Bug#860970: release-notes: MariaDB vs MySQL section 2.2.3 needs clarifying on how to perform the upgrade

[Paul Gevers]

Package: release-notes
Severity: normal

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Hash: SHA256

I am very glad to see section 2.2.3 in the release-notes. However, I don't
think it is clear from the current text that there will not be any *-server
installed if no precausion is taken (at least, that is my experience and
understanding of the dependencies). mysql-server will be uninstalled during the
upgrade, and only when the default-mysql-server from debian-backports is
installed will the server be automatically replaced by the MariaDB server.

I suggest something like:

MariaDB is now the default MySQL variant in Debian, at version 10.1. The
Stretch release introduces a new mechanism for switching the default variant,
using metapackages created from the mysql-defaults source package. For example,
installing the metapackage default-mysql-server will install
mariadb-server-10.1. For upgrading from jessie, it is recommended to install
this metapackage from the jessie-backports archive so that users who have
mysql-server-5.5 or mysql-server-5.6 will have it removed and replaced
by the MariaDB equivalent. Similarly, installing default-mysql-client will
install mariadb-client-10.1.

Paul

- -- System Information:
Debian Release: 9.0
APT prefers testing-debug
APT policy: (500, 'testing-debug'), (500, 'testing'), (200, 'experimental'), (200, 'testing'), (50, 'experimental'), (50, 'testing'), (1, 'experimental')
Architecture: amd64
(x86_64)

Kernel: Linux 4.9.0-2-amd64 (SMP w/2 CPU cores)
Locale: LANG=en_US.UTF-8, LC_CTYPE=en_US.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash
Init: systemd (via /run/systemd/system)

[Vincent McIntyre]

Hi Paul

If I understand correctly, you are suggesting this change:

MariaDB is now the default MySQL variant in Debian, at version 10.1.
The Stretch release introduces a new mechanism for switching the
default variant, using metapackages created from the
mysql-defaults source package.
For example, installing the metapackage
default-mysql-server will install
mariadb-server-10.1.
- Users who had
+ For upgrading from jessie, it is recommended to install
+ this metapackage from the jessie-backports archive so that
+ users who have
mysql-server-5.5 or mysql-server-5.6 will have it
removed and replaced by the MariaDB equivalent.
Similarly, installing default-mysql-client will install
mariadb-client-10.1.

I don't think the release team want upgrades to depend on backports,
so I don't that's a viable option here.

But let's go back a step - you're saying that
if: you have a jessie system with mysql-server-5.x
and you dist-upgrade,
without explicitly installing default-mysql-server
then: mysql-server-5.x gets uninstalled
and no mariadb-server-* package gets installed ?

If correct, that's a big problem.

What the text is trying to tell people to do is to dist-upgrade,
then install default-mysql-server. That second action should
initiate the uninstall of mysql-server-5.x and then install
mariadb-server-10.1. Is that what you took from the text?
If not, can you think of a way to make it clearer?

Cheers
Vince

[Paul Gevers]

Hi Vincent,

Thanks for trying to improve my proposal, I wasn't quite happy with it
either.

Post by Vincent McIntyre
I don't think the release team want upgrades to depend on backports,
so I don't that's a viable option here.

I had the problem with this suggestion as well, but I didn't understand
the MySQL/MariaDB upgrade path better than that.

Post by Vincent McIntyre
But let's go back a step - you're saying that
if: you have a jessie system with mysql-server-5.x
and you dist-upgrade,
without explicitly installing default-mysql-server
then: mysql-server-5.x gets uninstalled
and no mariadb-server-* package gets installed ?
If correct, that's a big problem.

I believe what you state here is true, as that is what I experienced on
my upgrade. When I upgraded, there wasn't mentioning of this yet (or I
didn't spot it) and it was exactly the reason why I went to look in the
release notes to provide info. The info that I found was missing
essential details or the right tone to trigger the system administrator
into the right actions.

Post by Vincent McIntyre
What the text is trying to tell people to do is to dist-upgrade,
then install default-mysql-server. That second action should
initiate the uninstall of mysql-server-5.x and then install
mariadb-server-10.1. Is that what you took from the text?
If not, can you think of a way to make it clearer?

I believe the mysql-server-5.x is already removed during the
dist-upgrade. At least that is what happened on my system. But maybe you
mean 'apt upgrade' (without dist-). If that is what you mean (and I
guess that should work), the text is by far not clear.

So something like (fully untested):
MariaDB is now the default MySQL variant in Debian, at version 10.1.
The Stretch release introduces a new mechanism for switching the
default variant, using metapackages created from the
mysql-defaults source package.
For example, installing the metapackage
default-mysql-server will install
mariadb-server-10.1.
- Users who had
+ For upgrades from jessie, it is recommended to install
+ this metapackage after 'apt upgrade', but before 'apt dist-upgrade'
+ so that users who have
mysql-server-5.5 or mysql-server-5.6 will have it
removed and replaced by the MariaDB equivalent.
+ If no precaution is taken, mysql-server-5.x will be removed *without*
+ a replacement being installed.
Similarly, installing default-mysql-client will install
mariadb-client-10.1.

Paul

By the way, I think it should be 'meta-package' or 'meta package'
instead of 'metapackage' in correct English, but I am no native speaker.

[Debian Bug Tracking System]

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and subject line Re: [debian-mysql] FWD [Re: Bug#860970: release-notes: MariaDB vs MySQL section 2.2.3 needs clarifying on how to perform the upgrade]
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regarding release-notes: MariaDB vs MySQL section 2.2.3 needs clarifying on how to perform the upgrade
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