The tempdb system database is a global resource that is available to all users connected to the instance of SQL Server and is used to hold the following
Temporary user objects that are explicitly created, such as: global or local temporary tables, temporary stored procedures, table variables, or cursors.
Operations within tempdb are minimally logged. This enables transactions to be rolled back. tempdb is re-created every time SQL Server is started so that the system always starts with a clean copy of the database. Temporary tables and stored procedures are dropped automatically on disconnect, and no connections are active when the system is shut down. Therefore, there is never anything in tempdb to be saved from one session of SQL Server to another. Backup and restore operations are not allowed on tempdb.
In SQL Server, tempdb performance is improved in the following ways
Temporary tables and table variables may be cached. Caching allows operations that drop and create the temporary objects to execute very quickly and reduces page allocation contention.
Allocation page latching protocol is improved. This reduces the number of UP (update) latches that are used.
Logging overhead for tempdb is reduced. This reduces disk I/O bandwidth consumption on the tempdb log file.
Setup adds multiple tempdb data files during a new instance installation. This task can be accomplished with the new UI input control on the Database Engine Configuration section and a command line parameter /SQLTEMPDBFILECOUNT. By default, setup will add as many tempdb files as the CPU count or 8, whichever is lower.
When there are multiple tempdb data files, all files will autogrow at same time and by the same amount depending on growth settings. Trace flag 1117 is no longer required.
All allocations in tempdb use uniform extents. Trace flag 1118 is no longer required.
For the primary filegroup, the AUTOGROW_ALL_FILES property is turned on and the property cannot be modified.