Search Results

Search found 12988 results on 520 pages for 'performance'.

Page 490/520 | < Previous Page | 486 487 488 489 490 491 492 493 494 495 496 497  | Next Page >

• Java Nimbus LAF with transparent text fields

  - by Software Monkey

  I have an application that uses disabled JTextFields in several places which are intended to be transparent - allowing the background to show through instead of the text field's normal background. When running the new Nimbus LAF these fields are opaque (despite setting setOpaque(false)), and my UI is broken. It's as if the LAF is ignoring the opaque property. Setting a background color explicitly is both difficult in several places, and less than optimal due to background images actually doesn't work - it still paints it's LAF default background over the top, leaving a border-like appearance (the splash screen below has the background explicitly set to match the image). Any ideas on how I can get Nimbus to not paint the background for a JTextField? Note: I need a JTextField, rather than a JLabel, because I need the thread-safe setText(), and wrapping capability. Note: My fallback position is to continue using the system LAF, but Nimbus does look substantially better. See example images below. Conclusions The surprise at this behavior is due to a misinterpretation of what setOpaque() is meant to do - from the Nimbus bug report: This is a problem the the orginal design of Swing and how it has been confusing for years. The issue is setOpaque(false) has had a side effect in exiting LAFs which is that of hiding the background which is not really what it is ment for. It is ment to say that the component my have transparent parts and swing should paint the parent component behind it. It's unfortunate that the Nimbus components also appear not to honor setBackground(null) which would otherwise be the recommended way to stop the background painting. Setting a fully transparent background seems unintuitive to me. In my opinion, setOpaque()/isOpaque() is a faulty public API choice which should have been only: public boolean isFullyOpaque(); I say this, because isOpaque()==true is a contract with Swing that the component subclass will take responsibility for painting it's entire background - which means the parent can skip painting that region if it wants (which is an important performance enhancement). Something external cannot directly change this contract (legitimately), whose fulfillment may be coded into the component. So the opacity of the component should not have been settable using setOpaque(). Instead something like setBackground(null) should cause many components to "no long have a background" and therefore become not fully opaque. By way of example, in an ideal world most components should have an isOpaque() that looks like this: public boolean isOpaque() { return (background!=null); }

  Read the article

• How do I create a partial function with generics in scala?

  - by Matteo Caprari

  Hello. I'm trying to write a performance measurements library for Scala. My idea is to transparently 'mark' sections so that the execution time can be collected. Unfortunately I wasn't able to bend the compiler to my will. An admittedly contrived example of what I have in mind: // generate a timing function val myTimer = mkTimer('myTimer) // see how the timing function returns the right type depending on the // type of the function it is passed to it val act = actor { loop { receive { case 'Int => val calc = myTimer { (1 to 100000).sum } val result = calc + 10 // calc must be Int self reply (result) case 'String => val calc = myTimer { (1 to 100000).mkString } val result = calc + " String" // calc must be String self reply (result) } Now, this is the farthest I got: trait Timing { def time[T <: Any](name: Symbol)(op: => T) :T = { val start = System.nanoTime val result = op val elapsed = System.nanoTime - start println(name + ": " + elapsed) result } def mkTimer[T <: Any](name: Symbol) : (() => T) => () => T = { type c = () => T time(name)(_ : c) } } Using the time function directly works and the compiler correctly uses the return type of the anonymous function to type the 'time' function: val bigString = time('timerBigString) { (1 to 100000).mkString("-") } println (bigString) Great as it seems, this pattern has a number of shortcomings: forces the user to reuse the same symbol at each invocation makes it more difficult to do more advanced stuff like predefined project-level timers does not allow the library to initialize once a data structure for 'timerBigString So here it comes mkTimer, that would allow me to partially apply the time function and reuse it. I use mkTimer like this: val myTimer = mkTimer('aTimer) val myString= myTimer { (1 to 100000).mkString("-") } println (myString) But I get a compiler error: error: type mismatch; found : String required: () => Nothing (1 to 100000).mkString("-") I get the same error if I inline the currying: val timerBigString = time('timerBigString) _ val bigString = timerBigString { (1 to 100000).mkString("-") } println (bigString) This works if I do val timerBigString = time('timerBigString) (_: String), but this is not what I want. I'd like to defer typing of the partially applied function until application. I conclude that the compiler is deciding the return type of the partial function when I first create it, chosing "Nothing" because it can't make a better informed choice. So I guess what I'm looking for is a sort of late-binding of the partially applied function. Is there any way to do this? Or maybe is there a completely different path I could follow? Well, thanks for reading this far -teo

  Read the article

• NSStringWithFormat Swizzled to allow missing format numbered args

  - by coneybeare

  Based on this SO question asked a few hours ago, I have decided to implement a swizzled method that will allow me to take a formatted NSString as the format arg into stringWithFormat, and have it not break when omitting one of the numbered arg references (%1$@, %2$@) I have it working, but this is the first copy, and seeing as this method is going to be potentially called hundreds of thousands of times per app run, I need to bounce this off of some experts to see if this method has any red flags, major performance hits, or optimizations #define NUMARGS(...) (sizeof((int[]){__VA_ARGS__})/sizeof(int)) @implementation NSString (UAFormatOmissions) + (id)uaStringWithFormat:(NSString *)format, ... { if (format != nil) { va_list args; va_start(args, format); // $@ is an ordered variable (%1$@, %2$@...) if ([format rangeOfString:@"$@"].location == NSNotFound) { //call apples method NSString *s = [[[NSString alloc] initWithFormat:format arguments:args] autorelease]; va_end(args); return s; } NSMutableArray *newArgs = (NSMutableArray *)[NSMutableArray arrayWithCapacity:NUMARGS(args)]; id arg = nil; int i = 1; while (arg = va_arg(args, id)) { NSString *f = (NSString *)[NSString stringWithFormat:@"%%%d\$\@", i]; i++; if ([format rangeOfString:f].location == NSNotFound) continue; else [newArgs addObject:arg]; } va_end(args); char *newArgList = (char *)malloc(sizeof(id) * [newArgs count]); [newArgs getObjects:(id *)newArgList]; NSString* result = [[[NSString alloc] initWithFormat:format arguments:newArgList] autorelease]; free(newArgList); return result; } return nil; } The basic algorithm is: search the format string for the %1$@, %2$@ variables by searching for %@ if not found, call the normal stringWithFormat and return else, loop over the args if the format has a position variable (%i$@) for position i, add the arg to the new arg array else, don't add the arg take the new arg array, convert it back into a va_list, and call initWithFormat:arguments: to get the correct string. The idea is that I would run all [NSString stringWithFormat:] calls through this method instead. This might seem unnecessary to many, but click on to the referenced SO question (first line) to see examples of why I need to do this. Ideas? Thoughts? Better implementations? Better Solutions?

  Read the article

• SQL Server stored procedures - update column based on variable name..?

  - by ClarkeyBoy

  Hi, I have a data driven site with many stored procedures. What I want to eventually be able to do is to say something like: For Each @variable in sproc inputs UPDATE @TableName SET @variable.toString = @variable Next I would like it to be able to accept any number of arguments. It will basically loop through all of the inputs and update the column with the name of the variable with the value of the variable - for example column "Name" would be updated with the value of @Name. I would like to basically have one stored procedure for updating and one for creating. However to do this I will need to be able to convert the actual name of a variable, not the value, to a string. Question 1: Is it possible to do this in T-SQL, and if so how? Question 2: Are there any major drawbacks to using something like this (like performance or CPU usage)? I know if a value is not valid then it will only prevent the update involving that variable and any subsequent ones, but all the data is validated in the vb.net code anyway so will always be valid on submitting to the database, and I will ensure that only variables where the column exists are able to be submitted. Many thanks in advance, Regards, Richard Clarke Edit: I know about using SQL strings and the risk of SQL injection attacks - I studied this a bit in my dissertation a few weeks ago. Basically the website uses an object oriented architecture. There are many classes - for example Product - which have many "Attributes" (I created my own class called Attribute, which has properties such as DataField, Name and Value where DataField is used to get or update data, Name is displayed on the administration frontend when creating or updating a Product and the Value, which may be displayed on the customer frontend, is set by the administrator. DataField is the field I will be using in the "UPDATE Blah SET @Field = @Value". I know this is probably confusing but its really complicated to explain - I have a really good understanding of the entire system in my head but I cant put it into words easily. Basically the structure is set up such that no user will be able to change the value of DataField or Name, but they can change Value. I think if I were to use dynamic parameterised SQL strings there will therefore be no risk of SQL injection attacks. I mean basically loop through all the attributes so that it ends up like: UPDATE Products SET [Name] = '@Name', Description = '@Description', Display = @Display Then loop through all the attributes again and add the parameter values - this will have the same effect as using stored procedures, right?? I dont mind adding to the page load time since this is mainly going to affect the administration frontend, and will marginly affect the customer frontend.

  Read the article

• NSString stringWithFormat swizzled to allow missing format numbered args

  - by coneybeare

  Based on this SO question asked a few hours ago, I have decided to implement a swizzled method that will allow me to take a formatted NSString as the format arg into stringWithFormat, and have it not break when omitting one of the numbered arg references (%1$@, %2$@) I have it working, but this is the first copy, and seeing as this method is going to be potentially called hundreds of thousands of times per app run, I need to bounce this off of some experts to see if this method has any red flags, major performance hits, or optimizations #define NUMARGS(...) (sizeof((int[]){__VA_ARGS__})/sizeof(int)) @implementation NSString (UAFormatOmissions) + (id)uaStringWithFormat:(NSString *)format, ... { if (format != nil) { va_list args; va_start(args, format); // $@ is an ordered variable (%1$@, %2$@...) if ([format rangeOfString:@"$@"].location == NSNotFound) { //call apples method NSString *s = [[[NSString alloc] initWithFormat:format arguments:args] autorelease]; va_end(args); return s; } NSMutableArray *newArgs = (NSMutableArray *)[NSMutableArray arrayWithCapacity:NUMARGS(args)]; id arg = nil; int i = 1; while (arg = va_arg(args, id)) { NSString *f = (NSString *)[NSString stringWithFormat:@"%%%d\$\@", i]; i++; if ([format rangeOfString:f].location == NSNotFound) continue; else [newArgs addObject:arg]; } va_end(args); char *newArgList = (char *)malloc(sizeof(id) * [newArgs count]); [newArgs getObjects:(id *)newArgList]; NSString* result = [[[NSString alloc] initWithFormat:format arguments:newArgList] autorelease]; free(newArgList); return result; } return nil; } The basic algorithm is: search the format string for the %1$@, %2$@ variables by searching for %@ if not found, call the normal stringWithFormat and return else, loop over the args if the format has a position variable (%i$@) for position i, add the arg to the new arg array else, don't add the arg take the new arg array, convert it back into a va_list, and call initWithFormat:arguments: to get the correct string. The idea is that I would run all [NSString stringWithFormat:] calls through this method instead. This might seem unnecessary to many, but click on to the referenced SO question (first line) to see examples of why I need to do this. Ideas? Thoughts? Better implementations? Better Solutions?

  Read the article

• WPF DataTemplates with VS2010 designer support + reusable - would you do it that way?

  - by Christian

  Ok, I am currently tidying up all my old stuff. I ran into the issue of "code only DataTemplates" - which are really a pain in the ass. You can't see anything, they are really hard to design, and I want to improve my project. So I had the idea to use the following solution. The main benefits are: You have designer support for your data template You can easily include example sample data The file naming is consistent and easy to remember The preview does not require an additional XAML wrapper (even with code only controls) I will try to explain and illustrate my solution using a few pictures. I am interested in feedback, especially if you can imagine a better way to do it. And, of course, if you see any maintenance or performance issues. Ok, lets start with a simple PreviewObject. I want to have some data in it, so I create a subclass which will automatically fill in some dummy data. Then I add a list to the control, and name this list. Afterwards I add a DataTemplate, this is the sole reason for the whole control (to be able to see and edit the DataTemplate in place): Now I use this control to get my DataTemplate, to use it in other places. To make this easier, I added some code in the code behind, see here: Now I want a control to show me a list of PreviewItems, so I created a "code-only" control which creates an instance of my service (or gets one using DI in real world) and fills its list box with it: To view the result of this work, I added this control inside the same named XAML, this is basically only to be able to see the final result: What I do not like in this solution: The need to create the last control in "code only". So I tried something different while writing this post. The following two screenshots illustrate the approach. I am creating an instance of the service inside the DataContext, and I am using bindings to supply the Itemssourc and the ItemTemplate. The reason for the strange "static property" is refactoring support. If I hardcode the path in the designer (e.g. using "Path = PreviewHistory") and I refactor the names (which happens quite often, early design phase) - I screw up my controls without realizing it. Does anyone has a better idea for this? I am using Resharper, btw. Thanks for any input, and sorry for the image overkill. Just easier to explain that way.. Chris

  Read the article

• "ResolveAssemblyReference" task fails and System.BadImageFormatException, but assembly isn't used an

  - by bdwakefield

  I am getting an error about the assembly "C:\Ora10g\bin\Zip.exe". The trouble is this solution does NOT use anything in Oracle at all. I could not find a single reference to 10g anywhere in the project. I inherited this from another person who left our group. He never had this issue. Another member of my team said he got this before but reinstalling the client portion of 10g fixed it. No such luck there. I even tried using WinGrep to search the entire solution folder for "Ora10g" but it wasn't there. Any ideas? I can't build this solution until I can figure out how to get rid of this false reference to Oracle. VS 2005 solution. Contains a couple WinForm apps, a couple class libraries, and a web service. The error occurs in the main class library project. Here is the error message: Error 1 The "ResolveAssemblyReference" task failed unexpectedly. System.BadImageFormatException: Could not load file or assembly 'C:\Ora10g\bin\Zip.exe' or one of its dependencies. The module was expected to contain an assembly manifest. File name: 'C:\Ora10g\bin\Zip.exe' at System.Reflection.AssemblyName.nGetFileInformation(String s) at System.Reflection.AssemblyName.GetAssemblyName(String assemblyFile) at Microsoft.Build.Shared.AssemblyNameExtension.GetAssemblyNameEx(String path) at Microsoft.Build.Tasks.SystemState.GetAssemblyName(String path) at Microsoft.Build.Tasks.Resolver.FileMatchesAssemblyName(AssemblyNameExtension assemblyName, Boolean isPrimaryProjectReference, Boolean wantSpecificVersion, Boolean allowMismatchBetweenFusionNameAndFileName, String pathToCandidateAssembly, ResolutionSearchLocation searchLocation) at Microsoft.Build.Tasks.Resolver.ResolveAsFile(String fullPath, AssemblyNameExtension assemblyName, Boolean isPrimaryProjectReference, Boolean wantSpecificVersion, Boolean allowMismatchBetweenFusionNameAndFileName, ArrayList assembliesConsideredAndRejected) at Microsoft.Build.Tasks.Resolver.ResolveFromDirectory(AssemblyNameExtension assemblyName, Boolean isPrimaryProjectReference, Boolean wantSpecificVersion, String[] executableExtensions, String directory, ArrayList assembliesConsideredAndRejected) at Microsoft.Build.Tasks.AssemblyFoldersResolver.Resolve(AssemblyNameExtension assemblyName, String rawFileNameCandidate, Boolean isPrimaryProjectReference, Boolean wantSpecificVersion, String[] executableExtensions, String hintPath, String assemblyFolderKey, ArrayList assembliesConsideredAndRejected, String& foundPath, Boolean& userRequestedSpecificFile) at Microsoft.Build.Tasks.AssemblyResolution.ResolveReference(IEnumerable`1 jaggedResolvers, AssemblyNameExtension assemblyName, String rawFileNameCandidate, Boolean isPrimaryProjectReference, Boolean wantSpecificVersion, String[] executableExtensions, String hintPath, String assemblyFolderKey, ArrayList assembliesConsideredAndRejected, String& resolvedSearchPath, Boolean& userRequestedSpecificFile) at Microsoft.Build.Tasks.ReferenceTable.ResolveReference(AssemblyNameExtension assemblyName, String rawFileNameCandidate, Reference reference) at Microsoft.Build.Tasks.ReferenceTable.ResolveAssemblyFilenames() at Microsoft.Build.Tasks.ReferenceTable.ComputeClosure() at Microsoft.Build.Tasks.ReferenceTable.ComputeClosure(DependentAssembly[] remappedAssembliesValue, ITaskItem[] referenceAssemblyFiles, ITaskItem[] referenceAssemblyNames, ArrayList exceptions) at Microsoft.Build.Tasks.ResolveAssemblyReference.Execute(FileExists fileExists, DirectoryExists directoryExists, GetDirectories getDirectories, GetAssemblyName getAssemblyName, GetAssemblyMetadata getAssemblyMetadata, GetRegistrySubKeyNames getRegistrySubKeyNames, GetRegistrySubKeyDefaultValue getRegistrySubKeyDefaultValue, GetLastWriteTime getLastWriteTime) at Microsoft.Build.Tasks.ResolveAssemblyReference.Execute() at Microsoft.Build.BuildEngine.TaskEngine.ExecuteTask(ExecutionMode howToExecuteTask, Hashtable projectItemsAvailableToTask, BuildPropertyGroup projectPropertiesAvailableToTask, Boolean& taskClassWasFound) WRN: Assembly binding logging is turned OFF. To enable assembly bind failure logging, set the registry value [HKLM\Software\Microsoft\Fusion!EnableLog] (DWORD) to 1. Note: There is some performance penalty associated with assembly bind failure logging. To turn this feature off, remove the registry value [HKLM\Software\Microsoft\Fusion!EnableLog].

  Read the article

• Facing Memory Leaks in AES Encryption Method.

  - by Mubashar Ahmad

  Can anyone please identify is there any possible memory leaks in following code. I have tried with .Net Memory Profiler and it says "CreateEncryptor" and some other functions are leaving unmanaged memory leaks as I have confirmed this using Performance Monitors. but there are already dispose, clear, close calls are placed wherever possible please advise me accordingly. its a been urgent. public static string Encrypt(string plainText, string key) { //Set up the encryption objects byte[] encryptedBytes = null; using (AesCryptoServiceProvider acsp = GetProvider(Encoding.UTF8.GetBytes(key))) { byte[] sourceBytes = Encoding.UTF8.GetBytes(plainText); using (ICryptoTransform ictE = acsp.CreateEncryptor()) { //Set up stream to contain the encryption using (MemoryStream msS = new MemoryStream()) { //Perform the encrpytion, storing output into the stream using (CryptoStream csS = new CryptoStream(msS, ictE, CryptoStreamMode.Write)) { csS.Write(sourceBytes, 0, sourceBytes.Length); csS.FlushFinalBlock(); //sourceBytes are now encrypted as an array of secure bytes encryptedBytes = msS.ToArray(); //.ToArray() is important, don't mess with the buffer csS.Close(); } msS.Close(); } } acsp.Clear(); } //return the encrypted bytes as a BASE64 encoded string return Convert.ToBase64String(encryptedBytes); } private static AesCryptoServiceProvider GetProvider(byte[] key) { AesCryptoServiceProvider result = new AesCryptoServiceProvider(); result.BlockSize = 128; result.KeySize = 256; result.Mode = CipherMode.CBC; result.Padding = PaddingMode.PKCS7; result.GenerateIV(); result.IV = new byte[] { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 }; byte[] RealKey = GetKey(key, result); result.Key = RealKey; // result.IV = RealKey; return result; } private static byte[] GetKey(byte[] suggestedKey, SymmetricAlgorithm p) { byte[] kRaw = suggestedKey; List<byte> kList = new List<byte>(); for (int i = 0; i < p.LegalKeySizes[0].MaxSize; i += 8) { kList.Add(kRaw[(i / 8) % kRaw.Length]); } byte[] k = kList.ToArray(); return k; }

  Read the article

• java.lang.ClassNotFoundException: org.apache.struts2.dispatcher.FilterDispatcher

  - by user714698

  log when start the tomcat Apr 28, 2011 10:52:57 AM org.apache.catalina.core.AprLifecycleListener init INFO: The APR based Apache Tomcat Native library which allows optimal performance in production environments was not found on the java.library.path: D:\software\jdk1.5.0_06\bin;.;C:\WINDOWS\system32;C:\WINDOWS;D:/software/jdk1.5.0_06/bin/../jre/bin/client;D:/software/jdk1.5.0_06/bin/../jre/bin;C:\WINDOWS\system32;C:\WINDOWS;C:\WINDOWS\System32\Wbem;C:\Program Files\TortoiseSVN\bin.;D:\software\jdk1.5.0_06\bin;D:\software\Ant 1.7\bin;D:\software\Axis2-1.5.4\axis2-1.5.4-bin\axis2-1.5.4\bin;C:\Program Files\IDM Computer Solutions\UltraEdit\ Apr 28, 2011 10:52:58 AM org.apache.tomcat.util.digester.SetPropertiesRule begin WARNING: [SetPropertiesRule]{Server/Service/Engine/Host/Context} Setting property 'source' to 'org.eclipse.jst.jee.server:StrutsHelloWorld' did not find a matching property. Apr 28, 2011 10:52:58 AM org.apache.tomcat.util.digester.SetPropertiesRule begin WARNING: [SetPropertiesRule]{Server/Service/Engine/Host/Context} Setting property 'source' to 'org.eclipse.jst.jee.server:StrutsHelloWorld1' did not find a matching property. Apr 28, 2011 10:53:00 AM org.apache.coyote.http11.Http11Protocol init INFO: Initializing Coyote HTTP/1.1 on http-8080 Apr 28, 2011 10:53:00 AM org.apache.catalina.startup.Catalina load INFO: Initialization processed in 3657 ms Apr 28, 2011 10:53:00 AM org.apache.catalina.core.StandardService start INFO: Starting service Catalina Apr 28, 2011 10:53:00 AM org.apache.catalina.core.StandardEngine start INFO: Starting Servlet Engine: Apache Tomcat/6.0.32 Apr 28, 2011 10:53:01 AM org.apache.catalina.core.StandardContext filterStart SEVERE: Exception starting filter struts2 java.lang.ClassNotFoundException: org.apache.struts2.dispatcher.FilterDispatcher at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1680) at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1526) at org.apache.catalina.core.ApplicationFilterConfig.getFilter(ApplicationFilterConfig.java:269) at org.apache.catalina.core.ApplicationFilterConfig.setFilterDef(ApplicationFilterConfig.java:422) at org.apache.catalina.core.ApplicationFilterConfig.<init>(ApplicationFilterConfig.java:115) at org.apache.catalina.core.StandardContext.filterStart(StandardContext.java:4071) at org.apache.catalina.core.StandardContext.start(StandardContext.java:4725) at org.apache.catalina.core.ContainerBase.start(ContainerBase.java:1053) at org.apache.catalina.core.StandardHost.start(StandardHost.java:840) at org.apache.catalina.core.ContainerBase.start(ContainerBase.java:1053) at org.apache.catalina.core.StandardEngine.start(StandardEngine.java:463) at org.apache.catalina.core.StandardService.start(StandardService.java:525) at org.apache.catalina.core.StandardServer.start(StandardServer.java:754) at org.apache.catalina.startup.Catalina.start(Catalina.java:595) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) at java.lang.reflect.Method.invoke(Method.java:585) at org.apache.catalina.startup.Bootstrap.start(Bootstrap.java:289) at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:414) Apr 28, 2011 10:53:01 AM org.apache.catalina.core.StandardContext start SEVERE: Error filterStart Apr 28, 2011 10:53:01 AM org.apache.catalina.core.StandardContext start SEVERE: Context [/StrutsHelloWorld1] startup failed due to previous errors log4j:WARN No appenders could be found for logger (com.opensymphony.xwork2.config.providers.XmlConfigurationProvider). log4j:WARN Please initialize the log4j system properly. Apr 28, 2011 10:53:05 AM org.apache.coyote.http11.Http11Protocol start INFO: Starting Coyote HTTP/1.1 on http-8080 Apr 28, 2011 10:53:05 AM org.apache.jk.common.ChannelSocket init INFO: JK: ajp13 listening on /0.0.0.0:8009 Apr 28, 2011 10:53:05 AM org.apache.jk.server.JkMain start INFO: Jk running ID=0 time=0/46 config=null Apr 28, 2011 10:53:05 AM org.apache.catalina.startup.Catalina start INFO: Server startup in 4951 ms

  Read the article

• Adding unique objects to Core Data

  - by absolut

  I'm working on an iPhone app that gets a number of objects from a database. I'd like to store these using Core Data, but I'm having problems with my relationships. A Detail contains any number of POIs (points of interest). When I fetch a set of POI's from the server, they contain a detail ID. In order to associate the POI with the Detail (by ID), my process is as follows: Query the ManagedObjectContext for the detailID. If that detail exists, add the poi to it. If it doesn't, create the detail (it has other properties that will be populated lazily). The problem with this is performance. Performing constant queries to Core Data is slow, to the point where adding a list of 150 POI's takes a minute thanks to the multiple relationships involved. In my old model, before Core Data (various NSDictionary cache objects) this process was super fast (look up a key in a dictionary, then create it if it doesn't exist) I have more relationships than just this one, but pretty much every one has to do this check (some are many to many, and they have a real problem). Does anyone have any suggestions for how I can help this? I could perform fewer queries (by searching for a number of different ID's), but I'm not sure how much this will help. Some code: POI *poi = [NSEntityDescription insertNewObjectForEntityForName:@"POI" inManagedObjectContext:[(AppDelegate*)[UIApplication sharedApplication].delegate managedObjectContext]]; poi.POIid = [attributeDict objectForKey:kAttributeID]; poi.detailId = [attributeDict objectForKey:kAttributeDetailID]; Detail *detail = [self findDetailForID:poi.POIid]; if(detail == nil) { detail = [NSEntityDescription insertNewObjectForEntityForName:@"Detail" inManagedObjectContext:[(AppDelegate*)[UIApplication sharedApplication].delegate managedObjectContext]]; detail.title = poi.POIid; detail.subtitle = @""; detail.detailType = [attributeDict objectForKey:kAttributeType]; } -(Detail*)findDetailForID:(NSString*)detailID { NSManagedObjectContext *moc = [[UIApplication sharedApplication].delegate managedObjectContext]; NSEntityDescription *entityDescription = [NSEntityDescription entityForName:@"Detail" inManagedObjectContext:moc]; NSFetchRequest *request = [[[NSFetchRequest alloc] init] autorelease]; [request setEntity:entityDescription]; NSPredicate *predicate = [NSPredicate predicateWithFormat: @"detailid == %@", detailID]; [request setPredicate:predicate]; NSLog(@"%@", [predicate description]); NSError *error; NSArray *array = [moc executeFetchRequest:request error:&error]; if (array == nil || [array count] != 1) { // Deal with error... return nil; } return [array objectAtIndex:0]; }

  Read the article

• Is it normal for a programmer with 2 years experience to take a long time to code simple programs?

  - by ajax81

  Hi all, I'm a relatively new programmer (18 months on the scene), and I'm finally getting to the point where I'm comfortable accepting projects and developing solutions under minimal supervision. Unfortunately, this also means that I've become acutely aware of my performance shortfalls, the most prevalent of which is the amount of time it takes me to develop, test, and submit algorithms for review. A great example of what I'm talking about occurred this week when I was tasked with developing a simple XML web service (asp.net 3.5) callable via client-side JavaScript, that accepts a single parameter and returns a dataset output to a modal window (please note this is the first time I've had to develop a web service and have had ZERO experience creating/consuming them...let alone calling them from JS client side). Keeping a long story short -- I worked on it for 4 days straight, all day each day, for a grand total of 36 hours, not including the time I spent dwelling on the problem in the shower, the morning commute, and laying awake in bed at night. I learned a great deal about web services and xml/json/javascript...but was called in for a management review to discuss the length of time it took me to develop the solution. In the meeting, I was praised for the quality of my work and was in fact told that my effort was commendable. However, they (senior leads and pm's) weren't impressed with the amount of time it took me to develop the solution and expressed that they would have liked to see the solution in roughly 1/3 of the time it took me. I guess what concerns me the most is that I've identified this pattern as common for myself. Between online videos, book research, and trial/error coding...if its something I haven't seen before, I can spend up to two weeks on a problem that seems to only take the pros in the videos moments to code up. And of course, knowing that management isn't happy with this pattern has shaken me up a bit. To sum up, I have some very specific questions I'd like to ask, and would greatly appreciate your objective professional feedback. Is my experience as a junior programmer common among new developers? Or is it possible that I'm just not cut out for the work? If you suspect that my experience is not common and that there may be an aptitude issue, do you have any suggestions/solutions that I could propose to management to help bring me up to speed? Do seasoned, professional programmers ever encounter knowledge barriers that considerably delay deliverables? When you started out in the industry, did you know how to "do it all"? If not, how long did it take you to be perceived as "proficient"? Was it a natural progression of trial and error, or was there a particular zen moment when you knew you had achieved super saiyen power level? Anyways, thanks for taking the time to read my question(s). I don't know if this is the right place to ask for professional career guidance, but I greatly appreciate your willingness to help me out. Cheers, Daniel

  Read the article

• Floating point vs integer calculations on modern hardware

  - by maxpenguin

  I am doing some performance critical work in C++, and we are currently using integer calculations for problems that are inherently floating point because "its faster". This causes a whole lot of annoying problems and adds a lot of annoying code. Now, I remember reading about how floating point calculations were so slow approximately circa the 386 days, where I believe (IIRC) that there was an optional co-proccessor. But surely nowadays with exponentially more complex and powerful CPUs it makes no difference in "speed" if doing floating point or integer calculation? Especially since the actual calculation time is tiny compared to something like causing a pipeline stall or fetching something from main memory? I know the correct answer is to benchmark on the target hardware, what would be a good way to test this? I wrote two tiny C++ programs and compared their run time with "time" on Linux, but the actual run time is too variable (doesn't help I am running on a virtual server). Short of spending my entire day running hundreds of benchmarks, making graphs etc. is there something I can do to get a reasonable test of the relative speed? Any ideas or thoughts? Am I completely wrong? The programs I used as follows, they are not identical by any means: #include <iostream> #include <cmath> #include <cstdlib> #include <time.h> int main( int argc, char** argv ) { int accum = 0; srand( time( NULL ) ); for( unsigned int i = 0; i < 100000000; ++i ) { accum += rand( ) % 365; } std::cout << accum << std::endl; return 0; } Program 2: #include <iostream> #include <cmath> #include <cstdlib> #include <time.h> int main( int argc, char** argv ) { float accum = 0; srand( time( NULL ) ); for( unsigned int i = 0; i < 100000000; ++i ) { accum += (float)( rand( ) % 365 ); } std::cout << accum << std::endl; return 0; } Thanks in advance!

  Read the article

• Eclipselink read complex oject model in an ordered way

  - by Raven

  Hi, I need to read a complex model in an ordered way with eclipselink. The order is mandantory because it is a huge database and I want to have an output of a small portion of the database in a jface tableview. Trying to reorder it in the loading/quering thread takes too long and ordering it in the LabelProvider blocks the UI thread too much time, so I thought if Eclipselink could be used that way, that the database will order it, it might give me the performance I need. Unfortunately the object model can not be changed :-( The model is something like: @SuppressWarnings("serial") @Entity public class Thing implements Serializable { @Id @GeneratedValue(strategy = GenerationType.TABLE) private int id; private String name; @OneToMany(cascade=CascadeType.ALL) @PrivateOwned private List<Property> properties = new ArrayList<Property>(); ... // getter and setter following here } public class Property implements Serializable { @Id @GeneratedValue(strategy = GenerationType.TABLE) private int id; @OneToOne private Item item; private String value; ... // getter and setter following here } public class Item implements Serializable { @Id @GeneratedValue(strategy = GenerationType.TABLE) private int id; private String name; .... // getter and setter following here } // Code end In the table view the y-axis is more or less created with the query Query q = em.createQuery("SELECT m FROM Thing m ORDER BY m.name ASC"); using the "name" attribute from the Thing objects as label. In the table view the x-axis is more or less created with the query Query q = em.createQuery("SELECT m FROM Item m ORDER BY m.name ASC"); using the "name" attribute from the Item objects as label. Each cell has the value Things.getProperties().get[x].getValue() Unfortunately the list "properties" is not ordered, so the combination of cell value and x-axis column number (x) is not necessarily correct. Therefore I need to order the list "properties" in the same way as I ordered the labeling of the x-axis. And exactly this is the thing I dont know how it is done. So querying for the Thing objects should return the list "properties" "ORDER BY name ASC" but of the "Item"s objects. My ideas are something like having a query with two JOINs. Joing Things with Property and with Item but somehow I was unable to get it to work yet. Thank you for your help and your ideas to solve this riddle.

  Read the article

• What are five things you hate about your favorite language?

  - by brian d foy

  There's been a cluster of Perl-hate on Stackoverflow lately, so I thought I'd bring my "Five things you hate about your favorite language" question to StackOverflow. Take your favorite language and tell me five things you hate about it. Those might be things that just annoy you, admitted design flaws, recognized performance problems, or any other category. You just have to hate it, and it has to be your favorite language. Don't compare it to another language, and don't talk about languages that you already hate. Don't talk about the things you like in your favorite language. I just want to hear the things that you hate but tolerate so you can use all of the other stuff, and I want to hear it about the language you wished other people would use. I ask this whenever someone tries to push their favorite language on me, and sometimes as an interview question. If someone can't find five things to hate about his favorite tool, he don't know it well enough to either advocate it or pull in the big dollars using it. He hasn't used it in enough different situations to fully explore it. He's advocating it as a culture or religion, which means that if I don't choose his favorite technology, I'm wrong. I don't care that much which language you use. Don't want to use a particular language? Then don't. You go through due diligence to make an informed choice and still don't use it? Fine. Sometimes the right answer is "You have a strong programming team with good practices and a lot of experience in Bar. Changing to Foo would be stupid." This is a good question for code reviews too. People who really know a codebase will have all sorts of suggestions for it, and those who don't know it so well have non-specific complaints. I ask things like "If you could start over on this project, what would you do differently?" In this fantasy land, users and programmers get to complain about anything and everything they don't like. "I want a better interface", "I want to separate the model from the view", "I'd use this module instead of this other one", "I'd rename this set of methods", or whatever they really don't like about the current situation. That's how I get a handle on how much a particular developer knows about the codebase. It's also a clue about how much of the programmer's ego is tied up in what he's telling me. Hate isn't the only dimension of figuring out how much people know, but I've found it to be a pretty good one. The things that they hate also give me a clue how well they are thinking about the subject.

  Read the article

• Am I Leaking ADO.NET Connections?

  - by HardCode

  Here is an example of my code in a DAL. All calls to the database's Stored Procedures are structured this way, and there is no in-line SQL. Friend Shared Function Save(ByVal s As MyClass) As Boolean Dim cn As SqlClient.SqlConnection = Dal.Connections.MyAppConnection Dim cmd As New SqlClient.SqlCommand Try cmd.Connection = cn cmd.CommandType = CommandType.StoredProcedure cmd.CommandText = "proc_save_my_class" cmd.Parameters.AddWithValue("@param1", s.Foo) cmd.Parameters.AddWithValue("@param2", s.Bar) Return True Finally Dal.Utility.CleanupAdoObjects(cmd, cn) End Try End Function Here is the Connection factory (if I am using the correct term): Friend Shared Function MyAppConnection() As SqlClient.SqlConnection Dim cn As New SqlClient.SqlConnection(ConfigurationManager.ConnectionStrings("MyConnectionString").ToString) cn.Open() If cn.State <> ConnectionState.Open Then ' CriticalException is a custom object inheriting from Exception. Throw New CriticalException("Could not connect to the database.") Else Return cn End If End Function Here is the Dal.Utility.CleaupAdoObjects() function: Friend Shared Sub CleanupAdoObjects(ByVal cmd As SqlCommand, ByVal cn As SqlConnection) If cmd IsNot Nothing Then cmd.Dispose() If cn IsNot Nothing AndAlso cn.State <> ConnectionState.Closed Then cn.Close() End Sub I am getting a lot of "Timeout expired. The timeout period elapsed prior to completion of the operation or the server is not responding." error messages reported by the users. The application's DAL opens a connection, reads or saves data, and closes it. No connections are ever left open - intentionally! There is nothing obvious on the Windows 2000 Server hosting the SQL Server 2000 that would indicate a problem. Nothing in the Event Logs and nothing in the SQL Server logs. The timeouts happen randomly - I cannot reproduce. It happens early in the day with only 1 to 5 users in the system. It also happens with around 50 users in the system. The most connections to SQL Server via Performance Monitor, for all databases, has been about 74. The timeouts happen in code that both saves to, and reads from, the database in different parts of the application. The stack trace does not point to one or two offending DAL functions. It's happened in many different places. Does my ADO.NET code appear to be able to leak connections? I've goolged around a bit, and I've read that if the connection pool fills up, this can happen. However, I'm not explicitly setting any connection pooling. I've even tried to increase the Connection Timeout in the connection string, but timeouts happen long before the 300 second (5 minute) value: <add name="MyConnectionString" connectionString="Data Source=MyServer;Initial Catalog=MyDatabase;Integrated Security=SSPI;Connection Timeout=300;"/> I'm at a total loss already as to what is causing these Timeout issues. Any ideas are appreciated.

  Read the article

• compiling opencv 2.4 on a 64 bit mac in Xcode

  - by Walt

  I have an opencv project that I've been developing under ubuntu 12.04, on a parellels VM on a mac which has an x86_64 architecture. There have been many screen switching performance issues that I believe are due to the VM, where linux video modes flip around for a couple seconds while camera access is made by the opencv application. I decided to moved the project into Xcode on the mac side of the computer to continue the opencv development. However, I'm not that familiar with xcode and am having trouble getting the project to build correctly there. I have xcode installed. I downloaded and decompressed the latest version of opencv on the mac, and ran: ~/src/opencv/build/cmake-gui -G Xcode .. per the instructions from willowgarage and various other locations. This appeared to work fine (however I'm wondering now if I'm missing an architecture setting in here, although it is 64-bit intel in Xcode). I then setup an xcode project with the source files from the linux project and changed the include directories to use /opt/local/include/... rather than the /usr/local/include/... I switched xcode to use the LLVM GCC compiler in the build settings for the project then set the Apple LLVM Dialog for C++ to Language Dialect to GNU++11 (which seems possibly inconsistant with the line above) I'm not using a makefile in xcode, (that I'm aware of - it has its own project file...) I was also running into a linker issue that looked like they may be resolved with the addition of this linker flag: -lopencv_video based on a similar posting here: other thread however in that case the person was using a Makefile in their project. I've tried adding this linker flag under "Other Linker Flags" in xcode build settings but still get build errors. I think I may have two issues here, one with the architecture settings when building the opencv libraries with Cmake, and one with the linker flag settings in my project. Currently the build error list looks like this: Undefined symbols for architecture x86_64: "cv::_InputArray::_InputArray(cv::Mat const&)", referenced from: _main in main.o "cv::_OutputArray::_OutputArray(cv::Mat&)", referenced from: _main in main.o "cv::Mat::deallocate()", referenced from: cv::Mat::release() in main.o "cv::Mat::copySize(cv::Mat const&)", referenced from: cv::Mat::Mat(cv::Mat const&)in main.o cv::Mat::operator=(cv::Mat const&)in main.o "cv::Mat::Mat(_IplImage const*, bool)", referenced from: _main in main.o "cv::imread(std::basic_string<char, std::char_traits<char>, std::allocator<char> > const&, int)", referenced from: _main in main.o ---SNIP--- ld: symbol(s) not found for architecture x86_64 collect2: ld returned 1 exit status Can anyone provide some guidance on what to try next? Thanks, Walt

  Read the article

• Working with Hibernate Queries

  - by jschoen

  I am new to hibernate queries, and trying to get a grasp on how everything works. I am using Hibernate 3 with Netbeans 6.5. I have a basic project set up and have been playing around with how to do everything. I started with essentially a search query. Where the user can enter values into one or more fields. The table would be Person with the columns first_name, middle_name, last_name for the sake of the example. The first way I found was to have a method that took firstName, middleName, and lastName as parameters: Session session = HibernateUtil.getSessionFactory().getCurrentSession(); Transaction tx = session.beginTransaction(); String query = "from Person where (first_name = :firstName or :firstName is null) "+ "and (middle_name = :middleName or :middleName is null) " "and (last_name = :lastname or :lastName is null)"; Query q = session.createQuery(query); q.setString("firstName", firstName); q.setString("middleName", middleName); q.setString("lastName", lastName); List<Person> results = (List<Person>) q.list(); This did not sit well with me, since it seemed like I should not have to write that much, and well, that I was doing it wrong. So I kept digging and found another way: Session session = HibernateUtil.getSessionFactory().getCurrentSession(); Transaction tx = session.beginTransaction(); Criteria crit = session.createCriteria(Person.class); if (firstName != null) { crit.add(Expression.ge("firstName", firstName); } if (middleName != null) { crit.add(Expression.ge("middleName", middleName); } if (lastName != null) { crit.add(Expression.ge("lastName", lastName); } List<Person> results = (List<Person>) crit.list(); So what I am trying to figure out is which way is the preferred way for this type of query? Criteria or Query? Why? I am guessing that Criteria is the preferred way and you should only use Query when you need to write it by hand for performance type reasons. Am I close?

  Read the article

• How can I inject Javascript (including Prototype.js) in other sites without cluttering the global na

  - by Daniel Magliola

  I'm currently on a project that is a big site that uses the Prototype library, and there is already a humongous amount of Javascript code. We're now working on a piece of code that will get "injected" into other people's sites (picture people adding a <script> tag in their sites) which will then run our code and add a bunch of DOM elements and functionality to their site. This will have new pieces of code, and will also reuse a lot of the code that we use on our main site. The problem I have is that it's of course not cool to just add a <script> that will include Prototype in people's pages. If we do that in a page that's already using ANY framework, we're guaranteed to screw everything up. jQuery gives us the option to "rename" the $ object, so it could handle this situation decently, except obviously for the fact that we're not using jQuery, so we'd have to migrate everything. Right now i'm contemplating a number of ugly choices, and I'm not sure what's best... Rewrite everything to use jQuery, with a renamed $ object everywhere. Creating a "new" Prototype library with only the subset we'd be using in "injected" code, and renaming $ to something else. Then again I'd have to adapt the parts of my code that would be shared somehow. Not using a library at all in injected code, to keep it as clean as possible, and rewriting the shared code to use no library at all. This would obviously degenerate into us creating our own frankenstein of a library, which is probably the worst case scenario ever. I'm wondering what you guys think I could do, and also whether there's some magic option that would solve all my problems... For example, do you think I could use something like Caja / Cajita to sandbox my own code and isolate it from the rest of the site, and have Prototype inside of there? Or am I completely missing the point with that? I also read once about a technique for bookmarklets, were you add your code like this: (function() { /* your code */ })(); And then your code is all inside your anonymous function and you haven't touched the global namespace at all. Do you think I could make one file containing: (function() { /* Full Code of the Prototype file here */ /* All my code that will run in the "other" site */ InitializeStuff_CreateDOMElements_AttachEventHandlers(); })(); Would that work? Would it accomplish the objective of not cluttering the global namespace, and not killing the functionality on a site that uses jQuery, for example? Or is Prototype too complex somehow to isolate it like that? (NOTE: I think I know that that would create closures everywhere and that's slower, but I don't care too much about performance, my code is not doing anything that complex)

  Read the article

• Can simple javascript inheritance be simplified even further?

  - by Will

  John Resig (of jQuery fame) provides a concise and elegant way to allow simple JavaScript inheritance. It was so short and sweet, in fact, that it inspired me to try and simplify it even further (see code below). I've modified his original function such that it still passes all his tests and has the potential advantage of: readability (50% less code) simplicity (you don't have to be a ninja to understand it) performance (no extra wrappers around super/base method calls) consistency with C#'s base keyword Because this seems almost too good to be true, I want to make sure my logic doesn't have any fundamental flaws/holes/bugs, or if anyone has additional suggestions to improve or refute the code (perhaps even John Resig could chime in here!). Does anyone see anything wrong with my approach (below) vs. John Resig's original approach? if (!window.Class) { window.Class = function() {}; window.Class.extend = function(members) { var prototype = new this(); for (var i in members) prototype[i] = members[i]; prototype.base = this.prototype; function object() { if (object.caller == null && this.initialize) this.initialize.apply(this, arguments); } object.constructor = object; object.prototype = prototype; object.extend = arguments.callee; return object; }; } And the tests (below) are nearly identical to the original ones except for the syntax around base/super method calls (for the reason enumerated above): var Person = Class.extend( { initialize: function(isDancing) { this.dancing = isDancing; }, dance: function() { return this.dancing; } }); var Ninja = Person.extend( { initialize: function() { this.base.initialize(false); }, dance: function() { return this.base.dance(); }, swingSword: function() { return true; } }); var p = new Person(true); alert("true? " + p.dance()); // => true var n = new Ninja(); alert("false? " + n.dance()); // => false alert("true? " + n.swingSword()); // => true alert("true? " + (p instanceof Person && p instanceof Class && n instanceof Ninja && n instanceof Person && n instanceof Class));

  Read the article

• How Can I create different selectors for accepting new connection in java NIO

  - by Deepak

  I want to write java tcp socket programming using java NIO. Its working fine. But I am using the same selector for accepting reading from and writing to the clients. How Can I create different selectors for accepting new connection in java NIO, reading and writing. Is there any online help. Actually when I am busy in reading or writing my selector uses more iterator. So If more number of clients are connected then performance of accepting new coneection became slow. But I donot want the accepting clients to be slow // Create a selector and register two socket channels Selector selector = null; try { // Create the selector selector = Selector.open(); // Create two non-blocking sockets. This method is implemented in // e173 Creating a Non-Blocking Socket. SocketChannel sChannel1 = createSocketChannel("hostname.com", 80); SocketChannel sChannel2 = createSocketChannel("hostname.com", 80); // Register the channel with selector, listening for all events sChannel1.register(selector, sChannel1.validOps()); sChannel2.register(selector, sChannel1.validOps()); } catch (IOException e) { } // Wait for events while (true) { try { // Wait for an event selector.select(); } catch (IOException e) { // Handle error with selector break; } // Get list of selection keys with pending events Iterator it = selector.selectedKeys().iterator(); // Process each key at a time while (it.hasNext()) { // Get the selection key SelectionKey selKey = (SelectionKey)it.next(); // Remove it from the list to indicate that it is being processed it.remove(); try { processSelectionKey(selKey); } catch (IOException e) { // Handle error with channel and unregister selKey.cancel(); } } } public void processSelectionKey(SelectionKey selKey) throws IOException { // Since the ready operations are cumulative, // need to check readiness for each operation if (selKey.isValid() && selKey.isConnectable()) { // Get channel with connection request SocketChannel sChannel = (SocketChannel)selKey.channel(); boolean success = sChannel.finishConnect(); if (!success) { // An error occurred; handle it // Unregister the channel with this selector selKey.cancel(); } } if (selKey.isValid() && selKey.isReadable()) { // Get channel with bytes to read SocketChannel sChannel = (SocketChannel)selKey.channel(); // See e174 Reading from a SocketChannel } if (selKey.isValid() && selKey.isWritable()) { // Get channel that's ready for more bytes SocketChannel sChannel = (SocketChannel)selKey.channel(); } } Thanks Deepak

  Read the article

• Oracle Schema Design: Seperate Schema with I/O Overhead?

  - by Guru

  We are designing database schema for a new system based on Oracle 11gR1. We have identified a main schema which would have close to 100 tables, these will be accessed from the front end Java application. We have a requirement to audit the values which got changed in close to 50 tables, this has to be done every row. Which means, it is possible that, for a single row in MYSYS.T1 there might be 50 (or more) rows in MYSYS_AUDIT.T1_AUD table. We might be having old values of every column entry and new values available from T1. DBA gave an observation, advising against this method, because he said, separate schema meant an extra I/O for every operation. Basically AUDIT schema would be used only to do some analyse and enter values (thus SELECT and INSERT). Is it true that, "a separate schema means an extra I/O" ? I could not find justification. It appears logical to me, as the AUDIT data should not be tampered with, so a separate schema. Also, we designed a separate schema for archiving some tables from MYSYS. From MYSYS_ARC the table might be backed up into tapes or deleted after sufficient time. Few stats: Few tables (close to 20, 30) in MYSYS schema could grow to around 50M rows. We have asked for a total disk space of 4 TB. MYSYS_AUDIT schema might be having 10 times that of MYSYS but we wont keep them more than 3 months. Questions Given all these, can you suggest me any improvements? Separate schema affects disc I/O? (one extra I/O for every schema ?) Any general suggestions? Figure: +-------------------+ +-------------------+ | MYSYS | | MYSYS_AUDIT | | | | | | 1. T1 | | 1. T1_AUD | | 2. T2 | | 2. T2_AUD | | 3. T3 |--------->| 3. T3_AUD | | 4. T4 |(SELECT, | 4. T4_AUD | | . | INSERT) | . | | . | | . | | . | | . | | 100. T100 | | 50. T50_AUD | +-------------------+ +-------------------+ | | | | |(INSERT) | | | * +-------------------+ | MYSYS_ARC | | | | 1. T1_ARC | | 2. T2_ARC | | 3. T3_ARC | | 4. T4_ARC | | . | | . | | . | | 100. T100_ARC | +-------------------+ Apart from this, we have two more schemas with only read only rights, but mainly they are for adhoc purpose and we dont mind the performance on them.

  Read the article

• How to optimize my PostgreSQL DB for prefix search?

  - by asmaier

  I have a table called "nodes" with roughly 1.7 million rows in my PostgreSQL db =#\d nodes Table "public.nodes" Column | Type | Modifiers --------+------------------------+----------- id | integer | not null title | character varying(256) | score | double precision | Indexes: "nodes_pkey" PRIMARY KEY, btree (id) I want to use information from that table for autocompletion of a search field, showing the user a list of the ten titles having the highest score fitting to his input. So I used this query (here searching for all titles starting with "s") =# explain analyze select title,score from nodes where title ilike 's%' order by score desc; QUERY PLAN ----------------------------------------------------------------------------------------------------------------------- Sort (cost=64177.92..64581.38 rows=161385 width=25) (actual time=4930.334..5047.321 rows=161264 loops=1) Sort Key: score Sort Method: external merge Disk: 5712kB -> Seq Scan on nodes (cost=0.00..46630.50 rows=161385 width=25) (actual time=0.611..4464.413 rows=161264 loops=1) Filter: ((title)::text ~~* 's%'::text) Total runtime: 5260.791 ms (6 rows) This was much to slow for using it with autocomplete. With some information from Using PostgreSQL in Web 2.0 Applications I was able to improve that with a special index =# create index title_idx on nodes using btree(lower(title) text_pattern_ops); =# explain analyze select title,score from nodes where lower(title) like lower('s%') order by score desc limit 10; QUERY PLAN ------------------------------------------------------------------------------------------------------------------------------------------ Limit (cost=18122.41..18122.43 rows=10 width=25) (actual time=1324.703..1324.708 rows=10 loops=1) -> Sort (cost=18122.41..18144.60 rows=8876 width=25) (actual time=1324.700..1324.702 rows=10 loops=1) Sort Key: score Sort Method: top-N heapsort Memory: 17kB -> Bitmap Heap Scan on nodes (cost=243.53..17930.60 rows=8876 width=25) (actual time=96.124..1227.203 rows=161264 loops=1) Filter: (lower((title)::text) ~~ 's%'::text) -> Bitmap Index Scan on title_idx (cost=0.00..241.31 rows=8876 width=0) (actual time=90.059..90.059 rows=161264 loops=1) Index Cond: ((lower((title)::text) ~>=~ 's'::text) AND (lower((title)::text) ~<~ 't'::text)) Total runtime: 1325.085 ms (9 rows) So this gave me a speedup of factor 4. But can this be further improved? What if I want to use '%s%' instead of 's%'? Do I have any chance of getting a decent performance with PostgreSQL in that case, too? Or should I better try a different solution (Lucene?, Sphinx?) for implementing my autocomplete feature?

  Read the article

• LINQ aggregate left join on SQL CE

  - by P Daddy

  What I need is such a simple, easy query, it blows me away how much work I've done just trying to do it in LINQ. In T-SQL, it would be: SELECT I.InvoiceID, I.CustomerID, I.Amount AS AmountInvoiced, I.Date AS InvoiceDate, ISNULL(SUM(P.Amount), 0) AS AmountPaid, I.Amount - ISNULL(SUM(P.Amount), 0) AS AmountDue FROM Invoices I LEFT JOIN Payments P ON I.InvoiceID = P.InvoiceID WHERE I.Date between @start and @end GROUP BY I.InvoiceID, I.CustomerID, I.Amount, I.Date ORDER BY AmountDue DESC The best equivalent LINQ expression I've come up with, took me much longer to do: var invoices = ( from I in Invoices where I.Date >= start && I.Date <= end join P in Payments on I.InvoiceID equals P.InvoiceID into payments select new{ I.InvoiceID, I.CustomerID, AmountInvoiced = I.Amount, InvoiceDate = I.Date, AmountPaid = ((decimal?)payments.Select(P=>P.Amount).Sum()).GetValueOrDefault(), AmountDue = I.Amount - ((decimal?)payments.Select(P=>P.Amount).Sum()).GetValueOrDefault() } ).OrderByDescending(row=>row.AmountDue); This gets an equivalent result set when run against SQL Server. Using a SQL CE database, however, changes things. The T-SQL stays almost the same. I only have to change ISNULL to COALESCE. Using the same LINQ expression, however, results in an error: There was an error parsing the query. [ Token line number = 4, Token line offset = 9,Token in error = SELECT ] So we look at the generated SQL code: SELECT [t3].[InvoiceID], [t3].[CustomerID], [t3].[Amount] AS [AmountInvoiced], [t3].[Date] AS [InvoiceDate], [t3].[value] AS [AmountPaid], [t3].[value2] AS [AmountDue] FROM ( SELECT [t0].[InvoiceID], [t0].[CustomerID], [t0].[Amount], [t0].[Date], COALESCE(( SELECT SUM([t1].[Amount]) FROM [Payments] AS [t1] WHERE [t0].[InvoiceID] = [t1].[InvoiceID] ),0) AS [value], [t0].[Amount] - (COALESCE(( SELECT SUM([t2].[Amount]) FROM [Payments] AS [t2] WHERE [t0].[InvoiceID] = [t2].[InvoiceID] ),0)) AS [value2] FROM [Invoices] AS [t0] ) AS [t3] WHERE ([t3].[Date] >= @p0) AND ([t3].[Date] <= @p1) ORDER BY [t3].[value2] DESC Ugh! Okay, so it's ugly and inefficient when run against SQL Server, but we're not supposed to care, since it's supposed to be quicker to write, and the performance difference shouldn't be that large. But it just doesn't work against SQL CE, which apparently doesn't support subqueries within the SELECT list. In fact, I've tried several different left join queries in LINQ, and they all seem to have the same problem. Even: from I in Invoices join P in Payments on I.InvoiceID equals P.InvoiceID into payments select new{I, payments} generates: SELECT [t0].[InvoiceID], [t0].[CustomerID], [t0].[Amount], [t0].[Date], [t1].[InvoiceID] AS [InvoiceID2], [t1].[Amount] AS [Amount2], [t1].[Date] AS [Date2], ( SELECT COUNT(*) FROM [Payments] AS [t2] WHERE [t0].[InvoiceID] = [t2].[InvoiceID] ) AS [value] FROM [Invoices] AS [t0] LEFT OUTER JOIN [Payments] AS [t1] ON [t0].[InvoiceID] = [t1].[InvoiceID] ORDER BY [t0].[InvoiceID] which also results in the error: There was an error parsing the query. [ Token line number = 2, Token line offset = 5,Token in error = SELECT ] So how can I do a simple left join on a SQL CE database using LINQ? Am I wasting my time?

  Read the article

• Xcache - No different after using it

  - by Charles Yeung

  Hi I have installed Xcache in my site(using xampp), I have tested more then 10 times on several page and the result is same as default(no any cache installed), is it something wrong with the configure? Updated [xcache-common] ;; install as zend extension (recommended), normally "$extension_dir/xcache.so" zend_extension = /usr/local/lib/php/extensions/non-debug-non-zts-xxx/xcache.so zend_extension_ts = /usr/local/lib/php/extensions/non-debug-zts-xxx/xcache.so ;; For windows users, replace xcache.so with php_xcache.dll zend_extension_ts = C:\xampp\php\ext\php_xcache.dll ;; or install as extension, make sure your extension_dir setting is correct ; extension = xcache.so ;; or win32: ; extension = php_xcache.dll [xcache.admin] xcache.admin.enable_auth = On xcache.admin.user = "mOo" ; xcache.admin.pass = md5($your_password) xcache.admin.pass = "" [xcache] ; ini only settings, all the values here is default unless explained ; select low level shm/allocator scheme implemenation xcache.shm_scheme = "mmap" ; to disable: xcache.size=0 ; to enable : xcache.size=64M etc (any size > 0) and your system mmap allows xcache.size = 60M ; set to cpu count (cat /proc/cpuinfo |grep -c processor) xcache.count = 1 ; just a hash hints, you can always store count(items) > slots xcache.slots = 8K ; ttl of the cache item, 0=forever xcache.ttl = 0 ; interval of gc scanning expired items, 0=no scan, other values is in seconds xcache.gc_interval = 0 ; same as aboves but for variable cache xcache.var_size = 4M xcache.var_count = 1 xcache.var_slots = 8K ; default ttl xcache.var_ttl = 0 xcache.var_maxttl = 0 xcache.var_gc_interval = 300 xcache.test = Off ; N/A for /dev/zero xcache.readonly_protection = Off ; for *nix, xcache.mmap_path is a file path, not directory. ; Use something like "/tmp/xcache" if you want to turn on ReadonlyProtection ; 2 group of php won't share the same /tmp/xcache ; for win32, xcache.mmap_path=anonymous map name, not file path xcache.mmap_path = "/dev/zero" ; leave it blank(disabled) or "/tmp/phpcore/" ; make sure it's writable by php (without checking open_basedir) xcache.coredump_directory = "" ; per request settings xcache.cacher = On xcache.stat = On xcache.optimizer = Off [xcache.coverager] ; per request settings ; enable coverage data collecting for xcache.coveragedump_directory and xcache_coverager_start/stop/get/clean() functions (will hurt executing performance) xcache.coverager = Off ; ini only settings ; make sure it's readable (care open_basedir) by coverage viewer script ; requires xcache.coverager=On xcache.coveragedump_directory = "" Thanks you

  Read the article

• What are the benefits of using ORM over XML Serialization/Deserialization?

  - by Tequila Jinx

  I've been reading about NHibernate and Microsoft's Entity Framework to perform Object Relational Mapping against my data access layer. I'm interested in the benefits of having an established framework to perform ORM, but I'm curious as to the performance costs of using it against standard XML Serialization and Deserialization. Right now, I develop stored procedures in Oracle and SQL Server that use XML Types for either input or output parameters and return or shred XML depending on need. I use a custom database command object that uses generics to deserialize the XML results into a specified serializable class. By using a combination of generics, xml (de)serialization and Microsoft's DAAB, I've got a process that's fairly simple to develop against regardless of the data source. Moreover, since I exclusively use Stored Procedures to perform database operations, I'm mostly protected from changes in the data structure. Here's an over-simplified example of what I've been doing. static void main() { testXmlClass test = new test(1); test.Name = "Foo"; test.Save(); } // Example Serializable Class ------------------------------------------------ [XmlRootAttribute("test")] class testXmlClass() { [XmlElement(Name="id")] public int ID {set; get;} [XmlElement(Name="name")] public string Name {set; get;} //create an instance of the class loaded with data. public testXmlClass(int id) { GenericDBProvider db = new GenericDBProvider(); this = db.ExecuteSerializable("myGetByIDProcedure"); } //save the class to the database... public Save() { GenericDBProvider db = new GenericDBProvider(); db.AddInParameter("myInputParameter", DbType.XML, this); db.ExecuteSerializableNonQuery("mySaveProcedure"); } } // Database Handler ---------------------------------------------------------- class GenericDBProvider { public T ExecuteSerializable<T>(string commandText) where T : class { XmlSerializer xml = new XmlSerializer(typeof(T)); // connection and command code is assumed for the purposes of this example. // the final results basically just come down to... return xml.Deserialize(commandResults) as T; } public void ExecuteSerializableNonQuery(string commandText) { // once again, connection and command code is assumed... // basically, just execute the command along with the specified // parameters which have been serialized. } public void AddInParameter(string name, DbType type, object value) { StringWriter w = new StringWriter(); XmlSerializer x = new XmlSerializer(value.GetType()); //handle serialization for serializable classes. if (type == DbType.Xml && (value.GetType() != typeof(System.String))) { x.Serialize(w, value); w.Close(); // store serialized object in a DbParameterCollection accessible // to my other methods. } else { //handle all other parameter types } } } I'm starting a new project which will rely heavily on database operations. I'm very curious to know whether my current practices will be sustainable in a high-traffic situation and whether or not I should consider switching to NHibernate or Microsoft's Entity Framework to perform what essentially seems to boil down to the same thing I'm currently doing. I appreciate any advice you may have.

  Read the article

< Previous Page | 486 487 488 489 490 491 492 493 494 495 496 497  | Next Page >