MySQL Shell 8.4
When you are using an instance as part of an InnoDB Cluster,
the auto_increment_increment
and auto_increment_offset
variables are configured to avoid the possibility of auto
increment collisions for multi-primary clusters up to a size of
9 (the maximum supported size of a Group Replication group). The
logic used to configure these variables can be summarized as:
If the group is running in single-primary mode, then set
auto_increment_increment to
1 and auto_increment_offset
to 2.
If the group is running in multi-primary mode, then when the
cluster has 7 instances or less set
auto_increment_increment to
7 and auto_increment_offset
to 1 + server_id % 7. If a
multi-primary cluster has 8 or more instances set
auto_increment_increment to
the number of instances and
auto_increment_offset
to 1 + server_id % the
number of instances.