There are certain limitations of inbound replication of the MySQL Database Service.

• Inbound replication is not a managed functionality. You are responsible for configuring and maintaining the channel, and for ensuring that the traffic between source and replica is properly configured.
• Only row-based and GTID-based replication is supported.
• Multi-source replication and replication filters are not supported.
• Changes to the mysql schema are not replicated and causes replication to stop.
• Source and replica must run with the same lower_case_table_names value. See Initialization Variables.
• The inbound applier runs under the privileges of the admin user of the DB system. See Default MySQL Privileges.
• To configure an inbound replication channel on a highly available DB system, import your data to the DB system before enabling high availability, then enable your inbound replication channel.
• The channel is suspended when the highly available DB system is upgraded. The channel is resumed when the upgrade process is complete.

Inbound replication requires you to properly configure your MySQL source.

You require the following:

• A properly configured replication user on the source server. See Creating a Replication User on a Source Server Using a Command-Line Client.
• If you intend to encrypt the communication between source and replica, a properly configured source to use SSL. See Server-side Configuration for Encrypted Connections.
• A properly configured egress seclist, VPN, or on-premise firewalls of your MySQL source to allow traffic from the entire subnet your DB system is present in and not just the IP address of your DB system. This is because the IP address of the replication channel can change in some scenarios such as during upgrades.

Use the Console to create a replication channel.

1. Open the navigation menu and select Databases. Under MySQL do one of the following:
   • Click Channels and click Create Channel.
   • Click DB Systems and from the list of DB systems, click the name of your DB system. Click More Actions, and select Create Channel.
   • Click the Actions menu present on the same line as your DB system and select Create Channel.
2. On the Create channel panel, provide the following details:
   • Create in Compartment: If you want to create the channel in a compartment other than the current compartment, select the required compartment from the list. If you do not select a different compartment, the current compartment is used.
     Note
     
     Create the channel in the same compartment as the target DB system.
   • Name: (Optional) Specify a user-friendly display-name for the channel. This name is not related to the Channel Name defined in the Target DB System definition. It is used solely to label the channel. If you do not specify a name, one is generated for you in the format, mysqlchannelYYYYMMDDHHMMSS.
   • Enabled Automatically Upon Creation: Specify whether the channel starts automatically on successful creation. It is enabled by default. If you disable this option, enable the channel manually.
   • Description: (Optional) Specify a user-friendly description of the channel and its purpose.
   • Source Connection: Configure the MySQL source from where you want to replicate the data:
     • Hostname: Specify the hostname of the MySQL source. You can either specify an IP address or a fully qualified domain name.
     • Port: (Optional) Specify the port number the MySQL source listens on. The default value is 3306.
     • Username: Specify the replication username defined on the MySQL source. The replication channel uses these credentials to connect to the source.
     • Password: Specify the password of the replication user. See Creating a Replication User on a Source Server Using a Command-Line Client.
     • SSL Mode: Select the required SSL mode. The selected mode is used to populate the SSL-specific values of the connection to the MySQL Source. Select either of the following SSL modes:
       • Disabled (DISABLED): Establishes an unencrypted connection between the source and target.
       • Required (REQUIRED): (Default) If the server supports encrypted connection, establishes an encrypted connection. The connection attempt fails if an encrypted connection cannot be established.
       • Verify Certificate Authority (VERIFY_CA): Like the Required mode, establishes an encrypted connection if the server supports encrypted connections and additionally verifies the Certificate Authority certificate configured on the source against the Certificate Authority's X509 certificate (PEM). You have to upload your Certificate Authority's X509 certificate.
       • Verify Identity (VERIFY_IDENTITY): Like the Verify Certificate Authority mode, establishes an encrypted connection, verifies the Certificate Authority's certificate, and additionally verifies the source hostname, which you define in the source SSL certificate, against the hostname that you define in the Hostname field. You have to upload your Certificate Authority's X509 certificate.
       • Certificate Authority's X509 certificate (PEM): Enables you to upload the source Certificate Authority's X509 certificate in PEM format. It is displayed only when you select the Verify Certificate Authority or Verify Identity mode. The certificate is used to verify the Certificate Authority's certificate on the source.
   • Target DB System: Configure the DB system to which you want to replicate the data.
     • Applier Username: (Optional) Specify the username of the replication applier on the target DB system. If you do not specify a username, the credentials of the administrator of the DB system is used.
     • Channel Name: (Optional) Specify the replication channel name. The target DB System uses the replication channel to communicate with the MySQL Source. If you do not specify a name, replication_channel is used.
     • Select a DB System: Select the DB system to use as the replication target.
       Note
       
       If you create the channel from the DB System Details page, or from the Actions menu, the target DB system is automatically selected and you cannot change it. You can view the target DB system at the top of the page.

Use MySQL Shell to import data from your source to your replica DB system before starting inbound replication.

1. Export your source data to Object Storage. See Exporting Data Using MySQL Shell.
2. Import the source data to your replica DB system. See Importing Data Using Object Storage Bucket and MySQL Shell.
3. Retrieve the value of gtidExecuted from the dump in Object Storage.
   Note
   
   The dump loading utility does not automatically apply the gtid_executed GTID set from the source MySQL instance on the target DB system. The GTID set is included in the dump metadata from MySQL Shell instance dump utility, schema dump utility, or table dump utility, as the gtidExecuted field in the @.json dump file.
4. Connect to the replica DB system and set the value of gtidPurged using the following command:

   CALL sys.SET_GTID_PURGED("+<gtidSet>")

   <gtidSet> is the value in the gtidExecuted field in the @.json dump file.

   Note
   
   This process is for new imports only. If you are attempting to recover from a replication lag, see Resolving Replica and Source Synchronization Issues.
5. Create and start the channel. See Creating a Replication Channel.

Use the Console to manage your MySQL DB system replication channels.

• Channel Details
• Checking the Channel State
• Enabling or Disabling a Channel
• Resetting a Channel
• Resuming a Channel
• Editing a Channel

To use outbound replication of MySQL Database Service, you require certain configurations.

• The replica must apply the source transactions before the source binary log is purged. The default value of binlog_expire_logs_seconds is 3600 seconds (1 hour). If you require a longer value, create a new configuration with the required expiration value and create a new source DB system using the new configuration.
• Your VCN and local network must be configured to permit replication traffic between the source DB system and external replica.
• The external replicas must run with the following parameters:
  • gtid-mode=ON. See gtid_mode.
  • enforce-gtid-consistency. See enforce_gtid_consistency.
  • partial-revokes=ON. See partial_revokes.
  • lower_case_table_names. The replica must run with the same value as the source DB System. See Initialization Variables.
• The replica must contain the same timezone definitions as the DB system. The default timezone of MySQL Database Service is UTC. See Populating the Timezone Tables.
• Outbound replication from a DB system to an external replica, or another DB system, requires you to create a dump of the source DB system using MySQL Shell dumpInstance utility and import that dump on the replica, including users, before starting replication. See Exporting and Importing Overview.
• Users on the source must be present on the replica. Partial revokes requires that the roles and users creating grants are present on the replica. The users on the source are exported as part of the dump and must be imported to the replica.
• On external replicas, the user must have the necessary privileges to load users and data.
• The server_id value must be defined on your external replica and be unique in your replication topology. The server_uuid value must also be unique.

Use MySQL Shell to export the DB system source instance to Object Storage.

1. Connect to your DB system using MySQL Shell. See Connecting to a DB System Using SSH and MySQL Client and Exporting and Importing Overview.
2. In the JS execution mode, run the following command:

   util.dumpInstance("prefix", {osBucketName: "bucket", ocimds: true, threads: n})

   • util.dumpInstance: Export all data in the MySQL instance.
   • prefix: (Optional) Add a prefix to the files uploaded to the bucket. See Exporting and Importing Overview.
   • ocimds: (Optional) Check your data for compatibility with MySQL Database Service. Specify this option only if you intend to import the dump into another DB system. If you are exporting dump to an external replica, do not specify this option.
   • osBucketName: Specify the case-sensitive name of the Object Storage bucket to export to.
   • threads: Specify the number of processing threads to use for this task. The default value is 4.

Use MySQL Shell to import the source data and users from an Object Storage bucket to a replica.

1. In MySQL Shell, connect to your replica, and run the following command:

   util.loadDump("prefix", {osBucketName: "bucket", threads: n, 
       loadUsers: true, updateGtidSet: "append"})

   • util.loadDump: Import data from the specified Object Storage bucket to MySQL DB system.
   • prefix: (Optional) If the data is uploaded to Object Storage with a prefix, specify that prefix in the import command. See Exporting and Importing Overview.
   • osBucketName: Specify the name of the Object Storage bucket to import from.
   • threads: Specify the number of processing threads to use for this task. The default value is 4. It is recommended to set this parameter to the number of CPU cores available on the local database server or twice the number of OCPUs used by the target MySQL DB system.
   • loadUsers: true: Load the users defined in the source instance.
   • updateGtidSet: "append": Apply the gtid_executed GTID set from the source, as recorded in the dump metadata, to the gtid_purged GTID set on the replica. See MySQL Shell Dump Loading Utility.

Use a command-line client such as MySQL Shell or MySQL Client to create a correctly configured replication user with appropriate privileges on the source server.

1. Open MySQL Shell and connect to your source server.
2. Run the following command to create a replication user, rpluser001, with the password Rpl001#!, and to permit only encrypted connections for all accounts named by the statement:

   CREATE USER rpluser001@'%' IDENTIFIED BY 'Rpl001#!' REQUIRE SSL;

   Note
   
   The password must be between 8 and 32 characters and contain at least one numeric character, one special character, one uppercase, and one lowercase character.
3. Run the following command to grant the REPLICATION SLAVE privilege to the new replication user:

   GRANT REPLICATION SLAVE on *.* to rpluser001@'%';

Use a command-line client such as MySQL Client or MySQL Shell to configure outbound replication from a DB system to an external replica.

1. Open MySQL Shell and connect to your replica.
2. On the replica, specify the replication source by running the following command:

   CHANGE REPLICATION SOURCE TO SOURCE_HOST='<DBSystemIPAddress>', 
   SOURCE_PORT=3306, SOURCE_USER='<SourceUser>', SOURCE_PASSWORD='<SourcePassword>', SOURCE_SSL=1, 
   SOURCE_AUTO_POSITION=1 FOR CHANNEL '<ChannelName>';

   • SOURCE_HOST: Specify the IP address of the source DB system.
   • SOURCE_PORT: Specify the port the source is configured to use. The default port is 3306.
   • SOURCE_USER: Specify the username of the replication user created on the source DB system.
   • SOURCE_PASSWORD: Specify the password of the source replication user.
   • SOURCE_SSL=1: Specify an SSL-encrypted connection.
   • SOURCE_AUTO_POSITION=1: Specify that the replica connects to the source using the autopositioning feature of GTID-based replication, rather than a binary log file based position.
   • CHANNEL: Specify a replication channel. This either uses an existing replication channel with the supplied channel name or, if the channel does not exist, creates one using the supplied name. This channel is defined on the replica server, it does not require a channel defined in MySQL Database Service Channels.
3. To start replication, run the following command on the replica:

   START REPLICA FOR CHANNEL '<ChannelName>';

   <ChannelName>: Specify the name of the channel.

4. To view the replication status, run any of the following command:
   • On the replica:

     SHOW REPLICA STATUS \G;

     SHOW PROCESSLIST;

   • On the source DB system:

     SHOW REPLICAS;

     SHOW PROCESSLIST;

Use the Console to configure outbound replication from a source DB system to a replica DB system.

1. Create a replication channel on DBSystem2 specifying DBSystem1 as the source. See Creating a Replication Channel.