What Does SQL Server's sp_reset_connection Really Do?

Delving into the Depths of sp_reset_connection

sp_reset_connection, an integral component of SQL Server connection pooling, serves a crucial purpose in ensuring the proper functioning of reused connections. As connections are recycled from the pool, this internal stored procedure surreptitiously resets their settings to prepare them for subsequent use.

Despite its importance, the precise nature of sp_reset_connection's actions remains shrouded in mystery. To shed light on this enigma, let's unveil its multifaceted responsibilities.

Actions Performed by sp_reset_connection:

• Resets error states and numbers (@@error)
• Suspends child threads of parallel query execution contexts
• Waits for outstanding I/O operations
• Frees server-held buffers and unlocks buffer resources
• Releases connection-owned memory
• Clears work and temporary tables
• Cancels global cursors and closes SQL-XML handles
• Deletes SQL-XML work tables
• Closes all system and user tables
• Drops temporary objects
• Aborts open transactions
• Defects from distributed transactions
• Decrements reference count for database users, releasing shared database lock
• Frees acquired locks and releases handles
• Resets SET options to defaults
• Resets @@rowcount and @@identity values
• Reverts session level trace options set using dbcc traceon()

Actions NOT Performed by sp_reset_connection:

• Resets security context
• Reverts application role set using sp_setapprole
• Alters transaction isolation level

It is imperative to note that the exact behavior of sp_reset_connection may vary slightly across different versions of SQL Server. However, the purpose remains consistent: to return connections to a clean, reusable state. By understanding its functionality, database administrators and developers can optimize the use of connection pools, enhancing performance and maintaining stability.

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