DBCC CHECKDB Error - Help Required

I have a customer who has reported some database corruption. The output of
DBCC CHECKDB ('CheckDB') is as follows:
Server: Msg 8935, Level 16, State 1, Line 1
Table error: Object ID 1685581043, index ID 1. The previous link (1:76577)
on page (1:76578) does not match the previous page (1:253212) that the paren
t
(1:64277), slot 165 expects for this page.
Server: Msg 8936, Level 16, State 1, Line 1
Table error: Object ID 1685581043, index ID 1. B-tree chain linkage
mismatch. (1:253212)->next = (1:76578), but (1:76578)->Prev = (1:76577).
Server: Msg 8934, Level 16, State 1, Line 1
Table error: Object ID 1685581043, index ID 1. The high key value on page
(1:253212) (level 0) is not less than the low key value in the parent (0:1),
slot 0 of the next page (1:76578).
Server: Msg 8978, Level 16, State 1, Line 1
Table error: Object ID 1685581043, index ID 1. Page (1:253212) is missing a
reference from previous page (1:76577). Possible chain linkage problem.
CHECKDB found 0 allocation errors and 4 consistency errors in table
'Student' (object ID 1685581043).
CHECKDB found 0 allocation errors and 4 consistency errors in database
'CheckDB'.
repair_rebuild is the minimum repair level for the errors found by DBCC
CHECKDB (LincsDB ).
(1 row(s) affected)
Attempting a DBCC CHECKDB ('CheckDB', REPAIR_REBUILD) yields the following
results:
Server: Msg 1505, Level 16, State 1, Line 1
CREATE UNIQUE INDEX terminated because a duplicate key was found for index
ID 2. Most significant primary key is '312037'.
Server: Msg 8935, Level 16, State 1, Line 1
Table error: Object ID 1685581043, index ID 1. The previous link (1:76577)
on page (1:76578) does not match the previous page (1:253212) that the paren
t
(1:64277), slot 165 expects for this page.
Server: Msg 8936, Level 16, State 1, Line 1
Table error: Object ID 1685581043, index ID 1. B-tree chain linkage
mismatch. (1:253212)->next = (1:76578), but (1:76578)->Prev = (1:76577).
Server: Msg 8934, Level 16, State 1, Line 1
Table error: Object ID 1685581043, index ID 1. The high key value on page
(1:253212) (level 0) is not less than the low key value in the parent (0:1),
slot 0 of the next page (1:76578).
Server: Msg 8978, Level 16, State 1, Line 1
Table error: Object ID 1685581043, index ID 1. Page (1:253212) is missing a
reference from previous page (1:76577). Possible chain linkage problem.
Could not repair this error.
Repairing this error requires other errors to be corrected first.
Repairing this error requires other errors to be corrected first.
Repairing this error requires other errors to be corrected first.
CHECKDB found 0 allocation errors and 4 consistency errors in table
'Student' (object ID 1685581043).
CHECKDB found 0 allocation errors and 4 consistency errors in database
'LincsDB'.
repair_rebuild is the minimum repair level for the errors found by DBCC
CHECKDB (LincsDB repair_rebuild).
The statement has been terminated.
(1 row(s) affected)
I can resolve the issue by dropping and recreating index id: 2 but this
involves dropping and re-creating a lot or related constraints (this is a
primary key).
Can anyone give me any pointers as to why this corruption may have occurred.
I have not seen this on any other customer databases so I don't think it is
an application error? Also, any suggestions on a better (simpler) way to
correct this problem?
Unfortunatley, the customers last viable backup is a couple of weeks out of
date and they are reluctant to restore and re-enter all the new data again.
Any help greatly appreciated,
Dave.I think that you could solve the problem by rebuilding the clustered index
with:
DBCC DBREINDEX (1685581043, 1)
This rebuilds the nonclustered index and at the same time fix the issues in
the nonclustered index 2. I am not 100% sure it will work in this situation.
These indexing problems can have a variety of causes. Most common are server
crashes, when a data page is only incompletely written to disk, and harddisk
errors. Make sure you have torn page detection on on your database, so you
get notified after a server restart if there is a similar problem, and check
the harddisk for any issues.
Jacco Schalkwijk
SQL Server MVP
"David Herd" <DavidHerd@.discussions.microsoft.com> wrote in message
news:281831FE-8ABD-447E-81A4-F8762C474E43@.microsoft.com...
>I have a customer who has reported some database corruption. The output of
> DBCC CHECKDB ('CheckDB') is as follows:
> Server: Msg 8935, Level 16, State 1, Line 1
> Table error: Object ID 1685581043, index ID 1. The previous link (1:76577)
> on page (1:76578) does not match the previous page (1:253212) that the
> parent
> (1:64277), slot 165 expects for this page.
> Server: Msg 8936, Level 16, State 1, Line 1
> Table error: Object ID 1685581043, index ID 1. B-tree chain linkage
> mismatch. (1:253212)->next = (1:76578), but (1:76578)->Prev = (1:76577).
> Server: Msg 8934, Level 16, State 1, Line 1
> Table error: Object ID 1685581043, index ID 1. The high key value on page
> (1:253212) (level 0) is not less than the low key value in the parent
> (0:1),
> slot 0 of the next page (1:76578).
> Server: Msg 8978, Level 16, State 1, Line 1
> Table error: Object ID 1685581043, index ID 1. Page (1:253212) is missing
> a
> reference from previous page (1:76577). Possible chain linkage problem.
> CHECKDB found 0 allocation errors and 4 consistency errors in table
> 'Student' (object ID 1685581043).
> CHECKDB found 0 allocation errors and 4 consistency errors in database
> 'CheckDB'.
> repair_rebuild is the minimum repair level for the errors found by DBCC
> CHECKDB (LincsDB ).
> (1 row(s) affected)
> Attempting a DBCC CHECKDB ('CheckDB', REPAIR_REBUILD) yields the following
> results:
> Server: Msg 1505, Level 16, State 1, Line 1
> CREATE UNIQUE INDEX terminated because a duplicate key was found for index
> ID 2. Most significant primary key is '312037'.
> Server: Msg 8935, Level 16, State 1, Line 1
> Table error: Object ID 1685581043, index ID 1. The previous link (1:76577)
> on page (1:76578) does not match the previous page (1:253212) that the
> parent
> (1:64277), slot 165 expects for this page.
> Server: Msg 8936, Level 16, State 1, Line 1
> Table error: Object ID 1685581043, index ID 1. B-tree chain linkage
> mismatch. (1:253212)->next = (1:76578), but (1:76578)->Prev = (1:76577).
> Server: Msg 8934, Level 16, State 1, Line 1
> Table error: Object ID 1685581043, index ID 1. The high key value on page
> (1:253212) (level 0) is not less than the low key value in the parent
> (0:1),
> slot 0 of the next page (1:76578).
> Server: Msg 8978, Level 16, State 1, Line 1
> Table error: Object ID 1685581043, index ID 1. Page (1:253212) is missing
> a
> reference from previous page (1:76577). Possible chain linkage problem.
> Could not repair this error.
> Repairing this error requires other errors to be corrected first.
> Repairing this error requires other errors to be corrected first.
> Repairing this error requires other errors to be corrected first.
> CHECKDB found 0 allocation errors and 4 consistency errors in table
> 'Student' (object ID 1685581043).
> CHECKDB found 0 allocation errors and 4 consistency errors in database
> 'LincsDB'.
> repair_rebuild is the minimum repair level for the errors found by DBCC
> CHECKDB (LincsDB repair_rebuild).
> The statement has been terminated.
> (1 row(s) affected)
> I can resolve the issue by dropping and recreating index id: 2 but this
> involves dropping and re-creating a lot or related constraints (this is a
> primary key).
> Can anyone give me any pointers as to why this corruption may have
> occurred.
> I have not seen this on any other customer databases so I don't think it
> is
> an application error? Also, any suggestions on a better (simpler) way to
> correct this problem?
> Unfortunatley, the customers last viable backup is a couple of weeks out
> of
> date and they are reluctant to restore and re-enter all the new data
> again.
> Any help greatly appreciated,
> Dave.|||Rebuilding the clustered index does not necessarily rebuild the
non-clustered indexes on the table. If the clustered index was created as a
unique index (e.g. Primary key), then the non-clustered indexes are not
rebuilt. They are rebuilt if the clustered index was non-unique.
"Jacco Schalkwijk" <jacco.please.reply@.to.newsgroups.mvps.org.invalid> wrote
in message news:%23OiY4EK2FHA.3188@.TK2MSFTNGP14.phx.gbl...
>I think that you could solve the problem by rebuilding the clustered index
>with:
> DBCC DBREINDEX (1685581043, 1)
> This rebuilds the nonclustered index and at the same time fix the issues
> in the nonclustered index 2. I am not 100% sure it will work in this
> situation.
> These indexing problems can have a variety of causes. Most common are
> server crashes, when a data page is only incompletely written to disk, and
> harddisk errors. Make sure you have torn page detection on on your
> database, so you get notified after a server restart if there is a similar
> problem, and check the harddisk for any issues.
> --
> Jacco Schalkwijk
> SQL Server MVP
>
> "David Herd" <DavidHerd@.discussions.microsoft.com> wrote in message
> news:281831FE-8ABD-447E-81A4-F8762C474E43@.microsoft.com...
>