Postgresql

PostgreSQL’s default configuration is designed to run on minimal hardware without crashing. It’s not designed to perform well. Out of the box, Postgres uses a fraction of available memory and I/O capacity. Proper tuning can improve performance by 10x or more. Memory Configuration shared_buffers The most important setting. This is Postgres’s own cache. 1 2 3 -- Default: 128MB (way too low) -- Recommended: 25% of system RAM shared_buffers = 4GB -- On a 16GB server Don’t set above 40% — the OS needs memory for its own file cache. ...

Every database connection costs something: TCP handshake, TLS negotiation, authentication, session state allocation. For PostgreSQL, that’s 1.3-2MB of memory per connection. For MySQL, 256KB-1MB. At scale, creating connections on demand kills both your database and your latency. Connection pooling solves this by reusing connections across requests. But misconfigured pools are worse than no pools — you get connection starvation, deadlocks, and debugging nightmares. Here’s how to do it right. The Problem: Connection Overhead Without pooling, a typical web request: ...

The scariest deploy isn’t code—it’s schema changes. One wrong migration can lock tables, corrupt data, or bring down production. Zero-downtime migrations require discipline, but they’re achievable. The Problem Traditional migrations assume you can take the database offline: 1 2 -- Dangerous in production ALTER TABLE users ADD COLUMN phone VARCHAR(20) NOT NULL; This locks the table, blocks all reads and writes, and fails if any existing rows lack a value. In a busy system, that’s an outage. ...