MySQL Shell 8.0 Release Notes
You deploy InnoDB ReplicaSet in a similar way to
InnoDB Cluster. First you configure some MySQL server
instances, the minimum is two instances, see
Section 6.1, “MySQL AdminAPI”. One functions as the
primary, in this tutorial rs-1; the other
instance functions as the secondary, in this tutorial
rs-2; which replicates the transactions
applied by the primary. This is the equivalent of the source and
replica known from asynchronous MySQL replication. Then you
connect to one of the instances using MySQL Shell, and create a
ReplicaSet. Once the ReplicaSet has been created, you can add
instances to it.
InnoDB ReplicaSet is compatible with sandbox instances, which you can use to deploy locally, for example for testing purposes. See Deploying Sandbox Instances for instructions. However, this tutorial assumes you are deploying a production InnoDB ReplicaSet, where each instance is running on a different host.
To use InnoDB ReplicaSet you should be aware of the following prerequisites:
Only instances running MySQL version 8.0 and later are supported
Only GTID-based replication is supported, binary log file position replication is not compatible with InnoDB ReplicaSet
Only Row Based Replication (RBR) is supported, Statement Based Replication (SBR) is unsupported
Replication filters are not supported
Unmanaged replication channels are not allowed on any instance
A ReplicaSet consists of maximum one primary instance, and one or multiple secondaries are supported. Although there is no limit to the number of secondaries you can add to a ReplicaSet, each MySQL Router connected to a ReplicaSet has to monitor each instance. Therefore, the more instances that are added to a ReplicaSet, the more monitoring has to be done.
The ReplicaSet must be entirely managed by MySQL Shell. For example, the replication account is created and managed by MySQL Shell. Making configuration changes to the instance outside of MySQL Shell, for example using SQL statements directly to change the primary, is not supported. Always use MySQL Shell to work with InnoDB ReplicaSet.
AdminAPI and InnoDB ReplicaSet enable you to work with MySQL replication without a deep understanding of the underlying concepts. However, for background information see Replication.
Use
dba.configureReplicaSetInstance(
to configure each instance you want to use in your replica
set. MySQL Shell can either connect to an instance and then
configure it, or you can pass in instance)instance
to configure a specific remote instance. To use an instance in
a ReplicaSet, it must support persisting settings. See
Persisting Settings.
When you connect to the instance for administration tasks you
require a user with suitable privileges. The preferred method
to create users to administer a ReplicaSet is using the
setupAdminAccount() operation. See
Creating User Accounts for Administration.
Alternatively, the
dba.configureReplicaSetInstance() operation
can optionally create an administrator account, if the
clusterAdmin option is provided. The
account is created with the correct set of privileges required
to manage InnoDB ReplicaSet.
Tip
The administrator account must have the same user name and password across all instances of the same cluster or replica set.
To configure the instance at rs-1:3306,
with a cluster administrator named rsadmin
issue:
mysql-js> dba.configureReplicaSetInstance('root@rs-1:3306', {clusterAdmin: "'rsadmin'@'rs-1%'"});The interactive prompt requests the password required by the specified user. To configure the instance MySQL Shell is currently connected to, you can specify a null instance definition. For example issue:
mysql-js> dba.configureReplicaSetInstance('', {clusterAdmin: "'rsadmin'@'rs-1%'"});The interactive prompt requests the password required by the specified user. This checks the instance which MySQL Shell is currently connected to is valid for use in an InnoDB ReplicaSet. Settings which are not compatible with InnoDB ReplicaSet are configured if possible. The cluster administrator account is created with the privileges required for InnoDB ReplicaSet.
Once you have configured your instances, connect to an
instance and use dba.createReplicaSet() to
create a managed ReplicaSet that uses MySQL asynchronous
replication, as opposed to MySQL Group Replication used by
InnoDB Cluster. The MySQL instance which MySQL Shell is
currently connected to is used as the initial primary of the
ReplicaSet.
The dba.createReplicaSet() operation
performs several checks to ensure that the instance state and
configuration are compatible with a managed ReplicaSet and if
so, a metadata schema is initialized on the instance. If you
want to check the operation but not actually make any changes
to the instances, use the dryRun option.
This checks and shows what actions the MySQL Shell would take
to create the ReplicaSet. If the ReplicaSet is created
successfully, a ReplicaSet object is
returned. Therefore it is best practice to assign the returned
ReplicaSet to a variable. This enables you
to work with the ReplicaSet, for example by calling the
ReplicaSet.status()example on instance
rs-1 and assign it to the
rs variable, issue:
mysql-js> \connect root@rs-1:3306
...
mysql-js> var rs = dba.createReplicaSet("example")
A new replicaset with instance 'rs-1:3306' will be created.
* Checking MySQL instance at rs-1:3306
This instance reports its own address as rs-1:3306
rs-1:3306: Instance configuration is suitable.
* Updating metadata...
ReplicaSet object successfully created for rs-1:3306.
Use rs.add_instance() to add more asynchronously replicated instances to this replicaset
and rs.status() to check its status.
To verify that the operation was successful, you work with the
returned ReplicaSet object. For example
this provides the
ReplicaSet.status()ReplicaSet to
the variable rs, so issue:
mysql-js> rs.status()
{
"replicaSet": {
"name": "example",
"primary": "rs-1:3306",
"status": "AVAILABLE",
"statusText": "All instances available.",
"topology": {
"rs-1:3306": {
"address": "rs-1:3306",
"instanceRole": "PRIMARY",
"mode": "R/W",
"status": "ONLINE"
}
},
"type": "ASYNC"
}
}
This output shows that the ReplicaSet named
example has been created, and that the
primary is rs-1. Currently there is only
one instance, and the next task is to add more instances to
the ReplicaSet.