Method partitions

lib/sqlalchemy/engine/result.py:862–918

Iterate through sub-lists of rows of the size given. Each list will be of the size given, excluding the last list to be yielded, which may have a small number of rows. No empty lists will be yielded. The result object is automatically closed when the iterator

(
        self, size: Optional[int] = None
    )

        return self._next_impl()

    def partitions(
        self, size: Optional[int] = None
    ) -> Iterator[Sequence[Row[Unpack[_Ts]]]]:
        """Iterate through sub-lists of rows of the size given.

        Each list will be of the size given, excluding the last list to
        be yielded, which may have a small number of rows.  No empty
        lists will be yielded.

        The result object is automatically closed when the iterator
        is fully consumed.

        Note that the backend driver will usually buffer the entire result
        ahead of time unless the
        :paramref:`.Connection.execution_options.stream_results` execution
        option is used indicating that the driver should not pre-buffer
        results, if possible.   Not all drivers support this option and
        the option is silently ignored for those who do not.

        When using the ORM, the :meth:`_engine.Result.partitions` method
        is typically more effective from a memory perspective when it is
        combined with use of the
        :ref:`yield_per execution option <orm_queryguide_yield_per>`,
        which instructs both the DBAPI driver to use server side cursors,
        if available, as well as instructs the ORM loading internals to only
        build a certain amount of ORM objects from a result at a time before
        yielding them out.

        .. versionadded:: 1.4

        :param size: indicate the maximum number of rows to be present
         in each list yielded.  If None, makes use of the value set by
         the :meth:`_engine.Result.yield_per`, method, if it were called,
         or the :paramref:`_engine.Connection.execution_options.yield_per`
         execution option, which is equivalent in this regard.  If
         yield_per weren&#x27;t set, it makes use of the
         :meth:`_engine.Result.fetchmany` default, which may be backend
         specific and not well defined.

        :return: iterator of lists

        .. seealso::

            :ref:`engine_stream_results`

            :ref:`orm_queryguide_yield_per` - in the :ref:`queryguide_toplevel`

        """

        getter = self._manyrow_getter

        while True:
            partition = getter(self, size)
            if partition:
                yield partition
            else:
                break