Monitor tempdb usage in SQL server easily using dynamic management views. At Bobcares, with our Server Management Service, we can handle your tempdb issues.

How To Monitor TempDB Usage In SQL Server?

Tempdb is a system database that is utilized by many SQL Server processes to temporarily store data. When a user, for example, creates a temporary table or declares a table variable, the data in these tables save to the SQL Server tempdb database. At the same time, the database engine can use the tempdb for a variety of internal tasks. Some of the common operations that use tempDB database are Hash Joins, CTE, and Triggers.

Tempdb handles multiple roles for critical functions that may influence the database engine’s performance. When the SQL database system is not properly configured, the tempdb database begins to develop rapidly, which can lead to a chaotic situation if the root reason is not identified.

In this article, we will see a simple method to monitor tempDB usage.

Monitor with “sys.dm_db_file_space_usage”

The sys.dm_db_file_space_usage is one of the dynamic management views which help to monitor the space usage information about the SQL Server database. The view returns information about the database file’s space use. The key feature of this view is that it returns point-in-time data that shows the current consumption.

We can use the following query to know four important space usage information about the tempdb database.

SELECT (SUM(unallocated_extent_page_count)*1.0/128) AS [Free space(MB)],(SUM(version_store_reserved_page_count)*1.0/128)  AS [Used Space by VersionStore(MB)],(SUM(internal_object_reserved_page_count)*1.0/128)  AS [Used Space by InternalObjects(MB)],(SUM(user_object_reserved_page_count)*1.0/128)  AS [Used Space by UserObjects(MB)]FROM tempdb.sys.dm_db_file_space_usage;

Let’s see each of the four space usage in detail.

Free Space

The unallocated space indicates the amount of free space in the tempdb database. This value is also visible in the tempdb database’s properties.

Used Space by VersionStore

Row-versioning isolation levels enable us to avoid conflicts between read and write operations. The operating approach in these isolation layers is based on storing the previously committed row version in tempdb. The version_store_reserved_page_count variable represents the total number of pages reserved for the version store.

Used Space by Internal Objects

SQL Server uses the SQL Server tempdb database to temporarily store some data during query execution to fulfill various internal functions. Table spool operators, for example, create a copy of the input data during statement execution and store it in SQL Server tempdb. The table spool operator in the following query allocates some space in the tempdb database.

SELECT  TOP 150 SO.AccountNumber FROM
Sales.SalesOrderHeader SO
INNER  JOIN Sales.SalesOrderDetailEnlarged SD
ON SO.ModifiedDate = SD.ModifiedDate

Used Space by UserObjects

Finally, the user_object_reserved_page_count field shows how many pages are on reserve when using table variables, temporary tables, and similar user objects.

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Conclusion

We have shown you a simple method from our Support team to monitor TempDB usage in SQL Server with the Dynamic Management views.