We will see two important case studies where the optimizer is obviously a criminal who has killed the query performance. We will together carefully investigate inside the query optimizer and attempt to understand why often it behaves in the manner which is beyond common sense.

While we investigate our crime scene of poorly running query we will learn come across many unusual and usual suspects like - statistics, query hints, indexes, cardinality, and compatibility.

Just like a true investigator, we will figure out why Query Optimizer is not a criminal but rather a victim of circumstances. Before we end the session, we will have a revelation of the true culprits.

The journey would not be an easy one, join only if you have a keen desire to solve the mystery and learn advanced level concepts of Query Optimizer. 

Presented by Pinal Dave at SQLBits 2020