我的团队在使用 SQL Server 数据库时不断遇到性能问题。首先，该应用程序是用 Java 编写的并利用了 Hibernate。我们有一些数据存储在数据库中，我们可以轻松顺利地检索这些数据，以防我们想要选择完整的对象（例如：给定表中的所有或大部分字段）。
这很好用，但是当我们执行一个较小的查询时，它会慢 10 倍。最明显的部分可能是我们只检索一小部分字段（在此示例中：3）并使用其中带有 like 的 WHERE 子句（这在检索 84 个字段时似乎不是问题，但是当检索 3 个字段）。
Hibernate 完成简单查询大约需要 7 秒，而大查询大约需要 3.4 秒。在 DbVisualizer 中运行普通 SQL 时，复杂查询需要 0.02 秒的查询时间和 0.7 秒的数据传输时间。在 DbVisualizer 中运行的简单查询需要 0.2 秒（慢 10 倍），然后在大约 0.36 秒内传输（因此，要传输的数据更少）。有人可能会争辩说，这仍然比使用大查询更快，但它似乎对 Hibernate 性能有某种影响。
我开玩笑说“只需添加其他字段，直到该死的东西快速运行！”，但这并没有削减它，因为要选择的字段和 where 子句都将是用户配置的.
84 字段查询如下所示：
select
locateable0_.Un_ID as Un1_37_,
locateable0_.active as active37_,
locateable0_.code as code37_,
locateable0_.name as name37_,
locateable0_.ClientID as ClientID37_,
locateable0_.equipmentGroup as equipmen7_37_,
locateable0_.SupplierContractID as Supplier8_37_,
locateable0_.orderingCode as ordering9_37_,
locateable0_.expirationDate as expirat10_37_,
locateable0_.purchaseDate as purchas11_37_,
locateable0_.warrantyExpirationAlert as warrant12_37_,
locateable0_.price as price37_,
locateable0_.priceUnit as priceUnit37_,
locateable0_.VatID as VatID37_,
locateable0_.WEAlertJobID as WEAlert16_37_,
locateable0_.barcode as barcode37_,
locateable0_.erpCode as erpCode37_,
locateable0_.description as descrip19_37_,
locateable0_.innerWorksheet as innerWo20_37_,
locateable0_.outerWorksheet as outerWo21_37_,
locateable0_.ContractorCompanyID as Contrac22_37_,
locateable0_.ContractorPersonID as Contrac23_37_,
locateable0_.ManufacturerCompanyID as Manufac24_37_,
locateable0_.ManufacturerPersonID as Manufac25_37_,
locateable0_.ServicerCompanyID as Service26_37_,
locateable0_.ServicerPersonID as Service27_37_,
locateable0_.BudgetID as BudgetID37_,
locateable0_.costObjectId as costObj29_37_,
locateable0_.costKindId as costKindId37_,
locateable0_.TemplateId as TemplateId37_,
locateable0_.openingDate as opening32_37_,
locateable0_.mainClassId as mainCla33_37_,
locateable0_.pictureId as pictureId37_,
locateable0_.productType as product35_37_,
locateable0_.propertiesId as propert36_37_,
locateable0_.ParentID as ParentID37_,
locateable0_.accessDomainId as accessD38_37_,
locateable0_.orderStateType as orderSt39_37_,
locateable0_.orderEventId as orderEv40_37_,
locateable0_.locationId as locationId37_,
locateable0_.siteId as siteId37_,
locateable0_.buildingId as buildingId37_,
locateable0_.storeyId as storeyId37_,
locateable0_.roomId as roomId37_,
locateable0_.cadObjectId as cadObje46_37_,
locateable0_.geoLattitude as geoLatt47_37_,
locateable0_.geoLongitude as geoLong48_37_,
locateable0_.ratingId as ratingId37_,
locateable0_.grossArea as grossArea37_,
locateable0_.grossVolume as grossVo51_37_,
locateable0_1_.floor as floor99_,
locateable0_2_.calculatedArea as calculat2_100_,
locateable0_2_.nominalArea as nominalA3_100_,
locateable0_2_.categoryId as categoryId100_,
locateable0_2_.wingId as wingId100_,
locateable0_2_.areaUnitId as areaUnitId100_,
locateable0_2_.cleaningArea as cleaning7_100_,
locateable0_2_.rentableArea as rentable8_100_,
locateable0_2_.windowSurface as windowSu9_100_,
locateable0_2_.bottomSurface as bottomS10_100_,
locateable0_2_.topSurface as topSurface100_,
locateable0_2_.wallSurface as wallSur12_100_,
locateable0_2_.floorType as floorType100_,
locateable0_3_.areaSize as areaSize101_,
locateable0_3_.areaType as areaType101_,
locateable0_3_.flooring as flooring101_,
locateable0_4_.workplaceNumber as workplac2_102_,
locateable0_4_.workplaceType as workplac3_102_,
locateable0_4_.usingCompanyId as usingCom4_102_,
locateable0_5_.quantity as quantity190_,
locateable0_5_.quantityUnitId as quantity3_190_,
locateable0_6_.inventoryNumber as inventor2_202_,
locateable0_7_.area as area233_,
locateable0_7_.meterValue as meterValue233_,
locateable0_7_.calibrationFactor as calibrat4_233_,
locateable0_7_.areaDomainId as areaDoma5_233_,
locateable0_7_.degreeDayId as degreeDa6_233_,
locateable0_7_.virtualType as virtualT7_233_,
locateable0_7_.differenceFactor as differen8_233_,
locateable0_7_.differenceMasterId as differen9_233_,
locateable0_7_.virtual as virtual233_,
locateable0_7_.startDate as startDate233_,
locateable0_7_.scheduleId as scheduleId233_,
locateable0_.discriminator as discrimi2_37_
from
MNT_Equipments locateable0_
left outer join
Storey locateable0_1_
on locateable0_.Un_ID=locateable0_1_.id
left outer join
Room locateable0_2_
on locateable0_.Un_ID=locateable0_2_.id
left outer join
RoomArea locateable0_3_
on locateable0_.Un_ID=locateable0_3_.id
left outer join
Workplace locateable0_4_
on locateable0_.Un_ID=locateable0_4_.id
left outer join
INV_Product locateable0_5_
on locateable0_.Un_ID=locateable0_5_.id
left outer join
MNT_FacilityProduct locateable0_6_
on locateable0_.Un_ID=locateable0_6_.id
left outer join
EN_ResourceMeter locateable0_7_
on locateable0_.Un_ID=locateable0_7_.id
left outer join
DynamicProperties dynamicpro1_
on locateable0_.propertiesId=dynamicpro1_.id
left outer join
KEYWORDSEARCH tags2_
on dynamicpro1_.id=tags2_.dynamicPropertiesId
left outer join
MNT_Clients client3_
on locateable0_.ClientID=client3_.Un_ID
where
(
locateable0_.accessDomainId is null
or locateable0_.accessDomainId in (
select
uad.domainId
from
PERM_UserAccessDomain uad
join
Users u
on uad.userId = u.Un_ID
where
u.UserName = 'wsc'
and uad.functionId = 2000
)
)
and locateable0_.discriminator in (
'17000', '6010', '6020', '6030', '6035', '6040', '6060', '6070', '6080', '18000', '5010', '6000', '6100', '5000', '9000', '14000', '19000'
)
and (
client3_.Un_ID in (
1012, 1016, 1013, 1014
)
)
and (
locateable0_.productType not in (
18000, 19000
)
)
and locateable0_.active=1
and locateable0_.productType<>6080
and (
upper(tags2_.keyword) like 'B%'
)
慢速 3-field-query 如下所示：
select
locateable0_.Un_ID as col_0_0_,
locateable0_.code as col_1_0_,
locateable0_.name as col_2_0_
from
MNT_Equipments locateable0_
left outer join
DynamicProperties dynamicpro1_
on locateable0_.propertiesId=dynamicpro1_.id
left outer join
KEYWORDSEARCH tags2_
on dynamicpro1_.id=tags2_.dynamicPropertiesId
left outer join
MNT_Clients client3_
on locateable0_.ClientID=client3_.Un_ID
where
(
locateable0_.accessDomainId is null
or locateable0_.accessDomainId in (
select
uad.domainId
from
PERM_UserAccessDomain uad
join
Users u
on uad.userId = u.Un_ID
where
u.UserName = 'wsc'
and uad.functionId = 2000
)
)
and locateable0_.discriminator in (
'17000', '6010', '6020', '6030', '6035', '6040', '6060', '6070', '6080', '18000', '5010', '6000', '6100', '5000', '9000', '14000', '19000'
)
and (
client3_.Un_ID in (
1012, 1016, 1013, 1014
)
)
and (
locateable0_.productType not in (
18000, 19000
)
)
and locateable0_.active=1
and (
upper(tags2_.keyword) like 'B%'
)
Microsoft SQL Server Management Studio 建议为我们请求的字段添加索引，但这样做根本没有帮助。特别是要记住要查询的字段将是用户可配置的，并且休眠将在查询和获取所需的时间之上增加巨大的好处。
那么，我们可以做些什么来将性能提高到可接受的水平呢？