Limit connection numbers with pgbouncer

Question

So I have this pgbouncer config:

[databases]
my_db = host=10.10.10.10
my_db_with_conn_limit = host=10.10.10.10 dbname=my_db pool_size=55

max_client_conn = 300
default_pool_size = 65
reserve_pool_size = 5
reserve_pool_timeout = 1 

And the goal is to limit the number of connections from a specific app - when the db name is database_with_conn_limit, only 55 connections are allowed.

Basically, the apps are identical, but I want one to be limited in connections and the other one grab as many as it wants.

• Is this a correct setup?
• Or should I specify pool_size for my_db, too, giving it all Postgres has minus 55?

Answer 1

You don't have to "specify pool_size for my_db, too".

But your config won't limit the number of connections though. You need to limit max_db_connections for that like here:

[databases]
my_db = host=10.10.10.10
my_db_with_conn_limit = host=10.10.10.10 dbname=my_db pool_size=55  max_db_connections=55

Otherwise you limit the number of sessions in pool, but not the number of connections...

You can also just set different limits per database+user pair instead (which I believe is more common practice).