Delta Lake and Iceberg are great for managing offline, big data workloads like batch analytics and ETL on data lakes. They're not built for real-time queries or high-throughput writes.

GreptimeDB, on the other hand, is optimized for real-time, time-series data like IoT and observability metrics, but it's not suited for offline batch processing.

Choose Delta Lake or Iceberg for offline analytics at scale. Use GreptimeDB for fast, real-time data ingestion and queries. Together, they can complement each other: GreptimeDB handles real-time data, while Delta Lake/Iceberg manages offline analytics.