Sql Server CPU 效能排查及最佳化的相關 Sql

Sql Server CPU 效能排查及最佳化的相關 Sql 語句，非常好的SQL語句，記錄於此：

--Begin Cpu 分析最佳化的相關 Sql 

--使用DMV來分析SQL Server啟動以來累計使用CPU資源最多的語句。例如下面的語句就可以列出前50名。
select 
    c.last_execution_time,c.execution_count,c.total_logical_reads,c.total_logical_writes,c.total_elapsed_time,c.last_elapsed_time, 
    q.[text]
from 
    (select top 50 qs.*
from sys.dm_exec_query_stats qs
order by qs.total_worker_time desc) as c
cross apply sys.dm_exec_sql_text(plan_handle) as q
order by c.total_worker_time desc
go

-- 返回最經常啟動並執行100條語句
SELECT TOP 100 cp.cacheobjtype,cp.usecounts,cp.size_in_bytes,qs.statement_start_offset,qs.statement_end_offset,qt.dbid    ,qt.objectid
                        ,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 statement 
FROM sys.dm_exec_query_stats qs
cross apply sys.dm_exec_sql_text(qs.sql_handle) as qt
inner join sys.dm_exec_cached_plans as cp on qs.plan_handle=cp.plan_handle
where cp.plan_handle=qs.plan_handle
and cp.usecounts>4
ORDER BY [dbid],[Usecounts] DESC

-- 返回做IO數目最多的50條語句以及它們的執行計畫
select top 50 
    (total_logical_reads/execution_count) as avg_logical_reads,
    (total_logical_writes/execution_count) as avg_logical_writes,
    (total_physical_reads/execution_count) as avg_phys_reads,
     Execution_count, 
    statement_start_offset as stmt_start_offset, statement_end_offset as stmt_end_offset,
substring(sql_text.text, (statement_start_offset/2), 
case 
when (statement_end_offset -statement_start_offset)/2 <=0 then 64000
else (statement_end_offset -statement_start_offset)/2 end) as exec_statement,  sql_text.text,plan_text.*
from sys.dm_exec_query_stats  
cross apply sys.dm_exec_sql_text(sql_handle) as sql_text
cross apply sys.dm_exec_query_plan(plan_handle) as plan_text
order by 
 (total_logical_reads + total_logical_writes) /Execution_count Desc

-- 計算signal wait占整wait時間的百分比
-- 指令等待 CPU 資源的時間佔總時間的百分比。如果超過 25% ，說明 CPU 緊張
select convert(numeric(5,4),sum(signal_wait_time_ms)/sum(wait_time_ms)) 
from Sys.dm_os_wait_stats 

-- 計算'Cxpacket'占整wait時間的百分比
-- Cxpacket:Sql Server 在處理一句代價很大的語句，要不就是沒有合適的索引或篩選條件沒能篩選足夠的記錄，使得語句要返回大量的結果，當 >5% 說明有問題
declare @Cxpacket bigint
declare @Sumwaits bigint
select @Cxpacket = wait_time_ms
from Sys.dm_os_wait_stats
where wait_type = 'Cxpacket'
select @Sumwaits = sum(wait_time_ms)
from Sys.dm_os_wait_stats
select convert(numeric(5,4),@Cxpacket/@Sumwaits)


-- 查詢當前資料庫上所有使用者表格在Row lock上發生阻塞的頻率
declare @dbid int
select @dbid = db_id()
Select dbid=database_id, objectname=object_name(s.object_id)
, indexname=i.name, i.index_id    --, partition_number
, row_lock_count, row_lock_wait_count
, [block %]=cast (100.0 * row_lock_wait_count / (1 + row_lock_count) as numeric(15,2))
, row_lock_wait_in_ms
, [avg row lock waits in ms]=cast (1.0 * row_lock_wait_in_ms / (1 + row_lock_wait_count) as numeric(15,2))
from sys.dm_db_index_operational_stats (@dbid, NULL, NULL, NULL) s,     sys.indexes i
where objectproperty(s.object_id,'IsUserTable') = 1
and i.object_id = s.object_id
and i.index_id = s.index_id
order by row_lock_wait_count desc

--End Cpu 分析最佳化的相關 Sql 

 

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