Determining connection costs and limits

Excessive database connections are not without risk. The level of risk we incur and what exactly qualifies as excessive are important to determine early. The company and our customers will find it extremely inconvenient if normal database activity exhausted system memory, caused timeouts due to increased context-switching, or overwhelmed the kernel with an overly large process table.

To maintain a highly available server, we must know the full impact of every single connection in terms of required memory and CPU resources. Servicing several disparate applications from various external servers is difficult, so we must provide availability while simultaneously avoiding resource exhaustion. If we properly assess the ideal balance between connection count and performance early on, we can avoid costly emergencies.

Irrespective of whether we helped specify the hardware that will host our PostgreSQL installation, it's still our job to figure out how many...