SQL Puzzle 2: Eight Queens

This puzzle was first proposed in 1848 by a composer of chess puzzles called Max Bezzel and has since spawned...

Manually updating Statistics

Even though SQL Server automatically updates statistics in the background for you, you may find there are times when you...

Think twice before using table variables

T-SQL Tuesday

For T-SQL Tuesday this month Raul Gonzalez has asked us all to blog about lessons learnt the hard way:
http://www.sqldoubleg.com/2017/07/03/tsql2sday-92-lessons-learned-the-hard-way/
My...

Row-count Estimates when there are no Statistics

I was discussing Cardinality Estimation with a colleague recently and the question came up, what cardinality does SQL Server use...

When do Distribution Statistics Get Updated?

Statistics objects are important to us for allowing SQL to make good estimates of the row-counts involved in different parts...

Statistics and Cardinality Estimation

Cardinality
This is a term originally from Mathematics, generally defined as “The number of objects in a given set or grouping”....

Statistics Parser

In the last post we looked at using the STATISTICS IO and STATISTICS TIME commands to measure query performance.
If you’ve...

What’s an “Index” and how do they work?

What is an Index?
We often hear indexes explained using the analogy of an index in the back of a book....

Understanding Keys and Certificates with Always Encrypted

Always Encrypted on SQL 2016 is pretty easy to set up. There’s even a single wizard to guide you through...

Measuring SQL Query Performance

When running workshops on the subject of SQL Query Performance the first question I always ask is how do we measure...