Database Design

Good database design ensures data integrity, performance, and scalability.

Design principles

• Normalization: Eliminate redundancy, reduce anomalies.
• Denormalization: Strategic redundancy for performance.
• Consistency: ACID properties (Atomicity, Consistency, Isolation, Durability).
• Scalability: Plan for growth and distribution.

Key concepts

• Primary key: Unique identifier for each record.
• Foreign key: References primary key in another table.
• Indexes: Speed up queries on frequently searched columns.
• Constraints: Rules enforcing data integrity.
• Relationships: One-to-one, one-to-many, many-to-many.

Database types

• Relational (SQL): PostgreSQL, MySQL, SQL Server.
• Document: MongoDB, CouchDB.
• Key-value: Redis, DynamoDB.
• Graph: Neo4j, ArangoDB.
• Time-series: InfluxDB, TimescaleDB.

Common patterns

• UUID primary keys: Globally unique, distributed-friendly.
• Soft deletes: Mark as deleted vs hard deletion.
• Audit columns: created_at, updated_at, created_by.
• Partitioning: Split large tables by date/region.
• Sharding: Horizontal distribution across servers.

Design process

1. Define requirements and entities.
2. Identify relationships between entities.
3. Normalize to 3rd normal form (3NF).
4. Add indexes for common queries.
5. Optimize based on performance testing.
6. Plan for backup and recovery.