SQL Server健康檢查

原創 rise51 2020-07-02 14:05

SQL Server健康檢查的重要性

對一臺新的或不熟悉的服務器，你首先要做的是收集儘可能多有關Server的信息，從硬件和存儲子系統的細節，到OS，再到SQL Server實例本身。你需要知道要處理什麼事情----配置是否差，存儲子系統完全不充分的過時Server，或者，希望一些東西更佳。對於把精力放在正確管理和優化數據庫Server，這份信息是一個關鍵的開始點。作爲一個數據庫專業人士，實在沒有理由不清楚每臺數據庫Server的硬件及配置信息。

這個章節會通過一套查詢帶你做SQL Server健康檢查，解釋其含義及如何理解結果。這些查詢從硬件和實例層次上開始，然後讓你能夠鑽取到一個特定數據庫，去採集更多特定信息。

很多DBA收集這類信息的一個攔路虎是官僚主義。系統管理員或系統工程師提供並管理實際的數據庫Server硬件和OS，SAN管理員常常負責存儲子系統。這些人員中，常有職稱高於你，而對SQL Server基本不懂的人，成爲你收集有關數據庫Server重要信息的一大障礙。他們或許會把信息採集看成是入侵他們的領域，因此不願意配合你。

不管任何官僚主義還是組織障礙，你仍然可以通過技術在SSMS中收集大部分你需要的信息來做比較全面的SQL Server健康檢查。其中最有用、易用的技術是使用DM和DMF來收集服務器、實例及數據庫有關健康檢查的信息。

運行DMV和DMF查詢

要運行大多數的DMV和DMF查詢，你需要對SQL Server實例有VIEW SERVER STATE權限。

首先你要想準確地找出SQL Server的版本、版次及建立，還想知道是x64還是x86、OS是什麼。很簡單，直接可以通過如下非DMV查詢得到：

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  1. SELECT @@VERSION AS [SQL Server and OS Version Info];  
SELECT @@VERSION AS [SQL Server and OS Version Info];

知道這些信息後，有助於瞭解SQL Server的可用功能。例如，企業版有數據壓縮，而標準版或BI版的SQL Server 2012就不能使用數據壓縮。

SQL Server 創建
微軟定期發佈SQL Server的累積更新（CU-Cumulative Update），每個更新有10~40個熱補丁，以集成的安裝包發佈。

下面這個查詢，能夠獲取數據庫Server上有關OS、語言等更多信息：

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  1. SELECT windows_release, windows_service_pack_level,windows_sku, os_language_version FROM sys.dm_os_windows_info WITH (NOLOCK) OPTION (RECOMPILE);  
SELECT windows_release, windows_service_pack_level,windows_sku, os_language_version FROM sys.dm_os_windows_info WITH (NOLOCK) OPTION (RECOMPILE);

下面的查詢會告訴你有多少邏輯處理器、處理器的超線程比率、有多少物力CPU及多大物理內存。

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  1. -- Hardware information from SQL Server 2012 (new virtual_machine_type_desc)(Cannot distinguish between HT and multi-core)  
  2. SELECT cpu_count AS [Logical CPU Count], hyperthread_ratio AS [HyperthreadRatio],cpu_count/hyperthread_ratio AS [Physical CPU Count],  
  3. physical_memory_kb/1024 AS [Physical Memory (MB)],affinity_type_desc, virtual_machine_type_desc, sqlserver_start_time  
  4. FROM sys.dm_os_sys_info WITH (NOLOCK) OPTION (RECOMPILE);  
  5. -- Gives you some good basic hardware information about your database server  
-- Hardware information from SQL Server 2012 (new virtual_machine_type_desc)(Cannot distinguish between HT and multi-core)
SELECT cpu_count AS [Logical CPU Count], hyperthread_ratio AS [HyperthreadRatio],cpu_count/hyperthread_ratio AS [Physical CPU Count],
physical_memory_kb/1024 AS [Physical Memory (MB)],affinity_type_desc, virtual_machine_type_desc, sqlserver_start_time
FROM sys.dm_os_sys_info WITH (NOLOCK) OPTION (RECOMPILE);
-- Gives you some good basic hardware information about your database server

下面的查詢會讀取SQL Server錯誤日誌，以獲取廠商及數據庫Server的型號（model number）：

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  1. -- Get System Manufacturer and model number from SQL Server Error log. This query might take a few seconds  
  2. -- if you have not recycled your error log recently  
  3. EXEC xp_readerrorlog 0,1,"Manufacturer";  
  4. -- This can help you determine the capabilities and capacities of your database server  
-- Get System Manufacturer and model number from SQL Server Error log. This query might take a few seconds
-- if you have not recycled your error log recently
EXEC xp_readerrorlog 0,1,"Manufacturer";
-- This can help you determine the capabilities and capacities of your database server

知道廠商和型號，你就能找到重要的信息，如有多少處理器插槽、有多少內存插槽，多少及何種類型的PCI-E擴展槽，還會告訴你處理器類型（Intel還是AMD）和處理器是那一代。

下面的查詢會返回處理器的描述及來自Windows Registry的額定時鐘頻率：

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  1. -- Get processor description from Windows Registry  
  2. EXEC xp_instance_regread 'HKEY_LOCAL_MACHINE','HARDWARE\DESCRIPTION\System\CentralProcessor\0','ProcessorNameString';  
  3. -- Gives you the model number and rated clock speed of your processor(s)  
-- Get processor description from Windows Registry
EXEC xp_instance_regread 'HKEY_LOCAL_MACHINE','HARDWARE\DESCRIPTION\System\CentralProcessor\0','ProcessorNameString';
-- Gives you the model number and rated clock speed of your processor(s)

知道額定時鐘頻率非常重要，因爲你的處理器可能因爲電源管理，不是每次都全速運行。Windows Server 2008(R2)使用Balanced Windows Power Plan。這意味着當處理器不在高負荷的情況下，會降低時鐘速率來減少節省電力。當處理器突遇高負載時，它會增加時鐘速率以達到全速，但這不會立即發生從而對查詢性能有負面影響。當使用默認的Balanced Windows Power Plan，而不是High Performance電源計劃，通常OLTP負載下只有20~25%的速率。要避免這樣的問題，你首先要確認你的數據庫Server使用High Performance電源計劃，而不是Balanced電源計劃。這個設置可以動態改變，不需要重啓Windows。其次，使用cpuid.com提供的CPU-Z免費工具確定實際的時鐘速率。如果你使用高性能電源計劃且處理器仍然美歐全速運行，那麼你需要進入系統BIOS去改變電源管理設置，要麼OS控制，要麼完全禁用。

下面的查詢會返回安裝哪些SQL Server服務及其如何配置的信息：

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  1. -- SQL Server Services information from SQL Server 2012  
  2. SELECT servicename, startup_type_desc, status_desc,last_startup_time, service_account, is_clustered, cluster_nodename  
  3. FROM sys.dm_server_services WITH (NOLOCK) OPTION (RECOMPILE);  
  4. -- Gives you information about your installed SQL Server Services, whether they are clustered, and which node owns the cluster resources  
-- SQL Server Services information from SQL Server 2012
SELECT servicename, startup_type_desc, status_desc,last_startup_time, service_account, is_clustered, cluster_nodename
FROM sys.dm_server_services WITH (NOLOCK) OPTION (RECOMPILE);
-- Gives you information about your installed SQL Server Services, whether they are clustered, and which node owns the cluster resources

下面的查詢獲取SQL Server錯誤日誌相關的信息，事先知道錯誤日誌的路徑等有助於在必要時去查閱：

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  1. -- Shows you where the SQL Server error log is located and how it is configured  
  2. SELECT is_enabled, [path], max_size, max_files  
  3. FROM sys.dm_os_server_diagnostics_log_configurations WITH (NOLOCK) OPTION (RECOMPILE);  
  4. -- Knowing this information is important for troubleshooting purposes  
-- Shows you where the SQL Server error log is located and how it is configured
SELECT is_enabled, [path], max_size, max_files
FROM sys.dm_os_server_diagnostics_log_configurations WITH (NOLOCK) OPTION (RECOMPILE);
-- Knowing this information is important for troubleshooting purposes

下面的查詢會返回是否你的數據庫Server使用了Windows Clustering：

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  1. -- Get information about your OS cluster  
  2. --(if your database server is in a cluster)  
  3. SELECT VerboseLogging, SqlDumperDumpFlags, SqlDumperDumpPath,SqlDumperDumpTimeOut, FailureConditionLevel, HealthCheckTimeout  
  4. FROM sys.dm_os_cluster_properties WITH (NOLOCK) OPTION (RECOMPILE);  
  5. -- You will see no results if your instance is not clustered  
-- Get information about your OS cluster
--(if your database server is in a cluster)
SELECT VerboseLogging, SqlDumperDumpFlags, SqlDumperDumpPath,SqlDumperDumpTimeOut, FailureConditionLevel, HealthCheckTimeout
FROM sys.dm_os_cluster_properties WITH (NOLOCK) OPTION (RECOMPILE);
-- You will see no results if your instance is not clustered

如果你使用羣集，你可以使用下面的查詢來獲取有關羣集節點的有用信息：

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  1. -- Get information about your cluster nodes and their status (if your database server is in a cluster)  
  2. SELECT NodeName, status_description, is_current_owner  
  3. FROM sys.dm_os_cluster_nodes WITH (NOLOCK) OPTION (RECOMPILE);  
  4. -- Knowing which node owns the cluster resources is critical Especially when you are installing Windows or SQL Server updates  
-- Get information about your cluster nodes and their status (if your database server is in a cluster)
SELECT NodeName, status_description, is_current_owner
FROM sys.dm_os_cluster_nodes WITH (NOLOCK) OPTION (RECOMPILE);
-- Knowing which node owns the cluster resources is critical Especially when you are installing Windows or SQL Server updates

下面的查詢收集有關SQL Server實例配置的額外信息，你可以使用sp_configure來改變屬性：

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  1. -- Get configuration values for instance  
  2. SELECT name, value, value_in_use, [description] FROM sys.configurations WITH (NOLOCK) ORDER BY name OPTION (RECOMPILE);  
  3. -- Focus on backup compression default  
  4. -- clr enabled (only enable if it is needed)  
  5. -- lightweight pooling (should be zero)  
  6. -- max degree of parallelism  
  7. -- max server memory (MB) (set to an appropriate value)  
  8. -- optimize for ad hoc workloads (should be 1)  
  9. -- priority boost (should be zero)  
-- Get configuration values for instance
SELECT name, value, value_in_use, [description] FROM sys.configurations WITH (NOLOCK) ORDER BY name OPTION (RECOMPILE);
-- Focus on backup compression default
-- clr enabled (only enable if it is needed)
-- lightweight pooling (should be zero)
-- max degree of parallelism
-- max server memory (MB) (set to an appropriate value)
-- optimize for ad hoc workloads (should be 1)
-- priority boost (should be zero)

下面的查詢返回網絡配置相關的一點信息，對於處理網絡、防火牆相關的問題有幫助：

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  1. -- Get information about TCP Listener for SQL Server  
  2. SELECT listener_id, ip_address, is_ipv4, port, type_desc, state_desc, start_time  
  3. FROM sys.dm_tcp_listener_states WITH (NOLOCK) OPTION (RECOMPILE);  
  4. -- Helpful for network and connectivity troubleshooting  
-- Get information about TCP Listener for SQL Server
SELECT listener_id, ip_address, is_ipv4, port, type_desc, state_desc, start_time
FROM sys.dm_tcp_listener_states WITH (NOLOCK) OPTION (RECOMPILE);
-- Helpful for network and connectivity troubleshooting

下面的查詢返回來自Windows註冊表SQL Server相關的信息：

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  1. -- SQL Server Registry information  
  2. SELECT registry_key, value_name, value_data  
  3. FROM sys.dm_server_registry WITH (NOLOCK) OPTION (RECOMPILE);  
  4. -- This lets you safely read some SQL Server related information from the Windows Registry  
-- SQL Server Registry information
SELECT registry_key, value_name, value_data
FROM sys.dm_server_registry WITH (NOLOCK) OPTION (RECOMPILE);
-- This lets you safely read some SQL Server related information from the Windows Registry

下面的查詢返回是否SQL Server實例產生內存轉儲：

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  1. -- Get information on location, time and size of any memory dumps from SQL Server  
  2. SELECT [filename], creation_time, size_in_bytes  
  3. FROM sys.dm_server_memory_dumps WITH (NOLOCK) OPTION (RECOMPILE);  
  4. -- This will not return any rows if you have not had any memory dumps (which is a good thing)  
-- Get information on location, time and size of any memory dumps from SQL Server
SELECT [filename], creation_time, size_in_bytes
FROM sys.dm_server_memory_dumps WITH (NOLOCK) OPTION (RECOMPILE);
-- This will not return any rows if you have not had any memory dumps (which is a good thing)

下面的查詢返回SQL Server實例有多少在運行的數據庫，它們位於哪裏：

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  1. -- File Names and Paths for Tempdb and all user databases in instance  
  2. SELECT DB_NAME([database_id])AS [Database Name],  
  3. [file_id], name, physical_name, type_desc, state_desc,  
  4. CONVERT( bigint, size/128.0) AS [Total Size in MB]  
  5. FROM sys.master_files WITH (NOLOCK)  
  6. WHERE [database_id] > 4  
  7. AND [database_id] <> 32767  
  8. OR [database_id] = 2  
  9. ORDER BY DB_NAME([database_id]) OPTION (RECOMPILE);  
  10. -- Things to look at:  
  11. -- Are data files and log files on different drives?  
  12. -- Is everything on the C: drive?  
  13. -- Is TempDB on dedicated drives?  
  14. -- Are there multiple data files?  
-- File Names and Paths for Tempdb and all user databases in instance
SELECT DB_NAME([database_id])AS [Database Name],
[file_id], name, physical_name, type_desc, state_desc,
CONVERT( bigint, size/128.0) AS [Total Size in MB]
FROM sys.master_files WITH (NOLOCK)
WHERE [database_id] > 4
AND [database_id] <> 32767
OR [database_id] = 2
ORDER BY DB_NAME([database_id]) OPTION (RECOMPILE);
-- Things to look at:
-- Are data files and log files on different drives?
-- Is everything on the C: drive?
-- Is TempDB on dedicated drives?
-- Are there multiple data files?

下面的查詢返回實例上所有數據庫的一些關鍵屬性：

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  1. -- Recovery model, log reuse wait description, log file size, log usage size  
  2. -- and compatibility level for all databases on instance  
  3. SELECT db.[name] AS [Database Name], db.recovery_model_desc AS [Recovery Model],  
  4. db.log_reuse_wait_desc AS [Log Reuse Wait Description],  
  5. ls.cntr_value AS [Log Size (KB)], lu.cntr_value AS [Log Used (KB)],  
  6. CAST(CAST(lu.cntr_value AS FLOAT) / CAST(ls.cntr_value AS FLOAT)AS DECIMAL(18,2)) *  
  7. 100 AS  
  8. [Log Used %], db.[compatibility_level] AS [DB Compatibility Level],  
  9. db.page_verify_option_desc AS [Page Verify Option], db.is_auto_create_stats_on,  
  10. db.is_auto_update_stats_on, db.is_auto_update_stats_async_on,  
  11. db.is_parameterization_forced,  
  12. db.snapshot_isolation_state_desc, db.is_read_committed_snapshot_on,  
  13. is_auto_shrink_on, is_auto_close_on  
  14. FROM sys.databases AS db WITH (NOLOCK)  
  15. INNER JOIN sys.dm_os_performance_counters AS lu WITH (NOLOCK)  
  16. ON db.name = lu.instance_name  
  17. INNER JOIN sys.dm_os_performance_counters AS ls WITH (NOLOCK)  
  18. ON db.name = ls.instance_name  
  19. WHERE lu.counter_name LIKE N'Log File(s) Used Size (KB)%'  
  20. AND ls.counter_name LIKE N'Log File(s) Size (KB)%'  
  21. AND ls.cntr_value > 0 OPTION (RECOMPILE);  
  22. -- Things to look at:  
  23. -- How many databases are on the instance?  
  24. -- What recovery models are they using?  
  25. -- What is the log reuse wait description?  
  26. -- How full are the transaction logs ?  
  27. -- What compatibility level are they on?  
-- Recovery model, log reuse wait description, log file size, log usage size
-- and compatibility level for all databases on instance
SELECT db.[name] AS [Database Name], db.recovery_model_desc AS [Recovery Model],
db.log_reuse_wait_desc AS [Log Reuse Wait Description],
ls.cntr_value AS [Log Size (KB)], lu.cntr_value AS [Log Used (KB)],
CAST(CAST(lu.cntr_value AS FLOAT) / CAST(ls.cntr_value AS FLOAT)AS DECIMAL(18,2)) *
100 AS
[Log Used %], db.[compatibility_level] AS [DB Compatibility Level],
db.page_verify_option_desc AS [Page Verify Option], db.is_auto_create_stats_on,
db.is_auto_update_stats_on, db.is_auto_update_stats_async_on,
db.is_parameterization_forced,
db.snapshot_isolation_state_desc, db.is_read_committed_snapshot_on,
is_auto_shrink_on, is_auto_close_on
FROM sys.databases AS db WITH (NOLOCK)
INNER JOIN sys.dm_os_performance_counters AS lu WITH (NOLOCK)
ON db.name = lu.instance_name
INNER JOIN sys.dm_os_performance_counters AS ls WITH (NOLOCK)
ON db.name = ls.instance_name
WHERE lu.counter_name LIKE N'Log File(s) Used Size (KB)%'
AND ls.counter_name LIKE N'Log File(s) Size (KB)%'
AND ls.cntr_value > 0 OPTION (RECOMPILE);
-- Things to look at:
-- How many databases are on the instance?
-- What recovery models are they using?
-- What is the log reuse wait description?
-- How full are the transaction logs ?
-- What compatibility level are they on?

下面的查詢返回哪個數據庫文件有最大的I/O延遲：

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  1. -- Calculates average stalls per read, per write,  
  2. -- and per total input/output for each database file.  
  3. SELECT DB_NAME(fs.database_id) AS [Database Name], mf.physical_name,  
  4. io_stall_read_ms, num_of_reads,  
  5. CAST(io_stall_read_ms/(1.0 + num_of_reads) AS NUMERIC(10,1)) AS  
  6. [avg_read_stall_ms],io_stall_write_ms,  
  7. num_of_writes,CAST(io_stall_write_ms/(1.0+num_of_writes) AS NUMERIC(10,1)) AS  
  8. [avg_write_stall_ms],  
  9. io_stall_read_ms + io_stall_write_ms AS [io_stalls], num_of_reads + num_of_writes  
  10. AS [total_io],  
  11. CAST((io_stall_read_ms + io_stall_write_ms)/(1.0 + num_of_reads + num_of_writes) AS  
  12. NUMERIC(10,1))  
  13. AS [avg_io_stall_ms]  
  14. FROM sys.dm_io_virtual_file_stats(null,null) AS fs  
  15. INNER JOIN sys.master_files AS mf WITH (NOLOCK)  
  16. ON fs.database_id = mf.database_id  
  17. AND fs.[file_id] = mf.[file_id]  
  18. ORDER BY avg_io_stall_ms DESC OPTION (RECOMPILE);  
  19. -- Helps determine which database files on  
  20. -- the entire instance have the most I/O bottlenecks  
-- Calculates average stalls per read, per write,
-- and per total input/output for each database file.
SELECT DB_NAME(fs.database_id) AS [Database Name], mf.physical_name,
io_stall_read_ms, num_of_reads,
CAST(io_stall_read_ms/(1.0 + num_of_reads) AS NUMERIC(10,1)) AS
[avg_read_stall_ms],io_stall_write_ms,
num_of_writes,CAST(io_stall_write_ms/(1.0+num_of_writes) AS NUMERIC(10,1)) AS
[avg_write_stall_ms],
io_stall_read_ms + io_stall_write_ms AS [io_stalls], num_of_reads + num_of_writes
AS [total_io],
CAST((io_stall_read_ms + io_stall_write_ms)/(1.0 + num_of_reads + num_of_writes) AS
NUMERIC(10,1))
AS [avg_io_stall_ms]
FROM sys.dm_io_virtual_file_stats(null,null) AS fs
INNER JOIN sys.master_files AS mf WITH (NOLOCK)
ON fs.database_id = mf.database_id
AND fs.[file_id] = mf.[file_id]
ORDER BY avg_io_stall_ms DESC OPTION (RECOMPILE);
-- Helps determine which database files on
-- the entire instance have the most I/O bottlenecks

如果遇到I/O瓶頸，你可以使用Windows Performance Monitor查看邏輯磁盤的Avg Disk Sec/Write和 Avg Disk Sec/Read等計數器。根據存儲的類型，通過增加更多的spindle、改變RAID控制器高速緩存策略或改變RAID級別或許可以改善I/O性能。如果可能的話，你也可以考慮移除一些數據文件到其他磁盤。

下面的查詢返回佔用最多內存的用戶數據庫：

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  1. -- Get total buffer usage by database for current instance  
  2. SELECT DB_NAME(database_id) AS [Database Name],  
  3. COUNT(*) * 8/1024.0 AS [Cached Size (MB)]  
  4. FROM sys.dm_os_buffer_descriptors WITH (NOLOCK)  
  5. WHERE database_id > 4 -- system databases  
  6. AND database_id <> 32767 -- ResourceDB  
  7. GROUP BY DB_NAME(database_id)  
  8. ORDER BY [Cached Size (MB)] DESC OPTION (RECOMPILE);  
  9. -- Tells you how much memory (in the buffer pool)  
  10. -- is being used by each database on the instance  
-- Get total buffer usage by database for current instance
SELECT DB_NAME(database_id) AS [Database Name],
COUNT(*) * 8/1024.0 AS [Cached Size (MB)]
FROM sys.dm_os_buffer_descriptors WITH (NOLOCK)
WHERE database_id > 4 -- system databases
AND database_id <> 32767 -- ResourceDB
GROUP BY DB_NAME(database_id)
ORDER BY [Cached Size (MB)] DESC OPTION (RECOMPILE);
-- Tells you how much memory (in the buffer pool)
-- is being used by each database on the instance

下面的查詢返回使用最多處理器時間的用戶數據庫：

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  1. -- Get CPU utilization by database  
  2. WITH DB_CPU_Stats  
  3. AS  
  4. (SELECT DatabaseID, DB_Name(DatabaseID) AS [DatabaseName],  
  5. SUM(total_worker_time) AS [CPU_Time_Ms]  
  6. FROM sys.dm_exec_query_stats AS qs  
  7. CROSS APPLY (SELECT CONVERT(int, value) AS [DatabaseID]  
  8. FROM sys.dm_exec_plan_attributes(qs.plan_handle)  
  9. WHERE attribute = N'dbid') AS F_DB  
  10. GROUP BY DatabaseID)  
  11. SELECT ROW_NUMBER() OVER(ORDER BY [CPU_Time_Ms] DESC) AS [row_num],  
  12. DatabaseName, [CPU_Time_Ms],  
  13. CAST([CPU_Time_Ms] * 1.0 / SUM([CPU_Time_Ms])  
  14. OVER() * 100.0 AS DECIMAL(5, 2)) AS [CPUPercent]  
  15. FROM DB_CPU_Stats  
  16. WHERE DatabaseID > 4 -- system databases  
  17. AND DatabaseID <> 32767 -- ResourceDB  
  18. ORDER BY row_num OPTION (RECOMPILE);  
  19. -- Helps determine which database is using the most CPU resources on the instance  
-- Get CPU utilization by database
WITH DB_CPU_Stats
AS
(SELECT DatabaseID, DB_Name(DatabaseID) AS [DatabaseName],
SUM(total_worker_time) AS [CPU_Time_Ms]
FROM sys.dm_exec_query_stats AS qs
CROSS APPLY (SELECT CONVERT(int, value) AS [DatabaseID]
FROM sys.dm_exec_plan_attributes(qs.plan_handle)
WHERE attribute = N'dbid') AS F_DB
GROUP BY DatabaseID)
SELECT ROW_NUMBER() OVER(ORDER BY [CPU_Time_Ms] DESC) AS [row_num],
DatabaseName, [CPU_Time_Ms],
CAST([CPU_Time_Ms] * 1.0 / SUM([CPU_Time_Ms])
OVER() * 100.0 AS DECIMAL(5, 2)) AS [CPUPercent]
FROM DB_CPU_Stats
WHERE DatabaseID > 4 -- system databases
AND DatabaseID <> 32767 -- ResourceDB
ORDER BY row_num OPTION (RECOMPILE);
-- Helps determine which database is using the most CPU resources on the instance

下面的查詢返回SQL Server上次重啓或使用DBCC SQLPERF ('sys.dm_os_wait_stats', CLEAR)以來，最高的累計等待統計：

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  1. -- Isolate top waits for server instance since last restart or statistics clear  
  2. WITH Waits AS  
  3. (SELECT wait_type, wait_time_ms / 1000. AS wait_time_s,  
  4. 100. * wait_time_ms / SUM(wait_time_ms) OVER() AS pct,  
  5. ROW_NUMBER() OVER(ORDER BY wait_time_ms DESC) AS rn  
  6. FROM sys.dm_os_wait_stats WITH (NOLOCK)  
  7. WHERE wait_type NOT IN (N'CLR_SEMAPHORE',N'LAZYWRITER_SLEEP',N'RESOURCE_QUEUE',  
  8. N'SLEEP_TASK',N'SLEEP_SYSTEMTASK',N'SQLTRACE_BUFFER_FLUSH',N'WAITFOR',  
  9. N'LOGMGR_QUEUE',N'CHECKPOINT_QUEUE', N'REQUEST_FOR_DEADLOCK_SEARCH',  
  10. N'XE_TIMER_EVENT',N'BROKER_TO_FLUSH',N'BROKER_TASK_STOP',N'CLR_MANUAL_EVENT',  
  11. N'CLR_AUTO_EVENT',N'DISPATCHER_QUEUE_SEMAPHORE', N'FT_IFTS_SCHEDULER_IDLE_WAIT',  
  12. N'XE_DISPATCHER_WAIT', N'XE_DISPATCHER_JOIN', N'SQLTRACE_INCREMENTAL_FLUSH_SLEEP',  
  13. N'ONDEMAND_TASK_QUEUE', N'BROKER_EVENTHANDLER', N'SLEEP_BPOOL_FLUSH',  
  14. N'DIRTY_PAGE_POLL', N'HADR_FILESTREAM_IOMGR_IOCOMPLETION',  
  15. N'SP_SERVER_DIAGNOSTICS_SLEEP'))  
  16. SELECT W1.wait_type,  
  17. CAST(W1.wait_time_s AS DECIMAL(12, 2)) AS wait_time_s,  
  18. CAST(W1.pct AS DECIMAL(12, 2)) AS pct,  
  19. CAST(SUM(W2.pct) AS DECIMAL(12, 2)) AS running_pct  
  20. FROM Waits AS W1  
  21. INNER JOIN Waits AS W2  
  22. ON W2.rn <= W1.rn  
  23. GROUP BY W1.rn, W1.wait_type, W1.wait_time_s, W1.pct  
  24. HAVING SUM(W2.pct) - W1.pct < 99 OPTION (RECOMPILE); -- percentage threshold  
  25. -- Clear Wait Stats  
  26. -- DBCC SQLPERF('sys.dm_os_wait_stats', CLEAR);  
-- Isolate top waits for server instance since last restart or statistics clear
WITH Waits AS
(SELECT wait_type, wait_time_ms / 1000. AS wait_time_s,
100. * wait_time_ms / SUM(wait_time_ms) OVER() AS pct,
ROW_NUMBER() OVER(ORDER BY wait_time_ms DESC) AS rn
FROM sys.dm_os_wait_stats WITH (NOLOCK)
WHERE wait_type NOT IN (N'CLR_SEMAPHORE',N'LAZYWRITER_SLEEP',N'RESOURCE_QUEUE',
N'SLEEP_TASK',N'SLEEP_SYSTEMTASK',N'SQLTRACE_BUFFER_FLUSH',N'WAITFOR',
N'LOGMGR_QUEUE',N'CHECKPOINT_QUEUE', N'REQUEST_FOR_DEADLOCK_SEARCH',
N'XE_TIMER_EVENT',N'BROKER_TO_FLUSH',N'BROKER_TASK_STOP',N'CLR_MANUAL_EVENT',
N'CLR_AUTO_EVENT',N'DISPATCHER_QUEUE_SEMAPHORE', N'FT_IFTS_SCHEDULER_IDLE_WAIT',
N'XE_DISPATCHER_WAIT', N'XE_DISPATCHER_JOIN', N'SQLTRACE_INCREMENTAL_FLUSH_SLEEP',
N'ONDEMAND_TASK_QUEUE', N'BROKER_EVENTHANDLER', N'SLEEP_BPOOL_FLUSH',
N'DIRTY_PAGE_POLL', N'HADR_FILESTREAM_IOMGR_IOCOMPLETION',
N'SP_SERVER_DIAGNOSTICS_SLEEP'))
SELECT W1.wait_type,
CAST(W1.wait_time_s AS DECIMAL(12, 2)) AS wait_time_s,
CAST(W1.pct AS DECIMAL(12, 2)) AS pct,
CAST(SUM(W2.pct) AS DECIMAL(12, 2)) AS running_pct
FROM Waits AS W1
INNER JOIN Waits AS W2
ON W2.rn <= W1.rn
GROUP BY W1.rn, W1.wait_type, W1.wait_time_s, W1.pct
HAVING SUM(W2.pct) - W1.pct < 99 OPTION (RECOMPILE); -- percentage threshold
-- Clear Wait Stats
-- DBCC SQLPERF('sys.dm_os_wait_stats', CLEAR);

博客http://blogs.msdn.com/b/psssql/archive/2009/11/03/the-sql-server-wait-type-repository.aspx裏介紹了很多等待類型。

下面的查詢返回實例上累積的信號（CPU）等待：

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  1. -- Signal Waits for instance  
  2. SELECT CAST(100.0 * SUM(signal_wait_time_ms) / SUM (wait_time_ms) AS NUMERIC(20,2))  
  3. AS [%signal (cpu) waits],  
  4. CAST(100.0 * SUM(wait_time_ms - signal_wait_time_ms) / SUM (wait_time_ms) AS  
  5. NUMERIC(20,2)) AS [%resource waits]  
  6. FROM sys.dm_os_wait_stats WITH (NOLOCK) OPTION (RECOMPILE);  
  7. -- Signal Waits above 15-20% is usually a sign of CPU pressure  
-- Signal Waits for instance
SELECT CAST(100.0 * SUM(signal_wait_time_ms) / SUM (wait_time_ms) AS NUMERIC(20,2))
AS [%signal (cpu) waits],
CAST(100.0 * SUM(wait_time_ms - signal_wait_time_ms) / SUM (wait_time_ms) AS
NUMERIC(20,2)) AS [%resource waits]
FROM sys.dm_os_wait_stats WITH (NOLOCK) OPTION (RECOMPILE);
-- Signal Waits above 15-20% is usually a sign of CPU pressure

信號等待是CPU相關的等待。通常信號等待在15~20%就表示CPU壓力。

下面的查詢返回最常連接數據庫的登錄信息：

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  1. -- Get logins that are connected and how many sessions they have  
  2. SELECT login_name, COUNT(session_id) AS [session_count]  
  3. FROM sys.dm_exec_sessions WITH (NOLOCK)  
  4. GROUP BY login_name  
  5. ORDER BY COUNT(session_id) DESC OPTION (RECOMPILE);  
  6. -- This can help characterize your workload and  
  7. -- determine whether you are seeing a normal level of activity  
-- Get logins that are connected and how many sessions they have
SELECT login_name, COUNT(session_id) AS [session_count]
FROM sys.dm_exec_sessions WITH (NOLOCK)
GROUP BY login_name
ORDER BY COUNT(session_id) DESC OPTION (RECOMPILE);
-- This can help characterize your workload and
-- determine whether you are seeing a normal level of activity

下面的查詢返回當前的任務急pending的I/O計數信息，返回的3個值越低越好：

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  1. -- Get Average Task Counts (run multiple times)  
  2. SELECT AVG(current_tasks_count) AS [Avg Task Count],  
  3. AVG(runnable_tasks_count) AS [Avg Runnable Task Count],  
  4. AVG(pending_disk_io_count) AS [Avg Pending DiskIO Count]  
  5. FROM sys.dm_os_schedulers WITH (NOLOCK)  
  6. WHERE scheduler_id < 255 OPTION (RECOMPILE);  
  7. -- Sustained values above 10 suggest further investigation in that area  
  8. -- High Avg Task Counts are often caused by blocking or other resource contention  
  9. -- High Avg Runnable Task Counts are a good sign of CPU pressure  
  10. -- High Avg Pending DiskIO Counts are a sign of disk pressure  
-- Get Average Task Counts (run multiple times)
SELECT AVG(current_tasks_count) AS [Avg Task Count],
AVG(runnable_tasks_count) AS [Avg Runnable Task Count],
AVG(pending_disk_io_count) AS [Avg Pending DiskIO Count]
FROM sys.dm_os_schedulers WITH (NOLOCK)
WHERE scheduler_id < 255 OPTION (RECOMPILE);
-- Sustained values above 10 suggest further investigation in that area
-- High Avg Task Counts are often caused by blocking or other resource contention
-- High Avg Runnable Task Counts are a good sign of CPU pressure
-- High Avg Pending DiskIO Counts are a sign of disk pressure

下面的查詢返回過去256分鐘CPU使用的歷史狀況，1分鐘一個間隔：

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  1. -- Get CPU Utilization History for last 256 minutes (in one minute intervals)  
  2. -- This version works with SQL Server 2008 and above  
  3. DECLARE @ts_now bigint = (SELECT cpu_ticks/(cpu_ticks/ms_ticks)  
  4. FROM sys.dm_os_sys_info WITH (NOLOCK));  
  5. SELECT TOP(256) SQLProcessUtilization AS [SQL Server Process CPU Utilization],  
  6. SystemIdle AS [System Idle Process],  
  7. 100 - SystemIdle - SQLProcessUtilization  
  8. AS [Other Process CPU Utilization],  
  9. DATEADD(ms, -1 * (@ts_now - [timestamp]),  
  10. GETDATE()) AS [Event Time]  
  11. FROM (SELECT record.value('(./Record/@id)[1]', 'int') AS record_id,  
  12. record.value('(./Record/SchedulerMonitorEvent/SystemHealth/SystemIdle)[1]', 'int')  
  13. AS[SystemIdle],record.value('(./Record/SchedulerMonitorEvent/SystemHealth/  
  14. ProcessUtilization)[1]','int')  
  15. AS [SQLProcessUtilization], [timestamp]  
  16. FROM (SELECT [timestamp], CONVERT(xml, record) AS [record]  
  17. FROM sys.dm_os_ring_buffers WITH (NOLOCK)  
  18. WHERE ring_buffer_type = N'RING_BUFFER_SCHEDULER_MONITOR'  
  19. AND record LIKE N'%<SystemHealth>%') AS x  
  20. ) AS y  
  21. ORDER BY record_id DESC OPTION (RECOMPILE);  
  22. -- Look at the trend over the entire period.  
  23. -- Also look at high sustained Other Process CPU Utilization values  
-- Get CPU Utilization History for last 256 minutes (in one minute intervals)
-- This version works with SQL Server 2008 and above
DECLARE @ts_now bigint = (SELECT cpu_ticks/(cpu_ticks/ms_ticks)
FROM sys.dm_os_sys_info WITH (NOLOCK));
SELECT TOP(256) SQLProcessUtilization AS [SQL Server Process CPU Utilization],
SystemIdle AS [System Idle Process],
100 - SystemIdle - SQLProcessUtilization
AS [Other Process CPU Utilization],
DATEADD(ms, -1 * (@ts_now - [timestamp]),
GETDATE()) AS [Event Time]
FROM (SELECT record.value('(./Record/@id)[1]', 'int') AS record_id,
record.value('(./Record/SchedulerMonitorEvent/SystemHealth/SystemIdle)[1]', 'int')
AS[SystemIdle],record.value('(./Record/SchedulerMonitorEvent/SystemHealth/
ProcessUtilization)[1]','int')
AS [SQLProcessUtilization], [timestamp]
FROM (SELECT [timestamp], CONVERT(xml, record) AS [record]
FROM sys.dm_os_ring_buffers WITH (NOLOCK)
WHERE ring_buffer_type = N'RING_BUFFER_SCHEDULER_MONITOR'
AND record LIKE N'%<SystemHealth>%') AS x
) AS y
ORDER BY record_id DESC OPTION (RECOMPILE);
-- Look at the trend over the entire period.
-- Also look at high sustained Other Process CPU Utilization values

如果Other Process CPU Utilization持續超過5%，你就應該查看什麼在使用CPU。

下面的查詢返回OS級別物理內存的狀況：

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  1. -- Good basic information about OS memory amounts and state  
  2. SELECT total_physical_memory_kb, available_physical_memory_kb,  
  3. total_page_file_kb, available_page_file_kb,  
  4. system_memory_state_desc  
  5. FROM sys.dm_os_sys_memory WITH (NOLOCK) OPTION (RECOMPILE);  
  6. -- You want to see "Available physical memory is high"  
  7. -- This indicates that you are not under external memory pressure  
-- Good basic information about OS memory amounts and state
SELECT total_physical_memory_kb, available_physical_memory_kb,
total_page_file_kb, available_page_file_kb,
system_memory_state_desc
FROM sys.dm_os_sys_memory WITH (NOLOCK) OPTION (RECOMPILE);
-- You want to see "Available physical memory is high"
-- This indicates that you are not under external memory pressure

下面的查詢返回SQL Server的內存使用情況：

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  1. -- SQL Server Process Address space info  
  2. --(shows whether locked pages is enabled, among other things)  
  3. SELECT physical_memory_in_use_kb,locked_page_allocations_kb,  
  4. page_fault_count, memory_utilization_percentage,  
  5. available_commit_limit_kb, process_physical_memory_low,  
  6. process_virtual_memory_low  
  7. FROM sys.dm_os_process_memory WITH (NOLOCK) OPTION (RECOMPILE);  
  8. -- You want to see 0 for process_physical_memory_low  
  9. -- You want to see 0 for process_virtual_memory_low  
  10. -- This indicates that you are not under internal memory pressure  
-- SQL Server Process Address space info
--(shows whether locked pages is enabled, among other things)
SELECT physical_memory_in_use_kb,locked_page_allocations_kb,
page_fault_count, memory_utilization_percentage,
available_commit_limit_kb, process_physical_memory_low,
process_virtual_memory_low
FROM sys.dm_os_process_memory WITH (NOLOCK) OPTION (RECOMPILE);
-- You want to see 0 for process_physical_memory_low
-- You want to see 0 for process_virtual_memory_low
-- This indicates that you are not under internal memory pressure

查看SQL Server是否處於內存壓力的一個經典做法是查看Page Life Expectancy (PLE)，PLE越高越好（MS推薦300爲可接受）：

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  1. -- Page Life Expectancy (PLE) value for default instance  
  2. SELECT cntr_value AS [Page Life Expectancy]  
  3. FROM sys.dm_os_performance_counters WITH (NOLOCK)  
  4. WHERE [object_name] LIKE N'%Buffer Manager%' -- Handles named instances  
  5. AND counter_name = N'Page life expectancy' OPTION (RECOMPILE);  
  6. -- PLE is one way to measure memory pressure.  
  7. -- Higher PLE is better. Watch the trend, not the absolute value.  
-- Page Life Expectancy (PLE) value for default instance
SELECT cntr_value AS [Page Life Expectancy]
FROM sys.dm_os_performance_counters WITH (NOLOCK)
WHERE [object_name] LIKE N'%Buffer Manager%' -- Handles named instances
AND counter_name = N'Page life expectancy' OPTION (RECOMPILE);
-- PLE is one way to measure memory pressure.
-- Higher PLE is better. Watch the trend, not the absolute value.

下面的查詢返回Memory Grants Outstanding：

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  1. -- Memory Grants Outstanding value for default instance  
  2. SELECT cntr_value AS [Memory Grants Outstanding]  
  3. FROM sys.dm_os_performance_counters WITH (NOLOCK)  
  4. WHERE [object_name] LIKE N'%Memory Manager%' -- Handles named instances  
  5. AND counter_name = N'Memory Grants Outstanding' OPTION (RECOMPILE);  
  6. -- Memory Grants Outstanding above zero  
  7. -- for a sustained period is a secondary indicator of memory pressure  
-- Memory Grants Outstanding value for default instance
SELECT cntr_value AS [Memory Grants Outstanding]
FROM sys.dm_os_performance_counters WITH (NOLOCK)
WHERE [object_name] LIKE N'%Memory Manager%' -- Handles named instances
AND counter_name = N'Memory Grants Outstanding' OPTION (RECOMPILE);
-- Memory Grants Outstanding above zero
-- for a sustained period is a secondary indicator of memory pressure

下面的查詢返回Memory Grants Pending：

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  1. -- Memory Grants Pending value for default instance  
  2. SELECT cntr_value AS [Memory Grants Pending]  
  3. FROM sys.dm_os_performance_counters WITH (NOLOCK)  
  4. WHERE [object_name] LIKE N'%Memory Manager%' -- Handles named instances  
  5. AND counter_name = N'Memory Grants Pending' OPTION (RECOMPILE);  
  6. -- Memory Grants Pending above zero  
  7. -- for a sustained period is an extremely strong indicator of memory pressure  
-- Memory Grants Pending value for default instance
SELECT cntr_value AS [Memory Grants Pending]
FROM sys.dm_os_performance_counters WITH (NOLOCK)
WHERE [object_name] LIKE N'%Memory Manager%' -- Handles named instances
AND counter_name = N'Memory Grants Pending' OPTION (RECOMPILE);
-- Memory Grants Pending above zero
-- for a sustained period is an extremely strong indicator of memory pressure

當你從上面3個查詢中看到任何內存壓力，要進一步查看整體的內存使用狀況：

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  1. -- Memory Clerk Usage for instance  
  2. -- Look for high value for CACHESTORE_SQLCP (Ad-hoc query plans)  
  3. SELECT TOP(10) [type] AS [Memory Clerk Type],  
  4. SUM(pages_kb) AS [SPA Mem, Kb]  
  5. FROM sys.dm_os_memory_clerks WITH (NOLOCK)  
  6. GROUP BY [type]  
  7. ORDER BY SUM(pages_kb) DESC OPTION (RECOMPILE);  
  8. -- CACHESTORE_SQLCP SQL Plans  
  9. -- These are cached SQL statements or batches that  
  10. -- aren't in stored procedures, functions and triggers  
  11. --  
  12. -- CACHESTORE_OBJCP Object Plans  
  13. -- These are compiled plans for  
  14. -- stored procedures, functions and triggers  
  15. --  
  16. -- CACHESTORE_PHDR Algebrizer Trees  
  17. -- An algebrizer tree is the parsed SQL text  
  18. -- that resolves the table and column names  
-- Memory Clerk Usage for instance
-- Look for high value for CACHESTORE_SQLCP (Ad-hoc query plans)
SELECT TOP(10) [type] AS [Memory Clerk Type],
SUM(pages_kb) AS [SPA Mem, Kb]
FROM sys.dm_os_memory_clerks WITH (NOLOCK)
GROUP BY [type]
ORDER BY SUM(pages_kb) DESC OPTION (RECOMPILE);
-- CACHESTORE_SQLCP SQL Plans
-- These are cached SQL statements or batches that
-- aren't in stored procedures, functions and triggers
--
-- CACHESTORE_OBJCP Object Plans
-- These are compiled plans for
-- stored procedures, functions and triggers
--
-- CACHESTORE_PHDR Algebrizer Trees
-- An algebrizer tree is the parsed SQL text
-- that resolves the table and column names

如果你看到CACHESTORE_SQLCP memory clerk使用很多內存，那麼你可以確定在Procedure緩存裏是否有很多隻用一次且佔用了大量內存的ad hoc查詢計劃：

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  1. -- Find single-use, ad-hoc queries that are bloating the plan cache  
  2. SELECT TOP(20) [text] AS [QueryText], cp.size_in_bytes  
  3. FROM sys.dm_exec_cached_plans AS cp WITH (NOLOCK)  
  4. CROSS APPLY sys.dm_exec_sql_text(plan_handle)  
  5. WHERE cp.cacheobjtype = N'Compiled Plan'  
  6. AND cp.objtype = N'Adhoc'  
  7. AND cp.usecounts = 1  
  8. ORDER BY cp.size_in_bytes DESC OPTION (RECOMPILE);  
  9. -- Gives you the text and size of single-use ad-hoc queries that  
  10. -- waste space in the plan cache  
  11. -- Enabling 'optimize for ad hoc workloads' for the instance  
  12. -- can help (SQL Server 2008 and above only)  
  13. -- Enabling forced parameterization for the database can help, but test first!  
-- Find single-use, ad-hoc queries that are bloating the plan cache
SELECT TOP(20) [text] AS [QueryText], cp.size_in_bytes
FROM sys.dm_exec_cached_plans AS cp WITH (NOLOCK)
CROSS APPLY sys.dm_exec_sql_text(plan_handle)
WHERE cp.cacheobjtype = N'Compiled Plan'
AND cp.objtype = N'Adhoc'
AND cp.usecounts = 1
ORDER BY cp.size_in_bytes DESC OPTION (RECOMPILE);
-- Gives you the text and size of single-use ad-hoc queries that
-- waste space in the plan cache
-- Enabling 'optimize for ad hoc workloads' for the instance
-- can help (SQL Server 2008 and above only)
-- Enabling forced parameterization for the database can help, but test first!

數據庫級別的查詢

切換到特定用戶數據庫：

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  1. -- Database specific queries ******************************************************  
  2. -- **** Switch to a user database *****  
  3. USE YourDatabaseName;  
  4. GO  
-- Database specific queries ******************************************************
-- **** Switch to a user database *****
USE YourDatabaseName;
GO

查詢數據庫大小：

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  1. -- Individual File Sizes and space available for current database  
  2. SELECT name AS [File Name], physical_name AS [Physical Name], size/128.0 AS [Total  
  3. Size in MB],  
  4. size/128.0 - CAST(FILEPROPERTY(name, 'SpaceUsed') AS int)/128.0 AS [Available Space  
  5. In MB], [file_id]  
  6. FROM sys.database_files WITH (NOLOCK) OPTION (RECOMPILE);  
  7. -- Look at how large and how full the files are and where they are located  
  8. -- Make sure the transaction log is not full!!  
-- Individual File Sizes and space available for current database
SELECT name AS [File Name], physical_name AS [Physical Name], size/128.0 AS [Total
Size in MB],
size/128.0 - CAST(FILEPROPERTY(name, 'SpaceUsed') AS int)/128.0 AS [Available Space
In MB], [file_id]
FROM sys.database_files WITH (NOLOCK) OPTION (RECOMPILE);
-- Look at how large and how full the files are and where they are located
-- Make sure the transaction log is not full!!

查看事務日誌大小及空間使用：

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  1. -- Get transaction log size and space information for the current database  
  2. SELECT DB_NAME(database_id) AS [Database Name], database_id,  
  3. CAST((total_log_size_in_bytes/1048576.0) AS DECIMAL(10,1))  
  4. AS [Total_log_size(MB)],  
  5. CAST((used_log_space_in_bytes/1048576.0) AS DECIMAL(10,1))  
  6. AS [Used_log_space(MB)],  
  7. CAST(used_log_space_in_percent AS DECIMAL(10,1)) AS [Used_log_space(%)]  
  8. FROM sys.dm_db_log_space_usage WITH (NOLOCK) OPTION (RECOMPILE);  
  9. -- Another way to look at transaction log file size and space  
-- Get transaction log size and space information for the current database
SELECT DB_NAME(database_id) AS [Database Name], database_id,
CAST((total_log_size_in_bytes/1048576.0) AS DECIMAL(10,1))
AS [Total_log_size(MB)],
CAST((used_log_space_in_bytes/1048576.0) AS DECIMAL(10,1))
AS [Used_log_space(MB)],
CAST(used_log_space_in_percent AS DECIMAL(10,1)) AS [Used_log_space(%)]
FROM sys.dm_db_log_space_usage WITH (NOLOCK) OPTION (RECOMPILE);
-- Another way to look at transaction log file size and space

按文件蒐集I/O統計：

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  1. -- I/O Statistics by file for the current database  
  2. SELECT DB_NAME(DB_ID()) AS [Database Name],[file_id], num_of_reads, num_of_writes,  
  3. io_stall_read_ms, io_stall_write_ms,  
  4. CAST(100. * io_stall_read_ms/(io_stall_read_ms + io_stall_write_ms)  
  5. AS DECIMAL(10,1)) AS [IO Stall Reads Pct],  
  6. CAST(100. * io_stall_write_ms/(io_stall_write_ms + io_stall_read_ms)  
  7. AS DECIMAL(10,1)) AS [IO Stall Writes Pct],  
  8. (num_of_reads + num_of_writes) AS [Writes + Reads], num_of_bytes_read,  
  9. num_of_bytes_written,  
  10. CAST(100. * num_of_reads/(num_of_reads + num_of_writes) AS DECIMAL(10,1))  
  11. AS [# Reads Pct],  
  12. CAST(100. * num_of_writes/(num_of_reads + num_of_writes) AS DECIMAL(10,1))  
  13. AS [# Write Pct],  
  14. CAST(100. * num_of_bytes_read/(num_of_bytes_read + num_of_bytes_written)  
  15. AS DECIMAL(10,1)) AS [Read Bytes Pct],  
  16. CAST(100. * num_of_bytes_written/(num_of_bytes_read + num_of_bytes_written)  
  17. AS DECIMAL(10,1)) AS [Written Bytes Pct]  
  18. FROM sys.dm_io_virtual_file_stats(DB_ID(), NULL) OPTION (RECOMPILE);  
  19. -- This helps you characterize your workload better from an I/O perspective  
-- I/O Statistics by file for the current database
SELECT DB_NAME(DB_ID()) AS [Database Name],[file_id], num_of_reads, num_of_writes,
io_stall_read_ms, io_stall_write_ms,
CAST(100. * io_stall_read_ms/(io_stall_read_ms + io_stall_write_ms)
AS DECIMAL(10,1)) AS [IO Stall Reads Pct],
CAST(100. * io_stall_write_ms/(io_stall_write_ms + io_stall_read_ms)
AS DECIMAL(10,1)) AS [IO Stall Writes Pct],
(num_of_reads + num_of_writes) AS [Writes + Reads], num_of_bytes_read,
num_of_bytes_written,
CAST(100. * num_of_reads/(num_of_reads + num_of_writes) AS DECIMAL(10,1))
AS [# Reads Pct],
CAST(100. * num_of_writes/(num_of_reads + num_of_writes) AS DECIMAL(10,1))
AS [# Write Pct],
CAST(100. * num_of_bytes_read/(num_of_bytes_read + num_of_bytes_written)
AS DECIMAL(10,1)) AS [Read Bytes Pct],
CAST(100. * num_of_bytes_written/(num_of_bytes_read + num_of_bytes_written)
AS DECIMAL(10,1)) AS [Written Bytes Pct]
FROM sys.dm_io_virtual_file_stats(DB_ID(), NULL) OPTION (RECOMPILE);
-- This helps you characterize your workload better from an I/O perspective

查看事務日誌Virtual Log File (VLF)計數：

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  1. -- Get VLF count for transaction log for the current database,  
  2. -- number of rows equals the VLF count. Lower is better!  
  3. DBCC LOGINFO;  
  4. -- High VLF counts can affect write performance  
  5. -- and they can make database restore and recovery take much longer  
-- Get VLF count for transaction log for the current database,
-- number of rows equals the VLF count. Lower is better!
DBCC LOGINFO;
-- High VLF counts can affect write performance
-- and they can make database restore and recovery take much longer

事務日誌中如果有大量VLF，就會影響寫入事務日誌的性能，更重要的是影響恢復數據庫的時間。
查看特定數據庫上的查詢活動：

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  1. -- Top cached queries by Execution Count (SQL Server 2012)  
  2. SELECT qs.execution_count, qs.total_rows, qs.last_rows, qs.min_rows, qs.max_rows,  
  3. qs.last_elapsed_time, qs.min_elapsed_time, qs.max_elapsed_time,  
  4. SUBSTRING(qt.TEXT,qs.statement_start_offset/2 +1,  
  5. (CASE WHEN qs.statement_end_offset = -1  
  6. THEN LEN(CONVERT(NVARCHAR(MAX), qt.TEXT)) * 2  
  7. ELSE qs.statement_end_offset END - qs.statement_start_offset)/2)  
  8. AS query_text  
  9. FROM sys.dm_exec_query_stats AS qs WITH (NOLOCK)  
  10. CROSS APPLY sys.dm_exec_sql_text(qs.sql_handle) AS qt  
  11. ORDER BY qs.execution_count DESC OPTION (RECOMPILE);  
  12. -- Uses several new rows returned columns  
  13. -- to help troubleshoot performance problems  
-- Top cached queries by Execution Count (SQL Server 2012)
SELECT qs.execution_count, qs.total_rows, qs.last_rows, qs.min_rows, qs.max_rows,
qs.last_elapsed_time, qs.min_elapsed_time, qs.max_elapsed_time,
SUBSTRING(qt.TEXT,qs.statement_start_offset/2 +1,
(CASE WHEN qs.statement_end_offset = -1
THEN LEN(CONVERT(NVARCHAR(MAX), qt.TEXT)) * 2
ELSE qs.statement_end_offset END - qs.statement_start_offset)/2)
AS query_text
FROM sys.dm_exec_query_stats AS qs WITH (NOLOCK)
CROSS APPLY sys.dm_exec_sql_text(qs.sql_handle) AS qt
ORDER BY qs.execution_count DESC OPTION (RECOMPILE);
-- Uses several new rows returned columns
-- to help troubleshoot performance problems

查看緩存的存儲過程：

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  1. -- Top Cached SPs By Execution Count (SQL Server 2012)  
  2. SELECT TOP(250) p.name AS [SP Name], qs.execution_count,  
  3. ISNULL(qs.execution_count/DATEDIFF(Second, qs.cached_time, GETDATE()), 0)  
  4. AS [Calls/Second],  
  5. qs.total_worker_time/qs.execution_count AS [AvgWorkerTime],  
  6. qs.total_worker_time AS [TotalWorkerTime],qs.total_elapsed_time,  
  7. qs.total_elapsed_time/qs.execution_count AS [avg_elapsed_time],  
  8. qs.cached_time  
  9. FROM sys.procedures AS p WITH (NOLOCK)  
  10. INNER JOIN sys.dm_exec_procedure_stats AS qs WITH (NOLOCK)  
  11. ON p.[object_id] = qs.[object_id]  
  12. WHERE qs.database_id = DB_ID()  
  13. ORDER BY qs.execution_count DESC OPTION (RECOMPILE);  
  14. -- Tells you which cached stored procedures are called the most often  
  15. -- This helps you characterize and baseline your workload  
-- Top Cached SPs By Execution Count (SQL Server 2012)
SELECT TOP(250) p.name AS [SP Name], qs.execution_count,
ISNULL(qs.execution_count/DATEDIFF(Second, qs.cached_time, GETDATE()), 0)
AS [Calls/Second],
qs.total_worker_time/qs.execution_count AS [AvgWorkerTime],
qs.total_worker_time AS [TotalWorkerTime],qs.total_elapsed_time,
qs.total_elapsed_time/qs.execution_count AS [avg_elapsed_time],
qs.cached_time
FROM sys.procedures AS p WITH (NOLOCK)
INNER JOIN sys.dm_exec_procedure_stats AS qs WITH (NOLOCK)
ON p.[object_id] = qs.[object_id]
WHERE qs.database_id = DB_ID()
ORDER BY qs.execution_count DESC OPTION (RECOMPILE);
-- Tells you which cached stored procedures are called the most often
-- This helps you characterize and baseline your workload

查看存儲過程在緩存裏待多長時間（Cached_time）：

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  1. -- Top Cached SPs By Avg Elapsed Time (SQL Server 2012)  
  2. SELECT TOP(25) p.name AS [SP Name], qs.total_elapsed_time/qs.execution_count  
  3. AS [avg_elapsed_time], qs.total_elapsed_time, qs.execution_count,  
  4. ISNULL(qs.execution_count/DATEDIFF(Second, qs.cached_time,  
  5. GETDATE()), 0) AS [Calls/Second],  
  6. qs.total_worker_time/qs.execution_count AS [AvgWorkerTime],  
  7. qs.total_worker_time AS [TotalWorkerTime], qs.cached_time  
  8. FROM sys.procedures AS p WITH (NOLOCK)  
  9. INNER JOIN sys.dm_exec_procedure_stats AS qs WITH (NOLOCK)  
  10. ON p.[object_id] = qs.[object_id]  
  11. WHERE qs.database_id = DB_ID()  
  12. ORDER BY avg_elapsed_time DESC OPTION (RECOMPILE);  
  13. -- This helps you find long-running cached stored procedures that  
  14. -- may be easy to optimize with standard query tuning techniques  
-- Top Cached SPs By Avg Elapsed Time (SQL Server 2012)
SELECT TOP(25) p.name AS [SP Name], qs.total_elapsed_time/qs.execution_count
AS [avg_elapsed_time], qs.total_elapsed_time, qs.execution_count,
ISNULL(qs.execution_count/DATEDIFF(Second, qs.cached_time,
GETDATE()), 0) AS [Calls/Second],
qs.total_worker_time/qs.execution_count AS [AvgWorkerTime],
qs.total_worker_time AS [TotalWorkerTime], qs.cached_time
FROM sys.procedures AS p WITH (NOLOCK)
INNER JOIN sys.dm_exec_procedure_stats AS qs WITH (NOLOCK)
ON p.[object_id] = qs.[object_id]
WHERE qs.database_id = DB_ID()
ORDER BY avg_elapsed_time DESC OPTION (RECOMPILE);
-- This helps you find long-running cached stored procedures that
-- may be easy to optimize with standard query tuning techniques

從整體CPU角度查看最耗時的存儲過程：

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  1. -- Top Cached SPs By Total Worker time (SQL Server 2012).  
  2. -- Worker time relates to CPU cost  
  3. SELECT TOP(25) p.name AS [SP Name], qs.total_worker_time AS [TotalWorkerTime],  
  4. qs.total_worker_time/qs.execution_count AS [AvgWorkerTime], qs.execution_count,  
  5. ISNULL(qs.execution_count/DATEDIFF(Second, qs.cached_time, GETDATE()), 0)  
  6. AS [Calls/Second],qs.total_elapsed_time, qs.total_elapsed_time/qs.execution_count  
  7. AS [avg_elapsed_time], qs.cached_time  
  8. FROM sys.procedures AS p WITH (NOLOCK)  
  9. INNER JOIN sys.dm_exec_procedure_stats AS qs WITH (NOLOCK)  
  10. ON p.[object_id] = qs.[object_id]  
  11. WHERE qs.database_id = DB_ID()  
  12. ORDER BY qs.total_worker_time DESC OPTION (RECOMPILE);  
  13. -- This helps you find the most expensive cached  
  14. -- stored procedures from a CPU perspective  
  15. -- You should look at this if you see signs of CPU pressure  
-- Top Cached SPs By Total Worker time (SQL Server 2012).
-- Worker time relates to CPU cost
SELECT TOP(25) p.name AS [SP Name], qs.total_worker_time AS [TotalWorkerTime],
qs.total_worker_time/qs.execution_count AS [AvgWorkerTime], qs.execution_count,
ISNULL(qs.execution_count/DATEDIFF(Second, qs.cached_time, GETDATE()), 0)
AS [Calls/Second],qs.total_elapsed_time, qs.total_elapsed_time/qs.execution_count
AS [avg_elapsed_time], qs.cached_time
FROM sys.procedures AS p WITH (NOLOCK)
INNER JOIN sys.dm_exec_procedure_stats AS qs WITH (NOLOCK)
ON p.[object_id] = qs.[object_id]
WHERE qs.database_id = DB_ID()
ORDER BY qs.total_worker_time DESC OPTION (RECOMPILE);
-- This helps you find the most expensive cached
-- stored procedures from a CPU perspective
-- You should look at this if you see signs of CPU pressure

從邏輯度的角度查看緩存的存儲過程相關的信息：

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  1. -- Top Cached SPs By Total Logical Reads (SQL Server 2012).  
  2. -- Logical reads relate to memory pressure  
  3. SELECT TOP(25) p.name AS [SP Name], qs.total_logical_reads  
  4. AS [TotalLogicalReads], qs.total_logical_reads/qs.execution_count  
  5. AS [AvgLogicalReads],qs.execution_count,  
  6. ISNULL(qs.execution_count/DATEDIFF(Second, qs.cached_time, GETDATE()), 0)  
  7. AS [Calls/Second], qs.total_elapsed_time,qs.total_elapsed_time/qs.execution_count  
  8. AS [avg_elapsed_time], qs.cached_time  
  9. FROM sys.procedures AS p WITH (NOLOCK)  
  10. INNER JOIN sys.dm_exec_procedure_stats AS qs WITH (NOLOCK)  
  11. ON p.[object_id] = qs.[object_id]  
  12. WHERE qs.database_id = DB_ID()  
  13. ORDER BY qs.total_logical_reads DESC OPTION (RECOMPILE);  
  14. -- This helps you find the most expensive cached  
  15. -- stored procedures from a memory perspective  
  16. -- You should look at this if you see signs of memory pressure  
-- Top Cached SPs By Total Logical Reads (SQL Server 2012).
-- Logical reads relate to memory pressure
SELECT TOP(25) p.name AS [SP Name], qs.total_logical_reads
AS [TotalLogicalReads], qs.total_logical_reads/qs.execution_count
AS [AvgLogicalReads],qs.execution_count,
ISNULL(qs.execution_count/DATEDIFF(Second, qs.cached_time, GETDATE()), 0)
AS [Calls/Second], qs.total_elapsed_time,qs.total_elapsed_time/qs.execution_count
AS [avg_elapsed_time], qs.cached_time
FROM sys.procedures AS p WITH (NOLOCK)
INNER JOIN sys.dm_exec_procedure_stats AS qs WITH (NOLOCK)
ON p.[object_id] = qs.[object_id]
WHERE qs.database_id = DB_ID()
ORDER BY qs.total_logical_reads DESC OPTION (RECOMPILE);
-- This helps you find the most expensive cached
-- stored procedures from a memory perspective
-- You should look at this if you see signs of memory pressure

從物理度的角度查看最耗時的存儲過程：

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  1. -- Top Cached SPs By Total Physical Reads (SQL Server 2012).  
  2. -- Physical reads relate to disk I/O pressure  
  3. SELECT TOP(25) p.name AS [SP Name],qs.total_physical_reads  
  4. AS [TotalPhysicalReads],qs.total_physical_reads/qs.execution_count  
  5. AS [AvgPhysicalReads], qs.execution_count, qs.total_logical_reads,  
  6. qs.total_elapsed_time, qs.total_elapsed_time/qs.execution_count  
  7. AS [avg_elapsed_time], qs.cached_time  
  8. FROM sys.procedures AS p WITH (NOLOCK)  
  9. INNER JOIN sys.dm_exec_procedure_stats AS qs WITH (NOLOCK)  
  10. ON p.[object_id] = qs.[object_id]  
  11. WHERE qs.database_id = DB_ID()  
  12. AND qs.total_physical_reads > 0  
  13. ORDER BY qs.total_physical_reads DESC,  
  14. qs.total_logical_reads DESC OPTION (RECOMPILE);  
  15. -- This helps you find the most expensive cached  
  16. -- stored procedures from a read I/O perspective  
  17. -- You should look at this if you see signs of I/O pressure or of memory pressure  
-- Top Cached SPs By Total Physical Reads (SQL Server 2012).
-- Physical reads relate to disk I/O pressure
SELECT TOP(25) p.name AS [SP Name],qs.total_physical_reads
AS [TotalPhysicalReads],qs.total_physical_reads/qs.execution_count
AS [AvgPhysicalReads], qs.execution_count, qs.total_logical_reads,
qs.total_elapsed_time, qs.total_elapsed_time/qs.execution_count
AS [avg_elapsed_time], qs.cached_time
FROM sys.procedures AS p WITH (NOLOCK)
INNER JOIN sys.dm_exec_procedure_stats AS qs WITH (NOLOCK)
ON p.[object_id] = qs.[object_id]
WHERE qs.database_id = DB_ID()
AND qs.total_physical_reads > 0
ORDER BY qs.total_physical_reads DESC,
qs.total_logical_reads DESC OPTION (RECOMPILE);
-- This helps you find the most expensive cached
-- stored procedures from a read I/O perspective
-- You should look at this if you see signs of I/O pressure or of memory pressure

從邏輯寫來看最耗時的緩存存儲過程：

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  1. -- Top Cached SPs By Total Logical Writes (SQL Server 2012).  
  2. -- Logical writes relate to both memory and disk I/O pressure  
  3. SELECT TOP(25) p.name AS [SP Name], qs.total_logical_writes  
  4. AS [TotalLogicalWrites], qs.total_logical_writes/qs.execution_count  
  5. AS [AvgLogicalWrites], qs.execution_count,  
  6. ISNULL(qs.execution_count/DATEDIFF(Second, qs.cached_time, GETDATE()), 0)  
  7. AS [Calls/Second],qs.total_elapsed_time, qs.total_elapsed_time/qs.execution_count  
  8. AS [avg_elapsed_time], qs.cached_time  
  9. FROM sys.procedures AS p WITH (NOLOCK)  
  10. INNER JOIN sys.dm_exec_procedure_stats AS qs WITH (NOLOCK)  
  11. ON p.[object_id] = qs.[object_id]  
  12. WHERE qs.database_id = DB_ID()  
  13. ORDER BY qs.total_logical_writes DESC OPTION (RECOMPILE);  
  14. -- This helps you find the most expensive cached  
  15. -- stored procedures from a write I/O perspective  
  16. -- You should look at this if you see signs of I/O pressure or of memory pressure  
-- Top Cached SPs By Total Logical Writes (SQL Server 2012).
-- Logical writes relate to both memory and disk I/O pressure
SELECT TOP(25) p.name AS [SP Name], qs.total_logical_writes
AS [TotalLogicalWrites], qs.total_logical_writes/qs.execution_count
AS [AvgLogicalWrites], qs.execution_count,
ISNULL(qs.execution_count/DATEDIFF(Second, qs.cached_time, GETDATE()), 0)
AS [Calls/Second],qs.total_elapsed_time, qs.total_elapsed_time/qs.execution_count
AS [avg_elapsed_time], qs.cached_time
FROM sys.procedures AS p WITH (NOLOCK)
INNER JOIN sys.dm_exec_procedure_stats AS qs WITH (NOLOCK)
ON p.[object_id] = qs.[object_id]
WHERE qs.database_id = DB_ID()
ORDER BY qs.total_logical_writes DESC OPTION (RECOMPILE);
-- This helps you find the most expensive cached
-- stored procedures from a write I/O perspective
-- You should look at this if you see signs of I/O pressure or of memory pressure

從平均I/O來看緩存的存儲過程中最耗資源的語句：

[sql] view plain copy
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  1. -- Lists the top statements by average input/output  
  2. -- usage for the current database  
  3. SELECT TOP(50) OBJECT_NAME(qt.objectid) AS [SP Name],  
  4. (qs.total_logical_reads + qs.total_logical_writes) /qs.execution_count  
  5. AS [Avg IO],SUBSTRING(qt.[text],qs.statement_start_offset/2,  
  6. (CASE  
  7. WHEN qs.statement_end_offset = -1  
  8. THEN LEN(CONVERT(nvarchar(max), qt.[text])) * 2  
  9. ELSE qs.statement_end_offset  
  10. END - qs.statement_start_offset)/2) AS [Query Text]  
  11. FROM sys.dm_exec_query_stats AS qs WITH (NOLOCK)  
  12. CROSS APPLY sys.dm_exec_sql_text(qs.sql_handle) AS qt  
  13. WHERE qt.[dbid] = DB_ID()  
  14. ORDER BY [Avg IO] DESC OPTION (RECOMPILE);  
  15. -- Helps you find the most expensive statements for I/O by SP  
-- Lists the top statements by average input/output
-- usage for the current database
SELECT TOP(50) OBJECT_NAME(qt.objectid) AS [SP Name],
(qs.total_logical_reads + qs.total_logical_writes) /qs.execution_count
AS [Avg IO],SUBSTRING(qt.[text],qs.statement_start_offset/2,
(CASE
WHEN qs.statement_end_offset = -1
THEN LEN(CONVERT(nvarchar(max), qt.[text])) * 2
ELSE qs.statement_end_offset
END - qs.statement_start_offset)/2) AS [Query Text]
FROM sys.dm_exec_query_stats AS qs WITH (NOLOCK)
CROSS APPLY sys.dm_exec_sql_text(qs.sql_handle) AS qt
WHERE qt.[dbid] = DB_ID()
ORDER BY [Avg IO] DESC OPTION (RECOMPILE);
-- Helps you find the most expensive statements for I/O by SP

查看寫比讀更多的非聚集索引：

[sql] view plain copy
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  1. -- Possible Bad NC Indexes (writes > reads)  
  2. SELECT OBJECT_NAME(s.[object_id]) AS [Table Name], i.name AS [Index Name],  
  3. i.index_id,user_updates AS [Total Writes],  
  4. user_seeks + user_scans + user_lookups AS [Total Reads],  
  5. user_updates - (user_seeks + user_scans + user_lookups) AS [Difference]  
  6. FROM sys.dm_db_index_usage_stats AS s WITH (NOLOCK)  
  7. INNER JOIN sys.indexes AS i WITH (NOLOCK)  
  8. ON s.[object_id] = i.[object_id]  
  9. AND i.index_id = s.index_id  
  10. WHERE OBJECTPROPERTY(s.[object_id],'IsUserTable') = 1  
  11. AND s.database_id = DB_ID()  
  12. AND user_updates > (user_seeks + user_scans + user_lookups)  
  13. AND i.index_id > 1  
  14. ORDER BY [Difference] DESC, [Total Writes] DESC, [Total Reads] ASC OPTION  
  15. (RECOMPILE);  
  16. -- Look for indexes with high numbers of writes  
  17. -- and zero or very low numbers of reads  
  18. -- Consider your complete workload  
  19. -- Investigate further before dropping an index!  
-- Possible Bad NC Indexes (writes > reads)
SELECT OBJECT_NAME(s.[object_id]) AS [Table Name], i.name AS [Index Name],
i.index_id,user_updates AS [Total Writes],
user_seeks + user_scans + user_lookups AS [Total Reads],
user_updates - (user_seeks + user_scans + user_lookups) AS [Difference]
FROM sys.dm_db_index_usage_stats AS s WITH (NOLOCK)
INNER JOIN sys.indexes AS i WITH (NOLOCK)
ON s.[object_id] = i.[object_id]
AND i.index_id = s.index_id
WHERE OBJECTPROPERTY(s.[object_id],'IsUserTable') = 1
AND s.database_id = DB_ID()
AND user_updates > (user_seeks + user_scans + user_lookups)
AND i.index_id > 1
ORDER BY [Difference] DESC, [Total Writes] DESC, [Total Reads] ASC OPTION
(RECOMPILE);
-- Look for indexes with high numbers of writes
-- and zero or very low numbers of reads
-- Consider your complete workload
-- Investigate further before dropping an index!

查看缺失的索引信息：

[sql] view plain copy
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  1. -- Missing Indexes current database by Index Advantage  
  2. SELECT user_seeks * avg_total_user_cost * (avg_user_impact * 0.01)  
  3. AS [index_advantage],  
  4. migs.last_user_seek, mid.[statement] AS [Database.Schema.Table],  
  5. mid.equality_columns, mid.inequality_columns, mid.included_columns,  
  6. migs.unique_compiles, migs.user_seeks, migs.avg_total_user_cost,  
  7. migs.avg_user_impact  
  8. FROM sys.dm_db_missing_index_group_stats AS migs WITH (NOLOCK)  
  9. INNER JOIN sys.dm_db_missing_index_groups AS mig WITH (NOLOCK)  
  10. ON migs.group_handle = mig.index_group_handle  
  11. INNER JOIN sys.dm_db_missing_index_details AS mid WITH (NOLOCK)  
  12. ON mig.index_handle = mid.index_handle  
  13. WHERE mid.database_id = DB_ID() -- Remove this to see for entire instance  
  14. ORDER BY index_advantage DESC OPTION (RECOMPILE);  
  15. -- Look at last user seek time, number of user seeks  
  16. -- to help determine source and importance  
  17. -- SQL Server is overly eager to add included columns, so beware  
  18. -- Do not just blindly add indexes that show up from this query!!!  
-- Missing Indexes current database by Index Advantage
SELECT user_seeks * avg_total_user_cost * (avg_user_impact * 0.01)
AS [index_advantage],
migs.last_user_seek, mid.[statement] AS [Database.Schema.Table],
mid.equality_columns, mid.inequality_columns, mid.included_columns,
migs.unique_compiles, migs.user_seeks, migs.avg_total_user_cost,
migs.avg_user_impact
FROM sys.dm_db_missing_index_group_stats AS migs WITH (NOLOCK)
INNER JOIN sys.dm_db_missing_index_groups AS mig WITH (NOLOCK)
ON migs.group_handle = mig.index_group_handle
INNER JOIN sys.dm_db_missing_index_details AS mid WITH (NOLOCK)
ON mig.index_handle = mid.index_handle
WHERE mid.database_id = DB_ID() -- Remove this to see for entire instance
ORDER BY index_advantage DESC OPTION (RECOMPILE);
-- Look at last user seek time, number of user seeks
-- to help determine source and importance
-- SQL Server is overly eager to add included columns, so beware
-- Do not just blindly add indexes that show up from this query!!!

查看緩存的執行計劃中缺失索引警告：

[sql] view plain copy
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  1. -- Find missing index warnings for cached plans in the current database  
  2. -- Note: This query could take some time on a busy instance  
  3. SELECT TOP(25) OBJECT_NAME(objectid) AS [ObjectName],query_plan,  
  4. cp.objtype, cp.usecounts  
  5. FROM sys.dm_exec_cached_plans AS cp WITH (NOLOCK)  
  6. CROSS APPLY sys.dm_exec_query_plan(cp.plan_handle) AS qp  
  7. WHERE CAST(query_plan AS NVARCHAR(MAX)) LIKE N'%MissingIndex%'  
  8. AND dbid = DB_ID()  
  9. ORDER BY cp.usecounts DESC OPTION (RECOMPILE);  
  10. -- Helps you connect missing indexes to specific stored procedures or queries  
  11. -- This can help you decide whether to add them or not  
-- Find missing index warnings for cached plans in the current database
-- Note: This query could take some time on a busy instance
SELECT TOP(25) OBJECT_NAME(objectid) AS [ObjectName],query_plan,
cp.objtype, cp.usecounts
FROM sys.dm_exec_cached_plans AS cp WITH (NOLOCK)
CROSS APPLY sys.dm_exec_query_plan(cp.plan_handle) AS qp
WHERE CAST(query_plan AS NVARCHAR(MAX)) LIKE N'%MissingIndex%'
AND dbid = DB_ID()
ORDER BY cp.usecounts DESC OPTION (RECOMPILE);
-- Helps you connect missing indexes to specific stored procedures or queries
-- This can help you decide whether to add them or not

查看SQL Server緩衝池中佔用最多空間的表和索引：

[sql] view plain copy
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  1. -- Breaks down buffers used by current database  
  2. -- by object (table, index) in the buffer cache  
  3. SELECT OBJECT_NAME(p.[object_id]) AS [ObjectName],  
  4. p.index_id, COUNT(*)/128 AS [Buffer size(MB)], COUNT(*) AS [BufferCount],  
  5. p.data_compression_desc AS [CompressionType]  
  6. FROM sys.allocation_units AS a WITH (NOLOCK)  
  7. INNER JOIN sys.dm_os_buffer_descriptors AS b WITH (NOLOCK)  
  8. ON a.allocation_unit_id = b.allocation_unit_id  
  9. INNER JOIN sys.partitions AS p WITH (NOLOCK)  
  10. ON a.container_id = p.hobt_id  
  11. WHERE b.database_id = CONVERT(int,DB_ID())  
  12. AND p.[object_id] > 100  
  13. GROUP BY p.[object_id], p.index_id, p.data_compression_desc  
  14. ORDER BY [BufferCount] DESC OPTION (RECOMPILE);  
  15. -- Tells you what tables and indexes are  
  16. -- using the most memory in the buffer cache  
-- Breaks down buffers used by current database
-- by object (table, index) in the buffer cache
SELECT OBJECT_NAME(p.[object_id]) AS [ObjectName],
p.index_id, COUNT(*)/128 AS [Buffer size(MB)], COUNT(*) AS [BufferCount],
p.data_compression_desc AS [CompressionType]
FROM sys.allocation_units AS a WITH (NOLOCK)
INNER JOIN sys.dm_os_buffer_descriptors AS b WITH (NOLOCK)
ON a.allocation_unit_id = b.allocation_unit_id
INNER JOIN sys.partitions AS p WITH (NOLOCK)
ON a.container_id = p.hobt_id
WHERE b.database_id = CONVERT(int,DB_ID())
AND p.[object_id] > 100
GROUP BY p.[object_id], p.index_id, p.data_compression_desc
ORDER BY [BufferCount] DESC OPTION (RECOMPILE);
-- Tells you what tables and indexes are
-- using the most memory in the buffer cache

查看數據庫中所有表的大小及數據壓縮狀態：

[sql] view plain copy
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  1. -- Get Table names, row counts, and compression status  
  2. -- for the clustered index or heap  
  3. SELECT OBJECT_NAME(object_id) AS [ObjectName],  
  4. SUM(Rows) AS [RowCount], data_compression_desc AS [CompressionType]  
  5. FROM sys.partitions WITH (NOLOCK)  
  6. WHERE index_id < 2 --ignore the partitions from the non-clustered index if any  
  7. AND OBJECT_NAME(object_id) NOT LIKE N'sys%'  
  8. AND OBJECT_NAME(object_id) NOT LIKE N'queue_%'  
  9. AND OBJECT_NAME(object_id) NOT LIKE N'filestream_tombstone%'  
  10. AND OBJECT_NAME(object_id) NOT LIKE N'fulltext%'  
  11. AND OBJECT_NAME(object_id) NOT LIKE N'ifts_comp_fragment%'  
  12. AND OBJECT_NAME(object_id) NOT LIKE N'filetable_updates%'  
  13. GROUP BY object_id, data_compression_desc  
  14. ORDER BY SUM(Rows) DESC OPTION (RECOMPILE);  
  15. -- Gives you an idea of table sizes, and possible data compression opportunities  
-- Get Table names, row counts, and compression status
-- for the clustered index or heap
SELECT OBJECT_NAME(object_id) AS [ObjectName],
SUM(Rows) AS [RowCount], data_compression_desc AS [CompressionType]
FROM sys.partitions WITH (NOLOCK)
WHERE index_id < 2 --ignore the partitions from the non-clustered index if any
AND OBJECT_NAME(object_id) NOT LIKE N'sys%'
AND OBJECT_NAME(object_id) NOT LIKE N'queue_%'
AND OBJECT_NAME(object_id) NOT LIKE N'filestream_tombstone%'
AND OBJECT_NAME(object_id) NOT LIKE N'fulltext%'
AND OBJECT_NAME(object_id) NOT LIKE N'ifts_comp_fragment%'
AND OBJECT_NAME(object_id) NOT LIKE N'filetable_updates%'
GROUP BY object_id, data_compression_desc
ORDER BY SUM(Rows) DESC OPTION (RECOMPILE);
-- Gives you an idea of table sizes, and possible data compression opportunities

查看數據庫中所有索引最後一次統計更新的時間：

[sql] view plain copy
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  1. -- When were Statistics last updated on all indexes?  
  2. SELECT o.name, i.name AS [Index Name],STATS_DATE(i.[object_id],  
  3. i.index_id) AS [Statistics Date], s.auto_created,  
  4. s.no_recompute, s.user_created, st.row_count  
  5. FROM sys.objects AS o WITH (NOLOCK)  
  6. INNER JOIN sys.indexes AS i WITH (NOLOCK)  
  7. ON o.[object_id] = i.[object_id]  
  8. INNER JOIN sys.stats AS s WITH (NOLOCK)  
  9. ON i.[object_id] = s.[object_id]  
  10. AND i.index_id = s.stats_id  
  11. INNER JOIN sys.dm_db_partition_stats AS st WITH (NOLOCK)  
  12. ON o.[object_id] = st.[object_id]  
  13. AND i.[index_id] = st.[index_id]  
  14. WHERE o.[type] = 'U'  
  15. ORDER BY STATS_DATE(i.[object_id], i.index_id) ASC OPTION (RECOMPILE);  
  16. -- Helps discover possible problems with out-of-date statistics  
  17. -- Also gives you an idea which indexes are most active  
-- When were Statistics last updated on all indexes?
SELECT o.name, i.name AS [Index Name],STATS_DATE(i.[object_id],
i.index_id) AS [Statistics Date], s.auto_created,
s.no_recompute, s.user_created, st.row_count
FROM sys.objects AS o WITH (NOLOCK)
INNER JOIN sys.indexes AS i WITH (NOLOCK)
ON o.[object_id] = i.[object_id]
INNER JOIN sys.stats AS s WITH (NOLOCK)
ON i.[object_id] = s.[object_id]
AND i.index_id = s.stats_id
INNER JOIN sys.dm_db_partition_stats AS st WITH (NOLOCK)
ON o.[object_id] = st.[object_id]
AND i.[index_id] = st.[index_id]
WHERE o.[type] = 'U'
ORDER BY STATS_DATE(i.[object_id], i.index_id) ASC OPTION (RECOMPILE);
-- Helps discover possible problems with out-of-date statistics
-- Also gives you an idea which indexes are most active

查看當前數據庫中碎片最多的索引：

[sql] view plain copy
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  1. -- Get fragmentation info for all indexes  
  2. -- above a certain size in the current database  
  3. -- Note: This could take some time on a very large database  
  4. SELECT DB_NAME(database_id) AS [Database Name],  
  5. OBJECT_NAME(ps.OBJECT_ID) AS [Object Name],  
  6. i.name AS [Index Name], ps.index_id, index_type_desc,  
  7. avg_fragmentation_in_percent, fragment_count, page_count  
  8. FROM sys.dm_db_index_physical_stats(DB_ID(),NULL, NULL, NULL ,'LIMITED') AS ps  
  9. INNER JOIN sys.indexes AS i WITH (NOLOCK)  
  10. ON ps.[object_id] = i.[object_id]  
  11. AND ps.index_id = i.index_id  
  12. WHERE database_id = DB_ID()  
  13. AND page_count > 500  
  14. ORDER BY avg_fragmentation_in_percent DESC OPTION (RECOMPILE);  
  15. -- Helps determine whether you have fragmentation in your relational indexes  
  16. -- and how effective your index maintenance strategy is  
-- Get fragmentation info for all indexes
-- above a certain size in the current database
-- Note: This could take some time on a very large database
SELECT DB_NAME(database_id) AS [Database Name],
OBJECT_NAME(ps.OBJECT_ID) AS [Object Name],
i.name AS [Index Name], ps.index_id, index_type_desc,
avg_fragmentation_in_percent, fragment_count, page_count
FROM sys.dm_db_index_physical_stats(DB_ID(),NULL, NULL, NULL ,'LIMITED') AS ps
INNER JOIN sys.indexes AS i WITH (NOLOCK)
ON ps.[object_id] = i.[object_id]
AND ps.index_id = i.index_id
WHERE database_id = DB_ID()
AND page_count > 500
ORDER BY avg_fragmentation_in_percent DESC OPTION (RECOMPILE);
-- Helps determine whether you have fragmentation in your relational indexes
-- and how effective your index maintenance strategy is

如果你發現超過10%碎片的索引，你就需要決定是重組還是重建它們。重組通常是Online操作，能在任何時間停止。重建可以是Online或Offline操作。在SQL Server 2012中，你可以Online重建聚集索引，而不必考慮表包含什麼類型的數據。收縮數據文件非常消耗資源。不要犯常見的錯誤定期去重建所有索引，這非常浪費資源。你可以在Internet上找一些好的索引維護腳本。Ola Hallengren開發了一個非常好的腳本，你可以從 http://ola.hallengren.com獲取。

SQL Server健康檢查的重要性

對一臺新的或不熟悉的服務器，你首先要做的是收集儘可能多有關Server的信息，從硬件和存儲子系統的細節，到OS，再到SQL Server實例本身。你需要知道要處理什麼事情----配置是否差，存儲子系統完全不充分的過時Server，或者，希望一些東西更佳。對於把精力放在正確管理和優化數據庫Server，這份信息是一個關鍵的開始點。作爲一個數據庫專業人士，實在沒有理由不清楚每臺數據庫Server的硬件及配置信息。

這個章節會通過一套查詢帶你做SQL Server健康檢查，解釋其含義及如何理解結果。這些查詢從硬件和實例層次上開始，然後讓你能夠鑽取到一個特定數據庫，去採集更多特定信息。

很多DBA收集這類信息的一個攔路虎是官僚主義。系統管理員或系統工程師提供並管理實際的數據庫Server硬件和OS，SAN管理員常常負責存儲子系統。這些人員中，常有職稱高於你，而對SQL Server基本不懂的人，成爲你收集有關數據庫Server重要信息的一大障礙。他們或許會把信息採集看成是入侵他們的領域，因此不願意配合你。

不管任何官僚主義還是組織障礙，你仍然可以通過技術在SSMS中收集大部分你需要的信息來做比較全面的SQL Server健康檢查。其中最有用、易用的技術是使用DM和DMF來收集服務器、實例及數據庫有關健康檢查的信息。

運行DMV和DMF查詢

要運行大多數的DMV和DMF查詢，你需要對SQL Server實例有VIEW SERVER STATE權限。

首先你要想準確地找出SQL Server的版本、版次及建立，還想知道是x64還是x86、OS是什麼。很簡單，直接可以通過如下非DMV查詢得到：

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  1. SELECT @@VERSION AS [SQL Server and OS Version Info];  
SELECT @@VERSION AS [SQL Server and OS Version Info];

知道這些信息後，有助於瞭解SQL Server的可用功能。例如，企業版有數據壓縮，而標準版或BI版的SQL Server 2012就不能使用數據壓縮。

SQL Server 創建
微軟定期發佈SQL Server的累積更新（CU-Cumulative Update），每個更新有10~40個熱補丁，以集成的安裝包發佈。

下面這個查詢，能夠獲取數據庫Server上有關OS、語言等更多信息：

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  1. SELECT windows_release, windows_service_pack_level,windows_sku, os_language_version FROM sys.dm_os_windows_info WITH (NOLOCK) OPTION (RECOMPILE);  
SELECT windows_release, windows_service_pack_level,windows_sku, os_language_version FROM sys.dm_os_windows_info WITH (NOLOCK) OPTION (RECOMPILE);

下面的查詢會告訴你有多少邏輯處理器、處理器的超線程比率、有多少物力CPU及多大物理內存。

[sql] view plain copy
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  1. -- Hardware information from SQL Server 2012 (new virtual_machine_type_desc)(Cannot distinguish between HT and multi-core)  
  2. SELECT cpu_count AS [Logical CPU Count], hyperthread_ratio AS [HyperthreadRatio],cpu_count/hyperthread_ratio AS [Physical CPU Count],  
  3. physical_memory_kb/1024 AS [Physical Memory (MB)],affinity_type_desc, virtual_machine_type_desc, sqlserver_start_time  
  4. FROM sys.dm_os_sys_info WITH (NOLOCK) OPTION (RECOMPILE);  
  5. -- Gives you some good basic hardware information about your database server  
-- Hardware information from SQL Server 2012 (new virtual_machine_type_desc)(Cannot distinguish between HT and multi-core)
SELECT cpu_count AS [Logical CPU Count], hyperthread_ratio AS [HyperthreadRatio],cpu_count/hyperthread_ratio AS [Physical CPU Count],
physical_memory_kb/1024 AS [Physical Memory (MB)],affinity_type_desc, virtual_machine_type_desc, sqlserver_start_time
FROM sys.dm_os_sys_info WITH (NOLOCK) OPTION (RECOMPILE);
-- Gives you some good basic hardware information about your database server

下面的查詢會讀取SQL Server錯誤日誌，以獲取廠商及數據庫Server的型號（model number）：

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  1. -- Get System Manufacturer and model number from SQL Server Error log. This query might take a few seconds  
  2. -- if you have not recycled your error log recently  
  3. EXEC xp_readerrorlog 0,1,"Manufacturer";  
  4. -- This can help you determine the capabilities and capacities of your database server  
-- Get System Manufacturer and model number from SQL Server Error log. This query might take a few seconds
-- if you have not recycled your error log recently
EXEC xp_readerrorlog 0,1,"Manufacturer";
-- This can help you determine the capabilities and capacities of your database server

知道廠商和型號，你就能找到重要的信息，如有多少處理器插槽、有多少內存插槽，多少及何種類型的PCI-E擴展槽，還會告訴你處理器類型（Intel還是AMD）和處理器是那一代。

下面的查詢會返回處理器的描述及來自Windows Registry的額定時鐘頻率：

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  1. -- Get processor description from Windows Registry  
  2. EXEC xp_instance_regread 'HKEY_LOCAL_MACHINE','HARDWARE\DESCRIPTION\System\CentralProcessor\0','ProcessorNameString';  
  3. -- Gives you the model number and rated clock speed of your processor(s)  
-- Get processor description from Windows Registry
EXEC xp_instance_regread 'HKEY_LOCAL_MACHINE','HARDWARE\DESCRIPTION\System\CentralProcessor\0','ProcessorNameString';
-- Gives you the model number and rated clock speed of your processor(s)

知道額定時鐘頻率非常重要，因爲你的處理器可能因爲電源管理，不是每次都全速運行。Windows Server 2008(R2)使用Balanced Windows Power Plan。這意味着當處理器不在高負荷的情況下，會降低時鐘速率來減少節省電力。當處理器突遇高負載時，它會增加時鐘速率以達到全速，但這不會立即發生從而對查詢性能有負面影響。當使用默認的Balanced Windows Power Plan，而不是High Performance電源計劃，通常OLTP負載下只有20~25%的速率。要避免這樣的問題，你首先要確認你的數據庫Server使用High Performance電源計劃，而不是Balanced電源計劃。這個設置可以動態改變，不需要重啓Windows。其次，使用cpuid.com提供的CPU-Z免費工具確定實際的時鐘速率。如果你使用高性能電源計劃且處理器仍然美歐全速運行，那麼你需要進入系統BIOS去改變電源管理設置，要麼OS控制，要麼完全禁用。

下面的查詢會返回安裝哪些SQL Server服務及其如何配置的信息：

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  1. -- SQL Server Services information from SQL Server 2012  
  2. SELECT servicename, startup_type_desc, status_desc,last_startup_time, service_account, is_clustered, cluster_nodename  
  3. FROM sys.dm_server_services WITH (NOLOCK) OPTION (RECOMPILE);  
  4. -- Gives you information about your installed SQL Server Services, whether they are clustered, and which node owns the cluster resources  
-- SQL Server Services information from SQL Server 2012
SELECT servicename, startup_type_desc, status_desc,last_startup_time, service_account, is_clustered, cluster_nodename
FROM sys.dm_server_services WITH (NOLOCK) OPTION (RECOMPILE);
-- Gives you information about your installed SQL Server Services, whether they are clustered, and which node owns the cluster resources

下面的查詢獲取SQL Server錯誤日誌相關的信息，事先知道錯誤日誌的路徑等有助於在必要時去查閱：

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  1. -- Shows you where the SQL Server error log is located and how it is configured  
  2. SELECT is_enabled, [path], max_size, max_files  
  3. FROM sys.dm_os_server_diagnostics_log_configurations WITH (NOLOCK) OPTION (RECOMPILE);  
  4. -- Knowing this information is important for troubleshooting purposes  
-- Shows you where the SQL Server error log is located and how it is configured
SELECT is_enabled, [path], max_size, max_files
FROM sys.dm_os_server_diagnostics_log_configurations WITH (NOLOCK) OPTION (RECOMPILE);
-- Knowing this information is important for troubleshooting purposes

下面的查詢會返回是否你的數據庫Server使用了Windows Clustering：

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  1. -- Get information about your OS cluster  
  2. --(if your database server is in a cluster)  
  3. SELECT VerboseLogging, SqlDumperDumpFlags, SqlDumperDumpPath,SqlDumperDumpTimeOut, FailureConditionLevel, HealthCheckTimeout  
  4. FROM sys.dm_os_cluster_properties WITH (NOLOCK) OPTION (RECOMPILE);  
  5. -- You will see no results if your instance is not clustered  
-- Get information about your OS cluster
--(if your database server is in a cluster)
SELECT VerboseLogging, SqlDumperDumpFlags, SqlDumperDumpPath,SqlDumperDumpTimeOut, FailureConditionLevel, HealthCheckTimeout
FROM sys.dm_os_cluster_properties WITH (NOLOCK) OPTION (RECOMPILE);
-- You will see no results if your instance is not clustered

如果你使用羣集，你可以使用下面的查詢來獲取有關羣集節點的有用信息：

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  1. -- Get information about your cluster nodes and their status (if your database server is in a cluster)  
  2. SELECT NodeName, status_description, is_current_owner  
  3. FROM sys.dm_os_cluster_nodes WITH (NOLOCK) OPTION (RECOMPILE);  
  4. -- Knowing which node owns the cluster resources is critical Especially when you are installing Windows or SQL Server updates  
-- Get information about your cluster nodes and their status (if your database server is in a cluster)
SELECT NodeName, status_description, is_current_owner
FROM sys.dm_os_cluster_nodes WITH (NOLOCK) OPTION (RECOMPILE);
-- Knowing which node owns the cluster resources is critical Especially when you are installing Windows or SQL Server updates

下面的查詢收集有關SQL Server實例配置的額外信息，你可以使用sp_configure來改變屬性：

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  1. -- Get configuration values for instance  
  2. SELECT name, value, value_in_use, [description] FROM sys.configurations WITH (NOLOCK) ORDER BY name OPTION (RECOMPILE);  
  3. -- Focus on backup compression default  
  4. -- clr enabled (only enable if it is needed)  
  5. -- lightweight pooling (should be zero)  
  6. -- max degree of parallelism  
  7. -- max server memory (MB) (set to an appropriate value)  
  8. -- optimize for ad hoc workloads (should be 1)  
  9. -- priority boost (should be zero)  
-- Get configuration values for instance
SELECT name, value, value_in_use, [description] FROM sys.configurations WITH (NOLOCK) ORDER BY name OPTION (RECOMPILE);
-- Focus on backup compression default
-- clr enabled (only enable if it is needed)
-- lightweight pooling (should be zero)
-- max degree of parallelism
-- max server memory (MB) (set to an appropriate value)
-- optimize for ad hoc workloads (should be 1)
-- priority boost (should be zero)

下面的查詢返回網絡配置相關的一點信息，對於處理網絡、防火牆相關的問題有幫助：

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  1. -- Get information about TCP Listener for SQL Server  
  2. SELECT listener_id, ip_address, is_ipv4, port, type_desc, state_desc, start_time  
  3. FROM sys.dm_tcp_listener_states WITH (NOLOCK) OPTION (RECOMPILE);  
  4. -- Helpful for network and connectivity troubleshooting  
-- Get information about TCP Listener for SQL Server
SELECT listener_id, ip_address, is_ipv4, port, type_desc, state_desc, start_time
FROM sys.dm_tcp_listener_states WITH (NOLOCK) OPTION (RECOMPILE);
-- Helpful for network and connectivity troubleshooting

下面的查詢返回來自Windows註冊表SQL Server相關的信息：

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  1. -- SQL Server Registry information  
  2. SELECT registry_key, value_name, value_data  
  3. FROM sys.dm_server_registry WITH (NOLOCK) OPTION (RECOMPILE);  
  4. -- This lets you safely read some SQL Server related information from the Windows Registry  
-- SQL Server Registry information
SELECT registry_key, value_name, value_data
FROM sys.dm_server_registry WITH (NOLOCK) OPTION (RECOMPILE);
-- This lets you safely read some SQL Server related information from the Windows Registry

下面的查詢返回是否SQL Server實例產生內存轉儲：

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  1. -- Get information on location, time and size of any memory dumps from SQL Server  
  2. SELECT [filename], creation_time, size_in_bytes  
  3. FROM sys.dm_server_memory_dumps WITH (NOLOCK) OPTION (RECOMPILE);  
  4. -- This will not return any rows if you have not had any memory dumps (which is a good thing)  
-- Get information on location, time and size of any memory dumps from SQL Server
SELECT [filename], creation_time, size_in_bytes
FROM sys.dm_server_memory_dumps WITH (NOLOCK) OPTION (RECOMPILE);
-- This will not return any rows if you have not had any memory dumps (which is a good thing)

下面的查詢返回SQL Server實例有多少在運行的數據庫，它們位於哪裏：

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  1. -- File Names and Paths for Tempdb and all user databases in instance  
  2. SELECT DB_NAME([database_id])AS [Database Name],  
  3. [file_id], name, physical_name, type_desc, state_desc,  
  4. CONVERT( bigint, size/128.0) AS [Total Size in MB]  
  5. FROM sys.master_files WITH (NOLOCK)  
  6. WHERE [database_id] > 4  
  7. AND [database_id] <> 32767  
  8. OR [database_id] = 2  
  9. ORDER BY DB_NAME([database_id]) OPTION (RECOMPILE);  
  10. -- Things to look at:  
  11. -- Are data files and log files on different drives?  
  12. -- Is everything on the C: drive?  
  13. -- Is TempDB on dedicated drives?  
  14. -- Are there multiple data files?  
-- File Names and Paths for Tempdb and all user databases in instance
SELECT DB_NAME([database_id])AS [Database Name],
[file_id], name, physical_name, type_desc, state_desc,
CONVERT( bigint, size/128.0) AS [Total Size in MB]
FROM sys.master_files WITH (NOLOCK)
WHERE [database_id] > 4
AND [database_id] <> 32767
OR [database_id] = 2
ORDER BY DB_NAME([database_id]) OPTION (RECOMPILE);
-- Things to look at:
-- Are data files and log files on different drives?
-- Is everything on the C: drive?
-- Is TempDB on dedicated drives?
-- Are there multiple data files?

下面的查詢返回實例上所有數據庫的一些關鍵屬性：

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  1. -- Recovery model, log reuse wait description, log file size, log usage size  
  2. -- and compatibility level for all databases on instance  
  3. SELECT db.[name] AS [Database Name], db.recovery_model_desc AS [Recovery Model],  
  4. db.log_reuse_wait_desc AS [Log Reuse Wait Description],  
  5. ls.cntr_value AS [Log Size (KB)], lu.cntr_value AS [Log Used (KB)],  
  6. CAST(CAST(lu.cntr_value AS FLOAT) / CAST(ls.cntr_value AS FLOAT)AS DECIMAL(18,2)) *  
  7. 100 AS  
  8. [Log Used %], db.[compatibility_level] AS [DB Compatibility Level],  
  9. db.page_verify_option_desc AS [Page Verify Option], db.is_auto_create_stats_on,  
  10. db.is_auto_update_stats_on, db.is_auto_update_stats_async_on,  
  11. db.is_parameterization_forced,  
  12. db.snapshot_isolation_state_desc, db.is_read_committed_snapshot_on,  
  13. is_auto_shrink_on, is_auto_close_on  
  14. FROM sys.databases AS db WITH (NOLOCK)  
  15. INNER JOIN sys.dm_os_performance_counters AS lu WITH (NOLOCK)  
  16. ON db.name = lu.instance_name  
  17. INNER JOIN sys.dm_os_performance_counters AS ls WITH (NOLOCK)  
  18. ON db.name = ls.instance_name  
  19. WHERE lu.counter_name LIKE N'Log File(s) Used Size (KB)%'  
  20. AND ls.counter_name LIKE N'Log File(s) Size (KB)%'  
  21. AND ls.cntr_value > 0 OPTION (RECOMPILE);  
  22. -- Things to look at:  
  23. -- How many databases are on the instance?  
  24. -- What recovery models are they using?  
  25. -- What is the log reuse wait description?  
  26. -- How full are the transaction logs ?  
  27. -- What compatibility level are they on?  
-- Recovery model, log reuse wait description, log file size, log usage size
-- and compatibility level for all databases on instance
SELECT db.[name] AS [Database Name], db.recovery_model_desc AS [Recovery Model],
db.log_reuse_wait_desc AS [Log Reuse Wait Description],
ls.cntr_value AS [Log Size (KB)], lu.cntr_value AS [Log Used (KB)],
CAST(CAST(lu.cntr_value AS FLOAT) / CAST(ls.cntr_value AS FLOAT)AS DECIMAL(18,2)) *
100 AS
[Log Used %], db.[compatibility_level] AS [DB Compatibility Level],
db.page_verify_option_desc AS [Page Verify Option], db.is_auto_create_stats_on,
db.is_auto_update_stats_on, db.is_auto_update_stats_async_on,
db.is_parameterization_forced,
db.snapshot_isolation_state_desc, db.is_read_committed_snapshot_on,
is_auto_shrink_on, is_auto_close_on
FROM sys.databases AS db WITH (NOLOCK)
INNER JOIN sys.dm_os_performance_counters AS lu WITH (NOLOCK)
ON db.name = lu.instance_name
INNER JOIN sys.dm_os_performance_counters AS ls WITH (NOLOCK)
ON db.name = ls.instance_name
WHERE lu.counter_name LIKE N'Log File(s) Used Size (KB)%'
AND ls.counter_name LIKE N'Log File(s) Size (KB)%'
AND ls.cntr_value > 0 OPTION (RECOMPILE);
-- Things to look at:
-- How many databases are on the instance?
-- What recovery models are they using?
-- What is the log reuse wait description?
-- How full are the transaction logs ?
-- What compatibility level are they on?

下面的查詢返回哪個數據庫文件有最大的I/O延遲：

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  1. -- Calculates average stalls per read, per write,  
  2. -- and per total input/output for each database file.  
  3. SELECT DB_NAME(fs.database_id) AS [Database Name], mf.physical_name,  
  4. io_stall_read_ms, num_of_reads,  
  5. CAST(io_stall_read_ms/(1.0 + num_of_reads) AS NUMERIC(10,1)) AS  
  6. [avg_read_stall_ms],io_stall_write_ms,  
  7. num_of_writes,CAST(io_stall_write_ms/(1.0+num_of_writes) AS NUMERIC(10,1)) AS  
  8. [avg_write_stall_ms],  
  9. io_stall_read_ms + io_stall_write_ms AS [io_stalls], num_of_reads + num_of_writes  
  10. AS [total_io],  
  11. CAST((io_stall_read_ms + io_stall_write_ms)/(1.0 + num_of_reads + num_of_writes) AS  
  12. NUMERIC(10,1))  
  13. AS [avg_io_stall_ms]  
  14. FROM sys.dm_io_virtual_file_stats(null,null) AS fs  
  15. INNER JOIN sys.master_files AS mf WITH (NOLOCK)  
  16. ON fs.database_id = mf.database_id  
  17. AND fs.[file_id] = mf.[file_id]  
  18. ORDER BY avg_io_stall_ms DESC OPTION (RECOMPILE);  
  19. -- Helps determine which database files on  
  20. -- the entire instance have the most I/O bottlenecks  
-- Calculates average stalls per read, per write,
-- and per total input/output for each database file.
SELECT DB_NAME(fs.database_id) AS [Database Name], mf.physical_name,
io_stall_read_ms, num_of_reads,
CAST(io_stall_read_ms/(1.0 + num_of_reads) AS NUMERIC(10,1)) AS
[avg_read_stall_ms],io_stall_write_ms,
num_of_writes,CAST(io_stall_write_ms/(1.0+num_of_writes) AS NUMERIC(10,1)) AS
[avg_write_stall_ms],
io_stall_read_ms + io_stall_write_ms AS [io_stalls], num_of_reads + num_of_writes
AS [total_io],
CAST((io_stall_read_ms + io_stall_write_ms)/(1.0 + num_of_reads + num_of_writes) AS
NUMERIC(10,1))
AS [avg_io_stall_ms]
FROM sys.dm_io_virtual_file_stats(null,null) AS fs
INNER JOIN sys.master_files AS mf WITH (NOLOCK)
ON fs.database_id = mf.database_id
AND fs.[file_id] = mf.[file_id]
ORDER BY avg_io_stall_ms DESC OPTION (RECOMPILE);
-- Helps determine which database files on
-- the entire instance have the most I/O bottlenecks

如果遇到I/O瓶頸，你可以使用Windows Performance Monitor查看邏輯磁盤的Avg Disk Sec/Write和 Avg Disk Sec/Read等計數器。根據存儲的類型，通過增加更多的spindle、改變RAID控制器高速緩存策略或改變RAID級別或許可以改善I/O性能。如果可能的話，你也可以考慮移除一些數據文件到其他磁盤。

下面的查詢返回佔用最多內存的用戶數據庫：

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  1. -- Get total buffer usage by database for current instance  
  2. SELECT DB_NAME(database_id) AS [Database Name],  
  3. COUNT(*) * 8/1024.0 AS [Cached Size (MB)]  
  4. FROM sys.dm_os_buffer_descriptors WITH (NOLOCK)  
  5. WHERE database_id > 4 -- system databases  
  6. AND database_id <> 32767 -- ResourceDB  
  7. GROUP BY DB_NAME(database_id)  
  8. ORDER BY [Cached Size (MB)] DESC OPTION (RECOMPILE);  
  9. -- Tells you how much memory (in the buffer pool)  
  10. -- is being used by each database on the instance  
-- Get total buffer usage by database for current instance
SELECT DB_NAME(database_id) AS [Database Name],
COUNT(*) * 8/1024.0 AS [Cached Size (MB)]
FROM sys.dm_os_buffer_descriptors WITH (NOLOCK)
WHERE database_id > 4 -- system databases
AND database_id <> 32767 -- ResourceDB
GROUP BY DB_NAME(database_id)
ORDER BY [Cached Size (MB)] DESC OPTION (RECOMPILE);
-- Tells you how much memory (in the buffer pool)
-- is being used by each database on the instance

下面的查詢返回使用最多處理器時間的用戶數據庫：

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  1. -- Get CPU utilization by database  
  2. WITH DB_CPU_Stats  
  3. AS  
  4. (SELECT DatabaseID, DB_Name(DatabaseID) AS [DatabaseName],  
  5. SUM(total_worker_time) AS [CPU_Time_Ms]  
  6. FROM sys.dm_exec_query_stats AS qs  
  7. CROSS APPLY (SELECT CONVERT(int, value) AS [DatabaseID]  
  8. FROM sys.dm_exec_plan_attributes(qs.plan_handle)  
  9. WHERE attribute = N'dbid') AS F_DB  
  10. GROUP BY DatabaseID)  
  11. SELECT ROW_NUMBER() OVER(ORDER BY [CPU_Time_Ms] DESC) AS [row_num],  
  12. DatabaseName, [CPU_Time_Ms],  
  13. CAST([CPU_Time_Ms] * 1.0 / SUM([CPU_Time_Ms])  
  14. OVER() * 100.0 AS DECIMAL(5, 2)) AS [CPUPercent]  
  15. FROM DB_CPU_Stats  
  16. WHERE DatabaseID > 4 -- system databases  
  17. AND DatabaseID <> 32767 -- ResourceDB  
  18. ORDER BY row_num OPTION (RECOMPILE);  
  19. -- Helps determine which database is using the most CPU resources on the instance  
-- Get CPU utilization by database
WITH DB_CPU_Stats
AS
(SELECT DatabaseID, DB_Name(DatabaseID) AS [DatabaseName],
SUM(total_worker_time) AS [CPU_Time_Ms]
FROM sys.dm_exec_query_stats AS qs
CROSS APPLY (SELECT CONVERT(int, value) AS [DatabaseID]
FROM sys.dm_exec_plan_attributes(qs.plan_handle)
WHERE attribute = N'dbid') AS F_DB
GROUP BY DatabaseID)
SELECT ROW_NUMBER() OVER(ORDER BY [CPU_Time_Ms] DESC) AS [row_num],
DatabaseName, [CPU_Time_Ms],
CAST([CPU_Time_Ms] * 1.0 / SUM([CPU_Time_Ms])
OVER() * 100.0 AS DECIMAL(5, 2)) AS [CPUPercent]
FROM DB_CPU_Stats
WHERE DatabaseID > 4 -- system databases
AND DatabaseID <> 32767 -- ResourceDB
ORDER BY row_num OPTION (RECOMPILE);
-- Helps determine which database is using the most CPU resources on the instance

下面的查詢返回SQL Server上次重啓或使用DBCC SQLPERF ('sys.dm_os_wait_stats', CLEAR)以來，最高的累計等待統計：

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  1. -- Isolate top waits for server instance since last restart or statistics clear  
  2. WITH Waits AS  
  3. (SELECT wait_type, wait_time_ms / 1000. AS wait_time_s,  
  4. 100. * wait_time_ms / SUM(wait_time_ms) OVER() AS pct,  
  5. ROW_NUMBER() OVER(ORDER BY wait_time_ms DESC) AS rn  
  6. FROM sys.dm_os_wait_stats WITH (NOLOCK)  
  7. WHERE wait_type NOT IN (N'CLR_SEMAPHORE',N'LAZYWRITER_SLEEP',N'RESOURCE_QUEUE',  
  8. N'SLEEP_TASK',N'SLEEP_SYSTEMTASK',N'SQLTRACE_BUFFER_FLUSH',N'WAITFOR',  
  9. N'LOGMGR_QUEUE',N'CHECKPOINT_QUEUE', N'REQUEST_FOR_DEADLOCK_SEARCH',  
  10. N'XE_TIMER_EVENT',N'BROKER_TO_FLUSH',N'BROKER_TASK_STOP',N'CLR_MANUAL_EVENT',  
  11. N'CLR_AUTO_EVENT',N'DISPATCHER_QUEUE_SEMAPHORE', N'FT_IFTS_SCHEDULER_IDLE_WAIT',  
  12. N'XE_DISPATCHER_WAIT', N'XE_DISPATCHER_JOIN', N'SQLTRACE_INCREMENTAL_FLUSH_SLEEP',  
  13. N'ONDEMAND_TASK_QUEUE', N'BROKER_EVENTHANDLER', N'SLEEP_BPOOL_FLUSH',  
  14. N'DIRTY_PAGE_POLL', N'HADR_FILESTREAM_IOMGR_IOCOMPLETION',  
  15. N'SP_SERVER_DIAGNOSTICS_SLEEP'))  
  16. SELECT W1.wait_type,  
  17. CAST(W1.wait_time_s AS DECIMAL(12, 2)) AS wait_time_s,  
  18. CAST(W1.pct AS DECIMAL(12, 2)) AS pct,  
  19. CAST(SUM(W2.pct) AS DECIMAL(12, 2)) AS running_pct  
  20. FROM Waits AS W1  
  21. INNER JOIN Waits AS W2  
  22. ON W2.rn <= W1.rn  
  23. GROUP BY W1.rn, W1.wait_type, W1.wait_time_s, W1.pct  
  24. HAVING SUM(W2.pct) - W1.pct < 99 OPTION (RECOMPILE); -- percentage threshold  
  25. -- Clear Wait Stats  
  26. -- DBCC SQLPERF('sys.dm_os_wait_stats', CLEAR);  
-- Isolate top waits for server instance since last restart or statistics clear
WITH Waits AS
(SELECT wait_type, wait_time_ms / 1000. AS wait_time_s,
100. * wait_time_ms / SUM(wait_time_ms) OVER() AS pct,
ROW_NUMBER() OVER(ORDER BY wait_time_ms DESC) AS rn
FROM sys.dm_os_wait_stats WITH (NOLOCK)
WHERE wait_type NOT IN (N'CLR_SEMAPHORE',N'LAZYWRITER_SLEEP',N'RESOURCE_QUEUE',
N'SLEEP_TASK',N'SLEEP_SYSTEMTASK',N'SQLTRACE_BUFFER_FLUSH',N'WAITFOR',
N'LOGMGR_QUEUE',N'CHECKPOINT_QUEUE', N'REQUEST_FOR_DEADLOCK_SEARCH',
N'XE_TIMER_EVENT',N'BROKER_TO_FLUSH',N'BROKER_TASK_STOP',N'CLR_MANUAL_EVENT',
N'CLR_AUTO_EVENT',N'DISPATCHER_QUEUE_SEMAPHORE', N'FT_IFTS_SCHEDULER_IDLE_WAIT',
N'XE_DISPATCHER_WAIT', N'XE_DISPATCHER_JOIN', N'SQLTRACE_INCREMENTAL_FLUSH_SLEEP',
N'ONDEMAND_TASK_QUEUE', N'BROKER_EVENTHANDLER', N'SLEEP_BPOOL_FLUSH',
N'DIRTY_PAGE_POLL', N'HADR_FILESTREAM_IOMGR_IOCOMPLETION',
N'SP_SERVER_DIAGNOSTICS_SLEEP'))
SELECT W1.wait_type,
CAST(W1.wait_time_s AS DECIMAL(12, 2)) AS wait_time_s,
CAST(W1.pct AS DECIMAL(12, 2)) AS pct,
CAST(SUM(W2.pct) AS DECIMAL(12, 2)) AS running_pct
FROM Waits AS W1
INNER JOIN Waits AS W2
ON W2.rn <= W1.rn
GROUP BY W1.rn, W1.wait_type, W1.wait_time_s, W1.pct
HAVING SUM(W2.pct) - W1.pct < 99 OPTION (RECOMPILE); -- percentage threshold
-- Clear Wait Stats
-- DBCC SQLPERF('sys.dm_os_wait_stats', CLEAR);

博客http://blogs.msdn.com/b/psssql/archive/2009/11/03/the-sql-server-wait-type-repository.aspx裏介紹了很多等待類型。

下面的查詢返回實例上累積的信號（CPU）等待：

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  1. -- Signal Waits for instance  
  2. SELECT CAST(100.0 * SUM(signal_wait_time_ms) / SUM (wait_time_ms) AS NUMERIC(20,2))  
  3. AS [%signal (cpu) waits],  
  4. CAST(100.0 * SUM(wait_time_ms - signal_wait_time_ms) / SUM (wait_time_ms) AS  
  5. NUMERIC(20,2)) AS [%resource waits]  
  6. FROM sys.dm_os_wait_stats WITH (NOLOCK) OPTION (RECOMPILE);  
  7. -- Signal Waits above 15-20% is usually a sign of CPU pressure  
-- Signal Waits for instance
SELECT CAST(100.0 * SUM(signal_wait_time_ms) / SUM (wait_time_ms) AS NUMERIC(20,2))
AS [%signal (cpu) waits],
CAST(100.0 * SUM(wait_time_ms - signal_wait_time_ms) / SUM (wait_time_ms) AS
NUMERIC(20,2)) AS [%resource waits]
FROM sys.dm_os_wait_stats WITH (NOLOCK) OPTION (RECOMPILE);
-- Signal Waits above 15-20% is usually a sign of CPU pressure

信號等待是CPU相關的等待。通常信號等待在15~20%就表示CPU壓力。

下面的查詢返回最常連接數據庫的登錄信息：

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  1. -- Get logins that are connected and how many sessions they have  
  2. SELECT login_name, COUNT(session_id) AS [session_count]  
  3. FROM sys.dm_exec_sessions WITH (NOLOCK)  
  4. GROUP BY login_name  
  5. ORDER BY COUNT(session_id) DESC OPTION (RECOMPILE);  
  6. -- This can help characterize your workload and  
  7. -- determine whether you are seeing a normal level of activity  
-- Get logins that are connected and how many sessions they have
SELECT login_name, COUNT(session_id) AS [session_count]
FROM sys.dm_exec_sessions WITH (NOLOCK)
GROUP BY login_name
ORDER BY COUNT(session_id) DESC OPTION (RECOMPILE);
-- This can help characterize your workload and
-- determine whether you are seeing a normal level of activity

下面的查詢返回當前的任務急pending的I/O計數信息，返回的3個值越低越好：

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  1. -- Get Average Task Counts (run multiple times)  
  2. SELECT AVG(current_tasks_count) AS [Avg Task Count],  
  3. AVG(runnable_tasks_count) AS [Avg Runnable Task Count],  
  4. AVG(pending_disk_io_count) AS [Avg Pending DiskIO Count]  
  5. FROM sys.dm_os_schedulers WITH (NOLOCK)  
  6. WHERE scheduler_id < 255 OPTION (RECOMPILE);  
  7. -- Sustained values above 10 suggest further investigation in that area  
  8. -- High Avg Task Counts are often caused by blocking or other resource contention  
  9. -- High Avg Runnable Task Counts are a good sign of CPU pressure  
  10. -- High Avg Pending DiskIO Counts are a sign of disk pressure  
-- Get Average Task Counts (run multiple times)
SELECT AVG(current_tasks_count) AS [Avg Task Count],
AVG(runnable_tasks_count) AS [Avg Runnable Task Count],
AVG(pending_disk_io_count) AS [Avg Pending DiskIO Count]
FROM sys.dm_os_schedulers WITH (NOLOCK)
WHERE scheduler_id < 255 OPTION (RECOMPILE);
-- Sustained values above 10 suggest further investigation in that area
-- High Avg Task Counts are often caused by blocking or other resource contention
-- High Avg Runnable Task Counts are a good sign of CPU pressure
-- High Avg Pending DiskIO Counts are a sign of disk pressure

下面的查詢返回過去256分鐘CPU使用的歷史狀況，1分鐘一個間隔：

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  1. -- Get CPU Utilization History for last 256 minutes (in one minute intervals)  
  2. -- This version works with SQL Server 2008 and above  
  3. DECLARE @ts_now bigint = (SELECT cpu_ticks/(cpu_ticks/ms_ticks)  
  4. FROM sys.dm_os_sys_info WITH (NOLOCK));  
  5. SELECT TOP(256) SQLProcessUtilization AS [SQL Server Process CPU Utilization],  
  6. SystemIdle AS [System Idle Process],  
  7. 100 - SystemIdle - SQLProcessUtilization  
  8. AS [Other Process CPU Utilization],  
  9. DATEADD(ms, -1 * (@ts_now - [timestamp]),  
  10. GETDATE()) AS [Event Time]  
  11. FROM (SELECT record.value('(./Record/@id)[1]', 'int') AS record_id,  
  12. record.value('(./Record/SchedulerMonitorEvent/SystemHealth/SystemIdle)[1]', 'int')  
  13. AS[SystemIdle],record.value('(./Record/SchedulerMonitorEvent/SystemHealth/  
  14. ProcessUtilization)[1]','int')  
  15. AS [SQLProcessUtilization], [timestamp]  
  16. FROM (SELECT [timestamp], CONVERT(xml, record) AS [record]  
  17. FROM sys.dm_os_ring_buffers WITH (NOLOCK)  
  18. WHERE ring_buffer_type = N'RING_BUFFER_SCHEDULER_MONITOR'  
  19. AND record LIKE N'%<SystemHealth>%') AS x  
  20. ) AS y  
  21. ORDER BY record_id DESC OPTION (RECOMPILE);  
  22. -- Look at the trend over the entire period.  
  23. -- Also look at high sustained Other Process CPU Utilization values  
-- Get CPU Utilization History for last 256 minutes (in one minute intervals)
-- This version works with SQL Server 2008 and above
DECLARE @ts_now bigint = (SELECT cpu_ticks/(cpu_ticks/ms_ticks)
FROM sys.dm_os_sys_info WITH (NOLOCK));
SELECT TOP(256) SQLProcessUtilization AS [SQL Server Process CPU Utilization],
SystemIdle AS [System Idle Process],
100 - SystemIdle - SQLProcessUtilization
AS [Other Process CPU Utilization],
DATEADD(ms, -1 * (@ts_now - [timestamp]),
GETDATE()) AS [Event Time]
FROM (SELECT record.value('(./Record/@id)[1]', 'int') AS record_id,
record.value('(./Record/SchedulerMonitorEvent/SystemHealth/SystemIdle)[1]', 'int')
AS[SystemIdle],record.value('(./Record/SchedulerMonitorEvent/SystemHealth/
ProcessUtilization)[1]','int')
AS [SQLProcessUtilization], [timestamp]
FROM (SELECT [timestamp], CONVERT(xml, record) AS [record]
FROM sys.dm_os_ring_buffers WITH (NOLOCK)
WHERE ring_buffer_type = N'RING_BUFFER_SCHEDULER_MONITOR'
AND record LIKE N'%<SystemHealth>%') AS x
) AS y
ORDER BY record_id DESC OPTION (RECOMPILE);
-- Look at the trend over the entire period.
-- Also look at high sustained Other Process CPU Utilization values

如果Other Process CPU Utilization持續超過5%，你就應該查看什麼在使用CPU。

下面的查詢返回OS級別物理內存的狀況：

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  1. -- Good basic information about OS memory amounts and state  
  2. SELECT total_physical_memory_kb, available_physical_memory_kb,  
  3. total_page_file_kb, available_page_file_kb,  
  4. system_memory_state_desc  
  5. FROM sys.dm_os_sys_memory WITH (NOLOCK) OPTION (RECOMPILE);  
  6. -- You want to see "Available physical memory is high"  
  7. -- This indicates that you are not under external memory pressure  
-- Good basic information about OS memory amounts and state
SELECT total_physical_memory_kb, available_physical_memory_kb,
total_page_file_kb, available_page_file_kb,
system_memory_state_desc
FROM sys.dm_os_sys_memory WITH (NOLOCK) OPTION (RECOMPILE);
-- You want to see "Available physical memory is high"
-- This indicates that you are not under external memory pressure

下面的查詢返回SQL Server的內存使用情況：

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  1. -- SQL Server Process Address space info  
  2. --(shows whether locked pages is enabled, among other things)  
  3. SELECT physical_memory_in_use_kb,locked_page_allocations_kb,  
  4. page_fault_count, memory_utilization_percentage,  
  5. available_commit_limit_kb, process_physical_memory_low,  
  6. process_virtual_memory_low  
  7. FROM sys.dm_os_process_memory WITH (NOLOCK) OPTION (RECOMPILE);  
  8. -- You want to see 0 for process_physical_memory_low  
  9. -- You want to see 0 for process_virtual_memory_low  
  10. -- This indicates that you are not under internal memory pressure  
-- SQL Server Process Address space info
--(shows whether locked pages is enabled, among other things)
SELECT physical_memory_in_use_kb,locked_page_allocations_kb,
page_fault_count, memory_utilization_percentage,
available_commit_limit_kb, process_physical_memory_low,
process_virtual_memory_low
FROM sys.dm_os_process_memory WITH (NOLOCK) OPTION (RECOMPILE);
-- You want to see 0 for process_physical_memory_low
-- You want to see 0 for process_virtual_memory_low
-- This indicates that you are not under internal memory pressure

查看SQL Server是否處於內存壓力的一個經典做法是查看Page Life Expectancy (PLE)，PLE越高越好（MS推薦300爲可接受）：

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  1. -- Page Life Expectancy (PLE) value for default instance  
  2. SELECT cntr_value AS [Page Life Expectancy]  
  3. FROM sys.dm_os_performance_counters WITH (NOLOCK)  
  4. WHERE [object_name] LIKE N'%Buffer Manager%' -- Handles named instances  
  5. AND counter_name = N'Page life expectancy' OPTION (RECOMPILE);  
  6. -- PLE is one way to measure memory pressure.  
  7. -- Higher PLE is better. Watch the trend, not the absolute value.  
-- Page Life Expectancy (PLE) value for default instance
SELECT cntr_value AS [Page Life Expectancy]
FROM sys.dm_os_performance_counters WITH (NOLOCK)
WHERE [object_name] LIKE N'%Buffer Manager%' -- Handles named instances
AND counter_name = N'Page life expectancy' OPTION (RECOMPILE);
-- PLE is one way to measure memory pressure.
-- Higher PLE is better. Watch the trend, not the absolute value.

下面的查詢返回Memory Grants Outstanding：

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  1. -- Memory Grants Outstanding value for default instance  
  2. SELECT cntr_value AS [Memory Grants Outstanding]  
  3. FROM sys.dm_os_performance_counters WITH (NOLOCK)  
  4. WHERE [object_name] LIKE N'%Memory Manager%' -- Handles named instances  
  5. AND counter_name = N'Memory Grants Outstanding' OPTION (RECOMPILE);  
  6. -- Memory Grants Outstanding above zero  
  7. -- for a sustained period is a secondary indicator of memory pressure  
-- Memory Grants Outstanding value for default instance
SELECT cntr_value AS [Memory Grants Outstanding]
FROM sys.dm_os_performance_counters WITH (NOLOCK)
WHERE [object_name] LIKE N'%Memory Manager%' -- Handles named instances
AND counter_name = N'Memory Grants Outstanding' OPTION (RECOMPILE);
-- Memory Grants Outstanding above zero
-- for a sustained period is a secondary indicator of memory pressure

下面的查詢返回Memory Grants Pending：

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  1. -- Memory Grants Pending value for default instance  
  2. SELECT cntr_value AS [Memory Grants Pending]  
  3. FROM sys.dm_os_performance_counters WITH (NOLOCK)  
  4. WHERE [object_name] LIKE N'%Memory Manager%' -- Handles named instances  
  5. AND counter_name = N'Memory Grants Pending' OPTION (RECOMPILE);  
  6. -- Memory Grants Pending above zero  
  7. -- for a sustained period is an extremely strong indicator of memory pressure  
-- Memory Grants Pending value for default instance
SELECT cntr_value AS [Memory Grants Pending]
FROM sys.dm_os_performance_counters WITH (NOLOCK)
WHERE [object_name] LIKE N'%Memory Manager%' -- Handles named instances
AND counter_name = N'Memory Grants Pending' OPTION (RECOMPILE);
-- Memory Grants Pending above zero
-- for a sustained period is an extremely strong indicator of memory pressure

當你從上面3個查詢中看到任何內存壓力，要進一步查看整體的內存使用狀況：

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  1. -- Memory Clerk Usage for instance  
  2. -- Look for high value for CACHESTORE_SQLCP (Ad-hoc query plans)  
  3. SELECT TOP(10) [type] AS [Memory Clerk Type],  
  4. SUM(pages_kb) AS [SPA Mem, Kb]  
  5. FROM sys.dm_os_memory_clerks WITH (NOLOCK)  
  6. GROUP BY [type]  
  7. ORDER BY SUM(pages_kb) DESC OPTION (RECOMPILE);  
  8. -- CACHESTORE_SQLCP SQL Plans  
  9. -- These are cached SQL statements or batches that  
  10. -- aren't in stored procedures, functions and triggers  
  11. --  
  12. -- CACHESTORE_OBJCP Object Plans  
  13. -- These are compiled plans for  
  14. -- stored procedures, functions and triggers  
  15. --  
  16. -- CACHESTORE_PHDR Algebrizer Trees  
  17. -- An algebrizer tree is the parsed SQL text  
  18. -- that resolves the table and column names  
-- Memory Clerk Usage for instance
-- Look for high value for CACHESTORE_SQLCP (Ad-hoc query plans)
SELECT TOP(10) [type] AS [Memory Clerk Type],
SUM(pages_kb) AS [SPA Mem, Kb]
FROM sys.dm_os_memory_clerks WITH (NOLOCK)
GROUP BY [type]
ORDER BY SUM(pages_kb) DESC OPTION (RECOMPILE);
-- CACHESTORE_SQLCP SQL Plans
-- These are cached SQL statements or batches that
-- aren't in stored procedures, functions and triggers
--
-- CACHESTORE_OBJCP Object Plans
-- These are compiled plans for
-- stored procedures, functions and triggers
--
-- CACHESTORE_PHDR Algebrizer Trees
-- An algebrizer tree is the parsed SQL text
-- that resolves the table and column names

如果你看到CACHESTORE_SQLCP memory clerk使用很多內存，那麼你可以確定在Procedure緩存裏是否有很多隻用一次且佔用了大量內存的ad hoc查詢計劃：

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  1. -- Find single-use, ad-hoc queries that are bloating the plan cache  
  2. SELECT TOP(20) [text] AS [QueryText], cp.size_in_bytes  
  3. FROM sys.dm_exec_cached_plans AS cp WITH (NOLOCK)  
  4. CROSS APPLY sys.dm_exec_sql_text(plan_handle)  
  5. WHERE cp.cacheobjtype = N'Compiled Plan'  
  6. AND cp.objtype = N'Adhoc'  
  7. AND cp.usecounts = 1  
  8. ORDER BY cp.size_in_bytes DESC OPTION (RECOMPILE);  
  9. -- Gives you the text and size of single-use ad-hoc queries that  
  10. -- waste space in the plan cache  
  11. -- Enabling 'optimize for ad hoc workloads' for the instance  
  12. -- can help (SQL Server 2008 and above only)  
  13. -- Enabling forced parameterization for the database can help, but test first!  
-- Find single-use, ad-hoc queries that are bloating the plan cache
SELECT TOP(20) [text] AS [QueryText], cp.size_in_bytes
FROM sys.dm_exec_cached_plans AS cp WITH (NOLOCK)
CROSS APPLY sys.dm_exec_sql_text(plan_handle)
WHERE cp.cacheobjtype = N'Compiled Plan'
AND cp.objtype = N'Adhoc'
AND cp.usecounts = 1
ORDER BY cp.size_in_bytes DESC OPTION (RECOMPILE);
-- Gives you the text and size of single-use ad-hoc queries that
-- waste space in the plan cache
-- Enabling 'optimize for ad hoc workloads' for the instance
-- can help (SQL Server 2008 and above only)
-- Enabling forced parameterization for the database can help, but test first!

數據庫級別的查詢

切換到特定用戶數據庫：

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  1. -- Database specific queries ******************************************************  
  2. -- **** Switch to a user database *****  
  3. USE YourDatabaseName;  
  4. GO  
-- Database specific queries ******************************************************
-- **** Switch to a user database *****
USE YourDatabaseName;
GO

查詢數據庫大小：

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  1. -- Individual File Sizes and space available for current database  
  2. SELECT name AS [File Name], physical_name AS [Physical Name], size/128.0 AS [Total  
  3. Size in MB],  
  4. size/128.0 - CAST(FILEPROPERTY(name, 'SpaceUsed') AS int)/128.0 AS [Available Space  
  5. In MB], [file_id]  
  6. FROM sys.database_files WITH (NOLOCK) OPTION (RECOMPILE);  
  7. -- Look at how large and how full the files are and where they are located  
  8. -- Make sure the transaction log is not full!!  
-- Individual File Sizes and space available for current database
SELECT name AS [File Name], physical_name AS [Physical Name], size/128.0 AS [Total
Size in MB],
size/128.0 - CAST(FILEPROPERTY(name, 'SpaceUsed') AS int)/128.0 AS [Available Space
In MB], [file_id]
FROM sys.database_files WITH (NOLOCK) OPTION (RECOMPILE);
-- Look at how large and how full the files are and where they are located
-- Make sure the transaction log is not full!!

查看事務日誌大小及空間使用：

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  1. -- Get transaction log size and space information for the current database  
  2. SELECT DB_NAME(database_id) AS [Database Name], database_id,  
  3. CAST((total_log_size_in_bytes/1048576.0) AS DECIMAL(10,1))  
  4. AS [Total_log_size(MB)],  
  5. CAST((used_log_space_in_bytes/1048576.0) AS DECIMAL(10,1))  
  6. AS [Used_log_space(MB)],  
  7. CAST(used_log_space_in_percent AS DECIMAL(10,1)) AS [Used_log_space(%)]  
  8. FROM sys.dm_db_log_space_usage WITH (NOLOCK) OPTION (RECOMPILE);  
  9. -- Another way to look at transaction log file size and space  
-- Get transaction log size and space information for the current database
SELECT DB_NAME(database_id) AS [Database Name], database_id,
CAST((total_log_size_in_bytes/1048576.0) AS DECIMAL(10,1))
AS [Total_log_size(MB)],
CAST((used_log_space_in_bytes/1048576.0) AS DECIMAL(10,1))
AS [Used_log_space(MB)],
CAST(used_log_space_in_percent AS DECIMAL(10,1)) AS [Used_log_space(%)]
FROM sys.dm_db_log_space_usage WITH (NOLOCK) OPTION (RECOMPILE);
-- Another way to look at transaction log file size and space

按文件蒐集I/O統計：

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  1. -- I/O Statistics by file for the current database  
  2. SELECT DB_NAME(DB_ID()) AS [Database Name],[file_id], num_of_reads, num_of_writes,  
  3. io_stall_read_ms, io_stall_write_ms,  
  4. CAST(100. * io_stall_read_ms/(io_stall_read_ms + io_stall_write_ms)  
  5. AS DECIMAL(10,1)) AS [IO Stall Reads Pct],  
  6. CAST(100. * io_stall_write_ms/(io_stall_write_ms + io_stall_read_ms)  
  7. AS DECIMAL(10,1)) AS [IO Stall Writes Pct],  
  8. (num_of_reads + num_of_writes) AS [Writes + Reads], num_of_bytes_read,  
  9. num_of_bytes_written,  
  10. CAST(100. * num_of_reads/(num_of_reads + num_of_writes) AS DECIMAL(10,1))  
  11. AS [# Reads Pct],  
  12. CAST(100. * num_of_writes/(num_of_reads + num_of_writes) AS DECIMAL(10,1))  
  13. AS [# Write Pct],  
  14. CAST(100. * num_of_bytes_read/(num_of_bytes_read + num_of_bytes_written)  
  15. AS DECIMAL(10,1)) AS [Read Bytes Pct],  
  16. CAST(100. * num_of_bytes_written/(num_of_bytes_read + num_of_bytes_written)  
  17. AS DECIMAL(10,1)) AS [Written Bytes Pct]  
  18. FROM sys.dm_io_virtual_file_stats(DB_ID(), NULL) OPTION (RECOMPILE);  
  19. -- This helps you characterize your workload better from an I/O perspective  
-- I/O Statistics by file for the current database
SELECT DB_NAME(DB_ID()) AS [Database Name],[file_id], num_of_reads, num_of_writes,
io_stall_read_ms, io_stall_write_ms,
CAST(100. * io_stall_read_ms/(io_stall_read_ms + io_stall_write_ms)
AS DECIMAL(10,1)) AS [IO Stall Reads Pct],
CAST(100. * io_stall_write_ms/(io_stall_write_ms + io_stall_read_ms)
AS DECIMAL(10,1)) AS [IO Stall Writes Pct],
(num_of_reads + num_of_writes) AS [Writes + Reads], num_of_bytes_read,
num_of_bytes_written,
CAST(100. * num_of_reads/(num_of_reads + num_of_writes) AS DECIMAL(10,1))
AS [# Reads Pct],
CAST(100. * num_of_writes/(num_of_reads + num_of_writes) AS DECIMAL(10,1))
AS [# Write Pct],
CAST(100. * num_of_bytes_read/(num_of_bytes_read + num_of_bytes_written)
AS DECIMAL(10,1)) AS [Read Bytes Pct],
CAST(100. * num_of_bytes_written/(num_of_bytes_read + num_of_bytes_written)
AS DECIMAL(10,1)) AS [Written Bytes Pct]
FROM sys.dm_io_virtual_file_stats(DB_ID(), NULL) OPTION (RECOMPILE);
-- This helps you characterize your workload better from an I/O perspective

查看事務日誌Virtual Log File (VLF)計數：

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  1. -- Get VLF count for transaction log for the current database,  
  2. -- number of rows equals the VLF count. Lower is better!  
  3. DBCC LOGINFO;  
  4. -- High VLF counts can affect write performance  
  5. -- and they can make database restore and recovery take much longer  
-- Get VLF count for transaction log for the current database,
-- number of rows equals the VLF count. Lower is better!
DBCC LOGINFO;
-- High VLF counts can affect write performance
-- and they can make database restore and recovery take much longer

事務日誌中如果有大量VLF，就會影響寫入事務日誌的性能，更重要的是影響恢復數據庫的時間。
查看特定數據庫上的查詢活動：

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  1. -- Top cached queries by Execution Count (SQL Server 2012)  
  2. SELECT qs.execution_count, qs.total_rows, qs.last_rows, qs.min_rows, qs.max_rows,  
  3. qs.last_elapsed_time, qs.min_elapsed_time, qs.max_elapsed_time,  
  4. SUBSTRING(qt.TEXT,qs.statement_start_offset/2 +1,  
  5. (CASE WHEN qs.statement_end_offset = -1  
  6. THEN LEN(CONVERT(NVARCHAR(MAX), qt.TEXT)) * 2  
  7. ELSE qs.statement_end_offset END - qs.statement_start_offset)/2)  
  8. AS query_text  
  9. FROM sys.dm_exec_query_stats AS qs WITH (NOLOCK)  
  10. CROSS APPLY sys.dm_exec_sql_text(qs.sql_handle) AS qt  
  11. ORDER BY qs.execution_count DESC OPTION (RECOMPILE);  
  12. -- Uses several new rows returned columns  
  13. -- to help troubleshoot performance problems  
-- Top cached queries by Execution Count (SQL Server 2012)
SELECT qs.execution_count, qs.total_rows, qs.last_rows, qs.min_rows, qs.max_rows,
qs.last_elapsed_time, qs.min_elapsed_time, qs.max_elapsed_time,
SUBSTRING(qt.TEXT,qs.statement_start_offset/2 +1,
(CASE WHEN qs.statement_end_offset = -1
THEN LEN(CONVERT(NVARCHAR(MAX), qt.TEXT)) * 2
ELSE qs.statement_end_offset END - qs.statement_start_offset)/2)
AS query_text
FROM sys.dm_exec_query_stats AS qs WITH (NOLOCK)
CROSS APPLY sys.dm_exec_sql_text(qs.sql_handle) AS qt
ORDER BY qs.execution_count DESC OPTION (RECOMPILE);
-- Uses several new rows returned columns
-- to help troubleshoot performance problems

查看緩存的存儲過程：

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  1. -- Top Cached SPs By Execution Count (SQL Server 2012)  
  2. SELECT TOP(250) p.name AS [SP Name], qs.execution_count,  
  3. ISNULL(qs.execution_count/DATEDIFF(Second, qs.cached_time, GETDATE()), 0)  
  4. AS [Calls/Second],  
  5. qs.total_worker_time/qs.execution_count AS [AvgWorkerTime],  
  6. qs.total_worker_time AS [TotalWorkerTime],qs.total_elapsed_time,  
  7. qs.total_elapsed_time/qs.execution_count AS [avg_elapsed_time],  
  8. qs.cached_time  
  9. FROM sys.procedures AS p WITH (NOLOCK)  
  10. INNER JOIN sys.dm_exec_procedure_stats AS qs WITH (NOLOCK)  
  11. ON p.[object_id] = qs.[object_id]  
  12. WHERE qs.database_id = DB_ID()  
  13. ORDER BY qs.execution_count DESC OPTION (RECOMPILE);  
  14. -- Tells you which cached stored procedures are called the most often  
  15. -- This helps you characterize and baseline your workload  
-- Top Cached SPs By Execution Count (SQL Server 2012)
SELECT TOP(250) p.name AS [SP Name], qs.execution_count,
ISNULL(qs.execution_count/DATEDIFF(Second, qs.cached_time, GETDATE()), 0)
AS [Calls/Second],
qs.total_worker_time/qs.execution_count AS [AvgWorkerTime],
qs.total_worker_time AS [TotalWorkerTime],qs.total_elapsed_time,
qs.total_elapsed_time/qs.execution_count AS [avg_elapsed_time],
qs.cached_time
FROM sys.procedures AS p WITH (NOLOCK)
INNER JOIN sys.dm_exec_procedure_stats AS qs WITH (NOLOCK)
ON p.[object_id] = qs.[object_id]
WHERE qs.database_id = DB_ID()
ORDER BY qs.execution_count DESC OPTION (RECOMPILE);
-- Tells you which cached stored procedures are called the most often
-- This helps you characterize and baseline your workload

查看存儲過程在緩存裏待多長時間（Cached_time）：

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  1. -- Top Cached SPs By Avg Elapsed Time (SQL Server 2012)  
  2. SELECT TOP(25) p.name AS [SP Name], qs.total_elapsed_time/qs.execution_count  
  3. AS [avg_elapsed_time], qs.total_elapsed_time, qs.execution_count,  
  4. ISNULL(qs.execution_count/DATEDIFF(Second, qs.cached_time,  
  5. GETDATE()), 0) AS [Calls/Second],  
  6. qs.total_worker_time/qs.execution_count AS [AvgWorkerTime],  
  7. qs.total_worker_time AS [TotalWorkerTime], qs.cached_time  
  8. FROM sys.procedures AS p WITH (NOLOCK)  
  9. INNER JOIN sys.dm_exec_procedure_stats AS qs WITH (NOLOCK)  
  10. ON p.[object_id] = qs.[object_id]  
  11. WHERE qs.database_id = DB_ID()  
  12. ORDER BY avg_elapsed_time DESC OPTION (RECOMPILE);  
  13. -- This helps you find long-running cached stored procedures that  
  14. -- may be easy to optimize with standard query tuning techniques  
-- Top Cached SPs By Avg Elapsed Time (SQL Server 2012)
SELECT TOP(25) p.name AS [SP Name], qs.total_elapsed_time/qs.execution_count
AS [avg_elapsed_time], qs.total_elapsed_time, qs.execution_count,
ISNULL(qs.execution_count/DATEDIFF(Second, qs.cached_time,
GETDATE()), 0) AS [Calls/Second],
qs.total_worker_time/qs.execution_count AS [AvgWorkerTime],
qs.total_worker_time AS [TotalWorkerTime], qs.cached_time
FROM sys.procedures AS p WITH (NOLOCK)
INNER JOIN sys.dm_exec_procedure_stats AS qs WITH (NOLOCK)
ON p.[object_id] = qs.[object_id]
WHERE qs.database_id = DB_ID()
ORDER BY avg_elapsed_time DESC OPTION (RECOMPILE);
-- This helps you find long-running cached stored procedures that
-- may be easy to optimize with standard query tuning techniques

從整體CPU角度查看最耗時的存儲過程：

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  1. -- Top Cached SPs By Total Worker time (SQL Server 2012).  
  2. -- Worker time relates to CPU cost  
  3. SELECT TOP(25) p.name AS [SP Name], qs.total_worker_time AS [TotalWorkerTime],  
  4. qs.total_worker_time/qs.execution_count AS [AvgWorkerTime], qs.execution_count,  
  5. ISNULL(qs.execution_count/DATEDIFF(Second, qs.cached_time, GETDATE()), 0)  
  6. AS [Calls/Second],qs.total_elapsed_time, qs.total_elapsed_time/qs.execution_count  
  7. AS [avg_elapsed_time], qs.cached_time  
  8. FROM sys.procedures AS p WITH (NOLOCK)  
  9. INNER JOIN sys.dm_exec_procedure_stats AS qs WITH (NOLOCK)  
  10. ON p.[object_id] = qs.[object_id]  
  11. WHERE qs.database_id = DB_ID()  
  12. ORDER BY qs.total_worker_time DESC OPTION (RECOMPILE);  
  13. -- This helps you find the most expensive cached  
  14. -- stored procedures from a CPU perspective  
  15. -- You should look at this if you see signs of CPU pressure  
-- Top Cached SPs By Total Worker time (SQL Server 2012).
-- Worker time relates to CPU cost
SELECT TOP(25) p.name AS [SP Name], qs.total_worker_time AS [TotalWorkerTime],
qs.total_worker_time/qs.execution_count AS [AvgWorkerTime], qs.execution_count,
ISNULL(qs.execution_count/DATEDIFF(Second, qs.cached_time, GETDATE()), 0)
AS [Calls/Second],qs.total_elapsed_time, qs.total_elapsed_time/qs.execution_count
AS [avg_elapsed_time], qs.cached_time
FROM sys.procedures AS p WITH (NOLOCK)
INNER JOIN sys.dm_exec_procedure_stats AS qs WITH (NOLOCK)
ON p.[object_id] = qs.[object_id]
WHERE qs.database_id = DB_ID()
ORDER BY qs.total_worker_time DESC OPTION (RECOMPILE);
-- This helps you find the most expensive cached
-- stored procedures from a CPU perspective
-- You should look at this if you see signs of CPU pressure

從邏輯度的角度查看緩存的存儲過程相關的信息：

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  1. -- Top Cached SPs By Total Logical Reads (SQL Server 2012).  
  2. -- Logical reads relate to memory pressure  
  3. SELECT TOP(25) p.name AS [SP Name], qs.total_logical_reads  
  4. AS [TotalLogicalReads], qs.total_logical_reads/qs.execution_count  
  5. AS [AvgLogicalReads],qs.execution_count,  
  6. ISNULL(qs.execution_count/DATEDIFF(Second, qs.cached_time, GETDATE()), 0)  
  7. AS [Calls/Second], qs.total_elapsed_time,qs.total_elapsed_time/qs.execution_count  
  8. AS [avg_elapsed_time], qs.cached_time  
  9. FROM sys.procedures AS p WITH (NOLOCK)  
  10. INNER JOIN sys.dm_exec_procedure_stats AS qs WITH (NOLOCK)  
  11. ON p.[object_id] = qs.[object_id]  
  12. WHERE qs.database_id = DB_ID()  
  13. ORDER BY qs.total_logical_reads DESC OPTION (RECOMPILE);  
  14. -- This helps you find the most expensive cached  
  15. -- stored procedures from a memory perspective  
  16. -- You should look at this if you see signs of memory pressure  
-- Top Cached SPs By Total Logical Reads (SQL Server 2012).
-- Logical reads relate to memory pressure
SELECT TOP(25) p.name AS [SP Name], qs.total_logical_reads
AS [TotalLogicalReads], qs.total_logical_reads/qs.execution_count
AS [AvgLogicalReads],qs.execution_count,
ISNULL(qs.execution_count/DATEDIFF(Second, qs.cached_time, GETDATE()), 0)
AS [Calls/Second], qs.total_elapsed_time,qs.total_elapsed_time/qs.execution_count
AS [avg_elapsed_time], qs.cached_time
FROM sys.procedures AS p WITH (NOLOCK)
INNER JOIN sys.dm_exec_procedure_stats AS qs WITH (NOLOCK)
ON p.[object_id] = qs.[object_id]
WHERE qs.database_id = DB_ID()
ORDER BY qs.total_logical_reads DESC OPTION (RECOMPILE);
-- This helps you find the most expensive cached
-- stored procedures from a memory perspective
-- You should look at this if you see signs of memory pressure

從物理度的角度查看最耗時的存儲過程：

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  1. -- Top Cached SPs By Total Physical Reads (SQL Server 2012).  
  2. -- Physical reads relate to disk I/O pressure  
  3. SELECT TOP(25) p.name AS [SP Name],qs.total_physical_reads  
  4. AS [TotalPhysicalReads],qs.total_physical_reads/qs.execution_count  
  5. AS [AvgPhysicalReads], qs.execution_count, qs.total_logical_reads,  
  6. qs.total_elapsed_time, qs.total_elapsed_time/qs.execution_count  
  7. AS [avg_elapsed_time], qs.cached_time  
  8. FROM sys.procedures AS p WITH (NOLOCK)  
  9. INNER JOIN sys.dm_exec_procedure_stats AS qs WITH (NOLOCK)  
  10. ON p.[object_id] = qs.[object_id]  
  11. WHERE qs.database_id = DB_ID()  
  12. AND qs.total_physical_reads > 0  
  13. ORDER BY qs.total_physical_reads DESC,  
  14. qs.total_logical_reads DESC OPTION (RECOMPILE);  
  15. -- This helps you find the most expensive cached  
  16. -- stored procedures from a read I/O perspective  
  17. -- You should look at this if you see signs of I/O pressure or of memory pressure  
-- Top Cached SPs By Total Physical Reads (SQL Server 2012).
-- Physical reads relate to disk I/O pressure
SELECT TOP(25) p.name AS [SP Name],qs.total_physical_reads
AS [TotalPhysicalReads],qs.total_physical_reads/qs.execution_count
AS [AvgPhysicalReads], qs.execution_count, qs.total_logical_reads,
qs.total_elapsed_time, qs.total_elapsed_time/qs.execution_count
AS [avg_elapsed_time], qs.cached_time
FROM sys.procedures AS p WITH (NOLOCK)
INNER JOIN sys.dm_exec_procedure_stats AS qs WITH (NOLOCK)
ON p.[object_id] = qs.[object_id]
WHERE qs.database_id = DB_ID()
AND qs.total_physical_reads > 0
ORDER BY qs.total_physical_reads DESC,
qs.total_logical_reads DESC OPTION (RECOMPILE);
-- This helps you find the most expensive cached
-- stored procedures from a read I/O perspective
-- You should look at this if you see signs of I/O pressure or of memory pressure

從邏輯寫來看最耗時的緩存存儲過程：

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  1. -- Top Cached SPs By Total Logical Writes (SQL Server 2012).  
  2. -- Logical writes relate to both memory and disk I/O pressure  
  3. SELECT TOP(25) p.name AS [SP Name], qs.total_logical_writes  
  4. AS [TotalLogicalWrites], qs.total_logical_writes/qs.execution_count  
  5. AS [AvgLogicalWrites], qs.execution_count,  
  6. ISNULL(qs.execution_count/DATEDIFF(Second, qs.cached_time, GETDATE()), 0)  
  7. AS [Calls/Second],qs.total_elapsed_time, qs.total_elapsed_time/qs.execution_count  
  8. AS [avg_elapsed_time], qs.cached_time  
  9. FROM sys.procedures AS p WITH (NOLOCK)  
  10. INNER JOIN sys.dm_exec_procedure_stats AS qs WITH (NOLOCK)  
  11. ON p.[object_id] = qs.[object_id]  
  12. WHERE qs.database_id = DB_ID()  
  13. ORDER BY qs.total_logical_writes DESC OPTION (RECOMPILE);  
  14. -- This helps you find the most expensive cached  
  15. -- stored procedures from a write I/O perspective  
  16. -- You should look at this if you see signs of I/O pressure or of memory pressure  
-- Top Cached SPs By Total Logical Writes (SQL Server 2012).
-- Logical writes relate to both memory and disk I/O pressure
SELECT TOP(25) p.name AS [SP Name], qs.total_logical_writes
AS [TotalLogicalWrites], qs.total_logical_writes/qs.execution_count
AS [AvgLogicalWrites], qs.execution_count,
ISNULL(qs.execution_count/DATEDIFF(Second, qs.cached_time, GETDATE()), 0)
AS [Calls/Second],qs.total_elapsed_time, qs.total_elapsed_time/qs.execution_count
AS [avg_elapsed_time], qs.cached_time
FROM sys.procedures AS p WITH (NOLOCK)
INNER JOIN sys.dm_exec_procedure_stats AS qs WITH (NOLOCK)
ON p.[object_id] = qs.[object_id]
WHERE qs.database_id = DB_ID()
ORDER BY qs.total_logical_writes DESC OPTION (RECOMPILE);
-- This helps you find the most expensive cached
-- stored procedures from a write I/O perspective
-- You should look at this if you see signs of I/O pressure or of memory pressure

從平均I/O來看緩存的存儲過程中最耗資源的語句：

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  1. -- Lists the top statements by average input/output  
  2. -- usage for the current database  
  3. SELECT TOP(50) OBJECT_NAME(qt.objectid) AS [SP Name],  
  4. (qs.total_logical_reads + qs.total_logical_writes) /qs.execution_count  
  5. AS [Avg IO],SUBSTRING(qt.[text],qs.statement_start_offset/2,  
  6. (CASE  
  7. WHEN qs.statement_end_offset = -1  
  8. THEN LEN(CONVERT(nvarchar(max), qt.[text])) * 2  
  9. ELSE qs.statement_end_offset  
  10. END - qs.statement_start_offset)/2) AS [Query Text]  
  11. FROM sys.dm_exec_query_stats AS qs WITH (NOLOCK)  
  12. CROSS APPLY sys.dm_exec_sql_text(qs.sql_handle) AS qt  
  13. WHERE qt.[dbid] = DB_ID()  
  14. ORDER BY [Avg IO] DESC OPTION (RECOMPILE);  
  15. -- Helps you find the most expensive statements for I/O by SP  
-- Lists the top statements by average input/output
-- usage for the current database
SELECT TOP(50) OBJECT_NAME(qt.objectid) AS [SP Name],
(qs.total_logical_reads + qs.total_logical_writes) /qs.execution_count
AS [Avg IO],SUBSTRING(qt.[text],qs.statement_start_offset/2,
(CASE
WHEN qs.statement_end_offset = -1
THEN LEN(CONVERT(nvarchar(max), qt.[text])) * 2
ELSE qs.statement_end_offset
END - qs.statement_start_offset)/2) AS [Query Text]
FROM sys.dm_exec_query_stats AS qs WITH (NOLOCK)
CROSS APPLY sys.dm_exec_sql_text(qs.sql_handle) AS qt
WHERE qt.[dbid] = DB_ID()
ORDER BY [Avg IO] DESC OPTION (RECOMPILE);
-- Helps you find the most expensive statements for I/O by SP

查看寫比讀更多的非聚集索引：

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  1. -- Possible Bad NC Indexes (writes > reads)  
  2. SELECT OBJECT_NAME(s.[object_id]) AS [Table Name], i.name AS [Index Name],  
  3. i.index_id,user_updates AS [Total Writes],  
  4. user_seeks + user_scans + user_lookups AS [Total Reads],  
  5. user_updates - (user_seeks + user_scans + user_lookups) AS [Difference]  
  6. FROM sys.dm_db_index_usage_stats AS s WITH (NOLOCK)  
  7. INNER JOIN sys.indexes AS i WITH (NOLOCK)  
  8. ON s.[object_id] = i.[object_id]  
  9. AND i.index_id = s.index_id  
  10. WHERE OBJECTPROPERTY(s.[object_id],'IsUserTable') = 1  
  11. AND s.database_id = DB_ID()  
  12. AND user_updates > (user_seeks + user_scans + user_lookups)  
  13. AND i.index_id > 1  
  14. ORDER BY [Difference] DESC, [Total Writes] DESC, [Total Reads] ASC OPTION  
  15. (RECOMPILE);  
  16. -- Look for indexes with high numbers of writes  
  17. -- and zero or very low numbers of reads  
  18. -- Consider your complete workload  
  19. -- Investigate further before dropping an index!  
-- Possible Bad NC Indexes (writes > reads)
SELECT OBJECT_NAME(s.[object_id]) AS [Table Name], i.name AS [Index Name],
i.index_id,user_updates AS [Total Writes],
user_seeks + user_scans + user_lookups AS [Total Reads],
user_updates - (user_seeks + user_scans + user_lookups) AS [Difference]
FROM sys.dm_db_index_usage_stats AS s WITH (NOLOCK)
INNER JOIN sys.indexes AS i WITH (NOLOCK)
ON s.[object_id] = i.[object_id]
AND i.index_id = s.index_id
WHERE OBJECTPROPERTY(s.[object_id],'IsUserTable') = 1
AND s.database_id = DB_ID()
AND user_updates > (user_seeks + user_scans + user_lookups)
AND i.index_id > 1
ORDER BY [Difference] DESC, [Total Writes] DESC, [Total Reads] ASC OPTION
(RECOMPILE);
-- Look for indexes with high numbers of writes
-- and zero or very low numbers of reads
-- Consider your complete workload
-- Investigate further before dropping an index!

查看缺失的索引信息：

[sql] view plain copy
print?在CODE上查看代碼片派生到我的代碼片
  1. -- Missing Indexes current database by Index Advantage  
  2. SELECT user_seeks * avg_total_user_cost * (avg_user_impact * 0.01)  
  3. AS [index_advantage],  
  4. migs.last_user_seek, mid.[statement] AS [Database.Schema.Table],  
  5. mid.equality_columns, mid.inequality_columns, mid.included_columns,  
  6. migs.unique_compiles, migs.user_seeks, migs.avg_total_user_cost,  
  7. migs.avg_user_impact  
  8. FROM sys.dm_db_missing_index_group_stats AS migs WITH (NOLOCK)  
  9. INNER JOIN sys.dm_db_missing_index_groups AS mig WITH (NOLOCK)  
  10. ON migs.group_handle = mig.index_group_handle  
  11. INNER JOIN sys.dm_db_missing_index_details AS mid WITH (NOLOCK)  
  12. ON mig.index_handle = mid.index_handle  
  13. WHERE mid.database_id = DB_ID() -- Remove this to see for entire instance  
  14. ORDER BY index_advantage DESC OPTION (RECOMPILE);  
  15. -- Look at last user seek time, number of user seeks  
  16. -- to help determine source and importance  
  17. -- SQL Server is overly eager to add included columns, so beware  
  18. -- Do not just blindly add indexes that show up from this query!!!  
-- Missing Indexes current database by Index Advantage
SELECT user_seeks * avg_total_user_cost * (avg_user_impact * 0.01)
AS [index_advantage],
migs.last_user_seek, mid.[statement] AS [Database.Schema.Table],
mid.equality_columns, mid.inequality_columns, mid.included_columns,
migs.unique_compiles, migs.user_seeks, migs.avg_total_user_cost,
migs.avg_user_impact
FROM sys.dm_db_missing_index_group_stats AS migs WITH (NOLOCK)
INNER JOIN sys.dm_db_missing_index_groups AS mig WITH (NOLOCK)
ON migs.group_handle = mig.index_group_handle
INNER JOIN sys.dm_db_missing_index_details AS mid WITH (NOLOCK)
ON mig.index_handle = mid.index_handle
WHERE mid.database_id = DB_ID() -- Remove this to see for entire instance
ORDER BY index_advantage DESC OPTION (RECOMPILE);
-- Look at last user seek time, number of user seeks
-- to help determine source and importance
-- SQL Server is overly eager to add included columns, so beware
-- Do not just blindly add indexes that show up from this query!!!

查看緩存的執行計劃中缺失索引警告：

[sql] view plain copy
print?在CODE上查看代碼片派生到我的代碼片
  1. -- Find missing index warnings for cached plans in the current database  
  2. -- Note: This query could take some time on a busy instance  
  3. SELECT TOP(25) OBJECT_NAME(objectid) AS [ObjectName],query_plan,  
  4. cp.objtype, cp.usecounts  
  5. FROM sys.dm_exec_cached_plans AS cp WITH (NOLOCK)  
  6. CROSS APPLY sys.dm_exec_query_plan(cp.plan_handle) AS qp  
  7. WHERE CAST(query_plan AS NVARCHAR(MAX)) LIKE N'%MissingIndex%'  
  8. AND dbid = DB_ID()  
  9. ORDER BY cp.usecounts DESC OPTION (RECOMPILE);  
  10. -- Helps you connect missing indexes to specific stored procedures or queries  
  11. -- This can help you decide whether to add them or not  
-- Find missing index warnings for cached plans in the current database
-- Note: This query could take some time on a busy instance
SELECT TOP(25) OBJECT_NAME(objectid) AS [ObjectName],query_plan,
cp.objtype, cp.usecounts
FROM sys.dm_exec_cached_plans AS cp WITH (NOLOCK)
CROSS APPLY sys.dm_exec_query_plan(cp.plan_handle) AS qp
WHERE CAST(query_plan AS NVARCHAR(MAX)) LIKE N'%MissingIndex%'
AND dbid = DB_ID()
ORDER BY cp.usecounts DESC OPTION (RECOMPILE);
-- Helps you connect missing indexes to specific stored procedures or queries
-- This can help you decide whether to add them or not

查看SQL Server緩衝池中佔用最多空間的表和索引：

[sql] view plain copy
print?在CODE上查看代碼片派生到我的代碼片
  1. -- Breaks down buffers used by current database  
  2. -- by object (table, index) in the buffer cache  
  3. SELECT OBJECT_NAME(p.[object_id]) AS [ObjectName],  
  4. p.index_id, COUNT(*)/128 AS [Buffer size(MB)], COUNT(*) AS [BufferCount],  
  5. p.data_compression_desc AS [CompressionType]  
  6. FROM sys.allocation_units AS a WITH (NOLOCK)  
  7. INNER JOIN sys.dm_os_buffer_descriptors AS b WITH (NOLOCK)  
  8. ON a.allocation_unit_id = b.allocation_unit_id  
  9. INNER JOIN sys.partitions AS p WITH (NOLOCK)  
  10. ON a.container_id = p.hobt_id  
  11. WHERE b.database_id = CONVERT(int,DB_ID())  
  12. AND p.[object_id] > 100  
  13. GROUP BY p.[object_id], p.index_id, p.data_compression_desc  
  14. ORDER BY [BufferCount] DESC OPTION (RECOMPILE);  
  15. -- Tells you what tables and indexes are  
  16. -- using the most memory in the buffer cache  
-- Breaks down buffers used by current database
-- by object (table, index) in the buffer cache
SELECT OBJECT_NAME(p.[object_id]) AS [ObjectName],
p.index_id, COUNT(*)/128 AS [Buffer size(MB)], COUNT(*) AS [BufferCount],
p.data_compression_desc AS [CompressionType]
FROM sys.allocation_units AS a WITH (NOLOCK)
INNER JOIN sys.dm_os_buffer_descriptors AS b WITH (NOLOCK)
ON a.allocation_unit_id = b.allocation_unit_id
INNER JOIN sys.partitions AS p WITH (NOLOCK)
ON a.container_id = p.hobt_id
WHERE b.database_id = CONVERT(int,DB_ID())
AND p.[object_id] > 100
GROUP BY p.[object_id], p.index_id, p.data_compression_desc
ORDER BY [BufferCount] DESC OPTION (RECOMPILE);
-- Tells you what tables and indexes are
-- using the most memory in the buffer cache

查看數據庫中所有表的大小及數據壓縮狀態：

[sql] view plain copy
print?在CODE上查看代碼片派生到我的代碼片
  1. -- Get Table names, row counts, and compression status  
  2. -- for the clustered index or heap  
  3. SELECT OBJECT_NAME(object_id) AS [ObjectName],  
  4. SUM(Rows) AS [RowCount], data_compression_desc AS [CompressionType]  
  5. FROM sys.partitions WITH (NOLOCK)  
  6. WHERE index_id < 2 --ignore the partitions from the non-clustered index if any  
  7. AND OBJECT_NAME(object_id) NOT LIKE N'sys%'  
  8. AND OBJECT_NAME(object_id) NOT LIKE N'queue_%'  
  9. AND OBJECT_NAME(object_id) NOT LIKE N'filestream_tombstone%'  
  10. AND OBJECT_NAME(object_id) NOT LIKE N'fulltext%'  
  11. AND OBJECT_NAME(object_id) NOT LIKE N'ifts_comp_fragment%'  
  12. AND OBJECT_NAME(object_id) NOT LIKE N'filetable_updates%'  
  13. GROUP BY object_id, data_compression_desc  
  14. ORDER BY SUM(Rows) DESC OPTION (RECOMPILE);  
  15. -- Gives you an idea of table sizes, and possible data compression opportunities  
-- Get Table names, row counts, and compression status
-- for the clustered index or heap
SELECT OBJECT_NAME(object_id) AS [ObjectName],
SUM(Rows) AS [RowCount], data_compression_desc AS [CompressionType]
FROM sys.partitions WITH (NOLOCK)
WHERE index_id < 2 --ignore the partitions from the non-clustered index if any
AND OBJECT_NAME(object_id) NOT LIKE N'sys%'
AND OBJECT_NAME(object_id) NOT LIKE N'queue_%'
AND OBJECT_NAME(object_id) NOT LIKE N'filestream_tombstone%'
AND OBJECT_NAME(object_id) NOT LIKE N'fulltext%'
AND OBJECT_NAME(object_id) NOT LIKE N'ifts_comp_fragment%'
AND OBJECT_NAME(object_id) NOT LIKE N'filetable_updates%'
GROUP BY object_id, data_compression_desc
ORDER BY SUM(Rows) DESC OPTION (RECOMPILE);
-- Gives you an idea of table sizes, and possible data compression opportunities

查看數據庫中所有索引最後一次統計更新的時間：

[sql] view plain copy
print?在CODE上查看代碼片派生到我的代碼片
  1. -- When were Statistics last updated on all indexes?  
  2. SELECT o.name, i.name AS [Index Name],STATS_DATE(i.[object_id],  
  3. i.index_id) AS [Statistics Date], s.auto_created,  
  4. s.no_recompute, s.user_created, st.row_count  
  5. FROM sys.objects AS o WITH (NOLOCK)  
  6. INNER JOIN sys.indexes AS i WITH (NOLOCK)  
  7. ON o.[object_id] = i.[object_id]  
  8. INNER JOIN sys.stats AS s WITH (NOLOCK)  
  9. ON i.[object_id] = s.[object_id]  
  10. AND i.index_id = s.stats_id  
  11. INNER JOIN sys.dm_db_partition_stats AS st WITH (NOLOCK)  
  12. ON o.[object_id] = st.[object_id]  
  13. AND i.[index_id] = st.[index_id]  
  14. WHERE o.[type] = 'U'  
  15. ORDER BY STATS_DATE(i.[object_id], i.index_id) ASC OPTION (RECOMPILE);  
  16. -- Helps discover possible problems with out-of-date statistics  
  17. -- Also gives you an idea which indexes are most active  
-- When were Statistics last updated on all indexes?
SELECT o.name, i.name AS [Index Name],STATS_DATE(i.[object_id],
i.index_id) AS [Statistics Date], s.auto_created,
s.no_recompute, s.user_created, st.row_count
FROM sys.objects AS o WITH (NOLOCK)
INNER JOIN sys.indexes AS i WITH (NOLOCK)
ON o.[object_id] = i.[object_id]
INNER JOIN sys.stats AS s WITH (NOLOCK)
ON i.[object_id] = s.[object_id]
AND i.index_id = s.stats_id
INNER JOIN sys.dm_db_partition_stats AS st WITH (NOLOCK)
ON o.[object_id] = st.[object_id]
AND i.[index_id] = st.[index_id]
WHERE o.[type] = 'U'
ORDER BY STATS_DATE(i.[object_id], i.index_id) ASC OPTION (RECOMPILE);
-- Helps discover possible problems with out-of-date statistics
-- Also gives you an idea which indexes are most active

查看當前數據庫中碎片最多的索引：

[sql] view plain copy
print?在CODE上查看代碼片派生到我的代碼片
  1. -- Get fragmentation info for all indexes  
  2. -- above a certain size in the current database  
  3. -- Note: This could take some time on a very large database  
  4. SELECT DB_NAME(database_id) AS [Database Name],  
  5. OBJECT_NAME(ps.OBJECT_ID) AS [Object Name],  
  6. i.name AS [Index Name], ps.index_id, index_type_desc,  
  7. avg_fragmentation_in_percent, fragment_count, page_count  
  8. FROM sys.dm_db_index_physical_stats(DB_ID(),NULL, NULL, NULL ,'LIMITED') AS ps  
  9. INNER JOIN sys.indexes AS i WITH (NOLOCK)  
  10. ON ps.[object_id] = i.[object_id]  
  11. AND ps.index_id = i.index_id  
  12. WHERE database_id = DB_ID()  
  13. AND page_count > 500  
  14. ORDER BY avg_fragmentation_in_percent DESC OPTION (RECOMPILE);  
  15. -- Helps determine whether you have fragmentation in your relational indexes  
  16. -- and how effective your index maintenance strategy is  
-- Get fragmentation info for all indexes
-- above a certain size in the current database
-- Note: This could take some time on a very large database
SELECT DB_NAME(database_id) AS [Database Name],
OBJECT_NAME(ps.OBJECT_ID) AS [Object Name],
i.name AS [Index Name], ps.index_id, index_type_desc,
avg_fragmentation_in_percent, fragment_count, page_count
FROM sys.dm_db_index_physical_stats(DB_ID(),NULL, NULL, NULL ,'LIMITED') AS ps
INNER JOIN sys.indexes AS i WITH (NOLOCK)
ON ps.[object_id] = i.[object_id]
AND ps.index_id = i.index_id
WHERE database_id = DB_ID()
AND page_count > 500
ORDER BY avg_fragmentation_in_percent DESC OPTION (RECOMPILE);
-- Helps determine whether you have fragmentation in your relational indexes
-- and how effective your index maintenance strategy is

如果你發現超過10%碎片的索引，你就需要決定是重組還是重建它們。重組通常是Online操作，能在任何時間停止。重建可以是Online或Offline操作。在SQL Server 2012中，你可以Online重建聚集索引，而不必考慮表包含什麼類型的數據。收縮數據文件非常消耗資源。不要犯常見的錯誤定期去重建所有索引，這非常浪費資源。你可以在Internet上找一些好的索引維護腳本。Ola Hallengren開發了一個非常好的腳本，你可以從 http://ola.hallengren.com獲取。


http://blog.csdn.net/burgess_liu/article/details/36654597

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