def _setup_shard_switch_split(shard_id, source_group_id, destination_group_id,
split_value, prune_limit, 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 prune_limit: The number of DELETEs that should be
done in one batch.
: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()
destination_group = Group.fetch(destination_group_id)
if destination_group is None:
raise _errors.ShardingError(_services_sharding.SHARD_GROUP_NOT_FOUND %
(destination_group_id, ))
destn_group_master = MySQLServer.fetch(destination_group.master)
if destn_group_master is None:
raise _errors.ShardingError(
_services_sharding.SHARD_GROUP_MASTER_NOT_FOUND)
destn_group_master.connect()
#Make the destination group as read only to disable updates until the
#connectors update their caches, thus avoiding inconsistency.
destn_group_master.read_only = True
#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 sleep ensures that the connector have refreshed their caches with the
#new shards that have been added as a result of the split.
time.sleep(_utils.TTL)
#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()
#Kill all the existing connections on the servers
source_group.kill_connections_on_servers()
#Allow connections on the source group master
source_group_master.read_only = False
#Allow connections on the destination group master
destn_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, prune_limit
)
def _setup_shard_switch_split(shard_id, source_group_id, destination_group_id,
split_value, prune_limit, 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 prune_limit: The number of DELETEs that should be
done in one batch.
: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()
destination_group = Group.fetch(destination_group_id)
if destination_group is None:
raise _errors.ShardingError(_services_sharding.SHARD_GROUP_NOT_FOUND %
(destination_group_id, ))
destn_group_master = MySQLServer.fetch(destination_group.master)
if destn_group_master is None:
raise _errors.ShardingError(
_services_sharding.SHARD_GROUP_MASTER_NOT_FOUND)
destn_group_master.connect()
#Make the destination group as read only to disable updates until the
#connectors update their caches, thus avoiding inconsistency.
destn_group_master.read_only = True
#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 sleep ensures that the connector have refreshed their caches with the
#new shards that have been added as a result of the split.
time.sleep(_utils.TTL)
#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()
#Kill all the existing connections on the servers
source_group.kill_connections_on_servers()
#Allow connections on the source group master
source_group_master.read_only = False
#Allow connections on the destination group master
destn_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, prune_limit)
