Connecting to an Azure SQL database

Connecting to an Azure SQL database

SQL Server 2012

This topic discusses issues when using the Microsoft JDBC Driver for SQL Server to connect to a SQL Azure Database. For more information about connecting to a SQL Azure Database, see:

When connecting to a SQL Azure Database, you should connect to the master database to call SQLServerDatabaseMetaData.getCatalogs.

SQL Azure Database does not support returning the entire set of catalogs from a user database. SQLServerDatabaseMetaData.getCatalogs uses the sys.databases view to get the catalogs. Please refer to the discussion of permissions in sys.databases (SQL Azure Database) to understand SQLServerDatabaseMetaData.getCatalogs behavior on a SQL Azure Database.

Connections Dropped

When connecting to a SQL Azure Database, idle connections may be terminated by a network component (such as a firewall) after a period of inactivity. There are two types of idle connections, in this context:

  • Idle at the TCP layer, where connections can be dropped by any number of network devices.

  • Idle by the SQL Azure Gateway, where TCP keepalive messsages might be occurring (making the connection not idle from a TCP perspective), but not had an active query in 30 minutes. In this scenario, the Gateway will determine that the TDS connection is idle at 30 minutes and terminate the connection.

To avoid dropping idle connections by a network component, the following registry settings (or their non-Windows equivalents) should be set on the operating system where the driver is loaded:

Registry Setting

Recommended Value







You must then restart the computer for the registry settings to take effect.

To accomplish this when running in Windows Azure create a startup task to add the registry keys. For example, add the following Startup task to the service definition file:

    <Task commandLine="AddKeepAlive.cmd" executionContext="elevated" taskType="simple">

Then add a AddKeepAlive.cmd file to your project. Set the "Copy to Output Directory" setting to Copy always. The following is a sample AddKeepAlive.cmd file:

if exist keepalive.txt goto done
time /t > keepalive.txt
REM Workaround for JDBC keep alive on SQL Azure
REG ADD HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters /v KeepAliveTime /t REG_DWORD /d 30000 >> keepalive.txt
REG ADD HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters /v KeepAliveInterval /t REG_DWORD /d 1000 >> keepalive.txt
REG ADD HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters /v TcpMaxDataRetransmission /t REG_DWORD /d 10 >> keepalive.txt
shutdown /r /t 1
Appending the Server Name to the UserId in the Connection String

Prior to the 4.0 version of the Microsoft JDBC Driver for SQL Server, when connecting to a SQL Azure Database, you were required to append the server name to the UserId in the connection string. For example, user@servername. Beginning in version 4.0 of the Microsoft JDBC Driver for SQL Server, it is no longer necessary to append @servername to the UserId in the connection string.

Using Encryption Requires Setting hostNameInCertificate

When connecting to a SQL Azure Database, you should specify hostNameInCertificate if you specify encrypt=true. (If the server name in the connection string is shortName.domainName, set the hostNameInCertificate property to *.domainName.)

For example:

jdbc:sqlserver://;databaseName= myDatabase;user=myName;password=myPassword;encrypt=true;hostNameInCertificate= *;
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