Tag: SQL Server

Mastering TempDB: The Basics

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I regularly deliver a presentation called “Mastering TempDB”. I wrote it based on what I wish I knew about TempDB “growing up” in my career as a SQL Server DBA. It really is a breakdown of what TempDB is, how it is used, what problems actually occur within it, and how to best configure it. With advice from my colleagues, I have decided to break that down into this article to educate you. What is TempDB? TempDB is a global resource used by everyone and everything inside SQL Server. Think of it as a dumping ground for anything that doesn’t… Continue Reading

Resizing Tempdb (When TEMPDB Wont Shrink)

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Occasionally, we must resize or realign our Tempdb log file (.ldf) or data files (.mdf or .ndf) due to a growth event that forces the file size out of whack. To resize we have three options, restart the SQL Server Service, add additional files, or shrink the current file. We most likely have all been faced with run away log files and in an emergency situation restarting the SQL Services may not be an option but we still need to get our log file size smaller before we run out of disk space for example. The process of shrinking down… Continue Reading

Adaptive Joins in SQL Server

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SQL Server 2017 (compatibility 140) brought us many Intelligent Query Processing (IQP), formally known as Adaptive Query Processing, features that improve performance on workloads straight out of the box with no code changes to implement. One of those features introduced was Adaptive Joins. In this feature the join operator is dynamically determined at runtime by the optimizer, which defines a threshold number of rows and then chooses between a Nested Loop or Hash Match join operator. This operator switch can produce a better join and improve performance of your queries without you having to lift a finger. Not all queries… Continue Reading

Change Azure SQL Database Service Level Objectives in SSMS

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Sometimes as a DBA, I am lazy and want the ability to execute all of my tasks in one place. Lucky for me I discovered the other day that I can change my Azure SQL Database Service Level Object options within SQL Server Management Studio (SSMS) without ever having to go to the Azure Portal. By right clicking on your database properties and choosing the Configure SQL page you can change your Subscription and Azure Location. Even more and what is really cool is I can also scale up and down my Edition (which is generally referred to as Service… Continue Reading

Caution When Dropping Unused Indexes on an Azure SQL Database

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Index Maintenance is an important aspect of database health. Above and beyond regular index rebuilds and reorganizations it is important to understand the usage of the indexes on your database. Cleaning up unused indexes can save a lot of overhead on Insert/Update/Delete operations. To achieve that goal, I typically run a script like the one shown below and check out whether or not an index has had any seeks or scans against it as a starting point in my cleanup regiment. SELECT d.name,        OBJECT_NAME(i.[object_id]) AS [ObjectName],        i.[name] AS [IndexName],        s.user_seeks,        s.user_scans FROM sys.indexes AS i    … Continue Reading

What is Azure SQL Database Serverless?

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What is Azure SQL Database Serverless? When I hear the term serverless my mind gets confused. How can a database exist without a server? Azure is a cloud platform, is my database just floating in the air? No, I am not really thinking that, but still the word serverless can be hard to understand. So, let’s walk through what it is. Serverless is a term commonly used for function as a service patterns like Amazon Lambda, or Azure Functions, where you have a piece of code that is called and executed without you deploying any infrastructure. Azure Logic Apps are… Continue Reading

What is Batch Mode on Rowstore in SQL Server?

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Under compatibility level 150, in both SQL Server 2019 and Azure SQL Database, you now can use batch mode for CPU-bound analytic type workloads without requiring columnstore indexes. There is no action needed to turn on batch mode aside from being on the proper compatibility mode. You also have the ability to enable it as a database scoped configuration option (as shown below), and you can hint individual queries to either use or not use batch mode (also shown below). If you recall in my earlier blogs on columnstore, it is batch mode in conjunction with page compression that drastically… Continue Reading

Coding Standards Gone Bad in SQL Server

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Knowing your data is very important when it comes to writing code. Now I’ll admit that I am very far from being a developer, however as a DBA, I spend much of my day’s performance tuning code. In doing so, I get to see many ways code can introduce excess database reads. One of the most recent things I have come across has to do with NULLs. The environment I was working in had no default values in their table design, so it was riddled with NULL values. Over the years they had implemented coding standards to try and mitigate… Continue Reading

Moving Your SQL Workload to the Cloud   

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Every day, more IT organizations decide to move their SQL Server databases to Azure. In fact, over a million on-premises SQL Server databases have been moved to Azure. There’s an interesting blog about how Microsoft is faster and cheaper than its competitors that’s worth a read. To assist with your move to Azure Microsoft offers a number of migration tools and services to make this move as smooth as possible which I think attributes to their success. Two of those options are below with some informational links. If you’re migrating a number of large SQL Server instances, Azure Database Migration… Continue Reading

String Split Function in SQL Server

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Did you know that a native STRING_SPLIT function built into SQL Server was added into SQL Server 2016? As a consultant I see so much code that call out to a scalar function that are used to split out string delimited variables into a usable list. For those that use this method I suggest you look at this function. STRING_SPLIT is a table valued function that returns a single column of your string values split out by the delimiter. This is an unusual bit of T-SQL, in that compatibility level 130 or higher is required for its use (Microsoft didn’t… Continue Reading