Tempdb is a system database. It is a temporary workspace for storing temporary tables that hold intermediate results during sorting or query processing. Tempdb is re-created newly from stored configuration each time the SQL Server service starts.

How to open the Tempdb drilldown

From the Spotlight Client

  1. Select the connection from the left Connections pane.
  2. Click Monitor | Tempdb from the ribbon.
    Tempdb drilldown for SQL Server

About the Tempdb drilldown

Use this drilldown to determine at a glance how much space is being consumed by tempdb. Spotlight also warns in advance problems surrounding disk space usage on Tempdb. These problems include: a fixed size Tempdb about to be filled up, a non-fixed size Tempdb trying to auto grow on a volume that does not have enough space for an auto grow.

Configuration Health page

Investigate Tempdb configuration.

Spotlight verifies the following best practices:

  • Tempdb is split into a number of files appropriate to the number of processors in the system configuration.
  • Tempdb files are isolated on a drive if I/O rates are significant.
  • Tempdb auto growth is turned off.

Usage page

Investigate Tempdb space usage.

Identify the transactions consuming the most space.

Tempdb Space Used chart

The tempdb space used chart represents “points in time” usage. It is populated from sys.dm_db_file_space_usage.

The chart plots the following:

  • User objects: System tables and indexes, user defined tables and indexes, global temporary tables, local temporary tables and indexes, table variables and tables returned in table-valued functions.
  • Internal objects: Work tables (for cursors, spool operations, temporary large objects LOBs), work files (for hash join and hash aggregate operations), intermediate sort results (for rebuilding indexes, group by, order by and union)
  • Version store: There are two version stores in Tempdb. The online index build version store is used for online index builds in all databases. The common version store is used for all other data modification operations in all databases.
  • Free space: Unused space.

Version Store Size Change chart / Version Store Size chart

Use these charts to determine if the Tempdb version store is growing. Is the rate of growth greater than the rate of cleanup?

There are two version stores in Tempdb. The online index build version store is used for online index builds in all databases. The common version store is used for all other data modification operations in all databases.

These charts are populated using SQLTempDBPerfCounters.

Top 25 Tempdb sessions grid

The Top 25 sessions grid captures Tempdb space usage at the time the last SQL statement for the session completed. It is populated from sys.dm_db_file_space_usage.

Contention page

Investigate: Is the Azure SQL Managed instance experiencing Tempdb contention? If so, which user or application is the cause?

When the Tempdb database is heavily used the Azure SQL Managed instance may experience contention when it tries to allocate pages. Depending on the degree of contention, this may cause queries and requests that involve Tempdb to be unresponsive for short periods of time.

Note that Tempdb contention refers to a bottleneck for threads trying to access allocation pages that are in-memory; it has nothing to do with I/O.

Wait Time chart

Is the Azure SQL Managed instance experiencing Tempdb contention? The Tempdb Wait Time chart plots wait contention over time for the resource types PFS (page free space), GAM (global allocation map), SGAM (shared global allocation map).

Sessions involved in this contention grid

Which user or application is the cause of Tempdb contention?