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• Linux distro for software development support?

  - by Xie Jilei

  I've spent too much time on setup & maintain a development server, which contains following tools: Common services like SSH, BIND, rsync, etc. Subversion, Git. Apache server, which runs CGit, Trac, Webmin, phpmyadmin, phppgadmin, etc. Jetty, which runs Archiva and Hudson. Bugzilla. PostgresSQL server, MySQL server. I've created a lot of Debian packages, like my-trac-utils, my-bugzilla-utils, my-bind9-utils, my-mysql-utils, etc. to make my life more convenient. However, I still feel I need a lot more utils. And I've spent a lot of time to maintain these packages, too. I think there maybe many developers doing the same things. As tools like subversion, git, trac are so common today. It's not to hard to install and configure each of them, but it took a long time to install them all. And it's time consuming to maintain them. Like backup the data, plot the usage graph and generate web reports. (gitstat for example) So, I'd like to hear if there exist any pre-configured distro for Development Server purpose, i.e., something like BackTrack for hackers?

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• Distributing entropy to virtual machines.

  - by Louis

  Dear All, I'm interested in generating secret keys for SSL on virtual machines using true randomness. By true randomness I mean the same level of entropy that can be generated by UNIX's dev/random and entropy gathering daemon (EGD). Is there a "general knowledge" recipe to route entropy from the physical layer to the virtual machines via the hypervisor regardless of the Hypervisor/Guest OS combination? Example: suppose one "hypervises" with VMware VSphere and instantiates Windows Guest OS. Can this hypervisor collect entropy from its peripherals (like dev/random/ would) and distribute it to these guest Windows OS? When considering the big vendors (VMware, Hyper-V, Citrix, etc), do they have entropy pools that gather entropy that can easily be pushed to their respective virtual machines? Louis

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• "Agile Principles, Patterns, and Practices in C#": Is this just a .NET-translation of the popular Uncle Bob book?

  - by Louis Rhys

  I found this book sold on Amazon Agile Principles, Patterns, and Practices in C#, written by Robert C Martin and Micah Martin. Is it merely a .NET port of the older, more popular Agile Software Development, Principles, Patterns, and Practices? Or is it just a new book trying to take advantage of the other book's popularity? If I am a .NET developer who hasn't read either book, which one would you recommend?

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• Bingbot seems to be adding "ForceRecrawl: 0" to URLs when crawling my sites

  - by Louis Somers

  I'm seeing this in the iis-logs of two websites that I maintain: GET /an/existing/page/on/my/site+ForceRecrawl:+0 - 80 - 207.46.195.105 HTTP/1.1 Mozilla/5.0+(compatible;+bingbot/2.0;++http://www.bing.com/bingbot.htm) I get about one or two of these per day from these IP addresses: 207.46.195.105, 65.52.110.190.. an more, all belonging to msnbot-ip.search.msn.com Probably Microsoft has a bug in their crawler? Any way, doing a search on "ForceRecrawl: 0" in major search engines comes up with a bunch of random sites. Doing the search on StackOverflow or here gave no results (to my amazement). Am I the only one seeing this? I first noticed these on the 9th of this month, and I'm seeing them pass almost daily since... Another thing that I think is crazy, is that the URL http://www.bing.com/bingbot.htm redirects to mail.live.com (hotmail). Currently I'm returning 404's but I'm considering to catch these, strip the trailing " ForceRecrawl: 0" and process as if it were a legitimate url. Could anyone shed some light on this? Could it have to do with some configuration or so in Bing's Webmaster Tools?

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• What Counts For a DBA: Simplicity

  - by Louis Davidson

  Too many computer processes do an apparently simple task in a bizarrely complex way. They remind me of this strip by one of my favorite artists: Rube Goldberg. In order to keep the boss from knowing one was late, a process is devised whereby the cuckoo clock kisses a live cuckoo bird, who then pulls a string, which triggers a hat flinging, which in turn lands on a rod that removes a typewriter cover…and so on. We rely on creating automated processes to keep on top of tasks. DBAs have a lot of tasks to perform: backups, performance tuning, data movement, system monitoring, and of course, avoiding being noticed.  Every day, there are many steps to perform to maintain the database infrastructure, including: checking physical structures, re-indexing tables where needed, backing up the databases, checking those backups, running the ETL, and preparing the daily reports and yes, all of these processes have to complete before you can call it a day, and probably before many others have started that same day. Some of these tasks are just naturally complicated on their own. Other tasks become complicated because the database architecture is excessively rigid, and we often discover during “production testing” that certain processes need to be changed because the written requirements barely resembled the actual customer requirements.   Then, with no time to change that rigid structure, we are forced to heap layer upon layer of code onto the problematic processes. Instead of a slight table change and a new index, we end up with 4 new ETL processes, 20 temp tables, 30 extra queries, and 1000 lines of SQL code.  Report writers then need to build reports and make magical numbers appear from those toxic data structures that are overly complex and probably filled with inconsistent data. What starts out as a collection of fairly simple tasks turns into a Goldbergian nightmare of daily processes that are likely to cause your dinner to be interrupted by the smartphone doing the vibration dance that signifies trouble at the mill. So what to do? Well, if it is at all possible, simplify the problem by either going into the code and refactoring the complex code to simple, or taking all of the processes and simplifying them into small, independent, easily-tested steps.  The former approach usually requires an agreement on changing underlying structures that requires countless mind-numbing meetings; while the latter can generally be done to any complex process without the same frustration or anger, though it will still leave you with lots of steps to complete, the ability to test each step independently will definitely increase the quality of the overall process (and with each step reporting status back, finding an actual problem within the process will be definitely less unpleasant.) We all know the principle behind simplifying a sequence of processes because we learned it in math classes in our early years of attending school, starting with elementary school. In my 4 years (ok, 9 years) of undergraduate work, I remember pretty much one thing from my many math classes that I apply daily to my career as a data architect, data programmer, and as an occasional indentured DBA: “show your work”. This process of showing your work was my first lesson in simplification. Each step in the process was in fact, far simpler than the entire process.  When you were working an equation that took both sides of 4 sheets of paper, showing your work was important because the teacher could see every step, judge it, and mark it accordingly.  So often I would make an error in the first few lines of a problem which meant that the rest of the work was actually moving me closer to a very wrong answer, no matter how correct the math was in the subsequent steps. Yet, when I got my grade back, I would sometimes be pleasantly surprised. I passed, yet missed every problem on the test. But why? While I got the fact that 1+1=2 wrong in every problem, the teacher could see that I was using the right process. In a computer process, the process is very similar. We take complex processes, show our work by storing intermediate values, and test each step independently. When a process has 100 steps, each step becomes a simple step that is tested and verified, such that there will be 100 places where data is stored, validated, and can be checked off as complete. If you get step 1 of 100 wrong, you can fix it and be confident (that if you did your job of testing the other steps better than the one you had to repair,) that the rest of the process works. If you have 100 steps, and store the state of the process exactly once, the resulting testable chunk of code will be far more complex and finding the error will require checking all 100 steps as one, and usually it would be easier to find a specific needle in a stack of similarly shaped needles.  The goal is to strive for simplicity either in the solution, or at least by simplifying every process down to as many, independent, testable, simple tasks as possible.  For the tasks that really can’t be done completely independently, minimally take those tasks and break them down into simpler steps that can be tested independently.  Like working out division problems longhand, have each step of the larger problem verified and tested.

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• What Counts For a DBA: Ego

  - by Louis Davidson

  Leaving aside, for a second, Freud’s psychoanalytical definitions, the term “ego” generally refers to a person’s sense of self, and their self-esteem. In casual usage, however, it usually appears in the adjectival form, “egotistical” (most often followed by “jerk”). You don’t need to be a jerk to be a DBA; humility is important. However, ego is important too. A good DBA needs a certain degree of self-esteem…a belief and pride in what he or she can do better than anyone else can. The ideal DBA needs to be humble enough to admit when they are wrong but egotistical enough to know when they are right, and to stand up for that knowledge and make their voice heard. In most organizations, the DBA team is seriously outnumbered by headstrong developers and clock driven managers, and “great” DBAs will often be outnumbered by…well…the not so great. In order to be heard in this environment, a DBA will not only need to be very skilled, but will also need a healthy dose of ego. As Freud might have put it, the unconscious desire of the DBA (the id) is for iron-fist control over their databases, and code that runs in them. However, the ego moderates this desire, seeking to “satisfy the id in realistic ways that, in the long term, bring benefit rather than grief“. In other words, the ego understands the need to exert a measure of control and self-belief, but also to tolerate and play nicely with developers and other DBAs. The trick, naturally, is learning how to be heard when it is important, but also to make everyone around you welcome that input, even when you have to be bold to make the “I know what I am talking about, and you…well…not so much” decisions. Consider a baseball team, bottom of the ninth inning of the championship game, man on first and down one run. Almost anyone on that team will have the ability to hit a home run, but only one or two will have the iron belief that they can pull it off in this critical, end-game situation. The player you need in this situation is the one who has passionately gone the extra mile preparing for just this moment, is bursting at the seams with self-confidence, and can look the coach in the eye and state, boldly, “Put me in, I am your best bet“. Likewise, on those occasions when high customer demand coincides with copious system errors, and panic is bubbling just beneath the surface, you don’t need the minimally qualified support person, armed with the “reboot and hope” technique (though that sometimes works!). You need the DBA who steps up and says, “Put me in” and has the skill and tenacity to back up those words and to fix the pinpoint and fix the problem, whatever it takes, while keeping customers and managers happy. Of course, the egotistical DBA will happily spend hours telling you how great they are at their job, and how brilliantly they put out a previous fire, and this is no guarantee that they can deliver. However, if an otherwise-humble DBA looks you in the eye and says, “I can do it”, then hear them out. Sometimes, this burst of ego will be exactly what’s required.

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• How to name an subclass that add a minor, detailed thing?

  - by Louis Rhys

  What is the most concise (yet descriptive) way of naming a subclass that only add a specific minor thing to the parent? I encountered this case a lot in WPF, where sometime I have to add a small functionality to an out-of-the-box control for specific cases. Example: TreeView doesn't change the SelectedItem on right-click, but I have to make one that does in my application. Some possible names are TreeViewThatChangesSelectedItemOnRightClick (way too wordy and maybe difficult to read because there is so many words concantenated together) TreeView_SelectedItemChangesOnRightClick (slightly more readable, but still too wordy and the underscore also breaks the normal convention for class names) TreeViewThatChangesSIOnRC (non-obvious acronym), ExtendedTreeView (more concise, but doesn't describe what it is doing. Besides, I already found a class called this in the library, that I don't want to use/modify in my application). LouisTreeView, MyTreeView, etc. (doesn't describe what it is doing). It seems that I can't find a name which sounds right. What do you do in situation like this?

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• What Counts For a DBA – Decisions

  - by Louis Davidson

  It’s Friday afternoon, and the lead DBA, a very talented guy, is getting ready to head out for two well-earned weeks of vacation, with his family, when this error message pops up in his inbox: Msg 211, Level 23, State 51, Line 1. Possible schema corruption. Run DBCC CHECKCATALOG. His heart sinks. It’s ten…no eight…minutes till it’s time to walk out the door. He glances around at his coworkers, competent to handle many problems, but probably not up to the challenge of fixing possible database corruption. What does he do? After a few agonizing moments of indecision, he clicks shut his laptop. He’ll just wait and see. It was unlikely to come to anything; after all, it did say “possible” schema corruption, not definite. In that moment, his fate was sealed. The start of the solution to the problem (run DBCC CHECKCATALOG) had been right there in the error message. Had he done this, or at least took two of those eight minutes to delegate the task to a coworker, then he wouldn’t have ended up spending two-thirds of an idyllic vacation (for the rest of the family, at least) dealing with a problem that got consistently worse as the weekend progressed until the entire system was down. When I told this story to a friend of mine, an opera fan, he smiled and said it described the basic plotline of almost every opera or ‘Greek Tragedy’ ever written. The particular joy in opera, he told me, isn’t the warbly voiced leading ladies, or the plump middle-aged romantic leads, or even the music. No, what packs the opera houses in Italy is the drama of characters who, by the very nature of their life-experiences and emotional baggage, make all sorts of bad choices when faced with ordinary decisions, and so move inexorably to their fate. The audience is gripped by the spectacle of exotic characters doomed by their inability to see the obvious. I confess, my personal experience with opera is limited to Bugs Bunny in “What’s Opera, Doc?” (Elmer Fudd is a great example of a bad decision maker, if ever one existed), but I was struck by my friend’s analogy. If all the DBA cubicles were a stage, I think we would hear many similarly tragic tales, played out to music: “Error handling? We write our code to never experience errors, so nah…“ “Backups failed today, but it’s okay, we’ll back up tomorrow (we’ll back up tomorrow)“ And similarly, they would leave their audience gasping, not necessarily at the beauty of the music, or poetry of the lyrics, but at the inevitable, grisly fate of the protagonists. If you choose not to use proper error handling, or if you choose to skip a backup because, hey, you haven’t had a server crash in 10 years, then inevitably, in that moment you expected to be enjoying a vacation, or a football game, with your family and friends, you will instead be sitting in front of a computer screen, paying for your poor choices. Tragedies are very much part of IT. Most of a DBA’s day to day work has limited potential to wreak havoc; paperwork, timesheets, random anonymous threats to developers, routine maintenance and whatnot. However, just occasionally, you, as a DBA, will face one of those decisions that really matter, and which has the possibility to greatly affect your future and the future of your user’s data. Make those decisions count, and you’ll avoid the tragic fate of many an operatic hero or villain.

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• What Counts For A DBA: ESP

  - by Louis Davidson

  Now I don’t want to get religious here, and I’m not going to, but what I’m going to describe in this ‘What Counts for a DBA’ installment sometimes feels like magic. Often  I will spend hours thinking about the solution to a design issue or coding problem, working diligently to try to come up with a solution and then finally just give up with the feeling that I’m not even qualified to be a data entry clerk, much less a data architect.  At this point I often take a walk (or sometimes a nap), and then it hits me. I realize that I have the answer just sitting in my brain, ready to implement.  This phenomenon is not limited to walks either; it can happen almost any time after I stop my obsession about a problem. I call this phenomena ESP (or Extra-Sensory Programming.)  Another term for this could be ‘sleeping on it’, and while the idiom tends to mean to let time pass to actively think about a problem, sleeping on a problem also lets you relax and let your brain do the work. I first noticed this back in my college days when I would play video games for hours on end. We would get stuck deep in some dungeon unable to find a way out, playing for days on end until we were beaten down tired. Once we gave up and walked away, the solution would usually be there waiting for one of us before we came back to play the next day.  Sometimes it would be in the form of a dream, and sometimes it would just be that the problem was now easy to solve when we started to play again.  While it worked great for video games, it never occurred when I studied English Literature for hours on end, or even when I worked for the same sort of frustrating hours attempting to solve a homework problem in Calculus.  I believe that the difference was that I was passionate about the video game, and certainly far less so about homework where people used the word “thou” instead of “you” or x to represent a number. This phenomenon occurs somewhat more often in my current work as a professional data programmer, because I am very passionate about SQL and love those aspects of my career choice.  Every day that I get to draw a new data model to solve a customer issue, or write a complex SELECT statement to ferret out the answer to a complex data question, is a great day. I hope it is the same for any reader of this blog.  But, unfortunately, while the day on a whole is great, a heck of a lot of noise is generated in work life. There are the typical project deadlines, along with the requisite project manager sitting on your shoulders shouting slogans to try to make you to go faster: Add in office politics, and the occasional family issues that permeate the mind, and you lose the ability to think deeply about any problem, not to mention occasionally forgetting your own name.  These office realities coupled with a difficult SQL problem staring at you from your widescreen monitor will slowly suck the life force out of your body, making it seem impossible to solve the problem This is when the walk starts; or a nap. Maybe you hide from the madness under your desk like George Costanza hides from Steinbrenner on Seinfeld.  Forget about the problem. Free your mind from the insanity of the problem and your surroundings. Then let your training and education deep in your brain take over and see if it will passively do the rest for you. If you don’t end up with a solution, the worst case scenario is that you have a bit of exercise or rest, and you won’t have heard the phrase “better is the enemy of good enough” even once…which certainly will do your brain some good. Once you stop expecting whipping your brain for information, inspiration may just strike and instead of a humdrum solution you find a solution you hadn’t even considered, almost magically. So, my beloved manager, next time you have an urgent deadline and you come across me taking a nap, creep away quietly because I’m working, doing some extra-sensory programming.

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• What Counts For a DBA: Replaceable

  - by Louis Davidson

  Replaceable is what every employee in every company instinctively strives not to be. Yet, if you’re an irreplaceable DBA, meaning that the company couldn’t find someone else who could do what you do, then you’re not doing a great job. A good DBA is replaceable. I imagine some of you are already reaching for the lighter fluid, about to set the comments section ablaze, but before you destroy a perfectly good Commodore 64, read on… Everyone is replaceable, ultimately. Anyone, anywhere, in any job, could be sitting at their desk reading this, blissfully unaware that this is to be their last day at work. Morbidly, you could be about to take your terminal breath. Ideally, it will be because another company suddenly offered you a truck full of money to take a new job, forcing you to bid a regretful farewell to your current employer (with barely a “so long suckers!” left wafting in the air as you zip out of the office like the Wile E Coyote wearing two pairs of rocket skates). I’ve often wondered what it would be like to be present at the meeting where your former work colleagues discuss your potential replacement. It is perhaps only at this point, as they struggle with the question “What kind of person do we need to replace old Wile?” that you would know your true worth in their eyes. Of course, this presupposes you need replacing. I’ve known one or two people whose absence we adequately compensated with a small rock, to keep their old chair from rolling down a slight incline in the floor. On another occasion, we bought a noise-making machine that frequently attracted attention its way, with unpleasant sounds, but never contributed anything worthwhile. These things never actually happened, of course, but you take my point: don’t confuse replaceable with expendable. Likewise, if the term “trained seal” comes up, someone they can teach to follow basic instructions and push buttons in the right order, then the replacement discussion is going to be over quickly. What, however, if your colleagues decide they’ll need a super-specialist to replace you. That’s a good thing, right? Well, usually, in my experience, no it is not. It often indicates that no one really knows what you do, or how. A typical example is the “senior” DBA who built a system just before 16-bit computing became all the rage and then settled into a long career managing it. Such systems are often central to the company’s operations and the DBA very skilled at what they do, but almost impossible to replace, because the system hasn’t evolved, and runs on processes and routines that others no longer understand or recognize. The only thing you really want to hear, at your replacement discussion, is that they need someone skilled at the fundamentals and adaptable. This means that the person they need understands that their goal is to be an excellent DBA, not a specialist in whatever the-heck the company does. Someone who understands the new versions of SQL Server and can adapt the company’s systems to the way things work today, who uses industry standard methods that any other qualified DBA/programmer can understand. More importantly, this person rarely wants to get “pigeon-holed” and so documents and shares the specialized knowledge and responsibilities with their teammates. Being replaceable doesn’t mean being “dime a dozen”. The company might need four people to take your place due to the depth of your skills, but still, they could find those replacements and those replacements could step right in using techniques that any decent DBA should know. It is a tough question to contemplate, but take some time to think about the sort of person that your colleagues would seek to replace you. If you think they would go looking for a “super-specialist” then consider urgently how you can diversify and share your knowledge, and start documenting all the processes you know as if today were your last day, because who knows, it just might be.

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• String patterns that can be used to filter and group files

  - by Louis Rhys

  One of our application filters files in certain directory, extract some data from it and export a document from the extracted data. The algorithm for extracting the data depends on the file, and so far we use regex to select the algorithm to be used, for example .*\.txt will be processed by algorithm A, foo[0-5]\.xml will be processed by algo B, etc. However now we need some files to be processed together. For example, in one case we need two files, foo.*\.xml and bar.*\.xml. Part of the information to be extracted exist in the foo file, and the other part in the bar file. Moreover, we need to make sure the wild card is compatible. For example, if there are 6 files foo1.xml foo23.xml bar1.xml bar9.xml bar23.xml foo4.xml I would expect foo1 and bar1 to be identified as a group, and foo23 and bar23 as another group. bar9 and foo4 has no pair, so they will not be treated. Now, since the filter is configured by user, we need to have a pattern that can express the above requirement. I don't think you can express meaning like above in standard regex. (foo|bar).*\.xml will match all 6 file above and we can't identify which file is paired for a particular file. Is there any standard pattern that can express it? Or any idea how to modify regex to support this, that can be implemented easily?

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• How to decide whether to implement an operation as Entity operation vs Service operation in Domain Driven Design?

  - by Louis Rhys

  I am reading Evans's Domain Driven Design. The book says that there are entity and there are services. If I were to implement an operation, how to decide whether I should add it as a method on an entity or do it in a service class? e.g. myEntity.DoStuff() or myService.DoStuffOn(myEntity)? Does it depend on whether other entities are involved? If it involves other entities, implement as service operation? But entities can have associations and can traverse it from there too right? Does it depend on stateless or not? But service can also access entities' variable, right? Like in do stuff myService.DoStuffOn, it can have code like if(myEntity.IsX) doSomething(); Which means that it will depend on the state? Or does it depend on complexity? How do you define complex operations?

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• Application layer vs domain layer?

  - by Louis Rhys

  I am reading Domain-Driven Design by Evans and I am at the part discussing the layered architecture. I just realized that application and domain layers are different and should be separate. In the project I am working on, they are kind of blended and I can't tell the difference until I read the book (and I can't say it's very clear to me now), really. My questions, since both of them concerns the logic of the application and are supposed to be clean of technical and presentation aspects, what are the advantages of drawing a boundary these two?

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• A Trio of Presentations: Little Wonders, StyleCop, and LINQ/Lambdas

  - by James Michael Hare

  This week is a busy week for me.  First of all I’m giving another presentation on a LINQ/Lambda primer for the rest of the developers in my company.  Of Lambdas and LINQ View more presentations from BlackRabbitCoder Then this Saturday the 25th of June I’ll be reprising my Little Wonders presentation for the Kansas City Developers Camp.  If you are in the area I highly recommend attending and seeing the other great presentations as well.  Their link is here. Little Wonders View more presentations from BlackRabbitCoder Finally, this Monday the 27th I’ll be speaking at the Saint Louis .NET Users group, giving my Automating Code Standards Using StyleCop and FxCop presentation.  If you are in the Saint Louis area stop by!  There’s two other simultaneous presentations as well if they’re more suited to your interests.  The link for the SLDNUG is here. Automating C# Coding Standards using StyleCop and FxCop View more presentations from BlackRabbitCoder Tweet Technorati Tags: C#,.NET,LINQ,Lambda,StyleCop,FxCop,Little Wonders

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• Good DBAs Do Baselines

  - by Louis Davidson

  One morning, you wake up and feel funny. You can’t quite put your finger on it, but something isn’t quite right. What now? Unless you happen to be a hypochondriac, you likely drag yourself out of bed, get on with the day and gather more “evidence”. You check your symptoms over the next few days; do you feel the same, better, worse? If better, then great, it was some temporal issue, perhaps caused by an allergic reaction to some suspiciously spicy chicken. If the same or worse then you go to the doctor for some health advice, but armed with some data to share, and having ruled out certain possible causes that are fixed with a bit of rest and perhaps an antacid. Whether you realize it or not, in comparing how you feel one day to the next, you have taken baseline measurements. In much the same way, a DBA uses baselines to gauge the gauge health of their database servers. Of course, while SQL Server is very willing to share data regarding its health and activities, it has almost no idea of the difference between good and bad. Over time, experienced DBAs develop “mental” baselines with which they can gauge the health of their servers almost as easily as their own body. They accumulate knowledge of the daily, natural state of each part of their database system, and so know instinctively when one of their databases “feels funny”. Equally, they know when an “issue” is just a passing tremor. They see their SQL Server with all of its four CPU cores running close 100% and don’t panic anymore. Why? It’s 5PM and every day the same thing occurs when the end-of-day reports, which are very CPU intensive, are running. Equally, they know when they need to respond in earnest when it is the first time they have heard about an issue, even if it has been happening every day. Nevertheless, no DBA can retain mental baselines for every characteristic of their systems, so we need to collect physical baselines too. In my experience, surprisingly few DBAs do this very well. Part of the problem is that SQL Server provides a lot of instrumentation. If you look, you will find an almost overwhelming amount of data regarding user activity on your SQL Server instances, and use and abuse of the available CPU, I/O and memory. It seems like a huge task even to work out which data you need to collect, let alone start collecting it on a regular basis, managing its storage over time, and performing detailed comparative analysis. However, without baselines, though, it is very difficult to pinpoint what ails a server, just by looking at a single snapshot of the data, or to spot retrospectively what caused the problem by examining aggregated data for the server, collected over many months. It isn’t as hard as you think to get started. You’ve probably already established some troubleshooting queries of the type SELECT Value FROM SomeSystemTableOrView. Capturing a set of baseline values for such a query can be as easy as changing it as follows: INSERT into BaseLine.SomeSystemTable (value, captureTime) SELECT Value, SYSDATETIME() FROM SomeSystemTableOrView; Of course, there are monitoring tools that will collect and manage this baseline data for you, automatically, and allow you to perform comparison of metrics over different periods. However, to get yourself started and to prove to yourself (or perhaps the person who writes the checks for tools) the value of baselines, stick something similar to the above query into an agent job, running every hour or so, and you are on your way with no excuses! Then, the next time you investigate a slow server, and see x open transactions, y users logged in, and z rows added per hour in the Orders table, compare to your baselines and see immediately what, if anything, has changed!

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• What Counts For a DBA: Fitness

  - by Louis Davidson

  If you know me, you can probably guess that physical exercise is not really my thing. There was a time in my past when it a larger part of my life, but even then never in the same sort of passionate way as a number of our SQL friends.  For me, I find that mental exercise satisfies what I believe to be the same inner need that drives people to run farther than I like to drive on most Saturday mornings, and it is certainly just as addictive. Mental fitness shares many common traits with physical fitness, especially the need to attain it through repetitive training. I only wish that mental training burned off a bacon cheeseburger in the same manner as does jogging around a dewy park on Saturday morning. In physical training, there are at least two goals, the first of which is to be physically able to do a task. The second is to train the brain to perform the task without thinking too hard about it. No matter how long it has been since you last rode a bike, you will be almost certainly be able to hop on and start riding without thinking about the process of pedaling or balancing. If you’ve never ridden a bike, you could be a physics professor /Olympic athlete and still crash the first few times you try, even though you are as strong as an ox and your knowledge of the physics of bicycle riding makes the concept child’s play. For programming tasks, the process is very similar. As a DBA, you will come to know intuitively how to backup, optimize, and secure database systems. As a data programmer, you will work to instinctively use the clauses of Transact-SQL DML so that, when you need to group data three ways (and not four), you will know to use the GROUP BY clause with GROUPING SETS without resorting to a search engine.  You have the skill. Making it naturally then requires repetition and experience is the primary requirement, not just simply learning about a topic. The hardest part of being really good at something is this difference between knowledge and skill. I have recently taken several informative training classes with Kimball University on data warehousing and ETL. Now I have a lot more knowledge about designing data warehouses than before. I have also done a good bit of data warehouse designing of late and have started to improve to some level of proficiency with the theory. Yet, for all of this head knowledge, it is still a struggle to take what I have learned and apply it to the designs I am working on.  Data warehousing is still a task that is not yet deeply ingrained in my brain muscle memory. On the other hand, relational database design is something that no matter how much or how little I may get to do it, I am comfortable doing it. I have done it as a profession now for well over a decade, I teach classes on it, and I also have done (and continue to do) a lot of mental training beyond the work day. Sometimes the training is just basic education, some reading blogs and attending sessions at PASS events.  My best training comes from spending time working on other people’s design issues in forums (though not nearly as much as I would like to lately). Working through other people’s problems is a great way to exercise your brain on problems with which you’re not immediately familiar. The final bit of exercise I find useful for cultivating mental fitness for a data professional is also probably the nerdiest thing that I will ever suggest you do.  Akin to running in place, the idea is to work through designs in your head. I have designed more than one database system that would revolutionize grocery store operations, sales at my local Target store, the ordering process at Amazon, and ways to improve Disney World operations to get me through a line faster (some of which they are starting to implement without any of my help.) Never are the designs truly fleshed out, but enough to work through structures and processes.  On “paper”, I have designed database systems to catalog things as trivial as my Lego creations, rental car companies and my audio and video collections. Once I get the database designed mentally, sometimes I will create the database, add some data (often using Red-Gate’s Data Generator), and write a few queries to see if a concept was realistic, but I will rarely fully flesh out the database since I have no desire to do any user interface programming anymore.  The mental training allows me to keep in practice for when the time comes to do the work I love the most for real…even if I have been spending most of my work time lately building data warehouses.  If you are really strong of mind and body, perhaps you can mix a mental run with a physical run; though don’t run off of a cliff while contemplating how you might design a database to catalog the trees on a mountain…that would be contradictory to the purpose of both types of exercise.

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• Declaring interface in the same file as the base class, is it a good practice?

  - by Louis Rhys

  To be interchangable and testable, normally services with logic needs to have interface, e.g. public class FooService: IFooService { ... } Design-wise, I agree with this, but one of the things that bothers me with this approach is that for one service you will need to declare two things (the class and the interface), and in our team, normally two files (one for the class and one for the interface). Another discomfort is the difficulty in navigation because using "Go to definition" in IDE (VS2010) will point to the interface (since other classes refer to the interface), not the actual class. I was thinking that writing IFooService in the same file as FooService will reduce the above weirdness. After all, IFooService and FooService are very related. Is this a good practice? Is there a good reason that IFooService must be located in its own file?

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• How to update dependency during runtime in my .NET application?

  - by Louis Rhys

  I have a server-client application. Sometimes the server is updated which requires some DLLs in the client to be updated as well (The DLLs are the dependencies of the main executable). For now, we have to close the client, manually deploy the DLLs, and then start the client again. This is kind of an inconvenience because the client is an automated application, so normally it doesn't need any user intervention. Is it possible for this to be done automatically without restart or user intervention? Like, the client would download the latest DLL, and replace the current one?

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• What Counts For a DBA – Depth

  - by Louis Davidson

  SQL Server offers very simple interfaces to many of its features. Most people could open up SSMS, connect to a server, write a simple query and see the results. Even several of the core DBA tasks are deceptively straightforward. It doesn’t take a rocket scientist to perform a basic database backup or run a trace (even using the newfangled Extended Events!). However, appearances can be deceptive, and often times it is really important that a DBA understands not just the basics of how to perform a task, but why we do a task, and how that task works. As an analogy, consider a child walking into a darkened room. Most would know that they need to turn on the light, and how to do it, so they flick the switch. But what happens if light fails to shine forth. Most would immediately tell you that you need to consider changing the light bulb. So you hop in the car and take them to the local home store and instruct them to buy a replacement. Confronted with a 40 foot display of light bulbs, how will they decide which of the hundreds of types of bulbs, of different types, fittings, shapes, colors, power and efficiency ratings, is the right choice? Obviously the main lesson the child is going to learn this day is how to use their cell phone as a flashlight so they don’t have to ask for help the next time. Likewise, when the metaphorical toddlers who use your database server have issues, they will instinctively know something is wrong, and may even have some idea what caused it, but will have no depth of knowledge to figure out the right solution. That is where the DBA comes in and attempts to save the day. However, when one looks beneath the shiny UI, SQL Server has its own “40 foot display of light bulbs”, in the form of the tremendous number of tools and the often-bewildering amount of information they can present to the DBA, to help us find issues. Unfortunately, resorting to guesswork, to trying different “bulbs” over and over, hoping to stumble on the answer. This is where the right depth of knowledge goes a long way. If we need to write a SELECT statement, then knowing the syntax and where to find the data is not enough. Knowledge of indexes and query plans is essential. Without it, we might hit on a query that “works”, but we are basically still a user, not a programmer, because we have no real control over our platform. Is that level of knowledge deep enough? Probably not, since knowledge of the underlying metadata and structures would be very useful in helping us make sense of any query plan. Understanding the structure of an index makes the “key lookup” operator not sound like what you do when someone tapes your car key to the ceiling. So is even this level of understanding deep enough? Do we need to understand the memory architecture used to process the query? It might be a comforting level of knowledge, and will doubtless come in handy at some point, but is not strictly necessary in most cases. Beyond that lies (more or less) full knowledge of SQL language and the intricacies of every step the SQL Server engine takes to process our query. My personal theory is that, as a professional, our knowledge of a given task should extend, at a minimum, one level deeper than is strictly necessary to perform the task. Anything deeper can be left to the ridiculously smart, or obsessive, or both. As an example. tasked with storing an integer value between 0 and 99999999, it’s essential that I know that choosing an Integer over Decimal(8,0) will likely offer performance benefits. It is then useful that I also understand the value of adding a CHECK constraint, to make sure the values are valid to the desired range; and comforting that I know a little about the underlying processors, registers and computer math. Anything further, I leave to the likes of Joe Chang, whose recent blog post on the topic offers depth by the bucketful!  

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• 12.10 blue screen, desktop environnement does not load

  - by louis

  just upgraded to Ubuntu 12.10. I can't reach the desktop, it is stuck on the blue screen, the desktop environnement does not load. Can you help please? config: thinkpad T400, 6 GB of Ram, graphic card: Intel Gma 4500Mhd lspci | grep VGA 00:02.0 VGA compatible controller: Intel Corporation Mobile 4 Series Chipset Integrated Graphics Controller (rev 07) I am not sure I have not messed up lightdm / gdm previously...

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• BIOS Always Freezes Instantly

  - by Louis

  I'm not sure if this is necessarily a Ubuntu question, but I've only had the problem since I installed 12.10. When I turn my computer on, the BIOS screen comes up as usual and... nothing else. When I press any key, I hear a loud beep and there's no response. I've tried looking for similar problems, but in most cases people are at least able to interact with their BIOS even if their OS doesn't load. It seems as though it's just completely freezing as soon as I turn it on.

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• Boilerplate Terms & Conditions for web app? [closed]

  - by Louis Bataillard

  Possible Duplicate: What are some good resources for generating privacy policies and terms of use? I am just about done creating my first web application. Since the application stores some user data, I want to make sure that I can not be held liable should something bad happen to the site. I googled around but I could only find boilerplate T&Cs for websites, not for web apps. Does anybody know where I can find such a boilerplate agreement that I can use? I realize that this won't be 100% security, but it's better than nothing I suppose.

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• Disable XP disk check using FAT32

  - by mike xie

  Right now I'm using Windows XP and Macintosh on my MacBook Pro via Bootcamp. Sometimes my XP would crash and when I restarted it it would have to go through disk check, although it says I can skip it by pushing a key, but this never worked for me. I did a bit of research online on how to disable disk check and found chkntfs /x c: but when I tried this out in my cmd it said the disk is FAT32 format. I tried to convert my C: drive from FAT32 to NTFS by using convert c: /FS:NTFS but when I tried this it told me to locate my C: drive. I tried to type C: and Bootcamp but couldn't really get past it. I later saw someone said to use this: Windows Registry Editor Version 5.00 [HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager] "AutoChkTimeOut"=dword:0000000 [HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager] "BootExecute"=hex(7):61,00,75,00,74,00,6f,00,63,00,68,00,65,00,63,00,6b,00,20,\ 00,61,00,75,00,74,00,6f,00,63,00,68,00,6b,00,20,00,2a,00,00,00,00,00 [HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon] "SFCScan"=dword:00000000 [HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\MyComputer\cleanuppath] @=hex(2):25,00,53,00,79,00,73,00,74,00,65,00,6d,00,52,00,6f,00,6f,00,74,00,25,\ 00,5c,00,73,00,79,00,73,00,74,00,65,00,6d,00,33,00,32,00,5c,00,63,00,6c,00,\ 65,00,61,00,6e,00,6d,00,67,00,72,00,2e,00,65,00,78,00,65,00,20,00,2f,00,44,\ 00,20,00,25,00,63,00,00,00 (Save it as .reg and execute it) I have just tried running it but am not really sure if it did anything (my laptop hasn't crashed yet :) ) Firstly, I am wondering if someone can tell me how to check if that script worked? Secondly, if that script didn't work, does anyone have any solution for these problems? Is there another way to disable disk check or is there another way for me to change my FAT32 to NTFS?

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• How to invoke a command using specific proxy server?

  - by Xiè Jìléi

  Some applications support proxy (http proxy or socks proxy), and some are not. For browsers, I can specify proxy server in the preferences/options dialog, and other applications may be able to configure proxy servers in config files. For general purpose, can I invoke a command using a specific proxy? Like following: $ proxy-exec --type sock5 --server 1.2.3.4:8000 -- wget/ftp ... I'm using Ubuntu Maverick. P.S. In win32, it can be implemented by hijacking the socket dlls, maybe, I'm not familiar with Linux programming, but I guess it's possible in Linux. though.

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• Generating wildcard SSL certificate

  - by Xiè Jìléi

  I can make a single SSL certificate for several different domain names: www1.example.com www2.example.com www3.example.com But *.example.com doesn't work. How can I make a single SSL certificate for all sub domains within .example.com? P.S. Here is the extension part of the generated certificate: X509v3 extensions: X509v3 Basic Constraints: CA:FALSE X509v3 Key Usage: Digital Signature, Non Repudiation, Key Encipherment X509v3 Subject Alternative Name: DNS:*.example.com It's simply not matched by any sub-domain under example.com by the browser.

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