PgCat

What PgCat is

PgCat is a PostgreSQL connection pooler and proxy for Linux and self-hosted deployments. It supports stable transaction and session pooling, and can automatically balance read queries between the primary database and replicas. Health checks identify broken replicas, allowing queries to be redirected to servers that remain available. The project uses Tokio’s asynchronous runtime and a multithreaded design for multicore machines. Operators can inspect pooler statistics through the pgcat and pgbouncer admin databases or a Prometheus HTTP endpoint. Client and PostgreSQL server connections can use SSL/TLS, with MD5 and SCRAM-SHA-256 authentication supported. MD5 authentication passthrough can use auth_query, so cleartext passwords are not needed in the configuration file. Sharding syntax, comment parsing, automatic sharding, and mirroring are experimental; mirroring sends queries to multiple databases for testing or replica prewarning. Transaction mode is on by default, but does not support prepared statements, SET, or advisory locks. Docker deployment is documented, and a container image is published. PgCat is free and open source under the MIT license. The project describes it as stable and reports production use serving hundreds of thousands of queries per second.

Who it suits

PgCat suits teams running PostgreSQL on Linux that want connection pooling, read-query balancing, or automatic failover in a self-hosted deployment. It may also suit operators who need pooler statistics, SSL/TLS connections, and MD5 or SCRAM-SHA-256 authentication.

Limits

The free Open source plan is self-hosted under the MIT license. Transaction mode is enabled by default and does not support prepared statements, SET, or advisory locks; sharding-related features and mirroring are experimental.

Getting started

1. Open the PgCat project website on GitHub
2. Choose a self-hosted Linux deployment
3. Follow the documented Docker deployment route or use the published ghcr.io/postgresml/pgcat:latest image
4. Configure PostgreSQL pooling and connections for your deployment

Verdict

Choose PgCat if you need a free, MIT-licensed PostgreSQL pooler for self-hosted Linux, with pooling, read balancing, and failover. Look elsewhere if your transaction-mode workload depends on prepared statements, SET, or advisory locks, or if you need sharding or mirroring as stable features.