2. How SQL Server works ?!
• SQL Server OS
– Schedulers
– Workers
Lists to which workers can be assigned:
worker
waiter
runnable
I/O
timer
3. WAITS – What are they ?!
• SQL Server 2000
– DBCC SQLPERF
– ”sysprocesses” system view (waittype column)
• SQL Server 2005 - DMVs
– sys.dm_os_wait_stats – wait statistics
– sys.dm_os_waiting_tasks – task-level wait information
• SQL Server 2008
– new waits
– Solve the problem with fine-grained analysis of wait statistics in SQL Server 2005
4. Types of WAITS
• Resource waits
• Queue waits
• External waits
A SQL Server worker thread is not considered to be waiting if any of the
following is true:
• A resource becomes available.
• A queue is nonempty.
• An external process finishes.