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• Run Win7 Guest (raw disk) in Ubuntu (which was installed as Dual Boot on existing Win7)

  - by kingdango

  I installed Ubuntu 12.10 on top of Win 7 as a dual boot (awesome!). I'm hoping to use VirtualBox to run my original Win7 instance as a guest OS under Ubuntu. I found this existing question and followed the directions to no avail. I can get the VMDK file created but when I run it I just get a blank black screen with no additional information and Windows never loads. I see no HD activity or anything that would indicate it's loading. I used this command to create the VMDK file: VBoxManager internalcommands createrawvmdk -filename ~/.VirtualBox/Win7Native.vmdk -rawdisk /dev/sda3 It looks like everything was created correctly but I just get a blank screen when I run the VM. I do get this warning when I boot the VM: VirtualBox - Warning The virtual machine execution may run into and error condition as described below... The medium '/home/XXX/.VirtualBox/Win7Native.vmdk' has a logical size of 583GB but the file system the medium is located on can only handle up to 16GB in theory. We strongly recommend to put all your virtual disk images and the snapshot folder on a proper file system (e.g. etc3) with a sufficient size. ErrorId: Fat Partition Detected Severity: Warning How can I get this working?

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• Retrieving data from database. Retrieve only when needed or get everything?

  - by RHaguiuda

  I have a simple application to store Contacts. This application uses a simple relational database to store Contact information, like Name, Address and other data fields. While designing it, I question came to my mind: When designing programs that uses databases, should I retrieve all database records and store them in objects in my program, so I have a very fast performance or I should always gather data only when required? Of course, retrieving all data can only be done if it`s not too many, but do you use this approach when you make sure that the database will be small (< 300 records for example)? I have designed once a similar application that fetches data only when needed, but that was slow (using a Access database). Thanks for all help.

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• Is C# development effectively inseparable from the IDE you use?

  - by Ghopper21

  I'm a Python programmer learning C# who is trying to stop worrying and just love C# for what it is, rather than constantly comparing it back to Python. I'm really get caught up on one point: the lack of explicitness about where things are defined, as detailed in this Stack Overflow question. In short: in C#, using foo doesn't tell you what names from foo are being made available, which is analogous to from foo import * in Python -- a form that is discouraged within Python coding culture for being implicit rather than the more explicit approach of from foo import bar. I was rather struck by the Stack Overflow answers to this point from C# programmers, which was that in practice this lack of explicitness doesn't really matter because in your IDE (presumably Visual Studio) you can just hover over a name and be told by the system where the name is coming from. E.g.: Now, in theory I realise this means when you're looking with a text editor, you can't tell where the types come from in C#... but in practice, I don't find that to be a problem. How often are you actually looking at code and can't use Visual Studio? This is revelatory to me. Many Python programmers prefer a text editor approach to coding, using something like Sublime Text 2 or vim, where it's all about the code, plus command line tools and direct access and manipulation of folders and files. The idea of being dependent on an IDE to understand code at such a basic level seems anathema. It seems C# culture is radically different on this point. And I wonder if I just need to accept and embrace that as part of my learning of C#. Which leads me to my question here: is C# development effectively inseparable from the IDE you use?

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• Information about rendering, batches, the graphical card, performance etc. + XNA?

  - by Aidiakapi

  I know the title is a bit vague but it's hard to describe what I'm really looking for, but here goes. When it comes to CPU rendering, performance is mostly easy to estimate and straightforward, but when it comes to the GPU due to my lack of technical background information, I'm clueless. I'm using XNA so it'd be nice if theory could be related to that. So what I actually wanna know is, what happens when and where (CPU/GPU) when you do specific draw actions? What is a batch? What influence do effects, projections etc have? Is data persisted on the graphics card or is it transferred over every step? When there's talk about bandwidth, are you talking about a graphics card internal bandwidth, or the pipeline from CPU to GPU? Note: I'm not actually looking for information on how the drawing process happens, that's the GPU's business, I'm interested on all the overhead that precedes that. I'd like to understand what's going on when I do action X, to adapt my architectures and practices to that. Any articles (possibly with code examples), information, links, tutorials that give more insight in how to write better games are very much appreciated. Thanks :)

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• I know the big picture but can't put it in place

  - by Simbilim

  Hi, I'm interested in web development and by that I mean the bigger projects like facebook or twitter. I know the basics of java, css, php and mysql. I know there is a lot more out there. I read about it. But I don't know what the purpose is and how to put in place. Things like: Scribe, thrift, casandra, Unix/Linux, shell/perl/python scripting, PostgreSQL, MongoDB, non-relational NoSQL datastores, JVM, nginx I want to know why they need it, how they use it and what te purpose is. What I need is a book like technical background of facebook for dummies or so. Are there any books or websites that explain this from scratch? Thank you!

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• How much a programmer should read in order to keep himself updated? [closed]

  - by anything

  There are lots of technical books available. Below are few links which lists some good books If you could only have one programming related book on your bookshelf what would it be and why? What non-programming books should a programmer read to help develop programming/thinking skills? Best books on the theory and practice of software architecture? http://stackoverflow.com/questions/1711/what-is-the-single-most-influential-book-every-programmer-should-read ... and the list can go on and on and on. It will be really difficult to read all of the above mentioned books. I am not sure if its even possible for anyone to do that. Even if you filter it based on one's area of interest or work, list is still very large. .. and the technology keeps on changing (even more books :-( ) So, my question is how much a programmer should read lets say per year? How much hours one should put in such activities to keep oneself up to date? How do we find out the time required? PS: Average programmer reads less than one book per year (Code complete). What about the good programmers?

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• Shoring up deficiencies in a "home grown" programmer?

  - by JohnP

  I started out by teaching myself BASIC on a Vic 20, and in college (mid 80's) I had Fortran, Pascal, limited C, machine and assembler (With a smattering of COBOL). I didn't touch programming from approx 1989 to 1999. At that point, I was lucky enough to get hired as a Clipper programmer. Took me about 6 months to learn most of it, and by now (13 yrs) I'm pretty expert in it. I have also picked up Cold Fusion, some C#, some ASP, SQL, etc. I know programming structures, but in most languages I'm missing the esoterics, and I know my code could be much tighter. The problem is that I've learned what I needed to, to get the job done. This results in a lot of gaps in practical knowledge. I am also missing out on a TON of theory. Things like SRP, Refactoring, etc are alien terms. (Although I grok the intent after a short read). In addition, I am in the position now of teaching junior programmers the company and our software, and I don't want to pass on the knowledge gaps. I know this is somewhat of a subjective question and may be closed, but how do you go back and pick up what you've missed?

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• Solution for distributing MANY simple network tasks?

  - by EmpireJones

  I would like to create some sort of a distributed setup for running a ton of small/simple REST web queries in a production environment. For each 5-10 related queries which are executed from a node, I will generate a very small amount of derived data, which will need to be stored in a standard relational database (such as PostgreSQL). What platforms are built for this type of problem set? The nature, data sizes, and quantities seem to contradict the mindset of Hadoop. There are also more grid based architectures such as Condor and Sun Grid Engine, which I have seen mentioned. I'm not sure if these platforms have any recovery from errors though (checking if a job succeeds). What I would really like is a FIFO type queue that I could add jobs to, with the end result of my database getting updated. Any suggestions on the best tool for the job?

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• Unique constraint on more than 10 columns

  - by tk

  I have a time-series simulation model which has more than 10 input variables. The number of distinct simulation instances would be more than 1 million, and each simulation instance generates a few output rows every day. To save the simulation result in a relational database, i designed tables like this. Table SimulationModel { simul_id : integer (primary key), input0 : string or numeric, input1 : string or numeric, ...} Table SimulationOutput { dt : DateTime (primary key), simul_id : integer (primary key), output0 : numeric, ...} My question is, is it fine to put an unique constraint on all of the input columns of SimulationModel table? If it is not a good idea, then what kind of other options do i have to make sure each model is unique?

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• Can anyone point me to some open source directX rendering engines or frameworks? [on hold]

  - by Jim

  I'm completely new to graphics API programmming, but not at all new to the theory and principle operation of game engines and rendering engines. That being said, I want to do some experiments of rendering very dense geometry scenes in a basic rendering engine or game engine. I don't need a lot of bells and whistles. What I need is enough control that I can implement my own scene graph algorithms and control the rendering pipeline very specifically. My ideal candidate engine would be either a rendering engine or game engine with a modular design that might be ready to go out of the box but would be simple enough in case I need to rip out some of the guts in the rendering management and implement my own. It's a tough call because I'm right at the level where it's almost better to go from scratch, but there's no sense in having to build every single basic thing such as heirarchical transforms, etc. I just want to work with rendering optimization to push dense geometry for maximum FPS. Does anyone have a suggestion for an engine or basic framework to use? I requested DirectX in my title because I figured it would likely be better supported and less likely for me to run into some obscure less-documented problem. But OpenGL might be acceptable if the recommended framework was definitely better than my other options. EDIT: I should add that I really want GPU tessellation support (part of adding to the density of geometry detail).

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• Cannot usermod -L in LightDM scripts

  - by user95723

  I'm running Xubuntu 12.04 and use the LightDM. I want to restrict access to the machine as a kind of parental control. This is how it should work I hook in a script that executes just before the greeter comes up. Within that script some awk processing will read an entry in a config file and will trigger a usermod -L or usermod -U depending on whether the user is allowed to login. While user is logged, a cron job will count down the entry in the config and forces a xfce4-session-logout if time is up. A cron job running on a server will upload the "credits" on a daily base. How is this idea? That's theory, now for the problems It appears for some unknown reason, the usermod command is not executed, neither as part of a display-setup-script nor within the greeter-setup-script. I wrote a small sandbox script usermod -L johndoe 2error.txt touch /etc/blabla 2error.txt The script is executing, cause the blabla file is existing. That means that the script must have been executed with root privileges. error.txt is empty but the usermod command has just no effect. Is this a bug or a feature. What's wrong? Best regards and thank you Oli

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• What open source document-oriented database system is most mature for Windows usage?

  - by jdk

  After using relational databases as back-end storage all my Windows programming life (currently .NET), I want to experiment with a document-oriented database by this Wikipedia definition; it can be standalone or layered over an existing non-commercial database system. What open source document-oriented database solution would you recommend from your own experience and why? A nice to have would be a .NET provider. Admittedly this is somewhat subjective and potentially argumentative so keep it real folks and I'll do the same - also your answers will be invaluable to others looking into document-oriented databases for the first time on Windows. I'm sure the overall value of your answers will outweigh any biases. Thanks.

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• Will I be able to get programming interviews at good software companies with a non-CS degree?

  - by friend

  I'll be graduating in a year, but I'll have a degree in Economics. I'm pretty much done with my Economics coursework, and by the time next year comes around I will have devoted 1.5 years to learning CS. I will have almost finished the requirements to graduate with a degree in CS, but unfortunately my school requires a science series that would add another 6-9 months of study if I were to try and get the degree (not to mention a max unit cap). I have or will have taken: Objected Oriented Programming Discrete Math Data structures Calculus through multivariable (doubt this matters at all) Linear Algebra (same) Computer Organization Operating Systems Computational Statistics (many data mining projects in R) Parallel Programming Programming Languages Databases Algorithms Compilers Artificial Intelligence I've done well in the ones I've taken, and I hope to do well in the rest, but will that matter if I can't say to the HR people that I have a CS degree? I'd be happy to get an internship at first too, so should I just apply as if I'm an intern and not looking for fulltime, and then try and parlay that into something? Sidenote if you have time -- Is a computer networks or theory of computation class important? Would it be worth taking either of those in lieu of a class on my list? edit -- I know this isn't AskReddit or College Confidential; I know there will be some outrage at posting a question like this. I'm merely looking for insight into a situation that I've been struggling with, and I think this is the absolute best place to find an answer to this question. Thanks.

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• Using Queries with Coherence Read-Through Caches

  - by jpurdy

  Applications that rely on partial caches of databases, and use read-through to maintain those caches, have some trade-offs if queries are required. Coherence does not support push-down queries, so queries will apply only to data that currently exists in the cache. This is technically consistent with "read committed" semantics, but the potential absence of data may make the results so unintuitive as to be useless for most use cases (depending on how much of the database is held in cache). Alternatively, the application itself may manually "push down" queries to the database, either retrieving results equivalent to querying the cache directly, or may query the database for a key set and read the values from the cache (relying on read-through to handle any missing values). Obviously, if the result set is too large, reading through the cache may cause significant thrashing. It's also worth pointing out that if the cache is asynchronously synchronized with the database (perhaps via database change listener), that an application may commit a transaction to the database, then generate a key set from the database via a query, then read cache entries through the cache, possibly resulting in a race condition where the application sees older data than it had previously committed. In theory this is not problematic but in practice it is very unintuitive. For this reason it often makes sense to invalidate the cache when updating the database, forcing the next read-through to update the cache.

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• How to structure opening hours of a place? May-be there's even an ontology for it?

  - by Ago

  Does anyone know any ontology which specifies opening hours of places? For example, I have a museum, which has 2 seasons. For low season (season start and end is specified), it is opened 10.00 - 18.00 on weekdays and 10-16 on saturday (on sunday it's closed), for high season it's opened 10-20 on weekdays and 10-18 on weekend. If there is no ontology, may-be people have experience, how best to structure information like that? I'm describing information in RDF. But whatever comments are welcome (even if you have relational database which holds given data). Thanks

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• Storing Data as XML BLOB

  - by NBrowne

  Hi, At the moment the team i am working with is looking into the possibility of storing data which is entered by users from a series of input wizard screens as an XML blob in the database. the main reason for this being that i would like to write the input wizard as a component which can be brought into a number of systems without having to bring with it a large table structure. To try to clarify if the wizard has 100 input fields (for example) then if i go with the normal relational db structure then their will be a 1 to 1 relationship so will have 100 columns in database. So to get this working in another system will have to bring the tables,strore procedures etc into the new system. I have a number of reservations about this but i would like peoples opinions?? thanks

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• How to better explain complex software process in software specs?

  - by Lostsoul

  I'm really struggling with my software specs. I am not a professional programmer but enjoy doing it for fun and made some software that I want to sell later but I'm not happy with the code quality. So I wanted to hire a real developer to rewrite my software in a more professional way so it will be maintainable by other developers in the future. I read and found some sample specs and made my own by applying their structure to my document and wanted to get my developer friend to read it and give me advice. After an hour and a half he understood exactly what I was trying to do and how I did it(my algorithms,stack,etc.). How can I get better at explaining things to developers? I add many details and explanations for everything(including working code) but I'm unsure the best way I can learn to pass detailed domain knowledge(my software applies big data, machine learning, graph theory to finance). My end goal is to get them to understand as much as possible from the document and then ask anything they do not understand, but right now it seems they need to extract alot of information from me. How can I get better at communicating domain knowledge to developers?

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• How to disguise a serverside mob as another?

  - by Shaun Wild

  I've been working a Minecraft sever mod and i want to be able to add a new entity to the server, but then make the server send the packets to the client, imitating another mob, for example.. Lets say say i have EntityPlayerNPC.class, what i want to do is have all of the packets that get sent to the client look like they are from that of another player which is on the player, therefore allowing me to add custom NPC's... Thinking about the theory i'm sure this can be done. I've tried looking around for where the packets are being sent from and whatnot, can anyone think up a solution? edit: i tried adding a new constructor to the Packet20NamedEntitySpawn class like so: public Packet20NamedEntitySpawn(String username, EntityLiving e){ this.entityId = 0; this.name = username; this.xPosition = MathHelper.floor_double(e.posX * 32.0D); this.yPosition = MathHelper.floor_double(e.posY * 32.0D); this.zPosition = MathHelper.floor_double(e.posZ * 32.0D); this.rotation = (byte)((int)(e.rotationYaw * 256.0F / 360.0F)); this.pitch = (byte)((int)(e.rotationPitch * 256.0F / 360.0F)); this.metadata = e.getDataWatcher(); } unfortunatley, that didn't work :(

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• How to return relationships in a custom un-typed dataservice provider

  - by monkey_p

  I have a custom .Net DataService and can't figure out how to return the data for relationships. The data base has 2 tables (Customer, Address). A Customer can have multiple addresses, but each address can only have on customer. I'm using Dictionary<string,object> as my data type. My question, for the following 2 urls how do i return the data. http://localhost/DataService/Customer(1)/Address http://localhost/DataService/Address(1)/Customer For the none relational queries I return a List<Dictionary<string,object>> So I imagined for the relation I should just populate the element with a either a Dictionary<string,object> for the single ones and a List<Dictionary<string,object>> for many relationships. But this just gives me a NullRefferenceException So what am I doing wrong?

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• ADO.NET DataService Exception

  - by Ravi

  Hi, I am working on C#.Net with ADO.NET Dataservice. I try to update one record to relational tabel, when I reach context.SetLink() I am getting exception("The context is not currently tracking the entity"). I don't know how to solve this problem. My code is specified below. LogNote dbLogNote =logNote; LogSubSession dbLogSubSession = (from p in context.LogSubSession where p.UID == logNote.SubSessionId select p).First<LogSubSession>() as LogSubSession; context.AddToLogNote(dbLogNote); dbLogNote.LogSubSession = dbLogSubSession; context.SetLink(dbLogNote, "LogSubSession", dbLogSubSession); context.SaveChanges(); Here LogSubSession is a primary table and LogNote is a foreign table. I am updating data into foreign table based on primary key table. Thanks

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• Provide A Scrolling "Camera" View Over A 2D Game Map

  - by BitCrash

  I'm in the process of attempting to create a 2D MMO type game with Kryonet and some basic sprites, mostly for my own learning. I have the back end set up great (By my standards) and I'm moving on to actually getting some things drawn onto the map. I cannot for the life of me figure out a solid way to have a "Camera" follow a player around a large area. The view pane for the game is 640 x 480 pixels, and each tile is 32x32 pixels (Thats 20 tiles wide and 15 high for the viewpane) I have tried a couple things to do this, but they did not seem to work out so well. I had a JScrollPane with 9 "Viewpane"-sized canvases in it, and tried to have the JScrollPane move in accordance with the player. The issue came when I reached the end of the JScrollPane. I tried to "Flip" canvases, sending the canvas currrently drawing the player to the middle of the 9 and load the corresponding maps onto the other ones. It was slow and worked poorly. I'm looking for any advice or previous experience with this; any ideas? Thank you! Edit and Clarification: I did not mean to mention Kryonet, I was merely providing peripheral information in case there was something that would help which I could not foresee. Instead of having an array of 9 canvases, why not just have one large canvas loading a large map every once in a while? I'm willing to have "load times" where as with the canvas array I would have none (in theory) to give the user a smooth experience. I could just change the size and location of the map with a modified setBounds() call on the canvas in a layered pane (layered because I have hidden swing items, like inventories and stuff) I'll try it out and post here how it goes for people asking the same question.

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• How do I take the advantage of the variable column key/value structure of Cassandra

  - by icejade

  If I have to predefine all the columns, how do I take the advantage of the variable column key/value structure of cassandra? If I use update table command, it will insert null for all the rows which don't have that column. This is same as relational DB. For example, for contact column family, I have name, phone, email. I have 100 contacts have all 3 field. Then number 101 contact has skype id which I want to add. If I use insert statement, it won't let me add skypeid since it's not defined in the CF. So I have to run alter statement to change the CF, then all the first 100 contacts will have a null field for each of them.

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• Understanding NoSQL Data Modeling - blog application

  - by Rushabh RajeshKumar Padalia

  I am creating an blogging application in Node.js + MongoDB Database. I have used relational Database like MySQL before but this is my first experience with NoSQL database. So I would like to conform my MongoDB data models before I move further. I have decided my blogDB to have 3 collections post_collection - stores information about that article comment_collection - store information about comments on articles user_info_collection - contains user inforamtion PostDB { _"id" : ObjectID(...), "author": "author_name", "Date": new Date(....), "tag" : ["politics" , "war"], "post_title": "My first Article", "post_content": "Big big article" "likes": 23 "access": "public" } CommentDB { "_id" : Objectid(...), "POST": "My First Article", "comment_by": "User_name", "comment": "MY comments" } UserInfoDB { "_id": ObjectID(...), "user": "User_name", "password": "My_password" } I would appreciate your comments.

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• Implementing Explosions

  - by Xkynar

  I want to add explosions to my 2D game, but im having a hard time with the architecture. Several game elements might be responsible for explosions, like, lets say, explosive barrels and bullets (and there might be chain reactions with close barrels). The only options i can come up with are: 1 - Having an array of explosions and treat them as a game element as important as any other Pros: Having a single array which is updated and drawn with all the other game element arrays makes it more organized and simple to update, and the explosive barrels at a first glance would be easy to create, simply by passing the explosion array as a pointer to each explosive barrel constructor Cons: It might be hard for the bullets to add an explosion to the vector, since bullets are shot by a Weapon class which is located in every mob, so lets say, if i create a new enemy and add it to the enemy array, that enemy will have a weapon and functions to be able to use it, and if i want the weapon (rocket launcher in this case) to have access to the explosions array to be able to add a new one, id have to pass the explosion array as a pointer to the enemy, which would then pass it to the weapon, which would pass it to the bullets (ugly chain). Another problem I can think of is a little more weird: If im checking the collisions between explosions and barrels (so i create a chain reaction) and i detect an explosion colliding with a barrel, if i add a new explosion while im iterating the explosions java will trow an exception. So this is kinda annoying, i cant iterate through the explosions and add a new explosion, i must do it in another way... The other way which isnt really well thought yet is to just add an explosive component to every element that might explode so that when it dies, it explodes or something, but i dont have good ways on implementing this theory either Honestly i dont like either the solutions so id like to know how is it usually done by actual game developers, sorry if my problem seems trivial and dumb.

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• Is there a tool that will show diagrams of my SQL database in real-time?

  - by Rising Star

  I've created some diagrams of SQL tables using the "Reverse Engineer" feature of Microsoft Office Visio. I like being able to visualize my relational databases in this manner. However, what I get is just a static document that I can print, e-mail to colleagues, and click widgets on. Earlier this year, I saw at a demo that the new version of Visual Studio 2010 has a new feature called the "Architect Explorer", which allows developers to view relationships among .net classes on the fly. It has many features for filtering the data that the developer is interested in. It would be really awesome if I could visually browse my tables and stored procedures and see what is related to what by primary key, foreign key, and referenced in stored procedures. I realize that I'm talking about two entirely different technologies and it's not a perfect analogy, but is there some similar tool that would allow me to visualize tables in my SQL database?

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