group_replication_group_name

The name of the group which this server instance belongs to. Must be a valid UUID.

group_replication_start_on_boot

Whether the server should start Group Replication or not during server start.

group_replication_local_address

The local address as a host:port formatted string.

group_replication_member_weight

A percentage weight that can be assigned to members to influence the chance of the member being elected as primary in the event that the existing primary leaves the group. Assign numeric weights to members to ensure that specific members are elected, for example during scheduled maintenance of the primary or to ensure certain hardware is prioritised in the event of failover.

group_replication_group_seeds

A list of peer addresses as a comma separated list such as host1:port1,host2:port2. Each address is validated when starting Group Replication and the list must contain at least one valid address. Any invalid host names could cause START GROUP_REPLICATION to fail.

group_replication_force_members

A list of peer addresses as a comma separated list such as host1:port1,host2:port2. This option is used to force a new group membership, in which the excluded members do not receive a new view and are blocked. You need to manually kill the excluded servers. Any invalid host names in the list could cause subsequent START GROUP_REPLICATION statements to fail because they could block group membership.

group_replication_bootstrap_group

Configure this server to bootstrap the group. This option must only be set on one server and only when starting the group for the first time or restarting the entire group. After the group has been bootstrapped, set this option to OFF. It should be set to OFF both dynamically and in the configuration files. Starting two servers or restarting one server with this option set while the group is running may lead to an artificial split brain situation, where two independent groups with the same name are bootstrapped.

group_replication_poll_spin_loops

The number of times the group communication thread waits for the communication engine mutex to be released before the thread waits for more incoming network messages.

group_replication_recovery_retry_count

The number of times that the member that is joining tries to connect to the available donors before giving up.

group_replication_recovery_reconnect_interval

The sleep time, in seconds, between reconnection attempts when no donor was found in the group.

group_replication_recovery_use_ssl

Whether Group Replication recovery connection should use SSL or not.

group_replication_recovery_ssl_ca

The path to a file that contains a list of trusted SSL certificate authorities.

group_replication_recovery_ssl_capath

The path to a directory that contains trusted SSL certificate authority certificates.

group_replication_recovery_ssl_cert

The name of the SSL certificate file to use for establishing a secure connection.

group_replication_recovery_ssl_key

The name of the SSL key file to use for establishing a secure connection.

group_replication_recovery_ssl_cipher

A list of permissible ciphers to use for SSL encryption.

group_replication_recovery_ssl_crl

The path to a directory that contains files containing certificate revocation lists.

group_replication_recovery_ssl_crlpath

The path to a directory that contains files containing certificate revocation lists.

group_replication_recovery_ssl_verify_server_cert

Make the recovery process check the server's Common Name value in the donor sent certificate.

group_replication_recovery_complete_at

Recovery policies when handling cached transactions after state transfer. This option specifies whether a member is marked online after it has received all transactions that it missed before it joined the group (TRANSACTIONS_CERTIFIED) or after it has received and applied them (TRANSACTIONS_APPLIED).

group_replication_components_stop_timeout

Timeout, in seconds, that Group Replication waits for each of the components when shutting down.

group_replication_allow_local_lower_version_join

Allow the current server to join the group even if it has a lower plugin version than the group.

group_replication_allow_local_disjoint_gtids_join

Allow the current server to join the group even if it has transactions not present in the group.

group_replication_auto_increment_increment

Determines the interval between successive column values for transactions that execute on this server instance.

group_replication_compression_threshold

The value in bytes above which (LZ4) compression is enforced. When set to zero, deactivates compression.

group_replication_gtid_assignment_block_size

The number of consecutive GTIDs that are reserved for each member. Each member consumes its blocks and reserves more when needed.

group_replication_ssl_mode

Specifies the security state of the connection between Group Replication members.

group_replication_single_primary_mode

Instructs the group to automatically pick a single server to be the one that handles read/write workload. This server is the PRIMARY and all others are SECONDARIES.

group_replication_transaction_size_limit

Configures the maximum transaction size in bytes which the group accepts. Transactions larger than this size are rolled back. Use this option to avoid large transactions causing the group to fail. A large transaction can cause problems for a group, either in terms of memory allocation or network bandwidth consumption, which may cause the failure detector to trigger because a given member is unreachable while it is busy processing the large transaction. When set to 0 there is no limit to the size of transactions the group accepts, and there may be the risk of large transactions causing the group to fail. Adjust the value of this variable depending on the size of workload you require from the group.

group_replication_unreachable_majority_timeout

Configures how long members that suffer a network partition and cannot connect to the majority wait before leaving the group. By default set to 0, which means that members that find themselves in a minority due to a network partition wait forever to connect the group. In a group of 5 servers (S1,S2,S3,S4,S5), if there is a disconnection between (S1,S2) and (S3,S4,S5) there is a network partition. The first group (S1,S2) is now in a minority because it cannot contact more than half of the group. While the majority group (S3,S4,S5) remains running, the minority group waits forever for a network reconnection. Any transactions processed by the minority group are blocked until Group Replication is stopped using STOP GROUP REPLICATION on the members of the minority.

If configured to a number of seconds, members wait for this amount of time after losing contact with the majority of members before leaving the group. All pending transactions processed by the minority are rolled back and the servers in the minority partition move to the ERROR state and set themselves to super_read_only=ON mode.

group_replication_enforce_update_everywhere_checks

Enable or disable strict consistency checks for multi-primary update everywhere.

group_replication_flow_control_mode

Specifies the mode used for flow control. This variable can be changed without resetting Group Replication.

group_replication_flow_control_hold_percent

Defines what percentage of the group quota remains unused to allow a cluster under flow control to catch up on backlog. A value of 0 implies that no part of the quota is reserved for catching up on the work backlog.

group_replication_flow_control_certifier_threshold

Specifies the number of waiting transactions in the certifier queue that trigger flow control. This variable can be changed without resetting Group Replication.

group_replication_flow_control_applier_threshold

Specifies the number of waiting transactions in the applier queue that trigger flow control. This variable can be changed without resetting Group Replication.

group_replication_flow_control_max_commit_quota

Defines the maximum flow control quota of the group, or the maximum available quota for any period while flow control is enabled. A value of 0 implies that there is no maximum quota set. Cannot be smaller than group_replication_flow_control_min_quota and group_replication_flow_control_min_recovery_quota.

group_replication_flow_control_member_quota_percent

Defines the percentage of the quota that a member should assume is available for itself when calculating the quotas. A value of 0 implies that the quota should be split equally between members that were writers in the last period.

group_replication_flow_control_min_quota

Controls the lowest flow control quota that can be assigned to a member, independently of the calculated minimum quota executed in the last period. A value of 0 implies that there is no minimum quota. Cannot be larger than group_replication_flow_control_max_commit_quota.

group_replication_flow_control_min_recovery_quota

Controls the lowest quota that can be assigned to a member because of another recovering member in the group, independently of the calculated minimum quota executed in the last period. A value of 0 implies that there is no minimum quota. Cannot be larger than group_replication_flow_control_max_commit_quota.

group_replication_flow_control_period

Defines how many seconds to wait between flow control iterations, in which flow control messages are sent and flow control management tasks are run.

group_replication_flow_control_release_percent

Defines how the group quota should be released when flow control no longer needs to throttle the writer members, with this percentage being the quota increase per flow control period. A value of 0 implies that once the flow control thresholds are within limits the quota is released in a single flow control iteration. The range allows the quota to be released at up to 10 times current quota, as that allows a greater degree of adaptation, mainly when the flow control period is large and the quotas are very small.

group_replication_ip_whitelist

Specifies which hosts are permitted to connect to the group. By default set to AUTOMATIC, which permits connections from private subnetworks active on the host. Active interfaces on the host are scanned and those with addresses on private subnetworks are automatically added to the permitted list. Alternatively you can specify the permitted hosts using a comma separated list of IPv4 addresses or subnet CIDR notation. For example 192.168.1.0/24,10.0.0.1.