I installed Postgresql 9.4.0 installed on my Mac (10.10.1/Yosemite) using homebrew. It does not work.
I have created the softlink to /usr/local/opt/postgresql/homebr
I recently had a problem which began when I upgraded some brew updates / upgrades, mainly python versions etc. What worked for me.
brew uninstall postgres
brew install postgresql@9.5
echo 'export PATH="/usr/local/opt/postgresql@9.5/bin:$PATH"' > ~/.zshrc
# you may need > ~/.bashrc if you use bash
I needed pg_dump, pg_restore etc so to get that working I did
brew install libpq
Start the service
brew services start postgresql@9.5
From here I would have expected everything to work but still all rails db commands were giving error that server was not running. This final bit was the missing piece of the puzzle which finally solved it for me.
gem uninstall pg
gem install pg -v 0.20.0 # which was set in Gemfile
# could also just probably do bundle install instead.