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What Are SQL Server Consistency Checks

SQL Server constantly checks several things to ensure the proper functioning of the databases and the instance. Some of the checks that SQL Server performs include:

  • Data consistency checks: SQL Server regularly checks the consistency of the data in the databases to ensure that the data is valid and that there are no corruption issues. These checks include checks for consistency among the different pages of a database, checks for consistency of indexes, and checks for consistency of database structures.

  • Performance monitoring: SQL Server constantly monitors the performance of the instance and the databases, including monitoring of resource usage such as CPU, memory, and disk I/O, to identify and troubleshoot performance issues.

  • Security checks: SQL Server checks the security of the instance and the databases, including monitoring of login attempts, validating the authenticity of users, and monitoring for security breaches.

  • Backup and recovery checks: SQL Server checks the backups of the databases to ensure that they are complete and can be used for recovery in case of a disaster. This includes checking the backup files for consistency and completeness, and monitoring the backup schedule.

  • Job execution: SQL Server checks the status of scheduled jobs, such as backups, indexing, and other maintenance tasks, to ensure they are running as expected.

  • Indexing: SQL Server regularly checks and updates indexes on the databases to ensure that data can be retrieved quickly and efficiently.

  • Logging: SQL Server logs events, errors, and other information about the instance and databases, which can be used for troubleshooting and auditing.

  • Memory management: SQL Server constantly checks and manages the memory usage of the instance and the databases to ensure that resources are used efficiently and that there are no memory leaks.

  • Automatic Updates: SQL Server also checks for updates that can improve the security and performance of the instance, and it can also automatically install them.

These are some of the checks that SQL Server performs, but it's important to mention that SQL Server also performs many other checks and tasks to ensure the proper functioning of the instance and the databases.


The frequency at which SQL Server performs certain checks and tasks can vary depending on the specific check or task, as well as the specific needs of the organization. Here are some general guidelines on the frequency of some of the checks and tasks that SQL Server performs:

  • Data consistency checks: These checks are typically performed on a regular basis, such as daily or weekly, to ensure that the data is valid and that there are no corruption issues.

  • Performance monitoring: Performance monitoring is a constant process, SQL Server is constantly monitoring the performance of the instance and the databases, which allows it to quickly identify and troubleshoot performance issues.

  • Security checks: These checks are also performed on a regular basis, such as daily or weekly, to ensure that the instance and databases are secure and that there are no security breaches.

  • Backup and recovery checks: SQL Server checks the backups of the databases on a regular basis, such as daily or weekly, to ensure that they are complete and can be used for recovery in case of a disaster.

  • Job execution: SQL Server checks the status of scheduled jobs on a regular basis, such as daily or weekly, depending on the job's schedule.

  • Indexing: SQL Server regularly checks and updates indexes on the databases to ensure that data can be retrieved quickly and efficiently. The frequency of indexing is determined by the data modification rate on the databases, it can be done daily, weekly or monthly.

  • Logging: SQL Server logs events, errors, and other information about the instance and databases on a constant basis, which can be used for troubleshooting and auditing.

  • Memory management: SQL Server constantly checks and manages the memory usage of the instance and the databases, to ensure that

What Command Do I Run To See This Data?

DBCC CHECKDB is a command in SQL Server that is used to check the physical and logical consistency of a database. It performs a variety of checks on the data and the database structures, including checks on the data pages, index pages, and allocation structures, as well as checks on the database consistency.

When DBCC CHECKDB is executed, it performs the following checks on the database:

  • Consistency checks: DBCC CHECKDB checks the consistency of the data and database structures, such as the data pages, index pages, and allocation structures. It verifies that the structures of the database are consistent with the data stored in the pages.

  • Integrity checks: DBCC CHECKDB checks the integrity of the data and the database structures, such as the data pages, index pages, and allocation structures. It verifies that the data is consistent with the structures of the database.

  • Allocation checks: DBCC CHECKDB checks the allocation of the data and the database structures, such as the data pages, index pages, and allocation structures. It verifies that the data and the structures of the database are properly allocated.

  • Repair options: DBCC CHECKDB can also repair errors found during the consistency checks, such as allocation errors, consistency errors, and integrity errors.

DBCC CHECKDB can be run on a specific database by calling it with the name of the database, or it can be run on all databases by using the command DBCC CHECKDB (‘ALL_DATABASES’)


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