def _create_collection_iterator(collection_name, query):
"""Creates an iterator that returns collections and queries that can then
be used to perform multishard operations:
for collection, query in _create_collection_iterator(...):
for doc in collection.find(query):
yield doc
This does all the hardwork of figuring out what collections to query and how
to adjust the query to account for any shards that are currently moving.
"""
realm = _get_realm_for_collection(collection_name)
shard_field = realm['shard_field']
shard_key = _get_query_target(collection_name, query)
if shard_key:
location = _get_location_for_shard(realm, shard_key)
locations = {location.location: location}
else:
locations = _get_all_locations_for_realm(realm)
for location, location_meta in locations.iteritems():
cluster_name, database_name = location.split('/')
connection = get_connection(cluster_name)
collection = connection[database_name][collection_name]
if location_meta.excludes:
if len(location_meta.excludes) == 1:
query = {'$and': [
query, {shard_field: {'$ne': location_meta.excludes[0]}}]}
else:
raise Exception('Multiple shards in transit. Aborting')
yield collection, query
if location_meta.excludes:
query = query['$and'][0]
def _get_collection_for_targetted_upsert(
collection_name, query, update, with_options={}):
shard_key = _get_query_target(collection_name, update)
if not shard_key:
shard_key = _get_query_target(collection_name, update['$set'])
realm = _get_realm_for_collection(collection_name)
location = _get_location_for_shard(realm, shard_key)
cluster_name, database_name = parse_location(location.location)
connection = get_connection(cluster_name)
collection = connection[database_name][collection_name]
if with_options:
collection = collection.with_options(with_options)
return collection
def _get_collection_for_targetted_upsert(collection_name,
query,
update,
with_options={}):
shard_key = _get_query_target(collection_name, update)
if not shard_key:
shard_key = _get_query_target(collection_name, update['$set'])
realm = _get_realm_for_collection(collection_name)
location = _get_location_for_shard(realm, shard_key)
cluster_name, database_name = parse_location(location.location)
connection = get_connection(cluster_name)
collection = connection[database_name][collection_name]
if with_options:
collection = collection.with_options(with_options)
return collection
def _get_collection_from_location_string(location, collection_name):
server_addr, database_name = location.split('/')
connection = get_connection(server_addr)
return connection[database_name][collection_name]
def _get_collection_from_location_string(location, collection_name):
server_addr, database_name = parse_location(location)
connection = get_connection(server_addr)
return connection[database_name][collection_name]