What are statistics and why should the developer care?

2022

TL; DR

A quick dive into how queries get analyzed and optimized by the SQL Server engine. You'll learn about statistics, density and cardinality, why they are important, and the techniques to keep them up to date, to achieve optimal query plans.

Session Details

Imagine you're a developer in a small shop, and you experience some degradation of performance in your business-critical ERP system, literally over the weekend. So you are tasked with bringing back that performance, because somehow you also inherited the "accidental DBA " role. Hardware is OK, the network is OK, and your application hasn't changed lately, either. Now what? Let me take you for a quick dive into how your queries get analyzed and optimized by the SQL Server engine. You'll learn about statistics (also about density and cardinality), why they are important, ways to explore them and the techniques to keep them up to date, in order to achieve optimal query plans.

3 things you'll get out of this session

Thomas Hütter's other proposed sessions for 2026

Window functions in SQL Server - brush up your skills - 2026

Thomas Hütter's previous sessions

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An R primer for SQL folks

A walk-through on what is possible analyzing your data with the "R" language.

50 ways to show your data

„A picture is worth a thousand words“ - compelling visualizations beyond the usual bar, line or scatter plots, produced with the help of the ggplot2 package and friends.