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  • Why should I adopt MVC?

    - by Andrew
    I decided to get my hands wet and got the YII framework for PHP. I created my first application, then created new controller, model and view. Connected to database, got my record passed from controller to the view and printed the hello world. I am confused now. If I have to do the same thing for each page, this seems like a nightmare to me. In each controller I have to do a lot of same operations - declare variables, and pass them to views. I also need to create models for each page and this is all confusing to me. In my idea the main goal of development is to avoid duplication, but what I see here is lots and lots of duplicated code. Please advise and clarify. Maybe you could suggest a good reading about MVC and coding patterns and best practices in MVC. Because so far, it takes much more time to create a small site using MVC than using my own programming schema.

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  • Remove gravity from single body

    - by Siddharth
    I have multiple bodies in my game world in andengine. All the bodies affected by gravity but in that I want my specific body does not affected by the gravity. For that solution after research I found that I have to use body.setGravityScale(0) method for my problem solution. But in my andengine extension I don't found that method so please provide guidance about how get access about that method. Also for the above problem any other guidance will be acceptable. Thank You! I apply following code for reverse gravity final Vector2 vec = new Vector2(0, -SensorManager.GRAVITY_EARTH * bulletBody.getMass()); bulletBody.applyForce(vec, bulletBody.getWorldCenter());

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  • Provocative Tweets From the Dachis Social Business Summit

    - by Mike Stiles
    On June 20, all who follow social business and how social is changing how we do business and internal business structures, gathered in London for the Dachis Social Business Summit. In addition to Oracle SVP Product Development, Reggie Bradford, brands and thought leaders posed some thought-provoking ideas and figures. Here are some of the most oft-tweeted points, and our thoughts that they provoked. Tweet: The winners will be those who use data to improve performance.Thought: Everyone is dwelling on ROI. Why isn’t everyone dwelling on the opportunity to make their product or service better (as if that doesn’t have an effect on ROI)? Big data can improve you…let it. Tweet: High performance hinges on integrated teams that interact with each other.Thought: Team members may work well with each other, but does the team as a whole “get” what other teams are doing? That’s the key to an integrated, companywide workforce. (Internal social platforms can facilitate that by the way). Tweet: Performance improvements come from making the invisible visible.Thought: Many of the factors that drive customer behavior and decisions are invisible. Through social, customers are now showing us what we couldn’t see before…if we’re paying attention. Tweet: Games have continuous feedback, which is why they’re so engaging.  Apply that to business operations.Thought: You think your employees have an obligation to be 100% passionate and engaged at all times about making you richer. Think again. Like customers, they must be motivated. Visible insight that they’re advancing on their goals helps. Tweet: Who can add value to the data?  Data will tend to migrate to where it will be most effective.Thought: Not everybody needs all the data. One team will be able to make sense of, use, and add value to data that may be irrelevant to another team. Like a strategized football play, the data has to get sent to the spot on the field where it’s needed most. Tweet: The sale isn’t the light at the end of the tunnel, it’s the start of a new marketing cycle.Thought: Another reason the ROI question is fundamentally flawed. The sale is not the end of the potential return on investment. After-the-sale service and nurturing begins where the sales “victory” ends. Tweet: A dead sale is one that’s not shared.  People must be incentivized to share.Thought: Guess what, customers now know their value to you as marketers on your behalf. They’ll tell people about your product, but you’ve got to answer, “Why should I?” And you’ve got to answer it with something substantial, not lame trinkets. Tweet: Social user motivations are competition, affection, excellence and curiosity.Thought: Your followers will engage IF; they can get something for doing it, love your culture so much they want you to win, are consistently stunned at the perfection and coolness of your products, or have been stimulated enough to want to know more. Tweet: In Europe, 92% surveyed said they couldn’t care less about brands.Thought: Oh well, so much for loving you or being impressed enough with your products & service that they want you to win. We’ve got a long way to go. Tweet: A complaint is a gift.Thought: Our instinct where complaints are concerned is to a) not listen, b) dismiss the one who complains as a kook, c) make excuses, and d) reassure ourselves with internal group-think that they’re wrong and we’re right. It’s the perfect recipe for how to never, ever grow or get better. In a way, this customer cares more than you do. Tweet: 78% of consumers think peer recommendation is the best form of advertising.  Eventually, engagement is going to eat advertising.Thought: Why is peer recommendation best? Trust. If a friend tells me how great a movie was, I believe him. He has credibility with me. He’s seen it, and he could care less if I buy a ticket. He’s telling me it was awesome because he sincerely believes that it was.  That’s gold. Tweet: 86% of customers are willing to pay more for a better customer experience. Thought: This “how mad can we make our customers without losing them” strategy has to end. The customer experience has actual monetary value, money you’re probably leaving on the table. @mikestilesPhoto: stock.xchng

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  • MySQL for Beginners course - first steps to lowering your Database TCOs

    - by Antoinette O'Sullivan
    Thinking about lowering your Database TCO by using the MySQL Server? Don't miss the chance to get training from the source! With the newly released MySQL for Beginners class, learn how this powerful relational database management system can make your life easier and more fun! This course covers all the basics and will get you on your way, with a solid foundation. This instructor led, hands-on class covers the fundamentals of SQL and relational databases, using MySQL as a teaching tool. Send information about this course release to a friend who might be considering getting started on the world's most popular small footprint database.

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  • PHP and performance

    - by Naif
    I always hear that PHP is for medium and small websites whereas .NET and Java for enterprise applications. My question is about PHP. Why is PHP not a good option for enterprise web applications? Is it because if the web application becomes bigger then PHP will be slower as it is an interpreted language? I know that corporate world will choose .NET or J2EE because of the integration with their products and because of back end services, etc. However, if we just have PHP for building sites and web applications then how can we use it to perform well with big sites? In short, Is there a relationship between the performance of PHP and the size of the website? What are the factors that make PHP not appropriate option for big sites?

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  • Linear search vs Octree (Frustum cull)

    - by Dave
    I am wondering whether I should look into implementing an octree of some kind. I have a very simple game which consists of a 3d plane for the floor. There are multiple objects scattered around on the ground, each one has an aabb in world space. Currently I just do a loop through the list of all these objects and check if its bounding box intersects with the frustum, it works great but I am wondering if if it would be a good investment in an octree. I only have max 512 of these objects on the map and they all contain bounding boxes. I am not sure if an octree would make it faster since I have so little objects in the scene.

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  • Rotating multiple points at once in 2D

    - by Deukalion
    I currently have an editor that creates shapes out of (X, Y) coordinates and then triangulate that to make up a shape of those points. What will I have to do to rotate all of those points simultaneously? Say I click the screen in my editor, it locates the point where I've clicked and if I move the mouse up or down from that point it calculates rotation on X and Y axis depending on new position relevant to first position, say I move up 10 on the Y axis it rotates that way and the same way for X. Or simply, somehow to enter rotation degree: 90, 180, 270, 360, for example. I use VertexPositionColor at the moment. What are the best algorithms or methods that I can look at to rotate multiple points in 2D at once? Also: Since this is an editor I do now want to rotate it on the Matrix, so if I want to rotate the whole shape 180 degree that's the new "position" of all the points, so that's the new rotation = 0 for example. Later on I probably will use World Matrix rotation for this, but not now.

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  • Advice for transitioning into a Java developer position from doing other types of web development?

    - by Rick
    I've been doing web programming and currently work at a company working with mainly PHP and Javascript. For a little while now I've been becoming more and more frustrated with the shortcomings of this type of development and want to move to a company with a more defined development process that values doing things the "right way" such as using Unit tests, dependency injection / IoC, etc. I've been learning JEE / Java as much as I can on my own time but would really like to make a switch to doing this as my career and leave behind the PHP world altogether. I'm just wondering if anyone can give me advice on which things to put my main focus on right now to make myself marketable as an entry level Java developer. Basically, I feel that I'm not really learning anything new at my current job that will benefit me and its only making me more and more frustrated so I figure if there is any way to position myself for a transition I would rather do it sooner than later. Thanks for any advice.

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  • 24 hours of PASS is back!

    - by Sergio Govoni
    The most important free on-line event on SQL Server and Business Intelligence is back! The 24 Hours of PASS is coming back with a great edition fully based on the new features of SQL Server 2014. What could you aspect from the next PASS Summit? Find it out on June 25, 2014 (12:00 GMT) on 24 Hours of PASS: SQL Server 2014! Register now at this link. No matter from what part of the world you will follow the event, the important thing is to know that it will be 24 hours of continuous training on SQL Server and Business Intelligence.

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  • Check for bodies within a specific circle in Box2D

    - by ltjax
    I'm trying to find positions to insert new bodies into my world. For that, I'd like to have a "free" spot where this body wouldn't overlap with anything else. So my plan was to sample "random" positions and check whether they overlap with my "potential" new body. Since my bodies are always circular, I'd need to test within a given circle. So far, the only way to use box2d for this seems to use b2World::QueryAABB around my circle and manually doing an overlap test with all the fixtures it gives me (Box2D doesn't event seem to allow me to tap into its overlapping tests?!). It seems to me like Box2D should already provide such functionality - is there a way that lets me do this without reinventing most of the wheel again?

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  • ISACA Information Security & Risk Management Conference, Nov 14-16

    - by Troy Kitch
    Please join Oracle, as a platinum sponsor, at this year's ISACA Information Security and Risk Management Conference in Las Vegas, Nov 14-16. This year’s conference offers up to 32 CPE hours and is designed to meet the needs of information security, governance, compliance, and risk management professionals. The event builds on and includes the key elements of information security, governance, compliance and risk management practices, and offers a fresh perspective on current and future trends. As provider of the world’s most complete, open, and integrated business software and hardware systems, Oracle can uniquely safeguard your information throughout its entire lifecycle and is the recognized leader in Data Security, Identity Management, and Governance, Risk, and Compliance solutions. Also, attend the Oracle Megatrends Session, Gone in 60 Seconds: Mitigating Database Security Risk and stop by our booth, # 100 & #102, to meet with Oracle Security Solution experts, see live product demos, and more. Learn more and register.

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  • New qeep app for Java ME feature phones: meet qeepy people

    - by hinkmond
    Is it "qeepy" if you meet people by using your cell phone instead of, you know, talking to them? Nah. Not if it's a Java ME cell phone! See: Use Qeep to Meet Peeps Here's a quote: Qeep is a free app, and compatible with over 1,000 Java-enabled feature phones... ... Qeep is one of the world's largest mobile gaming and social discovery platforms. Members of the mobile community can play live multiplayer games; blog photos; send sound attacks, text messages and virtual gifts; and meet new friends worldwide. So, go on. Go, use Qeep on your Java ME feature phone to play multiplayer games, blog photos, and meet new friends worldwide. No one will think that you're weird... Not much, at least. Hinkmond

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  • Are there any Java based libraries that provide game mapping features?

    - by James.Elsey
    Hi All, I'm working on a Java web based game in my spare time (springMVC / JSPs etc), and I'm wondering what are my options for dealing with the "game world" or mapping element. My game will be 2d / text based, so I have no need for any OpenGL / Flash etc. My initial idea was to use Google maps and provide a custom overlay, but I want to know if there are any alternatives? For example, if I create a 2d map with all my zones, are there any libraries that will help me plot players, work out distances and so forth? Regards

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  • Java Developers: Open-source Modules, Great Tools, Opportunity.

    - by Paul Sorensen
    The role of Java developer may just be better than ever. An excellent article in Java Magazine discusses the availability of web-based tools that help development teams more effectively manage their projects and modules. If you are a Java developer you should definitely read this article. I especially like the Expert Opinions scattered throughout the article. These highlight real-world usage of the latest and greatest development tools.  As you consider steps to move your career forward, consider Java certification. Oracle has over 15 unique Java certification credentials available. The process of becoming certified in Java and preparing for your exams will require you to study, learn and practice (code). All of this activity will help you sharpen your skills and increase your working knowledge of Java - making you a better developer and more valuable member of your team. You can use the Certification Finder on the Oracle certification homepage to find a Java certification that is right for you. Thanks! 

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  • Physics from other games

    - by Carlosrdz1
    I'm making a platform engine with XNA Game Studio, and I've solved almost everything about colliding stuff. But now, I'm searching for good physics for the player, I'm trying to emulate characters from other games like Mario from Super Mario World, or MegaMan X... do you know a website or something, where the physics from that games are revealed? I remember seen a page with something like that. Or what's the process you think is the best to emulate physics from other games? Just trial and error? Thank you.

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  • Where should i organize my matrices in a 3D Game engine?

    - by Need4Sleep
    I'm working with a group of people from around the world to create a game engine(and hopefully a game with it) within the next upcoming years. My first task was writing a camera class for the engine to use in order to add cameras to the scene, position and follow points in the scene. The problem i have is with using matrices for transformations in the class, should i keep matrices separate to each class? such as have the model matrix in the model class, camera matrix in the camera class, or have all matrices placed in one class/chuck? I could see pros and cons for each method, but i wanted to hear some input form a more professional standpoint.

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  • Support for non-english characters?

    - by TomJ
    Is support for non-english characters common in programming languages? I mean, technically, I would think it is feasable, but I don't have any experience in anything other than english, so I don't know how common it is. I know that there are non-english based programming languages, but can something like C#, C++, C, Java, or Python support non-english classes/methods/variables? Example in go (url, http://play.golang.org/p/wRYCNVdbjC) package main import "fmt" type ?? struct { ?? string } func main() { fmt.Println("Hello, ??") ?? := new(??) ??.?? = "hello world" fmt.Println(??.??) }

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  • Real performance of node.js

    - by uther.lightbringer
    I've got a question concerning node.js performance. There is quite lot of "benchmarks" and a lot of fuss about great performance of node.js. But how does it stand in real world? Not just process empty request at high speed. If someone could try to compare this scenario: Java (or equivalent) server running an application with complex business logic between receiving request and sending response. How would node.js deal with it? If there was need for a lot of JavaScript processing on server side, is node.js really so fast that it can execute JavaScript, and stand a chance against more heavyveight competitors?

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  • Getting Started with jqChart for ASP.NET Web Forms

    - by jqChart
    Official Site | Samples | Download | Documentation | Forum | Twitter Introduction jqChart takes advantages of HTML5 Canvas to deliver high performance client-side charts and graphs across browsers (IE 6+, Firefox, Chrome, Opera, Safari) and devices, including iOS and Android mobile devices. Some of the key features are: High performance rendering. Animaitons. Scrolling/Zoooming. Support for unlimited number of data series and data points. Support for unlimited number of chart axes. True DateTime Axis. Logarithmic and Reversed axis scale. Large set of chart types - Bar, Column, Pie, Line, Spline, Area, Scatter, Bubble, Radar, Polar. Financial Charts - Stock Chart and Candlestick Chart. The different chart types can be easily combined.  System Requirements Browser Support jqChart supports all major browsers: Internet Explorer - 6+ Firefox Google Chrome Opera Safari jQuery version support jQuery JavaScript framework is required. We recommend using the latest official stable version of the jQuery library. Visual Studio Support jqChart for ASP.NET does not require using Visual Studio. You can use your favourite code editor. Still, the product has been tested with several versions of Visual Studio .NET and you can find the list of supported versions below: Visual Studio 2008 Visual Studio 2010 Visual Studio 2012 ASP.NET Web Forms support Supported version - ASP.NET Web Forms 3.5, 4.0 and 4.5 Installation Download and unzip the contents of the archive to any convenient location. The package contains the following folders: [bin] - Contains the assembly DLLs of the product (JQChart.Web.dll) for WebForms 3.5, 4.0 and 4.5. This is the assembly that you can reference directly in your web project (or better yet, add it to your ToolBox and then drag & drop it from there). [js] - The javascript files of jqChart and jqRangeSlider (and the needed libraries). You need to include them in your ASPX page, in order to gain the client side functionality of the chart. The first file is "jquery-1.5.1.min.js" - this is the official jQuery library. jqChart is built upon jQuery library version 1.4.3. The second file you need is the "excanvas.js" javascript file. It is used from the versions of IE, which dosn't support canvas graphics. The third is the jqChart javascript code itself, located in "jquery.jqChart.min.js". The last one is the jqRangeSlider javascript, located in "jquery.jqRangeSlider.min.js". It is used when the chart zooming is enabled. [css] - Contains the Css files that the jqChart and the jqRangeSlider need. [samples] - Contains some examples that use the jqChart. For full list of samples plese visit - jqChart for ASP.NET Samples. [themes] - Contains the themes shipped with the products. It is used from the jqRangeSlider. Since jqRangeSlider supports jQuery UI Themeroller, any theme compatible with jQuery UI ThemeRoller will work for jqRangeSlider as well. You can download any additional themes directly from jQuery UI's ThemeRoller site available here: http://jqueryui.com/themeroller/ or reference them from Microsoft's / Google's CDN. <link rel="stylesheet" type="text/css" media="screen" href="http://ajax.aspnetcdn.com/ajax/jquery.ui/1.8.21/themes/smoothness/jquery-ui.css" /> The final result you will have in an ASPX page containing jqChart would be something similar to that (assuming you have copied the [js] to the Script folder and [css] to Content folder of your ASP.NET site respectively). <%@ Page Language="C#" AutoEventWireup="true" CodeBehind="Default.aspx.cs" Inherits="samples_cs.Default" %> <%@ Register Assembly="JQChart.Web" Namespace="JQChart.Web.UI.WebControls" TagPrefix="jqChart" %> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html > <head runat="server"> <title>jqChart ASP.NET Sample</title> <link rel="stylesheet" type="text/css" href="~/Content/jquery.jqChart.css" /> <link rel="stylesheet" type="text/css" href="~/Content/jquery.jqRangeSlider.css" /> <link rel="stylesheet" type="text/css" href="~/Content/themes/smoothness/jquery-ui-1.8.21.css" /> <script src="<% = ResolveUrl("~/Scripts/jquery-1.5.1.min.js") %>" type="text/javascript"></script> <script src="<% = ResolveUrl("~/Scripts/jquery.jqRangeSlider.min.js") %>" type="text/javascript"></script> <script src="<% = ResolveUrl("~/Scripts/jquery.jqChart.min.js") %>" type="text/javascript"></script> <!--[if IE]><script lang="javascript" type="text/javascript" src="<% = ResolveUrl("~/Scripts/excanvas.js") %>"></script><![endif]--> </head> <body> <form id="form1" runat="server"> <asp:ObjectDataSource ID="ObjectDataSource1" runat="server" SelectMethod="GetData" TypeName="SamplesBrowser.Models.ChartData"></asp:ObjectDataSource> <jqChart:Chart ID="Chart1" Width="500px" Height="300px" runat="server" DataSourceID="ObjectDataSource1"> <Title Text="Chart Title"></Title> <Animation Enabled="True" Duration="00:00:01" /> <Axes> <jqChart:CategoryAxis Location="Bottom" ZoomEnabled="true"> </jqChart:CategoryAxis> </Axes> <Series> <jqChart:ColumnSeries XValuesField="Label" YValuesField="Value1" Title="Column"> </jqChart:ColumnSeries> <jqChart:LineSeries XValuesField="Label" YValuesField="Value2" Title="Line"> </jqChart:LineSeries> </Series> </jqChart:Chart> </form> </body> </html>   Official Site | Samples | Download | Documentation | Forum | Twitter

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  • How to transform mesh components?

    - by Lea Hayes
    I am attempting to transform the components of a mesh directly using a 4x4 matrix. This is working for the vertex positions, but it is not working for the normals (and probably not the tangents either). Here is what I have: // Transform vertex positions - Works like a charm! vertices = mesh.vertices; for (int i = 0; i < vertices.Length; ++i) vertices[i] = transform.MultiplyPoint(vertices[i]); // Does not work, lighting is messed up on mesh normals = mesh.normals; for (int i = 0; i < normals.Length; ++i) normals[i] = transform.MultiplyVector(normals[i]); Note: The input matrix converts from local to world space and is needed to combine multiple meshes together.

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  • How can I enable auto-switching HDMI sound on Ubuntu 12.04?

    - by João Ciocca
    I've just installed Ubuntu 12.04 on my Lenovo G550 notebook and decided to test the main thing I use it for, on Windows: watching movies and series on my living room TV. Plugged in the HDMI cable, screen auto-configured nicely - awesome. But the sound is coming through my notebook's speakers, instead of my TV. Searched for almost an hour on Google, found a couple of things - nothing that helped, though. Here are two links that made me sad: Another question on AskUbuntu "a better sounding world" post about HDMI On 2, David says that autoswitching was disabled... so how can I enable it?

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  • New insights I can learn from the Groovy language

    - by Andrea
    I realize that, for a programmer coming from the Java world, Groovy contains a lot of new ideas and cool tricks. My situation is different, as I am learning Groovy coming from a dynamic background, mainly Python and Javascript. When learning a new language, I find that it helps me if I know beforehand which features are more or less old acquaintances under a new syntax and which ones are really new, so that I can concentrate on the latter. So I would like to know which traits distinguish Groovy among the dynamic languages. What are the ideas and insights that a programmer well-versed in dynamic languages should pay attention to when learning Groovy?

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  • Why everybody should do Sales!

    - by FelixWehmeyer
    I speak with many business students and ask them what job they want to get into. Most of them tell me they want a job in Marketing, Management Consulting or Finance. I hardly ever hear “Sales, that is what I want to do”, and I often wonder why. I would like to start with a quote from Zig Ziglar, a successful salesman: "Nothing happens until someone sells something." But to get back to the main point, why wouldn’t you want to get in sales? When people think of sales, they picture a typical salesman in their head and think that selling is scary and all about manipulating, pressuring and pushing someone into buying something they don’t need. Are these stereotypes accurate? I don’t believe so: So why should you want to be in sales? If you think about selling as providing the solution for the problem and talking about the benefits of making a decision, then every job in this world comes out of selling. In every job you deal with coworkers that you want to convince of your ideas or convincing your boss that the project you want to work on is good for the company.  These days, consumers and businesses are very well informed about services and products. When we are talking about highly complex products, such as IT solutions, businesses don’t accept your run-of-the-mill salesman who is pushing a sale. These are often long projects where salespeople have a consulting and leading role. Salespeople need to be able to consult companies and customers with their problem and convince a client that their solution is the best fit. Next to the fact that sales, is by far, not as scary and shady as you thought, there are a few points that will make you want to consider a sales career: Negotiating skills – When you are in sales you will learn how to negotiate. Salespeople learn to listen to their customers and try to make them happy, overcoming objections and come to a final agreement that both parties are happy with. Persistence/Challenge – As a salesperson you will often hear a negative answer, in a sales role you will start to embrace this and see a ‘no’ as a challenge not as a rejection. This attitude change can help you a lot in your career, but also in your personal life. You will become more optimistic and gain a go-getter attitude. Salary – As salespeople are seen as the moneymakers for the company, companies often reward their sales teams generously. Most likely in a sales role, you will receive a good basic salary and often you get nice bonuses on top of that based on your performance. Oracle is, for instance, the company that offers the highest average commission in the world. Further you can expect many other benefits as companies know that there is a high demand for good salespeople. Teamwork – Sales is a lot like having your own business, you are responsible for your own territory or set of clients. You are the one who is responsible for the revenue coming from that territory. So in order to gain revenue you will have to work together with many departments and people to make that happen. Every (potential) client could be seen as a different project, and you are the project leader. Understanding customers and the business – From any job that you choose sales will get you the most insight in the market. Salespeople are usually well-connected, talk with different customers and learn about the market and are up-to-date about all latest changes. Even if you want to change to a different role in the long run, you have a great head start as you understand the market and customers like no one else. Job security – Look at all the job postings out there. Many of them are sales-related. So if you want to have a steady job, plenty of choice and companies willing to invest in you, sales could be something for you.  Are you interested in exploring a sales career? At Oracle we are always looking for good sales professionals and fresh graduates who want to get into sales! For many languages such as Flemish, Dutch, German, French, Swedish and Norwegian (and more) we are currently looking for graduates who want to develop their career in Oracle. Please have a look at this article for the experience of a Business Development Consultant at Oracle in Dublin. Want to learn more about this job check out this link or send an email to jessica.ebbelaar-at-oracle.com! Have a look at our website http://campus.oracle.com for all of our other latest sales and non-sales vacancies!

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  • Using Resources the Right Way

    - by BuckWoody
    It’s an interesting time in computing technology. At one point there was a dearth of information available for solving a given problem, or educating ourselves on broader topics so that we can solve problems in the future. With dozens, perhaps hundreds or thousands of web sites and content available (for free, in many cases) from vendors, peers, even colleges and universities, it seems like there is actually too much information. Who has the time to absorb all this information and training? Even if you had the inclination, where to start? In fact, it seems so overwhelming that I often hear people saying that they can’t find the training they need, or that vendor X or Y “doesn’t help their users”. On questioning these folks, however, I often find that they – and sometimes I - haven’t put in the effort to learn what resources we have. That’s where blogs, like this one, can help. If you follow a blog, either by checking it often or perhaps subscribing to the Really Simple Syndication (RSS) feed, you’ll be able to spread out the search or create a mental filter for the information you need. But it’s not enough just read a blog or a web page. The creators need real feedback – what doesn’t work, and what does. Yes, you’re allowed to tell a vendor or writer “This helped me because…” so that you reinforce the positives. To be sure, bring up what doesn’t work as well –  that’s fine. But be specific, and be constructive. You’d be surprised at how much it matters. I know for a fact at Microsoft we listen – there is a real live person that reads your comments. I’m sure this is true of other vendors, and I also know that most blog authors – yours truly most especially – wants to know what you think.   In this blog entry I’d to call your attention to three resources you have at your disposal, and how you can use them to help. I’ll try to bring up things like this from time to time that I find useful, and cover in them in more depth like this. Think of this as a synopsis of a longer set of resources that you can use to filter whether you want to research further, bookmark, or forward on to a circle of friends where you think it might help them.   Data Driven Design Concepts http://msdn.microsoft.com/en-us/library/windowsazure/jj156154 I’ll start with a great site that walks you through the process of designing a solution from a data-first perspective. As you know, I believe all computing is merely re-arranging data. If you follow that logic as well, you’ll realize that whenever you create a solution, you should start at the data-end of the application. This resource helps you do that. Even if you don’t use the specific technologies the instructions use, the concepts hold for almost any other technology that deals with data. This should be a definite bookmark for a developer, DBA, or Data Architect. When I mentioned my admiration for this resource here at Microsoft, the team that created it contacted me and asked if I’d share an e-mail address to my readers so that you can comment on it. You’re guaranteed to be heard – you can suggest changes, talk about how useful – or not – it is, and so on. Here’s that address:  [email protected]   End-to-End Example of a complete Hybrid Application – with Live Demo https://azurestocktrader.cloudapp.net/Default.aspx I learn by example. I also like having ready-made, live, functional demos that show the completed solution at work. If you’ve ever wanted to learn how a complex, complete, hybrid application that bridges on-premises systems with cloud-based databases, code, functions and more, this is it. It’s a stock-trading simulator, and you can get everything from the design to the code itself, or you can just play with the application. It’s running on Windows Azure, the actual production servers we use for everything else. Using a Cloud-Based Service https://azureconfigweb.cloudapp.net/Default.aspx Along with that stock-trading application, you have a full demonstration and usable code sample of a web-based service available. If you’re a developer, this is a style of code you need to understand for everything from iPhone development to a full Service-Oriented Architecture (SOA) environment. So check out these resources. I’ll post more from time to time as I run across them. Hopefully they’ll be as useful to you as they are to me. Oh, and if you have a comment on any of the resources, let them know. And if you have any comments about these or any of my entries, feel free to post away. To quote a famous TV Show: “Hello Seattle – I’m listening…”

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  • Online ALTER TABLE in MySQL 5.6

    - by Marko Mäkelä
    This is the low-level view of data dictionary language (DDL) operations in the InnoDB storage engine in MySQL 5.6. John Russell gave a more high-level view in his blog post April 2012 Labs Release – Online DDL Improvements. MySQL before the InnoDB Plugin Traditionally, the MySQL storage engine interface has taken a minimalistic approach to data definition language. The only natively supported operations were CREATE TABLE, DROP TABLE and RENAME TABLE. Consider the following example: CREATE TABLE t(a INT); INSERT INTO t VALUES (1),(2),(3); CREATE INDEX a ON t(a); DROP TABLE t; The CREATE INDEX statement would be executed roughly as follows: CREATE TABLE temp(a INT, INDEX(a)); INSERT INTO temp SELECT * FROM t; RENAME TABLE t TO temp2; RENAME TABLE temp TO t; DROP TABLE temp2; You could imagine that the database could crash when copying all rows from the original table to the new one. For example, it could run out of file space. Then, on restart, InnoDB would roll back the huge INSERT transaction. To fix things a little, a hack was added to ha_innobase::write_row for committing the transaction every 10,000 rows. Still, it was frustrating that even a simple DROP INDEX would make the table unavailable for modifications for a long time. Fast Index Creation in the InnoDB Plugin of MySQL 5.1 MySQL 5.1 introduced a new interface for CREATE INDEX and DROP INDEX. The old table-copying approach can still be forced by SET old_alter_table=0. This interface is used in MySQL 5.5 and in the InnoDB Plugin for MySQL 5.1. Apart from the ability to do a quick DROP INDEX, the main advantage is that InnoDB will execute a merge-sort algorithm before inserting the index records into each index that is being created. This should speed up the insert into the secondary index B-trees and potentially result in a better B-tree fill factor. The 5.1 ALTER TABLE interface was not perfect. For example, DROP FOREIGN KEY still invoked the table copy. Renaming columns could conflict with InnoDB foreign key constraints. Combining ADD KEY and DROP KEY in ALTER TABLE was problematic and not atomic inside the storage engine. The ALTER TABLE interface in MySQL 5.6 The ALTER TABLE storage engine interface was completely rewritten in MySQL 5.6. Instead of introducing a method call for every conceivable operation, MySQL 5.6 introduced a handful of methods, and data structures that keep track of the requested changes. In MySQL 5.6, online ALTER TABLE operation can be requested by specifying LOCK=NONE. Also LOCK=SHARED and LOCK=EXCLUSIVE are available. The old-style table copying can be requested by ALGORITHM=COPY. That one will require at least LOCK=SHARED. From the InnoDB point of view, anything that is possible with LOCK=EXCLUSIVE is also possible with LOCK=SHARED. Most ALGORITHM=INPLACE operations inside InnoDB can be executed online (LOCK=NONE). InnoDB will always require an exclusive table lock in two phases of the operation. The execution phases are tied to a number of methods: handler::check_if_supported_inplace_alter Checks if the storage engine can perform all requested operations, and if so, what kind of locking is needed. handler::prepare_inplace_alter_table InnoDB uses this method to set up the data dictionary cache for upcoming CREATE INDEX operation. We need stubs for the new indexes, so that we can keep track of changes to the table during online index creation. Also, crash recovery would drop any indexes that were incomplete at the time of the crash. handler::inplace_alter_table In InnoDB, this method is used for creating secondary indexes or for rebuilding the table. This is the ‘main’ phase that can be executed online (with concurrent writes to the table). handler::commit_inplace_alter_table This is where the operation is committed or rolled back. Here, InnoDB would drop any indexes, rename any columns, drop or add foreign keys, and finalize a table rebuild or index creation. It would also discard any logs that were set up for online index creation or table rebuild. The prepare and commit phases require an exclusive lock, blocking all access to the table. If MySQL times out while upgrading the table meta-data lock for the commit phase, it will roll back the ALTER TABLE operation. In MySQL 5.6, data definition language operations are still not fully atomic, because the data dictionary is split. Part of it is inside InnoDB data dictionary tables. Part of the information is only available in the *.frm file, which is not covered by any crash recovery log. But, there is a single commit phase inside the storage engine. Online Secondary Index Creation It may occur that an index needs to be created on a new column to speed up queries. But, it may be unacceptable to block modifications on the table while creating the index. It turns out that it is conceptually not so hard to support online index creation. All we need is some more execution phases: Set up a stub for the index, for logging changes. Scan the table for index records. Sort the index records. Bulk load the index records. Apply the logged changes. Replace the stub with the actual index. Threads that modify the table will log the operations to the logs of each index that is being created. Errors, such as log overflow or uniqueness violations, will only be flagged by the ALTER TABLE thread. The log is conceptually similar to the InnoDB change buffer. The bulk load of index records will bypass record locking. We still generate redo log for writing the index pages. It would suffice to log page allocations only, and to flush the index pages from the buffer pool to the file system upon completion. Native ALTER TABLE Starting with MySQL 5.6, InnoDB supports most ALTER TABLE operations natively. The notable exceptions are changes to the column type, ADD FOREIGN KEY except when foreign_key_checks=0, and changes to tables that contain FULLTEXT indexes. The keyword ALGORITHM=INPLACE is somewhat misleading, because certain operations cannot be performed in-place. For example, changing the ROW_FORMAT of a table requires a rebuild. Online operation (LOCK=NONE) is not allowed in the following cases: when adding an AUTO_INCREMENT column, when the table contains FULLTEXT indexes or a hidden FTS_DOC_ID column, or when there are FOREIGN KEY constraints referring to the table, with ON…CASCADE or ON…SET NULL option. The FOREIGN KEY limitations are needed, because MySQL does not acquire meta-data locks on the child or parent tables when executing SQL statements. Theoretically, InnoDB could support operations like ADD COLUMN and DROP COLUMN in-place, by lazily converting the table to a newer format. This would require that the data dictionary keep multiple versions of the table definition. For simplicity, we will copy the entire table, even for DROP COLUMN. The bulk copying of the table will bypass record locking and undo logging. For facilitating online operation, a temporary log will be associated with the clustered index of table. Threads that modify the table will also write the changes to the log. When altering the table, we skip all records that have been marked for deletion. In this way, we can simply discard any undo log records that were not yet purged from the original table. Off-page columns, or BLOBs, are an important consideration. We suspend the purge of delete-marked records if it would free any off-page columns from the old table. This is because the BLOBs can be needed when applying changes from the log. We have special logging for handling the ROLLBACK of an INSERT that inserted new off-page columns. This is because the columns will be freed at rollback.

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