Homebrew install specific version of formula?

Question

How do I install a specific version of a formula in homebrew? For example, postgresql-8.4.4 instead of the latest 9.0.

Answer 1

it could be done very easy for last version of brew.

brew tap homebrew/versions
brew install subversion17 # for svn 1.7 branch instead of last available
brew install postgresql8  # for postgresql 8 (which you ask)