, taxonomy v1, on 2026-08-30T03:01:15.481577+00:00, confidence not recorded.
  - readme: https://github.com/apache/bookkeeper (fetched 2026-08-28T04:06:04.965171+00:00, sha fce67da2aa8c)
  - homepage: https://bookkeeper.apache.org/ (fetched 2026-08-29T10:41:15.225760+00:00, sha 75a7401a2c45)
  - site_page: https://bookkeeper.apache.org/docs/overview (fetched 2026-08-29T10:41:15.229181+00:00, sha 26dd73c30a41)
  - site_page: https://bookkeeper.apache.org/docs/next/overview (fetched 2026-08-29T10:41:15.232943+00:00, sha 0396d89c82c2)
  - site_page: https://bookkeeper.apache.org/docs/4.16.7/overview (fetched 2026-08-29T10:41:15.234514+00:00, sha 1e8d3c11127e)
  - site_page: https://bookkeeper.apache.org/docs/4.15.5/overview (fetched 2026-08-29T10:41:15.236022+00:00, sha 0b5381274c03)
  - site_page: https://bookkeeper.apache.org/docs/4.14.8/overview (fetched 2026-08-29T10:41:15.237602+00:00, sha df8c83091719)
  - site_page: https://bookkeeper.apache.org/docs/4.13.0/overview (fetched 2026-08-29T10:41:15.239342+00:00, sha 0c4d0feef9cd)
  - site_page: https://bookkeeper.apache.org/docs/4.12.1/overview (fetched 2026-08-29T10:41:15.241773+00:00, sha 0cab16ed2de9)
  - site_page: https://bookkeeper.apache.org/community/releases (fetched 2026-08-29T10:41:15.231242+00:00, sha 8bbf0f3a503e)
- Data as of 2026-08-30T08:39:29.467469+00:00.