MySQL Master-Slave Replication additional columns on slave are being reset to their default value I have setup a master-slave replication in MySql. I have added additional columns to one of the tables in the slave database in order to store some additional information, which should not be an issue, since it is inline with the following rules: https://dev.mysql.com/doc/refman/5.7/en/replication-features-differing-tables.html

Now the issue that I am facing is that when I fill these additional columns, the data I fill them with is being lost once replication happens. By lost I mean that the data in these additional columns are reset to their default value.

Should this happen? I have not found anywhere where this behavior is documented and I can't understand why this is happening.

Does anybody can shed any light on this?

Thank you very much.
If the table definitions are different, you are asking for trouble and need to be careful.

In particular, if replication is using Row Based Replication, I suspect the missing columns would get defaults, but I would not trust it.

If you are writing to the Slave, you are asking for trouble.

But this may be a workaround -- instead of having extra columns, have an extra table for the extra columns.  The two table would have the the same PRIMARY KEY, except that the extra table would not say AUTO_INCREMENT.