Demo: Identify and fix plan change regression in SQL Server 2017 RC1

Plan change regression happens when SQL Database changes a plan for some T-SQL query, and the new plan has the worse performance than the previous one. SQL Server 2017 has Automatic Tuning feature that enables you to easily find plan change regressions and fix them. In this post you will see the demo script that you… Read more

Monitoring automatic tuning actions using XEvents

SQL Server 2017 can automatically tune your queries by identifying and fixing SQL plan change regressions. SQL Server tracks last known good plans for each query, and if the plan for the query changes, last know good plan will be used if performance of the new plan is worse than the performance of the last… Read more

Public Preview of Compatibility Level 140 for Azure SQL Database

Today we are announcing the official public preview of compatibility level 140 in Azure SQL Database. Compatibility level 140 enables the following query optimizer changes: A trivial plan referencing Columnstore indexes will be discarded in favor of a plan that is eligible for batch mode execution. The sp_execute_external_script UDX operator is eligible for batch mode… Read more

“What are you waiting for?” – Introducing wait stats support in Query Store

Troubleshooting waits previously. Nobody likes to wait. SQL database is multithreaded system that can handle thousands of queries executed simultaneously. Since queries that are executed in parallel compete for the same resources (tables, memory, etc) they might need to wait for the resources to be available to proceed with execution. These cumulative waits can be… Read more