On 29-12-15 14:46, Daan Hoogland wrote:
Wido, Rafael,
I like the date-format but then of course CCYY-MM-DD. I can still think
of
ways to screw up that (or the plain int;)
20151229 is a valid integer which you can simply use to compare with.
100, 101, 102 or 20151229, 20160103, 20160104, I don't care that much.
My point is that the database version should be separated from the code
base.
Wido
On Tue, Dec 29, 2015 at 1:40 PM, Rafael Weingärtner <
rafaelweingart...@gmail.com> wrote:
Wido, that is true, you are right; the naming on upgrade routines can
use a
numeric value independent of the number of the version. The numeric
value
can be a simple integer that is incremented each routine that is added
or a
time stamp when the routine was added. The point is that we would have
to
link a version to a number. That would enable us to use flywaydb.
To use that approach I think we might need to break compatibility as
you
pointed out earlier, but I believe that the benefits of an improved
way
to
manage upgrade routines will compensate by the breaking of
compatibility.
On Tue, Dec 29, 2015 at 10:25 AM, Wido den Hollander <w...@widodh.nl>
wrote:
On 29-12-15 13:21, Rafael Weingärtner wrote:
I got your point Daan.
Well, and if we linked a version of ACS with a time stamp in the
format
of
DD.MM.YYYY?
In that case you could also say.
ACS 4.6.0 == db ver X
You don't have to say ver >= X, you can also say ver = X.
We could then use the time stamp in the same format to name upgrade
routines. This way the idea of running all of the routines in
between
version during upgrades could be applied.
Same goes for giving all database changes a simple numeric int which
keeps incrementing each time a change is applied ;)
Wido
On Tue, Dec 29, 2015 at 10:03 AM, Daan Hoogland <
daan.hoogl...@gmail.com
wrote:
Rafael,
On Tue, Dec 29, 2015 at 12:22 PM, Rafael Weingärtner <
rafaelweingart...@gmail.com> wrote:
Thanks, Daan and Wido for your contributions, I will discuss them
as
follows.
Daan, about the idea of per commit upgrades. Do you mean that we
separate
each change in the database that is introduced by PRs/Commits in a
different file (routine upgrade) per ACS version?
So we would have, V_480_A.sql (for a PR),V_480_B.sql (for another
PR)
and
so forth
If that is the case, we can achieve that using a simple convention
naming
as I suggested. Each developer when she/he needs to change or add
something
in the database creates an upgrade routine separately and gives it
an
execution order to be taken by Flywaydb. I think that could help
RMs
to
track and isolate the problem, right?
Yes, with one little caveat. We do not know in what version a
feature/PR
will end up at the time of implementing, so a name containing the
version
would not be ideal.
Hi Wido, now I understand your example.
I understand your worry about upgrade paths, and that is the
point I
want
to discuss and solve. In your example, if we release a 4.6.0 and
later
a
4.5.3. You said that there would be no upgrade path from 4.5.3 to
4.6.0.
Well, today that is what happens. However, if we change the
technology
we
use to upgrade the database (using a tool such as Flywaydb) and if
we
define a standard to create upgrade routines that would not be a
problem.
As I have written in my first email, to go from a version to
another
we
should be able to run all of the upgrade routines in between them
(including the upgrade routine of the goal version). Therefore, if
we
release a version 4.6.0, and then 4.5.3, if someone upgrades to
4.5.3
from
any other version, and then wants to upgrade to 4.6.0, that would
not
be
a
problem, it would be a metter of running only the routine upgrade
of
4.6.0
version. We do not need to explicitly create upgrade paths. They
should
be
implicit by our upgrade conventions.
About creating versions of the code that rely on some version of
the
database. I do not like much because of compatibility issues that
might
arise. For instance, let’s say version X of ACS depends on version
=Y
of
the database. If I upgrade the database to version Y + 1 or +2,
the
same
ACS version has to keep running nice and shiny. My worry is that
may
bring
some complications, such as to remove columns that cease to be
used
or
data
structure that we might want to improve.
I normally see that the database version and the code base are
tied
in
a
mapping 1 to 1. Maybe I am having troubles identifying the
benefits
of
that
change.
Thanks for your time ;)
On Tue, Dec 29, 2015 at 8:15 AM, Wido den Hollander <
w...@widodh.nl
wrote:
On 28-12-15 21:34, Rafael Weingärtner wrote:
Hi Wido, Rohit,
I have just read the feature suggestion.
Wido, I am not trying to complicate things, quite the opposite,
I
just
illustrate a simple thing that can happen and is happening; I
just
pointed
how it can be easily solved.
About the release of .Z, releases more constant and others, I do
not
want
to mix topics. Let’s keep this thread strict to discuss database
upgrades.
I do not want to start the release discussion, but what I meant
is
that
we try to find a technical solution to something which might be
solved
easier by just changing the way we release.
4.6.0 is released and afterwards 4.5.3 is released. How does
somebody
upgrade from 4.5.3 to 4.6.0? He can't, since the 4.6.0 code
doesn't
support that path.
So my idea is to split the database version from the code
version.
The code requires database version >= X and during boot it simply
checks
that.
The database migration tool can indeed do the DB migration, it
doesn't
have to be the mgmt server who does the upgrade.
Now, about the FS. I agree with Rohit that we should have only
one
way
of
managing database upgrades and creation. I just do not like the
idea
of
creating a tool that work as a wrapper on frameworks/tools such
as
flywaydb. I think that those frameworks already work pretty good
as
they
are; and, I would rather maintain configurations than some
wrapper
code.
I personally like the way ACS works during upgrades (I just do
not
like
the
code itself and how things are structured), as a system
administrator I
like to change the version in the
“/etc/apt/sources.list.d/cloudstack.list”
and use the "apt-get" "update" and "install" from the command
line. I
do
not see the need to add another tool that is just a wrapper to
the
mix.
If
I update ACS code to 4.7.0, why would I let the database schema
in
an
older
version? And if we want version DB schemas and application code
separately
maintaining somehow compatibility between them, which would
bring
a
whole
other level of complexity to the code; I think we should avoid
that.
The flywaydb can be easily integrated with everything we have
now;
we
could
have a maven profile for developers and integrate it in ACS
bootstrap
using
its API as a Spring bean. Therefore, we could remove the current
“DatabaseUpgradeChecker “, “DbUpgrade” and other classes that
aim
to
do
that. We could even add the creation of the schema into the
first
time
it
boots using flywaydb and retire the “cloudstack-setup-database”
script,
or
at least make it less complicated, using it just to configure
the
database
URL and users.
The point is that to use Flywaydb we would have to agree upon a
convention
on creating routines (java and SQL) to execute upgrades.
Moreover,
using
a
tool such as Flywaydb we do not need to worry about upgrade
paths.
As I
wrote in the email I used to start this thread, the upgrade has
to
be
straightforward, to go to a version we have to run all of the
upgrade
routines between the current version until the desired one. Our
job
is
to
create upgrade routines that work and name them properly, the
job
of
the
tool is to check the current version, the desired one, the
upgrades
that
it
needs to run and execute everything properly.
Yes, indeed. I just wanted to start the discussion if we
shouldn't
version the database differently from the code.
Additionally, I do not see the need to break compatibility as
Rohit
suggested in the FS; in my opinion, everything we have up today
can
be
migrated to the new structure I proposed. If we use a tool such
as
Flywaydb, I even volunteered for that. The only thing we have to
discuss
and agree upon is the naming conventions for upgrades routines,
where
to
put them and the configurations for flywaydb.
Thanks for your contribution and time.
On Mon, Dec 28, 2015 at 2:10 PM, Rohit Yadav <
rohit.ya...@shapeblue.com>
wrote:
Hi Rafael and Wido,
Thanks for starting a conversation in this regard, I could not
pursue
the
Chimp tool due to other $dayjob work though it’s good to see
some
discussion has started again. Hope we’ll solve this in 2016.
In my opinion, we will need to first separate the database
init/migration
tooling away from mgmt server (right now the mgmt server does
db
migrations
when it starts and there is a code/db version mismatch) and
secondly
make
sure that we’re using the same code/tool to deploy database
(right
now,
users use the cloudstack-setup-database python tool while
developer
use
the
maven/java DatabaseCreator activated by the -Ddeploydb flag).
After we’ve addressed these two issues we can look into how we
can
support
minor releases workflow (or decide to do something else, like
not
support
.Z releases like Wido mentioned), and see if we can or want to
use
any
existing migration tool or write a wrapper tool “chimp” that
uses
existing
tools (some of those are mentioned in the Chimp FS like
flywaydb
etc).
For
allowing users to go back and forth from a db schema/version,
we’ll
also
need some new DB migration
conventions/versioning/rules/static-checking,
and how developer need to write such paths (forward and
reverse)
etc.
The best approach I figured at the time was to decide that
we’ll
use
the
previous db upgrade path mechanism till a certain CloudStack
version
(say
4.8.0) and after that we’ll use the new approach or tooling to
upgrade/downgrade DB schemas (thereby retiring away from the
old
DB
upgrade
path mess).
[image: ShapeBlue] <http://www.shapeblue.com> Rohit Yadav
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