Increasing max connections under OS X - sociam/indx GitHub Wiki

To increase postgresql's max_connections, you must first increase the system's shared memory parameters.

Create a file called /etc/sysctl.conf and put in the following:

kern.sysv.shmmax=40960000
kern.sysv.shmmin=1
kern.sysv.shmmni=32
kern.sysv.shmseg=8
kern.sysv.shmall=4096

Then reboot.

Then edit your postgresql.conf and change max_connections to 100 (or whatever you want the value to be).

If you are using Postgres.app, then the file is located at:

~/Library/Application\ Support/Postgres/var/postgresql.conf