Optimizing MGR Parameters

group_replication_flow_control_mode

QUOTA

Determines whether to enable flow control.

• QUOTA: Flow control is enabled. In this mode, the group_replication_flow_control_applier_threshold and group_replication_flow_control_certifier_threshold parameters can be optimized to improve the MGR performance.

• DISABLE: Flow control is disabled to maximize the MGR performance.

group_replication_flow_control_applier_threshold

2500000

Indicates the number of transactions to be authenticated in the transaction authentication queue of a node before flow control is triggered for the node. The default value is 25000. You are advised to change the value based on your requirements.

group_replication_flow_control_applier_threshold

2500000

Indicates the number of transactions to be authenticated in the transaction playback queue for triggering flow control. The default value is 25000. You are advised to change the value based on your requirements.

group_replication_gtid_assignment_block_size

10000

Specifies the number of consecutive GTIDs reserved for each member.

slave_parallel_type

LOGICAL_CLOCK

Specifies a parallel replication mode.

• DATABASE: database-based parallel replication mode, which is the default value
• LOGICAL_CLOCK: group-based parallel replication mode

slave_parallel_workers

8

Specifies the number of parallel workers for parallel replication. The default value is 0.

sync_relay_log

10000

Determines whether to enable relay log flush to log files.

• 1: Data is first written into the system buffer and then into the log file. This value is the default value.
• 0: The operating system determines when to flush data to a disk.
• n: Data is flushed to a disk when the accumulated value reaches the threshold.

sync_relay_log_info

10000