Obtain Exclusive Access to a SQL Server Database

Problem

In your earlier tip (Die Sucker – Killing SQL Server Process Ids (spids)) you outlined an option to kill spids (system process ids) to perform database restores or database maintenance when exclusive use of the database is needed.  Do any other options exist?  What are the advantages and disadvantages to these approaches?  When should one approach be used over another?

Solution

The typical approach to gaining exclusive use of a database is to use the ALTER DATABASE command.  This command has a few different parameters that can be helpful without writing any custom code to gain exclusive or restricted access to a database.  Check out the options and examples below in addition to some high level option analysis.

ALTER DATABASE Options

• SET – Determines the type of user access to the database
  • SINGLE_USER – Single user connection to the database
  • RESTRICTED_USER – Any number of users with db_owner or dbcreator or logins with sysadmin rights can connect to the database
  • MULTI_USER – Any number of users with rights to the database can connect to the database
• WITH ROLLBACK – Determines how the exclusive access to the database will take place
  • ROLLBACK AFTER integer [SECONDS] – Rollback the spids after a particular number of seconds
  • ROLLBACK IMMEDIATE – Rollback the spids immediately
  • NO_WAIT – If all of the spids do not commit or rollback immediately the request to put the database in an exclusive state will fail

ALTER DATABASE Example

ALTER DATABASE – Advantages and Disadvantages

• Advantages
  • Easily incorporated into scripts for database restoration processes
  • A fair amount of flexibility based on the options listed above without having to write any custom code
• Disadvantages
  • Could potentially have a long rollback process
    • The typical resolution would be to use the NO_WAIT option
  • Could potentially kill spids that need to finish for business reasons that are unexpectedly running slow

Kill spid Script – Advantages and Disadvantages

• Advantages
  • Can modify the script to determine if a specific application is running and determine if any spids should be killed or just wait for a finite period of time with a WAITFOR command
  • Can modify the script to conditionally issue the ALTER DATABASE statement as opposed to the KILL commands to determine if the database should be put in an exclusive state
  • Can modify the script to meet conditional needs
• Disadvantages
  • Could potentially have a long rollback process
    • Since you are using custom code and have knowledge of your environment you could conditionally kill spids as opposed to just killing all spids
  • Could potentially kill your own spid
    • The typical resolution would be to connect to a database that will not have spids killed as a portion of the process

Next Steps

• As is the case in many scenarios, a variety of options exist to address an issue or resolve a problem.  What is really necessary is to review the scenario, gather as much information as possible, determine the viable options then determine the best approach based on previous steps.  When it comes to killing spids for whatever reason, this scenario is no different.
• For additional information, reference the following:
  • Die Sucker – Killing SQL Server Process Ids (spids)
  • ALTER DATABASE (Transact-SQL) – SQL Server 2005
  • ALTER DATABASE – SQL Server 2000
• Special thanks to Mike, Ted and Robert of the MSSQLTips.com for feedback from the Die Sucker – Killing SQL Server Process Ids (spids) tip to serve as input for this tip.  Thanks again!

Jeremy Kadlec

Jeremy Kadlec is a Founder, Editor and Author at MSSQLTips.com with more than 300 contributions and 25+ years of SQL Server experience. Jeremy leads a team of more than 300 authors helping millions of SQL Server professionals around the globe every second of the day for the last 20 years.  He is also the CTO @ Edgewood Solutions and a six-time SQL Server MVP based on his community contributions. Jeremy brings 25+ years of SQL Server DBA and Developer knowledge to the community and holds a bachelor’s degree from SSU and master’s degree from UMBC.