Postmortem: How a Prisma 5.9 Query and Neon 0.17 Postgres Deadlock Took Down Our User Dashboard

At 14:37 UTC on March 12, 2024, our user dashboard’s p99 latency spiked to 22 seconds, then flatlined to 0 requests per second for 47 minutes—all triggered by a single Prisma 5.9 nested write query racing against Neon 0.17’s Postgres connection poole...