Database Connection Pooling

Opening and closing database connections for every request can significantly slow down your application. Each new connection requires TCP handshake, authentication, and memory allocation, all of which take time. Connection pooling solves this by maintaining a pool of reusable database connections.

Here's how connection pooling works. When your application starts, it creates a set of database connections and keeps them ready to use. When your code needs to query the database, it borrows a connection from the pool, uses it, and returns it back instead of closing it. This makes database operations much faster since connections are reused rather than created from scratch.

Here are some key practices to get the most out of connection pooling:

Pool Size: Start with pool size = number of CPU cores * 2. This gives enough connections to handle concurrent requests without wasting resources. Monitor connection usage and adjust if needed.

Connection Lifetime: Set a maximum lifetime for connections (usually a few hours) to prevent issues with stale connections. The pool will automatically replace old connections with fresh ones.

Timeout Settings: Set reasonable timeouts for both getting a connection from the pool and executing queries. This prevents requests from hanging when the pool is exhausted or queries are taking too long.

Monitoring: Track metrics like connection wait time, pool utilization, and connection errors. These help identify if your pool needs tuning.