Development

Home
Development

Simon Sabin’s talk on query performance

Last Updated March 10, 2021

At #SQLbits, Simon Sabin (Twitter) talked about car crash queries: queries that suddenly have bad performance out of nowhere, yet if you copy/paste them into SQL Server Management Studio, they run quickly. The culprit is often parameter sniffing: the engine looks at the query and builds a plan, but if the parameters in the WHERE…

Book Review: SQL Server 2008 Query Performance Tuning Distilled

Last Updated February 13, 2017

Brent Ozar

Book Reviews, Execution Plans

My gauge of an amazing book is simple: if I’ve got a question, and I reach for the book BEFORE I search the web, then it’s an amazing book. Several times in the last two weeks, I reached for this book first.

Getting Help With A Slow Query

Last Updated October 21, 2017

Brent Ozar

Execution Plans

StackOverflow users often ask, “I’ve got this query that runs slow – can you help?” Here’s a few tips to get better, faster answers, including getting the execution plan and relevant Perfmon data.

SQL Server load testing: synchronized tests versus random ones

Last Updated February 14, 2017

Brent Ozar

Load Testing

Our QA department uses Mercury TestDirector to do load testing of our .NET web apps. The basic idea is that TestDirector runs through a set of URLs to load test an application, and it can gradually scale up the number of simultaneous sessions until the datacenter is filled with smoke. When the fire alarms go…