Connection Pooling

Connection pooling is a performance optimization technique that maintains a cache of database connections that can be reused across multiple client requests. Creating a new database connection is expensive—it involves TCP handshake, authentication, SSL negotiation, and session setup. Connection pools maintain a set of open connections and lend them to clients as needed, dramatically reducing connection overhead. Pool configurations include minimum/maximum pool size, connection timeout, idle timeout, and connection validation. Popular connection poolers include PgBouncer (PostgreSQL), ProxySQL (MySQL), HikariCP (Java), and built-in pooling in database drivers and ORMs. Connection pooling is especially critical for serverless architectures where many short-lived functions need database access.