Rapid Battle Cards 21–30
21 — NoSQL: Document vs Key-Value vs Column vs Graph
- Document: self-contained document structure.
- Key-value: retrieve opaque/value structure by a known key.
- Column-oriented: organize sparse/large data by columns/families.
- Graph: nodes + variable connections/traversal.
- Clue: match storage/access shape to the requirement.
22 — Conceptual vs Logical Model
- CDM: high-level concepts, relationships, scope, vocabulary.
- LDM: detailed technology-independent entities, attributes, domains, keys.
- Clue: high-level business scope vs detailed requirements.
23 — Logical vs Physical Model
- LDM: technology-independent.
- PDM: DBMS/storage-specific implementation.
- Clue: vendor datatypes, indexes, partitions, physical naming → PDM.
24 — Canonical Model vs Database PDM
- Canonical: shared message/payload structure for data in motion.
- PDM: stored structure in a chosen database technology.
- Clue: interface/message vs stored database.
25 — View vs Materialized View
- View: virtual, computed/retrieved on demand.
- Materialized: instantiated/stored result refreshed at chosen times.
- Clue: on-demand vs precomputed/stored.
26 — Vertical vs Horizontal Partition
- Vertical: split columns.
- Horizontal: split rows by values/ranges.
- Clue: columns vs rows.
27 — Normalization vs Denormalization
- Normalize: remove redundancy/dependency defects and stabilize logic.
- Denormalize: intentionally add/combine redundancy in physical design for justified performance/security need.
- Clue: logical cleanup vs controlled physical redundancy.
28 — 1NF vs 2NF vs 3NF
- 1NF: atomic/no repeating groups/valid key.
- 2NF: full dependency on complete minimal key.
- 3NF: no non-key dependency on non-key.
- Clue: atomicity → full-key dependency → key-only dependency.
29 — Generalization vs Specialization
- Generalization: move common features up to supertype.
- Specialization: move distinguishing features into subtypes.
- Clue: common upward vs differences downward.
30 — Forward vs Reverse Engineering
- Forward: requirements → CDM → LDM → PDM.
- Reverse: existing DB → PDM → LDM → CDM.
- Clue: starting evidence — requirements or implementation.
Source anchors: current Battle Cards, cards 21–30.