def _setup_shard_switch_move(shard_id, source_group_id, destination_group_id,
update_only):
"""Setup the moved shard to map to the new group.
:param shard_id: The shard ID of the shard that needs to be moved.
:param source_group_id: The group_id of the source shard.
:param destination_group_id: The ID of the group to which the shard
needs to be moved.
:update_only: Only update the state store and skip provisioning.
"""
#Fetch the Range sharding specification. When we start implementing
#heterogenous sharding schemes, we need to find out the type of
#sharding scheme and we should use that to find out the sharding
#implementation.
_, source_shard, _, shard_mapping_defn = \
_services_sharding._verify_and_fetch_shard(shard_id)
#Setup replication between the shard group and the global group.
_group_replication.setup_group_replication \
(shard_mapping_defn[2], destination_group_id)
#set the shard to point to the new group.
source_shard.group_id = destination_group_id
#Stop the replication between the global server and the original
#group associated with the shard.
_group_replication.stop_group_slave\
(shard_mapping_defn[2], source_group_id, True)
#Reset the read only flag on the source server.
source_group = Group.fetch(source_group_id)
if source_group is None:
raise _errors.ShardingError(_services_sharding.SHARD_GROUP_NOT_FOUND %
(source_group_id, ))
master = MySQLServer.fetch(source_group.master)
if master is None:
raise _errors.ShardingError(
_services_sharding.SHARD_GROUP_MASTER_NOT_FOUND)
if not update_only:
master.connect()
master.read_only = False
def _setup_shard_switch_split(shard_id, source_group_id, destination_group_id,
split_value, cmd, update_only):
"""Setup the moved shard to map to the new group.
:param shard_id: The shard ID of the shard that needs to be moved.
:param source_group_id: The group_id of the source shard.
:param destn_group_id: The ID of the group to which the shard needs to
be moved.
:param split_value: Indicates the value at which the range for the
particular shard will be split. Will be set only
for shard split operations.
:param cmd: Indicates the type of re-sharding operation.
:update_only: Only update the state store and skip provisioning.
"""
#Fetch the Range sharding specification.
range_sharding_spec, source_shard, shard_mappings, shard_mapping_defn = \
_services_sharding._verify_and_fetch_shard(shard_id)
#Disable the old shard
source_shard.disable()
#Remove the old shard.
range_sharding_spec.remove()
source_shard.remove()
#Add the new shards. Generate new shard IDs for the shard being
#split and also for the shard that is created as a result of the split.
new_shard_1 = Shards.add(source_shard.group_id, "DISABLED")
new_shard_2 = Shards.add(destination_group_id, "DISABLED")
#Both of the shard mappings associated with this shard_id should
#be of the same sharding type. Hence it is safe to use one of the
#shard mappings.
if shard_mappings[0].type_name == "HASH":
#In the case of a split involving a HASH sharding scheme,
#the shard that is split gets a new shard_id, while the split
#gets the new computed lower_bound and also a new shard id.
#NOTE: How the shard that is split retains its lower_bound.
HashShardingSpecification.add_hash_split(
range_sharding_spec.shard_mapping_id,
new_shard_1.shard_id,
range_sharding_spec.lower_bound
)
HashShardingSpecification.add_hash_split(
range_sharding_spec.shard_mapping_id,
new_shard_2.shard_id,
split_value
)
else:
#Add the new ranges. Note that the shard being split retains
#its lower_bound, while the new shard gets the computed,
#lower_bound.
RangeShardingSpecification.add(
range_sharding_spec.shard_mapping_id,
range_sharding_spec.lower_bound,
new_shard_1.shard_id
)
RangeShardingSpecification.add(
range_sharding_spec.shard_mapping_id,
split_value,
new_shard_2.shard_id
)
#The source shard group master would have been marked as read only
#during the sync. Remove the read_only flag.
source_group = Group.fetch(source_group_id)
if source_group is None:
raise _errors.ShardingError(_services_sharding.SHARD_GROUP_NOT_FOUND %
(source_group_id, ))
source_group_master = MySQLServer.fetch(source_group.master)
if source_group_master is None:
raise _errors.ShardingError(
_services_sharding.SHARD_GROUP_MASTER_NOT_FOUND)
source_group_master.connect()
source_group_master.read_only = False
#Setup replication for the new group from the global server
_group_replication.setup_group_replication \
(shard_mapping_defn[2], destination_group_id)
#Enable the split shards
new_shard_1.enable()
new_shard_2.enable()
#Trigger changing the mappings for the shard that was copied
if not update_only:
_events.trigger_within_procedure(
PRUNE_SHARDS, new_shard_1.shard_id, new_shard_2.shard_id
)
def _check_shard_information(shard_id, destn_group_id, mysqldump_binary,
mysqlclient_binary, split_value, config_file, cmd,
update_only):
"""Verify the sharding information before starting a re-sharding operation.
:param shard_id: The destination shard ID.
:param destn_group_id: The Destination group ID.
:param mysqldump_binary: The path to the mysqldump binary.
:param mysqlclient_binary: The path to the mysqlclient binary.
:param split_value: The point at which the sharding definition
should be split.
:param config_file: The complete path to the fabric configuration
file.
:param cmd: Indicates if it is a split or a move being executed.
:param update_only: If the operation is a update only operation.
"""
if not _services_utils.is_valid_binary(mysqldump_binary):
raise _errors.ShardingError(
_services_sharding.MYSQLDUMP_NOT_FOUND % mysqldump_binary)
if not _services_utils.is_valid_binary(mysqlclient_binary):
raise _errors.ShardingError(
_services_sharding.MYSQLCLIENT_NOT_FOUND % mysqlclient_binary)
if cmd == "SPLIT":
range_sharding_spec, _, shard_mappings, _ = \
_services_sharding._verify_and_fetch_shard(shard_id)
upper_bound =\
SHARDING_SPECIFICATION_HANDLER[shard_mappings[0].type_name].\
get_upper_bound(
range_sharding_spec.lower_bound,
range_sharding_spec.shard_mapping_id,
shard_mappings[0].type_name
)
#If the underlying sharding scheme is a HASH. When a shard is split,
#all the tables that are part of the shard, have the same sharding
#scheme. All the shard mappings associated with this shard_id will be
#of the same sharding type. Hence it is safe to use one of the shard
#mappings.
if shard_mappings[0].type_name == "HASH":
if split_value is not None:
raise _errors.ShardingError(
_services_sharding.NO_LOWER_BOUND_FOR_HASH_SHARDING
)
if upper_bound is None:
#While splitting a range, retrieve the next upper bound and
#find the mid-point, in the case where the next upper_bound
#is unavailable pick the maximum value in the set of values in
#the shard.
upper_bound = HashShardingSpecification.fetch_max_key(shard_id)
#Calculate the split value.
split_value =\
SHARDING_DATATYPE_HANDLER[shard_mappings[0].type_name].\
split_value(
range_sharding_spec.lower_bound,
upper_bound
)
elif shard_mappings[0].type_name == "RANGE" and\
split_value is not None:
if not (SHARDING_DATATYPE_HANDLER[shard_mappings[0].type_name].\
is_valid_split_value(
split_value, range_sharding_spec.lower_bound,
upper_bound
)
):
raise _errors.ShardingError(
_services_sharding.INVALID_LOWER_BOUND_VALUE %
(split_value, )
)
elif shard_mappings[0].type_name == "RANGE" and split_value is None:
raise _errors.ShardingError(
_services_sharding.SPLIT_VALUE_NOT_DEFINED
)
#Ensure that the group does not already contain a shard.
if (Shards.lookup_shard_id(destn_group_id) is not None):
raise _errors.ShardingError(
_services_sharding.SHARD_MOVE_DESTINATION_NOT_EMPTY %
(destn_group_id, )
)
#Fetch the group information for the source shard that
#needs to be moved.
source_shard = Shards.fetch(shard_id)
if source_shard is None:
raise _errors.ShardingError(
_services_sharding.SHARD_NOT_FOUND % (shard_id, ))
#Fetch the group_id and the group that hosts the source shard.
source_group_id = source_shard.group_id
source_group = Group.fetch(source_group_id)
destn_group = Group.fetch(destn_group_id)
if destn_group is None:
raise _errors.ShardingError(
_services_sharding.SHARD_GROUP_NOT_FOUND %
(destn_group_id, ))
if not update_only:
_events.trigger_within_procedure(
BACKUP_SOURCE_SHARD, shard_id, source_group_id, destn_group_id,
mysqldump_binary, mysqlclient_binary, split_value, config_file,
cmd, update_only
)
else:
_events.trigger_within_procedure(
SETUP_RESHARDING_SWITCH, shard_id, source_group_id, destn_group_id,
split_value, cmd, update_only
)
