Rake Task to kill postgres test and development database connections

gistfile1.md

  desc "Kill test and development postgres database connections"
  task :pg_terminate => :environment do

    dbs = []
    dbs << ActiveRecord::Base.configurations["development"]["database"]
    dbs << ActiveRecord::Base.configurations["test"]["database"]
    db_names = "#{dbs.map{|name| "'#{name}'"}.join(", ")}"

    terminated = false
    last_error = ""
    ["procpid", "pid"].each do |process_id_field|
      puts ">> Attempting to pg_terminate with #{process_id_field}"
      begin
        results = ActiveRecord::Base.connection.execute("
          SELECT pg_terminate_backend(#{process_id_field})
          FROM pg_stat_activity
          WHERE #{process_id_field} <> pg_backend_pid()
          AND datname IN(#{db_names})
        ")
        terminated = true
      rescue => e
        last_error = e.to_s
      end
      break if terminated
    end
    if terminated
      puts ">> #{db_names} connections terminated"
    else
      puts ">> Unable to terminate postgres connections"
      puts last_error
    end
  end