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  • Doctrine: How to traverse from an entity to another 'linked' entity?

    - by ropstah
    I'm loading 3 different tables using a cross-join in Doctrine_RawSql. This brings me back the following object: User -> User class (doctrine base class) Settings -> DoctrineCollection of Setting User_Settings -> DoctrineCollection of User_Setting The object above is the result of a many-to-many relationship between User and Setting where User_Setting acts as a reference table. User_Setting also contains another field named value. This obviously contains the value of the corresponding Setting. All good so far, however the Settings and User_Settings properties of the returned User object are in no way linked to each other (apart from the setting_id field ofcourse). Is there any direct way to traverse directly from the Settings property to the corresponding User_Settings property? This is the corresponding query: $sets = new Doctrine_RawSql(); $sets->select('{us.*}, {s.*}, {uset.*}') ->from('(User us CROSS JOIN Setting s) LEFT JOIN User_Setting uset ON us.user_id = uset.user_id AND s.setting_id = uset.setting_id') ->addComponent('us', 'User us') ->addComponent('uset', 'us.User_Setting uset') ->addComponent('s', 'us.Setting s') ->where('s.category_id = ? AND us.usr_auto_key = ?',array(1, 1)); $sets = $sets->execute();

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  • is this a design pattern?

    - by Michel
    Hi all, i have to build some financial data report, and for making the calculation, there are a lot of 'if then' situations: if it's a large client, subtract 10%, if it's postal code equals '10101', add 10%, if the day is on a saturday, make a difficult calculation etc. so i once read about this kind of example, and what they did was (hope i remember well) create a class with some base info and make it possible to add all kinds of calculationobjects to it. So to put what i remembered in pseudo code Basecalc bc = new baseCalc(); //put the info in the bc so other objects can do their if bc.Add(new Largecustomercalc()); bc.Add(new PostalcodeCalc()); bc.add(new WeekdayCalc()); the the bc would run the Calc() methods of all of the added Calc objects. As i type this i think all the Calc objects must be able to see the Basecalc properties to correctly perform their calculation logic. So all the if's are in the different Calc objects and not ALL in the Basecalc. does this make sense? I was wondering if this is some kind of design pattern?

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  • As an Agile Java developer, what should I be looking for when hiring a C++ developer?

    - by agoudzwaard
    I come from an effective team of Agile Java developers. We've had a lot of success in hiring more people like ourselves - people passionate about technology with experience primarily in the Agile Java/J2EE space. We're looking to hire our first C++ developer to serve as an on-shore resource for maintaining and adding to the C++ portion of our code base. Up until now the entirety of our C++ development has been done out of an off-shore location. We consider our interview process to be fairly thorough: A phone screen centered on Object-Oriented Programming and Java A non-trivial at-home code project using Java An in-person interview covering technical and behavioral competency We look for a demonstration of Agile best practices (expressive code, test-driven development, continuous integration) throughout the entire process, however there is a common conception that Agility is primarily practiced by Java developers. If we retrofit our interview process for C++, should we still expect Agile qualities when interviewing for a C++ role? I'm asking on behalf of a team that has worked with Java too long to know what a good C++ developer looks like. Specifically we're looking to answer the following questions: Can we expect a demonstrated understanding of OO design and Separation of Concerns? In the code project we want the candidate to write unit tests. Would a good C++ developer be surprised by this expectation? Are there any "extra" competencies we can look for? For example with Java developers we always look for a familiarity with Dependency Injection.

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  • Fluent NHibernate: Example of a one-to-many relationship on an abstract class of a table-per-subclas

    - by BigTommy79
    Hi All, I've been trying for ages to find an example (because I can't get it to work myself) of the correct mapping for a one-to-many relationship on an abstract class of a table-per-subclass implementation, in fluent nHibernate. An example below: I'm looking to map the list of Fines on the Debt abstract base class to the Fine class. if anyone knows of any tutorial or example they've come across before please let me know. Thanks, Tim public abstract class Entity { public int Id { get; set; } } public abstract class Debt : Entity { public decimal Balance { get; set; } public IList<Fine> Fines { get; set; } public Debt() { Fines = new List<Fine>(); } } public class CarLoan : Debt { } public class CreditCard : Debt { } public class LoanApplication : Entity { public IList<Debt> ExistingDebts { get; set; } public LoanApplication() { ExistingDebts = new List<Debt>(); } } public class Fine { public Int64 Cash { get; set; } }

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  • Rails 2.x provide meaningful error message with http basic authentication

    - by randombits
    I'm using basic http authentication in my rails app via the following code: class ApplicationController < ActionController::Base helper :all # include all helpers, all the time before_filter :authenticate private def authenticate authenticate_or_request_with_http_basic do |username, password| if username.nil? || password.nil? render :inline => %(xml.instruct! :xml, :version => "1.0", :encoding => "UTF-8" xml.errors do xml.error('Could not authenticate you.') end), :type => :builder, :status => 401 end end end end The problem is, if you do a curl http://127.0.0.1:3000/foo/1.xml without providing the -u username:password flag, you get a dead beat response like this: HTTP/1.1 401 Unauthorized Cache-Control: no-cache WWW-Authenticate: Basic realm="Foo" X-Runtime: 1 Content-Type: text/html; charset=utf-8 Content-Length: 27 Server: WEBrick/1.3.1 (Ruby/1.9.1/2010-01-10) Date: Thu, 03 Jun 2010 03:09:18 GMT Connection: Keep-Alive HTTP Basic: Access denied. Is it possible at all to render the inline XML I have above in the event a username and password is not provided by the user?

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  • Differences in accessing resources between Simulator and Device?

    - by Tony
    Is there some difference between the way that bundle resources can be accessed on the iPhone simulator versus a device (in my case, an iPad)? I am able to access a file on the former, but not the latter. NSString *filePath = [NSString stringWithFormat:@"%@%@",[[NSBundle mainBundle] bundlePath], @"/AppResources/html/pages/quickHelp.html"]; BOOL fileExists = [[NSFileManager defaultManager] fileExistsAtPath:filePath]; // fileExists == YES in the debugger on both the simulator and the device NSString *path = [NSString stringWithFormat:@"AppResources/html/pages/%@", contentsFileName]; NSString *pathForURL = [[NSBundle mainBundle] pathForResource:path ofType:@"html"]; NSURL *url = [NSURL fileURLWithPath:pathForURL isDirectory:NO]; The code above works fine in the simulator, but on the device pathForResource:path returns nil, so the last line throws a 'nil string parameter' exception. Am I missing something obvious? edit: Of course, in the above @"quickHelp" is being passed in the contentsFileName var. edit2: if it makes any difference, in my build settings "Base SDK" is set to "iPhone Device 4.0", and "iPhone OS Deployment Target" is set to "iPhone OS 3.1.3". Any other settings that might have an influence?

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  • Centralizing Messagebox handling for application

    - by DRapp
    I'm wondering how others deal with trying to centralize MessageBox function calling. Instead of having long text embedded all over the place in code, in the past (non .net language), I would put system and application base "messagebox" type of messages into a database file which would be "burned" into the executable, much like a resource file in .Net. When a prompting condition would arise, I would just do call something like MBAnswer = MyApplication.CallMsgBox( IDUserCantDoThat ) then check the MBAnswer upon return, such as a yes/no/cancel or whatever. In the database table, I would have things like what the messagebox title would be, the buttons that would be shown, the actual message, a special flag that automatically tacked on a subsequent standard comment like "Please contact help desk if this happens.". The function would call the messagebox with all applicable settings and just return back the answer. The big benefits of this was, one location to have all the "context" of messages, and via constants, easier to read what message was going to be presented to the user. Does anyone have a similar system in .Net to do a similar approach, or is this just a bad idea in the .Net environment.

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  • Best practice on structuring asynchronous mailers (using Sidekiq)

    - by gbdev
    Just wondering what's the best way to go about structuring asynchronous mailers in my Rails app (using Sidekiq)? I have one ActionMailer class with multiple methods/emails... notifier.rb: class Notifier < ActionMailer::Base default from: "\"Company Name\" <[email protected]>" default_url_options[:host] = Rails.env.production? ? 'domain.com' : 'localhost:5000' def welcome_email(user) @user = user mail to: @user.email, subject: "Thanks for signing up!" end ... def password_reset(user) @user = user @edit_password_reset_url = edit_password_reset_url(user.perishable_token) mail to: @user.email, subject: "Password Reset" end end Then for example, the password_reset mail is sent in my User model by doing... user.rb: def deliver_password_reset_instructions! reset_perishable_token! NotifierWorker.perform_async(self) end notifier_worker.rb: class NotifierWorker include Sidekiq::Worker sidekiq_options queue: "mail" def perform(user) Notifier.password_reset(user).deliver end end So I guess I'm wondering a couple things here... Is it possible to define many "perform" actions in one single worker? By doing so I could keep things simple (one notifier/mail worker) as I have it and send many different emails through it. Or should I create many workers? One for each mailer (e.g. WelcomeEmailWorker, PasswordResetWorker, etc) and just assign them all to use the same "mail" queue with Sidekiq. I know it works as it is, but should I break out each of those mail methods (welcome_email, password_reset, etc) into individually mailer classes or is it ok to have them all under one class like Notifier? Really appreciate any advice here. Thanks!

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  • Why do I have to specify pure virtual functions in the declaration of a derived class in Visual C++?

    - by neuviemeporte
    Given the base class A and the derived class B: class A { public: virtual void f() = 0; }; class B : public A { public: void g(); }; void B::g() { cout << "Yay!"; } void B::f() { cout << "Argh!"; } I get errors saying that f() is not declared in B while trying do define void B::f(). Do I have to declare f() explicitly in B? I think that if the interface changes I shouldn't have to correct the declarations in every single class deriving from it. Is there no way for B to get all the virtual functions' declarations from A automatically? EDIT: I found an article that says the inheritance of pure virtual functions is dependent on the compiler: http://www.objectmentor.com/resources/articles/abcpvf.pdf I'm using VC++2008, wonder if there's an option for this.

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  • Inefficient 'ANY' LINQ clause

    - by Focus
    I have a query that pulls back a user's "feed" which is essentially all of their activity. If the user is logged in the query will be filtered so that the feed not only includes all of the specified user's data, but also any of their friends. The database structure includes an Actions table that holds the user that created the action and a UserFriends table which holds any pairing of friends using a FrienderId and FriendeeId column which map to UserIds. I have set up my LINQ query and it works fine to pull back the data I want, however, I noticed that the query gets turned into X number of CASE clauses in profiler where X is the number of total Actions in the database. This will obviously be horrible when the database has a user base larger than just me and 3 test users. Here's the SQL query I'm trying to achieve: select * from [Action] a where a.UserId = 'GUID' OR a.UserId in (SELECT FriendeeId from UserFriends uf where uf.FrienderId = 'GUID') OR a.UserId in (SELECT FrienderId from UserFriends uf where uf.FriendeeId = 'GUID') This is what I currently have as my LINQ query. feed = feed.Where(o => o.User.UserKey == user.UserKey || db.Users.Any(u => u.UserFriends.Any(ufr => ufr.Friender.UserKey == user.UserKey && ufr.isApproved) || db.Users.Any(u2 => u2.UserFriends.Any(ufr => ufr.Friendee.UserKey == user.UserKey && ufr.isApproved) ))); This query creates this: http://pastebin.com/UQhT90wh That shows up X times in the profile trace, once for each Action in the table. What am I doing wrong? Is there any way to clean this up?

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  • A public struct inside a class

    - by Koning Baard
    I am new to C++, and let's say I have two classes: Creature and Human: /* creature.h */ class Creature { private: public: struct emotion { /* All emotions are percentages */ char joy; char trust; char fear; char surprise; char sadness; char disgust; char anger; char anticipation; char love; }; }; /* human.h */ class Human : Creature { }; And I have this in my main function in main.cpp: Human foo; My question is: how can I set foo's emotions? I tried this: foo->emotion.fear = 5; But GCC gives me this compile error: error: base operand of '-' has non-pointer type 'Human' This: foo.emotion.fear = 5; Gives: error: 'struct Creature::emotion' is inaccessible error: within this context error: invalid use of 'struct Creature::emotion' Can anyone help me? Thanks P.S. No I did not forget the #includes

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  • WCF data services - Limiting related objects returned based on critera

    - by Mike Morley
    I have an object graph consisting of a base employee object, and a set of related message objects. I am able to return the employee objects based on search criteria on the employee properties (eg team) etc. However, if I expand on the messages, I get the full collection of messages back. I would like to be able to either take the top n messages (i.e. restrict to 10 most recent) or ideally use a date range on the message objects to limit how many are brought back. So far I have not been able to figure out a way of doing this: I get an error if I attempt to filter on properties on the message (&$filter=employee/message/StartDate gives an error "No property 'StartDate' exists in type 'System.Data.Objects.DataClasses.EntityCollection`1). Attempting to use Top on the message related object doesn't work either. I have also tried using a WebGet extension that takes a string list of employee IDs. That works until the list gets too long, and then fails due to the URL getting too long (it might be possible to setup a paging mechanism on this approach)... Unfortunately the UI control I am using requires the data to be in a fairly specific hierarchical shape, so I can't easily come at this from starting on the message side and working backwards. Outside of making multiple calls does anyone know of a method to accomplish this with wcf data services? Thanks! M.

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  • Why `is_base_of` works with private inheritance?

    - by Alexey Malistov
    Why the following code works? typedef char (&yes)[1]; typedef char (&no)[2]; template <typename B, typename D> struct Host { operator B*() const; operator D*(); }; template <typename B, typename D> struct is_base_of { template <typename T> static yes check(D*, T); static no check(B*, int); static const bool value = sizeof(check(Host<B,D>(), int())) == sizeof(yes); }; //Test sample class B {}; class D : private B {}; //Exspression is true. int test[is_base_of<B,D>::value && !is_base_of<D,B>::value]; Note that B is private base. Note that operator B*() is const. How does this work? Why this works? Why static yes check(D*, T); is better than static yes check(B*, int); ?

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  • Portable Eclipse

    - by Jeach
    I'm trying to port my entire 'workspace' to a USB key (including the Eclipse executable) so that I can carry my work anywhere with me and work off the key directly. My directory hierarchy is similar to this: /workspace/eclipse - Where my current eclipse binary is stored /workspace/codebase - Where I keep the root of all my eclipse projects /workspace/resources - Where I keep all project files (images, docs, libs, etc.) It all works perfectly fine on one system. But when I change over to another system, the USB key gets mounted on another drive. For example, on my laptop, I get 'E:\', on my PC, I get 'K:\' and at work I get 'F:\', etc, etc. This means that because Eclipse (for 'some' reason) seems to only use full path names (including driver letters) in every single one of its configuration files (such as .classpath), nothing ever works when I want to work on another system. I put a 'libs' directory in the base of every project and populate it with its dependent JAR files. Why doesn't it use relative names instead, so that I could specify something like "../../libs/log4j.jar"? Anyone know how to fix this problem? Does anyone know of a workaround for this? For some reason, I really doubt I'm the first developer to do this! Thanks for your help and any suggestions.

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  • Trapping messages in .NET

    - by user350632
    How can i trap a Windows system message (like WM_SETTEXT) that was sent by some window (VLC player window in my case)? I've tried to inherit NativeWindow class and override WndProc like this: class VLCFilter : NativeWindow { System.IntPtr iHandle; const int WM_SETTEXT = 0x000C; public VLCFilter() { Process p = Process.GetProcessesByName("vlc")[0]; iHandle = p.MainWindowHandle; } protected override void WndProc(ref Message aMessage) { base.WndProc(ref aMessage); if (aMessage.HWnd != iHandle) return false; if (aMessage.Msg == WM_SETTEXT) { MessageBox.Show("VLC window text changed!"); } } } I have checked with Microsoft Spy++ that WM_SETTEXT message is sent by VLC player but my code doesn't seem to get the work done. I've refered mainly to: http://www.codeproject.com/kb/dotnet/devicevolumemonitor.aspx I'm trying to make this work for some time with no success. What am I doing wrong? What I am not doing? Maybe there is easier way to do this? My initial goal is to catch when VLC player (that could be playing somewhere in the background and is not emmbed in my application) repeats its playback (have noticed that WM_SETTEXT message is sent then and I'm trying to find it out like this).

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  • Mono Text Based Web Browser

    - by powerbox
    Hi guys, is there any public text based web browser implementation for C# or on mono base api that I can use to fill up web forms automatically? I'll be using it to automate some web task that does not require any image authentication. I'm currently using a web browser control available on .Net Framework and waits for the event WebBrowserDocumentCompletedEventHandler to fire after a page is successfully loaded and invoke some actions like Submit or simulating a mouse click on some links. It actually does the job but I can't process bulk transactions since I needed to wait for the whole page to be loaded together with the images and other stuff. It is easy to use HttpWebRequest to fill up some forms , provide some data and then submit. But on some occasions I only need to simulate a mouse click to a certain link which I don't know how to do with HttpWebRequest. By the way using HttpWebRequest will still download all the images of a web page that I see pointless since I only need to provide correct data back to the server. I hope someone can pinpoint me the correct way of doing this kind of automation and thanks in advance!

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  • How can I add SOAP Headers to a WSDL generated Borland C++ Builder 6 application.

    - by MJG
    Using a WSDL that requires a SOAP HEADER for Authentication (fragment below) code that gets generated when creating a web service client via the "WSDL Importer" has no concept of the Authentication Headers and there are no examples in BCB6 C++ Examples/WebServices directories that show how, and nothing on Web that I can find. Anyone with BCB6 C++ (not Delphi) have an example of adding SOAP Headers to a TRemotable subclass? <s:element name="AuthenticationHeader" type="tns:AuthenticationHeader"/> <s:complexType name="AuthenticationHeader"> <s:complexContent mixed="false"> <s:extension base="tns:UserAuthHeader"> <s:sequence> <s:element minOccurs="0" maxOccurs="1" name="Function" type="s:string"/> <s:element minOccurs="1" maxOccurs="1" name="TimeOutMilliSec" type="s:int"/> </s:sequence> </s:extension> </s:complexContent> </s:complexType> <s:complexType name="UserAuthHeader"> <s:sequence> <s:element minOccurs="0" maxOccurs="1" name="Username" type="s:string"/> <s:element minOccurs="0" maxOccurs="1" name="Password" type="s:string"/> </s:sequence> <s:anyAttribute/> </s:complexType>

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  • Do you ever make a code change and just test rather than trying to fully understand the change you'v

    - by Clay Nichols
    I'm working in a 12 year old code base which I have been the only developer on. There are times that I'll make a a very small change based on an intuition (or quantum leap in logic ;-). Usually I try to deconstruct that change and make sure I read thoroughly the code. However sometimes, (more and more these days) I just test and make sure it had the effect I wanted. (I'm a pretty thorough tester and would test even if I read the code). This works for me and we have surprisingly (compared to most software I see) few bugs escape into the wild. But what I'm wondering is whether this is just the "art" side of coding. Yes, in an ideal world you would exhaustively read every bit of code that your change modified, but I in practice, if you're confident that it only affects a small section of code, is this a common practice? I can obviously see where this would be a disastrous approach in the hands of a poor programmer. But then, I've seen programmers who ostensibly are reading the code and break stuff left and right (in their own code based which only they have been working on).

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  • Unit testing a method with many possible outcomes

    - by Cthulhu
    I've built a simple~ish method that constructs an URL out of approximately 5 parts: base address, port, path, 'action', and a set of parameters. Out of these, only the address part is mandatory, the other parts are all optional. A valid URL has to come out of the method for each permutation of input parameters, such as: address address port address port path address path address action address path action address port action address port path action address action params address path action params address port action params address port path action params andsoforth. The basic approach for this is to write one unit test for each of these possible outcomes, each unit test passing the address and any of the optional parameters to the method, and testing the outcome against the expected output. However, I wonder, is there a Better (tm) way to handle a case like this? Are there any (good) unit test patterns for this? (rant) I only now realize that I've learned to write unit tests a few years ago, but never really (feel like) I've advanced in the area, and that every unit test is a repeat of building parameters, expected outcome, filling mock objects, calling a method and testing the outcome against the expected outcome. I'm pretty sure this is the way to go in unit testing, but it gets kinda tedious, yanno. Advice on that matter is always welcome. (/rant) (note) christmas weekend approaching, probably won't reply to suggestions until next week. (/note)

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  • Margically appearing margin in footer. Could use some fresh eye's on this.

    - by Banderdash
    Hi chaps! Got a nearly finished coded comp here: http://clients.pixelbleed.net/biodesign/ I realize it's not completely valid, what with my nesting of li's and ul's within A tags. Unfortunately that's the way it has to be. My issue is with the very bottom of the footer. It has a space showing the body's background color beneath it. Tried a number of things and this space after the black link bar on the very bottom is a resistant little bugger. Ideally the black box on the bottom should rest against the very base of the view-port, at least when the content is sufficiently long--which it is in this case. If someone would like to take a quick peak at my source and give me some ideas I'd be very grateful. The CSS can be found here: http://clients.pixelbleed.net/biodesign/css/core.css And, yes, I've tried removing the height:100%. Makes no difference it seems. I do believe the issue to be with the footer, as when I remove these Div's the content rests as it should. Just don't see anything in my CSS to cause the margin/spacing issue though. Thanks so much.

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  • Problems with binding to Window Height and Width

    - by D.H.
    I have some problems when I try to bind the height and width of a window to properties in my view model. Here is a small sample app to illustrate the problem. This is the code in app.xaml.xs public partial class App : Application { protected override void OnStartup(StartupEventArgs e) { base.OnStartup(e); MainWindow mainWindow = new MainWindow(); MainWindowViewModel mainWindowViewModel = new MainWindowViewModel(); mainWindow.DataContext = mainWindowViewModel; mainWindow.Show(); } } This is MainWindow.xaml: <Window x:Class="TestApp.MainWindow" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" Height="{Binding WindowHeight}" Width="{Binding WindowWidth}" BorderThickness="{Binding WindowBorderThickness}"> </Window> And this is the view model: public class MainWindowViewModel { public int WindowWidth { get { return 100; } } public int WindowHeight { get { return 200; } } public int WindowBorderThickness { get { return 8; } } } When the program is started the getters of WindowHeight and WindowBorderThickness (but not WindowWidth) are called, so the height and the border of the window is set properly, but not the width. I then add button that will trigger PropertyChanged for all properties, so that the view model now looks like this: public class MainWindowViewModel : INotifyPropertyChanged { public event PropertyChangedEventHandler PropertyChanged; public void TriggerPropertyChanges() { if (PropertyChanged != null) { PropertyChanged(this, new PropertyChangedEventArgs("WindowWidth")); PropertyChanged(this, new PropertyChangedEventArgs("WindowHeight")); PropertyChanged(this, new PropertyChangedEventArgs("WindowBorderThickness")); } } public ICommand ButtonCommand { get { return new RelayCommand(delegate { TriggerPropertyChanges(); }); } } public int WindowWidth { get { return 100; } } public int WindowHeight { get { return 200; } } public int WindowBorderThickness { get { return 8; } } } Now, when I click the button, the getter of WindowBorderThickness is called, but not the ones for WindowWidth and WindowHeight. It all just seems very weird and inconsistent to me. What am I missing?

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  • Deserialization of a DataSet... deal with column name changes? how to migrate data from one column to another?

    - by Brian Kennedy
    So, we wanted to slightly generalize a couple columns in our typed dataset... basically dropped a foreign key constraint and then wanted to change a couple column names to better reflect their new state. All that is easy. The problem is that our users may have serialized out the old version of the DataSet as XML. We want to be able to read those old XML files and deserialize them into the revised DataSet. It seems that would be a fairly common desire... but I haven't yet figured out the right thing to search the internet for. One possible solution would seem to be some way to give a DataColumn an alias or alternate name such that when it reads the old column name, it knows that data can be read into the column with the new column name. I can find no support for any such thing. Another approach would seem to be an "after deserialization" method of some sort... so, I would let it read in the old column values into a normal DataColumn with that name, and then in the "after deserialization" method I would just move the data from the obsolete column into the new column, and then delete the old columns. That would seem to generalize to many other situations... and having such events or hooks is pretty common in ADO.NET. But I have looked for such a hook and haven't yet found it. If no "after deserialization" hook, it would seem I ought to be able to override ReadXml or ReadXmlSerializable methods to call the base and then do my "after" stuff to fix up old data into new. But it does not appear that is possible. Soooo, I have to think backward compatibility with old serialized DataSets and simple data migration would be a well-solved problem... so, trying to reinvent that wheel seems silly. But so far, I haven't seemed to find any documentation on doing those things. Suggestions? What is best practice for this?

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  • Index question: Select * with WHERE clause. Where and how to create index

    - by Mestika
    Hi, I’m working on optimizing some of my queries and I have a query that states: select * from SC where c_id ="+c_id” The schema of ** SC** looks like this: SC ( c_id int not null, date_start date not null, date_stop date not null, r_t_id int not null, nt int, t_p decimal, PRIMARY KEY (c_id, r_t_id, date_start, date_stop)); My immediate bid on how the index should be created is a covering index in this order: INDEX(c_id, date_start, date_stop, nt, r_t_id, t_p) The reason for this order I base on: The WHERE clause selects from c_id thus making it the first sorting order. Next, the date_start and date_stop to specify a sort of “range” to be defined in these parameters Next, nt because it will select the nt Next the r_t_id because it is a ID for a specific type of my r_t table And last the t_p because it is just a information. I don’t know if it is at all necessary to order it in a specific way when it is a SELECT ALL statement. I should say, that the SC is not the biggest table. I can say how many rows it contains but a estimate could be between <10 and 1000. The next thing to add is, that the SC, in different queries, inserts the data into the SC, and I know that indexes on tables which have insertions can be cost ineffective, but can I somehow create a golden middle way to effective this performance. Don't know if it makes a different but I'm using IBM DB2 version 9.7 database Sincerely Mestika

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  • Speed comparison - Template specialization vs. Virtual Function vs. If-Statement

    - by Person
    Just to get it out of the way... Premature optimization is the root of all evil Make use of OOP etc. I understand. Just looking for some advice regarding the speed of certain operations that I can store in my grey matter for future reference. Say you have an Animation class. An animation can be looped (plays over and over) or not looped (plays once), it may have unique frame times or not, etc. Let's say there are 3 of these "either or" attributes. Note that any method of the Animation class will at most check for one of these (i.e. this isn't a case of a giant branch of if-elseif). Here are some options. 1) Give it boolean members for the attributes given above, and use an if statement to check against them when playing the animation to perform the appropriate action. Problem: Conditional checked every single time the animation is played. 2) Make a base animation class, and derive other animations classes such as LoopedAnimation and AnimationUniqueFrames, etc. Problem: Vtable check upon every call to play the animation given that you have something like a vector<Animation>. Also, making a separate class for all of the possible combinations seems code bloaty. 3) Use template specialization, and specialize those functions that depend on those attributes. Like template<bool looped, bool uniqueFrameTimes> class Animation. Problem: The problem with this is that you couldn't just have a vector<Animation> for something's animations. Could also be bloaty. I'm wondering what kind of speed each of these options offer? I'm particularly interested in the 1st and 2nd option because the 3rd doesn't allow one to iterate through a general container of Animations. In short, what is faster - a vtable fetch or a conditional?

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  • Upgrade to iPhone 3.0 sdk and now simulator shows blank screen.

    - by NoShitMcGee
    I have an iPhone app that uses an UITabBarController, which contains two UINavigationControllers, each of which in turn contains one or more TableViewControllers (actually, customized UIViewControllers implementing UITableViewDelegate and UITableViewDataSource. ) On launch, it displays the UITabBarController with one of the tableviews displayed. Everything is coded; Interface Builder was NOT used to make any of the UI stuff. It was written in SDK 2. It worked fine in sdk 2. I recently updated to SDK 3.0. In Info, I set the Base SDK setting to iPhone Simulator 3.0. Now, when I launch the application in Simulator, I see only a blank white screen with the status bar at the top. No signs of my app. However, when I exit the app, the missing tableview displays briefly as the exiting animation is playing. Also, on the blank white screen I can still click where the navigation buttons should be and find that, when I exit the app and the missing screen briefly displays, that navigation has taken me to another screen. So the buttons work, and presumably the tableviewcells are there, they just cannot be seen. Has anyone seen anything like this? Does anyone have any idea what is causing it and how I can fix it? I noticed that sample apps, such as SQLiteBooks, seem to work fine when updating to SDK 3.0. My app isn't very much different from SQLiteBooks in terms of technologies used, except that, as I said above, I do not use Interface Builder. Thanks

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