TimescaleDB handles time-series from the last 1–90 days (hot) excellently, but at 5+ years of history the cost of PostgreSQL SSD and RAM grows faster than the business value. Apache Iceberg (a table format for the data lake) plus DuckDB (a local SQL engine) deliver a cheaper warm tier (90–730 days) and cold tier (>2 years) on S3 or MinIO. A 3-tier architecture cuts storage cost by 80–95% while keeping data queryable. This article shows how to build it for MES, where the limits are, what it costs, and how to migrate from a monolithic TimescaleDB.