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Server configuration: network packet size

  • Artikkeli

Applies to: SQL Server

This article describes how to configure the network packet size server configuration option in SQL Server by using SQL Server Management Studio or Transact-SQL. The network packet size option sets the packet size (in bytes) that's used across the whole network. Packets are the fixed-size chunks of data that transfer requests and results between clients and servers. The default packet size is 4,096 bytes.

Note

Don't change the packet size unless you're certain that it will improve performance. For most applications, the default packet size is best.

The setting takes effect immediately without restarting the server.

Limitations

The maximum network packet size for encrypted connections is 16,383 bytes.

Note

If MARS is enabled, the SMUX provider will add a 16-byte header to the packet before TLS encryption, reducing the maximum network packet size to 16368 bytes.

Recommendations

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

If an application does bulk copy operations or sends or receives large amounts of text or image data, a packet size larger than the default might improve efficiency because it results in fewer network read-and-write operations. If an application sends and receives small amounts of information, the packet size can be set to 512 bytes, which is sufficient for most data transfers.

On systems that are using different network protocols, set network packet size to the size for the most common protocol used. The network packet size option improves network performance when network protocols support larger packets. Client applications can override this value.

You can also call OLE DB, Open Database Connectivity (ODBC), and DB-Library functions request a change the packet size. If the server can't support the requested packet size, the Database Engine sends a warning message to the client. In some circumstances, changing the packet size might lead to a communication link failure, such as the following error:

Native Error: 233, no process is on the other end of the pipe.

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 Advanced node.

  3. Under Network, select a value for the Network Packet Size box.

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 set the value of the network packet size option to 6500 bytes.

    USE master;
GO

EXECUTE sp_configure 'show advanced options', 1;
GO

RECONFIGURE;
GO

EXECUTE sp_configure 'network packet size', 6500;
GO

RECONFIGURE;
GO

EXECUTE sp_configure 'show advanced options', 0;
GO

RECONFIGURE;
GO

For more information, see Server configuration options.

Configure network packet size on the client side

The following table provides examples of some data connection technologies that you can use to connect to SQL Server and how to control the network packet size when using these in client applications. For a complete list of various data connection technologies that you can use to connect to SQL Server, see Homepage for client programming to Microsoft SQL Server:

Client library Option Default
SQLSetConnectAttr Function SQL_ATTR_PACKET_SIZE Use server side
Setting the connection properties setPacketSize(int packetSize) 8000
ADO.NET - Microsoft.Data.SqlClient PacketSize 8000
ADO.NET - System.Data.SqlClient PacketSize 8000
Initialization and Authorization Properties SSPROP_INIT_PACKETSIZE 0 (use server side)

You can monitor the Audit Login event or the ExistingConnection event in SQL Profiler to determine the network packet size of a client connection.

If the application's connection string contains a value for the network packet size, then that value is used for communication. If the connection string doesn't contain a value, the drivers use defaults for the network packet size. For example, as described in the preceding table, SqlClient applications use a default packet size of 8000, whereas ODBC applications use the packet size you've configured on the server.

Important

The SQL Server Native Client (often abbreviated SNAC) has been removed from SQL Server 2022 (16.x) and SQL Server Management Studio 19 (SSMS). Both the SQL Server Native Client OLE DB provider (SQLNCLI or SQLNCLI11) and the legacy Microsoft OLE DB Provider for SQL Server (SQLOLEDB) aren't recommended for new development. Switch to the new Microsoft OLE DB Driver for SQL Server or the latest Microsoft ODBC Driver for SQL Server going forward.

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