Migrate data to Delta Lake

Databricks provides tools to simplify the migration of Parquet and Iceberg data into Delta Lake.

Tool	When to use
CONVERT TO DELTA SQL command	This command performs a one-time, in place conversion of Parquet and Iceberg tables into external tables.
CLONE	CLONE support for Parquet and Iceberg extends CONVERT TO DELTA functionality to include incremental support for conversion. You can use DEEP CLONE to create Unity Catalog managed tables.

Databricks recommends storing data using Unity Catalog managed tables, but in-place conversion provides many of the same benefits without needing to fully rewrite all data. Databricks recommends using CLONE if the source system continues to receive updates during the migration.