Lately I’ve been doing some exploratory performance testing on Azure SQL Managed Instances in preparation for a migration to that platform. This blog post documents some storage testing results and may even have practical advice near the end. All testing …
Author: Joe Obbish
What’s in your SQL Server error log?
This is my 50th blog post! I’m going to do something a bit special.
The Error Log
I’ve found the SQL Server error log to be slightly underrated as a source of useful information for how your SQL Server instance …
Quick SQL Server CPU Comparison Tests
Sometimes I have a need to run a quick CPU comparison test between two different SQL Server instances. For example, I might be switching from old hardware to new hardware and I want to immediately see a faster query to …
Columnstore Loading on Eight Socket Servers
I had a brief opportunity to do SQL Server workload testing on an eight socket server. It didn’t go well.
Sockets
I’ll give an extremely brief introduction to NUMA and sockets because I have a bit more free time these …
The Trillion Row Operator
SQL Server friend and excellent webmaster Mr. Erik C. Darling showed me a query plan gone wrong:
48 billion rows for a single operator is certainly a large number for most workloads. I ended up completely missing the point and …
Using Exchange Demand Partitioning to Improve Parallel Query Scalability
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 …
Trace flag 3656 is not sufficient for symbol resolution on SQL Server 2019
You may have noticed that TF 3656 appears to no longer work in SQL Server 2019 RC1. Symbols are not resolved in Extended Events event data even with that trace flag enabled. Trace flag 2592 must also be enabled to …
What is the PVS_PREALLOCATE wait type?
I was workload testing on SQL Server 2019 RC1 when I ran into a wait type I’d never noticed before: PVS_PREALLOCATE. Wait seconds per second was about 2.5 which was pretty high for this workload. Based on the name it …
Columnstore Precon Details
I thought it could be helpful to go into more detail for what I plan to present at the columnstore precon that’s part of SQL Saturday New York City. Note that everything here is subject to change. I tried …
Thoughts on MAXDOP
Microsoft recently published new guidance on setting server level MAXDOP. I hope to help the community by analyzing the new guidance and offering some of my own thoughts on query parallelism.
Line by line
Documentation is meant to be shared …