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  • how to store data with many categories and many properties efficiently?

    - by Mickey Shine
    We have a large number of data in many categories with many properties, e.g. category 1: Book properties: BookID, BookName, BookType, BookAuthor, BookPrice category 2: Fruit properties: FruitID, FruitName, FruitShape, FruitColor, FruitPrice We have many categories like book and fruit. Obviously we can create many tables for them (MySQL e.g.), and each category a table. But this will have to create too many tables and we have to write many "adapters" to unify manipulating data. The difficulties are: 1) Every category has different properties and this results in a different data structure. 2) The properties of every categoriy may have to be changed at anytime. 3) Hard to manipulate data if each category a table (too many tables) How do you store such kind of data?

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  • How to write this in better way?

    - by dario
    Hi all. Let's look at this code: IList<IHouseAnnouncement> list = new List<IHouseAnnouncement>(); var table = adapter.GetData(); //get data from repository object -> DataTable if (table.Rows.Count >= 1) { for (int i = 0; i < table.Rows.Count-1; i++) { var anno = new HouseAnnouncement(); anno.Area = float.Parse(table.Rows[i][table.powierzchniaColumn].ToString()); anno.City = table.Rows[i][table.miastoColumn].ToString(); list.Add(anno); } } return list; Is it better way to write this in less code and better fashion (must be :-) )? Maybe using labda (but let mi know how)? Thanks in advance!

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  • Do null SQLite Data fields take up extra memory?

    - by CSharperWithJava
    I'm using the built in sqlite library on the Android platform. I'm considering adding several general purpose fields that users will be able to use for their own custom applications, but these fields will be blank most of the time. My question is, how much overhead will these blank fields add to my database? Do null fields even take up per record memory in sqlite? If so, how much? I don't quite understand the inner workings of a sqlite database.

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  • db optimization - have a total field or query table?

    - by Dorian Fife
    I have an app where users get points for actions they perform - either 1 point for an easy action or 2 for a difficult one. I wish to display to the user the total number of points he got in my app and the points obtained this week (since Monday at midnight). I have a table that records all actions, along with their time and number of points. I have two alternatives and I'm not sure which is better: Every time the user sees the report perform a query and sum the points the user got Add two fields to each user that records the number of points obtained so far (total and weekly). The weekly points value will be set to 0 every Monday at midnight. The first option is easier, but I'm afraid that as I'll get many users and actions queries will take a long time. The second option bares the risk of inconsistency between the table of actions and the summary values. I'm very interested in what you think is the best alternative here. Thanks, Dorian

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  • Organizing development teams

    - by Patrick
    A long time ago, when my company was much smaller, dividing the development work over teams was quite easy: the 'application' team developed the applications-specific logic, often requiring a deep insight of specific industry problems) the 'generic' team developed the parts that were common/generic for all applications (user interface related stuff, database access, low-level Windows stuff, ...) Over the years the boundaries between the teams have become fuzzy: the 'application' teams often write application-specific functionality with a 'generic' part, so instead of asking the 'generic' team to write that part for them, they write it themselves to speed up the developments; then donate it to the 'generic' team the 'generic' team's focus seems to be more 'maintenance oriented'. All of the 'very generic' code has already been written, so no new developments are needed in it, but instead they continuously have to support all the functionality donated by the application teams. All this seems to indicate that it's not a good idea anymore to have this split in teams. Maybe the 'generic' team should evolve into a 'software quality' team (defining and guarding the rules for writing good quality software), or into a 'software deployment' team (defining how software should be deployed, installed, ...). How do you split up the work in different teams if you have different applications? everybody can write generic code and donates it to a central 'generic' team? everybody can write generic code, but nobody 'manages' this generic code (everybody is the owner) generic code is written by a 'generic' team only and the applications have to wait until the 'generic' team delivers the generic part (via a library, via a DLL) there is no overlap in code between the different applications some other way? Notice that thee advantage of having the mix (allowing everybody to write everywhere in the code) is that: code is written in a more flexible way it's easier to debug the code since you can easily step into the 'generic' code in the debugger But the big (and maybe only) disadvantage is that this generic code may become nobody's responsibility if there is no clear team that manages it anymore. What is your vision?

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  • Which database should I use for best performance

    - by _simon_
    Hello, I am working in Visual Studio 2005, .NET 2.0. I need to write an application, which listens on COM port and saves incoming data to a database. Main feature: save incoming data (series of 13-digits numbers), if this number allready exists, then mark it as double. For example, there could be these records in database: 0000000000001 OK 0000000000002 OK 0000000000002 Double 0000000000003 OK 0000000000004 OK I could use SQL database, but I don't know if it is fast enough... Database should be able to store up to 10.000.000 records and write up to 100 records per minute (so it needs to check 100 times per minute if this record allready exists). Which database should I use? Maybe the whole database would need to be in RAM. Where could I learn more about this? Thanks

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  • DDD: Where to create entity objects?

    - by ciscoheat
    I have three entities that must interact: User, SupportTicketand PhoneConversation. When someone calls in requesting help, the User should have a SupportTicket assigned to him, with a PhoneConversation assigned to the Ticked describing the call. My question is: In what entity should I put the method CreatePhoneSupportTicket() that creates a new SupportTicket and a PhoneConversation, relates them to each other and finally relates the SupportTicket to the User? I'm guessing it can't be on the user because that would violate the SRP (the user does a few more things). But the method itself does more than one thing, it should create both a SupportTicket and a PhoneConversation. Is this a situation when a Service is a better solution then putting methods on entities? Thanks for your help!

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  • incapsulation of a code inmatlab

    - by user531225
    my code is pathname=uigetdir; filename=uigetfile('*.txt','choose a file name.'); data=importdata(filename); element= (data.data(:,10)); in_array=element; pattern= [1 3]; locations = cell(1, numel(pattern)); for p = 1:(numel(pattern)) locations{p} = find(in_array == pattern(p)); end idx2 = []; for p = 1:numel(locations{1}) start_value = locations{1}(p); for q = 2:numel(locations) found = true; if (~any((start_value + q - 1) == locations{q})) found = false; break; end end if (found) idx2(end + 1) = locations{1}(p); end end [m2,n2]=size(idx2) res_name= {'one' 'two'}; res=[n n2]; In this code I finding a pattern in one of the column of my data file and counting how many times it's repeated. I have like 200 files that I want to do the same with them but unfotunatlly I'm stuck. this is what I have added so far pathname=uigetdir; files=dir('*.txt'); for k=1:length(files) filename=files(k).name; data(k)=importdata(files(k).name); element{k}=data(1,k).data(:,20); in_array=element;pattern= [1 3]; locations = cell(1, numel(pattern)); for p = 1:(numel(pattern)) locations{p} = find(in_array{k}== pattern(p)); end idx2{k} = []; how can I continue this code..??

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  • Applet networking patterns

    - by Kristoffersen
    Hi SO. I have an applet that connects to a server, it receives some commands and based on that it haves to draw (or move) different things. Which patterns should I use? I assume that the network connection and applet should run in two different threads? Thanks, Kristoffer

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  • What are provenly scalable data persistence solutions for consumer profiles?

    - by Hubbard
    Consumer profiles with analytical scores [ConsumerID, 1..n demographical variables, 1...n analytical scores e.g. "likely to churn" "likely to buy an item 100$ in worth" etc.] have to be possible to query fast if they are to be used in customizing web-sites, consumer communications etc. Well. If you have: Large number of consumers Large profiles with a huge set of variables (as profiles describing human behaviour are likely to be..) ...you are in trouble. If you really have a physical relational database to which you target a query and then a physical disk starts to rotate someplace to give you an individual profile or a set of profiles, the profile user (a web site customizing a page, a recommendation engine making a recommendation..) has died of boredom before getting any observable results. There is the possibility of having the profiles in memory, which would of course increase the performance hugely. What are the most proven solutions for a fast-response, scalable consumer profile storage? Is there a shootout of these someplace?

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  • Tags php improving database speed and user experience

    - by Doodle
    How did stackOverFlow, excuse me if it wasn't the first implementation of this system. Decide what its initial tags where? I want to provide users with the best experience on my site and am implementing a tags system. I don't care about search engines or any of that. I just care about my users. Does any one have any advice about things that have failed or succeeded when they allowed users to tag things? Does any one know some good resources about the methodologies of user tagging? Does any one know some good resources about implementing a tags system from a programming perspective, database structures, theories, etc ? I'll give my check to who ever I feel points me in the best direction on the subject.

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  • How important is it that models be consistent across project components?

    - by RonLugge
    I have a project with two components, a server-side component and a client-side component. For various reasons, the client-side device doesn't carry a fully copy of the database around. How important is it that my models have a 1:1 correlation between the two sides? And, to extend the question to my bigger concern, are there any time-bombs I'm going to run into down the line if they don't? I'm not talking about having different information on each side, but rather the way the information is encapsulated will vary. (Obviously, storage mechanisms will also vary) The server side will store each user, each review, each 'item' with seperate tables, and create links between them to gather data as necessary. The client side shouldn't have a complete user database, however, so rather than link against the user for gathering things like 'name', I'd store that on the review. In other words... --- Server Side --- Item: +id //Store stuff about the item User: +id +Name -Password Review: +id +itemId +rating +text +userId --- Device Side --- Item: +id +AverageRating Review: +id +rating +text +userId +name User: +id +Name //Stuff The basic idea is that certain 'critical' information gets moved one level 'up'. A user gets the list of 'items' relevant to their query, with certain review-orientation moved up (i. e. average rating). If they want more info, they query the detail view for the item, and the actual reviews get queried and added to the dataset (and displayed). If they query the actual review, the review gets queried and they pick up some additional user info along the way (maybe; I'm not sure if the user would have any use for any of the additional user information). My basic concern is that I don't wan't to glut the user's bandwidth or local storage with a huge variety of information that they just don't need, even if proper database normalizations suggests that information REALLY should be stored at a 'lower' level. I've phrased this as a fairly low-level conceptual issue because that's the level I'm trying to think / worry over, but if it matters I'm creating a PHP / MySQL server that provides data for a iOS / CoreData client.

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  • What considerations should be made when creating a reporting framework for a business?

    - by Andrew Dunaway
    It's a pretty classic problem. The company I work for has numerous business reports that are used to track sales, data feeds, and various other metrics. Of course this also means that there is a conglomerate of disparate frameworks, ASP.net pages, and areas where these reports can be found. There have been some attempts at consolidating these into a single entity, but nothing has stuck yet. Since this is a common problem, and I am sure solved innumerable times, I wanted to see what others have done. For the most part these can be boiled down to the following pieces: A SQL query against our database to gather data A presentation of data, generally in a data grid Filtering that can vary based on data types and the business needs Some way to organize the reports, a single drop down gets long and unmanageable quickly A method to download data to alter further, perhaps a csv file My first thought was to create a framework in Silverlight with Linq to Sql. Mainly just because I like it and want to play with it which probably is not the best reason. I also thought the controls grant a lot of functionality like sorting, dragging columns, etc. I was also curious about the printing in Silverlight 4. Which brings me around to my original question, what is the best way to do this? Is there a package out there I can just buy that will do it for me? The Silverlight approach seems pretty easy, after it's setup and templated, but maybe it's a bad idea and I can learn from someone else?

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  • Table in DB for generating primary keys?

    - by Sapphire
    Do you ever use a separate table for "generating" artificial primary keys for DB (and why)? What I mean is to have a table with two columns, table name and current ID - with which you could get new "ID" for some table by simply locking the row with that table name, getting the current value of the key, increment it by one, and unlock the row. Why would you prefer this over standard integer identity column? P.S. The "idea" is from Fowlers Patterns of Enterprise Application Architecture, btw...

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  • How to handle product ratings in a database

    - by Mel
    Hello, I would like to know what is the best approach to storing product ratings in a database. I have in mind the following two (simplified, and assuming a MySQL db) scenarios: Scenario 1: Create two columns in the product table to store number of votes and the sum of all votes. Use columns to get an average on the product display page: products(productedID, productName, voteCount, voteSum) Pros: I will only need to access one table, and thus execute one query to display product data and ratings. Cons: Write operations will be executed in a table whose original purpose is only to furnish product data. Scenario 2: Create an additional table to store ratings. products(productID, productName) ratings(productID, voteCount, voteSum) Pros: Isolate ratings into a separate table, leaving the products table to furnish data on available products. Cons: I will have to execute two separate queries on product page requests (one for data and another for ratings). In terms of performance, which of the following two approaches is best: Allow users to execute an occasional write query to a table that will handle hundreds of read requests? Execute two queries at every product page, but isolate the write query into a separate table. I'm a novice to database development, and often find myself struggling with simple questions such as these. Many thanks,

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  • 4GB limitation on these embedded/express DBs good enough? what's next if limitation is reached?

    - by edwin.nathaniel
    I'm wondering how long a (theoretically) desktop-app can consume the full 4GB limitation of these express/embedded database products (SQL-Server Express, Oracle Express, SQLite3, etc) provided that big blobs will be stored in filesystem. Also what would be your strategy when it hits the 4GB? Archive the old DB Copy 1-3 months of data to the new DB (consider this as cache strategy?) Start using the new DB from this point onward (How do you access the old data?) I understand that the answer might varies depending on how much data you stored in the table/column. But please describe based on your experience (what kind of desktop-app, write/read heavy, how long will it reach according to your guess).

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  • Game Objects Talking To Each Other

    - by PhilCK
    What is a good way of dealing with objects and having them talk to each other? Up until now all my games hobby/student have been small so this problem was generally solved in a rather ugly way, which lead to tight integration and circular dependencies. Which was fine for the size of projects I was doing. However my projects have been getting bigger in size and complexity and now I want to start re-using code, and making my head a simpler place. The main problem I have is generally along the lines of Player needs to know about the Map and so does the Enemy, this has usually descended into setting lots of pointers and having lots of dependencies, and this becomes a mess quickly. I have thought along the lines of a message style system. but I cant really see how this reduces the dependencies, as I would still be sending the pointers everywhere. Thanks. PS: I guess this has been discussed before, but I don't know what its called just the need I have.

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  • How to model file system operations with REST?

    - by massive
    There are obvious counterparts for some of file systems' basic operations (eg. ls and rm), but how would you implement not straightforwardly RESTful actions such as cp or mv? As answers to the question REST services - exposing non-data “actions” suggest, the preferred way of implementing cp would include GETting the resource, DELETing it and PUTting it back again with a new name. But what if I would need to do it efficiently? For instance, if the resource's size would be huge? How would I eliminate the superfluous transmission of resource's payload to client and back to the originating server? Here is an illustration. I have a resource: /videos/my_videos/2-gigabyte-video.avi and I want copy it into a new resource: /videos/johns_videos/copied-2-gigabyte-video.avi How would I implement the copy, move or other file system actions the RESTful way? Or is there even a proper way? Am I doing it all wrong?

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  • Sql Server Development Server and Live

    - by Chris
    I have a database project that goes through iterations (only one so far) and I need to deploy a testing version to a live server. I'm not sure how to go about this. I can make all the changes in a copy and then remake those changes in the live version. That doesn't make sense. Is there a way to change a server name to an existing server? What's the best practice for this scenario?

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