PostgreSQL and the OOM Killer: Why We Use Strict Memory Overcommit
Summary
This Ubicloud blog explains why strict memory overcommit is critical for PostgreSQL to avoid catastrophic OOM kills. It describes Linux overcommit modes, how CommitLimit is calculated, and a recommended formula using 80% of total memory plus 2 GB, with attention to sidecar processes. It also recounts a kernel bug that caused phantom memory, the fleet analysis across kernels, and the Linux fix that restored proper accounting.