Performance Tuning with SQL Server Dynamic Management Views

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Chapter 5: Indexing Strategy and Maintenance This DMF offers many more columns; for example, to investigate use of row overflow data, LOB data, and so on. For a full listing, see Books Online. Let's take a look at this DMF in action. Detailed activity information for indexes not used for user reads The script in Listing 5.8 isolates just those indexes that are not being used for user reads, courtesy of sys.dm_db_index_usage_stats, and then provides detailed information on the type of writes still being incurred, using the leaf_*_count and nonleaf_*_ count columns of sys.dm_db_index_operational_stats. In this way, you gain a deep feel for how indexes are being used, and just exactly how much the index is costing you. SELECT '[' + DB_NAME() + '].[' + su.[name] + '].[' + o.[name] + ']' AS [statement] , i.[name] AS [index_name] , ddius.[user_seeks] + ddius.[user_scans] + ddius.[user_lookups] AS [user_reads] , ddius.[user_updates] AS [user_writes] , ddios.[leaf_insert_count] , ddios.[leaf_delete_count] , ddios.[leaf_update_count] , ddios.[nonleaf_insert_count] , ddios.[nonleaf_delete_count] , ddios.[nonleaf_update_count] FROM sys.dm_db_index_usage_stats ddius INNER JOIN sys.indexes i ON ddius.[object_id] = i.[object_id] AND i.[index_id] = ddius.[index_id] INNER JOIN sys.partitions SP ON ddius.[object_id] = SP.[object_id] AND SP.[index_id] = ddius.[index_id] INNER JOIN sys.objects o ON ddius.[object_id] = o.[object_id] INNER JOIN sys.sysusers su ON o.[schema_id] = su.[UID] INNER JOIN sys.[dm_db_index_operational_stats](DB_ID(), NULL, NULL, NULL) AS ddios ON ddius.[index_id] = ddios.[index_id] 192
Chapter 5: Indexing Strategy and Maintenance AND ddius.[object_id] = ddios.[object_id] AND SP.[partition_number] = ddios.[partition_number] AND ddius.[database_id] = ddios.[database_id] WHERE OBJECTPROPERTY(ddius.[object_id], 'IsUserTable') = 1 AND ddius.[index_id] > 0 AND ddius.[user_seeks] + ddius.[user_scans] + ddius.[user_lookups] = 0 ORDER BY ddius.[user_updates] DESC , su.[name] , o.[name] , i.[name ] Listing 5.8: Detailed write information for unused indexes. Upon review of the output it's quite clear that some of these indexes are still being hammered by inserts even though the users are not benefiting from their existence in regard to reads. If I encountered metadata like this in the real world (wink, wink) you could be sure that I would do something about it. 193
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High Performance SQL Server Perform
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Copyright Louis Davidson and Tim Fo
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Dissecting user activity ..........
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Getting Stats about tempdb Usage ..
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Server (PASS) since 2002. He has al
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Tim Ford I dedicate this book to Am
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13 Introduction on those objects th
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Code Examples 15 Introduction Throu
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Chapter 1: Using Dynamic Management
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DMO Security and Permissions Chapte
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We can find out, for example: Chapt
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Beware of the watcher effect Chapte
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Chapter 2: Connections, Sessions an
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Sysprocesses versus DMOs Chapter 2:
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Listing 2.3: Who is connected? Chap
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Listing 2.4: Who is executing what
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Logins with more than one session C
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DECLARE @days_old SMALLINT SELECT @
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• dbcc shrinkdatabase / shrinkfil
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This will return (with a different
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Who is running what, right now? Cha
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Summary Chapter 2: Connections, Ses
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73 Chapter 3: Query Plan Metadata P
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75 Chapter 3: Query Plan Metadata P
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77 Chapter 3: Query Plan Metadata t
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79 Chapter 3: Query Plan Metadata U
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SELECT TOP 10 object_id , name FROM
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Dissecting the SQL text 83 Chapter
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Figure 3.2: Three queries returned
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87 Chapter 3: Query Plan Metadata T
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89 Chapter 3: Query Plan Metadata
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Criteria in determing plan reuse 91
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For a server that had been up for t
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Listing 3.9: Investigating the most
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SELECT FirstName , LastName FROM db
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99 Chapter 3: Query Plan Metadata C
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Listing 3.14: Finding the CPU-inten
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WHERE execText.text like '%account%
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115 Chapter 4: Transactions We'll a
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117 Chapter 4: Transactions unique
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Snapshot isolation level 119 Chapte
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121 Chapter 4: Transactions • res
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Lock types 123 Chapter 4: Transacti
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125 Chapter 4: Transactions • Sha
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127 Chapter 4: Transactions SELECT
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129 Chapter 4: Transactions If, fro
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131 Chapter 4: Transactions The LEF
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133 Chapter 4: Transactions When in
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135 Chapter 4: Transactions column.
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137 Chapter 4: Transactions some po
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139 Chapter 4: Transactions OPENTRA
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Page 189 and 190: Identify inefficient indexes Chapte
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Chapter 6: Physical Disk Statistics
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Viewing pending I/O requests Chapte
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Amount of data read versus written
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The results are as follows: Chapter
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263 Chapter 7: OS and Hardware Inte
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Finding the most common waits 267 C
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WHERE cntr_type = @PERF_COUNTER_LAR
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DECLARE @PERF_LARGE_RAW_FRACTION IN
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ORDER BY dopc_fraction.object_name
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) time DATETIME DEFAULT ( GETDATE()
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DECLARE @PERF_AVERAGE_BULK INT , @P
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• cpu_count - number of logical p
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The max worker threads option. 293
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• work_queue_count - number of ta
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WHERE scheduler_id < 255 AND runnab
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System-wide memory use 303 Chapter
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As stated by Books Online: 307 Chap
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Summary 319 Chapter 7: OS and Hardw
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Index A ACID test 116 Activity and
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P Performance counters 277-291 aver
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sys.dm_tran_database_transactions 1
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SQL Compare ® Pro Compare and sync
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Deployment Manager Automated deploy
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SQL Monitor from $795 SQL Server pe
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You can buy our acclaimed SQL Serve
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.NET Reflector Decompile, debug, an
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