常用的sql

1. 查看連接數：

use master
SELECT program_name,* FROM [Master].[dbo].[SYSPROCESSES] WHERE [DBID] IN(SELECT [DBID]FROM [Master].[dbo].[SYSDATABASES] WHERE NAME='test') order by spid

sysprocesses :  kpid 線程號（內核進程 id）,  spid進程號， lastwaittype

lastwaittype = SOS_SCHEDULER_YIELD  任務執行的時候主動放棄CPU輪詢處理(Windows爲多任務OS),並繼續等待。

如果多個進程有SOS_SCHEDULER_YIELD，說明有CPU壓力

2. 查看有未提交事務的進程

select sysprocesses.open_tran, * from sysprocesses where open_tran>0

3. 查看是否有進程在等待CPU

SELECT scheduler_id, current_tasks_count, runnable_tasks_count   FROM sys.dm_os_schedulers    WHERE scheduler_id < 255 

如果 runnable_tasks_count>0 則可能存在CPU瓶頸

4. 佔CPU時間最多的SQL

SELECT SUBSTRING(qt.TEXT, (qs.statement_start_offset/2)+1,((CASEqs.statement_end_offsetWHEN-1THENDATALENGTH(qt.TEXT)ELSEqs.statement_end_offset
END - qs.statement_start_offset)/2)+1),
      qs.execution_count,qs.total_logical_reads,qs.last_logical_reads,
      qs.total_logical_writes,qs.last_logical_writes,qs.total_worker_time,
      qs.last_worker_time, qs.total_elapsed_time/1000000 total_elapsed_time_in_S,
      qs.last_elapsed_time/1000000 last_elapsed_time_in_S,qs.last_execution_time,
      qp.query_plan
FROM sys.dm_exec_query_stats qs
     CROSS APPLY sys.dm_exec_sql_text(qs.sql_handle)qt
     CROSS APPLY sys.dm_exec_query_plan(qs.plan_handle)qp
ORDER BY qs.total_worker_time DESC -- CPU time

當前緩存的哪些批處理或過程佔用了大部分 CPU 資源

SELECT TOP 50 SUM(qs.total_worker_time) AS total_cpu_time, SUM(qs.execution_count) AS total_execution_count,
       COUNT(*) AS  number_of_statements, qs.sql_handle 
FROM sys.dm_exec_query_stats AS qs
GROUP BY qs.sql_handle
ORDER BY SUM(qs.total_worker_time) DESC

緩存計劃所佔用的 CPU 總使用率

SELECT total_cpu_time, total_execution_count, number_of_statements, s2.text
      --(SELECT SUBSTRING(s2.text, statement_start_offset / 2, ((CASE WHEN statement_end_offset = -1 THEN (LEN(CONVERT(NVARCHAR(MAX), s2.text)) * 2) ELSE statement_end_offset END) - statement_start_offset) / 2) ) AS query_text
FROM (  SELECT TOP 50  SUM(qs.total_worker_time) AS total_cpu_time,  SUM(qs.execution_count) AS total_execution_count,
              COUNT(*) AS  number_of_statements, qs.sql_handle --,
              --MIN(statement_start_offset) AS statement_start_offset, 
              --MAX(statement_end_offset) AS statement_end_offset
        FROM sys.dm_exec_query_stats AS qs
        GROUP BY qs.sql_handle
        ORDER BY SUM(qs.total_worker_time) DESC
      ) AS stats
      CROSS APPLY sys.dm_exec_sql_text(stats.sql_handle) AS s2

顯示 CPU 平均佔用率最高的前 50 個 SQL 語句

SELECT TOP 50 total_worker_time/execution_count AS [Avg CPU Time],
             ( SELECT SUBSTRING(text,statement_start_offset/2,(CASE WHEN statement_end_offset = -1 then LEN(CONVERT(nvarchar(max), text)) * 2 ELSE statement_end_offset end -statement_start_offset)/2) 
               FROM sys.dm_exec_sql_text(sql_handle)) AS query_text, *
FROM sys.dm_exec_query_stats 
ORDER BY [Avg CPU Time] DESC

如果系統存在過多的編譯和重新編譯，可能會導致系統出現與 CPU 相關的性能問題。

過多編譯/重新編譯的

select * from sys.dm_exec_query_optimizer_info where counter = 'optimizations' or counter = 'elapsed time'

已重新編譯的前 25 個存儲過程

select top 25  sql_text.text, sql_handle, plan_generation_num, execution_count, dbid, objectid 
from sys.dm_exec_query_stats a cross apply sys.dm_exec_sql_text(sql_handle) as sql_text
where plan_generation_num > 1
order by plan_generation_num desc

哪個查詢佔用了最多的 CPU 累計使用率

SELECT highest_cpu_queries.plan_handle, highest_cpu_queries.total_worker_time, q.dbid, q.objectid, q.number, q.encrypted, q.[text]
from ( select top 50 qs.plan_handle, qs.total_worker_time from sys.dm_exec_query_stats qs order by qs.total_worker_time desc) as highest_cpu_queries
     cross apply sys.dm_exec_sql_text(plan_handle) as q
order by highest_cpu_queries.total_worker_time desc

可能佔用大量 CPU 使用率的運算符

select *
from sys.dm_exec_cached_plans cross apply sys.dm_exec_query_plan(plan_handle)
where cast(query_plan as nvarchar(max)) like '%Sort%'  or cast(query_plan as nvarchar(max)) like '%Hash Match%'

5.快速獲取表的行數

select rows from sysindexes where id=object_id('weblog') and indid in(0,1)

6.清除緩存和執行計劃緩存

DBCC DROPCLEANBUFFERS
DBCC FREEPROCCACHE

7.清空日誌

     DUMP TRANSACTION 庫名 WITH NO_LOG

8.截斷事務日誌

    BACKUP LOG vttest TO DISK='X:\sql2008Data\vttest_log.bak' WITH INIT,NO_TRUNCATE 

9.收縮數據庫

    DBCC   SHRINKDATABASE(數據庫名)

10.收縮文件

      select   *   from   sysfiles   --找到文件ID
      DBCC   SHRINKFILE(2)   --吧ID作爲參數傳入

11.查詢所有表的大小

create PROCEDURE get_tableinfo AS

if not exists(select * from dbo.sysobjects where id=object_id(N'[dbo].[tablespaceinfo]')and OBJECTPROPERTY(id,N'IsUserTable')=1)

create table tablespaceinfo(nameinfo varchar(50), rowsinfo int, reserved varchar(20),
                            datainfo varchar(20), index_size varchar(20), unused varchar(20))
delete from tablespaceinfo--清空數據表
declare @tablename varchar(255) --表名稱
declare @cmdsql varchar(500)
DECLARE Info_cursor CURSOR FOR
select o.name from dbo.sysobjects o where OBJECTPROPERTY(o.id,N'IsTable')=1  and o.name not like N'#%%' order by o.name
OPEN Info_cursor

FETCH NEXT FROM Info_cursor INTO @tablename
WHILE @@FETCH_STATUS=0
BEGIN
  if exists(select * from dbo.sysobjects where id=object_id(@tablename) and OBJECTPROPERTY(id,N'IsUserTable')=1)
    execute sp_executesql N'insert into tablespaceinfo exec sp_spaceused @tbname', N'@tbname varchar(255)', @tbname=@tablename
  FETCH NEXT FROM Info_cursor
  INTO @tablename
END
CLOSE Info_cursor
DEALLOCATE Info_cursor
GO

--執行存儲過程
exec get_tableinfo
--查詢運行該存儲過程後得到的結果
select * from tablespaceinfo order by cast(left(ltrim(rtrim(reserved)) , len(ltrim(rtrim(reserved)))-2) as int) desc

12.查看阻塞

use master
go
declare @spid int,@bl int
DECLARE s_cur CURSOR FOR
    select  0 ,blocked
    from (select * from sysprocesses where  blocked>0 ) a
    where not exists(select * from (select * from sysprocesses where  blocked>0 ) b
    where a.blocked=spid)
    union select spid,blocked from sysprocesses where  blocked>0
    OPEN s_cur
FETCH NEXT FROM s_cur INTO @spid,@bl
WHILE @@FETCH_STATUS = 0
begin
if @spid =0
            select ' 引起數據庫死鎖的是 : '+ CAST(@bl AS VARCHAR(10)) + ' 進程號 , 其執行的 SQL 語法如下 '
else
            select ' 進程號 SPID ： '+ CAST(@spid AS VARCHAR(10))+ ' 被 ' + ' 進程號 SPID ： '+ CAST(@bl AS VARCHAR(10)) +' 阻塞 , 其當前進程執行的 SQL 語法如下 '
DBCC INPUTBUFFER (@bl )
FETCH NEXT FROM s_cur INTO @spid,@bl
end
CLOSE s_cur
DEALLOCATE s_cur

exec sp_who2