Stage 8: Generate and review DDL
Knobit of Data modelling · K-827 · Skill
Recognises an event timestamp stored without a time zone
What it means
Two mirror-image defects. An event timestamp with no offset is ambiguous twice a year and incomparable across a bank that books in more than one zone. A business date — value date, booking date, maturity date, due date — stored as a timestamp invites a time component nobody means and makes date equality quietly fail.
How it is assessed
Flags the deficient case and passes the acceptable one. Deficient: `created_at TIMESTAMP` with no zone on `dim_account`, written by jobs in two regions. And `payment_value_date` as a `TIMESTAMP`, so `= DATE '2026-03-31'` matches none of the rows loaded at 23:30 Acceptable: `TIMESTAMP WITH TIME ZONE` for event times, or UTC with the convention stated in the column `comment` and nowhere else; `DATE` for `payment_value_date`, `loan_maturity_date` and `valid_from_date`/`valid_to_date`, as the sample model has them
Builds on
- Recognises a physical domain differing from the logical domainK-617 · Skill
- Explains time zones in timestamps and business datesK-854 · Knowledge
Needed by
- None