Skip to main content

SQLAlchemy-Migrate for dummies

I'm gave sqlalchemy-migrate a try today. I like it, and I'm going to keep using it. The one downside is that it's a bit hard to find "the least you need to know" in the documentation, especially if you lean old-school like me and prefer to write your upgrade scripts in raw sql. So here's my stab at it.

Create a "repository" for upgrade scripts:

migrate create path/to/upgradescripts "comment"

Create your manage script. If you have development/production dbs with different connection urls, create two scripts with the same repository but different urls:

migrate manage dbmanage.py --repository=path/to/upgradescripts --url=db-connection-url

For each database, create the Migrate metadata (a migrate_version table):

./dbmanage.py version_control

Create an upgrade script. This will create a script [next version number]-[database type]-upgrade.sql in the "versions" subdirectory of your "repository." That's all, so you could certainly do this by hand if you prefer, but letting the script do it is less error-prone:

./dbmanage.py script_sql sqlite

Edit the script.

For each database, apply the upgrade:

./dbmanage.py upgrade

Repeat the script/upgrade process as needed. That's it! Everything else is optional!

(What this gives you is a process where all your developers can have their own local database for development, and all they have to do is "svn up; ./dbmanage.py upgrade" without having to worry about which upgrade scripts have been applied or not.)

Comments

Tim Lesher said…
Maybe it's just me, but every time I look at the migrate command line, I see "dbdamage.py" rather then "dbmanage.py"...
Anonymous said…
It's hard to find a good tutorial about using migrate, though. Especially if you want to use it from the Python app itself.

Popular posts from this blog

Python at Mozy.com

At my day job, I write code for a company called Berkeley Data Systems. (They found me through this blog, actually. It's been a good place to work.) Our first product is free online backup at mozy.com . Our second beta release was yesterday; the obvious problems have been fixed, so I feel reasonably good about blogging about it. Our back end, which is the most algorithmically complex part -- as opposed to fighting-Microsoft-APIs complex, as we have to in our desktop client -- is 90% in python with one C extension for speed. We (well, they, since I wasn't at the company at that point) initially chose Python for speed of development, and it's definitely fulfilled that expectation. (It's also lived up to its reputation for readability, in that the Python code has had 3 different developers -- in serial -- with very quick ramp-ups in each case. Python's succinctness and and one-obvious-way-to-do-it philosophy played a big part in this.) If you try it out, pleas...

A week of Windows Subsystem for Linux

I first experimented with WSL2 as a daily development environment two years ago. Things were still pretty rough around the edges, especially with JetBrains' IDEs, and I ended up buying a dedicated Linux workstation so I wouldn't have to deal with the pain.  Unfortunately, the Linux box developed a heat management problem, and simultaneously I found myself needing a beefier GPU than it had for working on multi-vector encoding , so I decided to give WSL2 another try. Here's some of the highlights and lowlights. TLDR, it's working well enough that I'm probably going to continue using it as my primary development machine going forward. The Good NVIDIA CUDA drivers just work. I was blown away that I ran conda install cuda -c nvidia and it worked the first try. No farting around with Linux kernel header versions or arcane errors from nvidia-smi. It just worked, including with PyTorch. JetBrains products work a lot better now in remote development mod...

A review of 6 Python IDEs

(March 2006: you may also be interested the updated review I did for PyCon -- http://spyced.blogspot.com/2006/02/pycon-python-ide-review.html .) For September's meeting, the Utah Python User Group hosted an IDE shootout. 5 presenters reviewed 6 IDEs: PyDev 0.9.8.1 Eric3 3.7.1 Boa Constructor 0.4.4 BlackAdder 1.1 Komodo 3.1 Wing IDE 2.0.3 (The windows version was tested for all but Eric3, which was tested on Linux. Eric3 is based on Qt, which basically means you can't run it on Windows unless you've shelled out $$$ for a commerical Qt license, since there is no GPL version of Qt for Windows. Yes, there's Qt Free , but that's not exactly production-ready software.) Perhaps the most notable IDEs not included are SPE and DrPython. Alas, nobody had time to review these, but if you're looking for a free IDE perhaps you should include these in your search, because PyDev was the only one of the 3 free ones that we'd consider using. And if you aren...