Support for more delta/parquet data types

[c_mettler]

The nested types array, map, and struct, along with the unnest function, are widely used by other vendors. Adding T-SQL support to the SQL Server/Warehouse family would greatly improve and enable interoperability between third-party delta/parquet-based systems.

mupawar on ‎09-17-2025 06:24 PM 

Currently complext type (json, struct) are supported in Onelake endpoint but not in SQL endpoint which prevents these important payload data types to be explored or used in Power BI. In big data world such fields are very common as many data generated through IoT are partially parsed in individual columns and raw json payload is left for future use or as on need basis.

Before parquet - we use to store them as MapType which make them easy to further use. Adding this feature will do both - parsing those field easy for end user and also migration of existing data possible.

[udaykumarreddy_]

Lakehouse SQL Endpoint support for nested types array, map, and struct is an essential feature

[BHouston1]

Appears to be unsupported currently for both Lakehouse and Warehouse