Pattern 30 / SCALE

Database Connection Pooling

Use this when avoiding expensive database connection setup per request.

Pressure: Avoiding expensive database connection setup per request
Mechanism: Keep a bounded pool of reusable connections and let requests borrow/return them
Toll: Too few connections queue requests; too many overload the database

Diagram for Database Connection Pooling — Architecture plate30

Executive brief

Database Connection Pooling fits when avoiding expensive database connection setup per request. Mechanism: keep a bounded pool of reusable connections and let requests borrow/return them. Use it for web apps and APIs that talk to relational databases. The toll: too few connections queue requests; too many overload the database.

Use when

Web apps and apis that talk to relational databases.

Example

Rails/puma workers sharing a controlled postgresql pool.

Review framing

Describe the pressure first, then the mechanism, then the cost. That keeps the design grounded.

Same pressure family

Scaling Patterns

26Horizontal Scaling 27Vertical Scaling 28Load Balancing 29Auto-Scaling