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• My OpenCL kernel is slower on faster hardware.. But why?

  - by matdumsa

  Hi folks, As I was finishing coding my project for a multicore programming class I came up upon something really weird I wanted to discuss with you. We were asked to create any program that would show significant improvement in being programmed for a multi-core platform. I’ve decided to try and code something on the GPU to try out OpenCL. I’ve chosen the matrix convolution problem since I’m quite familiar with it (I’ve parallelized it before with open_mpi with great speedup for large images). So here it is, I select a large GIF file (2.5 MB) [2816X2112] and I run the sequential version (original code) and I get an average of 15.3 seconds. I then run the new OpenCL version I just wrote on my MBP integrated GeForce 9400M and I get timings of 1.26s in average.. So far so good, it’s a speedup of 12X!! But now I go in my energy saver panel to turn on the “Graphic Performance Mode” That mode turns off the GeForce 9400M and turns on the Geforce 9600M GT my system has. Apple says this card is twice as fast as the integrated one. Guess what, my timing using the kick-ass graphic card are 3.2 seconds in average… My 9600M GT seems to be more than two times slower than the 9400M.. For those of you that are OpenCL inclined, I copy all data to remote buffers before starting, so the actual computation doesn’t require roundtrip to main ram. Also, I let OpenCL determine the optimal local-worksize as I’ve read they’ve done a pretty good implementation at figuring that parameter out.. Anyone has a clue? edit: full source code with makefiles here http://www.mathieusavard.info/convolution.zip cd gimage make cd ../clconvolute make put a large input.gif in clconvolute and run it to see results

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• Silverlight 4 seems like starving of memory

  - by Marco

  I have been playing a bit with Silverlight and try to port my Silverlight 3.0 application to Silverlight 4.0. My application loads different XAP files and upon a user request create an instance of a Xaml user control and adds it to the main container, in a sort of MEF approach in order I can have an extensible and pluggable application. The application is pretty huge and to keep acceptable the performances and the initial loading I have built up some helper classes to load in the background all pages and user controls that might be used later on. On Silverlight 3.0 everything was running smoothly without any problem so far. Switching to SL 4.0 I have noticed that when the process approaches to create the instances of the user controls the layout freezes unexpectedly for a minute and sometimes for more. Looking at the task manager the memory usage of IE jumps from 50MB to 400MB and sometimes up to 1.5 GB. If the process won't take that much the layout is rendered properly even though the memory usage is still extremely high. Otherwise everything crashes due to out of memory exception. Running the same application compiled in SL3, the memory used is about 200MB when all the usercontrols are loaded. Time spent to load the application in SL3 is about 10 seconds, while it takes up to 3 mins in SL4 There are no transparencies, no opacities set, no effects and animations in the layout. User controls are instantied on the fly and added or removed in the visual tree on purpose when the user switches from one screen to another. The resources are all cleaned properly when a usercontrol is removed from the visual tree to allow the GC to operate in the background. I may do something wrong but I could not figure out where exactly nail out the source of this problem. As far as I know there is no memory profiler in SL4 that can help me out to find where to look at. But again I could not be updated on new debugging tools available.

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• Design: Website calling a webservice on the same machine

  - by Chris L

  More of a design/conceptual question. At work the decision was made to have our data access layer be called through webservices. So our website would call the webservices for any/all data to and from the database. Both the website & the webservices will be on the same machine(so no trip across the wire), but the database is on a separate machine(so that would require a trip across the wire regardless). This is all in-house, the website, webservice, and database are all within the same company(AFAIK, the webservices won't be reused by another other party). To the best of my knowledge: the website will open a port to the webservices, and the webservices will in turn open another port and go across the wire to the database server to get/submit the data. The trip across the wire can't be avoided, but I'm concerned about the webservices standing in the middle. I do agree there needs to be distinct layers between the functionality(such as business layer, data access layer, etc...), but this seems overly complex to me. I'm also sensing there will be some performance problems down the line. Seems to me it would be better to have the (DAL)assemblies referenced directly within the solution, thus negating the first port to port connection. Any thoughts(or links) both for and against this idea would be appreciated P.S. We're a .NET shop(migrating from vb to C# 3.5)

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• Delphi 2009 dbExpress and Interbase: Unicode migration steps and risks?

  - by mjustin

  Currently, our database uses Win1252 as the only character encoding. We will have to support Unicode in the database tables soon, which means we have to perform this migration for four databases and around 80 Delphi applications which run in-house in a 24/7 environment. Are there recommendations for database migrations to UTF-8 (or UNICODE_FSS) for Delphi applications? Some questions listed below. Many thanks in advance for your answers! are there tools which help with the migration of the existing databases (sizes between 250 MB and 2 GB, no Blob fields), by dumping the data, recreating the database with UNICODE_FSS or UTF-8, and loading the data back? are there known problems with Delphi 2009, dbExpress and Interbase 7.5 related to Unicode character sets? would you recommend to upgrade the databases to Interbase 2009 first? (This upgrade is planned but does not have a high priority) can we simply migrate the database and Delphi will handle the Unicode character sets automatically, or will we have to change all character field types in every Datamodule (dfm and source code) too? which strategy would you recommend to work on the migration in parallel with the normal development and maintenance of the existing application? The application runs in-house so development and database administration is done internally. Update: one problem I found now is that there are two different persistent field types for Unicode and non Unicode character fields. For the existing database, dbExpress creates TStringField objects. For the Unicode database fields, dbExpress creates (or expects!) TWideStringField objects. This looks like a lot of work lies ahead. While we could try to avoid persistent fields (and add calculated fields at run time), Of course we would prefer a solution which does not require so many changes in existing units and DFM files.

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• Problem with Binding Multiple Objects on WPF

  - by Diego Modolo Ribeiro

  Hi, I'm developing a user control called SearchBox, that will act as a replacer for ComboBox for multiple records, as the performance in ComboBox is low for this scenario, but I'm having a big binding problem. I have a base control with a DependencyProperty called SelectedItem, and my SearchControl shows that control so that the user can select the record. The SearchControl also has a DependencyProperty called SelectedItem on it, and it is being updated when the user selects something on the base control, but the UI, wich has the SearchControl, is not being updated. I used a null converter so that I could see if the property was updating, but it's not. Below is some of the code: This is the UI: <NectarControles:MaskedSearchControl x:Name="teste" Grid.Row="0" Grid.Column="1" Height="21" ItemsSource="{Binding C001_Lista}" DisplayMember="C001_Codigo" Custom:CustomizadorTextBox.CodigoCampo="C001_Codigo" ViewType="{x:Type C001:C001_Search}" ViewModelType="{x:Type C001_ViewModel:C001_ViewModel}" SelectedItem="{Binding Path=Instancia.C001_Holding, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged, Converter={StaticResource DebuggingConverter}}"> </NectarControles:MaskedSearchControl> This is the relevante part of the SearchControl: Binding selectedItemBinding = new Binding("SelectedItem"); selectedItemBinding.Source = this.SearchControlBase; selectedItemBinding.Mode = BindingMode.TwoWay; selectedItemBinding.UpdateSourceTrigger = UpdateSourceTrigger.PropertyChanged; this.SetBinding(SelectedItemProperty, selectedItemBinding); ... public System.Data.Objects.DataClasses.IEntityWithKey SelectedItem { get { return (System.Data.Objects.DataClasses.IEntityWithKey)GetValue(SelectedItemProperty); } set { SetValue(SelectedItemProperty, value); if (PropertyChanged != null) PropertyChanged(this, new PropertyChangedEventArgs("SelectedItem")); } } Please someone help me... Tks...

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• Is Annotation in Javascript? If not, how to switch between debug/productive modes in declarative way

  - by Michael Mao

  Hi all: This is but a curious question. I cannot find any useful links from Google so it might be better to ask the gurus here. The point is: is there a way to make "annotation" in javascript source code so that all code snippets for testing purpose can be 'filtered out' when project is deployed from test field into the real environment? I know in Java, C# or some other languages, you can assign an annotation just above the function name, such as : // it is good to remove the annoying warning messages @SuppressWarnings("unchecked") public class Tester extends TestingPackage { ... } Basically I've got a lot of testing code that prints out something into FireBug console. I don't wanna manually "comment out" them because the guy that is going to maintain the code might not be aware of all the testing functions, so he/she might just miss one function and the whole thing can be brought down to its knees. One other thing, we might use a minimizer to "shrink" the source code into "human unreadable" code and boost up performance (just like jQuery.min), so trying to match testing section out of the mess is not possible for plain human eyes in the future. Any suggestion is much appreciated.

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• Registry access error when Migrating ASP.NET application to IIS7

  - by fande455

  I'm running windows 7 64-bit and iis7. I'm trying to setup a web application that was previously in iis6 on XP. It's giving me the error below. I've added the network service user to the Performance Monitor Users group to no avail. Access to the registry key 'Global' is denied. Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code. Exception Details: System.UnauthorizedAccessException: Access to the registry key 'Global' is denied. ASP.NET is not authorized to access the requested resource. Consider granting access rights to the resource to the ASP.NET request identity. ASP.NET has a base process identity (typically {MACHINE}\ASPNET on IIS 5 or Network Service on IIS 6) that is used if the application is not impersonating. If the application is impersonating via , the identity will be the anonymous user (typically IUSR_MACHINENAME) or the authenticated request user. To grant ASP.NET access to a file, right-click the file in Explorer, choose "Properties" and select the Security tab. Click "Add" to add the appropriate user or group. Highlight the ASP.NET account, and check the boxes for the desired access.

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• Strategies for serializing an object for auditing/logging purpose in .NET?

  - by Jiho Han

  Let's say I have an application that processes messages. Messages are just objects in this case that implements IMessage interface which is just a marker. In this app, if a message fails to process, then I want to log it, first of all for auditing and troubleshooting purposes. Secondly I might want to use it for re-processing. Ideally, I want the message to be serialized into a format that is human-readable. The first candidate is XML although there are others like JSON. If I were to serialize the messages as XML, I want to know whether the message object is XML-serializable. One way is to reflect on the type and to see if it has a parameter-less constructor and the other is to require IXmlSerializable interface. I'm not too happy with either of these approaches. There is a third option which is to try to serialize it and catch exceptions. This doesn't really help - I want to, in some way, stipulate that IMessage (or a derived type) should be xml-serializable. The reflection route has obvious disadvantages such as security, performance, etc. IXmlSerializable route locks down my messages to one format, when in the future, I might want to change the serialization format to be JSON. The other thing is even the simplest objects now must implement ReadXml and WriteXml methods. Is there a route that involves the least amount of work that lets me serialize an arbitrary object (as long as it implements the marker interface) into XML but not lock future messages into XML?

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• Best approach to storing image pixels in bottom-up order in Java

  - by finnw

  I have an array of bytes representing an image in Windows BMP format and I would like my library to present it to the Java application as a BufferedImage, without copying the pixel data. The main problem is that all implementations of Raster in the JDK store image pixels in top-down, left-to-right order whereas BMP pixel data is stored bottom-up, left-to-right. If this is not compensated for, the resulting image will be flipped vertically. The most obvious "solution" is to set the SampleModel's scanlineStride property to a negative value and change the band offsets (or the DataBuffer's array offset) to point to the top-left pixel, i.e. the first pixel of the last line in the array. Unfortunately this does not work because all of the SampleModel constructors throw an exception if given a negative scanlineStride argument. I am currently working around it by forcing the scanlineStride field to a negative value using reflection, but I would like to do it in a cleaner and more portable way if possible. e.g. is there another way to fool the Raster or SampleModel into arranging the pixels in bottom-up order but without breaking encapsulation? Or is there a library somewhere that will wrap the Raster and SampleModel, presenting the pixel rows in reverse order? I would prefer to avoid the following approaches: Copying the whole image (for performance reasons. The code must process hundreds of large (= 1Mpixels) images per second and although the whole image must be available to the application, it will normally access only a tiny (but hard-to-predict) portion of the image.) Modifying the DataBuffer to perform coordinate transformation (this actually works but is another "dirty" solution because the buffer should not need to know about the scanline/pixel layout.) Re-implementing the Raster and/or SampleModel interfaces from scratch (but I have a hunch that I will be unable to avoid this.)

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• Writing a JMS Publisher without "public static void main"

  - by The Elite Gentleman

  Hi guys, Every example I've seen on the web, e.g. http://www.codeproject.com/KB/docview/jms_to_jms_bridge_activem.aspx, creates a publisher and subscriber with a public static void main method. I don't think that'll work for my web application. I'm learning JMS and I've setup Apache ActiveMQ to run on JBoss 5 and Tomcat 6 (with no glitches). I'm writing a messaging JMS service that needs to send email asynchronously. I've already written a JMS subscriber that receives the message (the class inherits MessageListener). My question is simple: How do I write a publisher that will so that my web applications can call it? Does it have to be published somewhere? My thought is to create a publisher with a no-attribute constructor (in there) and get the MessageQueue Factory, etc. from the JNDI pool (in the constructor). Is my idea correct? How do I subscribe my subscriber to the Queue Receiver? (So far, the subscriber has no constructor, and if I write a constructor, do I always subscribe myself to the Queue receiver?) Thanks for your help, sorry if my terminology is not up to scratch, there are too many java terminologies that I get lost sometimes (maybe a java GPS will do! :-) ) PS Is there a tutorial out there that explains how to write a "better" (better can mean anything, but in my case it's all about performance in high demand requests) JMS Publisher and Subscriber that I can run on Application Server such as JBoss or Glassfish? Don't forget that the JMS application will needs a "guarantee" uptime as many applications will use this.

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• Automatically install and launch a code-signed application from Safari

  - by Thomas Jung

  Is it possible and if so what are the steps necessary to package (or build) a Mac OS X application and code-sign it so that it can be downloaded with Safari and automatically launch? ... possibly after the user responds to some sort of dialog explaining that it is a signed application and the publisher has been verified. An example of the user experience I am trying to create is "installing Google Chrome for the first time on Windows", which is a 3-click, less-than-a-minute process. For the concerned among you: I am not trying to create a drive-by download. I am fine with some sort of intermittent user step approving the download. I just want to make the installation as quick and painless as possible and not require the user drag the app from a mounted DMG into the application folder. This may not 100% jibe with established Mac OS X user interaction guidelines, but it would work better for the not-power users. I only need the high-level steps or pointers to resources ... my google-fu was weak on this one.

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• Rails : fighting long http response times with ajax. Is it a good idea? Please, help with implementa

  - by baranov

  Hi, everybody! I've googled some tutorials, browsed some SO answers, and was unable to find a recipe for my problem. I'm writing a web site which is supposed to display almost realtime stock chart. Data is stored in constantly updating MySQL database, I wrote a find_by_sql query code which fetches all the data I need to get my chart drawn. Everything is ok, except performance - it takes from one second to one minute for different queries to fetch all the data from the database, this time includes necessary (My)SQL-server side calculations. This is simply unacceptable. I got the following idea: if the data is queried from the MySQL server one point a time instead of entire dataset, it takes only about 1-100ms to get an individual point. I imagine the data fetch process might be browser-driven. After the user presses the button in order to get a chart drawn, controller makes one request to the database and renders, say, a progress bar, say 1% ready. When the browser gets the response, it immediately makes an (ajax) request, and the server fetches the next piece of data and renders "2%". And so on, until all the data is ready and the server displays the requested chart. Could this be implemented in rails+js, is there a tutorial for solving a similar problem on the Web? I suppose if the thing is feasible at all, somebody should have already done this before. I have read several articles about ajax, I believe I do understand general principles, but never did nontrivial ajax programming myself. Thanks for your time!

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• Why can't I create a database in an empty ASP MVC 2 project using Project->Add->New Item->SQL Server

  - by Dr Dork

  I'm diving head first into ASP MVC and am playing around with creating and manipulating a database. I did a search and found this tutorial for creating a database, however when I follow it, I get this error when trying to add a new database to my fresh, empty ASP MVC 2 project... A network-related or instance-specific error occurred while establishing a connection to SQL Server. The server was not found or was not accessible. Verify that the instance name is correct and that SQL Server is configured to allow remote connections. (provider: SQL Network Interfaces, error: 26 - Error Locating Server/Instance Specified) The only requirement the tutorial mentioned was SQL Server Express, but when I went to download it, it said it was already installed. I'm assuming it was part of the VS 2010 RC I installed and am running. So I don't know what else I need if I am missing something. This is all new to me, so I'm sure I'm missing something obvious here and after I'm done posting this question, I plan to do some more research into the topic of databases and how they work with ASP MVC. In the meantime, I was you could help me answer a couple high level questions... What am I missing/forgetting to do that is causing this error? Any suggestions for good resources/tutorials that focus on using databases with ASP MVC? I've done a lot of database programming in the past, so I'm familiar with the concepts of relational databases and the SQL language. I wish I could find a good resource for learning how to work with them in an ASP dev environment, as well as a good breakdown of all the related technologies used for working with them (i.e. LINQ to SQL). Thanks so much in advance for all your help! I'm going to start researching these questions right now.

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• Does Firefox on OS X Lion make use of Full Page Zoom for the touchpad? How to customize behavior?

  - by Steven Lu

  I really like the smooth pinch-zoom of Safari using the touchpad, but the two-finger scroll on Firefox is so much better than the scrolling performance in Safari. So I really like to use Firefox, but then I miss out on two-finger-double-tap to zoom to paragraph width, and the smooth pinch gesture zoom. What I'm wondering is if it is possible to write a Firefox Extension to improve the update rate of the full-page zoom in Firefox that is already functioning via the touchpad pinch gesture. I feel like it is specifically programmed to zoom at certain zoom levels: 100%, 120%, 150% (these are guesses of mine) but I think it would be great if I can get some more control there to make it work more like the zoom functionality in Safari. Also the two-finger-double-tap on a paragraph or element to zoom to it would be really awesome as well. https://developer.mozilla.org/en/Full_page_zoom This seems to indicate (if "full page zoom" is what I think it is) that an extension has the ability to zoom to an arbitrary scale factor, but what remains is to find out if it is possible to obtain or hook the touchpad pinch gesture. Update: I have updated the toolkit.zoomManager.zoomValues option in about:config to include more zoom levels: .3,.5,.67,.8,.9,1,1.01,1.02,1.03,1.04,1.05,1.06,1.07,1.08,1.09,1.1,1.2,1.33,1.5,1.7,2,2.4,3 Notice how I inserted a bunch of entries between 1 and 1.1. But it isn't switching between them any faster (why would it?) so it's less usable than before because of waiting for it to respond fast enough. It's clear that re-rendering the page at a different zoom level requires time and in order for the zoom to be dynamic, some kind of screen capture and scale effect must be performed (which is what Safari does). I guess such a thing is probably doable but I don't think I could pull it off. :-/

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• Algorithm to determine which points should be visible on a map based on zoom

  - by lgratian

  Hi! I'm making a Google Maps-like application for a course at my Uni (not something complex, it should load the map of a city for example, not the whole world). The map can have many layers, including markers (restaurants, hospitals, etc.) The problem is that when you have many points and you zoom out the map it doesn't look right. At this zoom level only some points need to be visible (and at the maximum map size, all points). The question is: how can you determine which points should be visible for a specified zoom level? Because I have implemented a PR Quadtree to speed up rendering I thought that I could define some "high-priority" markers (that are always visible, defined in the map editor) and put them in a queue. At each step a marker is removed from the queue and all it's neighbors that are at least D units away (D depends on the zoom levels) are chosen and inserted in the queue, and so on. Is there any better way than the algorithm I thought of? Thanks in advance!

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• iPhone OpenGL and NSTimer issues

  - by Kyle

  I have an NSTimer that runs at 60hz. With an OpenGL scene loaded and rendering, my game can get 60fps, solid, all day long.. Then if I go and recompile the app, or reload it, it will get 40fps. Same resources loaded. I've been running into this problem for years, and I just want to know why. It's crazy, and I want to know if I should just abandon this stupid Timer. Conditions are not different on my 3GS between loads. It will just get 40fps sometimes. Obviously the clockrate is not different between loads, so the performance figures should be constant given a constant scene. Here is a log of my framerates: A good load: :-) FrameRate: 61 FrameRate: 61 FrameRate: 61 FrameRate: 60 FrameRate: 60 FrameRate: 61 FrameRate: 60 FrameRate: 60 FrameRate: 61 FrameRate: 60 FrameRate: 61 Now, I'll go ahead and do nothing, recompile, and run: FrameRate: 43 FrameRate: 50 FrameRate: 45 FrameRate: 48 FrameRate: 40 FrameRate: 45 FrameRate: 42 FrameRate: 41 FrameRate: 42 FrameRate: 44 FrameRate: 41 FrameRate: 46 ^- Massive difference visually. What the flying heck could cause this? SAME area of the scene, SAME camera setup. No variables are different.

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• DNS-Based Environment Determination

  - by zvolkov

  Found the following here. The questions is: where can I find more details on how exactly implement this on Windows? Any guide or how-to anybody? Or maybe you can provide your invaluable suggestions? Specifically, how do I make so that "all QA servers would first resolve entries in qa.example.com first and then if that lookup failed they would try example.com" (I'm a dev, not a DNS specialist, but our IT Support has refused to help on this:() Use DNS Based Environment Determination for your servers. Do this by initially splitting your top level domain into a number of sub domains depending on their function, and then creating DNS Service Names in each of the sub domains pointing to the relevant server for that service. Based on the list above we would then have: * clientdb.prod.example.com for Production * clientdb.perf.example.com for Performance Testing * clientdb.qa.example.com for QA * clientdb.dev.example.com for Development Servers then resolve entries in their relevant sub domain by function. That is, all QA servers would first resolve entries in qa.example.com first and then if that lookup failed they would try example.com. This allows you to have a single configuration entry for your client database hostname (clientdb) that would resolve correctly in all environments. This technique has the added advantage of still having global services defined in a common top level domain. Here's one related (but not equivalent) SO question: http://stackoverflow.com/questions/774490/dns-resolving-based-on-client-ip This seems to be related to Providing "split horizon" DNS service. Reading that, I see that I will probably need separate DNS Server for each environment. Is this true or does Windows support some form of "tagging" the records to be visible depending on the requestor's IP? Also, cross-posted on ServerFault

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• Best practices for Java logging from multiple threads?

  - by Jason S

  I want to have a diagnostic log that is produced by several tasks managing data. These tasks may be in multiple threads. Each task needs to write an element (possibly with subelements) to the log; get in and get out quickly. If this were a single-task situation I'd use XMLStreamWriter as it seems like the best match for simplicity/functionality without having to hold a ballooning XML document in memory. But it's not a single-task situation, and I'm not sure how to best make sure this is "threadsafe", where "threadsafe" in this application means that each log element should be written to the log correctly and serially (one after the other and not interleaved in any way). Any suggestions? I have a vague intuition that the way to go is to use a queue of log elements (with each one able to be produced quickly: my application is busy doing real work that's performance-sensitive), and have a separate thread which handles the log elements and sends them to a file so the logging doesn't interrupt the producers. The logging doesn't necessarily have to be XML, but I do want it to be structured and machine-readable. edit: I put "threadsafe" in quotes. Log4j seems to be the obvious choice (new to me but old to the community), why reinvent the wheel...

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• Mysqli query only works on localhost, not webserver

  - by whamo

  Hello. I have changed some of my old queries to the Mysqli framework to improve performance. Everything works fine on localhost but when i upload it to the webserver it outputs nothing. After connecting I check for errors and there are none. I also checked the php modules installed and mysqli is enabled. I am certain that it creates a connection to the database as no errors are displayed. (when i changed the database name string it gave the error) There is no output from the query on the webserver, which looks like this: $mysqli = new mysqli("server", "user", "password"); if (mysqli_connect_errno()) { printf("Can't connect Errorcode: %s\n", mysqli_connect_error()); exit; } // Query used $query = "SELECT name FROM users WHERE id = ?"; if ($stmt = $mysqli->prepare("$query")) { // Specify parameters to replace '?' $stmt->bind_param("d", $id); $stmt->execute(); // bind variables to prepared statement $stmt->bind_result($_userName); while ($stmt->fetch()) { echo $_userName; } $stmt-close(); } } //close connection $mysqli-close(); As I said this code works perfectly on my localserver just not online. Checked the error logs and there is nothing so everything points to a good connection. All the tables exists as well etc. Anyone any ideas because this one has me stuck! Also, if i get this working, will all my other queries still work? Or will i need to make them use the mysqli framework as well? Thanks in advance.

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• Which non-clustered index should I use?

  - by Junior Mayhé

  Here I am studying nonclustered indexes on SQL Server Management Studio. I've created a table with more than 1 million records. This table has a primary key. CREATE TABLE [dbo].[Customers]( [CustomerId] [int] IDENTITY(1,1) NOT NULL, [CustomerName] [varchar](100) NOT NULL, [Deleted] [bit] NOT NULL, [Active] [bit] NOT NULL, CONSTRAINT [PK_Customers] PRIMARY KEY CLUSTERED ( [CustomerId] ASC )WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY] ) ON [PRIMARY] This is the query I'll be using to see what execution plan is showing: SELECT CustomerName FROM Customers Well, executing this command with no additional non-clustered index, it leads the execution plan to show me: I/O cost = 3.45646 Operator cost = 4.57715 Now I'm trying to see if it's possible to improve performance, so I've created a non-clustered index for this table: 1) First non-clustered index CREATE NONCLUSTERED INDEX [IX_CustomerID_CustomerName] ON [dbo].[Customers] ( [CustomerId] ASC, [CustomerName] ASC )WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, SORT_IN_TEMPDB = OFF, IGNORE_DUP_KEY = OFF, DROP_EXISTING = OFF, ONLINE = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY] GO Executing again the select against Customers table, the execution plan shows me: I/O cost = 2.79942 Operator cost = 3.92001 It seems better. Now I've deleted this just created non-clustered index, in order to create a new one: 2) First non-clustered index CREATE NONCLUSTERED INDEX [IX_CustomerIDIncludeCustomerName] ON [dbo].[Customers] ( [CustomerId] ASC ) INCLUDE ( [CustomerName]) WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, SORT_IN_TEMPDB = OFF, IGNORE_DUP_KEY = OFF, DROP_EXISTING = OFF, ONLINE = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY] GO With this new non-clustered index, I've executed the select statement again and the execution plan shows me the same result: I/O cost = 2.79942 Operator cost = 3.92001 So, which non-clustered index should I use? Why the costs are the same on execution plan for I/O and Operator? Am I doing something wrong or this is expected? thank you

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• java time check API

  - by ring bearer

  I am sure this was done 1000 times in 1000 different places. The question is I want to know if there is a better/standard/faster way to check if current "time" is between two time values given in hh:mm:ss format. For example, my big business logic should not run between 18:00:00 and 18:30:00. So here is what I had in mind: public static boolean isCurrentTimeBetween(String starthhmmss, String endhhmmss) throws ParseException{ DateFormat hhmmssFormat = new SimpleDateFormat("yyyyMMddhh:mm:ss"); Date now = new Date(); String yyyMMdd = hhmmssFormat.format(now).substring(0, 8); return(hhmmssFormat.parse(yyyMMdd+starthhmmss).before(now) && hhmmssFormat.parse(yyyMMdd+endhhmmss).after(now)); } Example test case: String doNotRunBetween="18:00:00,18:30:00";//read from props file String[] hhmmss = downTime.split(","); if(isCurrentTimeBetween(hhmmss[0], hhmmss[1])){ System.out.println("NOT OK TO RUN"); }else{ System.out.println("OK TO RUN"); } What I am looking for is code that is better in performance in looks in correctness What I am not looking for third-party libraries Exception handling debate variable naming conventions method modifier issues

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• how to push different local git branches to heroku/master

  - by lsiden

  Heroku has a policy of ignoring all branches but 'master'. While I'm sure Heroku's designers have excellent reasons for for this policy (I'm guessing for storage and performance optimization), the consequence to me as a developer is that whatever local topic branch I may be working on, I would like an easy way to switch Heroku's master to that local topic branch and do a "git push heroku -f" to over-write master on Heroku. What I got from reading the "Pushing Refspecs" section of http://progit.org/book/ch9-5.html is git push -f heroku local-topic-branch:refs/heads/master What I'd really like is a way to set this up in the config file so that "git push heroku" always does the above, replacing local-topic-branch with the name of whatever my current branch happens to be. If anyone knows how to accomplish that, please let me know! The caveat for this, of course, is that this is only sensible if I am the only one who can push to that Heroku app/repository. A test or QA team might manage such a repository to try out different candidate branches, but they would have to coordinate so that they all agree on what branch they are pushing to it on any given day. Needless to say, it would also be a very good idea to have a separate remote repository (like Github) without this restriction for backing everything up to. I'd call that one "origin" and use "heroku" for Heroku so that "git push" always backs up everything to origin, and "git push heroku" pushes whatever branch I'm currently on to Heroku's master branch, overwriting it if necessary. Can anybody tell me if this would work? [remote "heroku"] url = [email protected]:my-app.git push = +refs/heads/*:refs/heads/master I'd like to hear from someone more experienced before I begin to experiment, although I suppose I could create a dummy app on Heroku and experiment with that. As for fetching, I don't really care if the Heroku repository is write-only. I still have a separate repository, like Github, for backup and cloning of all my work. Footnote: This question is similar to, but not quite the same as http://stackoverflow.com/questions/1489393/good-git-deployment-using-branches-strategy-with-heroku

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• Neural Network settings for fast training

  - by danpalmer

  I am creating a tool for predicting the time and cost of software projects based on past data. The tool uses a neural network to do this and so far, the results are promising, but I think I can do a lot more optimisation just by changing the properties of the network. There don't seem to be any rules or even many best-practices when it comes to these settings so if anyone with experience could help me I would greatly appreciate it. The input data is made up of a series of integers that could go up as high as the user wants to go, but most will be under 100,000 I would have thought. Some will be as low as 1. They are details like number of people on a project and the cost of a project, as well as details about database entities and use cases. There are 10 inputs in total and 2 outputs (the time and cost). I am using Resilient Propagation to train the network. Currently it has: 10 input nodes, 1 hidden layer with 5 nodes and 2 output nodes. I am training to get under a 5% error rate. The algorithm must run on a webserver so I have put in a measure to stop training when it looks like it isn't going anywhere. This is set to 10,000 training iterations. Currently, when I try to train it with some data that is a bit varied, but well within the limits of what we expect users to put into it, it takes a long time to train, hitting the 10,000 iteration limit over and over again. This is the first time I have used a neural network and I don't really know what to expect. If you could give me some hints on what sort of settings I should be using for the network and for the iteration limit I would greatly appreciate it. Thank you!

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• rapid application developement tools for very basic GUI apps

  - by Jurij

  I know there are many RAD platforms out there. Infact there are so many that I'm having a hard time finding out which one fits me best. What I want is a RAD tool that would allow me to define a database data model (make DB tables) and then create (view and edit) forms for the various tables. Data input, updating and various queries should be easy and GUI should generate automatically. I'd like to add some additional functionality by coding (such as various complex calculations on the data). I'm a programmer so I'm willing to learn to use a more complete, full-blown RAD solution if you can point me to it (NetBeans and RubyOnRails being the two such frameworks that I'd would probably be high on the list). I'm currently doing Windows Forms logistics apps in .NET. I've actually developed a very crude and basic version of what I need, but I just know that there are solutions out there that are much better and I'd benefit by knowing how to use them. So in short, the basic requirements: * database based data storage (SQLite if possible) * very automated GUI creation * desktop based (as in: not a web app) * extendable by coding * used for creating simple data entry, view & query apps. So basically something like Oracle Forms or DotNetMushroom Rapid Application Developer. But for .NET and SQLite if possible.

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• Self-referencing tables in Linq2Sql

  - by J-Man

  Hi, I've seen a lot of questions on self-referencing tables in Linq2Sql and how to eagerly load all child records for a particular root object. I've implemented a temporary solution by accessing all underlying properties, but you can see that this doesn't do the performance any good. The thing is though, that all records are correlated with each-other using a correlation GUID. Example below: RootElement - Id: 1 - ParentId: null - CorrelationId: 4D68E512-4B55-44f4-BA5A-174B630A03DD ChildElement1 - Id: 2 - ParentId: 1 - CorrelationId: 4D68E512-4B55-44f4-BA5A-174B630A03DD ChildElement2 - Id: 3 - ParentId: 2 - CorrelationId: 4D68E512-4B55-44f4-BA5A-174B630A03DD ChildElement1 - Id: 4 - ParentId: 2 - CorrelationId: 4D68E512-4B55-44f4-BA5A-174B630A03DD In my case, I do have access to the correlationId, so I can retrieve all of my records by performing the following query: from element in db.Elements where element.CorrelationId == '4D68E512-4B55-44f4-BA5A-174B630A03DD' select element; But, of course, I want these elements associated with each other by executing this query: from element in db.Elements where element.CorrelationId == '4D68E512-4B55-44f4-BA5A-174B630A03DD' && element.ParentId == null select element; My question is: is it possible to combine the results the first query as some sort of 'caching mechanism' for the query where I get the root element? Thanks for the input. J.

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