Module 5
Database Design
Master database fundamentals: SQL vs NoSQL tradeoffs, sharding strategies, replication patterns, and consistency models.
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SQL vs NoSQL Architecture
Choose the right database type based on your data and query patterns.
Choosing the right database type is crucial for system design.
SQL (Relational) Databases
Examples: PostgreSQL, MySQL, Oracle
Strengths:
•ACID transactions (Atomicity, Consistency, Isolation, Durability)
•Strong schema enforcement
•Complex queries with JOINs
•Mature tooling and ecosystem
Best For:
•Financial systems
•Complex relationships
•When data integrity is critical
•Structured, well-defined data
NoSQL Databases
Document Stores (MongoDB, CouchDB)
•Flexible schema, JSON-like documents
•Good for content management, catalogs
Key-Value Stores (Redis, DynamoDB)
•Simple get/set operations
•Extremely fast, good for caching
Column-Family (Cassandra, HBase)
•Wide columns, time-series data
•High write throughput
Graph Databases (Neo4j, Amazon Neptune)
•Relationship-focused queries
•Social networks, recommendations
Decision Framework:
•Need transactions? → SQL
•Flexible schema? → Document store
•Simple lookups at scale? → Key-value
•Time-series or analytics? → Column-family
•Complex relationships? → Graph