Question

我正在运行来自NHibernate的查询并让我的探查器设置为跟踪任何慢速查询，有几个似乎在我的探查器中需要10秒以上：

exec sp_executesql N'SELECT top 50 this_.Debiteur_ID as Debiteur1_44_6_, this_.Debiteurnaam as Debiteur2_44_6_, this_.Debiteurnummer as Debiteur3_44_6_, this_.IsBedrijf_NeeJa as 
IsBedrijf4_44_6_, this_.Bedrijfsnaam as Bedrijfs5_44_6_, this_.Achternaam as Achternaam44_6_, this_.Tussenvoegsel as Tussenvo7_44_6_, this_.Voorletters as Voorlett8_44_6_, 
this_.Geboortedatum as Geboorte9_44_6_, this_.Titel_ID as Titel10_44_6_, this_.ManVrouw as ManVrouw44_6_, this_.Entiteit_ID as Entiteit12_44_6_, this_.Rechtsvorm_ID as Rechtsvorm13_44_6_, 
this_.Account_ID as Account14_44_6_, this_.Vestiging_Postcode as Vestiging15_44_6_, this_.Vestiging_Adres as Vestiging16_44_6_, this_.Vestiging_Plaats as Vestiging17_44_6_, 
this_.Vestiging_Huisnummer as Vestiging18_44_6_, this_.Vestiging_Land_ID as Vestiging19_44_6_, this_.Correspondentie_Postcode as Corresp20_44_6_, this_.Correspondentie_Adres as 
Corresp21_44_6_, this_.Correspondentie_Plaats as Corresp22_44_6_, this_.Correspondentie_Huisnummer as Corresp23_44_6_, this_.Correspondentie_Land_ID as Corresp24_44_6_, this_.Telefoonnummer as Telefoo25_44_6_, this_.Email as Email44_6_, this_.Mobiel as Mobiel44_6_, title3_.Titel_ID as Titel1_65_0_, title3_.Omschrijving as Omschrij2_65_0_, gender4_.Geslacht_ID as Geslacht1_30_1_, gender4_.Omschrijving as Omschrij2_30_1_, typeofcomp5_.Rechtsvorm_ID as Rechtsvorm1_8_2_, typeofcomp5_.Omschrijving as Omschrij2_8_2_, country6_.Land_ID as Land1_7_3_, country6_.Omschrijving as Omschrij2_7_3_, country6_.ISO as ISO7_3_, country6_.ISO_3166_a3 as ISO4_7_3_, country7_.Land_ID as Land1_7_4_, country7_.Omschrijving as Omschrij2_7_4_, country7_.ISO as ISO7_4_, country7_.ISO_3166_a3 as ISO4_7_4_, debtorreac1_.Debiteur_ID as Debiteur1_3_5_, debtorreac1_.DateOfOldestReaction as DateOfOl2_3_5_, debtorreac1_.TotalAmountOfReactions as TotalAmo3_3_5_, debtorreac1_.AmountOfResolvedReactions as AmountOf4_3_5_, debtorreac1_.AmountOfUnresolvedReactions as AmountOf5_3_5_, debtorreac1_.TotalOpenAmount as TotalOpe6_3_5_, debtorreac1_.UnresolvedOpenAmount as Unresolv7_3_5_, debtorreac1_.ResolvedOpenAmount as Resolved8_3_5_ FROM tbl_Debiteur this_ left outer join tbl_Titel title3_ on this_.Titel_ID=title3_.Titel_ID left outer join tbl_Geslacht gender4_ on this_.ManVrouw=gender4_.Geslacht_ID left outer join tbl_Rechtsvorm typeofcomp5_ on this_.Rechtsvorm_ID=typeofcomp5_.Rechtsvorm_ID left outer join tbl_Land country6_ on this_.Vestiging_Land_ID=country6_.Land_ID left outer join tbl_Land country7_ on this_.Correspondentie_Land_ID=country7_.Land_ID left outer join vw_DebtorReactionDetails debtorreac1_ on this_.Debiteur_ID=debtorreac1_.Debiteur_ID WHERE this_.Entiteit_ID = @p0 and debtorreac1_.AmountOfUnresolvedReactions > @p1 ORDER BY this_.Debiteur_ID asc',N'@p0 int,@p1 int',@p0=1104,@p1=0

当我运行完全相同的查询时，我就像这样粘贴在这里，所以包括参数和查询所需的一切都少于一秒。

我不知道为什么会这样，但现在的表现根本就不会有效。

问候。

Answer 1

自从我访问了这个话题以来，我们调整了一些查询，增加了一些索引，但更重要的是现在在更强大的服务器上运行。

这一切都说我相信我遇到的问题是参数嗅探之一：

http://www.simple-talk.com/sql/t-sql-programming/parameter-sniffing/

现在至少解决了这个问题。

Answer 2

您确定查询本身就是罪魁祸首吗？我很确定它不是执行查询的速度很慢，而是保护相应映射实体的过程，特别是在禁用延迟加载时考虑集合和/或多对一关联及其集合。

首先检查您的映射是否已设置了渴望获取，尝试设置

<property name="max_fetch_depth">1</property>

在你的NH配置中

只是为了限制自动急切提取（记得之后删除/更改值）

查询性能波动

2 个答案: