The text discusses the modifications made to Delta Lake, an open-source table format originally developed by Databricks, which was integrated into a new database system referred to as Great Lakes. The original Delta Lake provides ACID transactions through multiversion concurrency control (MVCC) and is optimized for cloud-native databases performing stream processing. Modifications include replacing the standard Parquet file format with Vortex to reduce query times and memory use, transitioning from JSON to Vortex format for commit logs to save CPU time and memory, and introducing formal Vortex struct columns to eliminate the need for parsing JSON in query paths. Additionally, a centralized commit coordinator was implemented to avoid write contention, and virtual files were added to the log for atomic data compaction, allowing efficient data movement between tables without duplication risks. These enhancements have reportedly improved performance and efficiency, with aspirations to contribute these advancements back to the open-source community.