Is the SQL Server System Session ID 1-50?

I saw an article in the forum today asking why the session id of the SQL Server system ranges from 1 to 50. I have read this article before, these sessions are used by SQL Server to run system activities such as (lazy writer, ghost record cleanup, DTC commit/abort). Therefore, 50 Session IDs are reserved for SQL Server, user sessions start from 51.

Query user session usage before 2005:

 

Select * from sysprocesses wherespid <50

However, this restriction is no longer available after SQL Server 2005. I found the following article on MSDN: How It Works: System Sessions

Looking at a SQL Server error log it is formatted withDate,TimeAndSession identifier. Identifier of the identifiers contain the s following the spid value.

2008-01-08 20:03:36.12 spid5s

The s indicates that the session is a system session. prior to SQL Server 2005 all system sessions were limited to session ids less than 50. SQL Server 2005 lifted that restriction. in order identify a session during Ming system actives (lazy writer, ghost record cleanup, DTC commit/abort ,...) the sessions are identified as system sessions.

Instead of the older"Select * from sysprocesses where spid <50"You shoshould use"Select * from sys. dm_exec_sessions where is_user_process = 0"To identify system processes.

According to the preceding method, the Session ID of the system may exceed 50.

Select * from sys. dm_exec_sessionswhereis_user_process = 1

Is_user_process

Bit

If the session is a system session, it is 0. Otherwise, it is 1. Cannot be null

For more information, see http://msdn.microsoft.com/zh-cn/library/ms176013 (v = SQL .90). aspx