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  • Figuring Out Memory Leaks without Clang

    - by RoLYroLLs
    I'm trying to see if I can find some leaks myself in Apple's TopSongs app. Can someone help me out in at least one and how to identify what is in the Leaks reports and how I can get an idea on finding them? ie: I got one like this: # Category Event Type Timestamp Address Size Responsible Library Responsible Caller 0 GeneralBlock-448 Malloc 00:02.185 0x3f41220 448 libxml2.2.dylib xmlNewParserCtxt From what I can tell, the method xmlNewParserCtxt is the problem, and it's not releasing an object, hence Malloc. The responsible library tells me it's the libxml2.2.dylib library with the problem, which I can't edit. Am I heading in the right direction? If so, half the leaks are in that library and well, i can't edit that.

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  • Objective-C (iPhone) Memory Management

    - by Steven
    I'm sorry to ask such a simple question, but it's a specific question I've not been able to find an answer for. I'm not a native objective-c programmer, so I apologise if I use any C# terms! If I define an object in test.h @interface test : something { NSString *_testString; } Then initialise it in test.m -(id)init { _testString = [[NSString alloc] initWithString:@"hello"]; } Then I understand that I would release it in dealloc, as every init should have a release -(void)dealloc { [_testString release]; } However, what I need clarification on is what happens if in init, I use one of the shortcut methods for object creation, do I still release it in dealloc? Doesn't this break the "one release for one init" rule? e.g. -(id)init { _testString = [NSString stringWithString:@"hello"]; } Thanks for your helps, and if this has been answered somewhere else, I apologise!! Steven

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  • eclipse and tomcat

    - by Panayiotis Karabassis
    Hi! I am trying to integrate eclipse with tomcat. My system is Debian Lenny and I have installed tomcat from http://tomcat.apache.org/. My problem is that when launching Tomcat from within eclipse I get the following error: SEVERE: StandardServer.await: create[8005]: java.net.SocketException: Invalid argument at java.net.PlainSocketImpl.socketBind(Native Method) at java.net.PlainSocketImpl.bind(PlainSocketImpl.java:365) at java.net.ServerSocket.bind(ServerSocket.java:319) at java.net.ServerSocket.<init>(ServerSocket.java:185) at org.apache.catalina.core.StandardServer.await(StandardServer.java:373) at org.apache.catalina.startup.Catalina.await(Catalina.java:662) at org.apache.catalina.startup.Catalina.start(Catalina.java:614) 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:597) at org.apache.catalina.startup.Bootstrap.start(Bootstrap.java:289) at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:414) Jun 16, 2010 9:54:34 PM org.apache.coyote.http11.Http11Protocol pause INFO: Pausing Coyote HTTP/1.1 on http-8080 Jun 16, 2010 9:54:34 PM org.apache.catalina.connector.Connector pause SEVERE: Protocol handler pause failed java.net.SocketException: Network is unreachable at java.net.PlainSocketImpl.socketConnect(Native Method) at java.net.PlainSocketImpl.doConnect(PlainSocketImpl.java:333) at java.net.PlainSocketImpl.connectToAddress(PlainSocketImpl.java:195) at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:182) at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:366) at java.net.Socket.connect(Socket.java:529) at java.net.Socket.connect(Socket.java:478) at java.net.Socket.<init>(Socket.java:375) at java.net.Socket.<init>(Socket.java:218) at org.apache.jk.common.ChannelSocket.unLockSocket(ChannelSocket.java:487) at org.apache.jk.common.ChannelSocket.pause(ChannelSocket.java:284) at org.apache.jk.server.JkMain.pause(JkMain.java:725) at org.apache.jk.server.JkCoyoteHandler.pause(JkCoyoteHandler.java:153) at org.apache.catalina.connector.Connector.pause(Connector.java:1029) at org.apache.catalina.core.StandardService.stop(StandardService.java:566) at org.apache.catalina.core.StandardServer.stop(StandardServer.java:744) at org.apache.catalina.startup.Catalina.stop(Catalina.java:648) at org.apache.catalina.startup.Catalina$CatalinaShutdownHook.run(Catalina.java:692) I suspect this is related to the java option java.net.preferIPv4Stack. Thanks in advance!

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  • Problem to display a pdf from my JSF Portlet of Liferay

    - by Stefano
    I use liferay 5.2 with jsf-portlet. From the page I want to press a button to generate one PDF. In managedbean i build pdf and I want to show it in response. In a ByteArrayOutputStream named outputStream i have my pdf built with JasperReport. I write: PortletResponse portletResponse = (PortletResponse)externalCtx.getResponse(); HttpServletResponse httpResponse = PortalUtil.getHttpServletResponse(portletResponse); ServletOutputStream out = httpResponse.getOutputStream(); String filename="Pdf" + System.currentTimeMillis()+".pdf"; httpResponse.reset(); httpResponse.setContentType("application/pdf"); httpResponse.setHeader("Content-Disposition", "attachment; filename=\""+ filename + "\""); httpResponse.setContentLength(outputStream.size()); outputStream.writeTo(out); out.flush(); out.close(); I do not see anything output! In jboss log i read: IllegaStateException.... What is wrong? LOG 11:03:19,716 INFO [STDOUT] 11:03:19,716 ERROR [IncludeTag] Current URL /web/organo-di-governo/datawarehouse?p_p_id=1_WAR_Portlet_Datawarehouse_INSTANCE_D7s7&p_p_lifecycle=1&p_p_state=normal&p_p_mode=view&p_p_col_id=column-2&p_p_col_count=1&_1_WAR_Portlet_Datawarehouse_INSTANCE_D7s7_com.sun.faces.portlet.VIEW_ID=%2Fview.xhtml&_1_WAR_Portlet_Datawarehouse_INSTANCE_D7s7_com.sun.faces.portlet.NAME_SPACE=_1_WAR_Portlet_Datawarehouse_INSTANCE_D7s7_ generates exception: null 11:03:19,717 INFO [STDOUT] 11:03:19,717 ERROR [IncludeTag] java.lang.IllegalStateException at com.liferay.portal.servlet.filters.strip.StripResponse.getWriter(StripResponse.java:85) at org.apache.jasper.runtime.JspWriterImpl.initOut(JspWriterImpl.java:125) at org.apache.jasper.runtime.JspWriterImpl.flushBuffer(JspWriterImpl.java:118) at org.apache.jasper.runtime.JspWriterImpl.write(JspWriterImpl.java:326) at org.apache.jasper.runtime.JspWriterImpl.write(JspWriterImpl.java:342) at org.apache.jasper.runtime.JspWriterImpl.print(JspWriterImpl.java:468) at com.liferay.taglib.util.ThemeUtil.includeVM(ThemeUtil.java:208) at com.liferay.taglib.util.ThemeUtil.include(ThemeUtil.java:68) at com.liferay.taglib.util.IncludeTag.doEndTag(IncludeTag.java:59) at org.apache.jsp.html.common.themes.portal_jsp._jspx_meth_liferay_002dtheme_005finclude_005f1(portal_jsp.java:816) at org.apache.jsp.html.common.themes.portal_jsp._jspx_meth_c_005fotherwise_005f0(portal_jsp.java:788) at org.apache.jsp.html.common.themes.portal_jsp._jspService(portal_jsp.java:724) at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70) at javax.servlet.http.HttpServlet.service(HttpServlet.java:803) at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:373) at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:336) at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:265) at javax.servlet.http.HttpServlet.service(HttpServlet.java:803) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206) 11:03:19,718 ERROR [[jsp]] Servlet.service() for servlet jsp threw exception java.lang.IllegalStateException 11:03:19,719 ERROR [[Main Servlet]] Servlet.service() for servlet Main Servlet threw exception java.lang.IllegalStateException at com.liferay.portal.servlet.filters.strip.StripResponse.getWriter(StripResponse.java:85) at org.apache.jasper.runtime.JspWriterImpl.initOut(JspWriterImpl.java:125) at org.apache.jasper.runtime.JspWriterImpl.flushBuffer(JspWriterImpl.java:118) 11:03:19,722 INFO [STDOUT] 11:03:19,720 ERROR [OpenSSOFilter] org.apache.jasper.JasperException: java.lang.IllegalStateException org.apache.jasper.JasperException: java.lang.IllegalStateException at org.apache.jasper.servlet.JspServletWrapper.handleJspException(JspServletWrapper.java:521) at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:409) at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:336) at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:265) 11:03:19,722 INFO [STDOUT] n.internalDoFilter(ApplicationFilterChain.java:235) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206) at org.jboss.web.tomcat.filters.ReplyHeaderFilter.doFilter(ReplyHeaderFilter.java:96) Caused by: java.lang.IllegalStateException at com.liferay.portal.servlet.filters.strip.StripResponse.getWriter(StripResponse.java:85) at org.apache.jasper.runtime.JspWriterImpl.initOut(JspWriterImpl.java:125) at org.apache.jasper.runtime.JspWriterImpl.flushBuffer(JspWriterImpl.java:118)

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  • Rational Application Developer (RAD) 7.5+ and websphere runtime will not pick up jars from projects

    - by Berlin Brown
    With RAD Version: 7.5.3, Java 1.5. I have a couple of different projects. I needed to break out the java code and turn the *.class files into a jar. So basically, same *.class files I just removed the code and then jarred the class files into a jar. I broke the classes into a jar and then included the jar in the project. And I also did an order/export on the jar so that other projects can see the jar. At this point, ideally my project should not have changed because I am using class files in a jar instead of the java code. When I visit my web application in websphere, I get class not found errors on the classes that are now in the jar. Project Structure: A. Project earApp -- will need the webapp B. Project webapp -- will need the project (no jar files or *.java files are found in this project) C. Project javasrc -- the java source and the NEW JAR file are found here. I don't think websphere is acknowledging the jar. Here is the error: java.lang.NoClassDefFoundError: com.MyApp at java.lang.ClassLoader.defineClassImpl(Native Method) at java.lang.ClassLoader.defineClass(ClassLoader.java:258) at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:151) at com.ibm.ws.classloader.CompoundClassLoader._defineClass(CompoundClassLoader.java:675) at com.ibm.ws.classloader.CompoundClassLoader.findClass(CompoundClassLoader.java:614) at com.ibm.ws.classloader.CompoundClassLoader.loadClass(CompoundClassLoader.java:431) at java.lang.ClassLoader.loadClass(ClassLoader.java:597) at java.lang.Class.getDeclaredMethodsImpl(Native Method) at java.lang.Class.getDeclaredMethods(Class.java:664) at com.ibm.ws.webcontainer.annotation.data.ScannedAnnotationData.collectMethodAnnotations(ScannedAnnotationData.java:130) at com.ibm.ws.webcontainer.annotation.data.ScannedAnnotationData.<init>(ScannedAnnotationData.java:47) at com.ibm.ws.webcontainer.annotation.AnnotationScanner.scanClass(AnnotationScanner.java:61) at com.ibm.ws.wswebcontainer.webapp.WebApp.processRuntimeAnnotationHelpers(WebApp.java:711) at com.ibm.ws.wswebcontainer.webapp.WebApp.populateJavaNameSpace(WebApp.java:624) at com.ibm.ws.wswebcontainer.webapp.WebApp.initialize(WebApp.java:289) at com.ibm.ws.wswebcontainer.webapp.WebGroup.addWebApplication(WebGroup.java:93) at com.ibm.ws.wswebcontainer.VirtualHost.addWebApplication(VirtualHost.java:162) at com.ibm.ws.wswebcontainer.WebContainer.addWebApp(WebContainer.java:671) at com.ibm.ws.wswebcontainer.WebContainer.addWebApplication(WebContainer.java:624) at com.ibm.ws.webcontainer.component.WebContainerImpl.install(WebContainerImpl.java:395) at com.ibm.ws.webcontainer.component.WebContainerImpl.start(WebContainerImpl.java:611) at com.ibm.ws.runtime.component.ApplicationMgrImpl.start(ApplicationMgrImpl.java:1274) at com.ibm.ws.runtime.component.DeployedApplicationImpl.fireDeployedObjectStart(DeployedApplicationImpl.java:1165) at com.ibm.ws.runtime.component.DeployedModuleImpl.start(DeployedModuleImpl.java:587) at com.ibm.ws.runtime.component.DeployedApplicationImpl.start(DeployedApplicationImpl.java:832) at com.ibm.ws.runtime.component.ApplicationMgrImpl.startApplication(ApplicationMgrImpl.java:921) at com.ibm.ws.runtime.component.ApplicationMgrImpl$AppInitializer.run(ApplicationMgrImpl.java:2124) at com.ibm.wsspi.runtime.component.WsComponentImpl$_AsynchInitializer.run(WsComponentImpl.java:342) at com.ibm.ws.util.ThreadPool$Worker.run(ThreadPool.java:1497) What do you think I need to do?

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  • UIIMageView, warning: check_safe_call: could not restore current frame

    - by lukya
    Hi, I am changing the image in UIImageView based on accelerometer input. The images are stored in an array. The application runs fine for a while and then crashes. warning: check_safe_call: could not restore current frame I am not using "UIImage ImageNamed" method when populating the array. The total size of all images is around 12 Mb. But individual images are very light (<100 kb) and i am using only one image at a time from the array. Just in case there are any autoreleases, I have allocated a NSAutoreleasePool in view did load and am draining it in the didReceiveMemoryWarning method (which does get called 2, 3 times before the app crashes?). Following is the code that creates images array: //create autorelease pool as we are creating many autoreleased objects NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init]; NSMutableArray *finalarr = [[NSMutableArray alloc] initWithCapacity:9]; NSLog(@"start loading"); for(int y = 0; y < 100; y+=10) { NSMutableArray *arr = [[NSMutableArray alloc] initWithCapacity:10]; for(int x = 0; x < 10; x++) { NSString *imageName = [[NSString alloc] initWithFormat:@"0%d",y + x]; UIImage *img = [[UIImage alloc] initWithContentsOfFile:[[NSBundle mainBundle] pathForResource:imageName ofType:@"png"]]; [arr addObject:img]; [imageName release]; [img release]; } [finalarr addObject:arr]; [arr release]; } NSLog(@"done loading"); // Override point for customization after app launch viewController.imagesArray = finalarr; [finalarr release]; //retain the array of images [viewController.imagesArray retain]; //release the aurtorelease pool to free memory taken up by objects enqued for release [pool release]; As the app runs smoothly for a while, which means array creation is definitely not the problem. After this the following method is called from [accelerometer didAccelerate] -(BOOL)setImageForX:(int)x andY:(int)y { [self.imageView setImage:(UIImage*)[(NSArray*)[self.imagesArray objectAtIndex:y] objectAtIndex:x]]; return TRUE; } So the only code being executed is the "UIImageView setImage". But no objects are being created here. Please let me know if the code seems to have any leaks or i am doing something wrong. Thanks, Swapnil

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  • spring web application context is not loaded from jar file in WEB-INF/lib when running tomcat in eclipse

    - by Remy J
    I am experimenting with spring, maven, and eclipse but stumbling on a weird issue. I am running Eclipse Helios SR1 with the STS (Spring tools suite) plugin which includes the Maven plugin also. What i want to achieve is a spring mvc webapp which uses an application context loaded from a local application context xml file, but also from other application contexts in jar files dependencies included in WEB-INF/lib. What i'd ultimately like to do is have my persistence layer separated in its own jar file but containing its own spring context files with persistence specific configuration (e.g a jpa entityManagerFactory for example). So to experiment with loading resources from jar dependencies, i created a simple maven project from eclipse, which defines an applicationContext.xml file in src/main/resources Inside, i define a bean <bean id="mybean" class="org.test.MyClass" /> and create the class in the org.test package I run mvn-install from eclipse, which generates me a jar file containing my class and the applicationContext.xml file: testproj.jar |_META-INF |_org |_test |_MyClass.class |_applicationContext.xml I then create a spring mvc project from the Spring template projects provided by STS. I have configured an instance of Tomcat 7.0.8 , and also an instance of springSource tc Server within eclipse. Deploying the newly created project on both servers works without problem. I then add my previous project as a maven dependency of the mvc project. the jar file is correctly added in the Maven Dependencies of the project. In the web.xml that is generated, i now want to load the applicationContext.xml from the jar file as well as the existing one generated for the project. My web.xml now looks like this: org.springframework.web.context.ContextLoaderListener <!-- Processes application requests --> <servlet> <servlet-name>appServlet</servlet-name> <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class> <init-param> <param-name>contextConfigLocation</param-name> <param-value> classpath*:applicationContext.xml, /WEB-INF/spring/appServlet/servlet-context.xml </param-value> </init-param> <load-on-startup>1</load-on-startup> </servlet> <servlet-mapping> <servlet-name>appServlet</servlet-name> <url-pattern>/</url-pattern> </servlet-mapping> Also, in my servlet-context.xml, i have the following: <context:component-scan base-package="org.test" /> <context:component-scan base-package="org.remy.mvc" /> to load classes from the jar spring context (org.test) and to load controllers from the mvc app context. I also change one of my controllers in org.remy.mvc to autowire MyClass to verify that loading the context has worked as intended. public class MyController { @Autowired private MyClass myClass; public void setMyClass(MyClass myClass) { this.myClass = myClass; } public MyClass getMyClass() { return myClass; } [...] } Now this is the weird bit: If i deploy the spring mvc web on my tomcat instance inside eclipse (run on server...) I get the following error : org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'org.springframework.web.servlet.mvc.annotation.DefaultAnnotationHandlerMapping#0': Initialization of bean failed; nested exception is java.lang.NoClassDefFoundError: org/test/MyClass at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:527) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:456) at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:291) at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:222) at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:288) at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:190) at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:580) at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:895) at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:425) at org.springframework.web.servlet.FrameworkServlet.createWebApplicationContext(FrameworkServlet.java:442) at org.springframework.web.servlet.FrameworkServlet.createWebApplicationContext(FrameworkServlet.java:458) at org.springframework.web.servlet.FrameworkServlet.initWebApplicationContext(FrameworkServlet.java:339) at org.springframework.web.servlet.FrameworkServlet.initServletBean(FrameworkServlet.java:306) at org.springframework.web.servlet.HttpServletBean.init(HttpServletBean.java:127) at javax.servlet.GenericServlet.init(GenericServlet.java:160) at org.apache.catalina.core.StandardWrapper.initServlet(StandardWrapper.java:1133) at org.apache.catalina.core.StandardWrapper.loadServlet(StandardWrapper.java:1087) at org.apache.catalina.core.StandardWrapper.load(StandardWrapper.java:996) at org.apache.catalina.core.StandardContext.loadOnStartup(StandardContext.java:4834) at org.apache.catalina.core.StandardContext$3.call(StandardContext.java:5155) at org.apache.catalina.core.StandardContext$3.call(StandardContext.java:5150) at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:303) at java.util.concurrent.FutureTask.run(FutureTask.java:138) at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:885) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:907) at java.lang.Thread.run(Thread.java:619) Caused by: java.lang.NoClassDefFoundError: org/test/MyClass at java.lang.Class.getDeclaredMethods0(Native Method) at java.lang.Class.privateGetDeclaredMethods(Class.java:2427) at java.lang.Class.getDeclaredMethods(Class.java:1791) at org.springframework.util.ReflectionUtils.doWithMethods(ReflectionUtils.java:446) at org.springframework.web.servlet.mvc.annotation.DefaultAnnotationHandlerMapping.determineUrlsForHandlerMethods(DefaultAnnotationHandlerMapping.java:172) at org.springframework.web.servlet.mvc.annotation.DefaultAnnotationHandlerMapping.determineUrlsForHandler(DefaultAnnotationHandlerMapping.java:118) at org.springframework.web.servlet.handler.AbstractDetectingUrlHandlerMapping.detectHandlers(AbstractDetectingUrlHandlerMapping.java:79) at org.springframework.web.servlet.handler.AbstractDetectingUrlHandlerMapping.initApplicationContext(AbstractDetectingUrlHandlerMapping.java:58) at org.springframework.context.support.ApplicationObjectSupport.initApplicationContext(ApplicationObjectSupport.java:119) at org.springframework.web.context.support.WebApplicationObjectSupport.initApplicationContext(WebApplicationObjectSupport.java:72) at org.springframework.context.support.ApplicationObjectSupport.setApplicationContext(ApplicationObjectSupport.java:73) at org.springframework.context.support.ApplicationContextAwareProcessor.invokeAwareInterfaces(ApplicationContextAwareProcessor.java:106) at org.springframework.context.support.ApplicationContextAwareProcessor.postProcessBeforeInitialization(ApplicationContextAwareProcessor.java:85) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.applyBeanPostProcessorsBeforeInitialization(AbstractAutowireCapableBeanFactory.java:394) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1413) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:519) ... 25 more 20-Feb-2011 10:54:53 org.apache.catalina.core.ApplicationContext log SEVERE: StandardWrapper.Throwable org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'org.springframework.web.servlet.mvc.annotation.DefaultAnnotationHandlerMapping#0': Initialization of bean failed; nested exception is java.lang.NoClassDefFoundError: org/test/MyClass If i build the war file (using maven "install" goal), and then deploy that war file in the webapps directory of a standalone tomcat server (7.0.8 as well) it WORKS :-( What am i missing ? Thanks for the help.

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  • Is java HashMap.clear() and remove() memory effective?

    - by Shaman
    Consider the follwing HashMap.clear() code: /** * Removes all of the mappings from this map. * The map will be empty after this call returns. */ public void clear() { modCount++; Entry[] tab = table; for (int i = 0; i < tab.length; i++) tab[i] = null; size = 0; } It seems, that the internal array (table) of Entrys is never shrinked. So, when I add 10000 elements to a map, and after that call map.clear(), it will keep 10000 nulls in it's internal array. So, my question is, how does JVM handle this array of nothing, and thus, is HashMap memory effective?

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  • java.lang.ArrayIndexOutOfBoundsException

    - by thefonso
    Here is the code. import java.applet.Applet; import java.awt.Button; import java.awt.Color; import java.awt.Graphics; import java.awt.event.ActionEvent; import java.awt.event.ActionListener; public class GuessingGame extends Applet{ /** * */ private static final long serialVersionUID = 1L; private final int START_X = 20; private final int START_Y = 40; private final int ROWS = 4; private final int COLS = 4; private final int BOX_WIDTH = 20; private final int BOX_HEIGHT = 20; //this is used to keep track of boxes that have been matched. private boolean matchedBoxes[][]; //this is used to keep track of two boxes that have been clicked. private MaskableBox chosenBoxes[]; private MaskableBox boxes[][]; private Color boxColors[][]; private Button resetButton; public void init() { boxes = new MaskableBox[ROWS][COLS]; boxColors = new Color[ROWS][COLS]; resetButton = new Button("Reset Colors"); resetButton.addActionListener(new ActionListener() { public void actionPerformed(ActionEvent e) { randomizeColors(); buildBoxes(); repaint(); } }); add(resetButton); //separate building colors so we can add a button later //to re-randomize them. randomizeColors(); buildBoxes(); } public void paint(Graphics g) { for (int row =0; row < boxes.length; row ++) { for (int col = 0; col < boxes[row].length; col++) { if(boxes[row][col].isClicked()) { //boxes[row][col].setMaskColor(Color.black); //boxes[row][col].setMask(!boxes[row][col].isMask()); //boxes[row][col].setClicked(false); //} if (!matchedBoxes[row][col]) { gameLogic(boxes[row][col]); //boxes[row][col].draw(g); } } } } //loop through the boxes and draw them. for (int row = 0; row < boxes.length; row++) { for (int col = 0; col < boxes[row].length; col++) { boxes[row][col].draw(g); } } } public void gameLogic(MaskableBox box) { if ((chosenBoxes[0] != null)&&(chosenBoxes[1] != null)) { if(chosenBoxes[0].getBackColor() == chosenBoxes[1].getBackColor()) { for (int i=0; 0 <= chosenBoxes.length; ++i ) { for(int row = 0; row < boxes.length; row++) { for(int col = 0; col < boxes[row].length; col++) { if( boxes[row][col] == chosenBoxes[i] ) { System.out.println("boxes [row][col] == chosenBoxes[] at index: " + i ); matchedBoxes[row][col] = true; break; } } } } }else { chosenBoxes[0].setMask(true); chosenBoxes[1].setMask(true); } chosenBoxes = new MaskableBox[2]; }else { if (chosenBoxes[0] == null) { chosenBoxes[0] = box; chosenBoxes[0].setMask(false); return; }else{ if (chosenBoxes[1] == null) { chosenBoxes[1] = box; chosenBoxes[1].setMask(false); } } } } private void removeMouseListeners() { for(int row = 0; row < boxes.length; row ++) { for(int col = 0; col < boxes[row].length; col++) { removeMouseListener(boxes[row][col]); } } } private void buildBoxes() { // need to clear any chosen boxes when building new array. chosenBoxes = new MaskableBox[2]; // create a new matchedBoxes array matchedBoxes = new boolean [ROWS][COLS]; removeMouseListeners(); for(int row = 0; row < boxes.length; row++) { for(int col = 0; col < boxes[row].length; col++) { boxes[row][col] = new MaskableBox(START_X + col * BOX_WIDTH, START_Y + row * BOX_HEIGHT, BOX_WIDTH, BOX_HEIGHT, Color.gray, boxColors[row][col], true, true, this); addMouseListener(boxes[row][col]); } } } private void randomizeColors() { int[] chosenColors = {0,0,0,0,0,0,0,0}; Color[] availableColors = {Color.red, Color.blue, Color.green, Color.yellow, Color.cyan, Color.magenta, Color.pink, Color.orange }; for(int row = 0; row < boxes.length; row++) { for (int col = 0; col < boxes[row].length; col++) { for (;;) { int rnd = (int) (Math.random() * 8); if (chosenColors[rnd]< 2) { chosenColors[rnd]++; boxColors[row][col] = availableColors[rnd]; break; } } } } } } here is the second batch of code containing maskablebox import java.awt.Color; import java.awt.Container; import java.awt.Graphics; public class MaskableBox extends ClickableBox { private boolean mask; private Color maskColor; Container parent; public MaskableBox(int x, int y, int width, int height, Color borderColor, Color backColor, boolean drawBorder, boolean mask, Container parent ) { super(x, y, width, height, borderColor, backColor, drawBorder, parent); this.parent = parent; this.mask = mask; } public void draw(Graphics g) { if(mask=false) { super.draw(g); // setOldColor(g.getColor()); // g.setColor(maskColor); // g.fillRect(getX(),getY(),getWidth(), getHeight()); // if(isDrawBorder()) { // g.setColor(getBorderColor()); // g.drawRect(getX(),getY(),getWidth(),getHeight()); // } // g.setColor(getOldColor()); }else { if(mask=true) { //super.draw(g); setOldColor(g.getColor()); g.setColor(maskColor); g.fillRect(getX(),getY(),getWidth(), getHeight()); if(isDrawBorder()) { g.setColor(getBorderColor()); g.drawRect(getX(),getY(),getWidth(),getHeight()); } g.setColor(getOldColor()); } } } public boolean isMask() { return mask; } public void setMask(boolean mask) { this.mask = mask; } public Color getMaskColor() { return maskColor; } public void setMaskColor(Color maskColor) { this.maskColor = maskColor; } } I keep getting these error messages. I'm going nuts trying to figure this out. can anyone tell me what I'm doing wrong? boxes [row][col] == chosenBoxes[] at index: 0 boxes [row][col] == chosenBoxes[] at index: 1 Exception in thread "AWT-EventQueue-1" java.lang.ArrayIndexOutOfBoundsException: 2 at GuessingGame.gameLogic(GuessingGame.java:77) at GuessingGame.paint(GuessingGame.java:55) at java.awt.Container.update(Container.java:1801) at sun.awt.RepaintArea.updateComponent(RepaintArea.java:239) at sun.awt.RepaintArea.paint(RepaintArea.java:216) at sun.awt.windows.WComponentPeer.handleEvent(WComponentPeer.java:306) at java.awt.Component.dispatchEventImpl(Component.java:4706) at java.awt.Container.dispatchEventImpl(Container.java:2099) at java.awt.Component.dispatchEvent(Component.java:4460) at java.awt.EventQueue.dispatchEvent(EventQueue.java:599) at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:269) at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:184) at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:174) at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:169) at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:161) at java.awt.EventDispatchThread.run(EventDispatchThread.java:122)

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  • NPE with logging while launching webstart on jre7 update 40

    - by atulsm
    My application was running fine until I upgraded my jre to 7u40. When my application is initializing, it's doing Logger.getLogger("ClassName"), and I'm getting the following exception. java.lang.ExceptionInInitializerError at java.util.logging.Logger.demandLogger(Unknown Source) at java.util.logging.Logger.getLogger(Unknown Source) at com.company.Application.Applet.<clinit>(Unknown Source) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source) at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source) at java.lang.reflect.Method.invoke(Unknown Source) at com.sun.javaws.Launcher.executeApplication(Unknown Source) at com.sun.javaws.Launcher.executeMainClass(Unknown Source) at com.sun.javaws.Launcher.doLaunchApp(Unknown Source) at com.sun.javaws.Launcher.run(Unknown Source) at java.lang.Thread.run(Unknown Source) Caused by: java.lang.NullPointerException at java.util.logging.Logger.setParent(Unknown Source) at java.util.logging.LogManager$6.run(Unknown Source) at java.security.AccessController.doPrivileged(Native Method) at java.util.logging.LogManager.doSetParent(Unknown Source) at java.util.logging.LogManager.access$1100(Unknown Source) at java.util.logging.LogManager$LogNode.walkAndSetParent(Unknown Source) at java.util.logging.LogManager$LoggerContext.addLocalLogger(Unknown Source) at java.util.logging.LogManager$LoggerContext.addLocalLogger(Unknown Source) at java.util.logging.LogManager.addLogger(Unknown Source) at java.util.logging.LogManager$1.run(Unknown Source) at java.security.AccessController.doPrivileged(Native Method) at java.util.logging.LogManager.<clinit>(Unknown Source) The exception is coming from this line: private static Logger logger = Logger.getLogger(Applet.class.getName()); Could it be because of any sideeffects with fix http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=8017174 ? A workaround is to open the java control center and enable logging. This is a concern since by default "Enable Logging" is unchecked. If I select "Enable Logging", the application starts fine.

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  • How to show percentage of 'memory used' in a win32 process?

    - by pj4533
    I know that memory usage is a very complex issue on Windows. I am trying to write a UI control for a large application that shows a 'percentage of memory used' number, in order to give the user an indication that it may be time to clear up some memory, or more likely restart the application. One implementation used ullAvailVirtual from MEMORYSTATUSEX as a base, then used HeapWalk() to walk the process heap looking for additional free memory. The HeapWalk() step was needed because we noticed that after a while of running the memory allocated and freed by the heap was never returned and reported by the ullAvailVirtual number. After hours of intensive working, the ullAvailVirtual number no longer would accurately report the amount of memory available. However, this method proved not ideal, due to occasional odd errors that HeapWalk() would return, even when the process heap was not corrupted. Further, since this is a UI control, the heap walking code was executing every 5-10 seconds. I tried contacting Microsoft about why HeapWalk() was failing, escalated a case via MSDN, but never got an answer other than "you probably shouldn't do that". So, as a second implementation, I used PagefileUsage from PROCESS_MEMORY_COUNTERS as a base. Then I used VirtualQueryEx to walk the virtual address space adding up all regions that weren't MEM_FREE and returned a value for GetMappedFileNameA(). My thinking was that the PageFileUsage was essentially 'private bytes' so if I added to that value the total size of the DLLs my process was using, it would be a good approximation of the amount of memory my process was using. This second method seems to (sorta) work, at least it doesn't cause crashes like the heap walker method. However, when both methods are enabled, the values are not the same. So one of the methods is wrong. So, StackOverflow world...how would you implement this? which method is more promising, or do you have a third, better method? should I go back to the original method, and further debug the odd errors? should I stay away from walking the heap every 5-10 seconds? Keep in mind the whole point is to indicate to the user that it is getting 'dangerous', and they should either free up memory or restart the application. Perhaps a 'percentage used' isn't the best solution to this problem? What is? Another idea I had was a color based system (red, yellow, green, which I could base on more factors than just a single number)

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  • Why is this leaking memory? UIImage `cellForRowAtIndexPath:`

    - by Emil
    Hey. Instruments' Leaks tells me that this UIImage is leaking: UIImage *image = [[UIImage alloc] initWithContentsOfFile:[imagesPath stringByAppendingPathComponent:[NSString stringWithFormat:@"/%@.png", [postsArrayID objectAtIndex:indexPath.row]]]]; // If image contains anything, set cellImage to image. If image is empty, try one more time or use noImage.png, set in IB if (image != nil){ // If image != nil, set cellImage to that image cell.cellImage.image = image; } image = nil; [image release]; (class cell (custom table view cell) also releases cellImage in dealloc method). I haven't got a clue of why it's leaking, but it certainly is. The images gets loaded multiple times in a cellForRowAtIndexPath:-method. The first three cells' image does not leak (130px high, all the space avaliable). Leaks gives me no other info than that a UIImage allocated here in the code leaks. Can you help me figure it out? Thanks :)

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  • String Constant Pool memory sector and garbage collection

    - by WickeD
    I read this question on the site How is the java memory pool divided? and i was wondering to which of these sectors does the "String Constant Pool" belongs? And also does the String literals in the pool ever get GCed? The intern() method returns the base link of the String literal from the pool. If the pool does gets GCed then wouldn't it be counter-productive to the idea of the string pool? New String literals would again be created nullifying the GC. (It is assuming that only a specific set of literals exist in the pool, they never go obsolete and sooner or later they will be needed again)

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  • .NET multithreading, volatile and memory model

    - by fedor-serdukov
    Assume that we have the following code: class Program { static volatile bool flag1; static volatile bool flag2; static volatile int val; static void Main(string[] args) { for (int i = 0; i < 10000 * 10000; i++) { if (i % 500000 == 0) { Console.WriteLine("{0:#,0}",i); } flag1 = false; flag2 = false; val = 0; Parallel.Invoke(A1, A2); if (val == 0) throw new Exception(string.Format("{0:#,0}: {1}, {2}", i, flag1, flag2)); } } static void A1() { flag2 = true; if (flag1) val = 1; } static void A2() { flag1 = true; if (flag2) val = 2; } } } It's fault! The main quastion is Why... I suppose that CPU reorder operations with flag1 = true; and if(flag2) statement, but variables flag1 and flag2 marked as volatile fields...

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  • Implicit Memory Barriers

    - by foo
    let's say i have variables A, B and C that two threads (T1, T2) share. i have the following code: //T1 //~~ A = 1; B = 1; C = 1; InterlockedExchange(ref Foo, 1); //T2 (executes AFTER T1 calls InterlockedExchange) //~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ InterlockedExchange(ref Bar, 1); WriteLine(A); WriteLine(B); WriteLine(C); Question: does calling InterlockedExchange (implicit full fence) on T1 and T2, gurentess that T2 will "See" the write done by T1 before the fence? (A, B and C variables), even though those variables are not plance on the same cache-line as Foo and Bar?

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  • Question about unions and heap allocated memory

    - by Dennis Miller
    I was trying to use a union to so I could update the fields in one thread and then read allfields in another thread. In the actual system, I have mutexes to make sure everything is safe. The problem is with fieldB, before I had to change it fieldB was declared like field A and C. However, due to a third party driver, fieldB must be alligned with page boundary. When I changed field B to be allocated with valloc, I run into problems. Questions: 1) Is there a way to statically declare fieldB alligned on page boundary. Basically do the same thing as valloc, but on the stack? 2) Is it possible to do a union when field B, or any field is being allocated on the heap?. Not sure if that is even legal. Here's a simple Test program I was experimenting with. This doesn't work unless you declare fieldB like field A and C, and make the obvious changes in the public methods. #include <iostream> #include <stdlib.h> #include <string.h> #include <stdio.h> class Test { public: Test(void) { // field B must be alligned to page boundary // Is there a way to do this on the stack??? this->field.fieldB = (unsigned char*) valloc(10); }; //I know this is bad, this class is being treated like //a global structure. Its self contained in another class. unsigned char* PointerToFieldA(void) { return &this->field.fieldA[0]; } unsigned char* PointerToFieldB(void) { return this->field.fieldB; } unsigned char* PointerToFieldC(void) { return &this->field.fieldC[0]; } unsigned char* PointerToAllFields(void) { return &this->allFields[0]; } private: // Is this union possible with field B being // allocated on the heap? union { struct { unsigned char fieldA[10]; //This field has to be alligned to page boundary //Is there way to be declared on the stack unsigned char* fieldB; unsigned char fieldC[10]; } field; unsigned char allFields[30]; }; }; int main() { Test test; strncpy((char*) test.PointerToFieldA(), "0123456789", 10); strncpy((char*) test.PointerToFieldB(), "1234567890", 10); strncpy((char*) test.PointerToFieldC(), "2345678901", 10); char dummy[11]; dummy[10] = '\0'; strncpy(dummy, (char*) test.PointerToFieldA(), 10); printf("%s\n", dummy); strncpy(dummy, (char*) test.PointerToFieldB(), 10); printf("%s\n", dummy); strncpy(dummy, (char*) test.PointerToFieldC(), 10); printf("%s\n", dummy); char allFields[31]; allFields[30] = '\0'; strncpy(allFields, (char*) test.PointerToAllFields(), 30); printf("%s\n", allFields); return 0; }

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  • java oracle syntax error?

    - by murali
    hi, i am using the following code for the uploading keywords & count to the excel file. i am having the keyword_id as primary key for that one i had written sentence...i am having the twocolumns in the excel file..1.keyword 2.count my code is: while (rs.next()) { System.out.println("inside "); String keyword = rs.getString(1); int count = rs.getInt(2); System.out.println("insert into SEARCHABLE_KEYWORDS values ('"+ keyword+"','"+count+"')"); stmtdb.execute("insert into SEARCHABLE_KEYWORDS (keyword_id,keyword,count) values ('"+ "select Searchable_Keywords_sequence.nextval from dual"+ "','"+keyword+"','"+count+"')"); System.out.println(keyword + " " + keyword+" count "+count); } but I am getting the following error: java.sql.SQLException: [Microsoft][ODBC Excel Driver] Too few parameters. Expected 1. at sun.jdbc.odbc.JdbcOdbc.createSQLException(JdbcOdbc.java:6998) at sun.jdbc.odbc.JdbcOdbc.standardError(JdbcOdbc.java:7155) at sun.jdbc.odbc.JdbcOdbc.SQLExecDirect(JdbcOdbc.java:3151) at sun.jdbc.odbc.JdbcOdbcStatement.execute(JdbcOdbcStatement.java:378) at sun.jdbc.odbc.JdbcOdbcStatement.executeQuery(JdbcOdbcStatement.java:284) at keywordsreader.main(keywordsreader.java:42) please help to slove this problem...

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  • Mapping between 4+1 architectural view model & UML

    - by Sadeq Dousti
    I'm a bit confused about how the 4+1 architectural view model maps to UML. Wikipedia gives the following mapping: Logical view: Class diagram, Communication diagram, Sequence diagram. Development view: Component diagram, Package diagram Process view: Activity diagram Physical view: Deployment diagram Scenarios: Use-case diagram The paper Role of UML Sequence Diagram Constructs in Object Lifecycle Concept gives the following mapping: Logical view (class diagram (CD), object diagram (OD), sequence diagram (SD), collaboration diagram (COD), state chart diagram (SCD), activity diagram (AD)) Development view (package diagram, component diagram), Process view (use case diagram, CD, OD, SD, COD, SCD, AD), Physical view (deployment diagram), and Use case view (use case diagram, OD, SD, COD, SCD, AD) which combines the four mentioned above. The web page UML 4+1 View Materials presents the following mapping: Finally, the white paper Applying 4+1 View Architecture with UML 2 gives yet another mapping: Logical view class diagrams, object diagrams, state charts, and composite structures Process view sequence diagrams, communication diagrams, activity diagrams, timing diagrams, interaction overview diagrams Development view component diagrams Physical view deployment diagram Use case view use case diagram, activity diagrams I'm sure further search will reveal other mappings as well. While various people usually have different perspectives, I don't see why this is the case here. Specially, each UML diagram describes the system from a particular aspect. So, for instance, why the "sequence diagram" is considered as describing the "logical view" of the system by one author, while another author considers it as describing the "process view"? Could you please help me clarify the confusion?

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  • SQL SERVER – Weekly Series – Memory Lane – #003

    - by pinaldave
    Here is the list of curetted articles of SQLAuthority.com across all these years. Instead of just listing all the articles I have selected a few of my most favorite articles and have listed them here with additional notes below it. Let me know which one of the following is your favorite article from memory lane. 2006 This was the first year of my blogging and lots of new things I was learning as I go. I was indeed an infant in blogging a few years ago. However, as time passed by I have learned a lot. This year was year of experiments and new learning. 2007 Working as a full time DBA I often encoutered various errors and I started to learn how to avoid those error and document the same. ERROR Msg 5174 Each file size must be greater than or equal to 512 KB Whenever I see this error I wonder why someone is trying to attempt a database which is extremely small. Anyway, it does not matter what I think I keep on seeing this error often in industries. Anyway the solution of the error is equally interesting – just created larger database. Dilbert Humor This was very first encounter with database humor and I started to love it. It does not matter how many time we read this cartoon it does not get old. Generate Script with Data from Database – Database Publishing Wizard Generating schema script with data is one of the most frequently performed tasks among SQL Server Data Professionals. There are many ways to do the same. In the above article I demonstrated that how we can use the Database Publishing Wizard to accomplish the same. It was new to me at that time but I have not seen much of the adoption of the same still in the industry. Here is one of my videos where I demonstrate how we can generate data with schema. 2008 Delete Backup History – Cleanup Backup History Deleting backup history is important too but should be done carefully. If this is not carried out at regular interval there is good chance that MSDB will be filled up with all the old history. Every organization is different. Some would like to keep the history for 30 days and some for a year but there should be some limit. One should regularly archive the database backup history. South Asia MVP Open Days 2008 This was my very first year Microsoft MVP. I had Indeed big blast at the event and the fun was incredible. After this event I have attended many different MVP events but the fun and learning this particular event presented was amazing and just like me many others are not able to forget the same. Here are other links related to the event: South Asia MVP Open Day 2008 – Goa South Asia MVP Open Day 2008 – Goa – Day 1 South Asia MVP Open Day 2008 – Goa – Day 2 South Asia MVP Open Day 2008 – Goa – Day 3 2009 Enable or Disable Constraint  This is very simple script but I personally keep on forgetting it so I had blogged it. Till today, I keep on referencing this again and again as sometime a very little thing is hard to remember. Policy Based Management – Create, Evaluate and Fix Policies This article will cover the most spectacular feature of SQL 2008 – Policy-based management and how the configuration of SQL Server with policy-based management architecture can make a powerful difference. Policy based management is loaded with several advantages. It can help you implement various policies for reliable configuration of the system. It also provides additional administrative assistance to DBAs and helps them effortlessly manage various tasks of SQL Server across the enterprise. SQLPASS 2009 – My Very First SQPASS Experience Just Brilliant! I never had an experience such a thing in my life. SQL SQL and SQL – all around SQL! I am listing my own reasons here in order of importance to me. Networking with SQL fellows and experts Putting face to the name or avatar Learning and improving my SQL skills Understanding the structure of the largest SQL Server Professional Association Attending my favorite training sessions Since last time I have never missed a single time this event. This event is my favorite event and something keeps me going. Here are additional post related SQLPASS 2009. SQL PASS Summit, Seattle 2009 – Day 1 SQL PASS Summit, Seattle 2009 – Day 2 SQL PASS Summit, Seattle 2009 – Day 3 SQL PASS Summit, Seattle 2009 – Day 4 2010 Get All the Information of Database using sys.databases Even though we believe that we know everything about our database, we do not know a lot of things about our database. This little script enables us to know so many details about databases which we may not be familiar with. Run this on your server today and see how much you know your database. Reducing CXPACKET Wait Stats for High Transactional Database While engaging in a performance tuning consultation for a client, a situation occurred where they were facing a lot of CXPACKET Waits Stats. The client asked me if I could help them reduce this huge number of wait stats. I usually receive this kind of request from other client as well, but the important thing to understand is whether this question has any merits or benefits, or not. I discusses the same in this article – a bit long but insightful for sure. Error related to Database in Use There are so many database management operations in SQL Server which requires exclusive access to the database and it is not always possible to get it. When any database is online in SQL Server it either applications or system thread often accesses them. This means database can’t have exclusive access and the operations which required this access throws an error. There is very easy method to overcome this minor issue – a single line script can give you exclusive access to the database. Difference between DATETIME and DATETIME2 Developers have found the root reason of the problem when dealing with Date Functions – when data time values are converted (implicit or explicit) between different data types, which would lose some precision, so the result cannot match each other as expected. In this blog post I go over very interesting details and difference between DATETIME and DATETIME2 History of SQL Server Database Encryption I recently met Michael Coles and Rodeney Landrum the author of one of the kind book Expert SQL Server 2008 Encryption at SQLPASS in Seattle. During the conversation we ended up how Microsoft is evolving encryption technology. The same discussion lead to talking about history of encryption tools in SQL Server. Michale pointed me to page 18 of his book of encryption. He explicitly gave me permission to re-produce relevant part of history from his book. 2011 Functions FIRST_VALUE and LAST_VALUE with OVER clause and ORDER BY Some time an interesting feature and smart audience make a total difference in places. From last two days, I have been writing on SQL Server 2012 feature FIRST_VALUE and LAST_VALUE. I created a puzzle which was very interesting and got many people attempt to resolve it. It was based on following two articles: Introduction to FIRST_VALUE and LAST_VALUE Introduction to FIRST_VALUE and LAST_VALUE with OVER clause I even provided the hint about how one can solve this problem. The best part was many people solved the problem without using hints! Try your luck!  A Real Story of Book Getting ‘Out of Stock’ to A 25% Discount Story Available This is a great problem and everybody would love to have it. We had it and we loved it. Our book got out of stock in 48 hours of releasing and stocks were empty. We faced many issues and learned many valuable lessons. Some we were able to avoid in the future and some we are still facing it as those problems have no solutions. However, since that day – our books never gone out of stock. This inspiring learning story for us and I am confident that you will love to read it as well. Introduction to LEAD and LAG – Analytic Functions Introduced in SQL Server 2012 SQL Server 2012 introduces new analytical function LEAD() and LAG(). This function accesses data from a subsequent row (for lead) and previous row (for lag) in the same result set without the use of a self-join . It will be very difficult to explain this in words so I will attempt small example to explain you this function. I had a fantastic time writing this blog post and I am very confident when you read it, you will like the same. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: Memory Lane, PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology

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  • SQL SERVER – Weekly Series – Memory Lane – #049

    - by Pinal Dave
    Here is the list of selected articles of SQLAuthority.com across all these years. Instead of just listing all the articles I have selected a few of my most favorite articles and have listed them here with additional notes below it. Let me know which one of the following is your favorite article from memory lane. 2007 Two Connections Related Global Variables Explained – @@CONNECTIONS and @@MAX_CONNECTIONS @@CONNECTIONS Returns the number of attempted connections, either successful or unsuccessful since SQL Server was last started. @@MAX_CONNECTIONS Returns the maximum number of simultaneous user connections allowed on an instance of SQL Server. The number returned is not necessarily the number currently configured. Query Editor – Microsoft SQL Server Management Studio This post may be very simple for most of the users of SQL Server 2005. Earlier this year, I have received one question many times – Where is Query Analyzer in SQL Server 2005? I wrote small post about it and pointed many users to that post – SQL SERVER – 2005 Query Analyzer – Microsoft SQL SERVER Management Studio. Recently I have been receiving similar question. OUTPUT Clause Example and Explanation with INSERT, UPDATE, DELETE SQL Server 2005 has a new OUTPUT clause, which is quite useful. OUTPUT clause has access to insert and deleted tables (virtual tables) just like triggers. OUTPUT clause can be used to return values to client clause. OUTPUT clause can be used with INSERT, UPDATE, or DELETE to identify the actual rows affected by these statements. OUTPUT clause can generate a table variable, a permanent table, or temporary table. Even though, @@Identity will still work with SQL Server 2005, however I find the OUTPUT clause very easy and powerful to use. Let us understand the OUTPUT clause using an example. Find Name of The SQL Server Instance Based on database server stored procedures has to run different logic. We came up with two different solutions. 1) When database schema is very much changed, we wrote completely new stored procedure and deprecated older version once it was not needed. 2) When logic depended on Server Name we used global variable @@SERVERNAME. It was very convenient while writing migrating script which depended on the server name for the same database. Explanation of TRY…CATCH and ERROR Handling With RAISEERROR Function One of the developers at my company thought that we can not use the RAISEERROR function in new feature of SQL Server 2005 TRY… CATCH. When asked for an explanation he suggested SQL SERVER – 2005 Explanation of TRY… CATCH and ERROR Handling article as excuse suggesting that I did not give example of RAISEERROR with TRY…CATCH. We all thought it was funny. Just to keep records straight, TRY… CATCH can sure use RAISEERROR function. Different Types of Cache Objects Serveral kinds of objects can be stored in the procedure cache: Compiled Plans: When the query optimizer finishes compiling a query plan, the principal output is compiled plan. Execution contexts: While executing a compiled plan, SQL Server has to keep track of information about the state of execution. Cursors: Cursors track the execution state of server-side cursors, including the cursor’s current location within a resultset. Algebrizer trees: The Algebrizer’s job is to produce an algebrizer tree, which represents the logic structure of a query. Open SSMS From Command Prompt – sqlwb.exe Example This article is written by request and suggestion of Sr. Web Developer at my organization. Due to the nature of this article most of the content is referred from Book On-Line. sqlwbcommand prompt utility which opens SQL Server Management Studio. Squib command does not run queries from the command prompt. sqlcmd utility runs queries from command prompt, read for more information. 2008 Puzzle – Solution – Computed Columns Datatype Explanation Just a day before I wrote article SQL SERVER – Puzzle – Computed Columns Datatype Explanation which was inspired by SQL Server MVP Jacob Sebastian. I suggest that before continuing this article read the original puzzle question SQL SERVER – Puzzle – Computed Columns Datatype Explanation.The question was if the computed column was of datatype TINYINT how to create a Computed Column of datatype INT? 2008 – Find If Index is Being Used in Database It is very often I get a query that how to find if any index is being used in the database or not. If any database has many indexes and not all indexes are used it can adversely affect performance. If the number of indices are higher it reduces the INSERT / UPDATE / DELETE operation but increase the SELECT operation. It is recommended to drop any unused indexes from table to improve the performance. 2009 Interesting Observation – Execution Plan and Results of Aggregate Concatenation Queries If you want to see what’s going on here, I think you need to shift your point of view from an implementation-centric view to an ANSI point of view. ANSI does not guarantee processing the order. Figure 2 is interesting, but it will be potentially misleading if you don’t understand the ANSI rule-set SQL Server operates under in most cases. Implementation thinking can certainly be useful at times when you really need that multi-million row query to finish before the backup fire off, but in this case, it’s counterproductive to understanding what is going on. SQL Server Management Studio and Client Statistics Client Statistics are very important. Many a times, people relate queries execution plan to query cost. This is not a good comparison. Both parameters are different, and they are not always related. It is possible that the query cost of any statement is less, but the amount of the data returned is considerably larger, which is causing any query to run slow. How do we know if any query is retrieving a large amount data or very little data? 2010 I encourage all of you to go through complete series and write your own on the subject. If you write an article and send it to me, I will publish it on this blog with due credit to you. If you write on your own blog, I will update this blog post pointing to your blog post. SQL SERVER – ORDER BY Does Not Work – Limitation of the View 1 SQL SERVER – Adding Column is Expensive by Joining Table Outside View – Limitation of the View 2 SQL SERVER – Index Created on View not Used Often – Limitation of the View 3 SQL SERVER – SELECT * and Adding Column Issue in View – Limitation of the View 4 SQL SERVER – COUNT(*) Not Allowed but COUNT_BIG(*) Allowed – Limitation of the View 5 SQL SERVER – UNION Not Allowed but OR Allowed in Index View – Limitation of the View 6 SQL SERVER – Cross Database Queries Not Allowed in Indexed View – Limitation of the View 7 SQL SERVER – Outer Join Not Allowed in Indexed Views – Limitation of the View 8 SQL SERVER – SELF JOIN Not Allowed in Indexed View – Limitation of the View 9 SQL SERVER – Keywords View Definition Must Not Contain for Indexed View – Limitation of the View 10 SQL SERVER – View Over the View Not Possible with Index View – Limitations of the View 11 SQL SERVER – Get Query Running in Session I was recently looking for syntax where I needed a query running in any particular session. I always remembered the syntax and ha d actually written it down before, but somehow it was not coming to mind quickly this time. I searched online and I ended up on my own article written last year SQL SERVER – Get Last Running Query Based on SPID. I felt that I am getting old because I forgot this really simple syntax. Find Total Number of Transaction on Interval In one of my recent Performance Tuning assignments I was asked how do someone know how many transactions are happening on a server during certain interval. I had a handy script for the same. Following script displays transactions happened on the server at the interval of one minute. You can change the WAITFOR DELAY to any other interval and it should work. 2011 Here are two DMV’s which are newly introduced in SQL Server 2012 and provides vital information about SQL Server. DMV – sys.dm_os_volume_stats – Information about operating system volume DMV – sys.dm_os_windows_info – Information about Operating System SQL Backup and FTP – A Quick and Handy Tool I have used this tool extensively since 2009 at numerous occasion and found it to be very impressive. What separates it from the crowd the most – it is it’s apparent simplicity and speed. When I install SQLBackupAndFTP and configure backups – all in 1 or 2 minutes, my clients are always impressed. Quick Note about JOIN – Common Questions and Simple Answers In this blog post we are going to talk about join and lots of things related to the JOIN. I recently started office hours to answer questions and issues of the community. I receive so many questions that are related to JOIN. I will share a few of the same over here. Most of them are basic, but note that the basics are of great importance. 2012 Importance of User Without Login Question: “In recent version of SQL Server we can create user without login. What is the use of it?” Great question indeed. Let me first attempt to answer this question but after reading my answer I need your help. I want you to help him as well with adding more value to it. Preserve Leading Zero While Coping to Excel from SSMS Earlier I wrote two articles about how to efficiently copy data from SSMS to Excel. Since I wrote that post there are plenty of interest generated on this subject. There are a few questions I keep on getting over this subject. One of the question is how to get the leading zero preserved while copying the data from SSMS to Excel. Well it is almost the same way as my earlier post SQL SERVER – Excel Losing Decimal Values When Value Pasted from SSMS ResultSet. The key here is in EXCEL and not in SQL Server. Solution – 2 T-SQL Puzzles – Display Star and Shortest Code to Display 1 Earlier on this blog we had asked two puzzles. The response from all of you is nothing but Amazing. I have received 350+ responses. Many are valid and many were indeed something I had not thought about it. I strongly suggest you read all the puzzles and their answers here - trust me if you start reading the comments you will not stop till you read every single comment. Seriously trust me on it. Personally I have learned a lot from it. Identify Most Resource Intensive Queries – SQL in Sixty Seconds #028 – Video http://www.youtube.com/watch?v=TvlYy-TGaaA Importance of User Without Login – T-SQL Demo Script Earlier I wrote a blog post about SQL SERVER – Importance of User Without Login and my friend and SQL Expert Vinod Kumar has written excellent follow up blog post about Contained Databases inside SQL Server 2012. Now lots of people asked me if I can also explain the same concept again so here is the small demonstration for it. Let me show you how login without user can help. Before we continue on this subject I strongly recommend that you read my earlier blog post here. In following demo I am going to demonstrate following situation. Login using the System Admin account Create a user without login Checking Access Impersonate the user without login Checking Access Revert Impersonation Give Permission to user without login Impersonate the user without login Checking Access Revert Impersonation Clean up Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: Memory Lane, PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology

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  • SQL SERVER – Weekly Series – Memory Lane – #039

    - by Pinal Dave
    Here is the list of selected articles of SQLAuthority.com across all these years. Instead of just listing all the articles I have selected a few of my most favorite articles and have listed them here with additional notes below it. Let me know which one of the following is your favorite article from memory lane. 2007 FQL – Facebook Query Language Facebook list following advantages of FQL: Condensed XML reduces bandwidth and parsing costs. More complex requests can reduce the number of requests necessary. Provides a single consistent, unified interface for all of your data. It’s fun! UDF – Get the Day of the Week Function The day of the week can be retrieved in SQL Server by using the DatePart function. The value returned by the function is between 1 (Sunday) and 7 (Saturday). To convert this to a string representing the day of the week, use a CASE statement. UDF – Function to Get Previous And Next Work Day – Exclude Saturday and Sunday While reading ColdFusion blog of Ben Nadel Getting the Previous Day In ColdFusion, Excluding Saturday And Sunday, I realize that I use similar function on my SQL Server Database. This function excludes the Weekends (Saturday and Sunday), and it gets previous as well as next work day. Complete Series of SQL Server Interview Questions and Answers Data Warehousing Interview Questions and Answers – Introduction Data Warehousing Interview Questions and Answers – Part 1 Data Warehousing Interview Questions and Answers – Part 2 Data Warehousing Interview Questions and Answers – Part 3 Data Warehousing Interview Questions and Answers Complete List Download 2008 Introduction to Log Viewer In SQL Server all the windows event logs can be seen along with SQL Server logs. Interface for all the logs is same and can be launched from the same place. This log can be exported and filtered as well. DBCC SHRINKFILE Takes Long Time to Run If you are DBA who are involved with Database Maintenance and file group maintenance, you must have experience that many times DBCC SHRINKFILE operations takes a long time but any other operations with Database are relatively quicker. mssqlsystemresource – Resource Database The purpose of resource database is to facilitates upgrading to the new version of SQL Server without any hassle. In previous versions whenever version of SQL Server was upgraded all the previous version system objects needs to be dropped and new version system objects to be created. 2009 Puzzle – Write Script to Generate Primary Key and Foreign Key In SQL Server Management Studio (SSMS), there is no option to script all the keys. If one is required to script keys they will have to manually script each key one at a time. If database has many tables, generating one key at a time can be a very intricate task. I want to throw a question to all of you if any of you have scripts for the same purpose. Maximizing View of SQL Server Management Studio – Full Screen – New Screen I had explained the following two different methods: 1) Open Results in Separate Tab - This is a very interesting method as result pan shows up in a different tab instead of the splitting screen horizontally. 2) Open SSMS in Full Screen - This works always and to its best. Not many people are aware of this method; hence, very few people use it to enhance performance. 2010 Find Queries using Parallelism from Cached Plan T-SQL script gets all the queries and their execution plan where parallelism operations are kicked up. Pay attention there is TOP 10 is used, if you have lots of transactional operations, I suggest that you change TOP 10 to TOP 50 This is the list of the all the articles in the series of computed columns. SQL SERVER – Computed Column – PERSISTED and Storage This article talks about how computed columns are created and why they take more storage space than before. SQL SERVER – Computed Column – PERSISTED and Performance This article talks about how PERSISTED columns give better performance than non-persisted columns. SQL SERVER – Computed Column – PERSISTED and Performance – Part 2 This article talks about how non-persisted columns give better performance than PERSISTED columns. SQL SERVER – Computed Column and Performance – Part 3 This article talks about how Index improves the performance of Computed Columns. SQL SERVER – Computed Column – PERSISTED and Storage – Part 2 This article talks about how creating index on computed column does not grow the row length of table. SQL SERVER – Computed Columns – Index and Performance This article summarized all the articles related to computed columns. 2011 SQL SERVER – Interview Questions and Answers – Frequently Asked Questions – Data Warehousing Concepts – Day 21 of 31 What is Data Warehousing? What is Business Intelligence (BI)? What is a Dimension Table? What is Dimensional Modeling? What is a Fact Table? What are the Fundamental Stages of Data Warehousing? What are the Different Methods of Loading Dimension tables? Describes the Foreign Key Columns in Fact Table and Dimension Table? What is Data Mining? What is the Difference between a View and a Materialized View? SQL SERVER – Interview Questions and Answers – Frequently Asked Questions – Data Warehousing Concepts – Day 22 of 31 What is OLTP? What is OLAP? What is the Difference between OLTP and OLAP? What is ODS? What is ER Diagram? SQL SERVER – Interview Questions and Answers – Frequently Asked Questions – Data Warehousing Concepts – Day 23 of 31 What is ETL? What is VLDB? Is OLTP Database is Design Optimal for Data Warehouse? If denormalizing improves Data Warehouse Processes, then why is the Fact Table is in the Normal Form? What are Lookup Tables? What are Aggregate Tables? What is Real-Time Data-Warehousing? What are Conformed Dimensions? What is a Conformed Fact? How do you Load the Time Dimension? What is a Level of Granularity of a Fact Table? What are Non-Additive Facts? What is a Factless Facts Table? What are Slowly Changing Dimensions (SCD)? SQL SERVER – Interview Questions and Answers – Frequently Asked Questions – Data Warehousing Concepts – Day 24 of 31 What is Hybrid Slowly Changing Dimension? What is BUS Schema? What is a Star Schema? What Snow Flake Schema? Differences between the Star and Snowflake Schema? What is Difference between ER Modeling and Dimensional Modeling? What is Degenerate Dimension Table? Why is Data Modeling Important? What is a Surrogate Key? What is Junk Dimension? What is a Data Mart? What is the Difference between OLAP and Data Warehouse? What is a Cube and Linked Cube with Reference to Data Warehouse? What is Snapshot with Reference to Data Warehouse? What is Active Data Warehousing? What is the Difference between Data Warehousing and Business Intelligence? What is MDS? Explain the Paradigm of Bill Inmon and Ralph Kimball. SQL SERVER – Azure Interview Questions and Answers – Guest Post by Paras Doshi – Day 25 of 31 Paras Doshi has submitted 21 interesting question and answers for SQL Azure. 1.What is SQL Azure? 2.What is cloud computing? 3.How is SQL Azure different than SQL server? 4.How many replicas are maintained for each SQL Azure database? 5.How can we migrate from SQL server to SQL Azure? 6.Which tools are available to manage SQL Azure databases and servers? 7.Tell me something about security and SQL Azure. 8.What is SQL Azure Firewall? 9.What is the difference between web edition and business edition? 10.How do we synchronize On Premise SQL server with SQL Azure? 11.How do we Backup SQL Azure Data? 12.What is the current pricing model of SQL Azure? 13.What is the current limitation of the size of SQL Azure DB? 14.How do you handle datasets larger than 50 GB? 15.What happens when the SQL Azure database reaches Max Size? 16.How many databases can we create in a single server? 17.How many servers can we create in a single subscription? 18.How do you improve the performance of a SQL Azure Database? 19.What is code near application topology? 20.What were the latest updates to SQL Azure service? 21.When does a workload on SQL Azure get throttled? SQL SERVER – Interview Questions and Answers – Guest Post by Malathi Mahadevan – Day 26 of 31 Malachi had asked a simple question which has several answers. Each answer makes you think and ponder about the reality of the IT world. Look at the simple question – ‘What is the toughest challenge you have faced in your present job and how did you handle it’? and its various answers. Each answer has its own story. SQL SERVER – Interview Questions and Answers – Guest Post by Rick Morelan – Day 27 of 31 Rick Morelan of Joes2Pros has written an excellent blog post on the subject how to find top N values. Most people are fully aware of how the TOP keyword works with a SELECT statement. After years preparing so many students to pass the SQL Certification I noticed they were pretty well prepared for job interviews too. Yes, they would do well in the interview but not great. There seemed to be a few questions that would come up repeatedly for almost everyone. Rick addresses similar questions in his lucid writing skills. 2012 Observation of Top with Index and Order of Resultset SQL Server has lots of things to learn and share. It is amazing to see how people evaluate and understand different techniques and styles differently when implementing. The real reason may be absolutely different but we may blame something totally different for the incorrect results. Read the blog post to learn more. How do I Record Video and Webcast How to Convert Hex to Decimal or INT Earlier I asked regarding a question about how to convert Hex to Decimal. I promised that I will post an answer with Due Credit to the author but never got around to post a blog post around it. Read the original post over here SQL SERVER – Question – How to Convert Hex to Decimal. Query to Get Unique Distinct Data Based on Condition – Eliminate Duplicate Data from Resultset The natural reaction will be to suggest DISTINCT or GROUP BY. However, not all the questions can be solved by DISTINCT or GROUP BY. Let us see the following example, where a user wanted only latest records to be displayed. Let us see the example to understand further. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: Memory Lane, PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology

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  • SQL SERVER – Weekly Series – Memory Lane – #007

    - by pinaldave
    Here is the list of selected articles of SQLAuthority.com across all these years. Instead of just listing all the articles I have selected a few of my most favorite articles and have listed them here with additional notes below it. Let me know which one of the following is your favorite article from memory lane. 2006 Find Stored Procedure Related to Table in Database – Search in All Stored Procedure In 2006 I wrote a small script which will help user  find all the Stored Procedures (SP) which are related to one or more specific tables. This was quite a popular script however, in SQL Server 2012 the same can be achieved using new DMV sys.sql-expression_dependencies. I recently blogged about it over Find Referenced or Referencing Object in SQL Server using sys.sql_expression_dependencies. 2007 SQL SERVER – Versions, CodeNames, Year of Release 1993 – SQL Server 4.21 for Windows NT 1995 – SQL Server 6.0, codenamed SQL95 1996 – SQL Server 6.5, codenamed Hydra 1999 – SQL Server 7.0, codenamed Sphinx 1999 – SQL Server 7.0 OLAP, codenamed Plato 2000 – SQL Server 2000 32-bit, codenamed Shiloh (version 8.0) 2003 – SQL Server 2000 64-bit, codenamed Liberty 2005 – SQL Server 2005, codenamed Yukon (version 9.0) 2008 – SQL Server 2008, codenamed Katmai (version 10.0) 2011 – SQL Server 2008, codenamed Denali (version 11.0) Search String in Stored Procedure Searching sting in the stored procedure is one of the most frequent task developer do. They might be searching for a table, view or any other details. I have written a script to do the same in SQL Server 2000 and SQL Server 2005. This is worth bookmarking blog post. There is an alternative way to do the same as well here is the example. 2008 SQL SERVER – Refresh Database Using T-SQL NO! Some of the questions have a single answer NO! You may want to read the question in the original blog post. I had a great time saying No! SQL SERVER – Delete Backup History – Cleanup Backup History SQL Server stores history of all the taken backup forever. History of all the backup is stored in the msdb database. Many times older history is no more required. Following Stored Procedure can be executed with a parameter which takes days of history to keep. In the following example 30 is passed to keep a history of month. 2009 Stored Procedure are Compiled on First Run – SP taking Longer to Run First Time Is stored procedure pre-compiled? Why the Stored Procedure takes a long time to run for the first time?  This is a very common questions often discussed by developers and DBAs. There is an absolutely definite answer but the question has been discussed forever. There is a misconception that stored procedures are pre-compiled. They are not pre-compiled, but compiled only during the first run. For every subsequent runs, it is for sure pre-compiled. Read the entire article for example and demonstration. Removing Key Lookup – Seek Predicate – Predicate – An Interesting Observation Related to Datatypes This is one of the most important performance tuning lesson on my blog. I suggest this weekend you spend time reading them and let me know what you think about the concepts which I have demonstrated in the four part series. Part 1 | Part 2 | Part 3 | Part 4 Seek Predicate is the operation that describes the b-tree portion of the Seek. Predicate is the operation that describes the additional filter using non-key columns. Based on the description, it is very clear that Seek Predicate is better than Predicate as it searches indexes whereas in Predicate, the search is on non-key columns – which implies that the search is on the data in page files itself. Policy Based Management – Create, Evaluate and Fix Policies This article will cover the most spectacular feature of SQL Server – Policy-based management and how the configuration of SQL Server with policy-based management architecture can make a powerful difference. Policy based management is loaded with several advantages. It can help you implement various policies for reliable configuration of the system. It also provides additional administration assistance to DBAs and helps them effortlessly manage various tasks of SQL Server across the enterprise. 2010 Recycle Error Log – Create New Log file without Server Restart Once I observed a DBA to restaring the SQL Server when he needed new error log file. This was funny and sad both at the same time. There is no need to restart the server to create a new log file or recycle the log file. You can run sp_cycle_errorlog and achieve the same result. Get Database Backup History for a Single Database Simple but effective script! Reducing CXPACKET Wait Stats for High Transactional Database The subject is very complex and I have done my best to simplify the concept. In simpler words, when a parallel operation is created for SQL Query, there are multiple threads for a single query. Each query deals with a different set of the data (or rows). Due to some reasons, one or more of the threads lag behind, creating the CXPACKET Wait Stat. Threads which came first have to wait for the slower thread to finish. The Wait by a specific completed thread is called CXPACKET Wait Stat. Information Related to DATETIME and DATETIME2 There are quite a lot of confusion with DATETIME and DATETIME2. DATETIME2 is also one of the underutilized datatype of SQL Server.  In this blog post I have written a follow up of the my earlier datetime series where I clarify a few of the concepts related to datetime. Difference Between GETDATE and SYSDATETIME Difference Between DATETIME and DATETIME2 – WITH GETDATE Difference Between DATETIME and DATETIME2 2011 Introduction to CUME_DIST – Analytic Functions Introduced in SQL Server 2012 SQL Server 2012 introduces new analytical function CUME_DIST(). This function provides cumulative distribution value. It will be very difficult to explain this in words so I will attempt small example to explain you this function. Instead of creating new table, I will be using AdventureWorks sample database as most of the developer uses that for experiment. Introduction to FIRST _VALUE and LAST_VALUE – Analytic Functions Introduced in SQL Server 2012 SQL Server 2012 introduces new analytical functions FIRST_VALUE() and LAST_VALUE(). This function returns first and last value from the list. It will be very difficult to explain this in words so I’d like to attempt to explain its function through a brief example. Instead of creating a new table, I will be using the AdventureWorks sample database as most developers use that for experiment purposes. OVER clause with FIRST _VALUE and LAST_VALUE – Analytic Functions Introduced in SQL Server 2012 – ROWS BETWEEN UNBOUNDED PRECEDING AND UNBOUNDED FOLLOWING “Don’t you think there is bug in your first example where FIRST_VALUE is remain same but the LAST_VALUE is changing every line. I think the LAST_VALUE should be the highest value in the windows or set of result.” Puzzle – Functions FIRST_VALUE and LAST_VALUE with OVER clause and ORDER BY You can see that row number 2, 3, 4, and 5 has same SalesOrderID = 43667. The FIRST_VALUE is 78 and LAST_VALUE is 77. Now if these function was working on maximum and minimum value they should have given answer as 77 and 80 respectively instead of 78 and 77. Also the value of FIRST_VALUE is greater than LAST_VALUE 77. Why? Explain in detail. Introduction to LEAD and LAG – Analytic Functions Introduced in SQL Server 2012 SQL Server 2012 introduces new analytical function LEAD() and LAG(). This functions accesses data from a subsequent row (for lead) and previous row (for lag) in the same result set without the use of a self-join . It will be very difficult to explain this in words so I will attempt small example to explain you this function. Instead of creating new table, I will be using AdventureWorks sample database as most of the developer uses that for experiment. A Real Story of Book Getting ‘Out of Stock’ to A 25% Discount Story Available Our book was out of stock in 48 hours of it was arrived in stock! We got call from the online store with a request for more copies within 12 hours. But we had printed only as many as we had sent them. There were no extra copies. We finally talked to the printer to get more copies. However, due to festivals and holidays the copies could not be shipped to the online retailer for two days. We knew for sure that they were going to be out of the book for 48 hours. This is the story of how we overcame that situation! Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: Memory Lane, PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology

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