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15/11/2013

Tạo 1 stored tương tự sp_who2 sử dụng DMVs (sp_who3)

The following code generates the same information found in sp_who2, along with some additional troubleshooting information. It also contains the SQL Statement being run, so instead of having to execute a separate DBCC INPUTBUFFER, the statement being executed is shown in the results.

Unlike sp_who2, this custom sp_who3 only shows sessions that have a current executing request.

What is also shown is the reads and writes for the current command, along with the number of reads and writes for the entire SPID. It also shows the protocol being used (TCP, NamedPipes, or Shared Memory).

The lead blocker below will show in the BlkBy column as -1.

CREATE PROCEDURE [dbo].[sp_who3]

AS
BEGIN

SET TRANSACTION ISOLATION LEVEL READ UNCOMMITTED

SELECT
    SPID                = er.session_id
    ,BlkBy              = CASE WHEN lead_blocker = 1 THEN -1 ELSE er.blocking_session_id END
    ,ElapsedMS          = er.total_elapsed_time
    ,CPU                = er.cpu_time
    ,IOReads            = er.logical_reads + er.reads
    ,IOWrites           = er.writes    
    ,Executions         = ec.execution_count
    ,CommandType        = er.command        
    ,LastWaitType       = er.last_wait_type  
    ,ObjectName         = OBJECT_SCHEMA_NAME(qt.objectid,dbid) + '.' + OBJECT_NAME(qt.objectid, qt.dbid)
    ,SQLStatement       =
        SUBSTRING
        (
            qt.text,
            er.statement_start_offset/2,
            (CASE WHEN er.statement_end_offset = -1
                THEN LEN(CONVERT(nvarchar(MAX), qt.text)) * 2
                ELSE er.statement_end_offset
                END - er.statement_start_offset)/2
        )      
    ,STATUS             = ses.STATUS
    ,[Login]            = ses.login_name
    ,Host               = ses.host_name
    ,DBName             = DB_Name(er.database_id)
    ,StartTime          = er.start_time
    ,Protocol           = con.net_transport
    ,transaction_isolation =
        CASE ses.transaction_isolation_level
            WHEN 0 THEN 'Unspecified'
            WHEN 1 THEN 'Read Uncommitted'
            WHEN 2 THEN 'Read Committed'
            WHEN 3 THEN 'Repeatable'
            WHEN 4 THEN 'Serializable'
            WHEN 5 THEN 'Snapshot'
        END
    ,ConnectionWrites   = con.num_writes
    ,ConnectionReads    = con.num_reads
    ,ClientAddress      = con.client_net_address
    ,Authentication     = con.auth_scheme
    ,DatetimeSnapshot   = GETDATE()
FROM sys.dm_exec_requests er
LEFT JOIN sys.dm_exec_sessions ses
ON ses.session_id = er.session_id
LEFT JOIN sys.dm_exec_connections con
ON con.session_id = ses.session_id
CROSS APPLY sys.dm_exec_sql_text(er.sql_handle) AS qt
OUTER APPLY
(
    SELECT execution_count = MAX(cp.usecounts)
    FROM sys.dm_exec_cached_plans cp
    WHERE cp.plan_handle = er.plan_handle
) ec
OUTER APPLY
(
    SELECT
        lead_blocker = 1
    FROM master.dbo.sysprocesses sp
    WHERE sp.spid IN (SELECT blocked FROM master.dbo.sysprocesses)
    AND sp.blocked = 0
    AND sp.spid = er.session_id
) lb
ORDER BY
    er.blocking_session_id DESC,
    er.logical_reads + er.reads DESC,
    er.session_id

END

http://sqlserverplanet.com/dba/a-better-sp_who2-using-dmvs-sp_who3

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