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• Is it necessary to create a database with as few tables as possible

  - by Shaheer

  Should we create a database structure with a minimum number of tables? Should it be designed in a way that everything stays in one place or is it okay to have more tables? Will it in anyway affect anything? I am asking this question because a friend of mine modified some database structure in mediaWiki. In the end, instead of 20 tables he was using only 8, and it took him 8 months to do that (it was his college assignment). EDIT I am concluding the answer as: size of the tables does NOT matter, until the case is exceptional; in which case the denormalization may help. Thanks to everyone for the answers.

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• Configuration data: single-row table vs. name-value-pair table

  - by Heinzi

  Let's say you write an application that can be configured by the user. For storing this "configuration data" into a database, two patterns are commonly used. The single-row table CompanyName | StartFullScreen | RefreshSeconds | ... ---------------+-------------------+------------------+-------- ACME Inc. | true | 20 | ... The name-value-pair table ConfigOption | Value -----------------+------------- CompanyName | ACME Inc. StartFullScreen | true (or 1, or Y, ...) RefreshSeconds | 20 ... | ... I've seen both options in the wild, and both have obvious advantages and disadvantages, for example: The single-row tables limits the number of configuration options you can have (since the number of columns in a row is usually limited). Every additional configuration option requires a DB schema change. In a name-value-pair table everything is "stringly typed" (you have to encode/decode your Boolean/Date/etc. parameters). (many more) Is there some consensus within the development community about which option is preferable?

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• Proper Data Structure for Commentable Comments

  - by Wesley

  Been struggling with this on an architectural level. I have an object which can be commented on, let's call it a Post. Every post has a unique ID. Now I want to comment on that Post, and I can use ID as a foreign key, and each PostComment has an ItemID field which correlates to the Post. Since each Post has a unique ID, it is very easy to assign "Top Level" comments. When I comment on a comment however, I feel like I now need a PostCommentComment, which attaches to the ID of the PostComment. Since ID's are assigned sequentially, I can no longer simply use ItemID to differentiate where in the tree the comment is assigned. I.E. both a Post and a Post Comment might have an ID of '5', so my foreign key relationship is invalid. This seems like it could go on infinitely, with PostCommentCommentComment's etc... What's the best way to solve this? Should I have a field in the comment called "IsPostComment" or something of the like to know which collection to attach the ID to? This strikes me as the best solution I've seen so far, but now I feel like I need to make recursive DataBase calls which start to get expensive. Meaning, I get a Post and get all PostComments where ItemID == Post.ID && where IsPostComment == true Then I take that as a collection, gather all the ID's of the PostComments, and do another search where ItemID == PostComment[all].ID && where IsPostComment == false, then repeat infinitely. This means I make a call for every layer, and if I'm calling 100 Posts, I might make 1000 DB calls to get 10 layers of comments each. What is the right way to do this?

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• Alchemy like game for the web, open source. Any ideas for element combinations?

  - by JohnDel

  I created a web game like the Android game Alchemy. It's open source and in the back-end you can create your own elements / your own game. I was wondering what elements - ideas would be good to implement as a prototype / demo? Some ideas are: Colors Programming languages Chemical Compounds Same as the original alchemy Evolution of biological organisms What do you think? Any specific combination ideas?

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• Adding a forum to an existing site

  - by Andrew Heath

  I've got a site with ~500 registered members, 300 of which are what you'd call "active". Site data is kept in a MySQL dbase. I'd like to add a myBB forum to the site, but this question applies to any forum really. What I very much want to avoid is requiring my users to register both on the site and on the forum because my userbase is not technically literate and this would confuse a lot of them. However the forum software has its own registration, login, cookie, and password management system which naturally are different from the site's mechanics. I envision the following possibilities: install myBB into the existing database and customize the login code to unify the two systems. This would probably mean changing the site's code to use the myBB system as that would likely be less painful to refactor and wouldn't hurt future myBB upgrade ability. install myBB into separate database and write a bridging script of some sort that auto-registers existing site users with the forum if they elect to participate. Also check new forum registrations against the site's username list to prevent newcomers from taking existing names. run them fully separate and force users to re-register (easiest for ME, but least desirable for them) I would like a suggested course of action from those who have trod this path before... Thank you.

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• Callback Contract in WCF

  Callback contracts are a very powerful concept that is easily implemented in WCF. Using this, it is very easy to achieve event-like behavior between a service and client (duplex operations).

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• What's wrong with JavaScript

  - by ts01

  There is a lot of buzz around Dart recently, often questioning Google motivations and utility of Dart as replacement for JavaScript. I was searching for rationale of creating Dart rather than investing more effort in ECMAScript. In well known leaked mail its author is saying that Javascript has historical baggage that cannot be solved without a clean break. But there is only one concrete example given (apart of performance concerns) of "fundamental language problems", which is an existence of a single Number primitive So, my questions are: How an existence of a single Number primitive can be a "fundamental problem"? Are there other known "fundamental problems" in JavaScript?

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• Should I comment Tables or Columns in my database?

  - by jako

  I like to comment my code with various information, and I think most people nowadays do so while writing some code. But when it comes to database tables or columns, I have never seen anyone setting some comments, and, to be honest, I don't even think of looking for comments there. So I am wondering if some people are commenting their DB strcuture here, and if I should bother commenting, for instance when I create a new column to an existing table?

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• NCurses, scrolling of multiline items, "current item" pointer and "selected items"

  - by mjf

  I am looking for hints/ideas for the best (most effective) way on how to scroll multi-line items as well as emphasizing of the "current item" and "selected items" such as: 1 FOO ITEM 1 Foo sub-item 2 Foo sub-item 3 Foo sub-item 2 BAR ITEM 1 Bar sub-item 3 BAZ ITEM 1 Baz sub-item 2 Baz sub-item 4 RAB ITEM 5 ZZZ ITEM 1 Zzz sub-item 2 Zzz sub-item 3 Zzz sub-item 4 Zzz sub-item using NCurses (some combination of windows, sub-windows, pads, copywin? Uff! In fact, the lines could exceed the stdscr's width so that possibility to scroll left/right would be also nice - pads?)... The whole items (including the sub-items) are supposed to be emphasized as full-width window/pad areas. The "current item" (including it's set of lines) should be emphasized (i.e. using A_BOLD), selected set of items of choice (including the set of lines for each the selected item) should be emphasized in another way (i.e. using A_REVERSE). What would you choose to cope with it the most effective NCurses way? (The less redrawals/refreshes the better and terminal is supposed to have the ability to change it's size - such as XTerm running under "floating window" management.) Thank you for your ideas (or perhaps some piece of code where something similar is already solved - I was not able to find anything helpful on the Internet. I mean I am not going to copy/paste foreign code but programming NCurses properly is still somehow difficult to me). P.S.: Would you suggest to "smooth-scroll" +1/-1 screen line or rather "jump-scroll" +lines/-lines of the items? (I personally prefer the latter one.) Sincerely, -- mjf

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• Will it hurt my website's SEO friendliness if I host a french targetted website at, let's say, godaddy.com?

  - by Suraj

  Hi guys, I have read that the server location is important for a website to be SEO friendly. I am planning to build a website from scratch which is targetted mainly to french audience (in france), but I am planning to host the web site at godaddy.com. My concern is will it hurt the website SEO friendliness? Or do you recommend me to host the website in france itself? I have also read that I need to have a static IP Address. If it's true, can anyone explain me for what reason? Can anyone suggest me some good web hosting companies, prefereable in france? Thanks in advance!

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• Designing a large database with multiple sources

  - by CatchingMonkey

  I have been tasked with redesigning, or at worst optimising the structure of a database for a data warehouse. Currently, the database has 4 other source databases (which is due to expand to X number of others), all of which have their own data structures, naming conventions etc. At the moment an overnight SSIS package pulls the data from the various source and then for each source coverts the data into a standardised, usable format. These tables are then appended to each other creating a 60m row, 40 column beast!. This table is then used in a variety of ways from an OLAP cube to a web front end. The structure has been in place for a very long time, and the work I have been able to prove the advantages of normalisation, and this is the way I would like to go. The problem for me is that the overnight process takes so long I don't then want to spend additional time normalising the last table into something usable. Can anyone offer any insight or ideas into the best way to restructure or optimise the database efficiently? Edit: All the databases are MS SQL Server 2008 R2 Thanks in advance CM

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• What are current Biggest Challenges faced by Ecommerce Applications ?

  - by Rachel

  I am in the process to start Product Development for E-commerce and Online Retail domain but before starting I would like to know what are the biggest challenges faced by current state of Art E-Commerce Application ? Also I have not experience building e-commerce products and so what things should I keep in mind before developing one ? Is there are books, articles, blogs outside which I should refer to gain some knowledge before starting out ? Update: What are you thoughts on the recommendation engines for ecommerce applications ? What challenges we have with current state of recommendations engines for ecommerce web application and how can we overcome them ?

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• Architecture for Social Graph data that has a Time Frame Associated?

  - by Jay Stevens

  I am adding some "social" type features to an existing application. There are a limited # of node & edge types. Overall the data itself is relatively small (50,000 - 70,000 for each type of node) there will be a number of edges (relationships) between them (almost all directional). This, I know, is relatively easy to represent with an SDF store (such as BrightstarDB) or something like Microsoft's Trinity (or really many of the noSQL options). The thing that, I think, makes this a unique use case is that each relationship will have a timeframe associated with it (start and end dates). Right now, I'm thinking of just storing this in a relational structure and dealing with the headaches of "traversing the graph", but I'm looking for suggestions on a better approach (both in terms of data structure and server): Column ================ From_Node_ID Relationship To_Node_ID StartDate EndDate Any suggestions or thoughts are welcomed.

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• Using XML as data storage

  - by Kian Mayne

  I was thinking about the XML format and the following quote: “XML is not a database. It was never meant to be a database. It is never going to be a database. Relational databases are proven technology with more than 20 years of implementation experience. They are solid, stable, useful products. They are not going away. XML is a very useful technology for moving data between different databases or between databases and other programs. However, it is not itself a database. Don't use it like one.“ -Effective XML: 50 Specific Ways to Improve Your XML by Elliotte Rusty Harold (page 230, Part 4, Item 41, 2nd paragraph) This seems to really stress that XML should not be used for data storage and should only be used for program to program interoperability. Personally, I disagree and .NET's app.config file that's used to store a program's settings is an example of data storage in an XML file. However for databases rather than configurations etc XML should not be used. To develop my point, I will use two examples: A) Data about customers with fields that are all on one level i.e. there are a number of fields all relating to one customer with no children B) Data about configuration of an application where nested fields and properties make a lot of sense So my question is, Is this still a valid statement and is it now acceptable to store data using XML? EDIT: I've sent an email to the author of that quote to ask for his input/extra context.

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• How to refactor a Python “god class”?

  - by Zearin

  Problem I’m working on a Python project whose main class is a bit “God Object”. There are so friggin’ many attributes and methods! I want to refactor the class. So Far… For the first step, I want to do something relatively simple; but when I tried the most straightforward approach, it broke some tests and existing examples. Basically, the class has a loooong list of attributes—but I can clearly look over them and think, “These 5 attributes are related…These 8 are also related…and then there’s the rest.” getattr I basically just wanted to group the related attributes into a dict-like helper class. I had a feeling __getattr__ would be ideal for the job. So I moved the attributes to a separate class, and, sure enough, __getattr__ worked its magic perfectly well… At first. But then I tried running one of the examples. The example subclass tries to set one of these attributes directly (at the class level). But since the attribute was no longer “physically located” in the parent class, I got an error saying that the attribute did not exist. @property I then read up about the @property decorator. But then I also read that it creates problems for subclasses that want to do self.x = blah when x is a property of the parent class. Desired Have all client code continue to work using self.whatever, even if the parent’s whatever property is not “physically located” in the class (or instance) itself. Group related attributes into dict-like containers. Reduce the extreme noisiness of the code in the main class. For example, I don’t simply want to change this: larry = 2 curly = 'abcd' moe = self.doh() Into this: larry = something_else('larry') curly = something_else('curly') moe = yet_another_thing.moe() …because that’s still noisy. Although that successfully makes a simply attribute into something that can manage the data, the original had 3 variables and the tweaked version still has 3 variables. However, I would be fine with something like this: stooges = Stooges() And if a lookup for self.larry fails, something would check stooges and see if larry is there. (But it must also work if a subclass tries to do larry = 'blah' at the class level.) Summary Want to replace related groups of attributes in a parent class with a single attribute that stores all the data elsewhere Want to work with existing client code that uses (e.g.) larry = 'blah' at the class level Want to continue to allow subclasses to extend, override, and modify these refactored attributes without knowing anything has changed Is this possible? Or am I barking up the wrong tree?

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• What are the downsides to using dependency injection?

  - by kerry

  I recently came across an interesting question on stack overflow with some interesting reponses.  I like this post for three reasons. First, I am a big fan of dependency injection, it forces you to decouple your code, create cohesive interfaces, and should result in testable classes. Second, the author took the approach I usually do when trying to evaluate a technique or technology; suspend personal feelings and try to find some compelling arguments against it. Third, it proved that it is very difficult to come up with a compelling argument against dependency injection. What are the downsides to using dependency injection?

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• Limit The Game Loop?

  - by user1758938

  How do I make a game go at the same speed? You probly dont understand that so here are examples: This Would Loop Too Fast while(true) { GetInput(); Render(); } This Just Wont Work, Hard To Exlplain while(true) { GetInput(); Render(); Sleep(16); } Basicly How Do I Sync It To Any FrameRate And Still Have To Input And Funtions Going At The Same Rate?

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• Can I use access used by Visual Basic for building a database [on hold]

  - by user3413537

  I am the only programmer where I work (summer job) and I am a student with only a few years of programming experience. So I was asked to build a database and I am very excited about this project because hopefully I can learn a lot from this. Using this database my manager is supposed to be able to assign work (dealing with businesses) to different people within the company using an interface (all workers have a shared drive). When workers are done with that paperwork related to the business, they can check off that its done, add comments at the bottom of the interface, and then move on to the next business. The only experience I've had with databases is some querying with SQL, and I've built GUI interfaces with JAVA. The information on the interface will be populated from Excel so workers know what businesses they are dealing with. I've done some research and I believe the best way to build this would be building a GUI using Microsoft Visual Studio (Visual Basic) first, then figuring out a way to populate the Interface from Excel. Also because the data is pretty straight forward and not complicated I will be using MS Access to store and track the database. I know this won't be easy, but for all you geniuses out there, is this on the right path? Thanks.

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• When to use abstract classes instead of interfaces and extension methods in C#?

  - by Gulshan

  "Abstract class" and "interface" are similar type of ideas, while interface being more abstract. One need of abstract classes was to provide method implementations for the derived classes. But in C#, that need has also been reduced by lately introduced extension methods. So, in C#, when should we use abstract classes instead of using interfaces and extension methods associated with the interface? And now, we can use 'Properties' in interfaces also. A notable example of interface+ extension methods is the Heavily used IEnumerable and it's helper methods. You use Linq and it's all by this extension methods!

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• Gathering all data in single iteration vs using functions for readable code

  - by user828584

  Say I have an array of runners with which I need to find the tallest runner, the fastest runner, and the lightest runner. It seems like the most readable solution would be: runners = getRunners(); tallestRunner = getTallestRunner(runners); fastestRunner = getFastestRunner(runners); lightestRunner = getLightestRunner(runners); ..where each function iterates over the runners and keeps track of the largest height, greatest speed, and lowest weight. Iterating over the array three times, however, doesn't seem like a very good idea. It would instead be better to do: int greatestHeght, greatestSpeed, leastWeight; Runner tallestRunner, fastestRunner, lightestRunner; for(runner in runners){ if(runner.height > greatestHeight) { greatestHeight = runner.height; tallestRunner = runner; } if(runner.speed > ... } While this isn't too unreadable, it can get messy when there is more logic for each piece of information being extracted in the iteration. What's the middle ground here? How can I use only a single iteration while still keeping the code divided into logical units?

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• Database Schema Usage

  - by CrazyHorse

  I have a question regarding the appropriate use of SQL Server database schemas and was hoping that some database gurus might be able to offer some guidance around best practice. Just to give a bit of background, my team has recently shrunk to 2 people and we have just been merged with another 6 person team. My team had set up a SQL Server environment running off a desktop backing up to another desktop (and nightly to the network), whilst the new team has a formal SQL Server environment, running on a dedicated server, with backups and maintenance all handled by a dedicated team. So far it's good news for my team. Now to the query. My team designed all our tables to belong to a 3-letter schema name (e.g. User = USR, General = GEN, Account = ACC) which broadly speaking relate to specific applications, although there is a lot of overlap. My new team has come from an Access background and have implemented their tables within dbo with a 3-letter perfix followed by "_tbl" so the examples above would be dbo.USR_tblTableName, dbo.GEN_tblTableName and dbo.ACC_tblTableName. Further to this, neither my old team nor my new team has gone live with their SQL Servers yet (we're both coincidentally migrating away from Access environments) and the new team have said they're willing to consider adopting our approach if we can explain how this would be beneficial. We are not anticipating handling table updates at schema level, as we will be using application-level logins. Also, with regards to the unwieldiness of the 7-character prefix, I'm not overly concerned myself as we're using LINQ almost exclusively so the tables can simply be renamed in the DMBL (although I know that presents some challenges when we update the DBML). So therefore, given that both teams need to be aligned with one another, can anyone offer any convincing arguments either way?

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• Adventures in the Land of CloudDB/NoSQL/NoAcid

  - by KKline

  Cloud, Bunny, or CloudBunny? Last year, some of my friends from Quest Software attended Hadoop World in New York. In 2009, I never would've guessed that Quest would be there with products, community initiatives, as a major sponsor and with presenters? There were just under 1,000 attendees who weren’t the typical devheads and geekasaurs you'd normally see at very techie events like Code Camps, SQL Saturdays, Cloud Camps and or even other NoSQL events such as the Cassandra Summit. We're talkin' enterprise...(read more)

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• Working with data and meta data that are separated on different servers

  - by afuzzyllama

  While developing a product, I've come across a situation where my group wants to store meta data for data entry forms (questions, layout, etc) in a different database then the database where the collected data is stored. This is mostly for security because we want to be able to have our meta data public facing, while keeping collected data as secure as possible. I was thinking about writing a web service that provides the meta information that the data collection program could access. The only issue I see with this approach is the front end is going to have to match the meta data with the collected data, which would be more efficient as a join on the back end. Currently, this system is slated to run on .NET and MSSQL. I haven't played around with .NET libraries running in SQL, but I'm considering trying to create logic that would pull from the web service, convert the meta data into a table that SQL can join on, and return the combined data and meta data that way. Is this solution the wrong way to approach the problem? Is there a pattern or "industry standard" way of bringing together two datasets that don't live in the same database?

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• Beginning with first project on game development [closed]

  - by Tsvetan

  Today is the day I am going to start my first real game project. It will be a Universe simulator. Basically, you can build anything from tiny meteor to quazars and universes. It is going to be my project for an olympiad in IT in my country and I really want to make it perfect(at least a bronze medal). So, I would like to ask some questions about organization and development methodologies. Firstly, my plan is to make a time schedule. In it I would write my plans for the next month or two(because that is the time I have). With this exact plan I hope to make my organisation at its best. Of course, if I am doing sth faster than the schedule I would involve more features for the game and/or continue with the tempo I have. Also, for the organisation I would make a basic pseudocode(maybe) and just rewrite it so it is compilable. Like a basic skeleton of everything. The last is an idea I tought of in the moment, but if it is good I will use it. Secondly, for the development methodologies, obviously, I think of making object-oriented code and make everything perfect(a lot of testing, good code, documentation etc.). Also, I am going to make my own menu system(I read that OpenGL hasn't got very good one). Maybe I would implement it with an xml file, holding the info about position of buttons, text boxes, images and everything. Maybe I would do a specific CSS for it and so on. I think that is very good way of doing the menu system, because it makes the presentation layer separate of the logic. But, if there is a better way, I would do it the better way. For the logic, well, I don't have much to say. OO code, testing, debuging, good and fast algorithms and so on. Also, a good documentation must be written and this is the area I need to make some research in. I think that is for now. I hope I have been enough descriptive. If more questions come on my mind, I will ask them. Edit: I think of blogging every part of the project, or at least writing down everything in a file or something like that. My question is: Is my plan of how to do everything around the project good? And if not, what is necessary to be improved and what other things I can involve for making the project good.

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• What's the best practice for async APIs that return futures on Scala?

  - by Maurício Linhares

  I have started a project to write an async PostgreSQL driver on Scala and to be async, I need to accept callbacks and use futures, but then accepting a callback and a future makes the code cumbersome because you always have to send a callback even if it is useless. Here's a test: "insert a row in the database" in { withHandler { (handler, future) => future.get(5, TimeUnit.SECONDS) handler.sendQuery( this.create ){ query => }.get( 5, TimeUnit.SECONDS ) handler.sendQuery( this.insert ){ query => }.get( 5, TimeUnit.SECONDS ).rowsAffected === 1 } } Sending the empty callback is horrible but I couldn't find a way to make it optional or anything like that, so right now I don't have a lot of ideas on how this external API should look like. It could be something like: handler.sendQuery( this.create ).addListener { query => println(query) } But then again, I'm not sure how people are organizing API's in this regard. Providing examples in other projects would also be great.

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