Pgpool-II
Pgpool-II is free, self-hosted middleware that sits between PostgreSQL servers and database clients, relaying PostgreSQL protocol messages transparently.
What Pgpool-II is
Pgpool-II is free, self-hosted middleware that sits between PostgreSQL servers and database clients, relaying PostgreSQL protocol messages transparently. It reuses server connections with matching properties to reduce connection overhead and improve throughput. For replicated databases, it can distribute SELECT queries across servers. High-availability features include automatic failover, Watchdog, quorum, and split-brain prevention; other capabilities include online recovery, connection limiting, replication, and an in-memory query cache. Pgpool-II is available in binary and source formats, with RPM packages for Red Hat Enterprise Linux and compatible distributions. Debian and Ubuntu users are directed to packages from the PostgreSQL community. Authentication options include trust, clear-text password, MD5, SCRAM-SHA-256, certificate, PAM, and LDAP; GSSAPI is not supported. SSL can protect frontend and backend communications when enabled, but it is off by default and requires OpenSSL support. Community help is available through mailing lists and GitHub Issues, with commercial support offered by SRA OSS K.K.
Good
- Free software with no usage fee.
- Pools PostgreSQL server connections.
- Distributes SELECT queries across replicated servers.
- Includes automatic failover and split-brain prevention.
- Supports several authentication methods, including SCRAM-SHA-256.
Watch out
- GSSAPI authentication is not supported.
- SSL is off by default and requires OpenSSL support.
- Unsupported major releases lack formal binary packages.
- No bug bounty program is offered.
Who it suits
Pgpool-II suits PostgreSQL administrators who need self-hosted connection pooling, query distribution, or failover capabilities. It also fits teams comfortable configuring and maintaining middleware themselves.
Verdict
Pgpool-II provides PostgreSQL middleware functions at no license cost, including pooling, load balancing, and high availability. SSL setup and release support status are important considerations for administrators.
Plans and prices
From Pgpool-II's own pricing page, checked 1 Oct 2026.
| Plan | Price | What it gives you |
|---|---|---|
| Pgpool-II | Free | open-source software · self-hosted middleware |
The facts
Each one read from Pgpool-II's own pages, with the date it was checked.
What it does
- Additional features
- Additional features include in-memory query cache, online recovery, connection limiting, Watchdog, and replication.checked 1 Oct 2026
- APT packages
- Users of Debian or Ubuntu are directed to packages provided by the PostgreSQL community.checked 1 Oct 2026
- Authentication
- Supported authentication methods include trust, clear-text password, MD5, SCRAM-SHA-256, certificate, PAM, and LDAP; GSSAPI is not supported.checked 1 Oct 2026
- Connection pooling
- It reuses PostgreSQL server connections with matching properties to reduce connection overhead and improve throughput.checked 1 Oct 2026
- Distribution
- Pgpool-II is available as binary and source formats; the project provides RPM packages for Red Hat Enterprise Linux and compatible distributions.checked 1 Oct 2026
- Documentation
- Official documentation is available in English and Japanese, with tutorials for basic configuration, Watchdog, AWS, and Aurora.checked 1 Oct 2026
- High availability
- It provides automatic failover, Watchdog for Pgpool-II high availability, quorum, and split-brain prevention.checked 1 Oct 2026
- License
- The license permits use, copying, modification, and distribution of the software and documentation for any purpose without a fee.checked 1 Oct 2026
- Load balancing
- For replicated databases, it distributes SELECT queries across servers to reduce load and improve throughput.checked 1 Oct 2026
- Purpose
- Pgpool-II is middleware between PostgreSQL servers and database clients that relays PostgreSQL protocol messages transparently.checked 1 Oct 2026
- Release support
- The project aims to fully support each major release for five years; unsupported releases receive only possible best-effort critical fixes and no formal binary packages.checked 1 Oct 2026
- Security reporting
- The community asks vulnerability reporters to email the project leader privately and does not offer bug bounties.checked 1 Oct 2026
- SSL
- When enabled, SSL protects both frontend and backend communications, but it is off by default and requires OpenSSL support.checked 1 Oct 2026
- Support
- Community support is provided through mailing lists and GitHub Issues, while SRA OSS K.K. offers commercial technical support, consulting, and system integration.checked 1 Oct 2026
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