Microsoft SQL Server 2008 R2 Unleashed- P138: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 SQL Server 2008 is not as much of a quantum leap forward from SQL Server 2005 | 1314 CHAPTER 36 Query Analysis Stream Aggregate a i You most often see the Stream Aggregate operation when you are aggregating a single input such as a DISTINCT clause or a SUM COUNT MAX MIN or AVG operator. The output of this operator may be referenced by later operators in the query returned to the client or both. Because the Stream Aggregate operator requires input ordered by the columns within its groups a Sort operator often precedes the Stream Aggregate operator unless the data is already sorted due to a prior Sort operator or due to an ordered index seek or scan. Table Delete Table Insert Table Scan and Table Update You see the Table Delete Table Insert Table Scan and Table Update operators when the indicated operation is being performed against that table as a whole. The presence of these operators does not always mean a problem exists although a table scan can be an indicator that you might need some indexes to support the query. A table scan may be performed on small tables even if appropriate indexes exist especially when the table is only a single page or two in size. Table-valued Function L-E The Table-valued Function operator is displayed for queries with calls to table-valued functions. The Table-valued Function operator evaluates the table-valued function and the resulting rows are stored in the tempdb database. When the parent operators request the rows the Table-valued Function operator returns the rows from tempdb. Top I The Top operator indicates a limit that is set either by number of rows or a percentage on the number of results to be returned from the input. The ToolTip may also contain a list of the columns being checked for ties if the WITH TIES option has been specified. Parallelism Operators The Parallelism operators indicate that parallel query processing is being performed. The associated logical operator displayed is one of the Distribute Streams Gather Streams or Repartition Streams logical operators. Distribute Streams The Distribute
