Lakehouses and Delta Lake for ML Data

A lakehouse uses data-lake storage with table-management features. Delta Lake is an open-source table format that stores data files with a transaction log describing committed table changes. The log supports table snapshots, transactions, schema enforcement, and operations such as merge and delete. It is commonly used with Spark and also has connectors for other engines, subject to compatibility and feature support. For ML workflows, a Delta table version can identify the rows visible at a particular point in table history. A training run can record the table path and version, and experiment tracking can log the dataset input. This helps reload a historical snapshot when its files remain available. It does not automatically capture preprocessing code, random seeds, dependencies, model configuration, or external data sources; those must be recorded separately. Time travel is bounded by retention and cleanup. Delta documentation explains that VACUUM removes unreferenced data files and can make older versions unavailable; transaction-log retention is also configurable. Therefore a version number is not a permanent archival guarantee. Teams that require long-term reproducibility need retention settings, backups, or immutable exports appropriate to their policy. ACID behavior depends on storage capabilities. Delta documentation describes atomic visibility, mutual exclusion, and consistent listing assumptions and uses LogStore implementations where needed. Schema enforcement can reject incompatible writes, while schema evolution is a distinct, configurable behavior. Validate engine and protocol compatibility before relying on a feature. Delta Lake provides table consistency tools, not an end-to-end ML data governance or model reproducibility system by itself.