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Finding Distinct Values Quickly

SQL Performance

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. I will be using the 50GB Stack Overflow 2013 database , but any large table with a low number of distinct values would do. Test Environment.

Servers 86
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Analyzing "death by a thousand cuts" workloads

SQL Performance

There are multiple methods to look at poorly performing queries in SQL Server, notably Query Store, Extended Events, and dynamic management views (DMVs). 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.

C++ 74
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Common SQL Server Mishaps

SQL Performance

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.

Servers 49
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The Speed of Time

Brendan Gregg

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
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The Speed of Time

Brendan Gregg

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
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Understanding Execution Plan Operator Timings

SQL Performance

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
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Real-Real-World Programming with ChatGPT

O'Reilly

To provide some coherence to the music, I decided to use Taylor Swift songs since her discography covers the time span of most papers that I typically read: Her main albums were released in 2006, 2008, 2010, 2012, 2014, 2017, 2019, 2020, and 2022. This choice also inspired me to call my project Swift Papers.