memory_table_tests.rb

namespace :db do
  namespace :schema do
    task :load => :alias_create_table
    task :alias_create_table do
      # WTF!
      if /_test$/ === ActiveRecord::Base.connection.instance_variable_get('@connection_options')[3]
        max_heap_table_size = 180 # Mb
        ActiveRecord::Base.connection.execute("SET max_heap_table_size = #{max_heap_table_size} * 1024 * 1024")

        module ActiveRecord::ConnectionAdapters::SchemaStatements
          def create_table_with_memory_engine(table_name, options = {}, &block)
            begin
              new_options = options.merge(:options => 'ENGINE=MEMORY')
              create_table_without_memory_engine(table_name, new_options, &block)
            rescue
              # Oops, try again
              create_table_without_memory_engine(table_name, options, &block)
            end
          end
          alias_method_chain :create_table, :memory_engine
        end

      end
      
    end
  end
end