我的查询有这个问题,它确实很慢。我正在使用MSSQL server 2008并且有3个数据库,里面有数百个样本数据。查询将返回基于3个DB的名称和值以及计算的百分比。但是我的查询将花费大约10分钟来执行,这真的需要很长时间。我仍在学习SQL,但仍然不那么好,所以我认为我的查询不是使用最佳实践而且没有组织。任何人都能指出我在哪里或如何改进我的查询以更快地运行?
SELECT data.Ret,
case
when @group_by= 'site' OR (@group_by='attribute' AND @attribute_id = '5') and (data.rowid % 50) = 0 then (data.rowid / 50)-1
when @group_by= 'site' OR (@group_by='attribute' AND @attribute_id = '5') then (data.rowid / 50)
else 0 end as batchStore
,data.MajorName,data.MinorName,data.MajorVal,data.MinorVal,data.Version
,data.A_Percent,data.T_Percent,data.F_Percent
from
(
SELECT report.Ret,
CASE when @group_by= 'site' OR (@group_by='attribute' AND @attribute_id = '5')
then row_number() over (PARTITION BY report.Ret,report.Version order by report.Ret, report.MajorName)
else 0 end as rowid
,report.MajorName,report.MinorName,report.MajorVal,report.MinorVal,report.Version
,report.GTotal_A,report.GTotal_T,report.GTotal_F
,ISNULL(sum(report.Abn) / NULLIF(cast(report.GTotal_A as decimal),0),0) * 100 as A_Percent
,ISNULL(sum(report.Trn) / NULLIF(cast(report.GTotal_T as decimal),0),0) * 100 as T_Percent
,ISNULL(sum(report.Fld)/ NULLIF(cast(report.GTotal_F as decimal),0) * 100,0) as F_Percent
From
(
Select
CASE @group_by
WHEN 'object' THEN csl.s_name
WHEN 'site' THEN csl.s_name
WHEN 'year' THEN CAST(YEAR(dy.Day_Stamp) AS VARCHAR(50))
WHEN 'attribute' THEN CAST(coalesce(attrib.AttributeName,'') AS VARCHAR(50))
ELSE ''
END as MajorName,
CASE @group_by
WHEN 'object' THEN l.l_name
WHEN 'site' THEN ''
WHEN 'attribute' THEN CAST(coalesce(attrib.AttributeName,'') AS VARCHAR(50))
ELSE ''
END as MinorName,
CASE @group_by
WHEN 'object' THEN csl.s_name
WHEN 'site' THEN csl.s_name
WHEN 'year' THEN CAST(YEAR(dy.Day_Stamp) AS VARCHAR(50))
WHEN 'attribute' THEN CAST(coalesce(attrib.AttributeValue,'') AS VARCHAR(50))
ELSE ''
END as MajorVal,
CASE @group_by
WHEN 'object' THEN l.l_name
WHEN 'site' THEN ''
WHEN 'attribute' THEN CAST(coalesce(attrib.AttributeValue,'') AS VARCHAR(50))
ELSE ''
END as MinorVal,
csl.Cust_Name as Ret,l.SWVersion as Version
,d.Abn,d.Trn,d.Fld,data.GTotal_A ,data.GTotal_T,data.GTotal_F
From db_mon.dbo.CustSL csl
join db_tax.dbo.vwLane l
on (l.externalid = csl.custsl_id)
join db_mon.dbo.DaySummary dy
on (dy.Str = csl.s_name and dy.Lne = csl.l_name and year(dy.day_stamp) = year(@time_start_date) and year(dy.day_stamp) =year(@time_end_date))
Left Outer Join
(
Select a.id As AttributeId, a.attribute_name As AttributeName,
(Case When a.attribute_value_type = 'string' Then ea.string_value
Else (Case When a.attribute_value_type = 'integer' Then cast(ea.integer_value as nvarchar(100))
Else (Case When a.attribute_value_type = 'date' Then cast(ea.date_value as nvarchar(100))
Else (Case When a.attribute_value_type = 'boolean' Then cast(ea.boolean_value as nvarchar(100))
Else (Case When a.attribute_value_type = 'entity' Then cast(ea.ref_entity_id as nvarchar(100)) Else null End)
End)
End)
End)
End) As AttributeValue,
e.id As EntityId
From db_tax.dbo.entity_type et
Inner Join db_tax.dbo.entity As e on et.id = e.entity_type_id
Inner Join db_tax.dbo.entity_attribute As ea on e.id = ea.entity_id
Inner Join db_tax.dbo.attribute As a on ea.attribute_id = a.id
WHERE et.entity_type_name in ('Sticker','Label') And
a.id = (case WHEN @attribute_id = '' then 1 else cast(@attribute_id as int) end)
) AS attrib
On attrib.EntityId = l.L_Id
inner join db_mon.dbo.DaySummary d
on (csl.Cust_Name = d.Ret and csl.s_name = d.stckr and csl.l_name = d.label and l.SWVersion = d.Version)
join (
SELECT Ret,version,sum(Abn) as GTotal_A,sum(Trn) as GTotal_T,sum(Fld) as GTotal_F
from db_mon.dbo.DaySummary
where day_stamp >= @time_start_date and day_stamp <=@time_end_date
GROUP BY Ret,version
) data
on (d.Ret = data.Ret and l.SWVersion = data.Version)
WHERE (CHARINDEX(',' + CONVERT(VARCHAR,l.S_Id) + ',','xxx,' + @entities + ',xxx')>0 OR CHARINDEX(',' + CONVERT(VARCHAR,l.L_Id) + ',','xxx,' + @entities + ',xxx')>0)
and d.day_stamp >= @time_start_date
and d.day_stamp <=@time_end_date
) As report
Group By report.Ret,report.Version,report.MajorName,report.MinorName,report.MajorVal,report.MinorVal
,report.GTotal_A,report.GTotal_T,report.GTotal_F
)data
order By data.Ret,data.Version,batchStore,data.MajorName,data.MinorName,data.MajorVal,data.MinorVal
使用大量连接会导致执行缓慢吗?
答案 0 :(得分:0)
SUB Select查询总是慢于正确的连接。
您正在深入运行3个子选择。无论指标如何变化,这都会影响您的表现。
你需要重写整个事情以停止使用子选择。