Do not attempt to obsolete primary key on log tables
Under some replication scenarios it is necessary to add an auto-increment primary key to log tables.
The log table reconciliation recognises these as 'obsolete' columns and attempt to make them NULLABLE. This is not a big problem in the sense mysql ignores it - but since we upgraded mysql it has become sloooooowwww on upgrade - ie I'm 2 ours inn on our staging server ...