Hi, Aleksey!

On Jan 31, Aleksey Midenkov wrote:
> revision-id: 14c2f90ad08 (versioning-1.0.7-1-g14c2f90ad08)
> parent(s): a8efe7ab1f2
> author: Aleksey Midenkov <midenok@gmail.com>
> committer: Aleksey Midenkov <midenok@gmail.com>
> timestamp: 2018-11-17 16:30:10 +0300
> message:
>
> Idempotent INSERT events for system versioning
>
> Case 1: Rows_log_event::write_row() always overwrite historical row.
>
> Related to MDEV-16370.

I realized that the whole RBR logging of system versioned tables is
wrong.

For an update you log update_row event and write_row event separately
and execute them separately. It allows trivially to manipulate the history.
See a test case attached.

To fix this, the slave should ignore all events that modify the history.
And generate them locally. Say, an update on the master generates
update_row and write_row events. The slave executes update_row event
which updates a current row and this also should generate the historical
row. Then the slave ignores write_row event.

Of course, as an optimization, the master should not generate historical
write_row events, but as my test case shows, they can be forged, so the
slave should ignore them anyway, if they happen to come.

I've created a new https://jira.mariadb.org/browse/MDEV-18432 for that,
let's not have it tied to MDEV-16370.

Regards,
Sergei
Chief Architect MariaDB
and security@mariadb.org