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sp_who (Transact-SQL)

Provides information about current users, sessions, and processes in an instance of the Microsoft SQL Server Database Engine. The information can be filtered to return only those processes that are not idle, that belong to a specific user, or that belong to a specific session.

Topic link iconTransact-SQL Syntax Conventions

sp_who [ [ @loginame = ] 'login' | session ID | 'ACTIVE' ]
[ @loginame = ] 'login' | session ID | 'ACTIVE'

Is used to filter the result set.

login is sysname that identifies processes belonging to a particular login.

session ID (SPID in SQL Server 2000 and earlier) is a session identification number belonging to the SQL Server instance. session ID is smallint.

ACTIVE excludes sessions that are waiting for the next command from the user.

If no value is provided, the procedure reports all sessions belonging to the instance.

0 (success) or 1 (failure)

sp_who returns a result set with the following information.

Column

Data type

Description

spid

smallint

Session ID.

ecid

smallint

Execution context ID of a given thread associated with a specific session ID.

ECID = {0, 1, 2, 3, ...n}, where 0 always represents the main or parent thread, and {1, 2, 3, ...n} represent the subthreads.

status

nchar(30)

Process status. The possible values are:

dormant. SQL Server is resetting the session.

running. The session is running one or more batches. When Multiple Active Result Sets (MARS) is enabled, a session can run multiple batches. For more information, see Using Multiple Active Result Sets (MARS).

background. The session is running a background task, such as deadlock detection.

rollback. The session has a transaction rollback in process.

pending. The session is waiting for a worker thread to become available.

runnable. The session's task is in the runnable queue of a scheduler while waiting to get a time quantum.

spinloop. The session's task is waiting for a spinlock to become free.

suspended. The session is waiting for an event, such as I/O, to complete.

loginame

nchar(128)

Login name associated with the particular process.

hostname

nchar(128)

Host or computer name for each process.

blk

char(5)

Session ID for the blocking process, if one exists. Otherwise, this column is zero.

When a transaction associated with a specified session ID is blocked by an orphaned distributed transaction, this column will return a '-2' for the blocking orphaned transaction.

dbname

nchar(128)

Database used by the process.

cmd

nchar(16)

Database Engine command (Transact-SQL statement, internal Database Engine process, and so on) executing for the process.

request_id

int

ID for requests running in a specific session.

In case of parallel processing, subthreads are created for the specific session ID. The main thread is indicated as spid = <xxx> and ecid =0. The other subthreads have the same spid = <xxx>, but with ecid > 0.

A blocking process, which may have an exclusive lock, is one that is holding resources that another process needs.

In SQL Server 2000 and later, all orphaned distributed transactions are assigned the session ID value of '-2'. Orphaned distributed transactions are distributed transactions that are not associated with any session ID. For more information, see Using Marked Transactions (Full Recovery Model).

SQL Server 2000 and later reserves session ID values from 1 through 50 for internal use, and session ID values 51 or higher represent user sessions.

Requires VIEW SERVER STATE permission on the server to see all executing sessions on the instance of SQL Server. Otherwise, the user sees only the current session.

A. Listing all current processes

The following example uses sp_who without parameters to report all current users.

USE master;
GO
EXEC sp_who;
GO

B. Listing a specific user's process

The following example shows how to view information about a single current user by login name.

USE master;
GO
EXEC sp_who 'janetl';
GO

C. Displaying all active processes

USE master;
GO
EXEC sp_who 'active';
GO

D. Displaying a specific process identified by a session ID

USE master;
GO
EXEC sp_who '10' --specifies the process_id;
GO
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