Question

我在sql server 2012上运行以下更新命令。

update a
set a.proc_flag='CC'
from abc.dbo.table1 a with (NOLOCK)
inner join xyz.dbo.table2 b with (NOLOCK)
on a.id = b.id
where a.proc_flag ='C'
and b.dt >= dateadd(D,-(180),cast(GETDATE() as date))
and b.position in 
(
'AD',
'BUE',
'DS',
'HP',
'IFER',
'MER',
'NT',
'NNG',
'TON',
'GNUM',
'ERNA',
'BL', 
'DPO', 
'DEM', 
'HU',
'ILL',
'IKT',
'LB',
'OM',
'GE',
'RF',
'sd',
'avb');

table1包含大约1百万的记录，而table2包含数百万（大表）。每次运行查询时，它都会从 dm_exec_requests 等待类型显示 cxpacket 进入暂停模式，所以我使用 maxdop 1 暗示不使用并行性。

之后我得到 PAGEIOLATCH_SH 等待类型。我打开活动监视器，看看那里发生了什么。所以它显示我的缓冲存储器已满13 GB（我机器的RAM仅为15 GB）。

所以请告诉我，我是否必须优化查询，否则我需要其他东西。

编辑：table2上的索引

1-    CREATE NONCLUSTERED INDEX [IDX_DT] ON [dbo].[table2]
(
    [dt] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, SORT_IN_TEMPDB = OFF, DROP_EXISTING = OFF, ONLINE = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
GO

2 - CREATE NONCLUSTERED INDEX [IDX_SERVER_DT] ON [dbo].[table2]
    (
        [server_id] ASC,
        [dt] ASC
    )WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, SORT_IN_TEMPDB = OFF, DROP_EXISTING = OFF, ONLINE = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
    GO

表1上的

索引

CREATE NONCLUSTERED INDEX [ID] ON [dbo].[table1]
(
    [ID] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, SORT_IN_TEMPDB = OFF, DROP_EXISTING = OFF, ONLINE = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
GO

编辑2：

这是我在查询执行计划中得到的：

 StmtText   StmtId  NodeId  Parent  PhysicalOp  LogicalOp   Argument    DefinedValues   EstimateRows    EstimateIO  EstimateCPU AvgRowSize  TotalSubtreeCost    OutputList  Warnings    Type    Parallel    EstimateExecutions
update a
set a.proc_flag='CF'
from abc.dbo.table1 a with (NOLOCK)
inner join xyz.dbo.table2 b with (NOLOCK)
on a.id = b.id
where a.proc_flag ='C'
and b.dt >= dateadd(D,-(cast('180' as int)),cast(GETDATE() as date))
and b.position in 
(
'ADC',
'BUSINE',
'DNC',
'HUNGUP',
'INXFER',
'MNXFER',
'NCOMIT',
'NONENG',
'TRITON',
'WRGNUM',
'XFERNA',
'BL', 
'DISPO', 
'DONEM', 
'HU',
'INCALL',
'INKT',
'LB',
'NONCOM',
'PLEDGE',
'REF',
'SALE',
'XFER') 1   1   0   NULL    NULL    1   NULL    1   NULL    NULL    NULL    0.03451508  NULL    NULL    UPDATE  0   NULL
  |--Table Update(OBJECT:([abc].[dbo].[table1] AS [a]), SET:([abc].[dbo].[table1].[proc_flag] as [a].[proc_flag] = [Expr1006])) 1   2   1   Table Update    Update  OBJECT:([abc].[dbo].[table1] AS [a]), SET:([abc].[dbo].[table1].[proc_flag] as [a].[proc_flag] = [Expr1006])    NULL    1   0.01    1E-06   9   0.03451508  NULL    NULL    PLAN_ROW    0   1
       |--Compute Scalar(DEFINE:([Expr1006]='CF'))  1   3   2   Compute Scalar  Compute Scalar  DEFINE:([Expr1006]='CF')    [Expr1006]='CF' 1   0   1E-07   20  0.02451408  [Bmk1000], [Expr1006]   NULL    PLAN_ROW    0   1
            |--Top(ROWCOUNT est 0)  1   4   3   Top Top TOP EXPRESSION:((0))    NULL    1   0   1E-07   15  0.02451398  [Bmk1000]   NULL    PLAN_ROW    0   1
                 |--Sort(DISTINCT ORDER BY:([Bmk1000] ASC)) 1   5   4   Sort    Distinct Sort   DISTINCT ORDER BY:([Bmk1000] ASC)   NULL    1   0.01126126  0.000100015 15  0.02451388  [Bmk1000]   NULL    PLAN_ROW    0   1
                      |--Nested Loops(Inner Join, OUTER REFERENCES:([Bmk1000])) 1   6   5   Nested Loops    Inner Join  OUTER REFERENCES:([Bmk1000])    NULL    1   0   4.18E-06    20  0.01315212  [Bmk1000]   NULL    PLAN_ROW    0   1
                           |--Nested Loops(Inner Join, OUTER REFERENCES:([b].[id])) 1   7   6   Nested Loops    Inner Join  OUTER REFERENCES:([b].[id]) NULL    1   0   4.18E-06    15  0.00986484  [Bmk1000]   NULL    PLAN_ROW    0   1
                           |    |--Filter(WHERE:([xyz].[dbo].[table2].[position] as [b].[position]='ADC' OR [xyz].[dbo].[table2].[position] as [b].[position]='BL' OR [xyz].[dbo].[table2].[position] as [b].[position]='BUSINE' OR [xyz].[dbo].[table2].[position] as [b].[position]='DISPO' OR [xyz].[dbo].[table2].[position] as [b].[position]='DNC' OR [xyz].[dbo].[table2].[position] as [b].[position]='DONEM' OR [xyz].[dbo].[table2].[position] as [b].[position]='HU' OR [xyz].[dbo].[table2].[position] as [b].[position]='HUNGUP' OR [xyz].[dbo].[table2].[position] as [b].[position]='INCALL' OR [xyz].[dbo].[table2].[position] as [b].[position]='INKT' OR [xyz].[dbo].[table2].[position] as [b].[position]='INXFER' OR [xyz].[dbo].[table2].[position] as [b].[position]='LB' OR [xyz].[dbo].[table2].[position] as [b].[position]='MNXFER' OR [xyz].[dbo].[table2].[position] as [b].[position]='NCOMIT' OR [xyz].[dbo].[table2].[position] as [b].[position]='NONCOM' OR [xyz].[dbo].[table2].[position] as [b].[position]='NONENG' OR [xyz].[dbo].[table2].[position] as [b].[position]='PLEDGE' OR [xyz].[dbo].[table2].[position] as [b].[position]='REF' OR [xyz].[dbo].[table2].[position] as [b].[position]='SALE' OR [xyz].[dbo].[table2].[position] as [b].[position]='TRITON' OR [xyz].[dbo].[table2].[position] as [b].[position]='WRGNUM' OR [xyz].[dbo].[table2].[position] as [b].[position]='XFER' OR [xyz].[dbo].[table2].[position] as [b].[position]='XFERNA'))    1   8   7   Filter  Filter  WHERE:([xyz].[dbo].[table2].[position] as [b].[position]='ADC' OR [xyz].[dbo].[table2].[position] as [b].[position]='BL' OR [xyz].[dbo].[table2].[position] as [b].[position]='BUSINE' OR [xyz].[dbo].[table2].[position] as [b].[position]='DISPO' OR [xyz].[dbo].[table2].[position] as [b].[position]='DNC' OR [xyz].[dbo].[table2].[position] as [b].[position]='DONEM' OR [xyz].[dbo].[table2].[position] as [b].[position]='HU' OR [xyz].[dbo].[table2].[position] as [b].[position]='HUNGUP' OR [xyz].[dbo].[table2].[position] as [b].[position]='INCALL' OR [xyz].[dbo].[table2].[position] as [b].[position]='INKT' OR [xyz].[dbo].[table2].[position] as [b].[position]='INXFER' OR [xyz].[dbo].[table2].[position] as [b].[position]='LB' OR [xyz].[dbo].[table2].[position] as [b].[position]='MNXFER' OR [xyz].[dbo].[table2].[position] as [b].[position]='NCOMIT' OR [xyz].[dbo].[table2].[position] as [b].[position]='NONCOM' OR [xyz].[dbo].[table2].[position] as [b].[position]='NONENG' OR [xyz].[dbo].[table2].[position] as [b].[position]='PLEDGE' OR [xyz].[dbo].[table2].[position] as [b].[position]='REF' OR [xyz].[dbo].[table2].[position] as [b].[position]='SALE' OR [xyz].[dbo].[table2].[position] as [b].[position]='TRITON' OR [xyz].[dbo].[table2].[position] as [b].[position]='WRGNUM' OR [xyz].[dbo].[table2].[position] as [b].[position]='XFER' OR [xyz].[dbo].[table2].[position] as [b].[position]='XFERNA')   NULL    1   0   7.18E-06    20  0.00657756  [b].[id]    NULL    PLAN_ROW    0   1
                           |    |    |--Nested Loops(Inner Join, OUTER REFERENCES:([Bmk1003]) OPTIMIZED)    1   9   8   Nested Loops    Inner Join  OUTER REFERENCES:([Bmk1003]) OPTIMIZED  NULL    1   0   4.18E-06    24  0.00657038  [b].[id], [b].[position]    NULL    PLAN_ROW    0   1
                           |    |         |--Compute Scalar(DEFINE:([Expr1018]=BmkToPage([Bmk1003])))   1   11  9   Compute Scalar  Compute Scalar  DEFINE:([Expr1018]=BmkToPage([Bmk1003]))    [Expr1018]=BmkToPage([Bmk1003]) 1   0.003125    0.0001581   15  0.0032831   [Bmk1003], [Expr1018]   NULL    PLAN_ROW    0   1
                           |    |         |    |--Nested Loops(Inner Join, OUTER REFERENCES:([Expr1016], [Expr1017], [Expr1015]))   1   12  11  Nested Loops    Inner Join  OUTER REFERENCES:([Expr1016], [Expr1017], [Expr1015])   NULL    1   0.003125    0.0001581   15  0.0032831   [Bmk1003]   NULL    PLAN_ROW    0   1
                           |    |         |         |--Compute Scalar(DEFINE:(([Expr1016],[Expr1017],[Expr1015])=GetRangeWithMismatchedTypes(dateadd(day,(-180),CONVERT(date,getdate(),0)),NULL,(22)))) 1   13  12  Compute Scalar  Compute Scalar  DEFINE:(([Expr1016],[Expr1017],[Expr1015])=GetRangeWithMismatchedTypes(dateadd(day,(-180),CONVERT(date,getdate(),0)),NULL,(22)))    ([Expr1016],[Expr1017],[Expr1015])=GetRangeWithMismatchedTypes(dateadd(day,(-180),CONVERT(date,getdate(),0)),NULL,(22)) 1   0   0   27  0   [Expr1016], [Expr1017], [Expr1015]  NULL    PLAN_ROW    0   1
                           |    |         |         |    |--Constant Scan   1   14  13  Constant Scan   Constant Scan   NULL    NULL    1   0   0   0   0   NULL    NULL    PLAN_ROW    0   1
                           |    |         |         |--Index Seek(OBJECT:([xyz].[dbo].[table2].[IDX_DTANSWERED] AS [b]), SEEK:([b].[dt] > [Expr1016] AND [b].[dt] < [Expr1017]) ORDERED FORWARD)    1   18  12  Index Seek  Index Seek  OBJECT:([xyz].[dbo].[table2].[IDX_DTANSWERED] AS [b]), SEEK:([b].[dt] > [Expr1016] AND [b].[dt] < [Expr1017]) ORDERED FORWARD   [Bmk1003]   1   0.003125    0.0001581   15  0.0032831   [Bmk1003]   NULL    PLAN_ROW    0   1
                           |    |         |--RID Lookup(OBJECT:([xyz].[dbo].[table2] AS [b]), SEEK:([Bmk1003]=[Bmk1003]) LOOKUP ORDERED FORWARD)    1   23  9   RID Lookup  RID Lookup  OBJECT:([xyz].[dbo].[table2] AS [b]), SEEK:([Bmk1003]=[Bmk1003]) LOOKUP ORDERED FORWARD [b].[id], [b].[position]    1   0.003125    0.0001581   28  0.0032831   [b].[id], [b].[position]    NULL    PLAN_ROW    0   1
                           |    |--Index Seek(OBJECT:([abc].[dbo].[table1].[IDX_PHONE] AS [a]), SEEK:([a].[id]=[xyz].[dbo].[table2].[id] as [b].[id]) ORDERED FORWARD)  1   30  7   Index Seek  Index Seek  OBJECT:([abc].[dbo].[table1].[IDX_PHONE] AS [a]), SEEK:([a].[id]=[xyz].[dbo].[table2].[id] as [b].[id]) ORDERED FORWARD [Bmk1000]   1   0.003125    0.0001581   15  0.0032831   [Bmk1000]   NULL    PLAN_ROW    0   1
                           |--RID Lookup(OBJECT:([abc].[dbo].[table1] AS [a]), SEEK:([Bmk1000]=[Bmk1000]),  WHERE:([abc].[dbo].[table1].[proc_flag] as [a].[proc_flag]='C') LOOKUP ORDERED FORWARD) 1   32  6   RID Lookup  RID Lookup  OBJECT:([abc].[dbo].[table1] AS [a]), SEEK:([Bmk1000]=[Bmk1000]),  WHERE:([abc].[dbo].[table1].[proc_flag] as [a].[proc_flag]='C') LOOKUP ORDERED FORWARD   NULL    1   0.003125    0.0001581   12  0.0032831   NULL    NULL    PLAN_ROW    0   1

修改：3

在进行大量搜索后，我还要添加一件事。我发现一些查询给了我以下输出，为什么上面的查询进入暂停模式，因为 pageiolatch_sh

Object  Type       Index       Index_Type   buffer_pages     buffer_mb
TABLE2  USER_TABLE             HEAP         1319249      10306

Answer 1

您没有告诉我们该查询是否在合理的时间跨度内完成如果是这种情况，那么你不应该修改它（阅读关于premature optimization ^^的许多文章之一）。

第一个改进是表2中的index on the foreign key;处理数百万行，其中一个链接字段未编入索引。你评估了这样一个索引对你的申请的影响吗？是否可以在系统上创建该索引而不影响日常操作？

根据应用的WHERE过滤器产生的行数，您可以尝试使用子查询：

update a
set a.proc_flag='CC'
from abc.dbo.table1 a with (NOLOCK)
inner join (
  select [only the fields you need] from xyz.dbo.table2 
  dt >= dateadd(D,-(180),cast(GETDATE() as date))
  and position in ('AD',...,'avb')
) b on a.id = b.id
where a.proc_flag ='C';

如果过滤器大大减少了table2的行数，这个解决方案可能会有所改进对于table1也是如此;如果proc_flag上的过滤器排除将过滤器移动到子查询中的一半行可能会有一些改进以上只是猜测，因为query optimizer，但变化是如此之小，可能值得一试...

查询在sql server中占用太多时间

1 个答案: