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.

Q: Can High MaxDOP make a query SLOWER?

Last Updated December 21, 2013

Kendra Little

SQL Server

Answer: Yep, sometimes it can. I used to think that higher degrees of parallelism followed a law of diminishing returns– you could add more threads, but the benefits would taper off. But it’s a bit more complicated than that. Microsoft’s recommendation to be careful when setting maxdop to values over 8 is a warning worth heeding.…

RECOMPILE Hints and Execution Plan Caching

Last Updated April 2, 2021

Kendra Little

Execution Plans, Parameter Sniffing

The DBA version of an XKCD classic. When you identify that parameter sniffing is a problem, you need to test whether implementing ‘recompile’ hints will help plan quality. (Not sure what parameter sniffing is? Learn from this blog post or this 50 minute free video.) You must decide: what hint or command do you use,…

How to Write a Killer SQL Server Job Description

Last Updated February 12, 2017

Kendra Little

Professional Development

Hiring managers often feel like they’re trying to find a mythical creature On September 24, we published a blog post that we were looking for a new employee. We didn’t advertise on any job listing sites (even though there are some really good ones out there). We tweeted about it a few times, but most…

3 Signs Your DBA Skills Need an Upgrade (video)

Last Updated October 12, 2013

Kendra Little

SQL Server

You’re a Database Administrator who gets the job done day in and day out– but you’re worried that maybe your skills aren’t quite up to par. How do you know if you’ve fallen behind? Join Kendra in this free webcast for a simple test to learn if your DBA knives are as sharp as they…

How Much is Offline During an Index Rebuild?

Last Updated February 16, 2017

Kendra Little

Index Maintenance

Kendra with her Not-A-SAN This question came up in the pre-show chat for our weekly webcast: when you rebuild a nonclustered index offline, does it impact only the nonclustered index? Or does it impact the entire table? Showing is more fun than telling! Let’s take a look. First I restore AdventureWorks to slow storage Sometimes…

Make SQL Apps Go Faster – Only 60 Seats Left!

Last Updated February 12, 2017

Kendra Little

#SQLPass

In just a few weeks, Brent, Jes and I will be giving a full day pre-conference session at the SQLPASS 2013 Conference in Charlotte, North Carolina. Our pre-conference will be Tuesday, October 15, 2013. There’s only a few seats left! This pre-con’s going to be killer– we’ve got 240 folks registered and ready to learn.…

Missed Connection: Employer Seeking Employee

Last Updated February 12, 2017

Kendra Little

Company News, SQL Server

You were helping a sysadmin understand the details of a request for a new virtual server. You whiteboarded a diagram to show how SQL Server uses memory. You got so excited when the sysadmin asked a hard question that you spilled coffee everywhere. We were tuning queries on a video conference with developers from That…

You Can’t Kill Transactional Replication

Last Updated February 9, 2017

Kendra Little

Replication

181

Repli-Roach If SQL Server’s Transactional Replication was an animal, it would be a cockroach. It’s not pretty, but it’s resourceful and strong. Once you get even a small amount of replication in your environment it starts spreading everywhere. And if it gets out of control– well, in that case you’ve got no choice but to…

Rebuild or Reorganize: SQL Server Index Maintenance

Last Updated February 13, 2017

Kendra Little

Index Maintenance, SQL Server

109

Index maintenance compacts a structure *and* changes physical order– both can be important! Editors Note: this post was updated in June 2014 to link to an online index rebuild bug that can cause corruption. Once up on a time, there was a database server with 500GB of data and a heavy read workload of dynamic…

Query Plans: Memory Grants and High Row Estimates

Last Updated January 8, 2019

Kendra Little

Execution Plans, Memory Grants, SQL Server

SQL Server needs to have a reasonably correct estimate of how many rows your query is going to handle. If it doesn’t, things can go terribly, terribly wrong. Most often, the problem is that SQL Server under estimates its work. In this case, the query optimizer thinks it has just a little bit of work…

Introduction to SQL Server Failover Clusters (video)

Last Updated February 9, 2017

Kendra Little

Clustering, SQL Server

You’d love to know how to make your SQL Servers more highly available, but you’re just not sure what “clustering” is all about. We can help! In this 30 minute video Kendra Little shows you how failover clusters make your SQL Servers easier to manage. She uses diagrams and drawings to teach you the strengths…

The Stages of Performance Tuning

Last Updated August 18, 2013

Kendra Little

SQL Server

Performance tuning is a weird art to learn, because you do it in public. Sure, you may puzzle over a technical problem at your desk or revise code on your own– but when it comes to really tuning hard problems, 99% of the time you’re doing it with other people. That’s the nature of real…

How to Master SQL Server Index Tuning in One Step

Last Updated August 12, 2013

Kendra Little

SQL Server

I’m going to tell you a secret. Index tuning is complicated, but it’s something you can become great at. You just need to practice it regularly. Here’s that one step: stop thinking index tuning is a problem for Future You. That’s it. Really. If you read this headline and didn’t skip the post, your job…

I’m ThatExcited about ThatConference

Last Updated August 10, 2013

Kendra Little

SQL Server

A peek into my slides for ThatConference I about to head out to a vast waterpark in the Midwest to ThatConference, where I’m going to hang out with 1000 developers, their families, and some wild animals. I’m giving a session Monday called “How to Make Deploying Database Changes Fun Again”. I’ve had a blast distilling everything…

What?! Queries are Failing in My SQL Server?

Last Updated May 2, 2015

Kendra Little

SQL Server

Help is on the way I came across an interesting case recently where queries were failing in a high transaction SQL Server. We knew that queries were occasionally failing with error severity 20 because SQL Server Agent alerts were periodically firing. However, those built in alerts don’t capture exactly what has failed– they just say…

Trivial Optimization and Missing Indexes in SQL Server

Last Updated May 12, 2019

Kendra Little

Indexing, SQL Server

Recently, Jes asked the team an index tuning question: “If a query has an index hint in it, will the optimizer ever suggest a missing index for that query?” I immediately loved the question because I’d never really thought about it before. I typically think of index hints as being a very risky game and…

How to Find ‘Secret Columns’ in Nonclustered Indexes

Last Updated November 16, 2017

Kendra Little

Indexing, sp_BlitzIndex

sp_BlitzIndex® just can’t keep a secret. That’s a feature, not a bug. I wrote sp_BlitzIndex® specifically so that it would rat out some things that SQL Server is doing behind the scenes to secretly help you out– because it’s really better if you know about it. What are secret columns? SQL Server needs a unique…

Optimize for… Mediocre?

Last Updated May 26, 2020

Kendra Little

Parameter Sniffing, SQL Server

Some query hints sound too good to be true. And, unfortunately, usually they aren’t quite as magical as they might seem. Frustration with unpredictable execution times People often learn about parameter sniffing when query execution times stop being predictable. Occasionally you’ll hear about a stored procedure taking much longer than normal, but the next time…

The Index Your Queries will Never Request (A Clustered Index!)

Last Updated April 10, 2017

Kendra Little

Indexing, SQL Server

When it comes to indexes, SQL Server is really helpful. It lets you see what indexes queries are asking for both in execution plans, and missing index dynamic management views (“DMVs”). I like to look at the DMV missing index requests using sp_BlitzIndex®. When you look at missing index requests, it’s always important to remember…

Indexing Wide Keys in SQL Server

Last Updated February 13, 2017

Kendra Little

Indexing, SQL Server

Key length matters in SQL Server indexes. It’s a best practice to keep your index keys as narrow as possible, and SQL Server enforces a maximum key length of 900 bytes on most “normal” clustered and nonclustered indexes. But what happens if you want to optimize the lookup of a wide column? You’re not necessarily…