Everyone into the Pool

A detailed comparison of five PostgreSQL connection poolers — Pgpool-II, PgBouncer, Amazon RDS Proxy, PgCat, and PgDog — examining how each handles session state (SET commands, prepared statements, advisory locks, LISTEN/NOTIFY) under transaction pooling. Pgpool-II (since 2003) only supports session pooling and is being superseded by dedicated failover tools. PgBouncer (since 2007, now 1.26.0) remains the default lightweight choice, tracking more server parameters since PostgreSQL 18 closed the long-standing search_path leak. RDS Proxy pins sessions aggressively on any SET statement, which can silently defeat pooling for ORMs like Rails. PgCat, written in Rust, is effectively abandoned since 2025. PgDog, built by the same author as PgCat, parses SQL with PostgreSQL's own parser to replay session state faithfully and adds sharding, read/write splitting, and two-phase commit, though it remains a fast-moving 0.1.x project under AGPL-3.0. Concrete recommendations are given per use case.

Source: https://postgr.es/p/9w_. 8 Sync News only summarizes and links out; content copyright belongs to the authors and original sources.