Performance Tuning with SQL Server Dynamic Management Views

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Chapter 4: Transactions
If, from a second tab in SSMS, we now run a second query, shown in Listing 4.4 (having
neither committed nor rolled back the query in Listing 4.2), we'll introduce some blocking
in the AdventureWorks database.
SELECT *
FROM [Production].[ProductCategory] ;
Listing 4.4: A simple query against the ProductCategory table, which will be blocked.
We'll present a more detailed script for detecting blocking in the next section, but the one
in Listing 4.5 demonstrates the basic pattern for joining to the execution-related DMOs
to find out which sessions are involved in blocking, which login "owns" these sessions,
and what SQL statements they are executing.
SELECT DTL.[request_session_id] AS [session_id] ,
DB_NAME(DTL.[resource_database_id]) AS [Database] ,
DTL.resource_type ,
CASE WHEN DTL.resource_type IN ( 'DATABASE', 'FILE', 'METADATA' )
THEN DTL.resource_type
WHEN DTL.resource_type = 'OBJECT'
THEN OBJECT_NAME(DTL.resource_associated_entity_id,
DTL.[resource_database_id])
WHEN DTL.resource_type IN ( 'KEY', 'PAGE', 'RID' )
THEN ( SELECT OBJECT_NAME([object_id])
FROM sys.partitions
WHERE sys.partitions.hobt_id =
DTL.resource_associated_entity_id
)
ELSE 'Unidentified'
END AS [Parent Object] ,
DTL.request_mode AS [Lock Type] ,
DTL.request_status AS [Request Status] ,
DER.[blocking_session_id] ,
DES.[login_name] ,
CASE DTL.request_lifetime
WHEN 0 THEN DEST_R.TEXT
ELSE DEST_C.TEXT