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SQL Server 2008 R2
Many administrators address performance problems solely by tuning system-level server performance: for example, memory size, type of file system, number and type of processors, and so on. However, many performance problems cannot be resolved this way. They are better addressed by also analyzing the application queries and updates that the application submits to the database, and how these queries and updates interact with the data contained in the database and the database schema.
Contains information about the SQL Server 2005 "missing indexes" feature. When the query optimizer analyzes a query to determine the best execution plan, it automatically generates information about indexes that would improve query performance even if the indexes do not exist. The missing indexes feature enables you to retrieve this information about missing indexes.