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  • Laser range finder, what language to use? Beginner advice

    - by DrOnline
    I hope this is the right place. I am a programming beginner, and I want to make a laser range finder, and I need advice about how to proceed etc. In a few weeks I will get a lot of dirt cheap 3-5V lasers and some cheap usb webcams. I will point the laser and webcam in parallel, and somehow use trigonometry and programming to determined distance. I have seen online that others made done it this way, I have purposefully not looked at the details too much because I want to develop it on my own, and learn, but I know the general outline. I have a general idea of how to proceed. The program loads in a picture from the webcam, and I dunno how images work really, but I imagine there is a format that is basically an array of RGB values.. is this right? I will load in the red values, and find the most red one. I know the height difference between the laser and the cam. I know the center dot in the image, I know the redmost dot. I'm sure there's some way to figure out some range there. TO THE POINT: 1) Is my reasoning sound thus far, especially in terms of image analysis? I don't need complete solutions, just general points 2) What I need to figure out, is what platform to use. I have an arduino... apparently, I've read it's too weak to process images. Read that online. I know some C I know some Python I have Matlab. Which is the best option? I do not need high sampling rates, I have not decided on whether it should be automated or whether I should make a GUI with a button to press for samples. I will keep it simple and expand I think. I also do not need it to be super accurate, I'm just having fun here. Advice!

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  • Windows W8, L8 and now H8

    - by raccoon_tim
    Windows 8 is having to endure with a lot of headwind at the moment. The weather forecast doesn’t appear to improve in the near future either with prominent game developers and publishers taking to the barricades accusing Microsoft of building a closed ecosystem. I am forced to side with this opinion as I too see services the likes of Steam as playing an important role in the gaming world, which just happens to be an industry that cannot be sidelined. What Microsoft is attempting to do is merge the PC and mobile markets. The Windows Marketplace is to be the only place where you can purchase Windows applications in the future starting now with Metro apps. This is what Apple, Google and Microsoft have been doing with mobile devices for some time now and it’s what we have all come to expect. The PC market is different, however. It has always been open, which has resulted in a diverse market allowing for third parties to build successful distribution and marketing networks. You could argue that Microsoft is just doing something that Steam has been doing for a long time now but the difference is that Microsoft would own both the marketplace AND that operating system, which would eventually give it dominance over the whole Windows application distribution network. Currently there is no real alternative to Windows in the PC gaming world but I would expect to see Mac OS and Linux getting more popular if Microsoft does not notice the signals coming from the gaming industry and choose to once again open up the markets on the PC.

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  • How you choose your first job as a programmer? [on hold]

    - by sliter
    For Brief I am a recently graduated CS student. I am looking for a job these days, but I have no idea what kind of software development jobs I like(embedded system,web development or else...). And I am looking for your advice. Here is a little more While I was a student, I had an one year internship experience as a system engineer in a semi-conductor company where I wrote Linux driver, tuned system performance, etc.. I was happy about this experience as it allowed me to deepen my understanding of the operating system and different low level things. And I thought "Em, I will continue in the embedded area after I graduate". At the end of my study, I am doing an another internship in web development, both front-end and back-end. And I also enjoys a lot the process of learning new things and making it work (Backbone, Node, socketio, etc..). Now, when I am looking for a software development position, I do not know what to apply! All I know is that I want a job which allows me to keep up with the trends instead of repeating. But besides this, I've no idea what specific type of job I want to do. Turn back to embedded system? Continue with web development? Change to other promising areas(data mining)? All these development positions makes no big difference to me. But I think this is not good and I need some criteria at choosing. So I am looking for advice and I would really appreciate if you can share your experience.

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  • Significant amount of the time, I can't think of a reason to have an object instead of a static class. Do objects have more benefits than I think?

    - by Prog
    I understand the concept of an object, and as a Java programmer I feel the OO paradigm comes rather naturally to me in practice. However recently I found myself thinking: Wait a second, what are actually the practical benefits of using an object over using a static class (with proper encapsulation and OO practices)? I could think of two benefits of using an object (both significant and powerful): Polymorphism: allows you to swap functionality dynamically and flexibly during runtime. Also allows to add new functionality 'parts' and alternatives to the system easily. For example if there's a Car class designed to work with Engine objects, and you want to add a new Engine to the system that the Car can use, you can create a new Engine subclass and simply pass an object of this class into the Car object, without having to change anything about Car. And you can decide to do so during runtime. Being able to 'pass functionality around': you can pass an object around the system dynamically. But are there any more advantages to objects over static classes? Often when I add new 'parts' to a system, I do so by creating a new class and instantiating objects from it. But recently when I stopped and thought about it, I realized that a static class would do just the same as an object, in a lot of the places where I normally use an object. For example, I'm working on adding a save/load-file mechanism to my app. With an object, the calling line of code will look like this: Thing thing = fileLoader.load(file); With a static class, it would look like this: Thing thing = FileLoader.load(file); What's the difference? Fairly often I just can't think of a reason to instantiate an object when a plain-old static-class would act just the same. But in OO systems, static classes are fairly rare. So I must be missing something. Are there any more advantages to objects other from the two that I listed? Please explain.

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  • Which order to define getters and setters in? [closed]

    - by N.N.
    Is there a best practice for the order to define getters and setters in? There seems to be two practices: getter/setter pairs first getters, then setters (or the other way around) To illuminate the difference here is a Java example of getter/setter pairs: public class Foo { private int var1, var2, var3; public int getVar1() { return var1; } public void setVar1(int var1) { this.var1 = var1; } public int getVar2() { return var2; } public void setVar2(int var2) { this.var2 = var2; } public int getVar3() { return var3; } public void setVar3(int var3) { this.var3 = var3; } } And here is a Java example of first getters, then setters: public class Foo { private int var1, var2, var3; public int getVar1() { return var1; } public int getVar2() { return var2; } public int getVar3() { return var3; } public void setVar1(int var1) { this.var1 = var1; } public void setVar2(int var2) { this.var2 = var2; } public void setVar3(int var3) { this.var3 = var3; } } I think the latter type of ordering is clearer both in code and in class diagrams but I do not know if that is enough to rule out the other type of ordering.

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  • jquery small refactoring , json call

    - by Alexander Corotchi
    Hi everybody, I need you suggestion to make some refactoring in jquery code because now it looks terrible for me. I have 4 json calls but the difference it is just the URL call. EX: var userId = MyuserID; var perPage = '45'; var showOnPage = '45'; var tag = 'tag1'; var tag1 = 'tag2'; var tag2 = 'tagn'; $.getJSON('http://api.flickr.com/services/rest/?format=json&method='+ 'flickr.photos.search&api_key=' + apiKey + '&user_id=' + userId + '&tags=' + tag + '&per_page=' + perPage + '&jsoncallback=?', function(data){ var classShown = 'class="lightbox"'; var classHidden = 'class="lightbox hidden"'; $.each(data.photos.photo, function(i, rPhoto){ var basePhotoURL = 'http://farm' + rPhoto.farm + '.static.flickr.com/' + rPhoto.server + '/' + rPhoto.id + '_' + rPhoto.secret; var thumbPhotoURL = basePhotoURL + '_s.jpg'; var mediumPhotoURL = basePhotoURL + '.jpg'; var photoStringStart = '<li><a '; var photoStringEnd = 'title="' + rPhoto.title + '" href="'+ mediumPhotoURL +'"><img src="' + thumbPhotoURL + '" alt="' + rPhoto.title + '"/></a><span>'+rPhoto.title+'</span></li>;' var photoString = (i < showOnPage) ? photoStringStart + classShown + photoStringEnd : photoStringStart + classHidden + photoStringEnd; $(photoString).appendTo("#flickr ul"); }); $("#flickr a").fancybox(); }); $.getJSON('http://api.flickr.com/services/rest/?format=json&method='+ 'flickr.photos.search&api_key=' + apiKey + '&user_id=' + userId + '&tags=' + tag1 + '&per_page=' + perPage + '&jsoncallback=?', function(data){ var classShown = 'class="lightbox"'; var classHidden = 'class="lightbox hidden"'; $.each(data.photos.photo, function(i, rPhoto){ var basePhotoURL = 'http://farm' + rPhoto.farm + '.static.flickr.com/' + rPhoto.server + '/' + rPhoto.id + '_' + rPhoto.secret; var thumbPhotoURL = basePhotoURL + '_s.jpg'; var mediumPhotoURL = basePhotoURL + '.jpg'; var photoStringStart = '<li><a '; var photoStringEnd = 'title="' + rPhoto.title + '" href="'+ mediumPhotoURL +'"><img src="' + thumbPhotoURL + '" alt="' + rPhoto.title + '"/></a><span>'+rPhoto.title+'</span></li>;' var photoString = (i < showOnPage) ? photoStringStart + classShown + photoStringEnd : photoStringStart + classHidden + photoStringEnd; $(photoString).appendTo(".SetPinos1 ul"); }); $(".Sets a").fancybox(); }); $.getJSON('http://api.flickr.com/services/rest/?format=json&method='+ 'flickr.photos.search&api_key=' + apiKey + '&user_id=' + userId + '&tags=' + tagn + '&per_page=' + perPage + '&jsoncallback=?', function(data){ var classShown = 'class="lightbox"'; var classHidden = 'class="lightbox hidden"'; $.each(data.photos.photo, function(i, rPhoto){ var basePhotoURL = 'http://farm' + rPhoto.farm + '.static.flickr.com/' + rPhoto.server + '/' + rPhoto.id + '_' + rPhoto.secret; var thumbPhotoURL = basePhotoURL + '_s.jpg'; var mediumPhotoURL = basePhotoURL + '.jpg'; var photoStringStart = '<li><a '; var photoStringEnd = 'title="' + rPhoto.title + '" href="'+ mediumPhotoURL +'"><img src="' + thumbPhotoURL + '" alt="' + rPhoto.title + '"/></a><span>'+rPhoto.title+'</span></li>;' var photoString = (i < showOnPage) ? photoStringStart + classShown + photoStringEnd : photoStringStart + classHidden + photoStringEnd; $(photoString).appendTo(".SetPinos ul"); }); $(".Sets a").fancybox(); }); var tag is only one difference in this url : Can somebody help me not to repeat all this stuff ?? Sorry by so long garbage :(

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  • Padding error - when using AES Encryption in Java and Decryption in C

    - by user234445
    Hi All, I have a problem while decrypting the xl file in rijndael 'c' code (The file got encrypted in Java through JCE) and this problem is happening only for the excel files types which having formula's. Remaining all file type encryption/decryption is happening properly. (If i decrypt the same file in java the output is coming fine.) While i am dumped a file i can see the difference between java decryption and 'C' file decryption. od -c -b filename(file decrypted in C) 0034620 005 006 \0 \0 \0 \0 022 \0 022 \0 320 004 \0 \0 276 4 005 006 000 000 000 000 022 000 022 000 320 004 000 000 276 064 0034640 \0 \0 \0 \0 \f \f \f \f \f \f \f \f \f \f \f \f 000 000 000 000 014 014 014 014 014 014 014 014 014 014 014 014 0034660 od -c -b filename(file decrypted in Java) 0034620 005 006 \0 \0 \0 \0 022 \0 022 \0 320 004 \0 \0 276 4 005 006 000 000 000 000 022 000 022 000 320 004 000 000 276 064 0034640 \0 \0 \0 \0 000 000 000 000 0034644 (the above is the difference between the dumped files) The following java code i used to encrypt the file. public class AES { /** * Turns array of bytes into string * * @param buf Array of bytes to convert to hex string * @return Generated hex string */ public static void main(String[] args) throws Exception { File file = new File("testxls.xls"); byte[] lContents = new byte[(int) file.length()]; try { FileInputStream fileInputStream = new FileInputStream(file); fileInputStream.read(lContents); } catch (FileNotFoundException e) { e.printStackTrace(); } catch (IOException e1) { e1.printStackTrace(); } try { KeyGenerator kgen = KeyGenerator.getInstance("AES"); kgen.init(256); // 192 and 256 bits may not be available // Generate the secret key specs. SecretKey skey = kgen.generateKey(); //byte[] raw = skey.getEncoded(); byte[] raw = "aabbccddeeffgghhaabbccddeeffgghh".getBytes(); SecretKeySpec skeySpec = new SecretKeySpec(raw, "AES"); Cipher cipher = Cipher.getInstance("AES"); cipher.init(Cipher.ENCRYPT_MODE, skeySpec); byte[] encrypted = cipher.doFinal(lContents); cipher.init(Cipher.DECRYPT_MODE, skeySpec); byte[] original = cipher.doFinal(lContents); FileOutputStream f1 = new FileOutputStream("testxls_java.xls"); f1.write(original); } catch (Exception e) { // TODO Auto-generated catch block e.printStackTrace(); } } } I used the following file for decryption in 'C'. #include <stdio.h> #include "rijndael.h" #define KEYBITS 256 #include <stdio.h> #include "rijndael.h" #define KEYBITS 256 int main(int argc, char **argv) { unsigned long rk[RKLENGTH(KEYBITS)]; unsigned char key[KEYLENGTH(KEYBITS)]; int i; int nrounds; char dummy[100] = "aabbccddeeffgghhaabbccddeeffgghh"; char *password; FILE *input,*output; password = dummy; for (i = 0; i < sizeof(key); i++) key[i] = *password != 0 ? *password++ : 0; input = fopen("doc_for_logu.xlsb", "rb"); if (input == NULL) { fputs("File read error", stderr); return 1; } output = fopen("ori_c_res.xlsb","w"); nrounds = rijndaelSetupDecrypt(rk, key, 256); while (1) { unsigned char plaintext[16]; unsigned char ciphertext[16]; int j; if (fread(ciphertext, sizeof(ciphertext), 1, input) != 1) break; rijndaelDecrypt(rk, nrounds, ciphertext, plaintext); fwrite(plaintext, sizeof(plaintext), 1, output); } fclose(input); fclose(output); }

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  • "Local transaction already has 1 non-XA Resource: cannot add more resources" error

    - by jthg
    After reading previous questions about this error, it seems like all of them conclude that you need to enable XA on all of the data sources. But: What if I don't want a distributed transaction? What would I do if I want to start transactions on two different databases at the same time, but commit the transaction on one database and roll back the transaction on the other? I'm wondering how my code actually initiated a distributed transaction. It looks to me like I'm starting completely separate transactions on each of the databases. Info about the application: The application is an EJB running on a Sun Java Application Server 9.1 I use something like the following spring context to set up the hibernate session factories: <bean id="dbADatasource" class="org.springframework.jndi.JndiObjectFactoryBean"> <property name="jndiName" value="jdbc/dbA"/> </bean> <bean id="dbASessionFactory" class="org.springframework.orm.hibernate3.LocalSessionFactoryBean"> <property name="dataSource" ref="dbADatasource" /> <property name="hibernateProperties"> [hibernate properties...] </property> <property name="mappingResources"> [mapping resources...] </property> </bean> <bean id="dbBDatasource" class="org.springframework.jndi.JndiObjectFactoryBean"> <property name="jndiName" value="jdbc/dbB"/> </bean> <bean id="dbBSessionFactory" class="org.springframework.orm.hibernate3.LocalSessionFactoryBean"> <property name="dataSource" ref="dbBDatasource" /> <property name="hibernateProperties"> [hibernate properties...] </property> <property name="mappingResources"> [mapping resources...] </property> </bean> Both of the JNDI resources are javax.sql.ConnectionPoolDatasoure's. They actually both point to the same connection pool, but we have two different JNDI resources because there's the possibility that the two groups of tables will move to different databases in the future. Then in code, I do: sessionA = dbASessionFactory.openSession(); sessionB = dbBSessionFactory.openSession(); sessionA.beginTransaction(); sessionB.beginTransaction(); The sessionB.beginTransaction() line produces the error in the title of this post - sometimes. I ran the app on two different sun application servers. On one runs it fine, the other throws the error. I don't see any difference in how the two servers are configured although they do connect to different, but equivalent databases. So the question is Why doesn't the above code start completely independent transactions? How can I force it to start independent transactions rather than a distributed transaction? What configuration could cause the difference in behavior between the two application servers? Thanks.

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  • wpf exit thread automatically when application closes

    - by toni
    Hi, I have a main wpf window and one of its controls is a user control that I have created. this user control is an analog clock and contains a thread that update hour, minute and second hands. Initially it wasn't a thread, it was a timer event that updated the hour, minutes and seconds but I have changed it to a thread because the application do some hard work when the user press a start button and then the clock don't update so I changed it to a thread. COde snippet of wpf window: <Window xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:local="clr-namespace:GParts" xmlns:Microsoft_Windows_Themes="clr-namespace:Microsoft.Windows.Themes assembly=PresentationFramework.Aero" xmlns:UC="clr-namespace:GParts.UserControls" x:Class="GParts.WinMain" Title="GParts" WindowState="Maximized" Closing="Window_Closing" Icon="/Resources/Calendar-clock.png" x:Name="WMain" > <...> <!-- this is my user control --> <UC:AnalogClock Grid.Row="1" x:Name="AnalogClock" Background="Transparent" Margin="0" Height="Auto" Width="Auto"/> <...> </Window> My problem is when the user exits the application then the thread seems to continue executing. I would like the thread finishes automatically when main windows closes. code snippet of user control constructor: namespace GParts.UserControls { /// <summary> /// Lógica de interacción para AnalogClock.xaml /// </summary> public partial class AnalogClock : UserControl { System.Timers.Timer timer = new System.Timers.Timer(1000); public AnalogClock() { InitializeComponent(); MDCalendar mdCalendar = new MDCalendar(); DateTime date = DateTime.Now; TimeZone time = TimeZone.CurrentTimeZone; TimeSpan difference = time.GetUtcOffset(date); uint currentTime = mdCalendar.Time() + (uint)difference.TotalSeconds; christianityCalendar.Content = mdCalendar.Date("d/e/Z", currentTime, false); // this was before implementing thread //timer.Elapsed += new System.Timers.ElapsedEventHandler(timer_Elapsed); //timer.Enabled = true; // The Work to perform ThreadStart start = delegate() { // With this condition the thread exits when main window closes but // despite of this it seems like the thread continues executing after // exiting application because in task manager cpu is very busy // while ((this.IsInitialized) && (this.Dispatcher.HasShutdownFinished== false)) { this.Dispatcher.Invoke(DispatcherPriority.Normal, (Action)(() => { DateTime hora = DateTime.Now; secondHand.Angle = hora.Second * 6; minuteHand.Angle = hora.Minute * 6; hourHand.Angle = (hora.Hour * 30) + (hora.Minute * 0.5); DigitalClock.CurrentTime = hora; })); } Console.Write("Quit ok"); }; // Create the thread and kick it started! new Thread(start).Start(); } // this was before implementing thread void timer_Elapsed(object sender, System.Timers.ElapsedEventArgs e) { this.Dispatcher.Invoke(DispatcherPriority.Normal, (Action)(() => { DateTime hora = DateTime.Now; secondHand.Angle = hora.Second * 6; minuteHand.Angle = hora.Minute * 6; hourHand.Angle = (hora.Hour * 30) + (hora.Minute * 0.5); DigitalClock.CurrentTime = hora; })); } } // end class } // end namespace How can I exit correctly from thread automatically when main window closes and then application exits? Thanks very much!

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  • A rocket following the tracks height. Not Homing Missile.

    - by confusedEj
    What I am trying to create is a rocket that will hug the track in a straight direction. ie) The rocket travels in a straight direction and can orientate based on its local x axis. This is so it can go up/down ramps and never hit the ground. Currently I am using PhysX opengl and C++. This is the method I'm trying right now: 1. Ray cast from ahead of the missile (ray casting downwards) 2. If the ray cast is less then the expected ray cast length, then I have to orientate up. 3. If the ray cast is more then the expected ray cast length, then I have to orientate down. Now the problem, I am having is that my missile is orientating at an arbitary angle (I'm giving it 1 degrees.) Though I think this is a bad approach because the amount of frames in the game is not as much as I would think there would be. So the rocket would run into a ramp. My main question is: is there a better way of approaching this and how? NxVec3 frontRayLoc = m_rocketConfig->getValueForKey<NxVec3>("r_frontRayCastLocation"); float threshhold = m_rocketConfig->getValueForKey<float>("r_angleThreshhold"); float predRayCastHeight = m_rocketConfig->getValueForKey<float>("r_predRayCastHeight"); NxVec3 rayGlobalPos_1 = m_actor->getGlobalPosition() + m_actor->getGlobalOrientation() * frontRayLoc; NxVec3 dir = m_actor->getGlobalOrientation() * NxVec3(0,-1.0,0); NxReal dist1 = castRay(rayGlobalPos_1, dir); // Get the percentage difference float actualFrontHeight = abs(1 - (dist1/predRayCastHeight)); // See if the percentage difference is greater then threshold // Also check if we are being shot off track if ((actualFrontHeight > threshhold) && (dist1 != m_rayMaxDist)){ // Dip Down if (dist1 > predRayCastHeight){ printf("DOWN - Distance 1: %f\n", dist1); // Get axis of rotation NxVec3 newAxis = m_actor->getGlobalOrientation() * NxVec3(1.0,0,0.0); // Rotate based on that axis m_orientateAngle = -1.0 * m_orientateAngle; // For rotating clockwise NxQuat newOrientation(m_orientateAngle, newAxis); NxMat33 orientation(newOrientation); m_orientation = m_orientation * orientation; // Orientate the linear velocity to keep speed of rocket and direct away from road NxVec3 linVel = m_actor->getLinearVelocity(); m_actor->setLinearVelocity(m_orientation * linVel); } // Go Up else if (dist1 < predRayCastHeight){ printf("UP - Distance 1: %f\n", dist1); // Get axis of rotation NxVec3 newAxis = m_actor->getGlobalOrientation() * NxVec3(1.0,0,0.0); // Rotate around axis NxQuat newOrientation(m_orientateAngle, newAxis); m_actor->setGlobalOrientationQuat(newOrientation); NxMat33 orientation(newOrientation); m_orientation = m_orientation * orientation; // Orientate the linear velocity to keep speed of rocket and direct away from road NxVec3 linVel = m_actor->getLinearVelocity(); m_actor->setLinearVelocity(m_orientation*linVel); } m_actor->setGlobalOrientation(m_orientation); } Thanks for the support :)

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  • Building an external list while filtering in LINQ

    - by Khnle
    I have an array of input strings that contains either email addresses or account names in the form of domain\account. I would like to build a List of string that contains only email addresses. If an element in the input array is of the form domain\account, I will perform a lookup in the dictionary. If the key is found in the dictionary, that value is the email address. If not found, that won't get added to the result list. The code below will makes the above description clear: private bool where(string input, Dictionary<string, string> dict) { if (input.Contains("@")) { return true; } else { try { string value = dict[input]; return true; } catch (KeyNotFoundException) { return false; } } } private string select(string input, Dictionary<string, string> dict) { if (input.Contains("@")) { return input; } else { try { string value = dict[input]; return value; } catch (KeyNotFoundException) { return null; } } } public void run() { Dictionary<string, string> dict = new Dictionary<string, string>() { { "gmail\\nameless", "[email protected]"} }; string[] s = { "[email protected]", "gmail\\nameless", "gmail\\unknown" }; var q = s.Where(p => where(p, dict)).Select(p => select(p, dict)); List<string> resultList = q.ToList<string>(); } While the above code works (hope I don't have any typo here), there are 2 problems that I do not like with the above: The code in where() and select() seems to be redundant/repeating. It takes 2 passes. The second pass converts from the query expression to List. So I would like to add to the List resultList directly in the where() method. It seems like I should be able to do so. Here's the code: private bool where(string input, Dictionary<string, string> dict, List<string> resultList) { if (input.Contains("@")) { resultList.Add(input); //note the difference from above return true; } else { try { string value = dict[input]; resultList.Add(value); //note the difference from above return true; } catch (KeyNotFoundException) { return false; } } } The my LINQ expression can be nicely in 1 single statement: List<string> resultList = new List<string>(); s.Where(p => where(p, dict, resultList)); Or var q = s.Where(p => where(p, dict, resultList)); //do nothing with q afterward Which seems like perfect and legal C# LINQ. The result: sometime it works and sometime it doesn't. So why doesn't my code work reliably and how can I make it do so?

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  • Generated LinqtoSql Sql 5x slower than SAME EXACT hand-written sql

    - by JasonM
    I have a sql statement which is hardcoded in an existing VB6 app. I'm upgrading a new version in C# and using Linq To Sql. I was able to get LinqToSql to generate the same sql (before I start refactoring), but for some reason the Sql generated by LinqToSql is 5x slower than the original sql. This is running the generated Sql Directly in LinqPad. The only real difference my meager sql eyes can spot is the WITH (NOLOCK), which if I add into the LinqToSql generated sql, makes no difference. Can someone point out what I'm doing wrong here? Thanks! Existing Hard Coded Sql (5.0 Seconds) SELECT DISTINCT CH.ClaimNum, CH.AcnProvID, CH.AcnPatID, CH.TinNum, CH.Diag1, CH.GroupNum, CH.AllowedTotal FROM Claims.dbo.T_ClaimsHeader AS CH WITH (NOLOCK) WHERE CH.ContractID IN ('123A','123B','123C','123D','123E','123F','123G','123H') AND ( ( (CH.Transmited Is Null or CH.Transmited = '') AND CH.DateTransmit Is Null AND CH.EobDate Is Null AND CH.ProcessFlag IN ('Y','E') AND CH.DataSource NOT IN ('A','EC','EU') AND CH.AllowedTotal > 0 ) ) ORDER BY CH.AcnPatID, CH.ClaimNum Generated Sql from LinqToSql (27.6 Seconds) -- Region Parameters DECLARE @p0 NVarChar(4) SET @p0 = '123A' DECLARE @p1 NVarChar(4) SET @p1 = '123B' DECLARE @p2 NVarChar(4) SET @p2 = '123C' DECLARE @p3 NVarChar(4) SET @p3 = '123D' DECLARE @p4 NVarChar(4) SET @p4 = '123E' DECLARE @p5 NVarChar(4) SET @p5 = '123F' DECLARE @p6 NVarChar(4) SET @p6 = '123G' DECLARE @p7 NVarChar(4) SET @p7 = '123H' DECLARE @p8 VarChar(1) SET @p8 = '' DECLARE @p9 NVarChar(1) SET @p9 = 'Y' DECLARE @p10 NVarChar(1) SET @p10 = 'E' DECLARE @p11 NVarChar(1) SET @p11 = 'A' DECLARE @p12 NVarChar(2) SET @p12 = 'EC' DECLARE @p13 NVarChar(2) SET @p13 = 'EU' DECLARE @p14 Decimal(5,4) SET @p14 = 0 -- EndRegion SELECT DISTINCT [t0].[ClaimNum], [t0].[acnprovid] AS [AcnProvID], [t0].[acnpatid] AS [AcnPatID], [t0].[tinnum] AS [TinNum], [t0].[diag1] AS [Diag1], [t0].[GroupNum], [t0].[allowedtotal] AS [AllowedTotal] FROM [Claims].[dbo].[T_ClaimsHeader] AS [t0] WHERE ([t0].[contractid] IN (@p0, @p1, @p2, @p3, @p4, @p5, @p6, @p7)) AND (([t0].[Transmited] IS NULL) OR ([t0].[Transmited] = @p8)) AND ([t0].[DATETRANSMIT] IS NULL) AND ([t0].[EOBDATE] IS NULL) AND ([t0].[PROCESSFLAG] IN (@p9, @p10)) AND (NOT ([t0].[DataSource] IN (@p11, @p12, @p13))) AND ([t0].[allowedtotal] > @p14) ORDER BY [t0].[acnpatid], [t0].[ClaimNum] New LinqToSql Code (30+ seconds... Times out ) var contractIds = T_ContractDatas.Where(x => x.EdiSubmissionGroupID == "123-01").Select(x => x.CONTRACTID).ToList(); var processFlags = new List<string> {"Y","E"}; var dataSource = new List<string> {"A","EC","EU"}; var results = (from claims in T_ClaimsHeaders where contractIds.Contains(claims.contractid) && (claims.Transmited == null || claims.Transmited == string.Empty ) && claims.DATETRANSMIT == null && claims.EOBDATE == null && processFlags.Contains(claims.PROCESSFLAG) && !dataSource.Contains(claims.DataSource) && claims.allowedtotal > 0 select new { ClaimNum = claims.ClaimNum, AcnProvID = claims.acnprovid, AcnPatID = claims.acnpatid, TinNum = claims.tinnum, Diag1 = claims.diag1, GroupNum = claims.GroupNum, AllowedTotal = claims.allowedtotal }).OrderBy(x => x.ClaimNum).OrderBy(x => x.AcnPatID).Distinct(); I'm using the list of constants above to make LinqToSql Generate IN ('xxx','xxx',etc) Otherwise it uses subqueries which are just as slow...

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  • Using VLOOKUP in Excel

    - by Mark Virtue
    VLOOKUP is one of Excel’s most useful functions, and it’s also one of the least understood.  In this article, we demystify VLOOKUP by way of a real-life example.  We’ll create a usable Invoice Template for a fictitious company. So what is VLOOKUP?  Well, of course it’s an Excel function.  This article will assume that the reader already has a passing understanding of Excel functions, and can use basic functions such as SUM, AVERAGE, and TODAY.  In its most common usage, VLOOKUP is a database function, meaning that it works with database tables – or more simply, lists of things in an Excel worksheet.  What sort of things?   Well, any sort of thing.  You may have a worksheet that contains a list of employees, or products, or customers, or CDs in your CD collection, or stars in the night sky.  It doesn’t really matter. Here’s an example of a list, or database.  In this case it’s a list of products that our fictitious company sells: Usually lists like this have some sort of unique identifier for each item in the list.  In this case, the unique identifier is in the “Item Code” column.  Note:  For the VLOOKUP function to work with a database/list, that list must have a column containing the unique identifier (or “key”, or “ID”), and that column must be the first column in the table.  Our sample database above satisfies this criterion. The hardest part of using VLOOKUP is understanding exactly what it’s for.  So let’s see if we can get that clear first: VLOOKUP retrieves information from a database/list based on a supplied instance of the unique identifier. Put another way, if you put the VLOOKUP function into a cell and pass it one of the unique identifiers from your database, it will return you one of the pieces of information associated with that unique identifier.  In the example above, you would pass VLOOKUP an item code, and it would return to you either the corresponding item’s description, its price, or its availability (its “In stock” quantity).  Which of these pieces of information will it pass you back?  Well, you get to decide this when you’re creating the formula. If all you need is one piece of information from the database, it would be a lot of trouble to go to to construct a formula with a VLOOKUP function in it.  Typically you would use this sort of functionality in a reusable spreadsheet, such as a template.  Each time someone enters a valid item code, the system would retrieve all the necessary information about the corresponding item. Let’s create an example of this:  An Invoice Template that we can reuse over and over in our fictitious company. First we start Excel… …and we create ourselves a blank invoice: This is how it’s going to work:  The person using the invoice template will fill in a series of item codes in column “A”, and the system will retrieve each item’s description and price, which will be used to calculate the line total for each item (assuming we enter a valid quantity). For the purposes of keeping this example simple, we will locate the product database on a separate sheet in the same workbook: In reality, it’s more likely that the product database would be located in a separate workbook.  It makes little difference to the VLOOKUP function, which doesn’t really care if the database is located on the same sheet, a different sheet, or a completely different workbook. In order to test the VLOOKUP formula we’re about to write, we first enter a valid item code into cell A11: Next, we move the active cell to the cell in which we want information retrieved from the database by VLOOKUP to be stored.  Interestingly, this is the step that most people get wrong.  To explain further:  We are about to create a VLOOKUP formula that will retrieve the description that corresponds to the item code in cell A11.  Where do we want this description put when we get it?  In cell B11, of course.  So that’s where we write the VLOOKUP formula – in cell B11. Select cell B11: We need to locate the list of all available functions that Excel has to offer, so that we can choose VLOOKUP and get some assistance in completing the formula.  This is found by first clicking the Formulas tab, and then clicking Insert Function:   A box appears that allows us to select any of the functions available in Excel.  To find the one we’re looking for, we could type a search term like “lookup” (because the function we’re interested in is a lookup function).  The system would return us a list of all lookup-related functions in Excel.  VLOOKUP is the second one in the list.  Select it an click OK… The Function Arguments box appears, prompting us for all the arguments (or parameters) needed in order to complete the VLOOKUP function.  You can think of this box as the function is asking us the following questions: What unique identifier are you looking up in the database? Where is the database? Which piece of information from the database, associated with the unique identifier, do you wish to have retrieved for you? The first three arguments are shown in bold, indicating that they are mandatory arguments (the VLOOKUP function is incomplete without them and will not return a valid value).  The fourth argument is not bold, meaning that it’s optional:   We will complete the arguments in order, top to bottom. The first argument we need to complete is the Lookup_value argument.  The function needs us to tell it where to find the unique identifier (the item code in this case) that it should be retuning the description of.  We must select the item code we entered earlier (in A11). Click on the selector icon to the right of the first argument: Then click once on the cell containing the item code (A11), and press Enter: The value of “A11” is inserted into the first argument. Now we need to enter a value for the Table_array argument.  In other words, we need to tell VLOOKUP where to find the database/list.  Click on the selector icon next to the second argument: Now locate the database/list and select the entire list – not including the header line.  The database is located on a separate worksheet, so we first click on that worksheet tab: Next we select the entire database, not including the header line: …and press Enter.  The range of cells that represents the database (in this case “’Product Database’!A2:D7”) is entered automatically for us into the second argument. Now we need to enter the third argument, Col_index_num.  We use this argument to specify to VLOOKUP which piece of information from the database, associate with our item code in A11, we wish to have returned to us.  In this particular example, we wish to have the item’s description returned to us.  If you look on the database worksheet, you’ll notice that the “Description” column is the second column in the database.  This means that we must enter a value of “2” into the Col_index_num box: It is important to note that that we are not entering a “2” here because the “Description” column is in the B column on that worksheet.  If the database happened to start in column K of the worksheet, we would still enter a “2” in this field. Finally, we need to decide whether to enter a value into the final VLOOKUP argument, Range_lookup.  This argument requires either a true or false value, or it should be left blank.  When using VLOOKUP with databases (as is true 90% of the time), then the way to decide what to put in this argument can be thought of as follows: If the first column of the database (the column that contains the unique identifiers) is sorted alphabetically/numerically in ascending order, then it’s possible to enter a value of true into this argument, or leave it blank. If the first column of the database is not sorted, or it’s sorted in descending order, then you must enter a value of false into this argument As the first column of our database is not sorted, we enter false into this argument: That’s it!  We’ve entered all the information required for VLOOKUP to return the value we need.  Click the OK button and notice that the description corresponding to item code “R99245” has been correctly entered into cell B11: The formula that was created for us looks like this: If we enter a different item code into cell A11, we will begin to see the power of the VLOOKUP function:  The description cell changes to match the new item code: We can perform a similar set of steps to get the item’s price returned into cell E11.  Note that the new formula must be created in cell E11.  The result will look like this: …and the formula will look like this: Note that the only difference between the two formulae is the third argument (Col_index_num) has changed from a “2” to a “3” (because we want data retrieved from the 3rd column in the database). If we decided to buy 2 of these items, we would enter a “2” into cell D11.  We would then enter a simple formula into cell F11 to get the line total: =D11*E11 …which looks like this… Completing the Invoice Template We’ve learned a lot about VLOOKUP so far.  In fact, we’ve learned all we’re going to learn in this article.  It’s important to note that VLOOKUP can be used in other circumstances besides databases.  This is less common, and may be covered in future How-To Geek articles. Our invoice template is not yet complete.  In order to complete it, we would do the following: We would remove the sample item code from cell A11 and the “2” from cell D11.  This will cause our newly created VLOOKUP formulae to display error messages: We can remedy this by judicious use of Excel’s IF() and ISBLANK() functions.  We change our formula from this…       =VLOOKUP(A11,’Product Database’!A2:D7,2,FALSE) …to this…       =IF(ISBLANK(A11),”",VLOOKUP(A11,’Product Database’!A2:D7,2,FALSE)) We would copy the formulas in cells B11, E11 and F11 down to the remainder of the item rows of the invoice.  Note that if we do this, the resulting formulas will no longer correctly refer to the database table.  We could fix this by changing the cell references for the database to absolute cell references.  Alternatively – and even better – we could create a range name for the entire product database (such as “Products”), and use this range name instead of the cell references.  The formula would change from this…       =IF(ISBLANK(A11),”",VLOOKUP(A11,’Product Database’!A2:D7,2,FALSE)) …to this…       =IF(ISBLANK(A11),”",VLOOKUP(A11,Products,2,FALSE)) …and then copy the formulas down to the rest of the invoice item rows. We would probably “lock” the cells that contain our formulae (or rather unlock the other cells), and then protect the worksheet, in order to ensure that our carefully constructed formulae are not accidentally overwritten when someone comes to fill in the invoice. We would save the file as a template, so that it could be reused by everyone in our company If we were feeling really clever, we would create a database of all our customers in another worksheet, and then use the customer ID entered in cell F5 to automatically fill in the customer’s name and address in cells B6, B7 and B8. If you would like to practice with VLOOKUP, or simply see our resulting Invoice Template, it can be downloaded from here. Similar Articles Productive Geek Tips Make Excel 2007 Print Gridlines In Workbook FileMake Excel 2007 Always Save in Excel 2003 FormatConvert Older Excel Documents to Excel 2007 FormatImport Microsoft Access Data Into ExcelChange the Default Font in Excel 2007 TouchFreeze Alternative in AutoHotkey The Icy Undertow Desktop Windows Home Server – Backup to LAN The Clear & Clean Desktop Use This Bookmarklet to Easily Get Albums Use AutoHotkey to Assign a Hotkey to a Specific Window Latest Software Reviews Tinyhacker Random Tips DVDFab 6 Revo Uninstaller Pro Registry Mechanic 9 for Windows PC Tools Internet Security Suite 2010 Classic Cinema Online offers 100’s of OnDemand Movies OutSync will Sync Photos of your Friends on Facebook and Outlook Windows 7 Easter Theme YoWindoW, a real time weather screensaver Optimize your computer the Microsoft way Stormpulse provides slick, real time weather data

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  • Beware Sneaky Reads with Unique Indexes

    - by Paul White NZ
    A few days ago, Sandra Mueller (twitter | blog) asked a question using twitter’s #sqlhelp hash tag: “Might SQL Server retrieve (out-of-row) LOB data from a table, even if the column isn’t referenced in the query?” Leaving aside trivial cases (like selecting a computed column that does reference the LOB data), one might be tempted to say that no, SQL Server does not read data you haven’t asked for.  In general, that’s quite correct; however there are cases where SQL Server might sneakily retrieve a LOB column… Example Table Here’s a T-SQL script to create that table and populate it with 1,000 rows: CREATE TABLE dbo.LOBtest ( pk INTEGER IDENTITY NOT NULL, some_value INTEGER NULL, lob_data VARCHAR(MAX) NULL, another_column CHAR(5) NULL, CONSTRAINT [PK dbo.LOBtest pk] PRIMARY KEY CLUSTERED (pk ASC) ); GO DECLARE @Data VARCHAR(MAX); SET @Data = REPLICATE(CONVERT(VARCHAR(MAX), 'x'), 65540);   WITH Numbers (n) AS ( SELECT ROW_NUMBER() OVER (ORDER BY (SELECT 0)) FROM master.sys.columns C1, master.sys.columns C2 ) INSERT LOBtest WITH (TABLOCKX) ( some_value, lob_data ) SELECT TOP (1000) N.n, @Data FROM Numbers N WHERE N.n <= 1000; Test 1: A Simple Update Let’s run a query to subtract one from every value in the some_value column: UPDATE dbo.LOBtest WITH (TABLOCKX) SET some_value = some_value - 1; As you might expect, modifying this integer column in 1,000 rows doesn’t take very long, or use many resources.  The STATITICS IO and TIME output shows a total of 9 logical reads, and 25ms elapsed time.  The query plan is also very simple: Looking at the Clustered Index Scan, we can see that SQL Server only retrieves the pk and some_value columns during the scan: The pk column is needed by the Clustered Index Update operator to uniquely identify the row that is being changed.  The some_value column is used by the Compute Scalar to calculate the new value.  (In case you are wondering what the Top operator is for, it is used to enforce SET ROWCOUNT). Test 2: Simple Update with an Index Now let’s create a nonclustered index keyed on the some_value column, with lob_data as an included column: CREATE NONCLUSTERED INDEX [IX dbo.LOBtest some_value (lob_data)] ON dbo.LOBtest (some_value) INCLUDE ( lob_data ) WITH ( FILLFACTOR = 100, MAXDOP = 1, SORT_IN_TEMPDB = ON ); This is not a useful index for our simple update query; imagine that someone else created it for a different purpose.  Let’s run our update query again: UPDATE dbo.LOBtest WITH (TABLOCKX) SET some_value = some_value - 1; We find that it now requires 4,014 logical reads and the elapsed query time has increased to around 100ms.  The extra logical reads (4 per row) are an expected consequence of maintaining the nonclustered index. The query plan is very similar to before (click to enlarge): The Clustered Index Update operator picks up the extra work of maintaining the nonclustered index. The new Compute Scalar operators detect whether the value in the some_value column has actually been changed by the update.  SQL Server may be able to skip maintaining the nonclustered index if the value hasn’t changed (see my previous post on non-updating updates for details).  Our simple query does change the value of some_data in every row, so this optimization doesn’t add any value in this specific case. The output list of columns from the Clustered Index Scan hasn’t changed from the one shown previously: SQL Server still just reads the pk and some_data columns.  Cool. Overall then, adding the nonclustered index hasn’t had any startling effects, and the LOB column data still isn’t being read from the table.  Let’s see what happens if we make the nonclustered index unique. Test 3: Simple Update with a Unique Index Here’s the script to create a new unique index, and drop the old one: CREATE UNIQUE NONCLUSTERED INDEX [UQ dbo.LOBtest some_value (lob_data)] ON dbo.LOBtest (some_value) INCLUDE ( lob_data ) WITH ( FILLFACTOR = 100, MAXDOP = 1, SORT_IN_TEMPDB = ON ); GO DROP INDEX [IX dbo.LOBtest some_value (lob_data)] ON dbo.LOBtest; Remember that SQL Server only enforces uniqueness on index keys (the some_data column).  The lob_data column is simply stored at the leaf-level of the non-clustered index.  With that in mind, we might expect this change to make very little difference.  Let’s see: UPDATE dbo.LOBtest WITH (TABLOCKX) SET some_value = some_value - 1; Whoa!  Now look at the elapsed time and logical reads: Scan count 1, logical reads 2016, physical reads 0, read-ahead reads 0, lob logical reads 36015, lob physical reads 0, lob read-ahead reads 15992.   CPU time = 172 ms, elapsed time = 16172 ms. Even with all the data and index pages in memory, the query took over 16 seconds to update just 1,000 rows, performing over 52,000 LOB logical reads (nearly 16,000 of those using read-ahead). Why on earth is SQL Server reading LOB data in a query that only updates a single integer column? The Query Plan The query plan for test 3 looks a bit more complex than before: In fact, the bottom level is exactly the same as we saw with the non-unique index.  The top level has heaps of new stuff though, which I’ll come to in a moment. You might be expecting to find that the Clustered Index Scan is now reading the lob_data column (for some reason).  After all, we need to explain where all the LOB logical reads are coming from.  Sadly, when we look at the properties of the Clustered Index Scan, we see exactly the same as before: SQL Server is still only reading the pk and some_value columns – so what’s doing the LOB reads? Updates that Sneakily Read Data We have to go as far as the Clustered Index Update operator before we see LOB data in the output list: [Expr1020] is a bit flag added by an earlier Compute Scalar.  It is set true if the some_value column has not been changed (part of the non-updating updates optimization I mentioned earlier). The Clustered Index Update operator adds two new columns: the lob_data column, and some_value_OLD.  The some_value_OLD column, as the name suggests, is the pre-update value of the some_value column.  At this point, the clustered index has already been updated with the new value, but we haven’t touched the nonclustered index yet. An interesting observation here is that the Clustered Index Update operator can read a column into the data flow as part of its update operation.  SQL Server could have read the LOB data as part of the initial Clustered Index Scan, but that would mean carrying the data through all the operations that occur prior to the Clustered Index Update.  The server knows it will have to go back to the clustered index row to update it, so it delays reading the LOB data until then.  Sneaky! Why the LOB Data Is Needed This is all very interesting (I hope), but why is SQL Server reading the LOB data?  For that matter, why does it need to pass the pre-update value of the some_value column out of the Clustered Index Update? The answer relates to the top row of the query plan for test 3.  I’ll reproduce it here for convenience: Notice that this is a wide (per-index) update plan.  SQL Server used a narrow (per-row) update plan in test 2, where the Clustered Index Update took care of maintaining the nonclustered index too.  I’ll talk more about this difference shortly. The Split/Sort/Collapse combination is an optimization, which aims to make per-index update plans more efficient.  It does this by breaking each update into a delete/insert pair, reordering the operations, removing any redundant operations, and finally applying the net effect of all the changes to the nonclustered index. Imagine we had a unique index which currently holds three rows with the values 1, 2, and 3.  If we run a query that adds 1 to each row value, we would end up with values 2, 3, and 4.  The net effect of all the changes is the same as if we simply deleted the value 1, and added a new value 4. By applying net changes, SQL Server can also avoid false unique-key violations.  If we tried to immediately update the value 1 to a 2, it would conflict with the existing value 2 (which would soon be updated to 3 of course) and the query would fail.  You might argue that SQL Server could avoid the uniqueness violation by starting with the highest value (3) and working down.  That’s fine, but it’s not possible to generalize this logic to work with every possible update query. SQL Server has to use a wide update plan if it sees any risk of false uniqueness violations.  It’s worth noting that the logic SQL Server uses to detect whether these violations are possible has definite limits.  As a result, you will often receive a wide update plan, even when you can see that no violations are possible. Another benefit of this optimization is that it includes a sort on the index key as part of its work.  Processing the index changes in index key order promotes sequential I/O against the nonclustered index. A side-effect of all this is that the net changes might include one or more inserts.  In order to insert a new row in the index, SQL Server obviously needs all the columns – the key column and the included LOB column.  This is the reason SQL Server reads the LOB data as part of the Clustered Index Update. In addition, the some_value_OLD column is required by the Split operator (it turns updates into delete/insert pairs).  In order to generate the correct index key delete operation, it needs the old key value. The irony is that in this case the Split/Sort/Collapse optimization is anything but.  Reading all that LOB data is extremely expensive, so it is sad that the current version of SQL Server has no way to avoid it. Finally, for completeness, I should mention that the Filter operator is there to filter out the non-updating updates. Beating the Set-Based Update with a Cursor One situation where SQL Server can see that false unique-key violations aren’t possible is where it can guarantee that only one row is being updated.  Armed with this knowledge, we can write a cursor (or the WHILE-loop equivalent) that updates one row at a time, and so avoids reading the LOB data: SET NOCOUNT ON; SET STATISTICS XML, IO, TIME OFF;   DECLARE @PK INTEGER, @StartTime DATETIME; SET @StartTime = GETUTCDATE();   DECLARE curUpdate CURSOR LOCAL FORWARD_ONLY KEYSET SCROLL_LOCKS FOR SELECT L.pk FROM LOBtest L ORDER BY L.pk ASC;   OPEN curUpdate;   WHILE (1 = 1) BEGIN FETCH NEXT FROM curUpdate INTO @PK;   IF @@FETCH_STATUS = -1 BREAK; IF @@FETCH_STATUS = -2 CONTINUE;   UPDATE dbo.LOBtest SET some_value = some_value - 1 WHERE CURRENT OF curUpdate; END;   CLOSE curUpdate; DEALLOCATE curUpdate;   SELECT DATEDIFF(MILLISECOND, @StartTime, GETUTCDATE()); That completes the update in 1280 milliseconds (remember test 3 took over 16 seconds!) I used the WHERE CURRENT OF syntax there and a KEYSET cursor, just for the fun of it.  One could just as well use a WHERE clause that specified the primary key value instead. Clustered Indexes A clustered index is the ultimate index with included columns: all non-key columns are included columns in a clustered index.  Let’s re-create the test table and data with an updatable primary key, and without any non-clustered indexes: IF OBJECT_ID(N'dbo.LOBtest', N'U') IS NOT NULL DROP TABLE dbo.LOBtest; GO CREATE TABLE dbo.LOBtest ( pk INTEGER NOT NULL, some_value INTEGER NULL, lob_data VARCHAR(MAX) NULL, another_column CHAR(5) NULL, CONSTRAINT [PK dbo.LOBtest pk] PRIMARY KEY CLUSTERED (pk ASC) ); GO DECLARE @Data VARCHAR(MAX); SET @Data = REPLICATE(CONVERT(VARCHAR(MAX), 'x'), 65540);   WITH Numbers (n) AS ( SELECT ROW_NUMBER() OVER (ORDER BY (SELECT 0)) FROM master.sys.columns C1, master.sys.columns C2 ) INSERT LOBtest WITH (TABLOCKX) ( pk, some_value, lob_data ) SELECT TOP (1000) N.n, N.n, @Data FROM Numbers N WHERE N.n <= 1000; Now here’s a query to modify the cluster keys: UPDATE dbo.LOBtest SET pk = pk + 1; The query plan is: As you can see, the Split/Sort/Collapse optimization is present, and we also gain an Eager Table Spool, for Halloween protection.  In addition, SQL Server now has no choice but to read the LOB data in the Clustered Index Scan: The performance is not great, as you might expect (even though there is no non-clustered index to maintain): Table 'LOBtest'. Scan count 1, logical reads 2011, physical reads 0, read-ahead reads 0, lob logical reads 36015, lob physical reads 0, lob read-ahead reads 15992.   Table 'Worktable'. Scan count 1, logical reads 2040, physical reads 0, read-ahead reads 0, lob logical reads 34000, lob physical reads 0, lob read-ahead reads 8000.   SQL Server Execution Times: CPU time = 483 ms, elapsed time = 17884 ms. Notice how the LOB data is read twice: once from the Clustered Index Scan, and again from the work table in tempdb used by the Eager Spool. If you try the same test with a non-unique clustered index (rather than a primary key), you’ll get a much more efficient plan that just passes the cluster key (including uniqueifier) around (no LOB data or other non-key columns): A unique non-clustered index (on a heap) works well too: Both those queries complete in a few tens of milliseconds, with no LOB reads, and just a few thousand logical reads.  (In fact the heap is rather more efficient). There are lots more fun combinations to try that I don’t have space for here. Final Thoughts The behaviour shown in this post is not limited to LOB data by any means.  If the conditions are met, any unique index that has included columns can produce similar behaviour – something to bear in mind when adding large INCLUDE columns to achieve covering queries, perhaps. Paul White Email: [email protected] Twitter: @PaulWhiteNZ

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  • Active and Passive Federation in WIF

    - by user102533
    I am trying to understand the difference between Active and Passive federation in WIF. It appears that one would use an Active Federation if the Relying Party (RP) is a WCF Service instead of an ASP.NET application and a Passive Federation if the RP is an ASP.NET application. Is this accurate? So, in a scenario in which an ASP.NET application uses a WCF in the backend, the MS articles suggest using a 'bootstrap' security token that is obtained by the ASP.NET app using an ActAs STS and this token is used to authenticate with the WCF. In this scenario, it appears that we are doing a combination of Active (user - STS - ASP.NET RP) and Passive (ASP.NET - ActAs STS - WCF) Federation?

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  • What is the differnce between DataTemplate and DataContext in WPF?

    - by Ashish Ashu
    I can set the relationship b/w View Model and view through following DataContext syntax: <UserControl.DataContext> <view_model:MainMenuModel /> </UserControl.DataContext> And I can also set the relationship b/w View Model and view through following DataTemplate syntax: <DataTemplate DataType="{x:Type viewModel:UserViewModel}"> <view:UserView /> </DataTemplate> Please let me know what is the difference between the two ? Is the second XAML does not set the data context of a view ?

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  • "There were build errors. Would you like to continue and run the last successful build?" not showing

    - by Kevin Wilson
    Hi, Not a massive problem but something that has been bugging the life out of me... One of my colleagues was trying out some code on my machine and got the "There were build errors. Would you like to continue and run the last successful build?" pop-up when the build failed on Visual Studio. He clicked on the "don't show this again" checkbox and closed the dialogue. My problem is that I can't get the dialogue to show up again. I found these instructions online: "Select Tools, Options, Projects and Solutions, Build and Run. Then set the option "On run, when build or deployment errors occur" to Prompt to Launch." but that doesn't work. Resetting the IDE settings to default don't make any difference either. Is there any way to get this dialogue back or has it gone forever? Thanks, K

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  • Why does calling setScaleX during pinch zoom gesture cause flicker?

    - by numan
    I am trying to create a zoomable container and I am targeting API 14+ In my onScale (i am using the ScaleGestureDetector to detect pinch-zoom) I am doing something like this: public boolean onScale (ScaleGestureDetector detector) { float scaleFactor = detector.getScaleFactor(); setScaleX(getScaleX() * scaleFactor); setScaleY(getScaleY() * scaleFactor); return true; }; It works but the zoom is not smooth. In fact it noticeably flickers. I also tried it with hardware layer thinking that the scaling would happen on the GPU once the texture was uploaded and thus would be super fast. But it made no difference - the zoom is not smooth and flickers weirdly sometimes. What am I doing wrong?

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  • Why won't OpenCV compile in NVCC?

    - by zenna
    Hi there I am trying to integrate CUDA and openCV in a project. Problem is openCV won't compile when NVCC is used, while a normal c++ project compiles just fine. This seems odd to me, as I thought NVCC passed all host code to the c/c++ compiler, in this case the visual studio compiler. The errors I get are? c:\opencv2.0\include\opencv\cxoperations.hpp(1137): error: no operator "=" matches these operands operand types are: const cv::Range = cv::Range c:\opencv2.0\include\opencv\cxoperations.hpp(2469): error: more than one instance of overloaded function "std::abs" matches the argument list: function "abs(long double)" function "abs(float)" function "abs(double)" function "abs(long)" function "abs(int)" argument types are: (ptrdiff_t) So my question is why the difference considering the same compiler (should be) is being used and secondly how I could remedy this.

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  • iTextSharp renders image with poor quality in PDF

    - by Sebastian
    Hello, I'm using iTextSharp to print a PDF document. Everything goes ok until I have to print the company logo in it. First I noticed that the logo had poor quality, but after testing with several images, I realize that was the iTextSharp rendering it poorly. The test I did to say this was to print the PDF using my code and then edit the document with Acrobat 8.0 and I drew an image. Then printed the two documents and saw the noticeable difference. My question is that if anyone know if this can be due to a scaling problem where I'm failing to tell iTextSharp how it must render the image or is an iTextSharp limitation. The code to render the image is the following: Dim para As Paragraph = New Paragraph para.Alignment = Image.RIGHT_ALIGN para.Add(text) Dim imageFile As String = String.Format("{0}{1}", GetAppSetting("UploadDirectory"), myCompany.LogoUrl) Dim thisImage As Image = Image.GetInstance(imageFile) thisImage.Alignment = Image.LEFT_ALIGN para.Add(thisImage) The printed images are the following: Image printed directly with iTextSharp Image edited and printed with Acrobat 8 Please let me know if I need to provide more info. Thanks

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  • netbeans 6.8 php, xdebug, mamp - cannot establish a connection

    - by Mike
    I'm having no luck whatsoever with debuggers either on Zend Studio or NetBeans. I cannot believe the difficulty I'm having with these IDE's. I've read all the prior questions on netbeans-xdebug problems. According to those answers, my configuration is correct. Nonetheless, when I try to run xdebug, NetBeans hangs. I cancel the connection and get the popup dialog: "There is no connection, blah blah blah..." Here's my php.ini [xdebug] ; Xdebug config for Mac OS X and NetBeans IDE zend_extension=/Applications/MAMP/bin/php5/lib/php/extensions/no-debug-non-zts-20060613/xdebug.so xdebug.remote_enable=on xdebug.remote_handler=dbgp xdebug.remote_mode=req xdebug.remote_host=127.0.0.1 xdebug.remote_port=9000 xdebug.idekey=netbeans-xdebug In NetBeans preferences, my session ID = netbeans-xdebug. I tried xdebug.idekey="netbeans-xdebug" That made no difference. I restarted the web server every time. Anyone have any other suggestions I might try? Thanks.

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  • Automation testing tool for Regression testing of desktop application

    - by user285037
    Hi I am working on a desktop application which uses Infragistic grids. We need to automate the regression tests for same. QTP alone does not support this, we need to buy new plug in for same which my company is not very much interested in. Do we have any open source tool for automating regression testing of desktop application? Application is in Dot net but i do not think it makes much of a difference. Please suggests, i have zeroed in for test complete but again it is licensed one. I need some open source.

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  • jQuery issue - #<an Object> has no method

    - by Shaun
    I've tried a veriety of jQuery plugins recently and I keep getting this error … … regardless of what plugin I try to use. I've checked the links to the JS files which are all there and working fine. I'm using Drupal if that makes any difference. I've run the plugins away from the main site to demonstrate that they are working and that I am doing things right with 100% success. Any ideas? Update: My jQuery file called in the footer: $(document).ready(function() { $('#footer_holder').hide(); // Fancy Box $("a.fancybox").fancybox({ 'hideOnContentClick': true, 'titlePosition' : 'over', 'transitionIn' : 'elastic', 'transitionOut' : 'elastic', 'speedIn' : 600, 'speedOut' : 200, 'overlayShow' : false, }); $("#homepage_slider").easySlider({ auto: true, continuous: true, }); }); *note - fancy box works fine. jQuery is sorted out by Drupal. I'm running version 1.4

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  • Creating .NET 3.0 sub-applications within .NET 1.1 applications in IIS/ASP.Net

    - by Karen
    I am basically trying to do the same thing as this question, create a new application within a folder so it could be accessed as follows. * http://www.domain.com/ < Main App * http://www.domain.com/newapp < New App The problem is that newapp is reading the web.config from the Main App, which is causing errors because it doesn't have all the same dlls etc. For New App, in IIS, the starting point is set at /newapp, so I am not sure why it is reading the web.config from / at all. It is set as it's own application. I am testing this in IIS6 on XP Pro, so not sure if that makes a difference. The Main App is dotnet 1.1, and New App is 3.0. Edit: Adding 'inheritInChildApplications to <location doesn't work in 1.1, you get an error: Parser Error Message: Unrecognized attribute 'inheritInChildApplications'

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  • Creating sub-applications within applications in IIS/ASP.Net

    - by Karen
    I am basically trying to do the same thing as this question, create a new application within a folder so it could be accessed as follows. * http://www.domain.com/ < Main App * http://www.domain.com/newapp < New App The problem is that newapp is reading the web.config from the Main App, which is causing errors because it doesn't have all the same dlls etc. For New App, in IIS, the starting point is set at /newapp, so I am not sure why it is reading the web.config from / at all. It is set as it's own application. I am testing this in IIS6 on XP Pro, so not sure if that makes a difference. The Main App is dotnet 1.1, and New App is 3.0.

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