Matthew McGiffen DBA

Viewing the Statistics Objects Used to Create an Execution Plan

• by Matthew McGiffen

• Matthew McGiffen DBA

Use trace flag 8666 to view the statistics objects that the optimizer used to generate your execution plan.

2021-03-01

9 reads

Automatic Sample Sizes for Statistics Updates

• by Matthew McGiffen

• Matthew McGiffen DBA

Looking at how SQL Server samples your data when doing auto-stats updates. Part of a series on understanding statistics, to help you achieve optimal performance of your queries on...

2021-03-02 (first published: 2021-02-24)

133 reads

Manually updating Statistics

• by Matthew McGiffen

• Matthew McGiffen DBA

Having up to date statistics is vital for getting the best performance out of your queries. Even though SQL Server automatically updates statistics in the background for you, you...

2021-02-16

198 reads

Book Review: Learn dbatools in a Month of Lunches

• by Matthew McGiffen

• Matthew McGiffen DBA

If you work in the world of SQL Server you’ve almost certainly heard of dbatools. For those who haven’t, it’s an open source PowerShell module for automating literally hundreds...

2021-02-15

18 reads

Reminder: SQL Server Agent and the clocks going forward

• by Matthew McGiffen

• Matthew McGiffen DBA

For most of us in the Northern Hemisphere the clocks go foward next month and we get to look forward to longer, sunnier evenings. This post is a reminder...

2021-02-17 (first published: 2021-02-10)

417 reads

Statistics and the Ascending Key Problem

• by Matthew McGiffen

• Matthew McGiffen DBA

I’ve mentioned previously how not having up to date statistics can cause problems in query performance. This post looks at something called the Ascending Key Problem which can badly...

2021-02-09

156 reads

What are Statistics in SQL Server?

• by Matthew McGiffen

• Matthew McGiffen DBA

Statistics are vitally important in allowing SQL Server to find the most efficient way to execute your queries. In this post we learn more about them, what they are...

2021-02-01

348 reads

Rowcount estimates when there are no Statistics

• by Matthew McGiffen

• Matthew McGiffen DBA

When you don't have statistics, what does SQL use to calculate the estimated number of rows?

2021-02-04 (first published: 2021-01-26)

272 reads

When do Statistics get updated?

• by Matthew McGiffen

• Matthew McGiffen DBA

Statistics objects are important for allowing the SQL Server Optimizer to make good estimates and form efficient execution plans. Related to that it's useful for us to understand when...

2021-01-25 (first published: 2021-01-18)

465 reads

How does Query Store capture cross database queries?

• by Matthew McGiffen

• Matthew McGiffen DBA

Query Store is a configuration that is enabled per database, and the plans and stats for queries executed in that database are stored in the database itself. So what...

2021-01-18 (first published: 2021-01-11)

440 reads