So far, we’ve covered how to find your server’s most resource-intensive queries, and you’ve opened their execution plans to figure out where the estimates vs actuals go wrong. Now, learn what T-SQL anti-patterns cause the estimates to go wrong. Demo Script Transact-SQL /* Fundamentals of Query Tuning: Common T-SQL Anti-Patterns v1.3 – 2023-11-05 https://www.brentozar.com/go/queryfund This…
Generally, when a query plan operator’s estimated number of rows is vaguely similar to the actual number of rows, SQL Server had a pretty good idea of how much work would be required for that part of the query, and it built an appropriate plan. It may not be a fast plan – for example, maybe…
When you look at the arrows on an actual plan, what do the arrow sizes mean? When you see the list of wait stats, they’re accurate, right? Buckle up and prepare to be disappointed – a lot of what you see in a query plan just flat out isn’t true. Here is the demo script:…
