mhenrixon | Killing db connections softly with rake tasks

I literally couldn't decide what pun to use here: drop it like it's hot, killing me softly, or something about waiting for the (data)base to drop. Anyway, I frequently, and in every project, have this need, so this time, I will post it somewhere I won't forget it.

When I need to search for it next time, I will have solid search functionality on my blog!

# frozen_string_literal: true

namespace :db do
  desc "Terminate all connections to the development databases"
  task terminate_connections: :environment do
    if Rails.env.local?
      database_name = ActiveRecord::Base.connection_db_config.database
      ActiveRecord::Base.connection.execute(<<~SQL.squish)
        SELECT pg_terminate_backend(pg_stat_activity.pid)
          FROM pg_stat_activity
         WHERE pg_stat_activity.datname = '#{database_name}'
           AND pid <> pg_backend_pid();
      SQL
    end
  end
end

Rake::Task["db:drop"].enhance(["db:terminate_connections"])

The important thing here is to enhance it because that ensures the order is correct. If you instead open the db:drop task and invoke the task there, it will fail because that runs after.