Current File : //proc/self/root/opt/alt/python27/lib64/python2.7/site-packages/sqlalchemy/ext/horizontal_shard.pyc
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s Horizontal sharding support.
Defines a rudimental 'horizontal sharding' system which allows a Session to
distribute queries and persistence operations across multiple databases.
For a usage example, see the :ref:`examples_sharding` example included in
the source distribution.
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all subsequent operations with the returned query will
be against the single shard regardless of other state.
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c K s� | d k r. t t | � j | | d | | �S| j j | � } | rX | j | � } n xN | j | | � D]: } t t | � j | | d | | �} | d k rk | Sqk Wd Sd S( s� override the default Query._identity_lookup method so that we
search for a given non-token primary key identity across all
possible identity tokens (e.g. shard ids).
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R t primary_key_identityR t lazy_loaded_fromt kwR R t obj( ( sR /opt/alt/python27/lib64/python2.7/site-packages/sqlalchemy/ext/horizontal_shard.pyR/ Y s c sX � � f d � } | d k r9 � j d k r9 � j } n t t � � j | | d | �S( s� Override the default Query._get_impl() method so that we emit
a query to the DB for each possible identity token, if we don't
have one already.
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__module__R R R# R. R R/ R; ( ( ( sR /opt/alt/python27/lib64/python2.7/site-packages/sqlalchemy/ext/horizontal_shard.pyR s R, c B s, e Z d Z d Z d � Z e d � � Z RS( s� A value object that represents multiple :class:`.ResultProxy` objects.
This is used by the :meth:`.ShardedQuery._execute_crud` hook to return
an object that takes the place of the single :class:`.ResultProxy`.
Attribute include ``result_proxies``, which is a sequence of the
actual :class:`.ResultProxy` objects, as well as ``aggregate_rowcount``
or ``rowcount``, which is the sum of all the individual rowcount values.
.. versionadded:: 1.3
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| | | � q_ Wn d S( s Construct a ShardedSession.
:param shard_chooser: A callable which, passed a Mapper, a mapped
instance, and possibly a SQL clause, returns a shard ID. This id
may be based off of the attributes present within the object, or on
some round-robin scheme. If the scheme is based on a selection, it
should set whatever state on the instance to mark it in the future as
participating in that shard.
:param id_chooser: A callable, passed a query and a tuple of identity
values, which should return a list of shard ids where the ID might
reside. The databases will be queried in the order of this listing.
:param query_chooser: For a given Query, returns the list of shard_ids
where the query should be issued. Results from all shards returned
will be combined together into a single listing.
:param shards: A dictionary of string shard names
to :class:`~sqlalchemy.engine.Engine` objects.
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