In all these cases, Query Store can help you to identify issues after the actions and to fix problems caused by changed execution plans very quickly, efficiently, and without risking business applications. A typical scenario include:

• Ensuring that Query Store is enabled and configured
• Letting Query Store work and capture information about your representative workload
• Performing the install action; this can be one of the following actions:
  • Server failover
  • Installing a SQL Server Service Pack
  • Installing a SQL Server Cumulative Update
  • Upgrading hardware configuration
  • Operating system and network patching
  • Application and service deployment
  • Letting Query Store collect information about queries and plans
  • Checking recommendations in the sys.dm_db_tuning_recommendations dynamic management view or run the Top Resources Consuming Queries report

Query Store will let you fix problems by choosing the old plan. It is a good idea to analyze why regression happened, but it is better to do this later, when you have enough time, than when problems occur on the production system.