14.18.1.2 Functions which Configure the Group Replication Mode

The following functions enable you to control the mode which a replication group is running in, either single-primary or multi-primary mode.

• group_replication_switch_to_multi_primary_mode()

  Changes a group running in single-primary mode to multi-primary mode. Must be issued on a member of a replication group running in single-primary mode.

  Syntax:

  STRING group_replication_switch_to_multi_primary_mode()

  This function has no parameters.

  Return value:

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

  Example:

  SELECT group_replication_switch_to_multi_primary_mode()

  All members which belong to the group become primaries.

  For more information, see Section 20.5.1.2, “Changing the Group Mode”

• group_replication_switch_to_single_primary_mode()

  Changes a group running in multi-primary mode to single-primary mode, without the need to stop Group Replication. Must be issued on a member of a replication group running in multi-primary mode. When you change to single-primary mode, strict consistency checks are also disabled on all group members, as required in single-primary mode (group_replication_enforce_update_everywhere_checks=OFF).

  Syntax:

  STRING group_replication_switch_to_single_primary_mode([str])

  Arguments:

  • str: A string containing the UUID of a member of the group which should become the new single primary. Other members of the group become secondaries.

  Return value:

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

  Example:

  SELECT group_replication_switch_to_single_primary_mode(member_uuid);

  For more information, see Section 20.5.1.2, “Changing the Group Mode”