SQL Performance

MARCH 17, 2020

Back in 2014, I wrote an article called Performance Tuning the Whole Query Plan. This follow-up post revisits the question for SQL Server 2019, using a larger number of rows. It has 32GB RAM, with 24GB available to the SQL Server 2019 instance. Test Environment. The cost threshold for parallelism is set to 50.

Servers 86

Servers Tuning Database Efficiency 86

SQL Performance

JUNE 21, 2019

I've been teaching and writing about common SQL Server mistakes for many years. This article will expand on my previous article and point out how these apply to SQL Server , Azure SQL Database , and Azure SQL Managed Instance. SQL Server Agent alerts. This situation applies to on-premises SQL Server and IaaS. Statistics.

Servers 49

Servers Azure Hardware Database 49

Brendan Gregg

SEPTEMBER 25, 2021

These strange questions came to the fore back in 2014 when Netflix was switching services from CentOS Linux to Ubuntu, and I helped debug several weird performance issues including one I'll describe here. This server is spending about a third of its CPU cycles just checking the time! How long does it take to read the time?

Speed 126

Speed Java AWS Virtualization 126

Brendan Gregg

SEPTEMBER 25, 2021

These strange questions came to the fore back in 2014 when Netflix was switching services from CentOS Linux to Ubuntu, and I helped debug several weird performance issues including one I'll describe here. This server is spending about a third of its CPU cycles just checking the time! How long does it take to read the time?

Speed 40

Speed Java AWS Virtualization 40

Brendan Gregg

SEPTEMBER 5, 2017

Linux has been adding tracing technologies over the years: kprobes (kernel dynamic tracing), uprobes (user-level dynamic tracing), tracepoints (static tracing), and perf_events (profiling and hardware counters). Oracle VM Server is based on Xen. Outside of EC2, many other providers are deploying on KVM.

Virtualization 76

Virtualization AWS Engineering Hardware 76

SQL Performance

MARCH 8, 2021

SQL Server 2014 SP2 and later produce runtime (“actual”) execution plans that can include elapsed time and CPU usage for each execution plan operator (see KB3170113 and this blog post by Pedro Lopes). SQL Server makes some timing adjustments in parallel plans to promote consistency, but they are not perfectly implemented.

Servers 95

Servers Tuning Architecture Processing 95