Understanding where QTA and CE Feedback are needed
The CE version that our databases use directly influences how query plans are created for queries that will be executed in those databases. And we have seen first-hand the effects of the CE every time we compared estimated number of rows with actual number of rows throughout the book – for example, in the Query plan comparison section of Chapter 9, Comparative Analysis of Query Plans, where we dealt with the Row Goal optimization scenario.
When upgrading from older versions of the SQL Database Engine to newer versions (for example, an older SQL Server version to Azure SQL Database or SQL Server 2022), we need to be conscious of how upgrading from an older CE version to a newer CE can affect our workloads – benefits are expected for the most part, but regressions can happen. For example, we discussed in Chapter 6, Discovering T-SQL Anti-Patterns in Depth, how the latest versions of the SQL Database Engine solve classic...
