$ which psql
$ sudo -u postgres createuser -s $USER
$ createdb -U $USER --locale=en_US.utf-8 -E utf-8 -O $USER newdb -T template0
$ dropdb development_database_name
$ createdb development_database_name
$ brew update
$ brew install postgresql
# create symlink
$ ln -sf /usr/local/Cellar/postgresql/9.5.5/homebrew.mxcl.postgresql.plist ~/Library/LaunchAgents/homebrew.mxcl.postgresql.plist
# start the service
$ launchctl load -w ~/Library/LaunchAgents/homebrew.mxcl.postgresql.plist
# create database
$ createdb mydb