MySQL Utilities 1.4 Manual  /  ...  /  Backing Store Tables

8.5.1. Backing Store Tables

The checkpoints table stores information on procedures' executions and is used to safely resume executing a procedure after a crash and recovery:

Table 8.1. checkpoints

Column Type Comment
proc_uuid varchar(40) The procedure's unique identification
lockable_objects blob Set of objects locked by the procedure
job_uuid varchar(60) The job's unique identification
sequence int(11) The job's sequence in the execution
action_fqn text Reference to the fully qualified name of the function to be executed on behalf of the job
param_args blob Positional arguments to the job's function
param_kwargs blob Keyword arguments to the job's function
started double(16,6) When the job started
finished double(16,6) When the job finished

The error_log table contains information on servers' errors reported.

Table 8.2. error_log

Column Type Comment
server_uuid varchar(40) The server_uuid value from the server that has raised an error
reported timestamp(6) When the error was reported
reporter varchar(64) Who reported the error: IP address, host name
error text Error message or code reported

The group_replication table defines replication among global groups and groups used in shards. They are used primarily for shard splitting, moving, and global updates.

Table 8.3. group_replication

Column Type
master_group_id varchar(64)
slave_group_id varchar(64)

The groups table contains information about the groups being managed.

Table 8.4. groups

Column Type Comment
group_id varchar(64) The identifier for the group
description varchar(256) A description of the group
master_uuid varchar(40) The server_uuid value from the master server
master_defined timestamp(6) When the current master was defined.
status bit(1) 1 if the group is being monitored, 0 otherwise

The permissions table contains information on rights to access the different sub-systems in Fabric. Currently, a core sub-system is formally defined:

Table 8.5. permissions

Column Type Comment
permission_id int(10) unsigned Permission's ID
subsystem varchar(60) Sub-system identification
component varchar(60) Sub-system component
function varchar(60) Sub-system function. Currently, this is not used
description varchar(1000) Description

The roles table contains information on possible roles a user may have and by consequence his/her permissions:

Table 8.6. roles

Column Type Comment
role_id int(10) unsigned Roles' ID
name varchar(80) Role's name
description varchar(1000) Role's description

The role_permissions table associates roles and permissions:

Table 8.7. role_permissions

Column Type Comment
role_id int(10) unsigned Roles' ID
permission_id int(10) unsigned Permission's ID

The servers table contains a list of all servers managed by Fabric.

Table 8.8. servers

Column Type Comment
server_uuid varchar(40) UUID of the server
server_address varchar(128) Address of the server
mode int(11) Mode of the server (OFFLINE, READ_ONLY, WRITE_ONLY, READ_WRITE)
status int(11) Status of the server (FAULTY, SPARE, SECONDARY, PRIMARY)
weight float Likelihood of receiving a request
group_id varchar(64) Group the server belongs to

The shard_maps table contains the names and properties of the shard maps.

Table 8.9. shard_maps

Column Type Comment
shard_mapping_id int(11) Shard map identifier
type_name enum('RANGE','HASH') Shard map type
global_group varchar(64) Name of the global group (likely to go away in the next revision)

The shard_ranges table is the sharding index and is used to map a sharding key to a shard.

Table 8.10. shard_ranges

Column Type Comment
shard_mapping_id int(11) Shard map identifier
lower_bound varbinary(16) Lower bound for the range encoded as a binary string
shard_id int(11) Shard identifier (a number)

The shard_tables table lists all tables that are sharded and what sharding map each belongs to. It also names the column by which it is sharded.

Table 8.11. shard_tables

Column Type Comment
shard_mapping_id int(11) Shard map identifier
table_name varchar(64) Fully qualified table name
column_name varchar(64) Column name that is the sharding key

The shards table names the groups where each shard identifier is stored.

Table 8.12. shards

Column Type Comment
shard_id int(11) Shard identifier
group_id varchar(64) Group identifier (a dotted-name)
state enum('DISABLED','ENABLED') Status of the shard; DISABLED means that it is not available for use

The users table identifies the users that might have permission to access the functions in the different sub-systems:

Table 8.13. users

Column Type Comment
user_id int(10) unsigned User's internal ID
username varchar(100) User's name
protocol varchar(200) Protocol that the user is allowed to use to access Fabric and its sub-systems
password varchar(128) Hashed user's password

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