Should primary key always start from 1?

Question

I am migrating an old database (oracle) and there are few tables like CountryCode, DeptCode and RoleCodes, their primary key is string (Codes) and i am thinking about adding Number column as a primary key because it would work fast with joins. These tables are not really big.

I am wondering if primary key for those tables should start from number '1' or it can be started from 100 just to differentiate b/w tables PK although i don't think i would be showing them on reports.

Answer 1

For sequence-generated IDs, I would suggest starting at different values if it's easy to do (depends on your database etc). You shouldn't be using this to differentiate between them in code, but it can make testing more reasonable.

Before now, I've had a situation where I've accidentally used a foreign key one table as if it were the foreign key for another table. The tests passed as the IDs were coincidentally the same. After we discovered the problem, we changed the initial seed and found the tests were a lot clearer.