War Story: We Ditched MySQL 8.0 for Neon 0.18 Postgres and Cut Query Latency by 20%

After 14 months of fighting MySQL 8.0’s write amplification, unpredictable p99 latency spikes that peaked at 420ms during Black Friday sales, and $4.2k/month in idle replica costs for analytical queries, we migrated our 12TB production e-commerce wor...