DynamoDB + ElectroDB

DynamoDB Single-Table Design

Single-table design stores all entity types in one DynamoDB table. Entities are distinguished by PK/SK prefix patterns.

Core principles

• Design for access patterns, not entities: Start from how data will be queried, then design keys around those patterns. Unlike relational databases, you cannot add arbitrary queries after the fact.
• Use composite keys: PK and SK are strings composed of multiple attributes (e.g., USER#<userId> for PK, PROFILE for SK). ElectroDB handles this composition automatically.
• GSIs extend access patterns: A Global Secondary Index (GSI) provides an alternative PK/SK combination for queries that the main table's keys don't support.
• Denormalize intentionally: Store data redundantly across items when read patterns demand it. Write-time aggregation (updating a counter when an item is created) avoids expensive read-time scans.
• Avoid scans: Full table scans are expensive and slow. Every data access should use a Query (PK + optional SK condition) or GetItem (exact PK + SK).

Key design patterns