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Every third insert is slow at Ms Sql 2008

I have a function that writes 3 rows to an empty table as follows:

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)

For some reason, only the third request takes a long time, and each insertion grows longer.

Profiler Image http://www.cricut.com/images/SqlQuery.png Profiler Image

I tried to disable all restrictions in the table - the same result. I just can't understand why the first two will work so fast and the last will take so long.

Any help would be greatly appreciated.

Here are the statistics for the query launched by MSSMS:

Query:

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

Statistics:

alt text http://www.cricut.com/images/SqlQuery3.png
Statistics

STATS IO ON:

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

STATS IO ON w / 4 Inserts:

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)
+3
2

, vaccess_group. , , SQL Server , , /.

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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 = ON,  -- CHANGE HERE
    FILLFACTOR = 50, -- AND HERE
    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]

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+2

Source: https://habr.com/ru/post/1746039/

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