Open-Source Databases · apache

incubator-pegasus

Apache Pegasus is a distributed key-value database designed to balance the speed of Redis with the consistency guarantees of HBase. It uses C++ and RocksDB for persistence, replicates writes across three servers, and automatically handles load balancing across a cluster.

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Source: GitHub — github.com/apache/incubator-pegasus

2.1k

GitHub stars

328

Forks

C++

Primary language

Apache-2.0

License (OSI-approved)

Key facts

Objective fields from the source. Values we can't verify are shown as “Unknown” rather than guessed.

Field	Value
Repository	apache/incubator-pegasus
Owner	apache
Primary language	C++
License	Apache-2.0 — OSI-approved
Stars	2.1k
Forks	328
Open issues	293
Latest release	v2.5.0 (2023-12-11)
Last updated	2026-06-16
Source	https://github.com/apache/incubator-pegasus

What incubator-pegasus is

Pegasus implements the PacificA consensus protocol for strong consistency across replicated partitions, uses hash-based partitioning for horizontal scaling, and employs RocksDB as its underlying storage engine. It provides multi-language client support (Java, C++, Go, Python, Node.js, Scala) and includes features like cold backup, intra-datacenter duplication, and online partition splitting.

Quickstart

Get the incubator-pegasus source

Clone the repository and explore it locally.

terminalbash

1git clone https://github.com/apache/incubator-pegasus.git2cd incubator-pegasus3# follow the project's README for install & configuration

Need it deployed, integrated, or customized instead? DEV.co ships production installs.

Best use cases

Medium-to-large scale distributed caching with consistency requirements

Pegasus fills the gap between Redis (eventual consistency, in-memory) and HBase (strong consistency, Java-heavy). Use when you need sub-second latency with guaranteed single-write replication across multiple nodes.

Multi-datacenter availability with local access optimization

Pegasus's duplication feature enables eventually-consistent replication to remote clusters, allowing services to read/write locally while maintaining distributed redundancy without global synchronization overhead.

Applications requiring fast data migration and automatic rebalancing

Built-in MetaServer handles replica distribution, automatic load balancing, and online partition splitting without downtime—valuable for services that scale dynamically or migrate between infrastructure.

Implementation considerations

Cluster deployment requires MetaServer, ReplicaServers, and a consensus protocol—not a single-binary solution. Operational complexity increases with cluster size.
Three-way replication is mandatory for writes; plan for at least 3 nodes in production. This affects infrastructure cost and network topology decisions.
PacificA protocol membership changes and partition splits are online but require careful orchestration; document runbooks for common operations.
RocksDB is the storage engine; tune compression, block cache, and bloom filters for your workload. Default settings may not match high-throughput or low-latency requirements.
Client libraries exist for multiple languages, but feature parity and maturity may vary (Java, C++, Go are likely more mature than Python or Node.js).

When to avoid it — and what to weigh

Your team is primarily Java-based and invested in HBase ecosystem — Pegasus is C++ native. While Java clients exist, operational experience, tooling, and community depth differ significantly from HBase. Operational overhead may be higher if your DevOps stack assumes JVM deployments.
You require document-oriented or complex query semantics — Pegasus is a key-value store with no native support for complex queries, secondary indexes, or document storage. If your data model is relational or requires ad-hoc aggregations, consider PostgreSQL or MongoDB instead.
You need a managed/fully hosted solution — Pegasus is open-source and requires self-hosted deployment. There is no official commercial SaaS offering. Operational burden (monitoring, backups, upgrades, scaling) falls entirely on your team.
Your project requires enterprise-grade support contracts — Pegasus is incubating under Apache. Community support is available via mailing lists and GitHub issues, but no commercial support agreements or SLAs are advertised in the provided data.

License & commercial use

Licensed under Apache License 2.0, a permissive OSI license. Allows commercial use, modification, and distribution under the same terms. No patent grant or indemnification beyond the license text.

Apache 2.0 permits commercial use without explicit restrictions. However, this is not a commercial product with vendor support. Organizations deploying Pegasus assume operational and security responsibility. No warranty or SLA is provided by the project; commercial usage is at your own risk and cost.

DEV.co evaluation signals

Editorial assessment — not user reviews. Directional, with an explicit confidence level.

Signal	Assessment
Maintenance	Active
Documentation	Adequate
License clarity	Clear
Deployment complexity	High
DEV.co fit	Good
Assessment confidence	High

Security considerations

No security audit, penetration test results, or public CVE history provided. Data is replicated three-way before client acknowledgment (reducing data loss risk). Consensus protocol (PacificA) is peer-reviewed research, but implementation security is Unknown. No mention of encryption at rest, encryption in transit, authentication, authorization, or multi-tenancy isolation in provided data. Requires dedicated security review before handling sensitive data.

Alternatives to consider

Redis Cluster

Simpler single-language ecosystem and operational model, but weaker consistency guarantees (eventual consistency within cluster). Better for latency-critical, eventual-consistency-tolerant workloads.

Apache HBase

Stronger Java ecosystem, mature operational tooling (Hadoop, Spark integration), and column-family semantics. Heavier than Pegasus (JVM overhead) but deeper enterprise adoption and community.

RocksDB (embedded or via RPC wrapper)

Bare-metal storage layer Pegasus uses. If you need only single-node, high-performance KV storage without distribution, RocksDB alone is simpler. Multi-node coordination is your responsibility.

Software development agency

Build on incubator-pegasus with DEV.co software developers

Pegasus excels at bridging Redis-like performance with HBase-like consistency. Assess your consistency requirements, cluster operational readiness, and data model complexity before committing. Consult with DevOps and security teams on deployment, monitoring, and threat modeling.

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incubator-pegasus FAQ

How does Pegasus differ from Redis?

Pegasus uses PacificA for strong consistency (vs. Redis's eventual), is distributed out-of-the-box (vs. Redis Cluster), and persists to disk immediately (vs. Redis's in-memory default). Redis is lower-latency for non-critical data; Pegasus is for consistency-critical workloads.

What is the minimum cluster size for production?

Three ReplicaServers are recommended (matching three-way replication). At least one MetaServer is required for cluster management. Smaller deployments (2 nodes) possible but reduce fault tolerance.

Can I run Pegasus on managed cloud platforms?

Yes, on compute instances (EC2, GCE, Azure VMs). No native managed offering (e.g., AWS DynamoDB equivalent) is provided. You manage provisioning, upgrades, backups, and monitoring.

Is there commercial support available?

Not advertised in the project data. Support is community-driven via GitHub Issues and mailing lists. Organizations may hire consultants or fork for custom support; this is not official.

Work with a software development agency

DEV.co is a software development agency delivering custom software development services to companies building on open source. Our software developers and web developers design, integrate, and ship production systems — spanning web development, APIs, AI, data, and cloud. If incubator-pegasus is part of your open-source databases roadmap, our team can implement, customize, migrate, and maintain it.

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