Tuesday, December 18, 2012

sp_who and sp_who2 Blocking processes

From
http://stackoverflow.com/questions/2234691/sql-server-filter-output-of-sp-who2 and
http://sqlserverplanet.com/dba/a-better-sp_who2-using-dmvs-sp_who3

With sp_who and sp_who2 we can determine what process is blocking a table for example. We can use the following script to filter out the sp_who2 output:
DECLARE @Table TABLE(
        SPID INT,
        Status VARCHAR(MAX),
        LOGIN VARCHAR(MAX),
        HostName VARCHAR(MAX),
        BlkBy VARCHAR(MAX),
        DBName VARCHAR(MAX),
        Command VARCHAR(MAX),
        CPUTime INT,
        DiskIO INT,
        LastBatch VARCHAR(MAX),
        ProgramName VARCHAR(MAX),
        SPID_1 INT,
        REQUESTID INT
)

INSERT INTO @Table EXEC sp_who2

SELECT  *
FROM    @Table
WHERE ....

Another way is to use a custom sp_who3 sp for this:
CREATE PROCEDURE [dbo].[sp_who3] 

AS
BEGIN

SET TRANSACTION ISOLATION LEVEL READ UNCOMMITTED

SELECT
    SPID                = er.session_id
    ,BlkBy              = er.blocking_session_id      
    ,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         
    ,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)
    ,LastWaitType       = er.last_wait_type
    ,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
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
ORDER BY
    er.blocking_session_id DESC,
    er.logical_reads + er.reads DESC,
    er.session_id
 
END