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
Schemas and Databases in an Agile World
Search
Andrew Godwin
April 24, 2014
Programming
4
260
Schemas and Databases in an Agile World
A talk I gave at CRAFT 2014 in Budapest
Andrew Godwin
April 24, 2014
Tweet
Share
More Decks by Andrew Godwin
See All by Andrew Godwin
Reconciling Everything
andrewgodwin
1
330
Django Through The Years
andrewgodwin
0
220
Writing Maintainable Software At Scale
andrewgodwin
0
450
A Newcomer's Guide To Airflow's Architecture
andrewgodwin
0
360
Async, Python, and the Future
andrewgodwin
2
680
How To Break Django: With Async
andrewgodwin
1
730
Taking Django's ORM Async
andrewgodwin
0
730
The Long Road To Asynchrony
andrewgodwin
0
660
The Scientist & The Engineer
andrewgodwin
1
780
Other Decks in Programming
See All in Programming
Improving my own Ruby thereafter
sisshiki1969
1
160
Introducing ReActionView: A new ActionView-compatible ERB Engine @ Rails World 2025, Amsterdam
marcoroth
0
710
rage against annotate_predecessor
junk0612
0
170
Navigating Dependency Injection with Metro
zacsweers
3
2.5k
HTMLの品質ってなんだっけ? “HTMLクライテリア”の設計と実践
unachang113
4
2.9k
複雑なフォームに立ち向かう Next.js の技術選定
macchiitaka
2
210
Laravel Boost 超入門
fire_arlo
3
220
Cache Me If You Can
ryunen344
2
3k
MCPとデザインシステムに立脚したデザインと実装の融合
yukukotani
4
1.5k
個人軟體時代
ethanhuang13
0
330
奥深くて厄介な「改行」と仲良くなる20分
oguemon
1
560
FindyにおけるTakumi活用と脆弱性管理のこれから
rvirus0817
0
530
Featured
See All Featured
Creating an realtime collaboration tool: Agile Flush - .NET Oxford
marcduiker
31
2.2k
Intergalactic Javascript Robots from Outer Space
tanoku
272
27k
Understanding Cognitive Biases in Performance Measurement
bluesmoon
29
1.9k
Designing Experiences People Love
moore
142
24k
The Language of Interfaces
destraynor
161
25k
ピンチをチャンスに:未来をつくるプロダクトロードマップ #pmconf2020
aki_iinuma
127
53k
RailsConf 2023
tenderlove
30
1.2k
Stop Working from a Prison Cell
hatefulcrawdad
271
21k
4 Signs Your Business is Dying
shpigford
184
22k
What's in a price? How to price your products and services
michaelherold
246
12k
Side Projects
sachag
455
43k
For a Future-Friendly Web
brad_frost
180
9.9k
Transcript
Andrew Godwin @andrewgodwin DATABASES SCHEMAS in an agile world &
Andrew Godwin Core Developer Senior Engineer
Schemas Explicit & Implicit
Explicit Schema ID int Name text Weight uint 1 2
3 Alice Bob Charles 76 84 65 Implicit Schema { "id": 342, "name": "David", "weight": 44, }
Silent Failure { "id": 342, "name": "David", "weight": 74, }
{ "id": 342, "name": "Ellie", "weight": "85kg", } { "id": 342, "nom": "Frankie", "weight": 77, } { "id": 342, "name": "Frankie", "weight": -67, }
Schemas inform Storage
PostgreSQL
Adding NULLable columns: instant But must be at end of
table
CREATE INDEX CONCURRENTLY Slower, and only one at a time
Constraints after column addition This is more general advice
MySQL Locks whole table Rewrites entire storage No DDL transactions
Oracle / MSSQL / etc. Look into their strengths
Workflows Databases aren't code...
You can't put your database in a VCS You can
put your schema in a VCS But your data won't always survive.
Django Migrations Codified schema change format
None
Migrations aren't enough You can't automate away a social problem!
What if we got rid of the schema? That pesky,
pesky schema.
The Nesting Problem { "id": 123, "name": "Andrew", "friends": [
{"id": 456, "name": "David"}, {"id": 789, "name": "Mazz"}, ], "likes": [ {"id": 22, "liker": {"id": 789, "name", "Mazz"}}, ], }
You don't have to use a document DB (like CouchDB,
MongoDB, etc.)
Schemaless Columns ID int Name text Weight uint Data json
1 Alice 76 { "nickname": "Al", "bgcolor": "#ff0033" }
But that must be slower... Right?
Comparison (never trust benchmarks) Loading 1.2 million records PostgreSQL MongoDB
76 sec 8 min Sequential scan PostgreSQL MongoDB 980 ms 980 ms Index scan (Postgres GINhash) PostgreSQL MongoDB 0.7 ms 1 ms
Reasonable queries SELECT id, title FROM articles WHERE attributes->'author'->>'first_name' =
'cory'
A hybrid solution Normal columns for more static data (e.g.
id, title) Schemaless blobs for variable data (e.g. styling)
Lessons
Schemas are your friend Explicit definitions or checks will save
you
Read only mode It makes DB downtime more palatable
Work to your DBs strengths It's not just a dumb
data store
Coordinate your team A little coorindation pays big dividends
Try hybrid schemas Particularly good for CMSs or enterprise software
Thanks! Andrew Godwin @andrewgodwin eventbrite.com/jobs are hiring: