code: def primary_keys(table)
        if self.class.lowercase_schema_reflection
          @connection.primary_keys(table).map do |key|
            key.downcase
          end
        else
          @connection.primary_keys(table)
        end
      end
docs: - begin_db_transaction
  - commit_db_transaction
  - rollback_db_transaction
  - begin_isolated_db_transaction
  - supports_transaction_isolation?
  - write_large_object
  - pk_and_sequence_for
  - primary_key
  - primary_keys