Every server, database, storage appliance and network encounter some sort of performance issues. It is a major part of our job as database administrators to properly monitor and fix those performance issues whether it is in your traditional on premises environment or in the cloud. This article will cover ways monitoring performance and how to establish a baseline. We will go over several important performance metrics every database administrator should know and how to gather and interpret those metrics through several different options within SQL Server and your Windows operating system. Now which tool you use to accumulate these metrics depends on what problem you are trying to solve. The…
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“One Gerbil, Two Gerbils or Three Gerbils?” is a common DBA joke about server and storage performance. No matter how many gerbils power your storage, you need to know what type they are and the power that they provide. Storage is not about gerbils it is about IOPs, bandwidth, latency, and tiers. As a DBA it is important for you to understand and know what kind of storage is attached to your servers and how it is handling your data. It is not important to master everything about it, but it is very advantageous to be able to talk to your storage admins or “Gerbil CoLo, LLC” provider intelligently especially…
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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 that file can get tricky so I created this flow…
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Does your server look like this? Many of us have inherited a SQL Server instance that has all SQL Services installed. Someone, maybe even you, went through the SQL Server installation process using GUI and checked every option available to them, then just clicked Next, Next, Next and then Install. If this is your environment, please take a moment to evaluate and decide which of these services that are required. From a performance tuning perspective, it is important to only run the services that you need. Each of these services can consume resources on your server. Sharing resources reduces what youe SQL Server Engine, SQL Server (MSSQLSERVER) or named instance…
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It is widely known that I am a horrible speller and hate to type code. I tend to use a lot of code snippets and reuse code to avoid writing it. So, when I find little tips that make coding easier for me, I like to share. Did you know that you can surround your code with a click of a button with IF, BEGIN END, WHILE code blocks? SQL Server Management Studio (SSMS) gives us the basic structure of a Transact-SQL statement code block as a starting point. Take Look In SSMS In a query window, Right Click and Choose Surround With (note the hot keys of Ctrl+K or…
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When you run a query twice, and get dramatically different run times, your first step can be to try to identify the differences in execution plans. For many that means running the two different queries (before & after) and splitting you screen in order to visually compare the plans. Did you know SQL Server Management Studio gives you the option to compare to different execution plans? It makes it easy not only to visualize the differences, but it also shows you detail properties that allow you to dive into the numbers. This functionality was introduced with SQL Server 2016, and is also part of the functionality of the Query Store…
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In this post, we continue with another beginner’s blog of database features that may be unknown to many. Let’s take a look at filtered indexes. Many database administrators are fully aware of the power of indexes and know how to create them. However, I find that some have yet to dive into fully optimizing their indexes and taking advantage of what filtered indexes has to offer. What is a filtered index? Simply it’s an index with a where clause. It is an optimized non clustered index that can be narrowed down in scope to better fit a subset of data. Example being date ranges, years, non NULLs or specific product…
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I give performance presentations at many different events to all levels of SQL Server professionals. Over time I’ve noticed that some DBAs and developers have never looked at the dynamic management views (dmv’s) that are available within SQL Server starting with SQL Server 2005. These DMVs are useful means to determine what is going on with a particular SQL Server instance. So, in this post I am going to list a few of my very favorite DMVs as a reference for those who may be new to them. Performance Tuning These dynamic management views are what I use first when looking to any performance issues or I need to know…
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Another quick post of simple changes you can make to your code to create more optimal execution plans. This one is on implicit conversions. An implicit conversion is when SQL Server must automatically convert a data type from one type to another when comparing values, moving data or combining values with other values. When these values are converted, during the query process, it adds additional overhead and impacts performance. Here is a great chart by Microsoft that shows you conversions and which will cause an implicit or explicit conversion. In this post I will not go into explicit, just know that is what you explicitly tell SQL Server to CAST…
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One of the easiest things to fix when performance tuning queries are Key Lookups or RID Lookups. The key lookup operator occurs when the query optimizer performs an index seek against a specific table and that index does not have all of the columns needed to fulfill the result set. SQL Server is forced to go back to the clustered index using the Primary Key and retrieve the remaining columns it needs to satisfy the request. A RID lookup is the same operation but is performed on a table with no clustered index, otherwise known as a heap. It uses a row id instead of a primary key to do…
