Statistics are one of the most powerful — and most misunderstood — components of the SQL Server query optimizer. They drive cardinality estimation, influence join strategies, shape memory grants, and ultimately determine whether a query runs in milliseconds or minutes. When they’re fresh and accurate, statistics make SQL Server look brilliant. When they’re stale, incomplete, or misleading, they can bring even the best‑designed systems to their knees.
This session takes you deep into the world of SQL Server statistics: what they are, how they work, and why they matter. We’ll explore histogram structures, density vectors, cardinality estimation models, and how SQL Server uses statistics to choose execution plans. You’ll learn the difference between auto‑created and user‑created statistics, when filtered statistics shine, and how ascending keys, skewed data, and parameter sensitivity can sabotage even the most carefully indexed workloads.

Intermediate to Advanced. Attendees should have a solid understanding of indexing, query plans, and basic performance troubleshooting. No prior deep knowledge of histogram internals or cardinality estimation models is required — these concepts will be introduced and demystified during the session