UNIQUE constraint support is now in Public Preview

Databricks SQL now supports informational UNIQUE constraints on Unity Catalog Delta Lake tables. Foreign keys can reference UNIQUE columns, and RELY on a UNIQUE constraint enables join elimination and DISTINCT simplification on Photon enabled compute. Applies to: Databricks SQL Databricks Runtime Adds an informational primary key, an informational foreign key, or an informational unique constraint as part of a CREATE TABLE or CREATE MATERIALIZED VIEW statement.