What does “exec sp_reset_connection” mean in Sql Server Profiler? [duplicate]

问题

Trying to understand what Sql Profiler means by emitting \"sp_reset_connection\".

I have the following, \"exec sp_reset_connection\" line followed by BatchStarting and Completed,

RPC:Completed       exec sp_reset_connection
SQL:BatchStarting   SELECT [c].[TestID] AS [TestID], [c].[Description] AS [Description] FROM [dbo].[Test] AS [c]
SQL:BatchCompleted  SELECT [c].[TestID] AS [TestID], [c].[Description] AS [Description] FROM [dbo].[Test] AS [c]

Basically does first line \"exec sp_reset_connection\" mean the whole process (my connection was opened, the select stmt is run, then the connection is closed and released back to pool) just take place? Or my connection is still in open stage.

And, why does the sp_reset_connection executed before my own select statement, shouldn\'t it the reset come after user\'s sql?

I\'m trying to know is there a way to know in more detail when a connection is opened and closed?

By seeing \"exec sp_reset_connection\", does that mean my connection is closed?

回答1:

Like the other answers said, sp_reset_connection indicates that connection pool is being reused. Be aware of one particular consequence!

Jimmy Mays' MSDN Blog said:

sp_reset_connection does NOT reset the transaction isolation level to the server default from the previous connection's setting.

UPDATE: Starting with SQL 2014, for client drivers with TDS version 7.3 or higher, the transaction isolation levels will be reset back to the default.

ref: SQL Server: Isolation level leaks across pooled connections

Here is some additional information:

What does sp_reset_connection do?

Data access API's layers like ODBC, OLE-DB and System.Data.SqlClient all call the (internal) stored procedure sp_reset_connection when re-using a connection from a connection pool. It does this to reset the state of the connection before it gets re-used, however nowhere is documented what things get reset. This article tries to document the parts of the connection that get reset.

sp_reset_connection resets the following aspects of a connection:

All error states and numbers (like @@error)

Stops all EC's (execution contexts) that are child threads of a parent EC executing a parallel query

Waits for any outstanding I/O operations that is outstanding

Frees any held buffers on the server by the connection

Unlocks any buffer resources that are used by the connection

Releases all allocated memory owned by the connection

Clears any work or temporary tables that are created by the connection

Kills all global cursors owned by the connection

Closes any open SQL-XML handles that are open

Deletes any open SQL-XML related work tables

Closes all system tables

Closes all user tables

Drops all temporary objects

Aborts open transactions

Defects from a distributed transaction when enlisted

Decrements the reference count for users in current database which releases shared database locks

Frees acquired locks

Releases any acquired handles

Resets all SET options to the default values

Resets the @@rowcount value

Resets the @@identity value

Resets any session level trace options using dbcc traceon()

Resets CONTEXT_INFO to NULL in SQL Server 2005 and newer _{[ not part of the original article ]}

sp_reset_connection will NOT reset:

Security context, which is why connection pooling matches connections based on the exact connection string

Application roles entered using sp_setapprole, since application roles can not be reverted

Note: I am including the list here as I do not want it to be lost in the ever transient web.

回答2:

It's an indication that connection pooling is being used (which is a good thing).

回答3:

Note however:

If you issue SET TRANSACTION ISOLATION LEVEL in a stored procedure or trigger, when the object returns control the isolation level is reset to the level in effect when the object was invoked. For example, if you set REPEATABLE READ in a batch, and the batch then calls a stored procedure that sets the isolation level to SERIALIZABLE, the isolation level setting reverts to REPEATABLE READ when the stored procedure returns control to the batch.

http://msdn.microsoft.com/en-us/library/ms173763.aspx

来源：https://stackoverflow.com/questions/641120/what-does-exec-sp-reset-connection-mean-in-sql-server-profiler

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sql-server

database-connection

sql-server-profiler

sp-reset-connection