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  • On Writing Blogs

    - by Tony Davis
    Why are so many blogs about IT so difficult to read? Over at SQLServerCentral.com, we do a special subscription-only newsletter called Database Weekly. Every other week, it is my turn to look through all the blogs, news and events that might be of relevance to people working with databases. We provide the title, with the link, and a short abstract of what you can expect to read. It is a popular service with close to a million subscribers. You might think that this is a happy and fascinating task. Sometimes, yes. If a blog comes to the point quickly, and says something both interesting and original, then it has our immediate attention. If it backs up what it says with supporting material, then it is more-or-less home and dry, featured in DBW's list. If it also takes trouble over the formatting and presentation, maybe with an illustration or two and any code well-formatted, then we are agog with joy and it is marked as a must-visit destination in our blog roll. More often, however, a task that should be fun becomes a routine chore, and the effort of trawling so many badly-written blogs is enough to make any conscientious Health & Safety officer whistle through their teeth at the risk to the editor's spiritual and psychological well-being. And yet, frustratingly, most blogs could be improved very easily. There is, I believe, a simple formula for a successful blog. First, choose a single topic that is reasonably fresh and interesting. Second, get to the point quickly; explain in the first paragraph exactly what the blog is about, and then stay on topic. In writing the first paragraph, you must picture yourself as a pilot, hearing the smooth roar of the engines as your plane gracefully takes air. Too often, however, the accompanying sound is that of the engine stuttering before the plane veers off the runway into a field, and a wheel falls off. The author meanders around the topic without getting to the point, and takes frequent off-radar diversions to talk about themselves, or the weather, or which friends have recently tagged them. This might work if you're J.D Salinger, or James Joyce, but it doesn't help a technical blog. Sometimes, the writing is so convoluted that we are entirely defeated in our quest to shoehorn its meaning into a simple summary sentence. Finally, write simply, in plain English, and in a conversational way such that you can read it out loud, and sound natural. That's it! If you could also avoid any references to The Matrix then this is a bonus but is purely personal preference. Cheers, Tony.

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  • A Plea for Plain English

    - by Tony Davis
    The English language has, within a lifetime, emerged as the ubiquitous 'international language' of scientific, political and technical communication. On the one hand, learning a single, common language, International English, has made it much easier to participate in and adopt new technologies; on the other hand it must be exasperating to have to use English at international conferences, or on community sites, when your own language has a long tradition of scientific and technical usage. It is also hard to master the subtleties of using a foreign language to explain advanced ideas. This requires English speakers to be more considerate in their writing. Even if you’re used to speaking English, you may be brought up short by this sort of verbiage… "Business Intelligence delivering actionable insights is becoming more critical in the enterprise, and these insights require large data volumes for trending and forecasting" It takes some imagination to appreciate the added hassle in working out what it means, when English is a language you only use at work. Try, just to get a vague feel for it, using Google Translate to translate it from English to Chinese and back again. "Providing actionable business intelligence point of view is becoming more and more and more business critical, and requires that these insights and projected trends in large amounts of data" Not easy eh? If you normally use a different language, you will need to pause for thought before finally working out that it really means … "Every Business Intelligence solution must be able to help companies to make decisions. In order to detect current trends, and accurately predict future ones, we need to analyze large volumes of data" Surely, it is simple politeness for English speakers to stop peppering their writing with a twisted vocabulary that renders it inaccessible to everyone else. It isn’t just the problem of writers who use long words to give added dignity to their prose. It is the use of Colloquial English. This changes and evolves at a dizzying rate, adding new terms and idioms almost daily; it is almost a new and separate language. By contrast, ‘International English', is gradually evolving separately, at its own, more sedate, pace. As such, all native English speakers need to make an effort to learn, and use it, switching from casual colloquial patter into a simpler form of communication that can be widely understood by different cultures, even if it gives you less credibility on the street. Simple-Talk is based, at least in part, on the idea that technical articles can be written simply and clearly in a form of English that can be easily understood internationally, and that they can be written, with a little editorial help, by anyone, and read by anyone, regardless of their native language. Cheers, Tony.

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  • Fair Comments

    - by Tony Davis
    To what extent is good code self-documenting? In one of the most entertaining sessions I saw at the recent PASS summit, Jeremiah Peschka (blog | twitter) got a laugh out of a sleepy post-lunch audience with the following remark: "Some developers say good code is self-documenting; I say, get off my team" I silently applauded the sentiment. It's not that all comments are useful, but that I mistrust the basic premise that "my code is so clearly written, it doesn't need any comments". I've read many pieces describing the road to self-documenting code, and my problem with most of them is that they feed the myth that comments in code are a sign of weakness. They aren't; in fact, used correctly I'd say they are essential. Regardless of how far intelligent naming can get you in describing what the code does, or how well any accompanying unit tests can explain to your fellow developers why it works that way, it's no excuse not to document fully the public interfaces to your code. Maybe I just mixed with the wrong crowd while learning my favorite language, but when I open a stored procedure I lose the will even to read it unless I see a big Phil Factor- or Jeff Moden-style header summarizing in plain English what the code does, how it fits in to the broader application, and a usage example. This public interface describes the high-level process and should explain the role of the code, clearly, for fellow developers, language non-experts, and even any non-technical stake holders in the project. When you step into the body of the code, the low-level details, then I agree that the rules are somewhat different; especially when code is subject to frequent refactoring that can quickly render comments redundant or misleading. At their worst, here, inline comments are sticking plaster to cover up the scars caused by poor naming conventions, failure in clarity when mapping a complex domain into code, or just by not entirely understanding the problem (/ this is the clever part). If you design and refactor your code carefully so that it is as simple as possible, your functions do one thing only, you avoid having two completely different algorithms in the same piece of code, and your functions, classes and variables are intelligently named, then, yes, the need for inline comments should be minimal. And yet, even given this, I'd still argue that many languages (T-SQL certainly being one) just don't lend themselves to readability when performing even moderately-complex tasks. If the algorithm is complex, I still like to see the occasional helpful comment. Please, therefore, be as liberal as you see fit in the detail of the comments you apply to this editorial, for like code it is bound to increase its' clarity and usefulness. Cheers, Tony.

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  • Music before bells and whistles

    - by Tony Davis
    Why is it that Windows has so much difficulty in finding content on its file system? This is not an insurmountable technical problem; on my laptop, I have a database within which I can instantly find text or names within millions of records, within 300 milliseconds. I have a copy of Google Desktop that can find phrases within emails or documents, almost as quickly. It is an important, though mundane, part of an operating system to be able to find files. The first thing I notice within Windows is that the facility to find files or text within files is called 'search' rather than 'find'. Hmm. This doesn’t bode well. What’s this? It does a brute-force search for file names? Here we are in an age when we can breed mice that glow in the dark, and manufacture computers that fit in our shirt pockets, and we find an operating system that is still entirely innocent of managing and indexing content in hierarchical data. I can actually read the files of my PC into a database, mimic the directory/folder hierarchies and then find files in a flash; but when I do the same with Windows Vista, we are suddenly back in a 1960s time warp. Finding files based on their name is bad enough, but finding files based on the content that they contain is more or less asking for an opportunity to wait 20 minutes in order to see a "file not found" message. Sadly, with Windows 7, Microsoft seems to have fallen into the familiar trap of adding bells and whistles before finishing the song. It's certainly true that Microsoft has added new features and a certain polish to Windows Search 4.0, the latest incarnation. It works more like a web search and offers a new search syntax, called Advanced Query Syntax, which allows you to search on file author, file size, date ranges (e.g. date:=7/4/09still does not work reliably. I've experienced first-hand its stubborn refusal, despite a full index, to acknowledge the existence of a file I know exists, based on a search for a specific term within that file that I know is in there somewhere; a file that Google Desktop search, or old wingrep, finds in seconds. When users hark back to the halcyon days of Windows XP search, you know something is seriously amiss. Shouldn't applications get the functionality right before applying animated menus and Teletubby graphics, or is advancing age making me grumpy? I’d be pleased to hear your views, as always. Cheers, Tony.

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  • Going Metro

    - by Tony Davis
    When it was announced, I confess was somewhat surprised by the striking new "Metro" User Interface for Windows 8, based on Swiss typography, Bauhaus design, tiles, touches and gestures, and the new Windows Runtime (WinRT) API on which Metro apps were to be built. It all seemed to have come out of nowhere, like field mushrooms in the night and seemed quite out-of-character for a company like Microsoft, which has hung on determinedly for over twenty years to its quaint Windowing system. Many were initially puzzled by the lack of support for plug-ins in the "Metro" version of IE10, which ships with Win8, and the apparent demise of Silverlight, Microsoft's previous 'radical new framework'. Win8 signals the end of the road for Silverlight apps in the browser, but then its importance here has been waning for some time, anyway, now that HTML5 has usurped its most compelling use case, streaming video. As Shawn Wildermuth and others have noted, if you're doing enterprise, desktop development with Silverlight then nothing much changes immediately, though it seems clear that ultimately Silverlight will die off in favor of a single WPF/XAML framework that supports those technologies that were pioneered on the phones and tablets. There is a mystery here. Is Silverlight dead, or merely repurposed? The more you look at Metro, the more it seems to resemble Silverlight. A lot of the philosophies underpinning Silverlight applications, such as the fundamentally asynchronous nature of the design, have moved wholesale into Metro, along with most the Microsoft Silverlight dev team. As Simon Cooper points out, "Silverlight developers, already used to all the principles of sandboxing and separation, will have a much easier time writing Metro apps than desktop developers". Metro certainly has given the framework formerly known as Silverlight a new purpose. It has enabled Microsoft to bestow on Windows 8 a new "duality", as both a traditional desktop OS supporting 'legacy' Windows applications, and an OS that supports a new breed of application that can share functionality such as search, that understands, and can react to, the full range of gestures and screen-sizes, and has location-awareness. It's clear that Win8 is developed in the knowledge that the 'desktop computer' will soon be a very large, tilted, touch-screen monitor. Windows owes its new-found versatility to the lessons learned from Windows Phone, but it's developed for the big screen, and with full support for familiar .NET desktop apps as well as the new Metro apps. But the old mouse-driven Windows applications will soon look very passé, just as MSDOS character-mode applications did in the nineties. Cheers, Tony.

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  • When done is not done

    - by Tony Davis
    Most developers and DBAs will know what it’s like to be asked to do "a quick tidy up" on a project that, on closer inspection, turns out to be a barely working prototype: as the cynical programmer says, "when you’re told that a project is 90% done, prepare for the next 90%". It is easy to convince a layperson that an application is complete just by using test data, and sticking to the workflow that the development team has implemented and tested. The application is ‘done’ only in the sense that the anticipated paths through the software features, using known data, are fully supported. Reality often strikes only when testers reveal its strange and erratic behavior in response to behavior from the end user that strays from the "ideal". The problem is this: how do we measure progress, accurately and objectively? Development methods such as Scrum or Kanban, when implemented rigorously, can mitigate these problems for developers, to some extent. They force a team to progress one small, but complete feature at a time, to find out how long it really takes for this feature to be "done done"; in other words done to the point where its performance and scalability is understood, it is tested for all conceivable edge cases and doesn’t break…it is ready for prime time. At that point, the team has a much more realistic idea of how long it will take them to really complete all the remaining features, and so how far away the end is. However, it is when software crosses team boundaries that we feel the limitations of such techniques. No matter how well drilled the development team is, problems will still arise if they don’t deploy frequently to a production environment. If they work feverishly for months on end before finally tossing the finished piece of software over the fence for the DBA to deploy to the "real world" then once again will dawn the realization that "done done" is still out of reach, as the DBA uncovers poorly code transactions, un-scalable queries, inefficient caching, and so on. By deploying regularly, end users will also have a much earlier opportunity to tell you how far what you implemented strayed from what they wanted. If you have a tale to tell, anonymized of course, of a "quick polish" project that turned out to be anything but, and what the major problems were, please do share it. Cheers, Tony.

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  • IT Admin for Thrill Seekers

    - by Tony Davis
    A developer suggested to me recently that the life of the DBA was, surely, a dull one. My first reaction was indignation, but quickly followed by the thought that for many people excitement isn't necessarily the most desirable aspect of their job. It's true that some aspects of the DBA role seem guaranteed to quieten the pulse; in the days of tape backups, time must have slowed to eternity for the person whose job it was to oversee this process, placing tapes into secure containers, ensuring correct labeling, and.sorry, I drifted off there for a second. On the other hand, if you follow the adventures of the likes of Brent Ozar or Tom LaRock, you'd be forgiven for thinking that much of a database guy's time is spent, metaphorically, diving through plate glass windows in tight fitting underwear in order to extract grateful occupants from burning database applications. Alas it isn't true of the majority, but it isn't as dull as some people imagine, and is a helter-skelter ride compared with some other IT roles. Every IT department has people who toil away in shadowy corners doing quiet but mysterious tasks. When you ask them to explain what they do, you almost immediately want them to stop, but you hear enough to appreciate that these tasks are often absolutely vital to the smooth functioning of an IT organization. Compared with them, the DBAs are prima donnas. Here are a few nominations: Installation engineer - install all of the company's laptops and workstations, and software, deal with licensing, shipping and data entry.many organizations, especially those subject to tight regulation, would simply grind to a halt without their efforts. Localization engineer - Not quite software engineering, not quite translation, the job is to rebuild a product in a different language and make sure everything still works. QA Tester - firstly, I should say that the testers at Red Gate seem to me some of the most-fulfilled in the company. I refer here to the QA Tester whose job is more-or-less entirely to read a script, click some buttons and make sure the actual and expected values match. Configuration manager - for example, someone whose main job is to configure build environments so that devs can access their source code; assuredly necessary for the smooth functioning and productivity of the team, and hopefully well-paid. So what other sort of job in IT should one choose if the work of a DBA proves to be too exciting? Or are these roles secretly more exciting than many imagine? I invite you all to put forward your own suggestions. Cheers, Tony.

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  • PASS 13 Dispatches: moving to the cloud

    - by Tony Davis
    PASS Summit 13, Day 1 keynote by Quentin Clarke and we're hearing about “redefiniing mission critical in the cloud”. With a move to the Windows Azure cloud comes the promise of capacity on demand, automatic HA, backups, patching and so on, as well as passing responsibility to MS for managing hardware, upgrades and so on. However, for many databases and applications the best route to the cloud is not necessarily obvious. For most, the path of least resistance is IaaS – SQL Server in a Azure VM. It removes the hardware burden but you still have to manage your databases and implementing HA for SQL Server is your responsibility. Also, scaling up comes at quite a cost – the biggest VM (8 CPU cores, 56 GB RAM, 16 1TB drives with 500 IOPS each) weighs in at over over $4500 per month. With PaaS, in the form of Windows SQL Database, you get a “3-copies replica set” so HA comes out-of the box, and removes the majority of the administration burden, but you are moving your database into a very different environment. For a start, it's a shared environment, with other customers using the same compute nodes in the cluster, and potentially even sharing the same database (multi-tenancy). Unless you pay for SQL DB Premium edition, the resources available for your workload will depends on how nicely others “play” in the shared environment. You'll potentially need to do a lot of tuning, and application rewriting to avoid throttling issues, optimising application-database communication to deal with increased latency between the two, and so on. You'll need aggressive application caching. You'll also need retry logic and to deal with (expected) node failure and the need to reconnect. In Tuesday's PASS Summit pre-con from the SQLCAT team, they spent a lot of time covering some of the telemetric techniques (collect into Azure storage the necessary monitoring data) to perform capacity planning, work out the hotspots and bottlenecks in your cloud applications. Tools like WAD (Windows Azure Diagnostics), performance counters SQL Database DMVs, and others, will be essential. Of course, to truly exploit the vast horizontal scaling that is available from the existence of thousands of compute nodes, you'll also need to need to consider how to “shard” your data so Azure can move it between nodes at will. Finding the right path to the Cloud isn't easy, but it's coming. I spoke to people one year ago who saw no real benefit in trying to move their infrastructure and databases to the cloud, but now at their company, it's the conversation that won't go away. Tony.  

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  • New Wine in New Bottles

    - by Tony Davis
    How many people, when their car shows signs of wear and tear, would consider upgrading the engine and keeping the shell? Even if you're cash-strapped, you'll soon work out the subtlety of the economics, the cost of sudden breakdowns, the precious time lost coping with the hassle, and the low 'book value'. You'll generally buy a new car. The same philosophy should apply to database systems. Mainstream support for SQL Server 2005 ends on April 12; many DBAS, if they haven't done so already, will be considering the migration to SQL Server 2008 R2. Hopefully, that upgrade plan will include a fresh install of the operating system on brand new hardware. SQL Server 2008 R2 and Windows Server 2008 R2 are designed to work together. The improved architecture, processing power, and hyper-threading capabilities of modern processors will dramatically improve the performance of many SQL Server workloads, and allow consolidation opportunities. Of course, there will be many DBAs smiling ruefully at the suggestion of such indulgence. This is nothing like the real world, this halcyon place where hardware and software budgets are limitless, development and testing resources are plentiful, and third party vendors immediately certify their applications for the latest-and-greatest platform! As with cars, or any other technology, the justification for a complete upgrade is complex. With Servers, the extra cost at time of upgrade will generally pay you back in terms of the increased performance of your business applications, reduced maintenance costs, training costs and downtime. Also, if you plan and design carefully, it's possible to offset hardware costs with reduced SQL Server licence costs. In his forthcoming SQL Server Hardware book, Glenn Berry describes a recent case where he was able to replace 4 single-socket database servers with one two-socket server, saving about $90K in hardware costs and $350K in SQL Server license costs. Of course, there are exceptions. If you do have a stable, reliable, secure SQL Server 6.5 system that still admirably meets the needs of a specific business requirement, and has no security vulnerabilities, then by all means leave it alone. Why upgrade just for the sake of it? However, as soon as a system shows sign of being unfit for purpose, or is moving out of mainstream support, the ruthless DBA will make the strongest possible case for a belts-and-braces upgrade. We'd love to hear what you think. What does your typical upgrade path look like? What are the major obstacles? Cheers, Tony.

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  • Hype and LINQ

    - by Tony Davis
    "Tired of querying in antiquated SQL?" I blinked in astonishment when I saw this headline on the LinqPad site. Warming to its theme, the site suggests that what we need is to "kiss goodbye to SSMS", and instead use LINQ, a modern query language! Elsewhere, there is an article entitled "Why LINQ beats SQL". The designers of LINQ, along with many DBAs, would, I'm sure, cringe with embarrassment at the suggestion that LINQ and SQL are, in any sense, competitive ways of doing the same thing. In fact what LINQ really is, at last, is an efficient, declarative language for C# and VB programmers to access or manipulate data in objects, local data stores, ORMs, web services, data repositories, and, yes, even relational databases. The fact is that LINQ is essentially declarative programming in a .NET language, and so in many ways encourages developers into a "SQL-like" mindset, even though they are not directly writing SQL. In place of imperative logic and loops, it uses various expressions, operators and declarative logic to build up an "expression tree" describing only what data is required, not the operations to be performed to get it. This expression tree is then parsed by the language compiler, and the result, when used against a relational database, is a SQL string that, while perhaps not always perfect, is often correctly parameterized and certainly no less "optimal" than what is achieved when a developer applies blunt, imperative logic to the SQL language. From a developer standpoint, it is a mistake to consider LINQ simply as a substitute means of querying SQL Server. The strength of LINQ is that that can be used to access any data source, for which a LINQ provider exists. Microsoft supplies built-in providers to access not just SQL Server, but also XML documents, .NET objects, ADO.NET datasets, and Entity Framework elements. LINQ-to-Objects is particularly interesting in that it allows a declarative means to access and manipulate arrays, collections and so on. Furthermore, as Michael Sorens points out in his excellent article on LINQ, there a whole host of third-party LINQ providers, that offers a simple way to get at data in Excel, Google, Flickr and much more, without having to learn a new interface or language. Of course, the need to be generic enough to deal with a range of data sources, from something as mundane as a text file to as esoteric as a relational database, means that LINQ is a compromise and so has inherent limitations. However, it is a powerful and beautifully compact language and one that, at least in its "query syntax" guise, is accessible to developers and DBAs alike. Perhaps there is still hope that LINQ can fulfill Phil Factor's lobster-induced fantasy of a language that will allow us to "treat all data objects, whether Word files, Excel files, XML, relational databases, text files, HTML files, registry files, LDAPs, Outlook and so on, in the same logical way, as linked databases, and extract the metadata, create the entities and relationships in the same way, and use the same SQL syntax to interrogate, create, read, write and update them." Cheers, Tony.

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  • A Community Cure for a String Splitting Headache

    - by Tony Davis
    A heartwarming tale of dogged perseverance and Community collaboration to solve some SQL Server string-related headaches. Michael J Swart posted a blog this week that had me smiling in recognition and agreement, describing how an inquisitive Developer or DBA deals with a problem. It's a three-step process, starting with discomfort and anxiety; a feeling that one doesn't know as much about one's chosen specialized subject as previously thought. It progresses through a phase of intense research and learning until finally one achieves breakthrough, blessed relief and renewed optimism. In this case, the discomfort was provoked by the mystery of massively high CPU when searching Unicode strings in SQL Server. Michael explored the problem via Stack Overflow, Google and Twitter #sqlhelp, finally leading to resolution and a blog post that shared what he learned. Perfect; except that sometimes you have to be prepared to share what you've learned so far, while still mired in the phase of nagging discomfort. A good recent example of this recently can be found on our own blogs. Despite being a loud advocate of the lightning fast T-SQL-based string splitting techniques, honed to near perfection over many years by Jeff Moden and others, Phil Factor retained a dogged conviction that, in theory, shredding element-based XML using XQuery ought to be even more efficient for splitting a string to create a table. After some careful testing, he found instead that the XML way performed and scaled miserably by comparison. Somewhat subdued, and with a nagging feeling that perhaps he was still missing "something", he posted his findings. What happened next was a joy to behold; the community jumped in to suggest subtle changes in approach, using an attribute-based rather than element-based XML list, and tweaking the XQuery shredding. The result was performance and scalability that surpassed all other techniques. I asked Phil how quickly he would have arrived at the real breakthrough on his own. His candid answer was "never". Both are great examples of the power of Community learning and the latter in particular the importance of being brave enough to parade one's ignorance. Perhaps Jeff Moden will accept the string-splitting gauntlet one more time. To quote the great man: you've just got to love this community! If you've an interesting tale to tell about being helped to a significant breakthrough for a problem by the community, I'd love to hear about it. Cheers, Tony.

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  • Aptronyms: fitting the profession to the name

    - by Tony Davis
    Writing a recent piece on the pains of index fragmentation, I found myself wondering why, in SQL Server, you can’t set the equivalent of a fill factor, on a heap table. I scratched my head…who might know? Phil Factor, of course! I approached him with a due sense of optimism only to find that not only did he not know, he also didn’t seem to care much either. I skulked off thinking how this may be the final nail in the coffin of nominative determinism. I’ve always wondered if there was anything in it, though. If your surname is Plumb or Leeks, is there even a tiny, extra percentage chance that you’ll end up fitting bathrooms? Some examples are quite common. I’m sure we’ve all met teachers called English or French, or lawyers called Judge or Laws. I’ve also known a Doctor called Coffin, a Urologist called Waterfall, and a Dentist called Dentith. Two personal favorites are Wolfgang Wolf who ended up managing the German Soccer team, Wolfsburg, and Edmund Akenhead, a Crossword Editor for The Times newspaper. Having forgiven Phil his earlier offhandedness, I asked him for if he knew of any notable examples. He had met the famous Dr. Batty and Dr. Nutter, both Psychiatrists, knew undertakers called Death and Stiff, had read a book by Frederick Page-Turner, and suppressed a giggle at the idea of a feminist called Gurley-Brown. He even managed to better my Urologist example, citing the article on incontinence in the British Journal of Urology (vol.49, pp.173-176, 1977) by A. J. Splatt and D. Weedon. What, however, if you were keen to gently nudge your child down the path to a career in IT? What name would you choose? Subtlety probably doesn’t really work, although in a recent interview, Rodney Landrum did congratulate PowerShell MVP Max Trinidad on being named after a SQL function. Grant “The Memory” Fritchey (OK, I made up that nickname) doesn’t do badly either. Some surnames, seem to offer a natural head start, although I know of no members of the Page-Reid clan in the profession. There are certainly families with the Table surname, although sadly, Little Bobby Tables was merely a legend by xkcd. A member of the well-known Key family would need to name their son Primary, or maybe live abroad, to make their mark. Nominate your examples of people seemingly destined, by name, for their chosen profession (extra points for IT). The best three will receive a prize. Cheers, Tony.

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  • Recovering an Ubuntu installation - Ubuntu eats itself after 'sudo apt-get install -f'

    - by Tony Martin
    Updater (I assume) put a no entry style alert icon on the panel which informed me that certain package dependencies were not up to snuff. Upgrades were thereafter only partial. The dialogue advised that I sudo apt-get install -f. I did this hoping that app-get would fulfil dependencies and replace corrupted files and watched it systematically remove every component of linux, both the stuff I had installed and the core ubuntu packages. I could only assume at this stage that this was in preparation for a fresh install but, of course, I know better now - if you find yourself with apt-get warning you that you are about to remove several hundred packages and asking you to type an involved confirmation string seek advice before proceeding. I digress. This was a 64 bit install of 12.04. All that is left is grub pointing to a couple of windows recovery partitions on the hard drive. Thankfully the Ext4 partition is reachable from a stick boot. EDIT: I've logged onto the machine with a 64 bit stick and can see the file structure left behind by apt-get after {ahem} fixing. My first instinct was to run install from the stick but it seemed to want to do another install rather than a repair. My question then: is there a way to recover the current installation so that if I reinstall the packages I had they will pick up the original settings? I'm particularly worried about losing email from evolution - the rest I could probably lash back together. As for the use of PPA I'm not sure what you're driving at. I generally use Ubuntu Software Centre to install software, though I have used terminal scripts to add new repositories and software successfully following guidance on various websites. The most recent change I made was a downgrade of Wine in an attempt to install and run excel2007 (a necessity, I think, as I have VBA work to do). The installer had stalled and had to be killed. I wonder if that corrupted whatever database holds a model of the package installation structure. I would also be interested to know how this disaster came about. I see people in the know recommending the sudo apt-get install -f as a fairly innocuous cure in similar circumstances. Thanks for your attention, Tony Martin p.s. Do please forgive the rant aspects of the original post. It's hard to write rationally with a large hole in the pit of your stomach.

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  • How does timeseal work? [on hold]

    - by Simon Meyer
    I know the the fics (free internet chess server: www.freechess.org/) does use a program called timeseal to measure the time that a user needed to take a move. This timeseal is some time measurement on the client. Measuring on the client is much better and fairer than measuring the time on the server since you don't lose time just by having a bad connection. But since fics has a lot of interfaces to play on - what prevents rogue interfaces to say that they always only used 0.1 seconds for any move? Does anyone know how this is handled? Just a sidenote: i don't want to build a rogue interface, but i'm trying to build something similar that is measuing client side time but should not be easy to cheat on.

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  • Why don't we just fix Javascript?

    - by Jan Meyer
    Javascript sucks because of a few fatalities well pointed out by Douglas Crockford. We talk a lot about it. But the point here is, why we don't fix it? Coffeescript of course does that and a lot more. But the question here is another: if we provide a webservice that can convert one version of Javascript to the next, and so on, we can keep the language up to date. Such a conversion allows old code to run, albeit with an ever-increasing startup delay, as newer browsers convert old code to the new syntax. To avoid that delay, the site only needs to take the output of the code-transform and paste it in! The effort has immediate benefits for those businesses interested in the results. The rest can sleep tight: their code will continue to run. If we provide backward code-transformation also, then elder browsers can also run ANY new code! Migration scripts should be created by those that make changes to a language. Today they don't, which is in itself a fundamental omission! It should be am obvious part of their job to provide them, as their job isn't really done without them. The onus of making it work should be on them. With this system Any site will be able to run in Any browser, but new code will run best on the newest browsers. This way we reap the benefit of an up-to-date and productive development environment, where today we suffer, supposedly because of yesterday. This is a misconception. We are all trapped in committee-thinking, and we drag along things that only worsen our performance over time! We cause an ever increasing complexity that is hard to underestimate. Javascript is easily fixed. The fact is we don't. As an example, I have seen Patrick Michaud tackle the migration problem in PmWiki. It included forward migration scripts. Whenever syntax changes were made, a migration script was added to transform pages to the new syntax. As far as I know, ALL migrations have worked flawlessly. In other words, we don't tackle the migration problem, we just drag it along. We are incompetent! And why is that? Because technically incompetent people feel they must decide for us. Because they are incompetent, fear rules them. They are obnoxiously conservative, and we suffer the consequence of bad leadership. But the competent don't need to play by the same rules. They can (and must) change them. They are the path forward. It is about time to leave the past behind, and pursue the leanest meanest, no, eternal functionality. That would in and of itself revolutionize programming. So, why don't we stop whining and fix programming? Begin with Javascript and change the world. Even if the browser doesn't hook into this system, coders could. So language updaters should take it upon them to provide migration scripts. Once they exist, browsers may take advantage of them.

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  • On the art of self-promotion

    - by Tony Davis
    I attended Brent Ozar's Building the Fastest SQL Servers session at Tech Ed last week, and found myself engulfed in a 'perfect storm' of excellent technical and presentational skills coupled with an astute awareness of the value of promoting one's work. I spend a lot of time at such events talking to developers and DBAs about the value of blogging and writing articles, and my impression is that some could benefit from a touch less modesty and a little more self-promotion. I sense a reticence in many would-be writers. Is what I have to say important enough? Haven't far more qualified and established commentators, MVPs and so on, already said it? While it's a good idea to pick reasonably fresh and interesting topics, it's more important not to let such fears lead to writer's block. In the eyes of any future employer, your published writing is an extension of your resume. They will not care that a certain MVP knows how to solve problem x, but they will be very interested to see that you have tackled that same problem, and solved it in your own way, and described the process in your own voice. In your current job, your writing is one of the ways you can express to your peers, and to the organization as a whole, the value of what you contribute. Many Developers and DBAs seem to rely on the idea that their work will speak for itself, and that their skill shines out from it. Unfortunately, this isn't always true. Many Development DBAs, for example, will be painfully aware of the massive effort involved in tuning and adding resilience to rapidly developed applications. However, others in the organization who are unaware of what's involved in getting an application that is 'done' ready for production may dismiss such efforts as fussiness or conservatism. At the dark end of the development cycle, chickens come home to roost, but their droppings tend to land on those trying to clear up the mess. My advice is this: next time you fix a bug or improve the resilience or performance of a database or application, make sure that you use team meetings, informal discussions and so on to ensure that people understand what the problem was and what you had to do to fix it. Use your blog to describe, generally, the process you adopted, the resources you used and the insights that came from your work. Encourage your colleagues to do the same. By spreading the art of self-promotion to everyone involved in an IT project, we get a better idea of the extent of the work and the value of the contribution of all the team members. As always, we'd love to hear what you think. This very week, Simple-talk launches its new blogging platform. If any of this has moved you to 'throw your hat into the ring', drop us a mail at [email protected]. Cheers, Tony.

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  • On the art of self-promotion

    - by Tony Davis
    I attended Brent Ozar’s Building the Fastest SQL Servers session at Tech Ed last week, and found myself engulfed in a ‘perfect storm’ of excellent technical and presentational skills coupled with an astute awareness of the value of promoting one’s work. I spend a lot of time at such events talking to developers and DBAs about the value of blogging and writing articles, and my impression is that some could benefit from a touch less modesty and a little more self-promotion. I sense a reticence in many would-be writers. Is what I have to say important enough? Haven’t far more qualified and established commentators, MVPs and so on, already said it? While it’s a good idea to pick reasonably fresh and interesting topics, it’s more important not to let such fears lead to writer’s block. In the eyes of any future employer, your published writing is an extension of your resume. They will not care that a certain MVP knows how to solve problem x, but they will be very interested to see that you have tackled that same problem, and solved it in your own way, and described the process in your own voice. In your current job, your writing is one of the ways you can express to your peers, and to the organization as a whole, the value of what you contribute. Many Developers and DBAs seem to rely on the idea that their work will speak for itself, and that their skill shines out from it. Unfortunately, this isn’t always true. Many Development DBAs, for example, will be painfully aware of the massive effort involved in tuning and adding resilience to rapidly developed applications. However, others in the organization who are unaware of what’s involved in getting an application that is ‘done’ ready for production may dismiss such efforts as fussiness or conservatism. At the dark end of the development cycle, chickens come home to roost, but their droppings tend to land on those trying to clear up the mess. My advice is this: next time you fix a bug or improve the resilience or performance of a database or application, make sure that you use team meetings, informal discussions and so on to ensure that people understand what the problem was and what you had to do to fix it. Use your blog to describe, generally, the process you adopted, the resources you used and the insights that came from your work. Encourage your colleagues to do the same. By spreading the art of self-promotion to everyone involved in an IT project, we get a better idea of the extent of the work and the value of the contribution of all the team members. As always, we’d love to hear what you think. This very week, Simple-talk launches its new blogging platform. If any of this has moved you to ‘throw your hat into the ring’, drop us a mail at [email protected]. Cheers, Tony.

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  • Cheating on Technical Debt

    - by Tony Davis
    One bad practice guaranteed to cause dismay amongst your colleagues is passing on technical debt without full disclosure. There could only be two reasons for this. Either the developer or DBA didn’t know the difference between good and bad practices, or concealed the debt. Neither reflects well on their professional competence. Technical debt, or code debt, is a convenient term to cover all the compromises between the ideal solution and the actual solution, reflecting the reality of the pressures of commercial coding. The one time you’re guaranteed to hear one developer, or DBA, pass judgment on another is when he or she inherits their project, and is surprised by the amount of technical debt left lying around in the form of inelegant architecture, incomplete tests, confusing interface design, no documentation, and so on. It is often expedient for a Project Manager to ignore the build-up of technical debt, the cut corners, not-quite-finished features and rushed designs that mean progress is satisfyingly rapid in the short term. It’s far less satisfying for the poor person who inherits the code. Nothing sends a colder chill down the spine than the dawning realization that you’ve inherited a system crippled with performance and functional issues that will take months of pain to fix before you can even begin to make progress on any of the planned new features. It’s often hard to justify this ‘debt paying’ time to the project owners and managers. It just looks as if you are making no progress, in marked contrast to your predecessor. There can be many good reasons for allowing technical debt to build up, at least in the short term. Often, rapid prototyping is essential, there is a temporary shortfall in test resources, or the domain knowledge is incomplete. It may be necessary to hit a specific deadline with a prototype, or proof-of-concept, to explore a possible market opportunity, with planned iterations and refactoring to follow later. However, it is a crime for a developer to build up technical debt without making this clear to the project participants. He or she needs to record it explicitly. A design compromise made in to order to hit a deadline, be it an outright hack, or a decision made without time for rigorous investigation and testing, needs to be documented with the same rigor that one tracks a bug. What’s the best way to do this? Ideally, we’d have some kind of objective assessment of the level of technical debt in a software project, although that smacks of Science Fiction even as I write it. I’d be interested of hear of any methods you’ve used, but I’m sure most teams have to rely simply on the integrity of their colleagues and the clear perceptions of the project manager… Cheers, Tony.

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  • Where should you put constants and why?

    - by Tim Meyer
    In our mostly large applications, we usually have a only few locations for constants: One class for GUI and internal contstants (Tab Page titles, Group Box titles, calculation factors, enumerations) One class for database tables and columns (this part is generated code) plus readable names for them (manually assigned) One class for application messages (logging, message boxes etc) The constants are usually separated into different structs in those classes. In our C++ applications, the constants are only defined in the .h file and the values are assigned in the .cpp file. One of the advantages is that all strings etc are in one central place and everybody knows where to find them when something must be changed. This is especially something project managers seem to like as people come and go and this way everybody can change such trivial things without having to dig into the application's structure. Also, you can easily change the title of similar Group Boxes / Tab Pages etc at once. Another aspect is that you can just print that class and give it to a non-programmer who can check if the captions are intuitive, and if messages to the user are too detailed or too confusing etc. However, I see certain disadvantages: Every single class is tightly coupled to the constants classes Adding/Removing/Renaming/Moving a constant requires recompilation of at least 90% of the application (Note: Changing the value doesn't, at least for C++). In one of our C++ projects with 1500 classes, this means around 7 minutes of compilation time (using precompiled headers; without them it's around 50 minutes) plus around 10 minutes of linking against certain static libraries. Building a speed optimized release through the Visual Studio Compiler takes up to 3 hours. I don't know if the huge amount of class relations is the source but it might as well be. You get driven into temporarily hard-coding strings straight into code because you want to test something very quickly and don't want to wait 15 minutes just for that test (and probably every subsequent one). Everybody knows what happens to the "I will fix that later"-thoughts. Reusing a class in another project isn't always that easy (mainly due to other tight couplings, but the constants handling doesn't make it easier.) Where would you store constants like that? Also what arguments would you bring in order to convince your project manager that there are better concepts which also comply with the advantages listed above? Feel free to give a C++-specific or independent answer. PS: I know this question is kind of subjective but I honestly don't know of any better place than this site for this kind of question. Update on this project I have news on the compile time thing: Following Caleb's and gbjbaanb's posts, I split my constants file into several other files when I had time. I also eventually split my project into several libraries which was now possible much easier. Compiling this in release mode showed that the auto-generated file which contains the database definitions (table, column names and more - more than 8000 symbols) and builds up certain hashes caused the huge compile times in release mode. Deactivating MSVC's optimizer for the library which contains the DB constants now allowed us to reduce the total compile time of your Project (several applications) in release mode from up to 8 hours to less than one hour! We have yet to find out why MSVC has such a hard time optimizing these files, but for now this change relieves a lot of pressure as we no longer have to rely on nightly builds only. That fact - and other benefits, such as less tight coupling, better reuseability etc - also showed that spending time splitting up the "constants" wasn't such a bad idea after all ;-)

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  • On the art of self-promotion

    - by Tony Davis
    I attended Brent Ozar's Building the Fastest SQL Servers session at Tech Ed last week, and found myself engulfed in a 'perfect storm' of excellent technical and presentational skills coupled with an astute awareness of the value of promoting one's work. I spend a lot of time at such events talking to developers and DBAs about the value of blogging and writing articles, and my impression is that some could benefit from a touch less modesty and a little more self-promotion. I sense a reticence in many would-be writers. Is what I have to say important enough? Haven't far more qualified and established commentators, MVPs and so on, already said it? While it's a good idea to pick reasonably fresh and interesting topics, it's more important not to let such fears lead to writer's block. In the eyes of any future employer, your published writing is an extension of your resume. They will not care that a certain MVP knows how to solve problem x, but they will be very interested to see that you have tackled that same problem, and solved it in your own way, and described the process in your own voice. In your current job, your writing is one of the ways you can express to your peers, and to the organization as a whole, the value of what you contribute. Many Developers and DBAs seem to rely on the idea that their work will speak for itself, and that their skill shines out from it. Unfortunately, this isn't always true. Many Development DBAs, for example, will be painfully aware of the massive effort involved in tuning and adding resilience to rapidly developed applications. However, others in the organization who are unaware of what's involved in getting an application that is 'done' ready for production may dismiss such efforts as fussiness or conservatism. At the dark end of the development cycle, chickens come home to roost, but their droppings tend to land on those trying to clear up the mess. My advice is this: next time you fix a bug or improve the resilience or performance of a database or application, make sure that you use team meetings, informal discussions and so on to ensure that people understand what the problem was and what you had to do to fix it. Use your blog to describe, generally, the process you adopted, the resources you used and the insights that came from your work. Encourage your colleagues to do the same. By spreading the art of self-promotion to everyone involved in an IT project, we get a better idea of the extent of the work and the value of the contribution of all the team members. As always, we'd love to hear what you think. This very week, Simple-talk launches its new blogging platform. If any of this has moved you to 'throw your hat into the ring', drop us a mail at [email protected]. Cheers, Tony.

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  • Data Model Dissonance

    - by Tony Davis
    So often at the start of the development of database applications, there is a premature rush to the keyboard. Unless, before we get there, we’ve mapped out and agreed the three data models, the Conceptual, the Logical and the Physical, then the inevitable refactoring will dog development work. It pays to get the data models sorted out up-front, however ‘agile’ you profess to be. The hardest model to get right, the most misunderstood, and the one most neglected by the various modeling tools, is the conceptual data model, and yet it is critical to all that follows. The conceptual model distils what the business understands about itself, and the way it operates. It represents the business rules that govern the required data, its constraints and its properties. The conceptual model uses the terminology of the business and defines the most important entities and their inter-relationships. Don’t assume that the organization’s understanding of these business rules is consistent or accurate. Too often, one department has a subtly different understanding of what an entity means and what it stores, from another. If our conceptual data model fails to resolve such inconsistencies, it will reduce data quality. If we don’t collect and measure the raw data in a consistent way across the whole business, how can we hope to perform meaningful aggregation? The conceptual data model has more to do with business than technology, and as such, developers often regard it as a worthy but rather arcane ceremony like saluting the flag or only eating fish on Friday. However, the consequences of getting it wrong have a direct and painful impact on many aspects of the project. If you adopt a silo-based (a.k.a. Domain driven) approach to development), you are still likely to suffer by starting with an incomplete knowledge of the domain. Even when you have surmounted these problems so that the data entities accurately reflect the business domain that the application represents, there are likely to be dire consequences from abandoning the goal of a shared, enterprise-wide understanding of the business. In reading this, you may recall experiences of the consequence of getting the conceptual data model wrong. I believe that Phil Factor, for example, witnessed the abandonment of a multi-million dollar banking project due to an inadequate conceptual analysis of how the bank defined a ‘customer’. We’d love to hear of any examples you know of development projects poleaxed by errors in the conceptual data model. Cheers, Tony

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  • pae kernel required for my cpu [closed]

    - by Edward Meyer
    Possible Duplicate: How can I install 12.04 on a non-PAE CPU? (error “Kernel requires features not present on the CPU: PAE”) Virtualbox install 12.04 guest: “pae not present” After loading ubuntu-12.04.1-desktop-i386.iso into my Oracle VM, the hard drive would not boot because the version for my cpu require the pae kernel. How do I insert the pae kernel or download a copy of ubuntu with the pae kernel?

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  • From NaN to Infinity...and Beyond!

    - by Tony Davis
    It is hard to believe that it was once possible to corrupt a SQL Server Database by storing perfectly normal data values into a table; but it is true. In SQL Server 2000 and before, one could inadvertently load invalid data values into certain data types via RPC calls or bulk insert methods rather than DML. In the particular case of the FLOAT data type, this meant that common 'special values' for this type, namely NaN (not-a-number) and +/- infinity, could be quite happily plugged into the database from an application and stored as 'out-of-range' values. This was like a time-bomb. When one then tried to query this data; the values were unsupported and so data pages containing them were flagged as being corrupt. Any query that needed to read a column containing the special value could fail or return unpredictable results. Microsoft even had to issue a hotfix to deal with failures in the automatic recovery process, caused by the presence of these NaN values, which rendered the whole database inaccessible! This problem is history for those of us on more current versions of SQL Server, but its ghost still haunts us. Recently, for example, a developer on Red Gate’s SQL Response team reported a strange problem when attempting to load historical monitoring data into a SQL Server 2005 database via the C# ADO.NET provider. The ratios used in some of their reporting calculations occasionally threw out NaN or infinity values, and the subsequent attempts to load these values resulted in a nasty error. It turns out to be a different manifestation of the same problem. SQL Server 2005 still does not fully support the IEEE 754 standard for floating point numbers, in that the FLOAT data type still cannot handle NaN or infinity values. Instead, they just added validation checks that prevent the 'invalid' values from being loaded in the first place. For people migrating from SQL Server 2000 databases that contained out-of-range FLOAT (or DATETIME etc.) data, to SQL Server 2005, Microsoft have added to the latter's version of the DBCC CHECKDB (or CHECKTABLE) command a DATA_PURITY clause. When enabled, this will seek out the corrupt data, but won’t fix it. You have to do this yourself in what can often be a slow, painful manual process. Our development team, after a quizzical shrug of the shoulders, simply decided to represent NaN and infinity values as NULL, and move on, accepting the minor inconvenience of not being able to tell them apart. However, what of scientific, engineering and other applications that really would like the luxury of being able to both store and access these perfectly-reasonable floating point data values? The sticking point seems to be the stipulation in the IEEE 754 standard that, when NaN is compared to any other value including itself, the answer is "unequal" (i.e. FALSE). This is clearly different from normal number comparisons and has repercussions for such things as indexing operations. Even so, this hardly applies to infinity values, which are single definite values. In fact, there is some encouraging talk in the Connect note on this issue that they might be supported 'in the SQL Server 2008 timeframe'. If didn't happen; SQL 2008 doesn't support NaN or infinity values, though one could be forgiven for thinking otherwise, based on the MSDN documentation for the FLOAT type, which states that "The behavior of float and real follows the IEEE 754 specification on approximate numeric data types". However, the truth is revealed in the XPath documentation, which states that "…float (53) is not exactly IEEE 754. For example, neither NaN (Not-a-Number) nor infinity is used…". Is it really so hard to fix this problem the right way, and properly support in SQL Server the IEEE 754 standard for the floating point data type, NaNs, infinities and all? Oracle seems to have managed it quite nicely with its BINARY_FLOAT and BINARY_DOUBLE types, so it is technically possible. We have an enterprise-class database that is marketed as being part of an 'integrated' Windows platform. Absurdly, we have .NET and XPath libraries that fully support the standard for floating point numbers, and we can't even properly store these values, let alone query them, in the SQL Server database! Cheers, Tony.

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  • It’s the thought that counts…

    - by Tony Davis
    I recently finished editing a book called Tribal SQL, and it was a fantastic experience. It’s a community-sourced book written by first-timers. Fifteen previously unpublished authors contributed one chapter each, with the seemingly simple remit to write about “what makes them passionate about working with SQL Server, something that all SQL Server DBAs and developers really need to know”. Sure, some of the writing skills were a bit rusty as one would expect from busy people, but the ideas and energy were sheer nectar. Any seasoned editor can deal easily with the problem of fixing the output of untrained writers. We can handle with the occasional technical error too, which is why we have technical reviewers. The editor’s real job is to hone the clarity and flow of ideas, making the author’s knowledge and experience accessible to as many others as possible. What the writer needs to bring, on the other hand, is enthusiasm, attention to detail, common sense, and a sense of the person behind the writing. If any of these are missing, no editor can fix it. We can see these essential characteristics in many of the more seasoned and widely-published writers about SQL. To illustrate what I mean by enthusiasm, or passion, take a look at the work of Laerte Junior or Fabiano Amorim. Both authors have English as a second language, but their energy, enthusiasm, sheer immersion in a technology and thirst to know more, drives them, with a little editorial help, to produce articles of far more practical value than one can find in the “manuals”. There’s the attention to detail of the likes of Jonathan Kehayias, or Paul Randal. Read their work and one begins to understand the knowledge coupled with incredible rigor, the willingness to bend and test every piece of advice offered to make sure it’s correct, that marks out the very best technical writing. There’s the common sense of someone like Louis Davidson. All writers, including Louis, like to stretch the grey matter of their readers, but some of the most valuable writing is that which takes a complicated idea, or distils years of experience, and expresses it in a way that sounds like simple common sense. There’s personality and humor. Contrary to what you may have been told, they can and do mix well with technical writing, as long as they don’t become a distraction. Read someone like Rodney Landrum, or Phil Factor, for numerous examples of articles that teach hard technical lessons but also make you smile at least twice along the way. Writing well is not easy and it takes a certain bravery to expose your ideas and knowledge for dissection by others, but it doesn’t mean that writing should be the preserve only of those trained in the art, or best left to the MVPs. I believe that Tribal SQL is testament to the fact that if you have passion for what you do, and really know your topic then, with a little editorial help, you can write, and people will learn from what you have to say. You can read a sample chapter, by Mark Rasmussen, in this issue of Simple-Talk and I hope you’ll consider checking out the book (if you needed any further encouragement, it’s also for a good cause, Computers4Africa). Cheers, Tony  

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  • A temporary disagreement

    - by Tony Davis
    Last month, Phil Factor caused a furore amongst some MVPs with an article that attempted to offer simple advice to developers regarding the use of table variables, versus local and global temporary tables, in their code. Phil makes clear that the table variables do come with some fairly major limitations.no distribution statistics, no parallel query plans for queries that modify table variables.but goes on to suggest that for reasonably small-scale strategic uses, and with a bit of due care and testing, table variables are a "good thing". Not everyone shares his opinion; in fact, I imagine he was rather aghast to learn that there were those felt his article was akin to pulling the pin out of a grenade and tossing it into the database; table variables should be avoided in almost all cases, according to their advice, in favour of temp tables. In other words, a fairly major feature of SQL Server should be more-or-less 'off limits' to developers. The problem with temp tables is that, because they are scoped either in the procedure or the connection, it is easy to allow them to hang around for too long, eating up precious memory and bulking up the shared tempdb database. Unless they are explicitly dropped, global temporary tables, and local temporary tables created within a connection rather than within a stored procedure, will persist until the connection is closed or, with connection pooling, until the connection is reused. It's also quite common with ASP.NET applications to have connection leaks, as Bill Vaughn explains in his chapter in the "SQL Server Deep Dives" book, meaning that the web page exits without closing the connection object, maybe due to an error condition. This will then hang around in the heap for what might be hours before picked up by the garbage collector. Table variables are much safer in this regard, since they are batch-scoped and so are cleaned up automatically once the batch is complete, which also means that they are intuitive to use for the developer because they conform to scoping rules that are closer to those in procedural code. On the surface then, an ideal way to deal with issues related to tempdb memory hogging. So why did Phil qualify his recommendation to use Table Variables? This is another of those cases where, like scalar UDFs and table-valued multi-statement UDFs, developers can sometimes get into trouble with a relatively benign-looking feature, due to way it's been implemented in SQL Server. Once again the biggest problem is how they are handled internally, by the SQL Server query optimizer, which can make very poor choices for JOIN orders and so on, in the absence of statistics, especially when joining to tables with highly-skewed data. The resulting execution plans can be horrible, as will be the resulting performance. If the JOIN is to a large table, that will hurt. Ideally, Microsoft would simply fix this issue so that developers can't get burned in this way; they've been around since SQL Server 2000, so Microsoft has had a bit of time to get it right. As I commented in regard to UDFs, when developers discover issues like with such standard features, the database becomes an alien planet to them, where death lurks around each corner, and they continue to avoid these "killer" features years after the problems have been eventually resolved. In the meantime, what is the right approach? Is it to say "hammers can kill, don't ever use hammers", or is it to try to explain, as Phil's article and follow-up blog post have tried to do, what the feature was intended for, why care must be applied in its use, and so enable developers to make properly-informed decisions, without requiring them to delve deep into the inner workings of SQL Server? Cheers, Tony.

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