6. etapp: Füüsilise andmemudeli kujundamine
Kompetentsi Andmete modelleerimine knobit · K-608 · Oskus
Recognises a hierarchy encoded redundantly
Mida see tähendab
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.
Kuidas seda hinnatakse
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
Tugineb
- Explains derived data and point-in-time snapshotsK-565 · Teadmine
Vajalik
- Puudub