Better docs to abandon prejudice

[guettli]

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A thread[1] on django-devel showed, that there are fears of single table inheritance.

• There is one table which holds all data.
• STI reduces the database to key-value store
• All values are nullable

AFAIK there are two tables for this:

class Animal(TypedModel):
    pass
class Canine(Animal):
    pass

class Fruit(TypedModel):
    pass
class Aple(Fruit):
   pass

It is very easy to make one column not nullable: Add a constraint which checks the type column and the column which should be not nullable. It could be implemented in django typed models to implemented this:

Pseudocode for constraint:

if type=="Aple":
    check color is not NULL

Thread on django-devel https://groups.google.com/d/msg/django-developers/-UOM8HNUnxg/keyHsbGE6WgJ

[craigds]

Sure thing. I'm pretty rubbish at writing docs unfortunately.

I replied to the thread. Will wait a bit to see if Russell KM replies, since I don't understand his key-value-store objection at all. Maybe he'll shed some light on his understanding of STI

[guettli]

Yes, the problem here is not technology. It is human fear. You don't need to care about 1M NULL values in columns. Modern databases handle this very well.

Related: Jacob Kaplan-Moss "Django gotcha: concrete inheritance" http://jacobian.org/writing/concrete-inheritance/