Sql 数据检索性能

使用SSMS或Azure data Studio，我可以在2毫秒内将50万行插入临时表，但从临时表或临时表中检索要筛选的行需要13到15秒。我不确定下一步该去哪里寻找性能损失的地方，因为这不是几个月前发布的问题

这是一台生产服务器，从SQL 2017开始已经运行了几个月。无论我是在客户机上还是直接在服务器上，都会发生这种情况，但是在一台带有标准磁盘的基本PC上&只有8gig的RAM，速度快了三倍

SELECT SML.CONTACT_Id
INTO ##slr
FROM dbo.Stage_MailingLists AS SML;

SELECT *
FROM ##slr AS S;

DROP TABLE ##slr;

SQL Server parse and compile time: 
   CPU time = 0 ms, elapsed time = 0 ms.

 SQL Server Execution Times:
   CPU time = 0 ms,  elapsed time = 0 ms.
SQL Server parse and compile time: 
   CPU time = 0 ms, elapsed time = 2 ms.
Table 'Stage_MailingLists'. Scan count 9, logical reads 13482, physical reads 0, read-ahead reads 0, lob logical reads 0, lob physical reads 0, lob read-ahead reads 0.

(521001 rows affected)

(1 row affected)

 SQL Server Execution Times:
   CPU time = 1187 ms,  elapsed time = 365 ms.
SQL Server parse and compile time: 
   CPU time = 0 ms, elapsed time = 0 ms.

(521001 rows affected)
Table '##slr'. Scan count 1, logical reads 1493, physical reads 0, read-ahead reads 0, lob logical reads 0, lob physical reads 0, lob read-ahead reads 0.

(1 row affected)

 SQL Server Execution Times:
   CPU time = 329 ms,  elapsed time = 8296 ms.
SQL Server parse and compile time: 
   CPU time = 0 ms, elapsed time = 0 ms.

 SQL Server Execution Times:
   CPU time = 0 ms,  elapsed time = 0 ms.

---

插入数据和显示数据是非常不同的。当您执行

插入时

不会将任何数据返回到客户机，所有内容都包含在实例中。应用程序也不需要解释返回的数据集并将其转换为显示

当您使用

选择

以显示数据时，需要将该数据从实例发送到客户端；如果该客户机是远程主机，那么网络速度/流量等因素可能是大型数据集的一个重要因素（这里有50万行，这是一个相当可观的显示量）。应用程序还需要解释来自实例的数据，并将其转换为可显示的格式；在SSM中，可能正在将其转换为数据网格。如果您正在限制客户端，那么也可能会减慢查询速度，因为数据需要加载到应用程序的内存池中并进行处理以显示

---

选择

和

插入

的速度，特别是对于大型数据集，可能无法与之相比，因为有着完全不同的操作。

结果是，Sophos antivirus有一个更新“挂起重启”，导致服务器重启瓶颈，并全部返回到预期基线。

因为您使用的是SQL 2017，您可以使用会话等待统计信息来测量引擎等待查询的时间。例如，在Master中安装一个程序，如：

use master
go
create or alter procedure sp_exec_with_time_and_wait_stats @sql nvarchar(max)
as
begin

set nocount on;

with q as
(
    select *
    from sys.dm_exec_session_wait_stats
    where session_id = @@spid
    union all
    select @@spid session_id, 'CPU_TIME', 0,cpu wait_time_ms,0,0
    from sysprocesses where spid = @@spid 
)
select *
into #waits
from q 

print ('-------begin batch--------')
print ( @sql )
print ('--------end batch---------')
set statistics io on;
set statistics time on;
exec ( @sql );
set statistics io off;
set statistics time off;

declare c cursor local for
with n as
(
    select *
    from sys.dm_exec_session_wait_stats
    where session_id = @@spid
    union all
    select @@spid session_id, 'CPU_TIME', 0,cpu cpu_time,0,0
    from sysprocesses where spid = @@spid 
)
select n.wait_type, 
       n.waiting_tasks_count - coalesce(p.waiting_tasks_count,0) waiting_tasks_count,
       n.wait_time_ms - coalesce(p.wait_time_ms,0) wait_time_ms,
       case when n.max_wait_time_ms > coalesce(p.max_wait_time_ms,0) then n.max_wait_time_ms else null end max_wait_time,
       n.signal_wait_time_ms - coalesce(p.signal_wait_time_ms,0) signal_wait_time
from n
left join #waits p
  on p.wait_type = n.wait_type
where n.session_id = @@spid
and n.wait_time_ms > coalesce(p.wait_time_ms,0)
order by n.wait_time_ms - coalesce(p.wait_time_ms,0)  desc;

declare @wait_type nvarchar(60),
        @waiting_tasks_count bigint,
        @wait_time_ms bigint,
        @max_wait_time_ms bigint,
        @signal_wait_time_ms bigint
print (
'
SQL Server Wait Times (with CPU):

  wait_type                                                    waiting_tasks_count  wait_time_ms          max_wait_time      signal_wait_time')
print (
'  ------------------------------------------------------------ -------------------- --------------------- ------------------ --------------------')

open c
fetch next from c into @wait_type,  @waiting_tasks_count,  @wait_time_ms,  @max_wait_time_ms,  @signal_wait_time_ms
while @@FETCH_STATUS = 0
begin

  declare @line nvarchar(2000) = N''
  declare @val nvarchar(60) = @wait_type
  declare @len int = 45

  set @line = concat(@line,left(concat(@val, space(@len)),@len))

  set @len = 20
  set @val = str(@waiting_tasks_count)
  set @line = concat(@line,right(concat(space(@len),@val),@len))

  set @val = str(@wait_time_ms)
  set @line = concat(@line,right(concat(space(@len),@val),@len))

  set @val = str(coalesce(@max_wait_time_ms,''))
  set @line = concat(@line,right(concat(space(@len),@val),@len))

  set @val = str(@signal_wait_time_ms)
  set @line = concat(@line,right(concat(space(@len),@val),@len))


  print ('  ' + @line)
  fetch next from c into @wait_type,  @waiting_tasks_count,  @wait_time_ms,  @max_wait_time_ms,  @signal_wait_time_ms
end
close c
deallocate c
print ('')

end

然后从您的数据库

use AdventureWorksDW2017
go
declare @sql nvarchar(max) = 'select top 1000000 *  into #x from factInternetSales order by 1,2,5;'
exec sp_exec_with_time_and_wait_stats @sql

它将打印您的IO、CPU和等待状态，如：

-------begin batch--------
select top 1000000 *  into #x from factInternetSales order by 1,2,5;
--------end batch---------
SQL Server parse and compile time: 
   CPU time = 0 ms, elapsed time = 12 ms.
Table 'FactInternetSales'. Scan count 9, logical reads 1260, physical reads 0, read-ahead reads 1260, lob logical reads 0, lob physical reads 0, lob read-ahead reads 0.
Table 'Worktable'. Scan count 0, logical reads 0, physical reads 0, read-ahead reads 0, lob logical reads 0, lob physical reads 0, lob read-ahead reads 0.
Table 'Worktable'. Scan count 0, logical reads 0, physical reads 0, read-ahead reads 1057, lob logical reads 0, lob physical reads 0, lob read-ahead reads 0.

 SQL Server Execution Times:
   CPU time = 435 ms,  elapsed time = 335 ms.

 SQL Server Execution Times:
   CPU time = 435 ms,  elapsed time = 349 ms.

 SQL Server Execution Times:
   CPU time = 0 ms,  elapsed time = 0 ms.

SQL Server Wait Times (with CPU):

  wait_type                                                    waiting_tasks_count  wait_time_ms          max_wait_time      signal_wait_time
  ------------------------------------------------------------ -------------------- --------------------- ------------------ --------------------
  LATCH_EX                                                     4879                 572                   0                  69
  CPU_TIME                                                        0                 435                   0                   0
  CXPACKET                                                       22                 331                   0                   0
  PAGEIOLATCH_SH                                                 26                  10                   0                   0
  PAGELATCH_SH                                                   17                   6                   0                   1
  PAGELATCH_UP                                                   74                   6                   0                   1
  LCK_M_S                                                         9                   3                   0                   0
  CXROWSET_SYNC                                                   8                   2                   0                   0
  MEMORY_ALLOCATION_EXT                                         601                   1                   0                   0
  SESSION_WAIT_STATS_CHILDREN                                    11                   1                   0                   1
  LATCH_SH                                                        3                   1                   0                   0

---

你好感谢您的回复我理解，我试图证明服务器功能正常等，问题是检索方面出现了前所未有的大幅下降，我不知道要测试什么/基准点，即是否与SAN相关等，但如果数据是RAM，SAN为什么会成为问题，因此，网络，但为什么它直接在服务器上和在客户端上是一样的。“在基本pc上…”最有可能的意思是“在没有其他活动的pc上”。苹果与橙子的比较。它还省略了通过网络发送结果集所需的时间。组织外部的任何人都无法提供有用的信息。而等待数月的讨论只会增加查找原因的难度（假设它不是纯粹基于资源争用）。你的出发点应该是询问你的dba。将数据移出数据库是一个相当昂贵的操作——就像在某些设备上显示数据一样。嗨，我问过dba他和我一样困惑，我在工作时间之外做了测试，所以负载接近于零。我已经使用SQL多年了，我知道您提出的问题是，性能大幅下降，但没有升级/更改。这只是一个例子，看看人们是否可以给我任何选择来尝试，我有一个服务器上运行缓慢的查询负载，该服务器整天的空闲时间不到10%的CPU，使用该服务器运行速度很快，但突然大大降低，慢了3到5倍。