Lakehouse Tables

A folder of Parquet 129 files is not a table: concurrent writers interleave, readers see half-written folders, and a rename silently empties a column (Compatibility Modes Compared). Open table formats (Apache Iceberg 129 , Delta Lake 237,929 , Apache Hudi 129 ) keep the Parquet files and add metadata listing which files form each snapshot, bringing atomic commits, time travel and row-level deletes. For evolution they add the field ID: Iceberg gives each column a permanent ID, stored in every Parquet file's schema as PARQUET:field_id, and resolves columns by ID, so a rename is a metadata change and a reused name never revives old values. Delta Lake's column mapping does the same. Lakehouses, Data Quality and Governance builds BookNest's history as Iceberg tables; Safe Schema Evolution Rules gives the evolution rules.