Re: I can't decide on a migration framework

[Ben Davis]

Thanks Russ! Your insight is greatly appreciated.

On Mon, Mar 9, 2009 at 8:58 PM, Russell Keith-Magee
wrote:

>
> On Tue, Mar 10, 2009 at 8:23 AM, Ben Davis  wrote:
> > are you saying that django-evolution does not support migrating between
> > "versions"  (ie up and down)?
>
> Django Evolution doesn't currently support down-migrations. This isn't
> due to any particular technical limitation - it just hasn't been
> implemented.
>
> > I'm mostly trying to get an idea of what migration frameworks django
> > devopers use, and why they prefer it.
>
> At the moment, this is still an emerging field. All of the leading
> candidates are works-in-progress, so there isn't any single framework
> you can point at and conclusively say "use this one". For what it's
> worth, a recent survey on the This Week in Django [1] gave Django
> Evolution a slight edge over South in the popularity stakes, but both
> frameworks came second to "Raw sql".
>
> [1] http://thisweekindjango.com/twid/episode/47/this-week-in-django-47/
>
> I'm biased, since I'm the developer of Django Evolution. Obviously, I
> think Evolution is pretty good :-) However, my Django and other life
> commitments mean I haven't been able to give it the attention it has
> needed lately. There are a couple of outstanding bugs, and plenty of
> features I would like to add.
>
> Historically, Django Evolution has had more "smarts" - the evolution
> hinting process is more advanced under Evolution than it is under
> South. However, there are some edge cases where this hinting process
> goes wrong, and it can be difficult to recover from these situations.
> There is also a known gap in the support for MySQL, due to some of the
> eccentricities of MySQL schema modification syntax.
>
> South is another strong candidate. Andrew is a smart guy, and he's
> been making some great advances in South over the last few months.
> Reading between the lines, I believe that Evolution-like hinting
> features are on his to-do list in the near future. I haven't used
> South in anger myself, but I know plenty of people that do - I doubt
> you would be disappointed if you chose to use it.
>
> dbmigrations is a pretty good 'bare bones' framework - it manages your
> SQL migrations, but not much else. However, if that is all you need,
> it may be a good choice.
>
> This isn't a complete list, either. Migration frameworks keep popping
> up all the time. The only really helpful advice I can give is to try a
> few, and see what suits your needs.
>
> Yours,
> Russ Magee %-)
>
> >
>

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Re: I can't decide on a migration framework

[Russell Keith-Magee]

On Tue, Mar 10, 2009 at 8:23 AM, Ben Davis  wrote:
> are you saying that django-evolution does not support migrating between
> "versions"  (ie up and down)?

Django Evolution doesn't currently support down-migrations. This isn't
due to any particular technical limitation - it just hasn't been
implemented.

> I'm mostly trying to get an idea of what migration frameworks django
> devopers use, and why they prefer it.

At the moment, this is still an emerging field. All of the leading
candidates are works-in-progress, so there isn't any single framework
you can point at and conclusively say "use this one". For what it's
worth, a recent survey on the This Week in Django [1] gave Django
Evolution a slight edge over South in the popularity stakes, but both
frameworks came second to "Raw sql".

[1] http://thisweekindjango.com/twid/episode/47/this-week-in-django-47/

I'm biased, since I'm the developer of Django Evolution. Obviously, I
think Evolution is pretty good :-) However, my Django and other life
commitments mean I haven't been able to give it the attention it has
needed lately. There are a couple of outstanding bugs, and plenty of
features I would like to add.

Historically, Django Evolution has had more "smarts" - the evolution
hinting process is more advanced under Evolution than it is under
South. However, there are some edge cases where this hinting process
goes wrong, and it can be difficult to recover from these situations.
There is also a known gap in the support for MySQL, due to some of the
eccentricities of MySQL schema modification syntax.

South is another strong candidate. Andrew is a smart guy, and he's
been making some great advances in South over the last few months.
Reading between the lines, I believe that Evolution-like hinting
features are on his to-do list in the near future. I haven't used
South in anger myself, but I know plenty of people that do - I doubt
you would be disappointed if you chose to use it.

dbmigrations is a pretty good 'bare bones' framework - it manages your
SQL migrations, but not much else. However, if that is all you need,
it may be a good choice.

This isn't a complete list, either. Migration frameworks keep popping
up all the time. The only really helpful advice I can give is to try a
few, and see what suits your needs.

Yours,
Russ Magee %-)

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Re: I can't decide on a migration framework

[Kenneth Gonsalves]

On Tuesday 10 March 2009 04:53:25 Ben Davis wrote:
> are you saying that django-evolution does not support migrating between
> "versions"  (ie up and down)?

no
>
> I'm mostly trying to get an idea of what migration frameworks django
> devopers use, and why they prefer it.

most do not use frameworks for migration - it is done manually. 

-- 
regards
kg
http://lawgon.livejournal.com

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Re: I can't decide on a migration framework

[Ben Davis]

are you saying that django-evolution does not support migrating between
"versions"  (ie up and down)?

I'm mostly trying to get an idea of what migration frameworks django
devopers use, and why they prefer it.

On Mar 7, 2009 5:31 PM, "Briel"  wrote:


A fixed migration is the code run to get from one step to another.
Migrations uses the, maybe at some point you needed to add an extra
table to the db. Then you could write a migration that would add the
table if you wanted to progress or delete the table if you wanted to
get back. You would have that list with app and when you install the
app elsewhere you could choose at which point in the migration history
you wanted your database in. Maybe for some testing you needed the
database like it was at some point. Evolution works differently, it
looks at the db and compares it to the models and the try to make the
changes needed when you run syncdb. So in order to controll evolutions
you would need to change to model fields.

On 7 Mar., 23:59, Ben Davis  wrote: > I've been
looking into both the "South"...
> claimsto have started the

> project out of frustrations with django-evolution.  I've > read those
points, and having a really ...

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Re: I can't decide on a migration framework

[Briel]

A fixed migration is the code run to get from one step to another.
Migrations uses the, maybe at some point you needed to add an extra
table to the db. Then you could write a migration that would add the
table if you wanted to progress or delete the table if you wanted to
get back. You would have that list with app and when you install the
app elsewhere you could choose at which point in the migration history
you wanted your database in. Maybe for some testing you needed the
database like it was at some point. Evolution works differently, it
looks at the db and compares it to the models and the try to make the
changes needed when you run syncdb. So in order to controll evolutions
you would need to change to model fields.

On 7 Mar., 23:59, Ben Davis  wrote:
> I've been looking into both the "South" and "django-evolution" migration
> frameworks.   There are things I like about both of them, although I'm
> leaning towards django-evolution.
>
> The thing I like about django-evolution is that migrations are described in
> the same "language" as your model,  that is,  instead of adding/removing
> tables & columns,  we're adding/removing models and fields,  which is (I
> believe) the way it should be.  I don't feel like "create_table()" is any
> different from SQL's  "CREATE TABLE".
>
> However,  the author of South
> claimsto have started the
> project out of frustrations with django-evolution.  I've
> read those points, and having a really difficult time understanding what
> they really mean.  What do they mean by migartions not being "fixed in the
> codebase",  and "fixed migrations are all run when an app is first
> installed" ?   What exactly are "fixed migrations" anyways?   I'd love to
> understand these points as I don't want to regret choosing django-evolution.
>
> I haven't looked into dmigrations that much, but if anyone has any input on
> that I'm all ears.
>
>  Thanks!!
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