class ActiveRecord::ConnectionAdapters::SchemaCache

def data_source_exists?(pool, name)
  return if ignored_table?(name)
  if @data_sources.empty?
    tables_to_cache(pool).each do |source|
      @data_sources[source] = true
    end
  end
  return @data_sources[name] if @data_sources.key? name
  @data_sources[deep_deduplicate(name)] = pool.with_connection do |connection|
    connection.data_source_exists?(name)
  end
end