PgDog

PgDog is an open-source PostgreSQL proxy that combines connection pooling, load balancing, and sharding in a single executable, deployable anywhere. It acts as a drop-in proxy so applications can connect through one endpoint without code changes, sharing a limited number of database connections across many clients while preserving session state features like SET commands, advisory locks, and LISTEN/NOTIFY.

Its connection pooler supports real transaction mode with multi-threaded, async operation and prepared statement compatibility across client drivers. The load balancer distributes reads across replicas with health checks, replication lag detection, failover detection, and read/write splitting using an internal Postgres SQL parser. The sharding layer routes queries by sharding key, supports scatter/gather for queries without one, cross-shard transactions via two-phase commit, replicated tables, automatic big integer primary keys, and cross-shard DDL compatible with migration tools such as Alembic and ActiveRecord.

PgDog is aimed at teams running PostgreSQL who need horizontal scaling, connection management, or distributed database capabilities. It is open source with an Enterprise offering available; specific packaging details such as free plans, trials, or seat-based pricing are not stated on these pages.