Wait Stats

When Did My Azure SQL Database Server Restart?

Last Updated April 8, 2020

In Azure SQL Database, no one can hear you scream query common system objects that tell you when a restart happened. You don’t get the access you need to sys.dm_os_sys_info, sys.dm_exec_sessions, sys.traces, or sys.databases. The closest I’ve been able to get is to query sys.dm_os_wait_stats for several common wait types that seem to correspond with…

“It’s Slow” Is Not A Metric

Last Updated February 13, 2017

Jes Schultz

Wait Stats

When I start a SQL Server Critical Care with a client, the first thing I ask is, “What is your #1 pain point? Where does it hurt?” The answer I hear most often is, “The server is too slow”. I’m a runner. If I was able to run a 5K race at an 8:30 per…

T-SQL Tuesday: Stop Tuning with Wait Stats Percentages

Last Updated July 3, 2018

Brent Ozar

SQL Server, Wait Stats

For this month’s T-SQL Tuesday topic, Michael J. Swart told us to argue against a popular opinion, and man, is that right up my alley. I’ve told you to stop worrying about index fragmentation, stop backing up your logs once an hour, and to stop running $14k of licensing on $3k of hardware. You’re probably checking…

What is the CXPACKET Wait Type, and How Do You Reduce It?

Last Updated August 13, 2021

Brent Ozar

SQL Server, Wait Stats

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When you query sys.dm_os_wait_stats, or check your waits with sp_Blitz® or sp_BlitzFirst®, one of your biggest wait types is probably CXPACKET. Let’s talk about what’s really going on. Our SQL Server Stand-In: a Class. Who wants to help me scan the sales table? Pretend that you’re a schoolteacher in a classroom with a couple dozen students.…

Using SQL Server Without Monitoring Software is Like Overdriving Your Headlights

Last Updated July 28, 2021

Brent Ozar

Monitoring, Wait Stats

The strength of your car’s headlights, the speed of your reactions, and the power of your brakes determine how fast you can drive safely at night. Likewise, in SQL Server, we need to see down the road before disaster strikes, and react as quickly as possible.

The Ozar Family Tradition of Performance Monitoring

Last Updated February 13, 2017

Brent Ozar

Monitoring, Wait Stats

When my Grandpa Ozar wanted to find out if his 10 megabyte 5.25″ hard drive was responding fast enough to handle his database loads, he monitored the Perfmon counter Physical Disk: Disk Queue Length.

Things have changed since Grandpa’s time, though, and now it’s time to learn a new performance tuning trick – SQL Server waits.