07. NoSQL theory - revision mindmap
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The map is a completed revision summary. Cover a branch and reconstruct it, then try the linked chapter practice. Read the image at full size when labels are small.
Text version
Start with the requirement
- Shape of records and changing attributes
- Relationships and reporting needs
- Read/write patterns and volume
- Integrity, consistency and availability needs
Relational strengths
- Tables and explicit schema
- Keys and relationships
- Joins for varied reports
- Transaction support for related updates
NoSQL models
- Key–value: key lookup
- Document: fields, nested objects and arrays
- Wide-column: appropriate distributed keyed workloads
- Graph: nodes, edges and relationship traversal
Address a design difficulty
- Varied product attributes → flexible documents
- Read nested details together → embedding
- Large workload → suitable partitioning
- Failure tolerance → suitably configured replication
Tradeoffs and vocabulary
- Vertical: strengthen a machine; horizontal: add machines
- Flexible schema still needs validation
- Repeated embedded facts complicate updates
- Product-dependent transactions, querying and scaling
Worked example & exam traps
- Book document: title + author. Shoe document: size + colour.
- Different fields fit varied catalogue items; validate required fields.
- Embedding can simplify reads; duplicated facts still need consistent updates.
- Avoid: NoSQL has no structure/transactions; always faster; SQL cannot scale
Sources and reading
This map condenses Chapter 07 and its source trail. Use the self-learning reading guide for the corresponding VJC pages and A notes. It does not add topics to the stated promo scope.