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. A Cassandra database cluster had switched to Ubuntu and noticed write latency increased by over 30%. How would you _time_ time?

Speed 126

Speed Java AWS Virtualization 126

Percona

JANUARY 14, 2019

What if we use ClickHouse (which is a columnar analytical database) as our main datastore? Well, typically, an analytical database is not a replacement for a transactional or key/value datastore. Although such databases can be very efficient with counts and averages, some queries will be slow or simply non existent. Text search.

Database 40

Database Analytics Blockchain Healthcare 40

SQL Performance

MARCH 17, 2020

Back in 2014, I wrote an article called Performance Tuning the Whole Query Plan. I will be using the 50GB Stack Overflow 2013 database , but any large table with a low number of distinct values would do. The Stack Overflow 2013 database comes without nonclustered indexes to minimize download time. Test Environment.

Servers 86

Servers Tuning Database Efficiency 86

SQL Performance

OCTOBER 29, 2019

In order to use Query Store and Extended Events, you have to configure them in advance – either enabling Query Store for your database(s), or setting up an XE session and starting it. DMV data is always available, so very often it's the easiest method to get a quick first look at query performance. total_worker_time / qs. ORDER BY qs.

C++ 74

C++ Database Servers Tuning 74

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. A Cassandra database cluster had switched to Ubuntu and noticed write latency increased by over 30%. How would you _time_ time?

Speed 40

Speed Java AWS Virtualization 40

SQL Performance

MAY 7, 2019

Back in 2014, I started a series of blog posts here to talk about specific wait types and what they do and don’t mean. These threads are created when SQL Server starts, depending on the number of processor cores available for SQL Server to use. If you’re reading this and thinking “what is he talking about?” then this post is for you.

Servers 40

Servers Azure Metrics Tuning 40

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). This can make it difficult to draw sound performance-tuning conclusions. The orange producer times may be long due to CXPACKET waits.

Servers 95

Servers Tuning Architecture Processing 95