Sandra from InitAg (previously) works with Bjørn, and Bjørn has some ideas about how database schemas should be organized.
First, users should never see an auto-incrementing ID. That means you need to use UUIDs. But UUIDs are large and expensive, so they should never be your primary key, use an auto-incrementing ID for that.
This is not, in and of itself, a radical or ridiculous statement. I've worked on many a database that followed similar rules. I've also seen "just use a UUID all the time" become increasingly common, especially on distributed databases, where incrementing counters is expensive.
One can have opinions and disagreements about how we handle IDs in a database, but I wouldn't call anything a WTF there.
No, the WTF is how Bjørn would design his cross-reference tables. You know, the tables which exist to permit many-to-many relationships between two other tables? Tables that should just be tableA.id and tableB.id?
Table "public.foo_bar"
Column | Type | Collation | Nullable | Default
-----------+------------------------+-----------+----------+------------------------------------
id | integer | | not null | nextval('foo_bar_id_seq'::regclass)
foo_id | integer | | not null |
bar_id | integer | | not null |
uuid | character varying(128) | | not null |
Yes, every row in this table has an ID, which isn't itself a terrible choice, and a UUID, despite the fact that the ID of these rows should never end up in output anyway. It exists only to facilitate queries, not store any actual data.
I guess, what's the point of having a rule if you don't follow it unthinkingly at all times?
This post originally appeared on The Daily WTF.