29 lines
1.4 KiB
ReStructuredText
29 lines
1.4 KiB
ReStructuredText
Requests
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========
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The ``start_request`` method of :class:`~pymongo.mongo_client.MongoClient`
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and :class:`~pymongo.mongo_replica_set_client.MongoReplicaSetClient` is now
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**deprecated** and will be removed in PyMongo 3.0.
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PyMongo versions previous to 3.0 support the idea of a *request*: a series of
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operations executed with a single socket. This feature intended to make
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read-your-writes consistency more likely, even with unacknowledged writes.
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(That is, operations with write concern ``w=0``.)
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However, mongos 2.6 doesn't support socket pinning by default, and `mongos 2.8
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doesn't support it at all`_, so requests provide no benefit with sharding.
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In any case, requests are no longer necessary with PyMongo.
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By default, the methods :meth:`~pymongo.collection.Collection.insert`,
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:meth:`~pymongo.collection.Collection.update`,
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:meth:`~pymongo.collection.Collection.save`, and
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:meth:`~pymongo.collection.Collection.remove` block until they receive
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acknowledgment from the server, so ordered execution is already guaranteed. You
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can be certain the next :meth:`~pymongo.collection.Collection.find` or
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:meth:`~pymongo.collection.Collection.count`, for example, is executed on the
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server after the writes complete. This is called "read-your-writes
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consistency." If your application requires this consistency, do not override
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the default write concern with ``w=0``.
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.. _mongos 2.8 doesn't support it at all: https://jira.mongodb.org/browse/SERVER-12273
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