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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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• Is passing a struct value to a method by-reference in C# an acceptable optimization?

  - by Arc

  Say I have a struct: struct MyStruct { public int X public int Y } And a method in some class that is iterated over many times elsewhere: public bool MyMethod( MyStruct myStruct ) { return ... } Is changing the MyMethod signature to the following an acceptable optimization? public bool MyMethod( ref MyStruct myStruct ) If so, how much of an advantage would it really be? If not, about how many fields would a struct need for a big enough advantage using ref this way?

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• Should i use TabContainer for multiple pages?

  - by Tim

  I'm considering if it is a good idea to use an ASP.Net TabContainer-Control in the way that every TabPanel contains content of a different page. For example: Next i want to implement in my application is the masterdata management. Normally i would create one aspx page for every masterdata-table (f.e. Customer - MD_Customer.aspx). Then i would add a link into my Menu to this page. Now i'm thinking of creating one aspx page for all(Masterdata.aspx) with a Tabcontainer and an UpdatePanel for every type of Masterdata. The link it the menu could have an additional MDType as URL-Parameter. My main concerns are related to performance(one "page" for every TabPanel currently means 7 "pages" in one) and maintainability because of increasing complexity. Is it a good approach or a bad idea? Thanks

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• How can I get a property as an Entity in Action of Asp.Net Mvc ?

  - by Felipe

  Hi all, i'd like to know how can I get a property like an entity, for example: My Model: public class Product { public int Id { get; set; } public string Name { get; set; } public Category Category { get; set; } } View: Name: <%=Html.TextBoxFor(x => x.Name) %> Category: <%= Html.DropDownList("Category", IEnumerable<SelectListItem>)ViewData["Categories"]) %> Controller: public ActionResult Save(Product product) { /// produtct.Category ??? } and how is the category property ? It's fill by the view ? ASP.Net MVC know how to fill this object by ID ? Thanks!

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• Should I use a huge composite primary key or just a unique id?

  - by Jack

  I have been trying to do web scraping of a particular site and storing the results in a database. My original assumptions about the data allowed a schema where I could use fairly reasonable composite primary keys (usually containing only 2 or 3 fields) but as time went on, I realized that my original assumptions about the data were wrong and my primary keys were not as unique as I thought they were, so I have slowly been expanding them to contain more and more fields. In fact, I have recently come to believe that their database has no constraints whatsoever. Just today, I have finally expanded my a primary key for one of my tables to contain every field in that table and I thought now would be a good time to ask: is it better to add an auto-incrementing column that is just a unique id or just leave a composite primary key on the entire table?

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• Voting Script, Possiblity of Simplifying Database Queries

  - by Sev

  I have a voting script which stores the post_id and the user_id in a table, to determine whether a particular user has already voted on a post and disallow them in the future. To do that, I am doing the following 3 queries. SELECT user_id, post_id from votes_table where postid=? AND user_id=? If that returns no rows, then: UPDATE post_table set votecount = votecount-1 where post_id = ? Then SELECT votecount from post where post_id=? To display the new votecount on the web page Any better way to do this? 3 queries are seriously slowing down the user's voting experience

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• When designing an event, is it a good idea to prevent listeners from being added twice?

  - by Matt

  I am creating an event-based API where a user can subscribe to an event by adding listener objects (as is common in Java or C#). When the event is raised, all subscribed listeners are invoked with the event information. I initially decided to prevent adding an event listener more than once. If a listener is added that already exists in the listener collection, it is not added again. However, after thinking about it some more, it doesn't seem that most event-based structures actually prevent this. Was my initial instinct wrong? I'm not sure which way to go here. I guess I thought that preventing addition of an existing listener would help to avoid a common programming error. Then again, it could also hide a bug that would lead to code being run multiple times when it shouldn't.

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• Is throwing an exception a healthy way to exit?

  - by ramaseshan

  I have a setup that looks like this. class Checker { // member data Results m_results; // see below public: bool Check(); private: bool Check1(); bool Check2(); // .. so on }; Checker is a class that performs lengthy check computations for engineering analysis. Each type of check has a resultant double that the checker stores. (see below) bool Checker::Check() { // initilisations etc. Check1(); Check2(); // ... so on } A typical Check function would look like this: bool Checker::Check1() { double result; // lots of code m_results.SetCheck1Result(result); } And the results class looks something like this: class Results { double m_check1Result; double m_check2Result; // ... public: void SetCheck1Result(double d); double GetOverallResult() { return max(m_check1Result, m_check2Result, ...); } }; Note: all code is oversimplified. The Checker and Result classes were initially written to perform all checks and return an overall double result. There is now a new requirement where I only need to know if any of the results exceeds 1. If it does, subsequent checks need not be carried out(it's an optimisation). To achieve this, I could either: Modify every CheckN function to keep check for result and return. The parent Check function would keep checking m_results. OR In the Results::SetCheckNResults(), throw an exception if the value exceeds 1 and catch it at the end of Checker::Check(). The first is tedious, error prone and sub-optimal because every CheckN function further branches out into sub-checks etc. The second is non-intrusive and quick. One disadvantage is I can think of is that the Checker code may not necessarily be exception-safe(although there is no other exception being thrown anywhere else). Is there anything else that's obvious that I'm overlooking? What about the cost of throwing exceptions and stack unwinding? Is there a better 3rd option?

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• How to construct objects based on XML code?

  - by the_drow

  I have XML files that are representation of a portion of HTML code. Those XML files also have widget declarations. Example XML file: <message id="msg"> <p> <Widget name="foo" type="SomeComplexWidget" attribute="value"> inner text here, sets another attribute or inserts another widget to the tree if needed... </Widget> </p> </message> I have a main Widget class that all of my widgets inherit from. The question is how would I create it? Here are my options: Create a compile time tool that will parse the XML file and create the necessary code to bind the widgets to the needed objects. Advantages: No extra run-time overhead induced to the system. It's easy to bind setters. Disadvantages: Adds another step to the build chain. Hard to maintain as every widget in the system should be added to the parser. Use of macros to bind the widgets. Complex code Find a method to register all widgets into a factory automatically. Advantages: All of the binding is done completely automatically. Easier to maintain then option 1 as every new widget will only need to call a WidgetFactory method that registers it. Disadvantages: No idea how to bind setters without introducing a maintainability nightmare. Adds memory and run-time overhead. Complex code What do you think is better? Can you guys suggest a better solution?

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• Solving problems with near infinite potential solutions

  - by Zonda333

  Today I read the following problem: Use the digits 2, 0, 1, 1 and the operations +, -, x, ÷, sqrt, ^ , !, (), combinations, and permutations to write equations for the counting numbers 1 through 100. All four digits must be used in each expression. Only the digits 2, 0, 1, 1 may be used, and each must be used exactly once. Decimals may be used, as in .1, .02, etc. Digits may be combined; numbers such as 20 or 101 may be used. Example: 60 = 10*(2+1)!, 54 = ¹¹C2 - 0! Though I was able to quickly find around 50 solutions quite easily in my head, I thought programming it would be a far superior solution. However, I then realized I had no clue how to go about solving a problem like this. I am not asking for complete code for me to copy and paste, but for ideas about how I would solve this problems, and others like it that have nearly infinite potential solutions. As I will be writing it in python, where I have the most experience, I would prefer if the answers were more python based, but general ideas are great too.

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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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• 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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• Static selection and Ruby on Rails objects

  - by Dave

  Hi all- I have a simple problem, but am having trouble wrapping my head around it. I have an video object that should have one or more "genres". This list of genres should be prepopulated and then the user should just select one or more using autocomplete or some such. Here is the question: Is it worth creating a table with genres for the static selection? Or should it just be included in the presentation layer? If there is a static table, how do we name it correctly. I envision something like this class Video < ActiveRecord::Base has_many :genres ... end class Genre < ... belongs_to :video ... end But then we get a table called genre, that basically maps all the selected genres to their parent videos. There would need to be some static table to reference the static genres. Is this the best way to do it? Sorry if this was rambl-y a little stream of conciousness. Thanks!

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• How to simplify the code?

  - by Tattat

  I have objectA, and objectB.... also I have objectAs, and objectBs. the objectA is only have the init method, and ObjectAs have somethings like this: #import "ObjectAs.h" @implementation ObjectAs @synthesize objectAs; -(id) init{ if( (self=[super init])) { self.objectAs = [[NSMutableArray alloc] init]; } return self; } -(int)getObjectAsNumber{ return [self.objectAs count]; } -(void)addObjectA:(ObjectA *)newObjectA{ [self.objectAs addObject:newObjectA]; } -(id)getObjectAByIdx:(int)objectAIdx{ return [self.objectAs objectAtIndex:objectAIdx]; } -(void)dealloc{ [super dealloc]; [objectAs release]; } @end The objectBs have similar have, I know that I can copy and paste, and replace it. Is there any way to simplify the objectBs, and objectAs? thz a lot.

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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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• How to handle request/response propagation up and down a widget hierarchy in a GUI app?

  - by fig-gnuton

  Given a GUI application where widgets can be composed of other widgets: If the user triggers an event resulting in a lower level widget needing data from a model, what's the cleanest way to be able to send that request to a controller (or the datastore itself)? And subsequently get the response back to that widget? Presumably one wouldn't want the controller or datastore to be a singleton directly available to all levels of widgets, or is this an acceptable use of singleton? Or should a top level controller be injected as a dependency through a widget hierarchy, as far down as the lowest level widget that might need that controller? Or a different approach entirely?

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• Where are good examples of Web applications built for skilled and intense use?

  - by ProfK

  I have spent most of my development career writing backend code, or front-end apps for used as daily business tools, by at least semi-skilled staff, e.g. order-tracking, sales capture, etc. That those I helped build peformed their tasks well is comfort enough, but I am still seeking excellence in the building of these kind of apps, versus the more trendy emphasis on slow and sensual interpersonal relationships with the UI. Can anyone recommend reading on this type of application (LOB?) on the web today? Any available examples to study?

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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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• Why is there "data" and "newtype" in Haskell?

  - by martingw

  To me it seems that a newtype definition is just a data definition that obeys some restrictions (only one constructor and such), and that due to these restrictions the runtime system can handle newtypes more efficiently. Ok, and the handling of pattern matching for undefined values is slightly different. But suppose Haskell would only knew data definitions, no newtypes: Couldn't the compiler find out for himself whether a given data definition obeys these restrictions, and automatically treat it more efficiently? I'm sure I'm missing out on something, these Haskell designers are so clever, there must be some deeper reason for this...

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• Why is it impossible to override a getter-only property and add a setter?

  - by ripper234

  Why do you think (or, why is it good that) Microsoft chose not to allow: public abstract class BaseClass { public abstract int Bar { get;} } public class ConcreteClass : BaseClass { public override int Bar { get { return 0; } set {} } }

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• The best way to structure this database?

  - by James P

  At the moment I'm doing this: gems(id, name, colour, level, effects, source) id is the primary key and is not auto-increment. A typical row of data would look like this: id => 40153 name => Veiled Ametrine colour => Orange level => 80 effects => +12 sp, +10 hit source => Ametrine (Some of you gamers might see what I'm doing here :) ) But I realise this could be sorted a lot better. I have studied database relationships and secondary keys in my A-Level computing class but never got as far as to set one up properly. I just need help with how this database should be organised, like what tables should have what data with what secondary and foreign keys? I was thinking maybe 3 tables: gem, effects, source. Which then have relationships to each other? Can anyone shed some light on this? Is a complex way like I'm proposing really the way to go or should I just carry on with what I'm doing? Cheers.

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• What's the best way to handle modules that use each other?

  - by Axeman

  What's the best way to handle modules that use each other? Let's say I have a module which has functions for hashes: # Really::Useful::Functions::On::Hash.pm use base qw<Exporter>; use strict; use warnings; use Really::Useful::Functions::On::List qw<transform_list>; our @EXPORT_OK = qw<transform_hash transform_hash_as_list ...>; #... sub transform_hash { ... } #... sub transform_hash_as_list { return transform_list( %{ shift() } ); } #... 1 And another module has been segmented out for lists: # Really::Useful::Functions::On::List.pm use base qw<Exporter>; use strict; use warnings; use Really::Useful::Functions::On::Hash qw<transform_hash>; our @EXPORT_OK = qw<transform_list some_func ...>; #... sub transform_list { ... } #... sub some_func { my %params = transform_hash @_; #... } #... 1 Suppose that enough of these utility functions are handy enough that I'll want to use them in BEGIN statements and import functions to process parameter lists or configuration data. I have been putting sub definitions into BEGIN blocks to make sure they are ready to use whenever somebody includes the module. But I have gotten into hairy race conditions where a definition is not completed in a BEGIN block. I put evolving code idioms into modules so that I can reuse any idiom I find myself coding over and over again. For instance: sub list_if { my $condition = shift; return unless $condition; my $more_args = scalar @_; my $arg_list = @_ > 1 ? \@_ : @_ ? shift : $condition; if (( reftype( $arg_list ) || '' ) eq 'ARRAY' ) { return wantarray ? @$arg_list : $arg_list; } elsif ( $more_args ) { return $arg_list; } return; } captures two idioms that I'm kind of tired of typing: @{ func_I_hope_returns_a_listref() || [] } and ( $condition ? LIST : ()) The more I define functions in BEGIN blocks, the more likely I'll use these idiom bricks to express the logic the more likely that bricks are needed in BEGIN blocks. Do people have standard ways of dealing with this sort of language-idiom-brick model? I've been doing mostly Pure-Perl; will XS alleviate some of this?

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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 books should be on the modern data warehouse architect's shelf?

  - by McPeterson

  I have a few on mine. Basically just the set of Kimball books: The Data Warehouse LifeCycle The Data Warehouse ETL Toolkit The Data Warehouse Toolkit Are there any others that should be included? Or any other good ones you know? -mcpeterson

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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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