Alex Yurchenko <alexey.yurchenko@codership.com> writes:
From the documentation the purpose of domain ID in GTID is quite clear. But what is the role of server ID?
The role is mainly to ensure uniqueness of GTID when domain_id is not configured correctly. Replication already requires server ID to be unique, so (server_id, sequence number) will be globally unique as long as sequence number is increased locally on each server. Domain id is not required to be unique, in fact it will typically be shared by master and slave. It is a common mistake to do a manual transaction on the slave while transactions are also being done at the same time on the master. Having server_id in the GTID prevents that two different transactions end up with the same GTID. - Kristian.