Databricks 9.1 LTS is a long-term support (LTS) release of the Databricks Runtime. It features Apache Spark 3.1.2 and various improvements across machine learning, Delta Lake, and SQL capabilities.

Key enhancements in Databricks 9.1 LTS include:

Apache Spark:

• Consists of all fixes and improvements from Databricks Runtime 9.0.
• Additional bug fixes and improvements include support for ILIKE (case-insensitive LIKE).

Delta Lake:

• Improved MERGE INTO functionality for arrays of structs, resolving fields by name and evolving schemas automatically.
• Performance improvements for MERGE INTO operations with large numbers of matches.

Machine Learning (Databricks Runtime 9.1 LTS ML):

• AutoML enhancements for streamlined notebook generation.
• Improvements to the feature store include support for unsupervised learning, multiple features per FeatureLookup, custom paths for feature tables, and new PySpark data types.