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  • Objective-C, .m / .mm performance difference?

    - by Sam
    I tend to use the .mm extension by default when creating new classes so that I can use ObjC++ later on if I require it. Is there any disadvantage to doing this? When would you prefer .m? Does .m compile to a faster executable (since C is generally faster than C++)?

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  • Sharepoint bug database - any good?

    - by jkohlhepp
    We've been using Sharepoint as a poor man's bug tracking database for the last couple of projects that we did. No one is really happy with the solution so I'm looking for alternatives. I happened to stumble upon the Bug Database Template for Sharepoint. If it is halfway decent it might be a good choice for us since the transition would be smooth as the team is already used to Sharepoint. Anyone have any experience using this template? Any major problems? Any major missing features? Is there any documentation out there beyond that download page? Thanks for the help.

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  • SQLite vs Firebird

    - by rwallace
    The scenario I'm looking at is "This program uses Postgres. Oh, you want to just use it single-user for the moment, and put off having to deal with installing a database server? Okay, in the meantime you can use it with the embedded single-user database." The question is then which embedded database is best. As I understand it, the two main contenders are SQLite and Firebird; so which is better? Criteria: Full SQL support, or as close as reasonably possible. Full text search. Easy to call from C# Locks, or allows you to lock, the database file to make sure nobody tries to run it multiuser and ends up six months down the road with intermittent data corruption in all their backups. Last but far from least, reliability. As I understand it, the disadvantages of SQLite are, No right outer join. Workaround: use left outer join instead. Not much integrity checking. Workaround: be really careful in the application code. No decimal numbers. Workaround: lots of aspirin. None of the above are showstoppers. Are there any others I'm missing? (I know it doesn't support some administrative and code-within-database SQL features, that aren't relevant for this kind of use case.) I don't know anything much about Firebird. What are its disadvantages?

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  • Windows based Apache/PHP/Perl/database stacks

    - by GreenMatt
    Does anyone know if XAMPP's Perl also provides Tk support? Does anyone know of a similar stack which provides PostresSQL in addition to/instead of MySQL? I'd like this to run on Win 7 and XP. Edit: I do know I could install the other components I want "by hand", for example getting Tk from CPAN, I'd just prefer to get everything at one time if possible.

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  • ItemsControl.ItemsSource MVVM performance

    - by bitbonk
    I have an (non-virtualized) ItemsControl that binds its ItemsSource to a ObeservableCollection of ViewModel instances. Now once the large amount Model instances is loaded all the ViewModel complemnents needs to be added to that ObservableCollection. How can I add a large amount of ViewModels without making the UI Thread hang? I suppose the UI Thread hangs because each time a new item is added the ItemsControl needs to update itself and does layout etc. over and over again. Should I suspend the binding add all items and then resume? If so, how? Should I override the ObservableCollection to implement an AddRange so only 1 CollectionChanged Event is fired for adding multiple items? Or alternatively just replace the whole collection? Or is it better to add each items separately and call Dispatcher.Invoke for each item separately? So I would unblock frequently. How do you handle large dynamic lists that can not be virtualized?

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  • [.NET Performance Counter] "System.ComponentModel.Win32Exception: Access is denied" is thrown when c

    - by Ricky
    Hi guys: Calling PerformanceCounterCategory.Create() below on my machine thorws out this exception: System.ComponentModel.Win32Exception: Access is denied Do you know what's the issue about it? Thank you! if (!PerformanceCounterCategory.Exists("MyCategory")) { CounterCreationDataCollection counters = new CounterCreationDataCollection(); CounterCreationData avgDurationBase = new CounterCreationData(); avgDurationBase.CounterName = "average time per operation base"; avgDurationBase.CounterHelp = "Average duration per operation execution base"; avgDurationBase.CounterType = PerformanceCounterType.AverageBase; counters.Add(avgDurationBase); // create new category with the counters above PerformanceCounterCategory.Create("MyCategory", "Sample category for Codeproject", PerformanceCounterCategoryType.SingleInstance, counters); }

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  • Why is drawing to OnPaint graphics faster than image graphics?

    - by Tesserex
    I'm looking for a way to speed up the drawing of my game engine, which is currently the significant bottleneck, and is causing slowdowns. I'm on the verge of converting it over to XNA, but I just noticed something. Say I have a small image that I've loaded. Image img = Image.FromFile("mypict.png"); We have a picturebox on the screen we want to draw on. So we have a handler. pictureBox1.Paint += new PaintEventHandler(pictureBox1_Paint); I want our loaded image to be tiled on the picturebox (this is for a game, after all). Why on earth is this code: void pictureBox1_Paint(object sender, PaintEventArgs e) { for (int y = 0; y < 16; y++) for (int x = 0; x < 16; x++) e.Graphics.DrawImage(image, x * 16, y * 16, 16, 16); } over 25 TIMES FASTER than this code: Image buff = new Bitmap(256, 256, PixelFormat.Format32bppPArgb); // actually a form member void pictureBox1_Paint(object sender, PaintEventArgs e) { using (Graphics g = Graphics.FromImage(buff)) { for (int y = 0; y < 16; y++) for (int x = 0; x < 16; x++) g.DrawImage(image, x * 16, y * 16, 16, 16); } e.Graphics.DrawImage(buff, 0, 0, 256, 256); } To eliminate the obvious, I've tried commenting out the last e.Graphics.DrawImage (which means I don't see anything, but it gets rid a call that isn't in the first example). I've also left in the using block (needlessly) in the first example, but it's still just as blazingly fast. I've set properties of g to match e.Graphics - things like InterpolationMode, CompositingQuality, etc, but nothing I do bridges this incredible gap in performance. I can't find any difference between the two Graphics objects. What gives? My test with a System.Diagnostics.Stopwatch says that the first code snippet runs at about 7100 fps, while the second runs at a measly 280 fps. My reference image is VS2010ImageLibrary\Objects\png_format\WinVista\SecurityLock.png, which is 48x48 px, and which I modified to be 72 dpi instead of 96, but those made no difference either.

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  • Managing database connections in an Android Activity

    - by Daniel Lew
    I have an application with a ListActivity that uses a CursorAdapter as its adapter. The ListActivity opens the database and does the querying for the CursorAdapter, which is all well and good, but I am having issues with figuring out when to close both the Cursor and the SQLiteDatabase. The way things are handled right now, if the user finishes the activity, I close the database and the cursor. However, this still ends up with the DalvikVM warning me that I've left a database open - for example, if the user hits the "home" button (leaving the activity in the task's stack), rather than the "back" button. If I close them during pause and then re-query during resume, then I don't get any errors, but then a user cannot return to the list without it requerying (and thus losing the user's place in the list). By this I mean, the user can click on any item in the list and open a new activity based on it, but will often want to hit "back" afterwards and return to the same place on the list. If I requery, then I cannot return the user back to the correct spot. What is the proper way to handle this issue? I want the list to remain scrolled properly, but I don't want the VM to keep complaining about unclosed databases. Edit: Here's a general outline of how I handle the code at the moment: public class MyListActivity extends ListActivity { private Cursor mCursor; private CursorAdapter mAdapter; protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); mAdapter = new MyCursorAdapter(this); setListAdapter(mAdapter); } protected void onPause() { super.onPause(); if (isFinishing()) { mCursor.close(); } } protected void onDestroy() { super.onDestroy(); mCursor.close(); } private void updateQuery() { // If we had a cursor open before, close it. if (mCursor != null) { mCursor.close(); } MyDbHelper dbHelper = new MyDbHelper(this); SQLiteDatabase db = dbHelper.getReadableDatabase(); mCursor = db.query(...); mAdapter.changeCursor(mCursor); db.close(); } } updateQuery() can be called multiple times because the user can filter the results via menu items (I left this part out of the code, as the problem still occurs even if the user does no filtering). Again, the issue is that when I hit home I get leak errors. Yet, after going home, I can go back to the app and find my list again - cursor fully intact.

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  • Drupal 6 vs Drupal 7 performance

    - by lifecoder
    Hi all. I want to start new project and stuck without idea what version to use. I have huge expirience with D6, and also one project (module developement) for D7. It looks like D7 slower, have bigger memory consumption and also have a lack of documentation by the moment. I don't need new CCK, Views and other - looks like I'll coding all features needed as modules. Is D7 have sweet parts now, or better way is develop project under D6? What way you choose for yourself, and why?

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  • Install Sybase SQL Anywhere 11 as service

    - by 5YrsLaterDBA
    we are using Sybase SQL Anywhere 11. I am using command line to install/init database, dbinit -dba %username%,%pwd% -p 4k %dbLocation%, and start database server, dbsrv11 %dbLocation%, in a batch file. What I really want is install my database as Windows service and can be start/running automatically when machine get reboot. But I want to keep using batch for easy intall/uninstall/change it. Any Sybase expert here?

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  • Optimizations employed by ORM's

    - by Kartoch
    I'm teaching JEE, especially JPA, Spring and Spring MVC. As I have not so much experience in large projects, it is difficult to know what to present to students about optimisation of ORM. At the present time, I present some classic optimisation tricks: prepared statements (most of ORM implicitely uses it by default) first and second-level caches "write first, optimize later" it is possible to switch off ORM and send SQL commands directly to the database for very frequent, specialized and costly requests Is there any other point the community see about other way to optimize ORM ? I'm especially interested by DAO patterns...

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  • MSSQL EXPRESS 2008 Stored Procedure execution time spikes periodically

    - by user156241
    I have a big stored procedure on a MSSQL 2008 Express SP2 database that gets run about every 200 ms. Normal execution time is about 50ms. What I am seeing is large inconsistencies in this run time. It will execute for while, say 50-100 times at 40-60ms which is expected, then seemingly at random the same stored procedure will take way longer, say 900ms or 1.5 seconds to run. Sometimes more than one call of the same procedure in a row will take longer too. It appears that something is causing sql server to slow down dramatically every minute or so, but I can't figure out what. There is no timing pattern between the occurences. I have the same setup on two different computers, one of which is a clean XP Pro load with no virus checking and nothing installed except SQL server. Also, The recovery options for all the databases are set to "Simple".

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  • Recommendation for high performance WPF Chart

    - by Ajaxx
    We're working on a WPF-based desktop application that charts financial markets information (candlestick charts, overlayed indicator curves, volume, etc). The charts are displayed in real-time with responses to market ticks being shown in real-time (updating one to two times per second is probably a reasonable display refresh policy). We've been looking for a software package (commercial is fine by us) that has the capability of displaying these charts. Additionally, we'd like to have an approach that can render the initial amount of data in a reasonable timeframe (give or take 100-200ms from the time we hand the data over to a complete render on screen). Also we view multiple charts (5-10) simultaneously so a solution that chews up 50% of my CPU to display one chart really isn't going to work well. Has anyone had any good experiences with charting controls. We've had to hand roll the last few charts we've done and I'd prefer not to do it again. Solutions that can make use of the GPU to minimize CPU utilization would be nice as well.

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  • populate jsp drop down with database info

    - by Cano63
    Hello, people, i,m looking for the way to populate a jsp dropdown. I want that when the jsp load it fill the dropdown with the info that i have in a database table. Down I,m icluding the code of my class that will create the array and fill it with the database info. Whant i don,t know is how to call that class from my jsp and fill the dropdown. '// this will create my array public static ArrayList getBrandsMakes() { ArrayList arrayBrandsMake = new ArrayList(); while(rs.next()) { arrayBrandsMake.add(loadOB(rs)); // CARGO MI ARREGLO CON UN OBJETO } return arrayBrandsMake; } } //this will load my array object private static DropDownBrands loadOB(ResultSet rs)throws SQLException { DropDownBrands OB = new DropDownBrands (); OB.setBrands("BRAN"); return OB; } '

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  • Adding MySQL servers/ data nodes into database clustering without restarting mysql cluster

    - by Dwayne Johnson
    I currently have mysql clustering up and running. For high scalability is there a way to include either mysql node, data nodes, or management nodes without restarting the entire cluster. I wish to understand how is it implement or is there a documentation I can read. I believe only the latest version can support this. I am running NDB 7.0. I am aware that I am able to add the nodes online, but it requires me perform a rolling restart. What other approach I can take to implement this without restarting in my network?

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  • Indexing vs. no indexing when inserting records

    - by jbu
    I have a few questions about whether or not it would be best to not use indexing. BACKGROUND: My records have a timestamp attribute, and the records will be inserted in order of their timestamps (i.e., inserted chronologically). QUESTIONS: If I DON'T use indexing is it typical for the database to insert the records in the order that they were inserted? If answer to #1 is yes, when I do a "SELECT .. WHERE timestamp X" type query will the database be efficient at it, or will it have to go through every single record since it isn't indexed? I would assume if there were no index, the database would not "know" that the records were inserted in sorted order and could not, therefore, make use of sorted property of the database. I assume a clustered index would be best for these types of records & their inserts. Please let me know what you guys think. Thanks, jbu

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  • Where is the handy designer for setting Permissions and schema diagram designer in a SQL2005 Databas

    - by BlackMael
    I have just installed the GDR RTM version of Visual Studio Team System Database Edition GDR RTM. It all seems to work wonderfully, but I seem to have to edit XML (Database.sqlpermissions) for specify SQL Permissions. Am I missing something? For that matter where is the schema diagram tool? I understand GDR exposes alot for extending the Database Edition components, so am I supposed to wait for third party extensions to provide the diagram tool and permissions designer?

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  • Asynchronous operations performance

    - by LicenseQ
    One of the features of asynchronous programming in .NET is saving threads during long running operation execution. The FileStream class can be setup to allow asynchronous operations, that allows running (e.g.) a copy operation without virtually using any threads. To my surprise, I found that running asynchronous stream copy performs not only slower, but also uses more processing power than synchronous stream copy equivalent. Is there any benchmark tests were done to compare a synchronous vs asynchronous operation execution (file, network, etc.)? Does it really make sense to perform an asynchronous operation instead of spanning separate thread and perform synchronous operation in server environment if the asynchronous operation is times slower than the synchronous one?

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  • Repository pattern - Switch out the database and switch in XML files

    - by glasto red
    Repository pattern - Switch out the database and switch in XML files. Hello I have an asp.net MVC 2.0 project and I have followed the Repository pattern. Periodically, I am losing access to the database server so I want to have another mechanism in place (XML files) to continue developing. It is not possible to have a local version of the db unfortunately! I thought this would be relatively easy using the Repository pattern, to switch out the db repositories and switch in XML versions. However, I am having real trouble coming up with a solution. I have tried LinqToXML but then ran into problems trying to return a List of News items as the LinqToXML ToList returns Generic.List Should I be mapping the XElement list over to the News list by hand? It just seems a bit clunky compared to LinqToSQL attributes on the News class and then simply doing a Table.....ToList(); Any direction would be appreciated. Thanks

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  • Importing a large dataset into a database

    - by peaceful
    I'm a beginning programmer in the relevant areas to this question, so if possible, it'd be helpful to avoid assuming I know a lot already. I'm trying to import the OpenLibrary dataset into a local Postgres database. After it's imported, I plan to use it as a starting seed for a Ruby on Rails application that will include information on books. The OpenLibrary datasets are available here, in a modified JSON format: http://openlibrary.org/dev/docs/jsondump I only need very basic information for my application, much less than what is provided in the dumps. I'm only trying to get out book titles, author names, and relationships between books and authors. Below are two typical entries from their dataset, the first for an author, and the second for a book (they seem to have an entry for each edition of a book). The entries seem to lead off with a primary key, and then with a type, before including the actual JSON database dump. /a/OL2A /type/author {"name": "U. Venkatakrishna Rao", "personal_name": "U. Venkatakrishna Rao", "last_modified": {"type": "/type/datetime", "value": "2008-09-10 08:44:01.978456"}, "key": "/a/OL2A", "birth_date": "1904", "type": {"key": "/type/author"}, "id": 99, "revision": 3} /b/OL345M /type/edition {"publishers": ["Social Science Research Project, Dept. of Geography, University of Dacca"], "pagination": "ii, 54 p.", "title": "Land use in Fayadabad area", "lccn": ["sa 65000491"], "subject_place": ["East Pakistan", "Dacca region."], "number_of_pages": 54, "languages": [{"comment": "initial import", "code": "eng", "name": "English", "key": "/l/eng"}], "lc_classifications": ["S471.P162 E23"], "publish_date": "1963", "publish_country": "pk ", "key": "/b/OL345M", "authors": [{"birth_date": "1911", "name": "Nafis Ahmad", "key": "/a/OL302A", "personal_name": "Nafis Ahmad"}], "publish_places": ["Dacca, East Pakistan"], "by_statement": "[by] Nafis Ahmad and F. Karim Khan.", "oclc_numbers": ["4671066"], "contributions": ["Khan, Fazle Karim, joint author."], "subjects": ["Land use -- East Pakistan -- Dacca region."]} The size of the uncompressed dumps are enormous, about 2GB for the authors list, and 18GB for the book editions list. OpenLibrary does not provide any tools for this themselves, they provide a simple unoptimized Python script for reading in sample data (which unlike the actual dumps comes in pure JSON format), but they estimate if that was modified for use on their actual data it would take 2 months (!) to finish loading the data. How can I read this into the database? I assume I'll need to write a program to do this. What language and any guidance on how I should do it to finish in a reasonable amount of time? The only scripting language I have any experience with is Ruby.

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  • Does Multiple NSURLConnection make delay of performance?

    - by oksk
    Hi all~. I made a multi files downloader. I implemented NSURLConnection using NSOperationQueue. NSOpetationQueue has many NSURLConnection operations. and, set MaxConcurrentOperationCount to 10. I thought my code is right, But after run the project, it was wrong. there are some connection error has occured. files url were right. and file download was completed. but downloading files, occur "timed out" error. It is so serious. I tested it with 8 files, and those total size is only 3M. But total download time is 2minutes ~!!! one file download spends only a few second. (2~3 s) but multi files download occur many overburden!! (2 minutes) I don't know why it is... Do Anyone know what reason is?

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