def create_shard_routing(class_, *pargs, **kargs):
"""This creates the ShardRouting object based on the kargs.
This prunes the routing kargs so as not to interfere with the
actual database method.
Args:
*pargs: Positional arguments
**kargs: Routing key-value params. These are used to determine routing.
There are two mutually exclusive mechanisms to indicate routing.
1. entity_id_map {"entity_id_column": entity_id_value} where entity_id_column
could be the sharding key or a lookup based entity column of this table. This
helps determine the keyspace_ids for the cursor.
2. keyrange - This helps determine the keyrange for the cursor.
Returns:
ShardRouting object and modified kargs
"""
lookup_cursor_method = pargs[0]
routing = db_object.ShardRouting(class_.keyspace)
entity_id_map = None
entity_id_map = kargs.get("entity_id_map", None)
if entity_id_map is None:
kr = None
key_range = kargs.get("keyrange", None)
if isinstance(key_range, keyrange.KeyRange):
kr = key_range
else:
kr = keyrange.KeyRange(key_range)
if kr is not None:
routing.keyrange = kr
# Both entity_id_map and keyrange have been evaluated. Return.
return routing
# entity_id_map is not None
if len(entity_id_map) != 1:
dbexceptions.ProgrammingError("Invalid entity_id_map '%s'" %
entity_id_map)
entity_id_col = entity_id_map.keys()[0]
entity_id = entity_id_map[entity_id_col]
#TODO: the current api means that if a table doesn't have the sharding key column name
# then it cannot pass in sharding key for routing purposes. Will this cause
# extra load on lookup db/cache ? This is cleaner from a design perspective.
if entity_id_col == class_.sharding_key_column_name:
# Routing using sharding key.
routing.sharding_key = entity_id
if not class_.is_sharding_key_valid(routing.sharding_key):
raise dbexceptions.InternalError("Invalid sharding_key %s" %
routing.sharding_key)
else:
# Routing using lookup based entity.
routing.entity_column_name = entity_id_col
routing.entity_id_sharding_key_map = class_.lookup_sharding_key_from_entity_id(
lookup_cursor_method, entity_id_col, entity_id)
return routing
def create_shard_routing(class_, *pargs, **kwargs):
routing = db_object.ShardRouting(class_.keyspace)
routing.shard_name = kwargs.get('shard_name')
if routing.shard_name is None:
dbexceptions.InternalError(
'For custom sharding, shard_name cannot be None.')
if (_is_iterable_container(routing.shard_name) and is_dml):
raise dbexceptions.InternalError(
'Writes are not allowed on multiple shards.')
return routing
def create_shard_routing(class_, *pargs, **kwargs):
routing = db_object.ShardRouting(class_.keyspace)
routing.keyrange = keyrange.KeyRange(
keyrange_constants.NON_PARTIAL_KEYRANGE)
return routing