Posts by Kendra Little

Kendra Little

167 posts

My goal is for you to understand your SQL Server’s behavior– and learn how to change it. When I’m not figuring out the solutions to your database problems, you’ll find me at user group meetings in Portland, Oregon. I also love to draw.

The Hard Truth About Patching SQL Server Availability Groups (Hotfixes, Cumulative Updates, and Service Packs)

Last Updated September 21, 2017

Kendra Little

Always On Availability Groups, Breaking News

Whoa, be careful with that fix As a DBA, you’re responsible for identifying necessary updates to keep your SQL Servers healthy. Your business may have some mandates about the frequency of patches, but even if they don’t, you have a duty to look out for Cumulative Updates, Service Packs, and out of band hotfixes that can prevent…

Failing over an Asynchronous Mirror in SQL Server (video)

Last Updated February 9, 2017

Kendra Little

Database Mirroring

Will a long running open transaction block you from changing to synchronous mode and failing over to your SQL Server database mirror? Join Kendra to test performing a planned failover from an asynchronous database mirror. Brent Says: Often, when I’m working with developers, they’re totally surprised that SQL Server’s failover methods all break in-flight transactions. No matter…

Reporting From a Log Shipping Secondary in STANDBY mode

Last Updated February 13, 2017

Kendra Little

Log Shipping, SQL Server

You can build a lot with simple tools. Carefully. I’m a fan of SQL Server’s transaction log shipping. It works in Standard Edition, it’s relatively simple to set up, and you can even make your log shipping secondary readable using STANDBY mode. I’ve worked with some pretty cool, complex log shipping environments over the years.…

How to Use SQL Server’s Dedicated Admin Connection (DAC) – Video

Last Updated January 14, 2015

Kendra Little

SQL Server

You may have heard that there’s a secret back door into your SQL Server– but have you enabled access to it properly? Do you know when you might need to use it, and how you can connect? Kendra Little explains why the Dedicated Admin Connection (or “DAC”) is so important and how to configure remote…

Testing ALTER INDEX REBUILD with WAIT_AT_LOW_PRIORITY in SQL Server 2014

Last Updated February 13, 2017

Kendra Little

Index Maintenance, Locking, Blocking, and Isolation Levels, SQL Server

One of the blocking scenarios I find most interesting is related to online index rebuilds. Index rebuilds are only mostly online. In order to complete they need a very high level of lock: a schema modification lock (SCH-M). Here’s one way this can become a big problem: An online index rebuild starts against a large index A…

Eight Things A DBA Should Always Do with SQL Server

Last Updated January 4, 2015

Kendra Little

SQL Server

I started tweeting various single-words you could start an argument with the other day. I really liked this suggestion from @SQL_Kiwi: @Kendra_Little One word ways to start an argument: always (or never) — Paul White (@SQL_Kiwi) December 31, 2014 It got me thinking. What are the things that I would say you a DBA should…

Does Updating Statistics Cause a Recompile if No Data Has Changed?

Last Updated August 7, 2018

Kendra Little

SQL Server, Statistics

tl;dr — Not necessarily. One of our students asked me a great question: if you update statistics on every table in the database, is that effectively the same as dumping the procedure cache on the instance? Will every execution plan have to be recompiled the next time it is run? I thought it was a great question and it…

Tip for Learning Extended Events – Use “New Session” (Not “New Session Wizard”)

Last Updated December 30, 2014

Kendra Little

SQL Server

Extended Events have become one of my favorite tools for learning about tuning SQL Server. Whenever I wonder how something works, I can fire up a test instance and play around with XEvents. It’s always interesting, and at least 5% of the time I end up learning what I intended. Not everything is sunshine and rainbows. Finding…

What is the PREEMPTIVE_DEBUG Wait in SQL Server?

Last Updated December 24, 2014

Kendra Little

SQL Server

Recently we got an email asking for help from a DBA who was concerned about a high percentage of the PREEMPTIVE_DEBUG wait on a SQL Server. They were investigating poor performance and had searched the internet high and low and not found information on what this wait means. They were stumped. What to Do When You Find an Unusual…

Read Committed Snapshot Isolation: Writers Block Writers (RCSI)

Last Updated February 13, 2017

Kendra Little

Locking, Blocking, and Isolation Levels, SQL Server

When learning how Read Committed Snapshot Isolation works in SQL Server, it can be a little tricky to understand how writes behave. The basic way I remember this is “Readers don’t block writers, writers don’t block readers, but writers still block writers.” But that’s not so easy to understand. Let’s take a look at a simple test…

Whitespace, Comments, and Forced Parameterization in SQL Server

Last Updated December 22, 2014

Kendra Little

SQL Server

A question came up in our company chat room the other day: does the forced parameterization database setting help with plan cache bloat caused by dynamic comments or whitespace? I love the topic of parameterization in SQL Server, probably because it’s one of those things that’s really pretty weird (but seems like it’d be straightforward). So…

The Most Confusing Words, Phrases, and Acronyms in SQL Server

Last Updated February 13, 2017

Kendra Little

Humor

Words are hard. Acronyms are even harder. Here’s the words that give me the most trouble when talking to people about SQL Server. And thanks to all my Twitter friends quoted here for their suggestions! Replication “I have a question about replication…” “Which kind? Transactional? Merge? Peer to Peer?” “Availability Groups.” Technically, the word “replication”…

Rebuild or Reorganize? How to Set Up Index Maintenance in SQL Server (video)

Last Updated December 3, 2014

Kendra Little

SQL Server

Index maintenance is confusing. Should you use maintenance plans or customized SQL Agent jobs? Join Kendra to learn the difference between index ‘rebuild’ and ‘reorganize’ commands, and how to avoid the pitfalls of maintenance plans in SQL Server. Interested in trying out sp_BlitzTrace™ yourself? Download it in our free SQL Server download pack. You can…

Did You Give SQL Server 2012 Standard Edition Enough Memory?

Last Updated February 9, 2017

Kendra Little

Licensing

Who needs disk when you have memory? It’s a bummer that SQL Server 2012 Standard Edition only allows you 64GB of memory. And it’s good news that the limit goes up to 128GB of memory in SQL Server 2014. But are you getting as much memory as you can out of Standard Edition? Check out…

Transactional Replication Architecture: Isolating Subscriber Tables

Last Updated February 9, 2017

Kendra Little

Replication

The best part about transactional replication is that it’s flexible. And the worst thing about transactional replication is that it’s flexible. A poor replication configuration will cause you performance pains and increase your risks of development and administrative errors. Here’s one important design principle: isolate your replication subscriber tables from one another, and from non-subscriber tables.…

How many CPUs is my parallel query using in SQL Server?

Last Updated May 4, 2018

Kendra Little

Execution Plans

Parallelism can be confusing. A single query can have multiple operators that run at the same time. Each of these operators may decide to use multiple threads. You set SQL Server’s “max degree of parallelism” to control the number of processors that can be used, but it’s not immediately obvious what this means. Does this setting…

SQL Server’s Cost Threshold for Parallelism

Last Updated November 20, 2014

Kendra Little

SQL Server

“Should a query get to use more than one CPU core?” That’s an important question for your SQL Server. If you’re not sure what parallelism is, get started by exploring the mysteries of CXPACKET with Brent. He’ll introduce you to the the setting, ‘Cost Threshold for Parallelism’. Let’s test Cost Threshold for Parallelism I generate an estimated…

What Changed Our Career Trajectories?

Last Updated October 17, 2014

Kendra Little

SQL Server

Jeremiah has coffee at the PASS Summit We’re a group of specialists and teachers here at Brent Ozar Unlimited. But we didn’t start that way– we started out as engineers and developers. So what was it that changed our career trajectories? For each of us, we had a lot of smaller factors along the way, but…

What to Expect at the PASS Summit and SQL Intersections (Video)

Last Updated October 27, 2014

Kendra Little

SQL Server

If you’re going to a SQL conference for the first time, join us to learn how things work. We’ll share what happens when you walk in the door for the first time, where to go after hours, what to bring, and what NOT to bring.

Why You Shouldn’t Use SQL Server’s Activity Monitor

Last Updated January 18, 2019

Kendra Little

sp_BlitzFirst, SQL Server

I love free tools. I also love analyzing SQL Server’s wait statistics. But I’m not a fan of Activity Monitor, a free tool in SQL Server Management studio, which helps you look at wait stats. Activity Monitor just doesn’t give you the whole truth. I fired up a workload with HammerDB against a test SQL Server 2014 instance.…