TLDR Connection initiation overhead is killing your webapp — by Eric Worden

What is the proper max_connections for PostgreSQL? — is the wrong question! Use a connection pool, like PgBouncer.

“Will more connections will get me more throughput?” is also wrong.

The right one is

How can my existing set of connections be used efficiently?

Connections carry overhead:

• overhead of initializing each connection
• overhead of maintaining an open connection
• overhead of process concurrency in the OS
• overhead of concurrency in the database

connect-query-disconnect cycle is so slow!

Simple pgbench benchmark with and without pgbouncer (a connection pooler) illustrate connection initiation overhead:

The benchmarks with connection pooling produced eight times more transactions while using less CPU time!

Try okmeter.io — a monitoring solution that will show you everything about Postgresql and PgBouncer operations.