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Comment by mrtron | Hacker News Reader

Am I the only one left who finds south more trouble than it is worth?

The only one? No, I'm sure not. In the vast minority? I'd suspect so :)

South is pretty obtuse to learn and definitely has it's warts and issues, which Andrew seems well aware of and wants to fix so check out the kickstarter link below!

That said, our project has over three hundred tables, a couple thousand migrations, and I've been very happy with it compared to the systems I've rolled myself in the past. I'm certainly unaware of an alternative that holds a candle to it, assuming Django's ORM.

South can be troublesome, but what's your alternative? never make changes to your schema? do it painstakingly by hand from the psql command line? just suck it up and use South, warts and all. its still really good, even though its not perfect.

...what's your alternative?

Write SQL and interact with your RDBMS directly?

that is not a viable practice over the long run. the entire point of using a migrations tool is so you can migrate the schema and the data forwards and backwards automatically and consistently every time. attempting to do that with raw SQL scripts is a disaster waiting to happen. its so bad that the entire idea of a migration tool was invented to solve this problem.

so I ask again: what's your alternative (given that avoiding raw SQL scripts is the problem you're trying to solve)?

I'm getting sucked into an argument I don't really care about because I actually like South and use it in production for some things.

But I mean idempotent SQL takes care of the vast majority of all this stuff you mentioned. Write your SQL properly and it doesn't matter whether or not it's been applied before.

I don't know about postgres offhand, but there aren't idempotent solutions to some DDL operations in mysql. (alter table add column, off the top of my head)

Yeah in Postgres you can check for the existence of a column in a table. If it exists/doesn't exist you can drop/add the column. Obviously "ALTER TABLE x ADD COLUMN y" isn't idempotent, but the whole SQL statement around it can be idempotent.

You still need a system for tracking which changes have been applied to your database and for distributing the changes to the rest of your team.

Even if you don't use South's automatic migration generation, its database-independent schema modification api [1], dependency tracking, and tracking of which migrations have been run, are useful and necessary. In fact, the automatic generation of migrations is an optional feature of South that was not in it when first released.

When you need to write SQL and interact with your database directly, using `db.execute` inside a South migration is a nice way to do it.

[1]: http://south.readthedocs.org/en/latest/databaseapi.html

I've been on a project that was doing exactly this. It's a giant PITA and we found ourselves slowly implementing something that looks a lot like South in order to mitigate all the problems we encountered. So we dropped this approach entirely and just used South. With a half decent migration strategy it's so much more robust than messing around with SQL. Unless there are specific edge cases that a migration tool can't deal with, use one.

Maybe if you're working on your own. If you're in a team (where each member has her own local DB) and multiple environments for testing, staging, preproduction etc. I'd say you're going to want some sort of scripted migration.

I came to Django & South after using ActiveRecord and Rails migrations for years, and it drove me nuts. Not trying to cause a big argument, but why the big push in the Python community to model database tables via object properties/fields? I seem to recall SqlAlchemy does something similar.

From 'The Zen of Python' - Explicit is better than implicit.

Automatically generating properties after querying the database is seen as unpythonic. PyLint and some IDEs/editors will not be happy if you try.

DataMapper 1 does the same. It does make sense if you're worried about changes to your database schema spontaneously breaking previously working code.

No, I get that part. I'm talking more about building a database from models. It seems like these tools are designed to build the database scheme from the object models, which to me is just as bad as building the objects from the schema.

Ideally, we should use the declarative style of Django models and SqlAlchemy on the object, along with the scheme generation tools of Rails migrations.

My workflow is to only add south to the project when required. To begin with I use a bash script which trashes and rebuilds the DB each time I wish to. Data which needs to survive this gets dumped to fixtures (using another bash script).

I totally agree with you. I just export the SQL and see what tables need to change.

I'm working on a tool for better schema migrations as well. Currently it only supports MySQL but more RDBMS's coming soon: http://devjoist.com

Good luck, but you may want to reconsider. Andrew Godwin (author of South and Django contributor) is building a new version directly into Django core.

http://www.kickstarter.com/projects/andrewgodwin/schema-migr...

DevJoist is language agnostic so I think there will be a need for it regardless of what happens with Python. I'm actually a backer of Andrew's kickstarter :)

don't be discouraged. a solid, open-source solution that is language/platform agnostic is valuable.

When I started using South, I was much in awe and loved its ease. But as time passed migrations became completed and south soon came to its knees.

I find that generally, when this happens it's due to a bad / non-existant migration policy (it's just as important as your branching strategy to keep migrations solid). Migrations should be able to rebuild an entire database from scratch. If it can't then the migrations have been screwed up.

i think it is the best solution out there right now ... someone had a kickstarter recently to replace it, but I can't seem to find that info via google right now ...

I believe you're thinking of Andrew Godwin's schema migration kickstarter: http://www.kickstarter.com/projects/andrewgodwin/schema-migr...

yep - that is what i was looking for - thanks

Andrew Godwin had that Kickstarter and he is the creator of South. Here is the link http://www.kickstarter.com/projects/andrewgodwin/schema-migr...

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