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Creating a Driver Application - Multithreaded Applications

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Applies to: SQL Server Azure SQL Database Azure SQL Managed Instance Azure Synapse Analytics Analytics Platform System (PDW)

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). The SQL Server Native Client (SQLNCLI or SQLNCLI11) and the legacy Microsoft OLE DB Provider for SQL Server (SQLOLEDB) are not recommended for new application development. Switch to the new Microsoft OLE DB Driver (MSOLEDBSQL) for SQL Server or the latest Microsoft ODBC Driver for SQL Server going forward. For SQLNCLI that ships as a component of SQL Server Database Engine (versions 2012 through 2019), see this Support Lifecycle exception.

The SQL Server Native Client ODBC driver is a multithreaded driver. Writing a multithreaded application is an alternative to using asynchronous calls to process multiple ODBC calls. A thread can make a synchronous ODBC call, and other threads can process while the first thread is blocked waiting for the response to its call. This model is more efficient than making asynchronous calls because it eliminates overhead such as network traffic and making repeated ODBC function calls testing for SQL_STILL_EXECUTING.

Asynchronous mode is still an effective method of processing. The performance improvements of a multithreaded model are not enough to justify rewriting asynchronous applications. If users are converting DB-Library applications that use the DB-Library asynchronous model, it is easier to convert them to the ODBC asynchronous model.

See Also

Creating a SQL Server Native Client ODBC Driver Application