One does not simply
migrate a primary key!
PyCon Austria 2025
6.-7. April, Eisenstadt
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One does not simply migrate a primary key!
A database adventure from the Django lands.
jackie / Andrea Ida Malkah Klaura <jackie@tantemalkah.at>
https://tantemalkah.at/2025/pycon
All contents, unless otherwise noted, were produced by Andrea Ida Malkah Klauraunder a Creative Commons Attribution - Share Alike 4.0 International License.
The feminist technoscience logo on the waiting queue slide is an adaptation of a public domain image.
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What is this about?
- a story based on a true encounter
- about a (not so) simple Django application
- and its object-relational mapper (ORM)
- but mostly about relational databases and SQL
Who is we?
The base departement
at the University of Applied Arts Vienna
(a.k.a.: die Angewandte)
What do we do?
all (modern) web applications at the university (+ more)
And whoami?
- IRL: jackie
- officially: Andrea Ida Malkah Klaura
- part of the base dev team since 2020
- also a lecturer on different universities
- activist for better tech for everyone
- #morefunnotprofit
- Never Trust A Running System!
- more info on tantemalkah.at
pronouns
- in binary gender space: she/her
- in the wider gender multiverse: ze/hir
- usage: https://my.geeky.gay/pronouns/ze/hir/hirs/hirself
That gender you got at birth? That's just a tutorial gender. You're only supposed to use it to get the hang on this world's gender system and then ditch it for a stronger one, not use it your entire life, noob
And who are you?
Setting the scene
a landscape of images
or: "platform for open art education"
more details: https://imageplus.at
The dungeon map
a.k.a. the data model
The old data model
Some time before March 2024
May 2024
the actual changes
Quest outline
The demo app
https://github.com/jackie-ak/primary-key-migration-demo
Start your journey on main
Going solo
the tutorial level mode of questing (a.k.a. software engineering)
Once your app runs...
continue journey on feature/simple_solution
The path is blocked by a reverse migration troll?
Check out the vantage point on feature/solution_attempt_2
Do you want to take the path to your left?
Quest preparation
a.k.a. research
a few sparse trails
-
1st May 2022 on the Django forums:
Error when I change id to UUID
Changing the primary key in Django is problematic.
-
9th March 2023 blog post by Fabian Clemenz:
Django 101: Switching the primary key on existing models
or: living on the edge of data loss
Slaying the monster
a.k.a. proper software engineering
hopefully?
The final boss fight
takes place on feature/actual_solution
Debriefing
a.k.a. the Q & A
Outro
-
Ups, we did it again:
Commit
ac537a1(Nov 7, 2024) - And we might need to do it again
-
2024-12-17: Mahmood Nasr on medium.com:
Migrating from Integer id to UUID in Django: Hidden Pitfalls and How to Solve Them -
2025-03-20: Mohammad Gholami on medium.com:
Migrating from Integer ID to UUID in Django Without Data Loss (PostgreSQL) - 2025-03-19: a new utility for migrating int to UUID PKs pops up on GitHub: Afaneor/django-uuid-migration
Want to go on quests together?
"An RPG party on a quest, consisting of cyber mages and security witches"
- jackie@tantemalkah.at
-
other channels on tantemalkah.at
- happy to collaborate, but currently limited capacities
-
base dev team
- ... will soon be looking for an additional open source engineer / backend dev