Upgrade to Pro
— share decks privately, control downloads, hide ads and more …
Speaker Deck
Features
Speaker Deck
PRO
Sign in
Sign up for free
Search
Search
Database Migrations, South, And You
Search
Andrew Godwin
September 08, 2009
Programming
0
170
Database Migrations, South, And You
A talk I gave at DjangoCon US 2009
Andrew Godwin
September 08, 2009
Tweet
Share
More Decks by Andrew Godwin
See All by Andrew Godwin
Reconciling Everything
andrewgodwin
1
310
Django Through The Years
andrewgodwin
0
200
Writing Maintainable Software At Scale
andrewgodwin
0
440
A Newcomer's Guide To Airflow's Architecture
andrewgodwin
0
350
Async, Python, and the Future
andrewgodwin
2
660
How To Break Django: With Async
andrewgodwin
1
720
Taking Django's ORM Async
andrewgodwin
0
720
The Long Road To Asynchrony
andrewgodwin
0
650
The Scientist & The Engineer
andrewgodwin
1
760
Other Decks in Programming
See All in Programming
PHP 8.4の新機能「プロパティフック」から学ぶオブジェクト指向設計とリスコフの置換原則
kentaroutakeda
2
670
High-Level Programming Languages in AI Era -Human Thought and Mind-
hayat01sh1da
PRO
0
620
Select API from Kotlin Coroutine
jmatsu
1
190
Modern Angular with Signals and Signal Store:New Rules for Your Architecture @enterJS Advanced Angular Day 2025
manfredsteyer
PRO
0
150
GitHub Copilot and GitHub Codespaces Hands-on
ymd65536
1
130
5つのアンチパターンから学ぶLT設計
narihara
1
130
Code as Context 〜 1にコードで 2にリンタ 34がなくて 5にルール? 〜
yodakeisuke
0
110
What Spring Developers Should Know About Jakarta EE
ivargrimstad
0
330
GraphRAGの仕組みまるわかり
tosuri13
8
500
Create a website using Spatial Web
akkeylab
0
310
WindowInsetsだってテストしたい
ryunen344
1
200
今ならAmazon ECSのサービス間通信をどう選ぶか / Selection of ECS Interservice Communication 2025
tkikuc
20
3.7k
Featured
See All Featured
GitHub's CSS Performance
jonrohan
1031
460k
Git: the NoSQL Database
bkeepers
PRO
430
65k
Side Projects
sachag
455
42k
Building Flexible Design Systems
yeseniaperezcruz
328
39k
What's in a price? How to price your products and services
michaelherold
246
12k
Large-scale JavaScript Application Architecture
addyosmani
512
110k
The Illustrated Children's Guide to Kubernetes
chrisshort
48
50k
Agile that works and the tools we love
rasmusluckow
329
21k
Writing Fast Ruby
sferik
628
62k
StorybookのUI Testing Handbookを読んだ
zakiyama
30
5.8k
Creating an realtime collaboration tool: Agile Flush - .NET Oxford
marcduiker
30
2.1k
The Art of Delivering Value - GDevCon NA Keynote
reverentgeek
15
1.5k
Transcript
database�migrations, southand�you Andrew�Godwin
[email protected]
What�are�migrations? http://www.flickr.com/photos/moonjazz/1216783552/
They're�NOT�moving�data�from� one�database�to�another. http://www.flickr.com/photos/shindotv/3835365427/
Better�name:�Schema�Evolution. http://www.flickr.com/photos/fmc550uz/3562899067/
Django�has�nothing�built-in.
+ + =
+ + = Migration�1:�Creates�table�A Migration�2:�Creates�table�B Migration�3:�Adds�field�to�A, ������������������������creates�t able�C Apply�each�in�order,�get�current�schema
One�set�of�migrations�per�app. http://www.flickr.com/photos/dan_h/2517103627/
Apps�aren't�really�independent. http://www.flickr.com/photos/johnbullas/3301805150/
None
None
Is�your�app�fresh,�or�old? http://www.flickr.com/photos/matthewfch/536763437/
Fresh? -�Populate�appname/models.py -�Make�your�initial�migration: ./manage.py startmigration appname --initial -�Apply�that�migration ./manage.py migrate
appname
Already�syncdb'd? -�Locally,�run: ./manage.py convert_to_south appname -�Commit,�and�then�on�others�do: ./manage.py migrate --fake appname
0001 (see:�south.aeracode.org/wiki/ConvertingAnApp)
Migrations�are�flexible. http://www.flickr.com/photos/dunechaser/2630434670/
Autodetection ./manage.py startmigration \ --auto appname added_some_column Use�the�autodetector Name�of�the�app Suffix�of�the�new�migration
class Migration: def forwards(self, orm): # Adding field 'Adopter.lizard2' db.add_column('southdemo_adopter',
'lizard2', orm['southdemo.adopter:lizard2']) def backwards(self, orm): # Deleting field 'Adopter.lizard2' db.delete_column('southdemo_adopter', 'lizard2_id')
We�'freeze'�model�definitions. http://www.flickr.com/photos/stuckincustoms/3410783929/
models = { 'southdemo.adopter' : { 'first_name': ( 'django.db.models.fields.CharField' ,
[], {'max_length': '50'} ), 'lizard': ( 'django.db.models.fields.related.ForeignKey' , [], { 'related_name' : "'adopters'", 'to': "orm['southdemo.Lizard']" } ), ... }
We�migrate�data,�too. http://www.flickr.com/photos/ian-s/2152798588/
def forwards(self, orm): for adopter in orm.Adopter.objects.all(): try: adopter.first_name, adopter.last_name
= \ adopter.name.split( " ", 1) except ValueError : adopter.first_name, adopter.last_name = \ adopter.name, "" adopter.save()
Roll�your�own�migrations. http://www.flickr.com/photos/thomashawk/93819794/
Unit�test�integration,�if�you�want http://www.flickr.com/photos/cobalt/409924867/
The�Future�World�Of�Tomorrow http://www.flickr.com/photos/stuckincustoms/211566219/
Thanks�for�listening. http://www.flickr.com/photos/sovietuk/378834721/ http://south.aeracode.org Andrew�Godwin
[email protected]
Thanks�for�listening. http://www.flickr.com/photos/sovietuk/378834721/ http://south.aeracode.org Andrew�Godwin
[email protected]
@andrewgodwin