Tuesday, April 6, 2010

False Positive and Database Consistency in Microsoft SQL Server

Are you facing various instances of the 'False Positive' on your Microsoft SQL Server when you run DBCC CHECKDB statement for checking database consistency? The problem may occur due to inconsistency of the MDF (Master Database File) of MS SQL Server. Database inconsistency can be due to numerous reasons, such as database corruption, missing database objects, and more. In all such cases, the database becomes completely unusable and you face severe data loss problems. In such circumstances, it becomes essential to perform SQL Database Recovery to overcome the problem.

For instance, when you run DBCC CHECKDB statement on your SQL Server database, it gives consistency errors in database tables. However, if you run DBCC CHECKTABLE statement to repair the table and fix inconsistency problems, it does not display any errors. When you face a false positive situation, you get either of the below errors:

“DBCC CHECKDB is performing an exhaustive search of indexes for possible inconsistencies.”


“SQL Server has encountered 1 occurrence(s) of I/O requests taking longer than 15 seconds to complete on file in database .”

At the same time, Application Event Log of MS SQL Server may contain entries similar to the following ones:

Msg 8978, Sev 16, State 1, Line 1 : Table error: Object ID 1789795471, index ID 1, partition ID 72057602467495936, alloc unit ID 72057602585395200 (type In-row data). Page (1:2387522) is missing a reference from previous page (1:2387521). Possible chain linkage problem. [SQLSTATE 42000]
Msg 8958, Sev 16, State 1, Line 1 : repair_allow_data_loss is the minimum repair level for the errors found by DBCC CHECKDB . [SQLSTATE 01000]


The problem occurs due to inconsistency or corruption in the MDF file. It may be due to unexpected system shutdown, virus infection, and other such reasons.


You can get your database in working state by restoring it from an updated backup. After restoring the database, you must run database defragmentation. However, if the backup is not current, then only SQL Server Recovery can help you to extract inaccessible data.

Effective and absolute recovery is possible with SQL Recovery software. These are powerful third-party tools, which scan whole database and retrieve all damaged and inaccessible data from it. You need not have sound technical skills to use these MS SQL Recovery software as they have simple graphical user interface.

SQL Recovery is the most advanced utility that ensures perfect recovery of damaged SQL Server database. The software repairs and restores MDF files of Microsoft SQL Server 2008, 2005, and 2000. It recovers all SQL Server database objects such as tables, reports, forms, triggers, and stored procedures.

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