How to do it…

Each database is completely identified by its connection string. PgBouncer will read this information from its configuration file. The steps to be done are as follows:

1. All you need to do is to set up PgBouncer as you did in the previous recipe, replacing the databases section of pgbouncer.ini with the following:

[databases] 
myfirstdb = port=5432 host=localhost 
anotherdb = port=5437 host=localhost 
sparedb = port=5435 host=localhost

1. Once you have started PgBouncer, you can connect to the first database:

$ psql -p 6432 -h 127.0.0.1 -U postgres myfirstdb
psql (9.6.1)
Type "help" for help.

myfirstdb=# show port;
port 
------
5432
(1 row)

myfirstdb=# show server_version;
server_version 
----------------
10.1
(1 row)

1. Now you can connect to the anotherdb database as if it were on the same server:

myfirstdb=# \c anotherdb
psql (10.1, server 9.6.5)
You are now connected to database "anotherdb" as user "postgres".

1. The server's greeting message suggests that we have landed on a different server, so we check the port and version:

anotherdb=# show port;
 port 
------
  5437
(1 row)

anotherdb=# show server_version;
server_version 
----------------
     9.5.5
(1 row)