[debian-mysql] Bug#853972: Bug#853972: mariadb-10.1: upgrading from mysql-5.7 renders old data inaccessible with no option to abort

[Otto Kekäläinen]

2017-02-02 18:19 GMT+02:00 Julian Gilbey <jdg at debian.org>:
> Scenario: I have mysql-server-5.7 installed, and decide to install
> mysql-default-server or mariadb-server or mariadb-server-10.1.
>
> What happens: The mariadb-server-10.1 preinst tells me (lines 114
> onwards):

I think we have here more of a documentation problem than a maintainer
script problem. This behaviour you explain is exactly the same if you
have mysql-5.7 and you install mysql-5.6. There is nothing technically
MariaDB-specific.

But from users point of view of course there is nothing saying that if
you have MySQL 5.7 you should upgrade to MariaDB 10.2 instead, which
is of similar "level" in on-disk format (but not exactly). There is
nothing intuitive there, unlike as in when people intuitively
understand that going from MySQL 5.6 to 5.5 or from MariaDB 10.0 to
5.5 is likely not going to work.

In Stretch we have at play MySQL 5.5, MariaDB 10.0 and MariaDB 10.1.
We should now focus on the interactions of those and think about
MariaDB 10.2 and MySQL 5.7 later. And also MySQL 8.0 even more later,
as currently we don't even know yet what kind of backwards
compatibility it has and what will change in the on-disk format (maybe
again something similar to MySQL 5.7. changing the mysql.user table in
a backwards or sideways incompatible way).