Knobit of Data modelling · K-608 · Skill

Recognises a hierarchy encoded redundantly

What it means

A recursive relationship stored as a path string or nested-set numbers. The structure is held many times over, moving one node rewrites all its descendants, and no foreign key checks the encoding. A specific form of row 3.

How it is assessed

Flags the deficient case and passes the acceptable one. Deficient: `branch.path = '/1/4/17/'` with no foreign key on the parts; moving branch 4 under another region rewrites every row below it, and a mistyped path loads Acceptable: `parent_branch_id` with a foreign key as the system of record; a path, nested set or closure table only as a derived structure with `derivation` and a DQ rule. A closure table has foreign keys on both columns

Builds on

Explains derived data and point-in-time snapshotsK-565 · Knowledge

Needed by

None