// Expert guidance for distributed NoSQL databases (Cassandra, DynamoDB). Focuses on mental models, query-first modeling, single-table design, and avoiding hot partitions in high-scale systems.
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| version | 4.1.0-fractal |
| name | nosql-expert |
| description | Expert guidance for distributed NoSQL databases (Cassandra, DynamoDB). Focuses on mental models, query-first modeling, single-table design, and avoiding hot partitions in high-scale systems. |
This skill provides professional mental models and design patterns for distributed wide-column and key-value stores (specifically Apache Cassandra and Amazon DynamoDB).
Unlike SQL (where you model data entities), or document stores (like MongoDB), these distributed systems require you to model your queries first.
| Feature | SQL (Relational) | Distributed NoSQL (Cassandra/DynamoDB) |
|---|---|---|
| Data modeling | Model Entities + Relationships | Model Queries (Access Patterns) |
| Joins | CPU-intensive, at read time | Pre-computed (Denormalized) at write time |
| Storage cost | Expensive (minimize duplication) | Cheap (duplicate data for read speed) |
| Consistency | ACID (Strong) | BASE (Eventual) / Tunable |
| Scalability | Vertical (Bigger machine) | Horizontal (More nodes/shards) |
The Golden Rule: In SQL, you design the data model to answer any query. In NoSQL, you design the data model to answer specific queries efficiently.