HeliosProxy vs PgCat

HeliosProxy is a self-hosted, programmable PostgreSQL data-plane for routing connections, handling failover, replaying traffic, and supporting database upgrades. It provides session, transaction, and statement pooling, with multiplexing up to 100:1. Routing can account for replica lag, workload type, and failing backends through circuit breaking. Cache options include local memory, Redis-backed storage, and semantic tiers, with invalidation when writes occur. Transaction Replay can move sessions to a new primary and optionally replay reads or transactions when conditions permit, although prepared statements, temporary tables, open cursors, advisory locks, and extended-protocol SET statements are not restored. A WebAssembly plugin runtime offers five hook points, Ed25519 verification, and OCI distribution. The admin console includes topology, plugin, chaos, shadow-execution, and traffic-replay panels. Authentication supports JWT, OAuth 2.0, LDAP, and API keys. HeliosProxy works with PostgreSQL 12+ and compatible databases, and deployment documentation covers Docker, Kubernetes, and standalone setups. It is open source under Apache 2.0 and costs nothing.

PgCat is a free, open-source PostgreSQL pooler and proxy for self-hosted Linux deployments. Its stable features include transaction and session pooling. Read queries can be balanced across replicas and the primary, while health checks detect broken replicas and redirect queries to remaining servers. PgCat uses Tokio’s asynchronous runtime and a multithreaded design for multicore machines. Operators can view 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 passthrough can use auth_query so cleartext passwords need not be stored in the configuration file. Docker deployment is documented, and a container image is published. Sharding syntax, comment parsing, automatic sharding, and mirroring are experimental. Transaction mode is enabled by default and does not support prepared statements, SET, or advisory locks. The project describes PgCat as stable and says it serves high query volumes in production. It is licensed under MIT.