One of our SQL Server workloads runs many concurrent parallel queries on a possibly already busy server. Other work occurring on the server can have dramatic effects on parallel query runtimes. One way to improve scalability of parallel query runtimes …
Category: Parallelism
Detecting Query Weirdness In Query Store
Let’s Have Fun
I got asked recently if there’s a way to find parallel queries that are potentially skewed.
One thing that you’ll see quite often is that duration and cpu time aren’t much different. For parallel queries, it should …
My Favorite Cursors
Cursory
…
An Unfortunate Side Effect Of OUTPUT
Put Out
I see people using OUTPUT to audit modifications from time to time, often because “triggers are bad” or “triggers are slow”.
Well, sometimes, sure. But using OUTPUT can be a downer, too.
Let’s look at how.
A Process
…Quickly Detecting CPU and Memory Pressure On A SQL Server
Options Ahoy
There are lots of great options out there for figuring out what’s happening on a server. If you’re the kind of person still running sp_who, or sp_who2, or sp_who8045, it’s time to stop.
You’ve got much better options, …
Parallelism And Table Variables
Well, huh
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Does Parallelism Change Memory Grants?
This was originally posted as an answer by me here, I’m re-posting it locally for posterity
Sup?
For SQL Server queries that require additional memory, grants are derived for serial plans. If a parallel plan is explored and chosen, …
Why Spills In Parallel Plans Can Be Weird
Go Along, Get Along
This is a somewhat complicated topic. There’s not a great TL;DR here, but I don’t want anyone to walk away from this post thinking that parallelism or indexes are “bad”.
What I do want to show …
Why Does My Serial Query Have Parallel Waits?
Harkening
In dramatic fashion, I’m revisiting something from this post about stats updates.
It’s a quick post, because uh… Well. Pick a reason.
Get In Gear
Follow along as I repeat all the steps in the linked post to:
- Load