We All Have It
You know those tables, right? The ones where developers went and got lazy or didn’t know any better and decided every string column was going to be gigantic.
They may have read, of course, that SQL …
Category: Spills
When Query Spills Cause tempdb Contention And Performance Issues In SQL Server
Temptables
I was helping a client troubleshoot a scalability issue recently, where during one point in their workload tempdb went out of control.
What was puzzling them was that nothing in the stored procedure did anything with temporary objects, cursors, …
Wait Stats During Exchange Spills In SQL Server Parallel Query Plans
Inorganic
Lots of people say these are rare — and perhaps they are becoming more so — but I still see them with some frequency. That’s not a terribly strong indictment of SQL Server, but that’s not the point of …
Wait Stats During Hash Spills In SQL Server Query Plans
Jam Job
Hash spills are, as we’ll see, sometimes identified by a different wait than sort spills. In small quantities, spills are often not worth bothering with. But when they pile up, they can really cause some severe performance issues.…
Wait Stats During Sort Spills In SQL Server Query Plans
Over Under
Over the next few days, I’m going to look at the wait stats that show up during different types of spills of different sizes. For no reason whatsoever, I’m going to start with sort spills. I’ll also cover …
Signs Your SQL Server Execution Plan Is Lying To You: Spills and Memory Grants
Milky
Going Further
If this is the kind of SQL Server stuff you love learning about, you’ll love my training. I’m offering a 75% discount on to my blog readers if you click from here. I’m also available for …
Signs Your SQL Server Execution Plan Is Lying To You: Exchange Spills
Since They Wanna Know
Going Further
If this is the kind of SQL Server stuff you love learning about, you’ll love my training. I’m offering a 75% discount on to my blog readers if you click from here. I’m …
Why Spills In SQL Server Parallel Plans Can Hurt Performance
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 …
Spills Week: How Exchange Spills In Parallel Query Plans Crush Query Performance
Many Have Entered, Few Have Left
For some background on Exchange Spills, check out this Great Post™ by Joe.
The root of this demo was trying to show people silly things about CTEs, how TOP can fence things off…
Spills Week: How Hash Join Spills Hurt SQL Server Query Performance
Thirsty Thursday
If you’ve made it this far, you’ve learned a few things:
- Not all spills are worth trying to fix
- The more columns you select, the worse spills get
- The larger your string datatypes are, the worse spills get