Microsoft SQL Server 2008 R2 Unleashed- P122

Microsoft SQL Server 2008 R2 Unleashed- P122: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 | 1154 CHAPTER 34 Data Structures Indexes and Performance LISTING DBCC SHOW_STATISTICS Output for the aunmind Index on the authors Table dbcc show_statistics authors aunmind go Name Updated Rows Rows Sampled Steps Density Average key length String Index Filter Expression Unfiltered Rows aunmind Mar 14 2010 10 20PM 172 172 148 1 YES NULL 172 1 row s affected All density Average Length Columns au_lname au_lname au_fname au_lname au_fname au_id 3 row s affected RANGE_HI_KEY RANGE_ROWS EQ_ROWS DISTINCT_RANGE_ROWS AVG_RANGE_ROWS Ahlberg 0 2 0 1 Alexander 0 1 0 1 Amis 0 1 0 1 Arendt 0 1 0 1 Arnosky 0 1 0 1 Bate 0 1 0 1 Bauer 0 1 0 1 Benchley 0 1 0 1 Bennet 0 1 0 1 Blotchet-Halls 0 1 0 1 . del Castillo 0 1 0 1 Dillard 0 1 0 1 Doctorow 0 1 0 1 Doyle 0 1 0 1 Durrenmatt 2 1 2 1 Eastman 0 1 0 1 . Gringlesby 0 1 0 1 Grisham 0 1 0 1 Gunning 0 1 0 1 Download from Index Statistics 1155 Hill 0 1 0 1 Hutchins 3 2 3 1 Ionesco 0 1 0 1 Ishiguro 0 1 0 1 III Tyler 0 1 0 1 Van Allsburg 0 1 0 1 Van der 0 1 0 1 Van der Meer 0 1 0 1 von Goethe 0 1 0 1 Walker 0 1 0 1 Warner 0 1 0 1 White 0 2 0 1 Wilder 0 1 0 1 Williams 0 2 0 1 Wilson 0 1 0 1 Yates 0 1 0 1 Yokomoto 0 1 0 1 Young 0 1 0 1 34 Looking at the output you can determine that the statistics were last updated on March 14 2010. At the time the statistics were generated the table had 172 rows and all 172 rows were sampled to generate the statistics no filtering was applied . The average key length is bytes. From the All density information you can see that this index is highly selective. A low density means high selectivity index densities are covered shortly. After the general information and the index densities the index histogram is displayed. The Statistics Histogram Up to 200 sample values can be stored in the statistics histogram. Each sample value is called a step. The sample value stored in each step is the endpoint of a range of .