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Versions from MySQL 5.7.14 allow compression of messages (seeSection 20.7.4, “Message Compression”).

Versions from MySQL 8.0.16 also allow fragmentation of messages (seeSection 20.7.5, “Message Fragmentation”).

Versions from MySQL 8.0.27 also allow the group communication engine to operate with a single consensus leader when the group is in single-primary mode andgroup_replication_paxos_single_leader is set to true (seeSection 20.7.3, “Single Consensus Leader”).

group_replication_get_communication_protocol()

Inspect the Group Replication communication protocol version that is currently in use for a group.

Syntax:

STRING group_replication_get_communication_protocol()

This function has no parameters.

Return value:

The oldest MySQL Server version that can join this group and use the group's communication protocol. Note that thegroup_replication_get_communication_protocol() function returns the minimum MySQL version that the group supports, which might differ from the version number that was passed togroup_replication_set_communication_protocol(), and from the MySQL Server version that is installed on the member where you use the function.

If the protocol cannot be inspected because this server instance does not belong to a replication group, an error is returned as a string.

Example:

SELECT group_replication_get_communication_protocol();+------------------------------------------------+| group_replication_get_communication_protocol() |+------------------------------------------------+| 8.0.44                                          |+------------------------------------------------+

For more information, seeSection 20.5.1.4, “Setting a Group's Communication Protocol Version”.

group_replication_set_communication_protocol()

Downgrade the Group Replication communication protocol version of a group so that members at earlier releases can join, or upgrade the Group Replication communication protocol version of a group after upgrading MySQL Server on all members. TheGROUP_REPLICATION_ADMIN privilege is required to use this function, and all existing group members must be online when you issue the statement, with no loss of majority.

Syntax:

STRING group_replication_set_communication_protocol(version)

Arguments:

Return value:

A string containing the result of the operation, for example whether it was successful or not.

Example:

SELECT group_replication_set_communication_protocol("5.7.25");

For more information, seeSection 20.5.1.4, “Setting a Group's Communication Protocol Version”.