SOS_SCHEDULER_YIELD wait stats count the moments a query gives up the CPU after its 4 ms turn and waits to get it back. On Night 8 at the Clipboard Diner, every cook steps on and off the burners all night. Learn when this wait is harmless, when it means CPU pressure, and how to find the queries that burn the most CPU.
Parallelism Wait Stats: Tuning MAXDOP and Cost Threshold
Parallelism wait stats drop when two settings fit your server: cost threshold for parallelism decides which queries go parallel, and MAXDOP decides how many threads they get. On Night 7 at the Clipboard Diner, Casey writes two house rules for big parties. Then the kitchen starts learning on its own, the way DOP feedback does in SQL Server 2025 Enterprise.
OUTPUT INTO: Record Old and New Values in One Write
OUTPUT INTO records old and new values during a write, while the transaction determines whether the change survives. Test NULL transitions, unchanged values, rollback and target failures before treating captured rows as committed history.
CXPACKET Wait Stats: What Parallel Waits Mean
CXPACKET wait stats measure the threads of a parallel query waiting on each other. On Night 6 at the Clipboard Diner, a tour bus of forty shows why splitting work helps, and how one overloaded cook holds everyone up. Learn CXPACKET, CXCONSUMER and the two CXSYNC waits, and how to spot skew.
Wait Stats Over Time: Measuring One Time Window
Wait stats over time means measuring the waits of one window, such as your busy hour, instead of reading totals since the last restart. On Night 5 at the Clipboard Diner, Casey photographs the clipboard at 6:00 and at 7:00 and subtracts. Then one script does the same thing with two snapshots of sys.dm_os_wait_stats.
Live Wait Stats: What Is Waiting Right Now
Live wait stats show what every request in SQL Server is waiting on at this moment, and who is in its way. On Night 4 at the Clipboard Diner, the Saturday rush stalls behind a party in booth 7 that isn’t waiting for anything. Then three queries find the waiting tasks, the head blocker and one session’s own waits.
sys.dm_os_wait_stats: Reading the Wait Stats List
sys.dm_os_wait_stats is the running list of every wait SQL Server has recorded since its last restart. On Night 3 at the Clipboard Diner, Casey reads the clipboard at 2 AM and crosses out the sleepers. Then one query filters out the harmless waits and shows the share, the average and the signal part of every wait that matters.