June 4, 2012 at 9:54 am
I have encountered the table corruption issue on one of the server. This server (SQL Server 2000 Ent edition on windows 2000) has publication database of pull-type merge replication. One of the table (MyDB.dbo.TestTABLE) got corrupted which is NOT being replicated (not a part of publication). Bad part is we do not have the good consistent backup.
Server: Msg 8928, Level 16, State 1, Line 1
Object ID 245575913, index ID 0: Page (1:26457) could not be processed. See other errors for details.
Server: Msg 8944, Level 16, State 1, Line 1
Table error: Object ID 245575913, index ID 0, page (1:26457), row 0. Test (nVarCols && (hdr->r_tagA & VARIABLE_COLUMNS)) failed. Values are 0 and 32.
Server: Msg 8976, Level 16, State 1, Line 1
Table error: Object ID 245575913, index ID 1. Page (1:26457) was not seen in the scan although its parent (1:2647915) and previous (1:1778496) refer to it. Check any previous errors.
Server: Msg 8978, Level 16, State 1, Line 1
Table error: Object ID 245575913, index ID 1. Page (1:713577) is missing a reference from previous page (1:26457). Possible chain linkage problem.
Server: Msg 8964, Level 16, State 1, Line 1
Table error: Object ID 245575913. The text, ntext, or image node at page (1:602493), slot 29, text ID 1083010711552 is not referenced.
DBCC results for 'TestTABLE'.
There are 3527305 rows in 68075 pages for object 'TestTABLE'.
CHECKTABLE found 0 allocation errors and 5 consistency errors in table 'TestTABLE' (object ID 245575913).
repair_allow_data_loss is the minimum repair level for the errors found by DBCC CHECKTABLE (MyDB.dbo.TestTABLE).
I have restored the database in test environment and came to know that dbcc checktable with repair_allow_data_loss is the only option to correct this problem. After repair SQL Server dropped the page (1:26457) index ID 0 ...
Next step is to correct the problem in production environment. Before I touch the production environment, I would like to know the risks and mitigation of this activity.
My concerns are:
1. Changing the database to single_user mode which is publisher in pull-type merge replication
2. Steps to be taken to disable\enable the merge replication before\after repair
Let me know if you have more inputs on this.
Thanks.
KRN
June 4, 2012 at 10:28 am
I think I have another option here without touching the publication database ...
1. Stop the application (to ensure that no more data added to table)
2. Take full backup of mydb database
3. Restore the database as mydb_corrupt
4. Change the mydb_corrupt to Single_user mode
5. Repair the table TestTABLE in mydb_corrupt with allow_data_loss
6. Rename the table TestTABLE to TestTABLE_old in mydb database
7. Export the TestTABLE from mydb_corrupt to mydb database
8. Run DBCC Checktable
9. Start the application and verify
10. Once all ok, drop the table TestTABLE_old
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