Hello! There is a website, there is a common (main) database (in the General Login Database picture), and there are, say, 2-3 other databases that work with similar (identical) identification data but contain additional fields that are unique only for these databases (in the pictures these are Login Database 1 and L. db 2, marked in red).
This is all located on 2-3 different servers. The user cannot change the identification data through the "General DB". The question is how to synchronize databases in one direction. That is, if there is a change in General, then all these changes are sent or queued for sending (the remote server may be offline) in Log.DB1, Log.DB2, etc.?
I use: ubuntu 16.04 mysql 5.7 MyISAM table type
