Archive for the 'google / SoC' Category

$10 Million Android Developer Challenge

Monday, November 12th, 2007

Google has announced their “gPhone”, and it’s a open, Linux-based software platform called Android:

And they’re celebrating by also announcing a $10 million developer challenge, two be handed out in two $5 million dollar rounds with at least 50 individual recipients each round. Pretty exciting, eh?

So does anyone have any suggestions for “i wish my phone could do this”? :) I’d love to hear your thoughts…

Django External Schema Evolution Branch

Friday, October 19th, 2007

Just an update on my former SoC2006 work…

We now no longer require a patch to Django. One import statement in allows our program to fake it via the very crafty Python language.

The new website is here:
The discussion list us here:

Plus there is an introductory video available here:

Django Schema Evolution

Thursday, July 19th, 2007

I’ve ported my schema evolution work from my SoC project last summer to Django v0.96.   To use it, download the patch below, and run the following:

$ cd /<path_to_python_dir>/site-packages/django/
$ patch -p1 < ~/<download_dir>/django_schema_evolution-v096patch.txt

It should output the following:

patching file core/
patching file db/backends/mysql/
patching file db/backends/mysql/
patching file db/backends/postgresql/
patching file db/backends/postgresql/
patching file db/backends/sqlite3/
patching file db/backends/sqlite3/
patching file db/models/fields/
patching file db/models/

To use it:

$ cd /<path_to_project_dir>/
$ ./ sqlevolve <app_name>

It should output something like this:

ALTER TABLE `main_query` CHANGE COLUMN `accuracy` `accuracynew` numeric(10, 6) NULL;
ALTER TABLE `main_query` ADD COLUMN `price` varchar(256) NULL;

Assuming you have a model such as this:

class Query(models.Model):
    query = models.CharField(maxlength=256, blank=False)
    accuracynew = models.FloatField(max_digits=10, decimal_places=6, null=True, blank=True, aka='accuracy')
    price = models.CharField(maxlength=256, null=True, blank=True) # new column

Note the aka field where I changed the name of “accuracy” to “accuracynew”.

Source code:


Let me know if you find any bugs.

UPDATE: This project is now on Google Code:

Gift from Google

Monday, June 12th, 2006

Google has sent out gifts to all SoC selectees. Here are the pictures…

the box the book the logo open

Summer of Code

Wednesday, May 24th, 2006

Google’s Summer of Code project has accepted my application. For those of you not familiar with this, basically Google funds you for a summer to work on an open source project of your choosing. It’s a fairly big w00t in the programming and academic worlds. I can’t tell you all how exciting this is. :)

The skinny: I will be implementing schema evolution for the Django project. Watch this category for further updates.

The meat of my proposal:

I would like to implement the introspection and migration schema evolution suggestions detailed here: []

I am in a unique position for this proposal because I have implemented much of this functionality before. I am the PM/tech lead for a large (~400k loc) java based web application. We have a 200+ table schema, and last December I wrote a schema manager that implements much of what is described in your schema evolution proposal. (this is no coincidence – Django’s need was my catalyst/inspiration) Obviously I would not be able to use any of the code (as it was written for an Air Force contract), but the techniques would be transferable.

The schema manager I wrote (in Java, manipulating an Oracle DB, and likely on the outer difficulty edge of any similar implementation) was developed independently from your wiki’s proposal. (it was inspired by the one-line ‘this would be hard but nice to have’ comment in the 0.9.0 documentation, IIRC) However it implements everything listed in your ‘Automatically applied migration code’ suggestion. Additionally, it supports the following:

  • automatic downgrades are supported (in addition to upgrades)
  • the application can automatically identify a schema without a ’schema version’ table
  • the application can verify the accuracy of a schema
  • multiple schema identification algorithms are simultaneously supported (for instance: primary keys, foreign keys and constraints can be named in Oracle – should a constraint name change be considered a schema version change? you decide)
  • multiple different schemas with ‘equivalent’ functionality can be mapped back to a single logical schema version (‘equivalency’ obviously being determined by the developer)

I would like to note that this would not be simply a porting project. For obvious legal reasons I would not have access to my previous code base. It would be in a different language. (I am familiar with Python, but not yet competent) It would be designed against a different database. And it would be for an object framework very different from my previous application experience. Nonetheless, many of the ‘hard’ problems associated with this type of functionality I have already solved, proven and deployed.

As far as the introspection functionality, this was prototyped, but never deployed for the following reasons:

  • my application does not have a central, unified object definition mechanism from which to base such a function
  • converting our application to such would have been prohibitive
  • other development requirements took priority

However my exploratory code towards this was promising. (you all would be proud of my tuple-based model implementation in Java – made quite the use of the new 1.5 features and had full compile-time checking of all parameters)

BTW, I briefly considered a full Java port of Django last winter. (I’ve owned for a while now) I still think it would be a good long-term idea, but a bit much for a summer project.

As far as any legal concerns you might have, I’ve contributed to open source projects before with both my company’s and the government’s knowledge and approval. (including my own project, buglist) I know the landscape well. Plus my contract will be ending soon. (on 6/30)

Anyway, I look forward to working with you all. :)
– Derek Anderson

P.S. Yes, getting *everyone* to save their migration scripts in a VCS should be an absolute, unwavering requirement. Good god it scares me how few people do this.

<>   © Copyright 2000-2005 by Derek Anderson
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