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• Head in the Clouds

  - by Tony Davis

  We're just past the second anniversary of the launch of Windows Azure. A couple of years' experience with Azure in the industry has provided some obvious success stories, but has deflated some of the initial marketing hyperbole. As a general principle, Azure seems to work well in providing a Service-Oriented Architecture for services in enterprises that suffer wide fluctuations in demand. Instead of being obliged to provide hardware sufficient for the occasional peaks in demand, one can hire capacity only when it is needed, and the cost of hosting an application is no longer a capital cost. It enables companies to avoid having to scale out hardware for peak periods only to see it underused for the rest of the time. A customer-facing application such as a concert ticketing system, which suffers high demand in short, predictable bursts of activity, is a great example of an application that would work well in Azure. However, moving existing applications to Azure isn't something to be done on impulse. Unless your application is .NET-based, and consists of 'stateless' components that communicate via queues, you are probably in for a lot of redevelopment work. It makes most sense for IT departments who are already deep in this .NET mindset, and who also want 'grown-up' methods of staging, testing, and deployment. Azure fits well with this culture and offers, as a bonus, good Visual Studio integration. The most-commonly stated barrier to porting these applications to Azure is the problem of reconciling the use of the cloud with legislation for data privacy and security. Putting databases in the cloud is a sticky issue for many and impossible for some due to compliance and security issues, the need for direct control over data, and so on. In the face of feedback from the early adopters of Azure, Microsoft has broadened the architectural choices to cater for a wide range of requirements. As well as SQL Azure Database (SAD) and Azure storage, the unstructured 'BLOB and Entity-Attribute-Value' NoSQL storage alternative (which equates more closely with folders and files than a database), Windows Azure offers a wide range of storage options including use of services such as oData: developers who are programming for Windows Azure can simply choose the one most appropriate for their needs. Secondly, and crucially, the Windows Azure architecture allows you the freedom to produce hybrid applications, where only those parts that need cloud-based hosting are deployed to Azure, whereas those parts that must unavoidably be hosted in a corporate datacenter can stay there. By using a hybrid architecture, it will seldom, if ever, be necessary to move an entire application to the cloud, along with personal and financial data. For example that we could port to Azure only put those parts of our ticketing application that capture and process tickets orders. Once an order is captured, the financial side can be processed in our own data center. In short, Windows Azure seems to be a very effective way of providing services that are subject to wide but predictable fluctuations in demand. Have you come to the same conclusions, or do you think I've got it wrong? If you've had experience with Azure, would you recommend it? It would be great to hear from you. Cheers, Tony.

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• Turnkey with LightSwitch

  - by Laila

  Microsoft has long wanted to find a replacement for Microsoft Access. The best attempt yet, which is due out in, or before, September is Visual Studio LightSwitch, with which it is said to be as 'easy as flipping a switch' to use Silverlight to create simple form-driven business applications. It is easy to get confused by the various initiatives from Microsoft. No, this isn't WebMatrix. There is no 'Razor', for this isn't meant for cute little ecommerce sites, but is designed to build simple database-applications of the card-box type. It is more clearly a .NET-based solution to the problem that every business seems to suffer from; the plethora of Access-based, and Excel-based 'private' and departmental database-applications. These are a nightmare for any IT department since they are often 'stealth' applications built by the business in the teeth of opposition from the IT Department zealots. As they are undocumented, it is scarily easy to bring a whole department into disarray by decommissioning a PC tucked under a desk somewhere. With LightSwitch, it is easy to re-write such applications in a standard, maintainable, way, using a SQL Server database, deployed somewhere reasonably safe such as Azure. Even Sharepoint or Windows Communication Foundation can be used as data sources. Oracle's ApEx has taken off remarkably well, and has shaken the perception that, for the business user, Oracle must remain a mystic force accessible only to the priests and acolytes. Microsoft, by comparison had only Access, which was first released in 1992, the year of the Madonna conical bustier. It looks just as dated. Microsoft badly needed an entirely new solution to the same business requirement that led to Access's and Foxpro's long-time popularity, but which had the same allure as ApEx. LightSwitch is sound in its ideas, and comfortingly conventional in its architecture. By giving an easy access to SQL Server databases, and providing a 'thumb and blanket' migration path to Access-heads, LightSwitch seems likely to offer a simple way of pulling more Microsoft users into the .NET community. If Microsoft puts its weight behind it, then it will give some glimmer of hope to the many Silverlight developers that Microsoft is capable of seeing through its .NET revolution.

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• Why enumerator structs are a really bad idea (redux)

  - by Simon Cooper

  My previous blog post went into some detail as to why calling MoveNext on a BCL generic collection enumerator didn't quite do what you thought it would. This post covers the Reset method. To recap, here's the simple wrapper around a linked list enumerator struct from my previous post (minus the readonly on the enumerator variable): sealed class EnumeratorWrapper : IEnumerator<int> { private LinkedList<int>.Enumerator m_Enumerator; public EnumeratorWrapper(LinkedList<int> linkedList) { m_Enumerator = linkedList.GetEnumerator(); } public int Current { get { return m_Enumerator.Current; } } object System.Collections.IEnumerator.Current { get { return Current; } } public bool MoveNext() { return m_Enumerator.MoveNext(); } public void Reset() { ((System.Collections.IEnumerator)m_Enumerator).Reset(); } public void Dispose() { m_Enumerator.Dispose(); } } If you have a look at the Reset method, you'll notice I'm having to cast to IEnumerator to be able to call Reset on m_Enumerator. This is because the implementation of LinkedList<int>.Enumerator.Reset, and indeed of all the other Reset methods on the BCL generic collection enumerators, is an explicit interface implementation. However, IEnumerator is a reference type. LinkedList<int>.Enumerator is a value type. That means, in order to call the reset method at all, the enumerator has to be boxed. And the IL confirms this: .method public hidebysig newslot virtual final instance void Reset() cil managed { .maxstack 8 L_0000: nop L_0001: ldarg.0 L_0002: ldfld valuetype [System]System.Collections.Generic.LinkedList`1/Enumerator<int32> EnumeratorWrapper::m_Enumerator L_0007: box [System]System.Collections.Generic.LinkedList`1/Enumerator<int32> L_000c: callvirt instance void [mscorlib]System.Collections.IEnumerator::Reset() L_0011: nop L_0012: ret } On line 0007, we're doing a box operation, which copies the enumerator to a reference object on the heap, then on line 000c calling Reset on this boxed object. So m_Enumerator in the wrapper class is not modified by the call the Reset. And this is the only way to call the Reset method on this variable (without using reflection). Therefore, the only way that the collection enumerator struct can be used safely is to store them as a boxed IEnumerator<T>, and not use them as value types at all.

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• Know your Data Lineage

  - by Simon Elliston Ball

  An academic paper without the footnotes isn’t an academic paper. Journalists wouldn’t base a news article on facts that they can’t verify. So why would anyone publish reports without being able to say where the data has come from and be confident of its quality, in other words, without knowing its lineage. (sometimes referred to as ‘provenance’ or ‘pedigree’) The number and variety of data sources, both traditional and new, increases inexorably. Data comes clean or dirty, processed or raw, unimpeachable or entirely fabricated. On its journey to our report, from its source, the data can travel through a network of interconnected pipes, passing through numerous distinct systems, each managed by different people. At each point along the pipeline, it can be changed, filtered, aggregated and combined. When the data finally emerges, how can we be sure that it is right? How can we be certain that no part of the data collection was based on incorrect assumptions, that key data points haven’t been left out, or that the sources are good? Even when we’re using data science to give us an approximate or probable answer, we cannot have any confidence in the results without confidence in the data from which it came. You need to know what has been done to your data, where it came from, and who is responsible for each stage of the analysis. This information represents your data lineage; it is your stack-trace. If you’re an analyst, suspicious of a number, it tells you why the number is there and how it got there. If you’re a developer, working on a pipeline, it provides the context you need to track down the bug. If you’re a manager, or an auditor, it lets you know the right things are being done. Lineage tracking is part of good data governance. Most audit and lineage systems require you to buy into their whole structure. If you are using Hadoop for your data storage and processing, then tools like Falcon allow you to track lineage, as long as you are using Falcon to write and run the pipeline. It can mean learning a new way of running your jobs (or using some sort of proxy), and even a distinct way of writing your queries. Other Hadoop tools provide a lot of operational and audit information, spread throughout the many logs produced by Hive, Sqoop, MapReduce and all the various moving parts that make up the eco-system. To get a full picture of what’s going on in your Hadoop system you need to capture both Falcon lineage and the data-exhaust of other tools that Falcon can’t orchestrate. However, the problem is bigger even that that. Often, Hadoop is just one piece in a larger processing workflow. The next step of the challenge is how you bind together the lineage metadata describing what happened before and after Hadoop, where ‘after’ could be  a data analysis environment like R, an application, or even directly into an end-user tool such as Tableau or Excel. One possibility is to push as much as you can of your key analytics into Hadoop, but would you give up the power, and familiarity of your existing tools in return for a reliable way of tracking lineage? Lineage and auditing should work consistently, automatically and quietly, allowing users to access their data with any tool they require to use. The real solution, therefore, is to create a consistent method by which to bring lineage data from these data various disparate sources into the data analysis platform that you use, rather than being forced to use the tool that manages the pipeline for the lineage and a different tool for the data analysis. The key is to keep your logs, keep your audit data, from every source, bring them together and use the data analysis tools to trace the paths from raw data to the answer that data analysis provides.

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• Software Tuned to Humanity

  - by Phil Factor

  I learned a great deal from a cynical old programmer who once told me that the ideal length of time for a compiler to do its work was the same time it took to roll a cigarette. For development work, this is oh so true. After intently looking at the editing window for an hour or so, it was a relief to look up, stretch, focus the eyes on something else, and roll the possibly-metaphorical cigarette. This was software tuned to humanity. Likewise, a user’s perception of the “ideal” time that an application will take to move from frame to frame, to retrieve information, or to process their input has remained remarkably static for about thirty years, at around 200 ms. Anything else appears, and always has, to be either fast or slow. This could explain why commercial applications, unlike games, simulations and communications, aren’t noticeably faster now than they were when I started programming in the Seventies. Sure, they do a great deal more, but the SLAs that I negotiated in the 1980s for application performance are very similar to what they are nowadays. To prove to myself that this wasn’t just some rose-tinted misperception on my part, I cranked up a Z80-based Jonos CP/M machine (1985) in the roof-space. Within 20 seconds from cold, it had loaded Wordstar and I was ready to write. OK, I got it wrong: some things were faster 30 years ago. Sure, I’d now have had all sorts of animations, wizzy graphics, and other comforting features, but it seems a pity that we have used all that extra CPU and memory to increase the scope of what we develop, and the graphical prettiness, but not to speed the processes needed to complete a business procedure. Never mind the weight, the response time’s great! To achieve 200 ms response times on a Z80, or similar, performance considerations influenced everything one did as a developer. If it meant writing an entire application in assembly code, applying every smart algorithm, and shortcut imaginable to get the application to perform to spec, then so be it. As a result, I’m a dyed-in-the-wool performance freak and find it difficult to change my habits. Conversely, many developers now seem to feel quite differently. While all will acknowledge that performance is important, it’s no longer the virtue is once was, and other factors such as user-experience now take precedence. Am I wrong? If not, then perhaps we need a new school of development technique to rival Agile, dedicated once again to producing applications that smoke the rear wheels rather than pootle elegantly to the shops; that forgo skeuomorphism, cute animation, or architectural elegance in favor of the smell of hot rubber. I struggle to name an application I use that is truly notable for its blistering performance, and would dearly love one to do my everyday work – just as long as it doesn’t go faster than my brain.

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• New features in SQL Prompt 6.4

  - by Tom Crossman

  We’re pleased to announce a new beta version of SQL Prompt. We’ve been trying out a few new core technologies, and used them to add features and bug fixes suggested by users on the SQL Prompt forum and suggestions forum. You can download the SQL Prompt 6.4 beta here (zip file). Let us know what you think! New features Execute current statement In a query window, you can now execute the SQL statement under your cursor by pressing Shift + F5. For example, if you have a query containing two statements and your cursor is placed on the second statement: When you press Shift + F5, only the second statement is executed:   Insert semicolons You can now use SQL Prompt to automatically insert missing semicolons after each statement in a query. To insert semicolons, go to the SQL Prompt menu and click Insert Semicolons. Alternatively, hold Ctrl and press B then C. BEGIN…END block highlighting When you place your cursor over a BEGIN or END keyword, SQL Prompt now automatically highlights the matching keyword: Rename variables and aliases You can now use SQL Prompt to rename all occurrences of a variable or alias in a query. To rename a variable or alias, place your cursor over an instance of the variable or alias you want to rename and press F2: Improved loading dialog box The database loading dialog box now shows actual progress, and you can cancel loading databases:   Single suggestion improvement SQL Prompt no longer suggests keywords if the keyword has been typed and no other suggestions exist. Performance improvement SQL Prompt now has less impact on Management Studio start up time. What do you think? We want to hear your feedback about the beta. If you have any suggestions, or bugs to report, tell us on the SQL Prompt forum or our suggestions forum.

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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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• Hadoop, NOSQL, and the Relational Model

  - by Phil Factor

  (Guest Editorial for the IT Pro/SysAdmin Newsletter)Whereas Relational Databases fit the world of commerce like a glove, it is useless to pretend that they are a perfect fit for all human endeavours. Although, with SQL Server, we’ve made great strides with indexing text, in processing spatial data and processing markup, there is still a problem in dealing efficiently with large volumes of ephemeral semi-structured data. Key-value stores such as Cassandra, Project Voldemort, and Riak are of great value for ephemeral data, and seem of equal value as a data-feed that provides aggregations to an RDBMS. However, the Document databases such as MongoDB and CouchDB are ideal for semi-structured data for which no fixed schema exists; analytics and logging are obvious examples. NoSQL products, such as MongoDB, tackle the semi-structured data problem with panache. MongoDB is designed with a simple document-oriented data model that scales horizontally across multiple servers. It doesn’t impose a schema, and relies on the application to enforce the data structure. This is another take on the old ‘EAV’ problem (where you don’t know in advance all the attributes of a particular entity) It uses a clever replica set design that allows automatic failover, and uses journaling for data durability. It allows indexing and ad-hoc querying. However, for SQL Server users, the obvious choice for handling semi-structured data is Apache Hadoop. There will soon be an ODBC Driver for Apache Hive .and an Add-in for Excel. Additionally, there are now two Hadoop-based connectors for SQL Server; the Apache Hadoop connector for SQL Server 2008 R2, and the SQL Server Parallel Data Warehouse (PDW) connector. We can connect to Hadoop process the semi-structured data and then store it in SQL Server. For one steeped in the culture of Relational SQL Databases, I might be expected to throw up my hands in the air in a gesture of contempt for a technology that was, judging by the overblown journalism on the subject, about to make my own profession as archaic as the Saggar makers bottom knocker (a potter’s assistant who helped the saggar maker to make the bottom of the saggar by placing clay in a metal hoop and bashing it). However, on the contrary, I find that I'm delighted with the advances made by the NoSQL databases in the past few years. Having the flow of ideas from the NoSQL providers will knock any trace of complacency out of the providers of Relational Databases and inspire them into back-fitting some features, such as horizontal scaling, with sharding and automatic failover into SQL-based RDBMSs. It will do the breed a power of good to benefit from all this lateral thinking.

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• Advice on CSS you'll wish your mother told you

  William Brewer turns a jaundiced eye to the task of laying out web pages using CSS, and gives some nuggets from years of occasional page design. It is, of course, set with a a stylesheet he's come up with to demo a few of his points.

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• TSQL formatting - a sure fire way to start a conversation.

  - by fatherjack

  There are probably as many opinions on ways to format code as there are people writing code and I am not here to say that any one is better than any other. Well, that isn't true. I am here to say that one way is better than another but this isn't a matter of preference or personal taste, this is an example of where sloppy formatting can cause TSQL to weird and whacky things but following some simple methods can make your code more reliable and more robust when . Take these two pieces of code, ready...(read more)

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• Obscure SPUtility.SendMail Behavior When Manually Passing in Mail Headers

  - by Damon

  There are two ways to send mail in SharePoint: you can either use the mail components from the System.Net namespace, or you can send email using SharePoint's SPUtility.SendMail method.  One of the benefits of the SPUtility.SendMail method is that it uses the mail configuration from SharePoint, so you can manage settings in Central Administration instead of having to go through and modify your web.config file.  SPUtility.SendMail can get the job done, but it's defiantly not as developer friendly as the components from the System.Net namespace.  If you want to CC someone on an email, for example, you do NOT have a nice CC parameter - you have to manually add the CC mail header and pass it into the SPUtility.SendMail method.  I had to do this the other day, and ran into a really obscure issue. If you do NOT pass the headers into the method then SharePoint sends the email using the From Address configured in the Outgoing Mail settings in Central Admin.  If you pass headers into the method, but do not include the from header, then SharePoint sends the mail using the email address of the current user. This can be an issue if your mail server is setup to reject an email from an invalid email address or an email address that is not on your domain.  The way to fix this issue is to always pass in the from header.  If you want to use the configured From address, then you can do the following: SPWebApplication webApp = SPWebApplication.Lookup(new Uri(SPContext.Current.Site.Url)); StringDictionary headers = new StringDictionary(); headers.Add("from", webApp.OutboundMailSenderAddress);

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• Backing up Exchange 2010 For Free

  It's hardly surprising that many SysAdmins are willing to pay over the odds for sophisticated backup solutions which they don't necessarily need, just to make sure their data is safe ASAP. Thankfully, Antoine Khater is here to give you a short and sweet walkthrough on how to keep your Exchange 2010 Server backed up for free. And the best news? You've already got everything you need.

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• Getting the right results with bcp and DTS with multiple versions of SQL Server installed.

  - by fatherjack

  I was using SSIS for the first time on an instance the other day and came across this error when I executed a package Package migration from version 3 to version 2 failed with error 0xC001700A. The version number in the package is not valid. The version number cannot be greater than current version number. This was a pain and wasn't something that I was expecting, however, the error message made sense - the package was being executed by the wrong version of the executable. Not impossible to...(read more)

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• A Knights Tale

  - by Phil Factor

  There are so many lessons to be learned from the story of Knight Capital losing nearly half a billion dollars as a result of a deployment gone wrong. The Knight Capital Group (KCG N) was an American global financial services firm engaging in market making, electronic execution, and institutional sales and trading. According to the recent order (File No.3.15570) against Knight Capital by U.S. Securities and Exchange Commission?, Knight had, for many years used some software which broke up incoming “parent” orders into smaller “child” orders that were then transmitted to various exchanges or trading venues for execution. A tracking ‘cumulative quantity’ function counted the number of ‘child’ orders and stopped the process once the total of child orders matched the ‘parent’ and so the parent order had been completed. Back in the mists of time, some code had been added to it  which was excuted if a particular flag was set. It was called ‘power peg’ and seems to have had a similar design and purpose, but, one guesses, would have shared the same tracking function. This code had been abandoned in 2003, but never deleted. In 2005, The tracking function was moved to an earlier point in the main process. It would seem from the account that, from that point, had that flag ever been set, the old ‘Power Peg’ would have been executed like Godzilla bursting from the ice, making child orders without limit without any tracking function. It wasn’t, presumably because the software that set the flag was removed. In 2012, nearly a decade after ‘Power Peg’ was abandoned, Knight prepared a new module to their software to cope with the imminent Retail Liquidity Program (RLP) for the New York Stock Exchange. By this time, the flag had remained unused and someone made the fateful decision to reuse it, and replace the old ‘power peg’ code with this new RLP code. Had the two actions been done together in a single automated deployment, and the new deployment tested, all would have been well. It wasn’t. To quote… “Beginning on July 27, 2012, Knight deployed the new RLP code in SMARS in stages by placing it on a limited number of servers in SMARS on successive days. During the deployment of the new code, however, one of Knight’s technicians did not copy the new code to one of the eight SMARS computer servers. Knight did not have a second technician review this deployment and no one at Knight realized that the Power Peg code had not been removed from the eighth server, nor the new RLP code added. Knight had no written procedures that required such a review.” (para 15) “On August 1, Knight received orders from broker-dealers whose customers were eligible to participate in the RLP. The seven servers that received the new code processed these orders correctly. However, orders sent with the repurposed flag to the eighth server triggered the defective Power Peg code still present on that server. As a result, this server began sending child orders to certain trading centers for execution. Because the cumulative quantity function had been moved, this server continuously sent child orders, in rapid sequence, for each incoming parent order without regard to the number of share executions Knight had already received from trading centers. Although one part of Knight’s order handling system recognized that the parent orders had been filled, this information was not communicated to SMARS.” (para 16) SMARS routed millions of orders into the market over a 45-minute period, and obtained over 4 million executions in 154 stocks for more than 397 million shares. By the time that Knight stopped sending the orders, Knight had assumed a net long position in 80 stocks of approximately $3.5 billion and a net short position in 74 stocks of approximately $3.15 billion. Knight’s shares dropped more than 20% after traders saw extreme volume spikes in a number of stocks, including preferred shares of Wells Fargo (JWF) and semiconductor company Spansion (CODE). Both stocks, which see roughly 100,000 trade per day, had changed hands more than 4 million times by late morning. Ultimately, Knight lost over $460 million from this wild 45 minutes of trading. Obviously, I’m interested in all this because, at one time, I used to write trading systems for the City of London. Obviously, the US SEC is in a far better position than any of us to work out the failings of Knight’s IT department, and the report makes for painful reading. I can’t help observing, though, that even with the breathtaking mistakes all along the way, that a robust automated deployment process that was ‘all-or-nothing’, and tested from soup to nuts would have prevented the disaster. The report reads like a Greek Tragedy. All the way along one wants to shout ‘No! not that way!’ and ‘Aargh! Don’t do it!’. As the tragedy unfolds, the audience weeps for the players, trapped by a cruel fate. All application development and deployment requires defense in depth. All IT goes wrong occasionally, but if there is a culture of defensive programming throughout, the consequences are usually containable. For financial systems, these defenses are required by statute, and ignored only by the foolish. Knight’s mistakes weren’t made by just one hapless sysadmin, but were progressive errors by an  IT culture spanning at least ten years.  One can spell these out, but I think they’re obvious. One can only hope that the industry studies what happened in detail, learns from the mistakes, and draws the right conclusions.

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• Documentation and Test Assertions in Databases

  - by Phil Factor

  When I first worked with Sybase/SQL Server, we thought our databases were impressively large but they were, by today’s standards, pathetically small. We had one script to build the whole database. Every script I ever read was richly annotated; it was more like reading a document. Every table had a comment block, and every line would be commented too. At the end of each routine (e.g. procedure) was a quick integration test, or series of test assertions, to check that nothing in the build was broken. We simply ran the build script, stored in the Version Control System, and it pulled everything together in a logical sequence that not only created the database objects but pulled in the static data. This worked fine at the scale we had. The advantage was that one could, by reading the source code, reach a rapid understanding of how the database worked and how one could interface with it. The problem was that it was a system that meant that only one developer at the time could work on the database. It was very easy for a developer to execute accidentally the entire build script rather than the selected section on which he or she was working, thereby cleansing the database of everyone else’s work-in-progress and data. It soon became the fashion to work at the object level, so that programmers could check out individual views, tables, functions, constraints and rules and work on them independently. It was then that I noticed the trend to generate the source for the VCS retrospectively from the development server. Tables were worst affected. You can, of course, add or delete a table’s columns and constraints retrospectively, which means that the existing source no longer represents the current object. If, after your development work, you generate the source from the live table, then you get no block or line comments, and the source script is sprinkled with silly square-brackets and other confetti, thereby rendering it visually indigestible. Routines, too, were affected. In our system, every routine had a directly attached string of unit-tests. A retro-generated routine has no unit-tests or test assertions. Yes, one can still commit our test code to the VCS but it’s a separate module and teams end up running the whole suite of tests for every individual change, rather than just the tests for that routine, which doesn’t scale for database testing. With Extended properties, one can get the best of both worlds, and even use them to put blame, praise or annotations into your VCS. It requires a lot of work, though, particularly the script to generate the table. The problem is that there are no conventional names beyond ‘MS_Description’ for the special use of extended properties. This makes it difficult to do splendid things such ensuring the integrity of the build by running a suite of tests that are actually stored in extended properties within the database and therefore the VCS. We have lost the readability of database source code over the years, and largely jettisoned the use of test assertions as part of the database build. This is not unexpected in view of the increasing complexity of the structure of databases and number of programmers working on them. There must, surely, be a way of getting them back, but I sometimes wonder if I’m one of very few who miss them.

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• SQL Excursions

  - by Grant Fritchey

  Not everyone likes boats. Some people like hanging out, on dry land, maybe sipping a good wine. Interested in doing that AND learning some new stuff about SQL Server? Then you might want to check out SQL Excursions. Denny Cherry (blog|twitter), MVP and terribly sharp individual, has organized this new venture to supply small group training in combination with travel to interesting, and let's face it, comfortable, places. The first trip is already set for Napa Valley. The training will be by Denny and MVP, author, and all round great guy, Thomas LaRock (blog|twitter). Seats for this unique event are going fast. I'd suggest signing up soon. Oh, and did I forget to mention that Red Gate is sponsoring dinner at a fine restaurant? Well, consider it mentioned. Seriously, nice wine, great training, beautiful scenery, networking, all in one place. What are you waiting for?

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• Improving Comparison Operators and Window Functions

  It is dangerous to assume that your data is sound. SQL already has intrinsic ways to cope with missing, or unknown data in its comparison predicate operators, or Theta operators. Can SQL be more effective in the way it deals with data quality? Joe Celko describes how the SQL Standard could soon evolve to deal with data in ways that allow aggregation and windowing in cases where the data quality is less than perfect

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• Antenna Aligner Part 4: Role'ing in the deep

  - by Chris George

  Since last time I've been trying to sort out the general workflow of the app. It's fundamentally not hard, there is a list of transmitters, you select a transmitter and it shows the compass view. Having done quite a bit of ajax/asp.net/html in the past, I immediately started off by creating two divs within my 'page', one for the list, one for the compass. Then using the onClick event in the list, this will switch the display attribute on the divs. This seemed to work, but did lead to some dodgy transitional redrawing artefacts which I was not happy with. So after some Googling I realised I was doing it all wrong! JQuery mobile has the concept of giving an object in html a data-role. By giving a div the attribute data-role="page" it is then treated as a separate page on the mobile device. Within the code, this is referenced like a html anchor in the form #mypage. Using this system, page transitions such as fade or slide are automatically applied which adds to the whole authenticity of the app! Here is a simple example: . <a href="#'compasspage">compass</a> . <div data-role="page" id="compasspage" data-add-back-btn="true"> But I don't want just a static link, I want to dynamically create my list, and get each list elements to switch to the compass page with the right information. So here is the jquery that I used to dynamically inject new <li> rows into the <ul> block. $('ul').append($('<li/>', {    //here appendin `<li>`     'data-role': "list-divider" }).append($('<a/>', {    //here appending `<a>` into `<li>`     'href': '#compasspage',     'data-transition': 'none',     'onclick': 'selectTx(' + i + ')',     'html': buttonHtml }))); $('ul').listview('refresh'); This is called within a for loop so the first 5 appropriate transmitters are used. There are several things of interest to note here. Firstly, I could not find a more elegant way to tell the target page which transmitter I've clicked on, so I have used the onclick event as well as the href attribute. The onclick event fires 'selectTx' which simply sets a global member variable to the specific index number I've clicked on. Yes it's not nice, but it works. Secondly, the data-transition attribute is set to 'none'. I wanted the transition between the pages to be a whooshy slidey effect. However this worked going to the compass page, but returning to the list page gave some undesirable visual artefacts (flickering, redrawing etc.). So I decided to remove the transitions all together, which was a shame. Thirdly, rather than embedding loads of html into the append command, I removed this out into a variable 'buttonHtml'. Doing this really tidied up my code. Until next time!

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• The Birth of SSAS Compare

  - by Red Gate Software BI Tools Team

  Noemi Moreno, Red Gate Business Intelligence Specialist Software vendors – even Microsoft – tend to forget about the needs of business intelligence developers. We are a rare and rather invisible species. For example, BIDS remained in VS 2008 until SQL Server 2012. It took until this release before we got something as simple as an “undo” function. Before I joined Red Gate as a BI specialist, I worked on SQL Development. I’ll never forget the time I discovered Red Gate’s SQL Compare tool and how it reduced the task of preparing a database release from a couple of days to ten minutes. When I moved to SSAS, MDX and cubes, I became frustrated with the deployment process because I couldn’t find a tool that made Cube releases as easy as they are with SQL Compare. This became my quest. I pitched the idea to a few people in Red Gate’s regular Down Tools Week, when everyone puts down their day-to-day tasks and works on their own projects. My task was to reason with a roomful of cynical developers, hardened to the blandishments of project managers, for help to develop a tool that would compare two different SSAS databases and create the script to process only the objects that needed processing, thereby reducing release time to only a few minutes. I walked to the podium and gave them the full story of the distressed BI specialists, doomed to spend tedious hours preparing deployment scripts. A few developers recovered from their torpor to cast a languid eye at my presentation. It wasn’t enough. In a sudden impulse, I blurted out a promise to perform a flamenco dance for just the team if the tool was able to successfully compare two SSAS databases and generate a script by the end of the week. I was lucky enough that some of them believed me and jumped in: David Pond (Dev), Matt Burton (Dev), Tilman Bregler (Dev), Shobana Sekar (Test), Ruchija Raj (Test), Nick Sutherland (Product Manager) and Irma Tanovic (BI). They didn’t know that Irma and I would be away on a conference in Amsterdam and would leave them without our support. But to my surprise, they had a working tool by the time we came back – basic, and with a few bugs, but a working tool nonetheless! Seeing it compare a very basic SSAS database, detect the changes and generate the scripts was amazing! Something that normally takes half a day was done in under a minute. Since then, a few months have passed and a BI Tools team has been created at Red Gate to work full time on BI tools for BI developers, starting with SSAS Compare. How cool is that? So download the free beta and give us your feedback. And the flamenco? I still need to deliver that. Tilman reminds me every day! I need to get the full flamenco costume.

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• How much is a subscriber worth?

  - by Tom Lewin

  This year at Red Gate, we’ve started providing a way to back up SQL Azure databases and Azure storage. We decided to sell this as a service, instead of a product, which means customers only pay for what they use. Unfortunately for us, it makes figuring out revenue much trickier. With a product like SQL Compare, a customer pays for it, and it’s theirs for good. Sure, we offer support and upgrades, but, fundamentally, the sale is a simple, upfront transaction: we’ve made this product, you need this product, we swap product for money and everyone is happy. With software as a service, it isn’t that easy. The money and product don’t change hands up front. Instead, we provide a service in exchange for a recurring fee. We know someone buying SQL Compare will pay us $X, but we don’t know how long service customers will stay with us, or how much they will spend. How do we find this out? We use lifetime value analysis. What is lifetime value? Lifetime value, or LTV, is how much a customer is worth to the business. For Entrepreneurs has a brilliant write up that we followed to conduct our analysis. Basically, it all boils down to this equation: LTV = ARPU x ALC To make it a bit less of an alphabet-soup and a bit more understandable, we can write it out in full: The lifetime value of a customer equals the average revenue per customer per month, times the average time a customer spends with the service Simple, right? A customer is worth the average spend times the average stay. If customers pay on average $50/month, and stay on average for ten months, then a new customer will, on average, bring in $500 over the time they are a customer! Average spend is easy to work out; it’s revenue divided by customers. The problem comes when we realise that we don’t know exactly how long a customer will stay with us. How can we figure out the average lifetime of a customer, if we only have six months’ worth of data? The answer lies in the fact that: Average Lifetime of a Customer = 1 / Churn Rate The churn rate is the percentage of customers that cancel in a month. If half of your customers cancel each month, then your average customer lifetime is two months. The problem we faced was that we didn’t have enough data to make an estimate of one month’s cancellations reliable (because barely anybody cancels)! To deal with this data problem, we can take data from the last three months instead. This means we have more data to play with. We can still use the equation above, we just need to multiply the final result by three (as we worked out how many three month periods customers stay for, and we want our answer to be in months). Now these estimates are likely to be fairly unreliable; when there’s not a lot of data it pays to be cautious with inference. That said, the numbers we have look fairly consistent, and it’s super easy to revise our estimates when new data comes in. At the very least, these numbers give us a vague idea of whether a subscription business is viable. As far as Cloud Services goes, the business looks very viable indeed, and the low cancellation rates are much more than just data points in LTV equations; they show that the product is working out great for our customers, which is exactly what we’re looking for!

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• Accessing SQL Server data from iOS apps

  - by RobertChipperfield

  Almost all mobile apps need access to external data to be valuable. With a huge amount of existing business data residing in Microsoft SQL Server databases, and an ever-increasing drive to make more and more available to mobile users, how do you marry the rather separate worlds of Microsoft's SQL Server and Apple's iOS devices? The classic answer: write a web service layer Look at any of the questions on this topic asked in Internet discussion forums, and you'll inevitably see the answer, "just write a web service and use that!". But what does this process gain? For a well-designed database with a solid security model, and business logic in the database, writing a custom web service on top of this just to access some of the data from a different platform seems inefficient and unnecessary. Desktop applications interact with the SQL Server directly - why should mobile apps be any different? The better answer: the iSql SDK Working along the lines of "if you do something more than once, make it shared," we set about coming up with a better solution for the general case. And so the iSql SDK was born: sitting between SQL Server and your iOS apps, it provides the simple API you're used to if you've been developing desktop apps using the Microsoft SQL Native Client. It turns out a web service remained a sensible idea: HTTP is much more suited to the Big Bad Internet than SQL Server's native TDS protocol, removing the need for complex configuration, firewall configuration, and the like. However, rather than writing a web service for every app that needs data access, we made the web service generic, serving only as a proxy between the SQL Server and a client library integrated into the iPhone or iPad app. This client library handles all the network communication, and provides a clean API. OSQL in 25 lines of code As an example of how to use the API, I put together a very simple app that allowed the user to enter one or more SQL statements, and displayed the results in a rather primitively formatted text field. The total amount of Objective-C code responsible for doing the work? About 25 lines. You can see this in action in the demo video. Beta out now - your chance to give us your suggestions! We've released the iSql SDK as a beta on the MobileFoo website: you're welcome to download a copy, have a play in your own apps, and let us know what we've missed using the Feedback button on the site. Software development should be fun and rewarding: no-one wants to spend their time writing boiler-plate code over and over again, so stop writing the same web service code, and start doing exciting things in the new world of mobile data!

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• What Counts for a DBA: Humility

  - by drsql

  In football (the American sort, naturally,) there are a select group of players who really hope to never have their names called during the game. They are members of the offensive line, and their job is to protect other players so they can deliver the ball to the goal to score points. When you do hear their name called, it is usually because they made a mistake and the player that they were supposed to protect ended up flat on his back admiring the clouds in the sky instead of advancing towards the goal to scoring point. Even on the rare occasion their name is called for a good reason, it is usually because they were making up for a teammate who had made a mistake and they covered up for them. The role of offensive lineman is a very good analogy for the role of the admin DBA. As a DBA, you are called on to be barely visible and rarely heard, protecting the company data assets tenaciously, even though the enemies to our craft surround us on all sides:. Developers: Cries of ‘foul!’ often ensue when the DBA says that they want data integrity to be stringently enforced and that documentation is needed so they can support systems, mostly because every error occurrence in the enterprise will be initially blamed on the database and fall to the DBA to troubleshoot. Insisting too loudly may bring those cries of ‘foul’ that somewhat remind you of when your 2 year old daughter didn't want to go to bed. The result of this petulance is that the next "enemy" gets involved. Managers: The concerns that motivate DBAs to argue will not excite the kind of manager who gets his technical knowledge from a glossy magazine filled with buzzwords, charts, and pretty pictures. However, the other programmers in the organization will tickle the buzzword void with a stream of new-sounding ideas and technologies constantly, along with warnings that if we did care about data integrity and document things, the budget would explode! In contrast, the arguments for integrity of data and supportability tend to be about as exciting as watching grass grow, and far too many manager types seem to prefer to smoke it than watch it. Packaged Applications: The DBA is rarely given a chance to review a new application that is being demonstrated for the enterprise, and rarer still is the DBA that gets a veto of an application because the database it uses has clearly been created by an architect that won't read a data modeling book because he is already married. More often than not this leads to hours of work for the DBA trying to performance-tune a database with a menagerie of rules that must be followed to stay within the  application support agreement, such as no changing indexes on a third party schema even though there are 10 billion rows instead of the 10 thousand when the system was last optimized. Hardware Failures: Physical disks, networking devices, memory, and backup devices all come with a measure known as ‘mean time before failure’ and it is never listed in centuries or eons. More like years, and the term ‘mean’ indicates that half of the devices are expected to fail before that, which by my calendar means any hour of any day that it wants to fail it will. But the DBA sucks it up and does the task at hand with a humility that makes them nearly invisible to all but the most observant person in the organization. The best DBAs I know are so proactive in their relentless pursuit of perfection that they detect many of the bugs (which they seldom caused) in the system well before they become a problem. In the end the DBA gets noticed for one of same two reasons as the offensive lineman. You make a mistake, like dropping a critical production database that had never been backed up; or when a system crashes for any reason whatsoever and they are on the spot with troubleshooting and system restoration plans that have been well thought out, tested, and tested again. Not because there is any glory in it, but because it is what they do.   Note: The characteristics of the professions referred to in this blog are meant to be overstated stereotypes for humorous effect, and even some DBAs aren't quite this perfect. If you are reading this far and haven’t hand written a 10 page flaming comment about how you are a _______ and you aren’t like this, that is awesome. Not every situation applies to everyone, but if you have never worked with a bad packaged app, a magazine trained manager, programmers that aren’t team players, or hardware that occasionally failed, relax and go have a unicorn sandwich before you wake up.

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• Defensive Error Handling

  TRY…CATCH error handling in SQL Server has certain limitations and inconsistencies that will trap the unwary developer, used to the more feature-rich error handling of client-side languages such as C# and Java. In this article, abstracted from his excellent new book, Defensive Database Programming with SQL Server, Alex Kuznetsov offers a simple, robust approach to checking and handling errors in SQL Server, with client-side error handling used to enforce what is done on the server.

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• Immersive UX Changing the Face of Retail

  Changing the Face of Retail is an article Ive been thinking about most of the past couple weeks. I think my goal with the article is to one talk about how technology built into the retail environment can be used to build better experiences for customers and 2 to talk about how this kind of evolutionary extension of the retail environment is better for customers AND retailers.I walked into the Microsoft Retail Store or at least one of them, (see one at Mission Vejo or Scottsdale) and its really impressive...Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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• News From EAP Testing

  - by Fatherjack

  There is a phrase that goes something like “Watch the pennies and the pounds/dollars will take care of themselves”, meaning that if you pay attention to the small things then the larger things are going to fare well too. I am lucky enough to be a Friend of Red Gate and once in a while I get told about new features in their tools and have a test copy of the software to trial. I got one of those emails a week or so ago and I have been exploring the SQL Prompt 6 EAP since then. One really useful feature of long standing in SQL Prompt is the idea of a code snippet that is automatically pasted into the SSMS editor when you type a few key letters. For example I can type “ssf” and then press the tab key and the text is expanded to SELECT * FROM. There are lots of these combinations and it is possible to create your own really easily. To create your own you use the Snippet Manager interface to define the shortcut letters and the code that you want to have put in their place. Let’s look at an example. Say I am writing a blog about something and want to have the demo code create a temporary table. It might looks like this; The first time you run the code everything is fine, a lovely set of dates fill the results grid but run it a second time and this happens.   Yep, we didn’t destroy the temporary table so the CREATE statement fails when it finds the table already exists. No matter, I have a snippet created that takes care of this.   Nothing too technical here but you will see that in the Code section there is $CURSOR$, this isn’t a TSQL keyword but a marker for SQL Prompt to place the cursor in that position when the Code is pasted into the SSMS Editor. I just place my cursor above the CREATE statement and type “ifobj” – the shortcut for my code to DROP the temporary table – which has been defined in the Snippet Manager as below. This means I am right-away ready to type the name of the offending table. Pretty neat and it’s been very useful in saving me lots of time over many years.   The news for SQL Prompt 6 is that Red Gate have added a new Snippet Command of $PASTE$. Let’s alter our snippet to the following and try it out   Once again, we will type type “ifobj” in the SSMS Editor but first of all, highlight the name of the table #TestTable and copy it to your clipboard. Now type “ifobj” and press Tab… Wherever the string $PASTE$ is placed in the snippet, the contents of your clipboard are merged into the pasted TSQL. This means I don’t need to type the table name into the code snippet, it’s already there and I am seeing a fully functioning piece of TSQL ready to run. This means it is it even easier to write TSQL quickly and consistently. Attention to detail like this from Red Gate means that their developer tools stay on track to keep winning awards year after year and help take the hard work out of writing neat, accurate TSQL. If you want to try out SQL Prompt all the details are at http://www.red-gate.com/products/sql-development/sql-prompt/.

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