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Server configuration: user connections

  • บทความ

Applies to: SQL Server

This article describes how to set the user connections server configuration option in SQL Server by using SQL Server Management Studio or Transact-SQL. The user connections option specifies the maximum number of simultaneous user connections that are allowed on an instance of SQL Server.

The actual number of user connections allowed also depends on the version of SQL Server you use, and also the limits of your application or applications and hardware. SQL Server allows a maximum of 32,767 user connections. Because user connections is a dynamic (self-configuring) option, SQL Server adjusts the maximum number of user connections automatically as needed, up to the maximum value allowable. For example, if only 10 users are logged in, each with 1 connection, 10 user connection objects are allocated. The same would happen if a single user establishes 10 connections. In most cases, you don't have to change the value for this option. The default is 0, which means that the maximum (32,767) user connections are allowed.

To determine the maximum number of user connections that your system allows, you can execute sp_configure or query the sys.configuration catalog view.

Recommendations

This option is an advanced option, and should be changed only by an experienced database administrator or certified SQL Server professional.

Using the user connections option helps avoid overloading the server with too many concurrent connections. You can estimate the number of connections based on system and user requirements. For example, on a system with many users, each user wouldn't usually require a unique connection. Connections can be shared among users. Users running OLE DB applications need a connection for each open connection object, users running Open Database Connectivity (ODBC) applications need a connection for each active connection handle in the application, and users running DB-Library applications need one connection for each process started that calls the DB-Library dbopen function.

Important

If you must use this option, don't set the value too high, because each connection has overhead regardless of whether the connection is being used. If you exceed the maximum number of user connections, you receive an error message and aren't able to connect until another connection becomes available.

Permissions

Execute permissions on sp_configure with no parameters or with only the first parameter are granted to all users by default. To execute sp_configure with both parameters to change a configuration option or to run the RECONFIGURE statement, a user must be granted the ALTER SETTINGS server-level permission. The ALTER SETTINGS permission is implicitly held by the sysadmin and serveradmin fixed server roles.

Use SQL Server Management Studio

  1. In Object Explorer, right-click a server and select Properties.

  2. Select the Connections node.

  3. Under Connections, in the Max number of concurrent connections box, type or select a value from 0 through 32767 to set the maximum number of users that are allowed to connect simultaneously to the instance of SQL Server.

  4. Restart SQL Server.

Use Azure Data Studio

  1. In the Connections pane under servers, right-click a server and Select Properties.

  2. Select the Connections node.

  3. Under Connections, in the Max number of concurrent connections box, type or select a value from 0 through 32767 to set the maximum number of users that are allowed to connect simultaneously to the instance of SQL Server.

  4. Restart SQL Server.

Use Transact-SQL

  1. Connect to the Database Engine.

  2. From the Standard bar, select New Query.

  3. Copy and paste the following example into the query window and select Execute. This example shows how to use sp_configure to configure the value of the user connections option to 325.

    USE master;
GO

EXECUTE sp_configure 'show advanced options', 1;
GO

RECONFIGURE;
GO

EXECUTE sp_configure 'user connections', 325;
GO

RECONFIGURE;
GO

EXECUTE sp_configure 'show advanced options', 0;
GO

RECONFIGURE;
GO

  4. Restart SQL Server.

For more information, see Server configuration options.

Follow up: After you configure the user connections option

The SQL instance must be restarted before the setting can take effect.

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