Two main worries of an SQL DBA include making sure that data within the database is easily accessible to the right people and that there are no issues that pose any temporary or permanent threat to the data. While the first task revolves around assessing the performance of the database, the second task includes tackling database corruption and if possible, preventing it from occurring.
When it comes to achieving ideal SQL database performance, there are quite a few factors that should be assessed:
- CPU and memory utilization
- I/O bottlenecks
- Client Communications
- Configurations for operating system, storage and database installation
- And more
If all of these areas are properly addressed, a DBA can be sure that everything is working fine performance wise. However, the “handling corruption” bit of his task is not so straightforward. It involves understanding what factors can lead up to it and how to recover from it if it happens. The subsequent sections address both these points in detail.
Database Corruption and its Causes
The technical definition of SQL database corruption is any problem within the database that causes an improper storage of the actual zeros and ones needed to store the data at the disk or IO sub-system level. In layman terms, an SQL database is considered to be corrupted when the said database cannot be accessed and on trying a user is greeted with error messages such as “metadata corruption Error”, “SQL Server Table Corruption Error”, “Corruption on non-clustered indexes” or something similar.
For any organization that is used to fetching data through queries from their usually responsive SQL database, any such error message can send loud alarm bells ringing. With no clue as to why it happened or how to deal with it, a DBA can land into trouble and panic. If you’ve been there or are, we’d just like to say that before you completely lose your mind, read the information on database corruption that we’ve compiled here.
Common causes that can lead to SQL database corruption include:
- In almost 99% cases, it is the result of an error at the IO subsystem level – drives, controllers, and possibly even drivers.
- Incorrect “UPDATE” command execution or without proper parameters can lead to corruption.
- Upgrading SQL Server to a new version can also, at times, result in corruption
- Sudden system shutdown while working on the database can surely lead to improper or half-way read/write operations thus causing corruption
- Editing of database tables by multiple people simultaneously is another major reason
- Of course, virus/malware attacks can cause database corruption
- System issues such as low disk space or OS format can also play a part in causing SQL database corruption
How can I prevent database corruption?
If you’re looking for a way to prevent SQL database corruption from happening, well, you better stop looking. There’s no way to do that. That’s the honest, complete and bitter truth. All you need to do is accept that it can happen, at any time and due to any of the reasons mentioned above. At best, you can minimize the chance of it happening too soon or too often by regularly updating related drivers, controllers and drives. Plus, have a powerful anti-virus and firewall installed to protect against viruses. Try to avoid simultaneous edits to the database and keep it healthy by checking for errors after every few days (through in-built utilities discussed in the next section).
Over and above all this, the best way to safeguard against SQL database corruption is to take regular, detailed, backups of the entire database or at least a backup of database schema files and important tables. If you are armed with solid backups, you can rest assured that no level of database corruption can incur you losses.
If you take care of these points, you will have reduced the chances of a database corruption happening by at least 70%.
SQL Repair & Recovery
SQL database comes bundled with utilities to repair minor errors within it and help keep disasters at bay. These utilities are capable of scanning for bad sectors, mangled entries, and other storage problems that can creep up in storage environments. Some of such utilities include:
- DBCC CHECKDB with additional parameters such as
- DBCC CHECKTABLE
In addition to these utilities, to repair SQL database, you can use an application called Microsoft SQL Server Management Studio Express.
Though all of these utilities are efficient and come with the added advantage of being free of cost, they suffer from some limitations:
- These utilities might not be able to repair major corruption issues
- Some data loss might occur post database repair using them
- They need some form of technical expertise to be used
If you don’t have a backup of your database and want to repair it and recover data from it easily, without bothering about the limitations mentioned above, we suggest you use premium third-party SQL repair software like Stellar Phoenix SQL Database Repair
. This product serves as a reliable solution to repair corrupt MDF and NDF files that store all SQL data and recovers tables, triggers, indexes, keys, constraints, rules, and defaults accurately. With many additional features and wide compatibility with different SQL Server versions, this software is sure to be your one-stop solution for any SQL corruption problem.
Now that you’re better informed about SQL corruption, hope you don’t run to a service center immediately on seeing an error. Stay calm and use our valuable tips to cruise out of your troubles easily.