[DISCUSS] db changes on the 4.0.x release line

[Prasanna Santhanam <ts...@apache.org>]

So this is broken off from the thread on Support Timelines for the
4.0.x group of releases:

The issue is regarding upgrades. With the introduction of the
DatabaseCreator I notice that we don't have to do any sort of changes
to the baseline schema of 4.0. This is a great improvement but it only
is enforced on the 4.1,4.2 etc releases.

We have the 4.0.x release line for 4.0.1, 4.0.2 etc. There currently
is no upgrade path from this release line to the 4.1,4.2 release line.
The 4.0 branch also uses the older way of doing schema changes
(create-schema.sql, upgradeXtoY.sql) which conflicts with the way the
DbCreator works. That will have problems in upgrades of deployments
going from 4.0.x-incubating to anything in 4.1,4.2.

How should this be tackled? 

Since there have been few schema changes (only one) in
4.0.1-incubating it's probably best to port the DbCreator back to 4.0
as well? Rohit suggested that the 4.0 branch not add db changes but I
think it's better enforced than left as a rule.

Thoughts?

-- 
Prasanna.,

RE: [DISCUSS] db changes on the 4.0.x release line

[Koushik Das <ko...@citrix.com>]

Ideally the upgrade path from any point release like 4.0.x should always run 4.0 to 4.1 upgrade script. This upgrade script should make the changes only if it is not already present. I came across [1] which shows how to do such checks but its only applicable for mysql 5 and above. For lower versions some special handling may be required for upgrades.

-Koushik

[1] http://www.cryer.co.uk/brian/mysql/howto_add_column_unless_exists.htm


> -----Original Message-----
> From: David Nalley [mailto:david@gnsa.us]
> Sent: Tuesday, March 05, 2013 10:34 PM
> To: cloudstack-dev@incubator.apache.org
> Subject: Re: [DISCUSS] db changes on the 4.0.x release line
> 
> On Tue, Mar 5, 2013 at 11:54 AM, Prasanna Santhanam <ts...@apache.org>
> wrote:
> > So this is broken off from the thread on Support Timelines for the
> > 4.0.x group of releases:
> >
> > The issue is regarding upgrades. With the introduction of the
> > DatabaseCreator I notice that we don't have to do any sort of changes
> > to the baseline schema of 4.0. This is a great improvement but it only
> > is enforced on the 4.1,4.2 etc releases.
> >
> > We have the 4.0.x release line for 4.0.1, 4.0.2 etc. There currently
> > is no upgrade path from this release line to the 4.1,4.2 release line.
> > The 4.0 branch also uses the older way of doing schema changes
> > (create-schema.sql, upgradeXtoY.sql) which conflicts with the way the
> > DbCreator works. That will have problems in upgrades of deployments
> > going from 4.0.x-incubating to anything in 4.1,4.2.
> >
> > How should this be tackled?
> >
> > Since there have been few schema changes (only one) in
> > 4.0.1-incubating it's probably best to port the DbCreator back to 4.0
> > as well? Rohit suggested that the 4.0 branch not add db changes but I
> > think it's better enforced than left as a rule.
> >
> 
> So I personally am a bit irked that 4.0.1 needed a schema change, but its our
> own fault, and usage simply didn't work without it. Ideally point releases
> would not have a frozen schema; but it clearly it isn't an option if we ship a
> release with a broken schema.
> 
> Upgrades are non-negotiable - they must work. Stranding a user on any
> given release without an option to upgrade is not acceptable.
> 
> I don't personally think backporting dbcreator into 4.0 is the right answer. If
> we can't get dbcreator to smoothly handle upgrades, perhaps we need to
> revisit it. Handling upgrades smoothly is a requirement for release IMO.
> 
> --David

Re: [DISCUSS] db changes on the 4.0.x release line

[David Nalley <da...@gnsa.us>]

On Tue, Mar 5, 2013 at 11:54 AM, Prasanna Santhanam <ts...@apache.org> wrote:
> So this is broken off from the thread on Support Timelines for the
> 4.0.x group of releases:
>
> The issue is regarding upgrades. With the introduction of the
> DatabaseCreator I notice that we don't have to do any sort of changes
> to the baseline schema of 4.0. This is a great improvement but it only
> is enforced on the 4.1,4.2 etc releases.
>
> We have the 4.0.x release line for 4.0.1, 4.0.2 etc. There currently
> is no upgrade path from this release line to the 4.1,4.2 release line.
> The 4.0 branch also uses the older way of doing schema changes
> (create-schema.sql, upgradeXtoY.sql) which conflicts with the way the
> DbCreator works. That will have problems in upgrades of deployments
> going from 4.0.x-incubating to anything in 4.1,4.2.
>
> How should this be tackled?
>
> Since there have been few schema changes (only one) in
> 4.0.1-incubating it's probably best to port the DbCreator back to 4.0
> as well? Rohit suggested that the 4.0 branch not add db changes but I
> think it's better enforced than left as a rule.
>

So I personally am a bit irked that 4.0.1 needed a schema change, but
its our own fault, and usage simply didn't work without it. Ideally
point releases would not have a frozen schema; but it clearly it isn't
an option if we ship a release with a broken schema.

Upgrades are non-negotiable - they must work. Stranding a user on any
given release without an option to upgrade is not acceptable.

I don't personally think backporting dbcreator into 4.0 is the right
answer. If we can't get dbcreator to smoothly handle upgrades, perhaps
we need to revisit it. Handling upgrades smoothly is a requirement for
release IMO.

--David