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Microsoft SQL Server 2008 R2 Unleashed- P137

Microsoft SQL Server 2008 R2 Unleashed- P137:SQL Server 2005 provided a number of significant new features and enhancements over what was available in SQL Server 2000. This is not too surprising considering there was a five-year gap between these major releases.Microsoft SQL Server 2008 is not as much of a quantum leap forward from SQL Server 2005 | 1304 CHAPTER 36 Query Analysis Execution Plan ToolTips When a graphical execution plan is presented in the Query Analyzer you can get more information about each node in the execution plan by moving the mouse cursor over one of the icons. ToolTips for estimated execution plans are slightly different from the ToolTips displayed for an execution plan that is generated when a query is actually executed. The ToolTip displayed for an estimated execution plan provides the following information Physical Operation Lists the physical operation being performed for the node such as a Clustered Index Scan Index Seek Aggregate Hash or Nested Loop Join and so on. Logical Operation Lists the logical operation that corresponds with the physical operation such as the logical operation of a union being physically performed as a merge join. The logical operator if different from the physical operator is listed in parentheses below the physical operator in the icon text in the graphical execution plan. Essentially the logical operators describe the relational operation used to process a statement while the physical operation describes how it is being performed. Estimated I O Cost Indicates the estimated relative I O cost for the operation. Preferably this value should be as low as possible. Estimated CPU Cost Lists the estimated relative CPU cost for the operation. Estimated Number of Executions Lists the estimated number of times this operation will be executed. Estimated Operator Cost Indicates the estimated cost to execute the physical operation. For best performance you want this value as low as possible. Estimated Number of Rows Lists the estimated number of rows to be output by the operation and passed on to the parent operation. Estimated Row Size Indicates the estimated average row size of the rows being passed through the operator. Estimated Subtree Cost Lists the estimated cumulative total cost of this operation and all child operations preceding it in the same subtree. .