[Bug 1725222] Re: do-release-upgrade from Ubuntu 14.04 to 16.04.1 performs unsupported upgrade from MySQL 5.5 to 5.7

[Robie Basak]

> Seems they identified the issue causing the upgrade to fail:
https://support.plesk.com/hc/en-us/articles/115003430813#_=_

So it looks like the configuration option
innodb_additional_mem_pool_size was valid in MySQL 5.5 but is no longer
valid in MySQL 5.7? AFAICT, that configuration option was not shipped in
any packaging previously. Is the problem that for users who have
customised their system configurations with this option (or for example
some third party tool has done it), a subsequent release upgrade to 5.7
will fail?

See bug 1571865. Upstream does not provide a script which can
automatically convert every single possible configuration customisation
in MySQL 5.5 with an updated equivalent version in MySQL 5.7. So
distributions cannot reasonably be expected to be able to provide such
an automated upgrade path either. This is standard behaviour across all
distributions I believe. Distributions allow you (or a third party
working on your behalf) to customise your installations to the extreme.
However, there is no practical automatic upgrade path that works in all
cases and can be provided when upstream semantics change in a release
upgrade.

So I cannot consider this to really be a bug in MySQL packaging.

If, separately, you want to provide a smoother upgrade path in a
maintainer script for a specific customisation, then we'll happily
accept that patch. Providing that the patch can be shown to likely not
make anything worse in any possible use case. If you want to do this,
then please file a specific bug for the specific customisation (or set
of customisations) upgrade path you want to fix. Please don't use a
generic "it doesn't work" bug like this one has become as that just
results in confusion with all of the "me too" people involved in this
bug who may be affected by the general issue but not your particular and
specific customisation.

** Changed in: mysql-5.7 (Ubuntu)
       Status: New => Invalid

** Changed in: ubuntu-release-upgrader (Ubuntu)
       Status: New => Invalid

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https://bugs.launchpad.net/bugs/1725222

Title:
  do-release-upgrade from Ubuntu 14.04 to 16.04.1 performs unsupported
  upgrade from MySQL 5.5 to 5.7

Status in Ubuntu Server Guide:
  Invalid
Status in mysql-5.7 package in Ubuntu:
  Invalid
Status in ubuntu-release-upgrader package in Ubuntu:
  Invalid

Bug description:
  Updating from Ubuntu 14.04 to Ubuntu 16.04.1 using do-release-upgrade
  will cause troubles because MySQL is upgraded from 5.5 to 5.7, that is
  an unsupported update path, as per MySQL official documentation.

  Your script should do these pre-checks and prevent upgrade, or
  automatically solve the issue before applying upgrade.

  PS: the solution is to upgrade MySQL in two steps, first from 5.5 to
  5.6 then from 5.6 to 5.7.

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