content_image/812282.jpg content_image/812281.jpg
this process, the value of the system variable is permitted to differ between group members, but some transactions on group members might be rolled back. 

group_replication_communication_max_message_size  specifies a maximum message size for Group Replication communications. Messages greater than this size are automatically split into fragments that are sent separately and reassembled by the recipients. For more information, see Section 18.7.4, “Message Fragmentation” . 

A maximum message size of 10485760 bytes (10 MiB) is set by default, which means that fragmentation is used by default in releases from MySQL 8.0.16. The greatest permitted value is the same as the maximum value of the slave_max_allowed_packet  system variable, which is 1073741824 bytes (1 GB). The setting for group_replication_communication_max_message_size  must be less than the slave_max_allowed_packet  setting, because the applier thread cannot handle message fragments larger than slave_max_allowed_packet . To switch off fragmentation, specify a zero value for group_replication_communication_max_message_size . 

In order for members of a replication group to use fragmentation, the group’s communication protocol version must be MySQL 8.0.16 or above. Use the group_replication_get_communication_protocol()  function to view the group’s communication protocol version. If a lower version is in use, group members do not fragment messages. You can use the group_replication_set_communication_protocol()  function to set the group’s communication protocol to a higher version if all group members support it. For more information, see Section 18.5.1.4, “Setting a Group’s Communication Protocol Version” . 

• group_replication_components_stop_timeout 

<img src='content_image/812282.jpg'>

The value of this system variable can be changed while Group Replication is running, but the change only takes effect after you stop and restart Group Replication on the group member. 

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

• group_replication_compression_threshold 

<img src='content_image/812281.jpg'>

