def _undo_add_shard_mapping(shard_mapping_id, table_name, column_name,
range_check=False, update_only=False):
"""Add a table to a shard mapping.
:param shard_mapping_id: The shard mapping id to which the input
table is attached.
:param table_name: The table being sharded.
:param column_name: The column whose value is used in the sharding
scheme being applied
:param range_check: Indicates if range check should be turned on for
this table.
:param update_only: Only update the state store and skip adding range checks.
:return: True if the the table was successfully added.
False otherwise.
"""
if range_check and not update_only:
sharding_defn = ShardMapping.fetch_shard_mapping_defn(shard_mapping_id)
if sharding_defn:
_, sharding_type, global_group_id = sharding_defn
SHARD_METADATA_VERIFIER.drop_shard_range_trigger(
global_group_id,
sharding_type,
table_name,
column_name
)
def _undo_add_shard_mapping(shard_mapping_id,
table_name,
column_name,
range_check=False,
update_only=False):
"""Add a table to a shard mapping.
:param shard_mapping_id: The shard mapping id to which the input
table is attached.
:param table_name: The table being sharded.
:param column_name: The column whose value is used in the sharding
scheme being applied
:param range_check: Indicates if range check should be turned on for
this table.
:param update_only: Only update the state store and skip adding range checks.
:return: True if the the table was successfully added.
False otherwise.
"""
if range_check and not update_only:
sharding_defn = ShardMapping.fetch_shard_mapping_defn(shard_mapping_id)
if sharding_defn:
_, sharding_type, global_group_id = sharding_defn
SHARD_METADATA_VERIFIER.drop_shard_range_trigger(
global_group_id, sharding_type, table_name, column_name)
def verify_and_fetch_shard(shard_id):
"""Find out if the shard_id exists and return the sharding specification for
it. If it does not exist throw an exception.
:param shard_id: The ID for the shard whose specification needs to be
fetched.
:return: The sharding specification class representing the shard ID.
:raises: ShardingError if the shard ID is not found.
"""
#Here the underlying sharding specification might be a RANGE
#or a HASH. The type of sharding specification is obtained from the
#shard mapping.
range_sharding_spec = RangeShardingSpecification.fetch(shard_id)
if range_sharding_spec is None:
raise _errors.ShardingError(SHARD_NOT_FOUND % (shard_id, ))
#Fetch the shard mappings and use them to find the type of sharding
#scheme.
shard_mappings = ShardMapping.fetch_by_id(
range_sharding_spec.shard_mapping_id
)
if shard_mappings is None:
raise _errors.ShardingError(
SHARD_MAPPING_NOT_FOUND % (
range_sharding_spec.shard_mapping_id,
)
)
#Fetch the shard mapping definition. There is only one shard mapping
#definition associated with all of the shard mappings.
shard_mapping_defn = ShardMapping.fetch_shard_mapping_defn(
range_sharding_spec.shard_mapping_id
)
if shard_mapping_defn is None:
raise _errors.ShardingError(
SHARD_MAPPING_DEFN_NOT_FOUND % (
range_sharding_spec.shard_mapping_id,
)
)
shard = Shards.fetch(shard_id)
if shard is None:
raise _errors.ShardingError(SHARD_NOT_FOUND % (shard_id, ))
#Both of the shard_mappings retrieved will be of the same sharding
#type. Hence it is safe to use one of them to retireve the sharding type.
if shard_mappings[0].type_name == "HASH":
return HashShardingSpecification.fetch(shard_id), \
shard, shard_mappings, shard_mapping_defn
else:
return range_sharding_spec, shard, shard_mappings, shard_mapping_defn
def verify_and_fetch_shard(shard_id):
"""Find out if the shard_id exists and return the sharding specification for
it. If it does not exist throw an exception.
:param shard_id: The ID for the shard whose specification needs to be
fetched.
:return: The sharding specification class representing the shard ID.
:raises: ShardingError if the shard ID is not found.
"""
#Here the underlying sharding specification might be a RANGE
#or a HASH. The type of sharding specification is obtained from the
#shard mapping.
range_sharding_spec = RangeShardingSpecification.fetch(shard_id)
if range_sharding_spec is None:
raise _errors.ShardingError(SHARD_NOT_FOUND % (shard_id, ))
#Fetch the shard mappings and use them to find the type of sharding
#scheme.
shard_mappings = ShardMapping.fetch_by_id(
range_sharding_spec.shard_mapping_id)
if shard_mappings is None:
raise _errors.ShardingError(SHARD_MAPPING_NOT_FOUND %
(range_sharding_spec.shard_mapping_id, ))
#Fetch the shard mapping definition. There is only one shard mapping
#definition associated with all of the shard mappings.
shard_mapping_defn = ShardMapping.fetch_shard_mapping_defn(
range_sharding_spec.shard_mapping_id)
if shard_mapping_defn is None:
raise _errors.ShardingError(SHARD_MAPPING_DEFN_NOT_FOUND %
(range_sharding_spec.shard_mapping_id, ))
shard = Shards.fetch(shard_id)
if shard is None:
raise _errors.ShardingError(SHARD_NOT_FOUND % (shard_id, ))
#Both of the shard_mappings retrieved will be of the same sharding
#type. Hence it is safe to use one of them to retireve the sharding type.
if shard_mappings[0].type_name == "HASH":
return HashShardingSpecification.fetch(shard_id), \
shard, shard_mappings, shard_mapping_defn
else:
return range_sharding_spec, shard, shard_mappings, shard_mapping_defn
def _add_shard(shard_mapping_id, groupid_lb_list, state, update_only=False):
"""Add the RANGE shard specification. This represents a single instance
of a shard specification that maps a key RANGE to a server.
:param shard_mapping_id: The unique identification for a shard mapping.
:param groupid_lb_list: The list of group_id, lower_bounds pairs in the
format, group_id/lower_bound, group_id/lower_bound... .
:param state: Indicates whether a given shard is ENABLED or DISABLED
:param update_only: Only update the state store and skip adding range checks.
:return: True if the add succeeded.
False otherwise.
:raises: ShardingError If the group on which the shard is being
created does not exist,
If the shard_mapping_id is not found,
If adding the shard definition fails,
If the state of the shard is an invalid
value,
If the range definition is invalid.
"""
shard_mapping = ShardMapping.fetch_shard_mapping_defn(shard_mapping_id)
if shard_mapping is None:
raise _errors.ShardingError(SHARD_MAPPING_NOT_FOUND % \
(shard_mapping_id, ))
schema_type = shard_mapping[1]
if len(RangeShardingSpecification.list(shard_mapping_id)) != 0:
raise _errors.ShardingError(SHARDS_ALREADY_EXIST)
group_id_list, lower_bound_list = \
_utils.get_group_lower_bound_list(groupid_lb_list)
if (len(group_id_list) != len(lower_bound_list)) and\
schema_type == "RANGE":
raise _errors.ShardingError(LOWER_BOUND_GROUP_ID_COUNT_MISMATCH)
if len(lower_bound_list) != 0 and schema_type == "HASH":
raise _errors.ShardingError(LOWER_BOUND_AUTO_GENERATED)
if schema_type in Shards.VALID_RANGE_SHARDING_TYPES:
for lower_bound in lower_bound_list:
if not SHARDING_DATATYPE_HANDLER[schema_type].\
is_valid_lower_bound(lower_bound):
raise _errors.ShardingError(
INVALID_LOWER_BOUND_VALUE % (lower_bound, ))
state = state.upper()
if state not in Shards.VALID_SHARD_STATES:
raise _errors.ShardingError(INVALID_SHARD_STATE % (state, ))
for index, group_id in enumerate(group_id_list):
shard = Shards.add(group_id, state)
shard_id = shard.shard_id
if schema_type == "HASH":
HashShardingSpecification.add(
shard_mapping_id,
shard_id
)
_LOGGER.debug(
"Added Shard (map id = %s, id = %s).",
shard_mapping_id,
shard_id
)
else:
range_sharding_specification = \
SHARDING_SPECIFICATION_HANDLER[schema_type].add(
shard_mapping_id,
lower_bound_list[index],
shard_id
)
_LOGGER.debug(
"Added Shard (map id = %s, lower bound = %s, id = %s).",
range_sharding_specification.shard_mapping_id,
range_sharding_specification.lower_bound,
range_sharding_specification.shard_id
)
if not update_only:
#If the shard is added in a DISABLED state do not setup replication
#with the primary of the global group. Basically setup replication only
#if the shard is ENABLED.
if state == "ENABLED":
_setup_shard_group_replication(shard_id)
if not update_only:
#Add the shard limits into the metadata present in each of the shards.
_events.trigger_within_procedure(
ADD_SHARD_RANGE_CHECK,
shard_mapping_id,
schema_type
)
def _add_shard(shard_mapping_id, groupid_lb_list, state):
"""Add the RANGE shard specification. This represents a single instance
of a shard specification that maps a key RANGE to a server.
:param shard_mapping_id: The unique identification for a shard mapping.
:param groupid_lb_list: The list of group_id, lower_bounds pairs in the
format, group_id/lower_bound, group_id/lower_bound... .
:param state: Indicates whether a given shard is ENABLED or DISABLED
:return: True if the add succeeded.
False otherwise.
:raises: ShardingError If the group on which the shard is being
created does not exist,
If the shard_mapping_id is not found,
If adding the shard definition fails,
If the state of the shard is an invalid
value,
If the range definition is invalid.
"""
shard_mapping = ShardMapping.fetch_shard_mapping_defn(shard_mapping_id)
if shard_mapping is None:
raise _errors.ShardingError(SHARD_MAPPING_NOT_FOUND % \
(shard_mapping_id, ))
schema_type = shard_mapping[1]
if len(RangeShardingSpecification.list(shard_mapping_id)) != 0:
raise _errors.ShardingError(SHARDS_ALREADY_EXIST)
group_id_list, lower_bound_list = \
_utils.get_group_lower_bound_list(groupid_lb_list)
if (len(group_id_list) != len(lower_bound_list)) and\
schema_type == "RANGE":
raise _errors.ShardingError(LOWER_BOUND_GROUP_ID_COUNT_MISMATCH)
if len(lower_bound_list) != 0 and schema_type == "HASH":
raise _errors.ShardingError(LOWER_BOUND_AUTO_GENERATED)
if schema_type in Shards.VALID_RANGE_SHARDING_TYPES:
for lower_bound in lower_bound_list:
if not SHARDING_DATATYPE_HANDLER[schema_type].\
is_valid_lower_bound(lower_bound):
raise _errors.ShardingError(INVALID_LOWER_BOUND_VALUE %
(lower_bound, ))
state = state.upper()
if state not in Shards.VALID_SHARD_STATES:
raise _errors.ShardingError(INVALID_SHARD_STATE % (state, ))
for index, group_id in enumerate(group_id_list):
shard = Shards.add(group_id, state)
shard_id = shard.shard_id
if schema_type == "HASH":
HashShardingSpecification.add(shard_mapping_id, shard_id)
_LOGGER.debug("Added Shard (map id = %s, id = %s).",
shard_mapping_id, shard_id)
else:
range_sharding_specification = \
SHARDING_SPECIFICATION_HANDLER[schema_type].add(
shard_mapping_id,
lower_bound_list[index],
shard_id
)
_LOGGER.debug(
"Added Shard (map id = %s, lower bound = %s, id = %s).",
range_sharding_specification.shard_mapping_id,
range_sharding_specification.lower_bound,
range_sharding_specification.shard_id)
#If the shard is added in a DISABLED state do not setup replication
#with the primary of the global group. Basically setup replication only
#if the shard is ENABLED.
if state == "ENABLED":
_setup_shard_group_replication(shard_id)
