Demystifying the AWS Advanced JDBC Driver: Pools, Plugins, and the Traps I Hit Date: 2026-04-29 Status: Published TL;DR The AWS Advanced JDBC Driver wraps your database driver with a plugin chain that handles failover, read/write splitting, and connection monitoring. The critical gotcha: it can create internal connection pools separate from your application's HikariCP . If you're on v2.x with the F0 profile, you're hitting a hardcoded 30-connection ceiling regardless of your external pool config. The fix: upgrade to v3.x and use connectionPoolType=hikari with cp-MaximumPoolSize properties, or drop profiles entirely and configure plugins manually. Key invariant: cp-MaximumPoolSize >= external maximumPoolSize to avoid the internal pool becoming your bottleneck.…