Recognises a lossy or unconstrained vertical split

Mida see tähendab

One entity split into two tables for width or access, where the tables do not share the key, or the one-to-one relationship between them is not enforced. Joining back produces rows that never existed, or one row gets two extensions. A dependency spanning both parts has no key to enforce it.

Kuidas seda hinnatakse

Flags the deficient case and passes the acceptable one. Deficient: `account` and `account_interest_terms`, the second with its own surrogate and joined on the product code: two accounts on one product give four rows. Or `account_interest_terms.account_id` with an FK but no unique constraint Acceptable: Both tables keyed on `account_id`; in the extension the primary key is also the foreign key, so one-to-one is enforced; whether the extension is optional is stated

Tugineb

Recognises a lossy decompositionK-514 · Oskus
Explains vertical and horizontal partitioning of tablesK-660 · Teadmine

Vajalik

Puudub