28Feb 2017 by Grant Fritchey 19 Comments

Determining the Cost Threshold for Parallelism

SQL Server, SQL Server 2016
In the previous post, I showed how you can get full listings of your execution plan costs. Knowing what the values you're dealing with for the estimated costs on your execution plans can help you determine what the Cost Threshold on your system should be. However, we don't want to just take the average and use that. You need to understand the data you're looking at. Let's explore this just a little using R. Mean, Median, Range and Standard Deviation I've used the queries in the previous blog post to generate a full listing of costs for my plans. With that, I can start to query the information. Here's how I could use R to begin to explore the data: library("RODBC", lib.loc="~/R/win-library/3.2") query <- "SELECT * FROM dbo.QueryCost;" dbhandle <-…
Read More
27Feb 2017 by Grant Fritchey 4 Comments

SQL Clone

Tools
Today is the launch of SQL Clone, a great new tool that helps you quickly and easily provision SQL Server databases for development and testing. Oh god, that sounds like marketing speak. To heck with that. Let me tell you why I'm so excited about SQL Clone and why I think you're going to be excited too. Once Upon a Time... Almost two years ago one of the developers here at Redgate called me over. He wanted to show off this neat trick he'd figured out. What I saw was a good-sized database, about 200gb, created on his local instance of SQL Server in about 10 seconds. Now, that's fast. Further, he showed me the files and disk space on his machine, and it was only taking up a few…
Read More
24Feb 2017 by Grant Fritchey 12 Comments

I Don’t Understand

Professional Development
I suspect this may make a few people angry, but I felt the need to share. I was recently asked to go through my contacts and put together calls with some technologists for a series of discussions. OK. I thought about what we'd need, compared it to a mental list of people and what I know about their work in my head and started sending emails. I got in touch with people. Everyone was interested in helping out. It was a win. Later... Well, I talked yesterday about reading that blog post by Susan J. Fowler and the confusion it caused. I just don't understand it. Further, I don't understand it on two levels. Level 1 Acknowledging that I'm the most evil, privileged individual on the planet, cis-gendered white male,…
Read More
23Feb 2017 by Grant Fritchey 17 Comments

Confusion of An Old Technologist

Professional Development
As someone who still actively pursues a career in technology, I'm a little on the older side. I got started in tech when a lot of the people I know were still in elementary school. So please understand that when I write the rest of this little... rant. I read the blog post by Susan J. Fowler the day it was posted. I'm not sure where I found it. It's been running around and around in my head ever since, so I'm finally going to write a couple of posts on this. Let's Start With Age There's at least an implication that with age comes wisdom. Well, I'm living proof that's total BS. However, I will agree that with age comes perspective. The modern age has its problems. I've had…
Read More
20Feb 2017 by Grant Fritchey 12 Comments

Estimated Costs of All Queries

SQL Server, SQL Server 2016
One question constantly comes up; What should the Cost Threshold for Parallelism be? The default value of 5 is pretty universally denigrated (well, not by Microsoft, but by most everyone else). However, what value should you set yours to? What Do Your Plans Cost? I have a question right back at you. What do your plans currently cost? Let's say, for argument's sake, that all your plans have an estimated cost (and all plan costs are estimates, let's please keep that in mind, even on Actual plans) value of 3 or less. Do you need to adjust the cost threshold in this case? Probably not. But the key is, how do you look at the costs for your plans? Unfortunately, there isn't a property in a DMV that shows this value. Instead,…
Read More
13Feb 2017 by Grant Fritchey 2 Comments

Export All Plans From Cache to a .SQLPLAN File

PowerShell
I was asked if there was an easy way to export all the plans from cache to a .SQLPLAN file. My immediate answer was, "I'm sure there's a PowerShell script out there somewhere." However, rather than do a Gingle search, I figured I'd quickly knock up an example. The Script I've gone minimal on the script. I'm creating a connection to the local instance, defining a command, and returning the data into a data set. From there, since the data set consists of a single column, I'm walking through them all to export out to a file: $Query = 'SELECT deqp.query_plan FROM sys.dm_exec_query_stats AS deqs CROSS APPLY sys.dm_exec_query_plan(deqs.plan_handle) AS deqp WHERE deqp.query_plan IS NOT NULL;' $SqlConnection = New-Object System.Data.SqlClient.SqlConnection $SqlConnection.ConnectionString = 'Server=ServerX\DOJO;Database=master;trusted_connection=true' $PlanQuery = new-object System.Data.SqlClient.SqlCommand $PlanQuery.CommandText = $Query $PlanQuery.Connection…
Read More
07Feb 2017 by Grant Fritchey 4 Comments

Does Query Store Pre-Allocate Space

SQL Server 2016, T-SQL
I love the questions I get while I'm presenting because they force me to think and learn. The question in the title is one I received recently. The answer, now that I'm not standing in front of people, is easy. Of course the space is not pre-allocated. Query Store tables are just system tables. They have a limit on how big they can grow (100mb by default), but that space isn't going to be pre-allocated in any way. The space will just get used as and when it's needed, just like any other system table. However, don't take my word for it, let's prove that. The Test Testing whether or not enabling Query Store is straight forward. Here's a query that should give us information rather quickly: CREATE DATABASE QSTest; GO USE…
Read More
06Feb 2017 by Grant Fritchey No Comments

Still Grateful to Rodney Landrum

Professional Development
So, my blog got hacked. They edited the page where I thanked Rodney for all that he did. I had to remove that post as a part of the cleanup (still ongoing). However, I couldn't let that stand. I've used caching on the internet to track down the original post because that must live on. Here you go Rodney. Thanks again. I recently was honored to take part in the SQL Sons of Beaches Tour. It was a whirlwind of five user groups across the entire state of Florida in five days. I was joined on the tour by Denny Cherry. He and I did most of the presentations (except Tampa where we also had Buck Woody). We were driven from place to place by Karla & Rodney Landrum. I…
Read More
23Jan 2017 by Grant Fritchey 4 Comments

Data About Execution Plans

SQL Server, SQL Server 2016
If you look at the Properties for the first operator of a graphical execution plan, you get all sorts of great information. I've talked about the data available there and how important it is in this older post. Checking out the properties of a plan you're working on is a fundamental part of tuning that plan. What happens when you don't know which plan you should be working on? What do you do, for example, if you want to see all the plans that are currently using ARITHABORT=FALSE or some other plan affecting setting? The "easy" answer to this question is to run an XQuery against the XML of the query plan itself. You can identify these properties and retrieve the appropriate values from within the plan. However, XQuery consumes quite a…
Read More