Middleware

Pgpool-II

Pgpool-II in practice - clustering modes, how load balancing decides where a SELECT goes, watchdog quorum, failover, and the diagnostics.

Read the Pgpool-II guide

Concepts it implements

Connection pooling

Many client connections share a smaller set of server connections, because a database connection is expensive and mostly idle.

Where Pgpool-II sits

How this component relates to the rest of the stack. Items without a link are not covered here yet.

Depends on

Must be present for this to run

PostgreSQL

Deployed with

Commonly run alongside

PostgreSQL

Alternatives

Solves a similar problem differently

Pgpool-II release support

5 supported

Five stable branches are maintained concurrently, mirroring the PostgreSQL major versions they support. All five received a coordinated release on 2026-06-04.

Release	Latest	Released	End of life	Status
`4.7`	`4.7.2`	-	not published	Supported
`4.6`	`4.6.7`	-	not published	Supported
`4.5`	`4.5.12`	-	not published	Supported
`4.4`	`4.4.17`	-	not published	Supported
`4.3`	`4.3.20`	-	not published	Supported

Data as of 2026-10-01 from pgpool.net. Refresh with node scripts/fetch-versions.mjs.