Voice of the DBA

Author: way0utwest

  • No @@ServerName on Linux

    I setup a new instance of SQL Server on Linux some time ago. At the time, the Linux machine didn’t have any Samba running, and no real “name” on the network. As a result, after installing SQL Server I got a NULL when running SELECT @@SERVERNAME.

    The fix is easy. It’s what you’d do if you had the wrong name. You run:

    sp_addserver ‘Ubuntu’, Local

    In this case, Ubuntu was the name I gave my machine under the Samba server, since that’s the OS. I don’t plan on adding more for now, so this is fine.

    After the chance, I couldn’t restart the instance from SSMS, so on the host itself, I ran a

    sudo systemctl stop mssql-server
sudo systemctl start mssql-server

    That completed, and my @@servername is now working.

  • Get What You Pay For?

    Many items that we choose to buy have some relation between the price and the quality of the item. We often find that a more expensive appliance or automobile has better quality than a cheaper one. There’s certainly a point at which spending more doesn’t necessarily get you better quality or even value. This seems especially true today with many “over the top” products that have added features or design that don’t seem to be worth the additional cost. At the other end, there are times many of us pay less for less quality, consciously making that tradeoff. I also think that the base level of quality has risen for so many products that it might not be worth spending more than some amount for an item. They’re all close in value and performance.

    I ran across a piece that looks at the value of consumer and enterprise SSDs. This isn’t a scientific analysis, but rather a short discussion of why enterprise SSDs might be more than twice as expensive as consumer ones. There are some details, such as the architecture and spare capacity, but ultimately the author notes that people purchasing drives also worry about the perception that they might have saved money with a cheaper drive, but lost data because the warranty and support are lower. Even if the same hardware were being sold by the vendor, which I’m sure happens, having enterprise support is a crutch that can provide the employee some protection if there are issues.

    There certainly are hardware differences for most devices, though the buyer should beware and verify that they are actually buying enterprise level gear. The big difference for me is that the large over provisioning of enterprise devices offers more predictable performance sustained over longer periods of time. This is important, especially for databases that might get quite a bit of transaction log or tempdb activity. In those cases, we need sustained high rates of I/O.

    There are no shortage of white papers, articles, reviews, and vendor claims about their particular hardware. This is a very competitive and also highly profitably space. If you’ve had to purchase a new SAN device at any point, you know these are expensive and complex. Making the decision is stressful as it can take lots of time ot evalute, lots of resources to get things installed, and so it’s not easy to go back on the purchase. In addition, many of us that have to make a recommendation are usually asking management to spend 6 or 7 figures on a device. If it doesn’t perform, we will take the blame and may find our choice to be career limiting.

    I don’t envy anyone that needs to make hardware decisions for their database or organization. There are so many companies in the storage space now that it’s a large project just to evaluate the various products and try to make a decision. It’s complex enough these days that I can see why moving to the cloud is attractive for some. While we can’t control everything and we may have large monthly bills, we typically don’t ever have to face that extremely large capital purchase decision.

    Steve Jones

    The Voice of the DBA Podcast

    Listen to the MP3 Audio ( 4.5MB) podcast or subscribe to the feed at iTunes and Libsyn.

  • The June 2018 SQL in the City is coming

    We’ve got the schedule up and you can register today. Once again I’m heading to the UK, along with Grant, to broadcast a series of sessions that we hope will help you learn a bit more about building better database software and protecting data.  Kathi’s recording her session as she’ll be in Hawaii that week (she declined to trade with me).

    The theme this time is Compliant Database DevOps. Lots of people are struggling and coming to terms with the GDPR changes. I’d argue, as would others, that really most of the world ought to have better data handling, so we’ll give you some thoughts and ideas here of how to do this. We’ll use some Redgate products, but we’re hoping you get the overall concepts and ideas as well.

    Join me on June 20 and get a one day conference from the comfort of your own office.

  • SQL Server Tuning Skills

    Performance tuning a SQL Server instance, database, or even query is a skill that most of us could improve. In fact, I see that the query performance presentations are often the most popular learning items at any event. I’ve seen quite a few people asking for more tuning talks in different areas, which is a good thing. I think most SQL Saturdays could schedule a different tuning session every hour, or even repeat the same one a few times, and the room would be mostly full each time.

    Learning to look at the various possible problems in a SQL Server is both a science and an art. There are good methods, such as waits and queues, for examining where an issue occurs. There are basic techniques for looking at execution plans and then making changes to indexes or T-SQL. There are different options for queries, SET values, and more that will affect your query or even all your queries.

    Sometimes it seems there might be too many options for a beginner to decide how to begin examining a system, especially one that is having issues. I can’t cover all of the issues in this short piece, but I can give you some guidance that might help. First, make sure that you know how to gather information about your issue. We have forums at SQLServerCentral to answer your questions, but you have to do some work. Gail Shaw wrote a great piece on how to post performance problems.

    Ultimately, you need to understand the recommendations that we may give. It’s helpful to learn about indexes, and the differences in the various types (including Columnstore). You should also have a baseline so that you can measure the impact of your changes. How do you know the problem is fixed? Maybe the user gets lucky with a quicker experience when you tell them you’ve changed the system, but will they call again soon? That second call might be worse than the first one. Even getting a baseline of the poor performance now will help you understand (and prove) that the system is running better.

    You also need to understand what not to tune, and which items to ignore. I thought quite a bit about this after reading Paul Randal’s post on wait types to ignore. This is part of his 101 series, which are a good way to start improving your skills. Performance tuning takes practice and knowledge, which takes time to acquire. Even if you’re fighting a problem today, try and learn a little something about how you get your system to run better.

    I’d also recommend that you look to continue your education over time. Take advantage of those sessions at local events, like user groups, virtual groups, and SQL Saturdays. Take advantage of pre-cons at larger events, which pack lots of learning into a few hours. If you go, take a paper pad, not a laptop, and take lots of notes. If you can’t get away, maybe you can lobby for some tuning classes from sqlSkills, Brent Ozar Unlimited, or even self-paced courses on Pluralsight.

    Learning to become better at tuning is an ongoing process, and one that requires some investment. Perhaps some money, but definitely some time and practice are necessary. Don’t let this be a daunting task, but one that’s a journey. Your goal is to get a little better each time you work on this skill, not to be an expert that knows it all. I’m not sure anyone gets to that point, but you can become as good at this skill as any of the presenters you watch. It might take you longer than it took them, but you’re also able to build on their work and learn from their knowledge. Take advantage of that opportunity.

    Steve Jones