Database Fundamentals #3: What’s In a Database?

Database Fundamentals
It’s worth noting that a lot of people will never need to create their own database. You may never create your own tables or other data structures either. You may only ever run backups and restores and manipulate the security on the system and let application installs create databases for you. That’s completely understandable and perfectly in line with the needs of many businesses and many accidental DBAs. However, it's a good idea to understand what this stuff is and how it works as part of understanding SQL Server. A Database Is Actually Files You need to store information that you want to be able to retrieve later. It’s necessary that you organize that information. If you were working with a word processing program, you store different documents in different…
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The Three T’s of Backups

TSQL
I just read several more horror stories that include, among other things, failed backups. I've said it before (at volume, extreme volume), and evidently I have to say it again. Simply creating a backup file is not enough to ensure the protection of your information. In order to attempt to reinforce the importance of this idea, I'm going to introduce a new concept. Maybe it'll help. I'm calling it "The Three T's of Backups." Take 'Em First, and most important, you have to Take backups. That's your first "T". No, disk redundancy through RAID or a SAN or some other setup is not adequate to protect your information. You must take backups. They have to be created and they have to be run regularly. You absolutely should automate this. Test…
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Database Fundamentals #2: SQL Server Management Studio

Database Fundamentals
The best way to learn any software is to start using it. There are a bunch of software tools in the SQL Server toolbox, but the biggest and most important is SQL Server Management Studio (SSMS). SSMS is where you'll spend most of your time when you start to work with SQL Server. It provides a very large series of graphical user interfaces for creating databases, setting up security, reading data out of the database, and all sorts of other things within your SQL Server instances, the databases stored there, and all the stuff inside those databases. It also supplies you with an interface to the basic scripting language of SQL Server, through which you can do almost anything to the server. The scripting language is called Transact Structured Query…
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T-SQL Tuesday #091 – Databases and DevOps

DevOps
Implementing DevOps with databases presents a unique set of challenges. However, just because something might be hard doesn't mean that it shouldn't be done. I had the opportunity to work with a team of developers, database developers and DBAs under a management team that all agreed on the common goal we had, delivering more, better performing applications, faster. We didn't know it at the time, but we were doing DevOps. DevOps gets a bad name because, well, the problems that DevOps sets out to solve, poor communication, bad teamwork, dysfunctional development and badly configured and maintained processes, are  done by the same team that attempts to implement DevOps. However, they look on it as a purely mechanical switch that they throw, assign some poor person to the role of DevOps…
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Database Fundamentals #1: Install SQL Server

Database Fundamentals
To get started with SQL Server, you need to install it. However, I'm not going to teach you how to do a SQL Server install. Instead, I want to point you towards a couple of sources of information, and, give you some alternatives to installing SQL Server. Install SQL Server As much as I enjoy sharing information with you through this blog, and despite the fact that I read a lot of other technology blogs and other resources online, the single best source of information on SQL Server remains Microsoft and their SQL Server Documentation. This information is up to date and very well maintained. Yes, I'm sure you can find somethings to complain about in there, but overall, it's the starting point for all SQL Server learning and understanding.…
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Query Hash Values, Plan Guides and the Query Store

SQL Server 2016
I was eating dinner with Hugo Kornelis and we started talking about query hash values. You know, like everyone does at dinner. As we talked about it, I suddenly thought about both Plan Guides and the Query Store. I wondered what happened to the query hash values in that case? Thus are blog posts born. Query Hash and Plan Guides The behavior of the query hash itself is fairly straight forward. The text of the query is run through a hashing algorithm within SQL Server and a value comes out, so these two queries: SELECT * FROM Sales.SalesOrderDetail AS sod JOIN Sales.SalesOrderHeader AS soh ON sod.SalesOrderID = soh.SalesOrderID; SELECT * FROM Sales.SalesOrderDetail AS sod JOIN Sales.SalesOrderHeader AS soh ON sod.SalesOrderID = soh.SalesOrderID OPTION (FORCE ORDER); Result in two different query…
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The Age of Data and Software Development

Professional Development
I am so excited to be a data professional in the modern era. Yeah, 15-20 years ago, it was cool to be a DBA and a database developer. However, now, it's amazing. Data drives, or should drive, all our decisions. Whether we're deciding how high to set the cost threshold for parallelism, which query we want to tune, or even which product would serve us best, we should be making these decisions based on data. It's not just about getting the average or the min & max, although, those are the start points. Now, you need to start to take into account standard deviation and you probably should learn how to run a regression analysis. All these tools will make you a better more valuable employee. It's not any different…
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Why You Should Change the Cost Threshold for Parallelism

SQL Server 2005, SQL Server 2008, SQL Server 2012, SQL Server 2014, SQL Server 2016
I've written several times about the Cost Threshold for Parallelism and it's relationship to your execution plans, how to determine your execution plan cost, and even how to decide what value to set your Cost Threshold to. What I haven't explicitly addressed in extremely clear terms is why you should adjust your Cost Threshold for Parallelism. There are two reasons to modify this value. Cost Threshold for Parallelism Default Value The primary reason to change the Cost Threshold for Parallelism is because the default value is not a good choice for the vast majority of systems. The default value is 5. This means that when a query has an estimated cost greater than 5, it may get a parallel execution plan. Microsoft set the default value for the Cost Threshold…
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Determining the Cost Threshold for Parallelism

SQL Server 2005, SQL Server 2008, SQL Server 2012, SQL Server 2014, 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 <-…
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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…
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