Merge pull request #12853 from dbrownems/patch-1

Clarifying that unused unique indexes will not be dropped

Author: ktoliver

articles/sql-database/sql-database-automatic-tuning.md

@@ -59,7 +59,7 @@ For an overview of how automatic tuning works and for typical usage scenarios, s
 
 Automatic tuning options available in Azure SQL Database are:
  1. **CREATE INDEX** - identifies indexes that may improve performance of your workload, creates indexes, and automatically verifies that performance of queries has improved.
- 2. **DROP INDEX** - identifies redundant and duplicate indexes daily, and indexes that were not used for a long time (>90 days). Note that this option is not compatible with applications using partition switching and index hints.
+ 2. **DROP INDEX** - identifies redundant and duplicate indexes daily, except for unique indexes, and indexes that were not used for a long time (>90 days). Note that this option is not compatible with applications using partition switching and index hints.
  3. **FORCE LAST GOOD PLAN** - identifies SQL queries using execution plan that is slower than the previous good plan, and queries using the last known good plan instead of the regressed plan.
 
 Automatic tuning identifies **CREATE INDEX**, **DROP INDEX**, and **FORCE LAST GOOD PLAN** recommendations that can optimize your database performance and shows them in [Azure portal](sql-database-advisor-portal.md), and exposes them through [T-SQL](https://docs.microsoft.com/sql/t-sql/statements/alter-database-transact-sql-set-options?view=azuresqldb-current) and [REST API](https://docs.microsoft.com/rest/api/sql/serverautomatictuning).