Reseed database in Rails without dropping it. Originally posted at https://shime.sh/til/faster-database-resets-in-rails

reseed.rake

namespace :db do
  desc 'Clears the database and then seeds it'
  task reseed: :environment do 
    Rake::Task["db:truncate"].invoke
    Rake::Task["db:seed"].invoke
  end

  desc 'Clears the database'
  task truncate: :environment do 
    puts "Truncating database"
    ActiveRecord::Base.connection.tables.reject {|t| t =~ /internal|schema_migrations/}.map do |table|
      putc "."
      ActiveRecord::Base.connection.execute("TRUNCATE TABLE #{table} RESTART IDENTITY CASCADE")
    end
    puts
  end
end