Voice of the DBA

Author: way0utwest

  • Mission Critical Deployments

    Talk about a lot of pressure to get a software deployment correct. A software install on an Airbus airplane resulted in a file containing parameters being wiped. This error caused (apparently) an airplane to crash when three engines cut off in flight and four people were killed.

    I don’t know if this is the final report on this, but the fact this is a possibility concerns me as a technologist. Certainly we have probably had similar mechanical failures and installation issues in the past, but there are some scary issues here with regards to software. There was a faulty software installation (yikes!), a poor architecture (not assuming more then 2 engines would stop), too much tolerance for software errors (the review letting this pass), and poor overall design (no alerts on the ground).

    I can’t decide if I think that software makes issues like this more or less likely. Certainly checks of physical systems are skipped regularly by people. It’s far easier, and more reliable, to automate checks of software systems, especially with deployments, than it might be for complex mechanical changes. However, maybe that’s not true. Perhaps mechanics are more likely to notice a loose bolt than a misconfigured software menu. Or maybe we need a new type of mechanic that’s savvy with technology.

    Ultimately I think that any software that makes changes to systems, including through deployments, needs to have double checks by an independent process and clear alerting of any issue, not relying on someone to look for the success of a long series of steps. We also need to take review of potential software errors very seriously and ensure the tolerance for potential issues shrinks as the impact of those issues rises.

    Steve Jones

    The Voice of the DBA Podcast

    Listen to the MP3 Audio ( 2.2MB) podcast or subscribe to the feed at iTunes and LibSyn. feed

  • How many environments?

    One of the things I’ve learned over time is that in order to develop software, you need multiple environments. I think that outside of school projects, I’ve always used at least two environments: development and production. At school there were times I worked on software that I also used, and would make changes on my live (and only) system. I had no shortage of regrets, and whenever I question using a Version Control System (VCS) or separate environments, I think back to those days.

    People I meet these days that develop software almost always have more than one environment, and most have at least 3. The most common model might be development, test, and production, but plenty of people work with even more. Maybe not as many as the seven Grant once had to deal with, but I have worked in environments where we had six database environments for one of our software pipelines.

    How many different environments do you work with?

    The poll this week asks for the count in your organization. I realize that you probably have multiple applications and test environments, but choose one or more and give us some answers.

    The most I’ve worked with was in a financial services company. We had a development database and a separate QA system for testing. There was a staging system to mimic production, a Beta database for users to actually test against and production. That worked well, and we were able to easily refresh environments as needed without impacting our development efforts. Mostly because we have a strong DevOps type process.

    Let us know this week how you’ve got your systems set up and what each one is used for in your software pipeline.

    Steve Jones

    The Voice of the DBA Podcast

    Listen to the MP3 Audio ( 2.8MB) podcast or subscribe to the feed at iTunes and LibSyn.

  • Catch up with T-SQL Tuesday

    T-SQL Tuesday is a monthly blog party where we get an invitation the first week of the month to write on a specific topic for the second Tuesday of that month. Adam Machanic came up with the idea and he chooses the hosts.

    If you’re interested in hosting, contact him.

    While there’s a sense of community and participation here, and certainly the chance to showcase some of your knowledge for others, it’s also got another benefit.

    It’s the chance for you to learn something.

    Not by reading other’s posts, but by writing your own. This is your opportunity to bolster your own skills, and teach yourself something new.

    Don’t Worry About Timing

    I know many of you are worried about the pressure of producing something good. I know many of you will find that the first weekend of the month is really busy and you can’t write.

    That’s fine.

    I’ve got a list of all previous invitations and topics. Go back and pick one of them and write your own post today. Start working on it, teach yourself something, and put some thoughts down. Research what others have done by looking through the roundups. Get a friend to review the work and see if it’s readable and makes sense.

    Do that ten times. It might take you ten months, but I’m sure you can write something down about SQL Server once a month.

    When you get ten, start a blog and publish them. Use the T-SQL Tuesday tag, but I’d also encourage you to use the #SQLNewBlogger tag as well. Start showing your boss that you’re improving your skills. Be ready to impress you potential next new boss with a series of posts on SQL topics.

    Your career will be better off, and the world will start to see better software being written.

    Start improving your skills this weekend, or start documenting the learning you already do. Either way, start building a better brand for your career.

  • The Tally Table

    I saw a someone post a question recently about solving a T-SQL problem. One of the answers given used a tally table, which the original poster didn’t understand. A few follow up links pointed them in the right direction, but it got me wondering.

    How many of you know what a tally table is and how to create one? I bet a few of you don’t, which might mean you’ve never had the need. Or it might be a hole in your skill set and you didn’t realize that a tally table can be very useful in solving a number of problems. Anything from generating dates to splitting strings. There are plenty more ways to use one, and feel free to mention more in the comments that others might not have tried.

    I’m not sure the tally table is a core T-SQL skill, but I think it’s an important one you should learn as you grow your skills. After you’ve mastered the basics (Insert/update/delete, aggregates, outer joins) Adding in an understanding of window functions, the APPLY operator, and CTEs are also important to allow you to become better at solving the problems you run into with more efficient T-SQL.

    Steve Jones

    The Voice of the DBA Podcast

    Listen to the MP3 Audio ( 1.7MB) podcast or subscribe to the feed at iTunes and LibSyn. feed