我有一个函数可以将 3 行写入一个空表,如下所示:
INSERT [dbo].[yaf_ForumAccess] ([GroupID], [ForumID], [AccessMaskID]) VALUES (1, 8, 1)
INSERT [dbo].[yaf_ForumAccess] ([GroupID], [ForumID], [AccessMaskID]) VALUES (2, 8, 4)
INSERT [dbo].[yaf_ForumAccess] ([GroupID], [ForumID], [AccessMaskID]) VALUES (3, 8, 3)
出于某种原因,只有第三个查询需要很长时间才能执行 - 并且随着每次插入,它会变得更长。
Profiler Image http://www.cricut.com/images/SqlQuery.png Profiler Image
我尝试禁用表上的所有约束 - 结果相同。我只是不明白为什么前两个会跑得这么快——而最后一个会花这么长时间。
如有任何帮助,我们将不胜感激。
这是运行 MSSMS 的查询的统计信息:
查询:
ALTER TABLE [dbo].[yaf_ForumAccess] NOCHECK CONSTRAINT ALL
INSERT [dbo].[yaf_ForumAccess] ([GroupID], [ForumID], [AccessMaskID]) VALUES (1, 9, 1)
INSERT [dbo].[yaf_ForumAccess] ([GroupID], [ForumID], [AccessMaskID]) VALUES (2, 9, 4)
INSERT [dbo].[yaf_ForumAccess] ([GroupID], [ForumID], [AccessMaskID]) VALUES (3, 9, 3)
ALTER TABLE [dbo].[yaf_ForumAccess] CHECK CONSTRAINT ALL
统计:
alt text http://www.cricut.com/images/SqlQuery3.png
Stats
统计 IO 开启:
Table 'yaf_vaccess_group'. Scan count 0, logical reads 3, physical reads 0, read-ahead reads 0, lob logical reads 0, lob physical reads 0, lob read-ahead reads 0.
Table 'yaf_UserGroup'. Scan count 1, logical reads 709, physical reads 0, read-ahead reads 0, lob logical reads 0, lob physical reads 0, lob read-ahead reads 0.
Table 'yaf_AccessMask'. Scan count 0, logical reads 2, physical reads 0, read-ahead reads 0, lob logical reads 0, lob physical reads 0, lob read-ahead reads 0.
Table 'yaf_Group'. Scan count 0, logical reads 2, physical reads 0, read-ahead reads 0, lob logical reads 0, lob physical reads 0, lob read-ahead reads 0.
Table 'Worktable'. Scan count 2, logical reads 7, physical reads 0, read-ahead reads 0, lob logical reads 0, lob physical reads 0, lob read-ahead reads 0.
Table 'yaf_ForumAccess'. Scan count 0, logical reads 4, physical reads 0, read-ahead reads 0, lob logical reads 0, lob physical reads 0, lob read-ahead reads 0.
(1 row(s) affected)
(1 row(s) affected)
Table 'yaf_vaccess_group'. Scan count 0, logical reads 8, physical reads 0, read-ahead reads 0, lob logical reads 0, lob physical reads 0, lob read-ahead reads 0.
Table 'yaf_UserGroup'. Scan count 1, logical reads 709, physical reads 0, read-ahead reads 0, lob logical reads 0, lob physical reads 0, lob read-ahead reads 0.
Table 'yaf_AccessMask'. Scan count 0, logical reads 2, physical reads 0, read-ahead reads 0, lob logical reads 0, lob physical reads 0, lob read-ahead reads 0.
Table 'yaf_Group'. Scan count 0, logical reads 2, physical reads 0, read-ahead reads 0, lob logical reads 0, lob physical reads 0, lob read-ahead reads 0.
Table 'Worktable'. Scan count 2, logical reads 7, physical reads 0, read-ahead reads 0, lob logical reads 0, lob physical reads 0, lob read-ahead reads 0.
Table 'yaf_ForumAccess'. Scan count 0, logical reads 4, physical reads 0, read-ahead reads 0, lob logical reads 0, lob physical reads 0, lob read-ahead reads 0.
(1 row(s) affected)
(1 row(s) affected)
Table 'yaf_vaccess_group'. Scan count 0, logical reads 1340999, physical reads 0, read-ahead reads 3326, lob logical reads 0, lob physical reads 0, lob read-ahead reads 0.
Table 'yaf_UserGroup'. Scan count 1, logical reads 709, physical reads 0, read-ahead reads 0, lob logical reads 0, lob physical reads 0, lob read-ahead reads 0.
Table 'yaf_Group'. Scan count 0, logical reads 2, physical reads 0, read-ahead reads 0, lob logical reads 0, lob physical reads 0, lob read-ahead reads 0.
Table 'yaf_AccessMask'. Scan count 0, logical reads 2, physical reads 0, read-ahead reads 0, lob logical reads 0, lob physical reads 0, lob read-ahead reads 0.
Table 'Worktable'. Scan count 2, logical reads 7, physical reads 0, read-ahead reads 0, lob logical reads 0, lob physical reads 0, lob read-ahead reads 0.
Table 'yaf_ForumAccess'. Scan count 0, logical reads 4, physical reads 0, read-ahead reads 0, lob logical reads 0, lob physical reads 0, lob read-ahead reads 0.
(1 row(s) affected)
(1 row(s) affected)
yaf_vaccess_group View :
CREATE VIEW [dbo].[yaf_vaccess_group]
WITH SCHEMABINDING
AS
select
b.UserID,
c.ForumID,
d.AccessMaskID,
b.GroupID,
ReadAccess = convert(int,d.Flags & 1),
PostAccess = convert(int,d.Flags & 2),
ReplyAccess = convert(int,d.Flags & 4),
PriorityAccess = convert(int,d.Flags & 8),
PollAccess = convert(int,d.Flags & 16),
VoteAccess = convert(int,d.Flags & 32),
ModeratorAccess = convert(int,d.Flags & 64),
EditAccess = convert(int,d.Flags & 128),
DeleteAccess = convert(int,d.Flags & 256),
UploadAccess = convert(int,d.Flags & 512),
DownloadAccess = convert(int,d.Flags & 1024),
AdminGroup = convert(int,e.Flags & 1)
from
[dbo].[yaf_UserGroup] b
INNER JOIN [dbo].[yaf_ForumAccess] c on c.GroupID=b.GroupID
INNER JOIN [dbo].[yaf_AccessMask] d on d.AccessMaskID=c.AccessMaskID
INNER JOIN [dbo].[yaf_Group] e on e.GroupID=b.GroupID
CREATE UNIQUE CLUSTERED INDEX [yaf_vaccess_group_UserForum_PK] ON [dbo].[yaf_vaccess_group]
(
[UserID] ASC,
[ForumID] ASC,
[AccessMaskID] ASC,
[GroupID] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, SORT_IN_TEMPDB = OFF, IGNORE_DUP_KEY = OFF, DROP_EXISTING = OFF, ONLINE = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
GO
带 4 个插入件的 STATS IO 开启:
Table 'yaf_vaccess_group'. Scan count 0, logical reads 2, physical reads 0, read-ahead reads 0, lob logical reads 0, lob physical reads 0, lob read-ahead reads 0.
Table 'yaf_UserGroup'. Scan count 1, logical reads 709, physical reads 0, read-ahead reads 7, lob logical reads 0, lob physical reads 0, lob read-ahead reads 0.
Table 'yaf_AccessMask'. Scan count 0, logical reads 2, physical reads 0, read-ahead reads 0, lob logical reads 0, lob physical reads 0, lob read-ahead reads 0.
Table 'yaf_Group'. Scan count 0, logical reads 2, physical reads 0, read-ahead reads 0, lob logical reads 0, lob physical reads 0, lob read-ahead reads 0.
Table 'Worktable'. Scan count 2, logical reads 7, physical reads 0, read-ahead reads 0, lob logical reads 0, lob physical reads 0, lob read-ahead reads 0.
Table 'yaf_ForumAccess'. Scan count 0, logical reads 6, physical reads 0, read-ahead reads 0, lob logical reads 0, lob physical reads 0, lob read-ahead reads 0.
(1 row(s) affected)
(1 row(s) affected)
Table 'yaf_vaccess_group'. Scan count 0, logical reads 2, physical reads 0, read-ahead reads 0, lob logical reads 0, lob physical reads 0, lob read-ahead reads 0.
Table 'yaf_UserGroup'. Scan count 1, logical reads 709, physical reads 0, read-ahead reads 0, lob logical reads 0, lob physical reads 0, lob read-ahead reads 0.
Table 'yaf_AccessMask'. Scan count 0, logical reads 2, physical reads 0, read-ahead reads 0, lob logical reads 0, lob physical reads 0, lob read-ahead reads 0.
Table 'yaf_Group'. Scan count 0, logical reads 2, physical reads 0, read-ahead reads 0, lob logical reads 0, lob physical reads 0, lob read-ahead reads 0.
Table 'Worktable'. Scan count 2, logical reads 7, physical reads 0, read-ahead reads 0, lob logical reads 0, lob physical reads 0, lob read-ahead reads 0.
Table 'yaf_ForumAccess'. Scan count 0, logical reads 4, physical reads 0, read-ahead reads 0, lob logical reads 0, lob physical reads 0, lob read-ahead reads 0.
(1 row(s) affected)
(1 row(s) affected)
Table 'yaf_vaccess_group'. Scan count 0, logical reads 1220894, physical reads 0, read-ahead reads 0, lob logical reads 0, lob physical reads 0, lob read-ahead reads 0.
Table 'yaf_UserGroup'. Scan count 1, logical reads 709, physical reads 0, read-ahead reads 0, lob logical reads 0, lob physical reads 0, lob read-ahead reads 0.
Table 'yaf_Group'. Scan count 0, logical reads 2, physical reads 0, read-ahead reads 0, lob logical reads 0, lob physical reads 0, lob read-ahead reads 0.
Table 'yaf_AccessMask'. Scan count 0, logical reads 2, physical reads 0, read-ahead reads 0, lob logical reads 0, lob physical reads 0, lob read-ahead reads 0.
Table 'Worktable'. Scan count 2, logical reads 7, physical reads 0, read-ahead reads 0, lob logical reads 0, lob physical reads 0, lob read-ahead reads 0.
Table 'yaf_ForumAccess'. Scan count 0, logical reads 4, physical reads 0, read-ahead reads 0, lob logical reads 0, lob physical reads 0, lob read-ahead reads 0.
(1 row(s) affected)
(1 row(s) affected)
Table 'yaf_vaccess_group'. 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 0, lob logical reads 0, lob physical reads 0, lob read-ahead reads 0.
Table 'yaf_UserGroup'. Scan count 1, logical reads 709, physical reads 0, read-ahead reads 0, lob logical reads 0, lob physical reads 0, lob read-ahead reads 0.
Table 'yaf_AccessMask'. Scan count 0, logical reads 2, physical reads 0, read-ahead reads 0, lob logical reads 0, lob physical reads 0, lob read-ahead reads 0.
Table 'Worktable'. Scan count 2, logical reads 7, physical reads 0, read-ahead reads 0, lob logical reads 0, lob physical reads 0, lob read-ahead reads 0.
Table 'yaf_ForumAccess'. Scan count 0, logical reads 4, physical reads 0, read-ahead reads 0, lob logical reads 0, lob physical reads 0, lob read-ahead reads 0.
(1 row(s) affected)
(1 row(s) affected)
最佳答案
从您所展示的情况来看,不是第三个查询花费时间,而是实际打开检查约束的部分。
当重新打开约束时,它必须验证所有记录是否正确。这意味着扫描整个表。根据大小的不同,它可能受 IO 限制并击败硬盘驱动器。
所以,我认为你需要做出决定。要么完全放弃约束,要么停止打开和关闭它们。
关于performance - Ms Sql 2008 上的每第三次插入都很慢,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/2859780/