Spark connector does not support invoking Unity Catalog functions

Summary

Functions can be created and stored in Unity Catalog via the CLI (bin/uc function create), but they cannot be invoked from Spark SQL. When referencing a function in a query (e.g. catalog.schema.function_name(column)), Spark throws AnalysisException: Catalog development does not support functions.

Environment

• Unity Catalog server: 0.4.0
• Spark: 4.0.1
• Delta Lake: 4.0.1
• PostgreSQL: 17.7

Steps to Reproduce

1. Create a function via CLI:

bin/uc function create
--full_name development.sales.format_order_status
--input_params "status STRING"
--data_type STRING
--def "return 'In behandeling' if status == 'processing' else 'Verzonden' if status == 'shipped' else 'Afgeleverd' if status == 'delivered' else status"
--comment "Formats order status for display in Dutch."

2. Use the function in Spark SQL:

spark.sql("""SELECT *, development.sales.format_order_status(status) AS status_nl FROM development.sales.orders_884 LIMIT 100""")

Errors Observed

Client (Spark / PySpark)
AnalysisException: Catalog development does not support functions.

Start by reproducing the failure with the bin/uc function create command and the Spark SQL query shown in the issue. Trace how Spark resolves development.sales.format_order_status and compare that path with the Unity Catalog function created through the CLI. Done means the same SQL invocation succeeds instead of reporting that the catalog does not support functions.