Class set_shard_id

lib/sqlalchemy/ext/horizontal_shard.py:376–423

a loader option for statements to apply a specific shard id to the primary query as well as for additional relationship and column loaders. The :class:`_horizontal.set_shard_id` option may be applied using the :meth:`_sql.Executable.options` method of any executable statement::

class set_shard_id(ORMOption):
    """a loader option for statements to apply a specific shard id to the
    primary query as well as for additional relationship and column
    loaders.

    The :class:`_horizontal.set_shard_id` option may be applied using
    the :meth:`_sql.Executable.options` method of any executable statement::

        stmt = (
            select(MyObject)
            .where(MyObject.name == "some name")
            .options(set_shard_id("shard1"))
        )

    Above, the statement when invoked will limit to the "shard1" shard
    identifier for the primary query as well as for all relationship and
    column loading strategies, including eager loaders such as
    :func:`_orm.selectinload`, deferred column loaders like :func:`_orm.defer`,
    and the lazy relationship loader :func:`_orm.lazyload`.

    In this way, the :class:`_horizontal.set_shard_id` option has much wider
    scope than using the "shard_id" argument within the
    :paramref:`_orm.Session.execute.bind_arguments` dictionary.


    .. versionadded:: 2.0.0

    """

    __slots__ = ("shard_id", "propagate_to_loaders")

    def __init__(
        self, shard_id: ShardIdentifier, propagate_to_loaders: bool = True
    ):
        """Construct a :class:`_horizontal.set_shard_id` option.

        :param shard_id: shard identifier
        :param propagate_to_loaders: if left at its default of ``True``, the
         shard option will take place for lazy loaders such as
         :func:`_orm.lazyload` and :func:`_orm.defer`; if False, the option
         will not be propagated to loaded objects. Note that :func:`_orm.defer`
         always limits to the shard_id of the parent row in any case, so the
         parameter only has a net effect on the behavior of the
         :func:`_orm.lazyload` strategy.

        """
        self.shard_id = shard_id
        self.propagate_to_loaders = propagate_to_loaders


def execute_and_instances(