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  • Efficient way of detecting a touched object in a game?

    - by Pin
    Imagine a Sims-like 2D game for a touch based mobile phone where one can interact with virtually any object in the scene. How can I efficiently detect which object is being touched by the player? In my short experience, looping through all the visible objects in the scene and checking if they're touched has so far done the job, but when there may be many many moving objects in the screen that sounds kind of inefficient isn't it? Keeping the visible moving objects list can consume time in itself as one may have to loop through all of them each frame. Other solutions I've thought are: Spatial hashing. Divide the screen as a grid and place the visible objects in the corresponding bucket. Detection of the clicked object is fast but there's additional overhead for placing the objects in the correct bucket each frame. Maintaining a quad-tree. Moving objects have to be rearranged all the time, the previous solution looks better. What is usually done in this case?

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  • Good Compression for Slow-mo Video

    - by marienbad
    What's the best way to deliver super slow-motion video to the browser? This seems to me to be a special case, because with super slow-mo video (such as 10,000 frames per second) the visual difference from frame to frame is minimal. As such, it's easy to compress highly. Please suggest codecs, as well as encoding software, backend software, software configuration tips, and services like youtube. My goal is to get about 100 frames of QVGA video to the browser in 500KB. By the way, remember that Radiohead In Rainbows site?

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  • Programming for Digital frames

    - by spartan2417
    A project has recently come to my attention but i have no idea where to start or even if its possible. The idea revolves around programming a clock that is displayed inside a digital photo frame. The user would then be able to put different pictures corresponding to different times inside a usb pen for example, which would load as soon as you put the usb in. The project itself would be a really neat project - if it was just on a computer. I have no idea if what im talking about it even possible on a digital photo frame and if it is what language? Anyone who has any input at all would be great. My current idea is to maybe have a small device at the back, SSD, that runs the program through a screen, completely by passing standard digital photo frames, again though i dont know how to begin with this. And yes ive tried google (although it helps to know what to google).

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  • Termite colony simulator using java

    - by ashii
    hi everyone, i hve to design a simulator that will maintain an environment, which consists of a collection of patches arranged in a rectangular grid of arbitrary size. Each patch contains zero or more wood chips. A patch may be occupied by one or more termites or predators, which are mobile entities that live within the world and behave according to simple rules. A TERMITE can pick up a wood chip from the patch that it is currently on, or drop a wood chip that it is carrying. Termites travel around the grid by moving randomly from their current patch to a neighbouring patch, in one of four possible directions. New termites may hatch from eggs, and this is simulated by the appearance of a new termite at a random patch within the environment. A PREDATOR moves in a similar way to termites, and if a predator moves onto a patch that is occupied by a termite, then the predator eats the termite. At initialization, the termites, predators, and wood chips are distributed randomly in the environment. Simulation then proceeds in a loop, and the new state of the environment is obtained at each iteration. i have designed the arena using jpanel but im not able to randomnly place wood,termite and predator in that arena. can any one help me out?? my code for the arena is as following: 01 import java.awt.*; 02 import javax.swing.*; 03 04 public class Arena extends JPanel 05 { 06 private static final int Rows = 8; 07 private static final int Cols = 8; 08 public void paint(Graphics g) 09 { 10 Dimension d = this.getSize(); 11 // don't draw both sets of squares, when you can draw one 12 // fill in the entire thing with one color 13 g.setColor(Color.WHITE); 14 // make the background 15 g.fillRect(0,0,d.width,d.height); 16 // draw only black 17 g.setColor(Color.BLACK); 18 // pick a square size based on the smallest dimension 19 int sqsize = ((d.width<d.height) ? d.width/Cols : d.height/Rows); 20 // loop for rows 21 for (int row=0; row<Rows; row++) 22 { 23 int y = row*sqsize; // y stays same for entire row, set here 24 int x = (row%2)*sqsize; // x starts at 0 or one square in 25 for (int i=0; i<Cols/2; i++) 26 { 27 // you will only be drawing half the squares per row 28 // draw square 29 g.fillRect(x,y,sqsize,sqsize); 30 // move two square sizes over 31 x += sqsize*2; 32 } 33 } 34 35 } 36 37 38 39 public void update(Graphics g) { paint(g); } 40 41 42 43 public static void main (String[] args) 44 { 45 46 JFrame frame = new JFrame("Arena"); 47 frame.setSize(600,400); 48 frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); 49 frame.setContentPane(new Arena()); 50 frame.setVisible(true); 51 } 52 53 }

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  • Data for animation

    - by saadtaame
    Say you are using C/SDL for a 2D game project. It's often the case that people use a structure to represent a frame in an animation. The struct consists of an image and how much time the frame is supposed to be visible. Is this data sufficient to represent somewhat complex animatio? Is it a good idea to separate animation management code and animation data? Can somebody provide a link to animations tutorials that store animations in a file and retrieve them when needed. I read this in a book (AI game programming wisdom) but would like to see a real implementation.

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  • How can I support scrolling when using batched rendering for my tiles?

    - by dardanel
    I have tiled map 100*75 and tiles are 32*32 pixel.I want to use batching for performance .I don't figure it out , because of my game needs scrolling and every frame i draw 22*16 tiles (my screen is 20*16 tile) .I thought that batching tiles for every frame .Is it good or any suggestion? edit :to more clarify I want to use occlusion culling and batching at the same time.I thought that drawing only visible areas and batching them together .But there is a something i couldn't figure out .When scrolling screen with translate matrix , if one row become invisible , I bind new row and batch them again.Every batched objects needs to buffer again.So I batch tiles and buffer to VBO every time when one row become invisible .I don't know these way is efficient or not .This is my question .And i am open to any suggestions.

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  • Can't access some websites using Ubuntu 13.10

    - by Adame Doe
    Something's wrong with Ubuntu. Since I've upgraded to 13.10, I can't access some websites for no apparent reason. I've tried everything imaginable to solve this problem : Made sure that MTUs are the same, Disabled IPv6 in both the network manager and used browsers, Deactivated my network keys, DMZed my computer, Used other DNS like Google and OpenDNS, Checked that no firewall was running my computer ... And it's the same result. I even tried to reinstall Ubuntu a couple of times, but no luck. The most annoying thing about it is I can't access wordpress.org! So, there's no way it could be an ISP restriction of some kind. When I use a VPN, I can access pretty much anything. I'm really frustrated because I have to use wordpress.org very often. Any clue? ifconfig adame@adame-ws:~$ ifconfig eth0 Link encap:Ethernet HWaddr 00:26:18:3d:b0:7c inet addr:10.42.0.1 Bcast:10.42.0.255 Mask:255.255.255.0 inet6 addr: fe80::226:18ff:fe3d:b07c/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:8024 errors:0 dropped:0 overruns:0 frame:0 TX packets:7966 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:684480 (684.4 KB) TX bytes:616608 (616.6 KB) lo Link encap:Local Loopback inet addr:127.0.0.1 Mask:255.0.0.0 inet6 addr: ::1/128 Scope:Host UP LOOPBACK RUNNING MTU:65536 Metric:1 RX packets:8222 errors:0 dropped:0 overruns:0 frame:0 TX packets:8222 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:0 RX bytes:568269 (568.2 KB) TX bytes:568269 (568.2 KB) wlan0 Link encap:Ethernet HWaddr 00:19:70:40:85:eb inet addr:192.168.2.3 Bcast:192.168.2.255 Mask:255.255.255.0 inet6 addr: fe80::219:70ff:fe40:85eb/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1464 Metric:1 RX packets:123705 errors:0 dropped:0 overruns:0 frame:0 TX packets:98141 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:94963545 (94.9 MB) TX bytes:10387470 (10.3 MB) /etc/hosts 127.0.0.1 localhost 127.0.1.1 adame-ws ::1 ip6-localhost ip6-loopback fe00::0 ip6-localnet ff00::0 ip6-mcastprefix ff02::1 ip6-allnodes ff02::2 ip6-allrouters tracepath wordpress.org 1: adame-ws.local 0.092ms pmtu 1500 1: 192.168.2.1 1.300ms asymm 2 1: 192.168.2.1 1.060ms asymm 2 2: no reply 3: no reply 4: no reply 5: no reply 6: no reply 7: no reply 8: no reply ... keep on going like that ping wordpress.org adame@adame-ws:~$ ping wordpress.org PING wordpress.org (66.155.40.250) 56(84) bytes of data. --- wordpress.org ping statistics --- 10 packets transmitted, 0 received, 100% packet loss, time 9071ms

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  • All images are gone after open a doc file created by libreoffice writer

    - by user71465
    I got a paper template in .doc format from a conference site. Now when i work on it with libreoffice and insert image to it and insert caption for the image, after closing the file and opening it again, all images are gone. I saw that when the image Anchor is set "to frame" the image will be gone but when it is set to e.g. "to paragraph" it will maintain but it's alignment will be corrupted. Also, i need the Anchor to be set to "Frame". What can I do? I searched the net but i didn't find a good answer.

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  • OpenGL ES 2.0. Sprite Sheet Animation

    - by Project Dumbo Dev
    I've found a bunch of tutorials on how to make this work on Open GL 1 & 1.1 but I can't find it for 2.0. I would work it out by loading the texture and use a matrix on the vertex shader to move through the sprite sheet. I'm looking for the most efficient way to do it. I've read that when you do the thing I'm proposing you are constantly changing the VBO's and that that is not good. Edit: Been doing some research myself. Came upon this two Updating Texture and referring to the one before PBO's. I can't use PBO's since i'm using ES version of OpenGL so I suppose the best way is to make FBO's but, what I still don't get, is if I should create a Sprite atlas/batch and make a FBO/loadtexture for each frame of if I should load every frame into the buffer and change just de texture directions.

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  • Ubuntu 12.04 Ethernet works sporadically on lenovo x200 tablet

    - by user73100
    This is what I got from ifconfig eth0 Link encap:Ethernet HWaddr 00:1f:16:1a:0e:7e inet6 addr: fe80::21f:16ff:fe1a:e7e/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:34 errors:0 dropped:0 overruns:0 frame:0 TX packets:387 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:16036 (16.0 KB) TX bytes:98315 (98.3 KB) Interrupt:20 Memory:f2700000-f2720000 lo Link encap:Local Loopback inet addr:127.0.0.1 Mask:255.0.0.0 inet6 addr: ::1/128 Scope:Host UP LOOPBACK RUNNING MTU:16436 Metric:1 RX packets:704 errors:0 dropped:0 overruns:0 frame:0 TX packets:704 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:0 RX bytes:55280 (55.2 KB) TX bytes:55280 (55.2 KB)

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  • Data-driven animations

    - by saadtaame
    Say you are using C/SDL for a 2D game project. It's often the case that people use a structure to represent a frame in an animation. The struct consists of an image and how much time the frame is supposed to be visible. Is this data sufficient to represent somewhat complex animation? Is it a good idea to separate animation management code and animation data? Can somebody provide a link to animations tutorials that store animations in a file and retrieve them when needed. I read this in a book (AI game programming wisdom) but would like to see a real implementation.

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  • How to display consistent background image

    - by Tofu_Craving_Redish_BlueDragon
    Drawing a large background is relatively slow in PyGame. In order to avoid drawing BG every frame, you could draw it once, then do nothing. However, if something is overdrawn onto the surface and keeps moving, you will need to redraw the background in order to "erase" the color pixels left by moving object; otherwise, you will have "traces" of the moving object. I have a moving object in my PyGame. However, I do not want to "clear the color buffer" by redrawing the background image. Redrawing the background image every frame is slow. My solution : I will "clear" only required portions (where the "traces" of moving object are left) of the "buffer" by redrawing portions of background. Is there any other better way to have a consistent background?

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  • How do I swap two objects in a GC language without triggering GC?

    - by TenFour04
    I have two array lists. that I want to swap each frame. My question is, does the variable 'temp' need to be a member variable to avoid triggering GC, assuming this method is called on dozens of objects each frame? I'm not creating a new object, just a new reference to an object. public void LateUpdate(){ ArrayList<int> temp = previousFrameCollisions; previousFrameCollisions = currentFrameCollisions; currentFrameCollisions = temp; currentFrameCollisions.clear(); } I've been told there's no reason to make a primitive into a member variable just to avoid GC, so my best guess is that this also applies to object references.

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  • Particle system lifetimes in OpenGL ES 2

    - by user16547
    I don't know how to work with my particle's lifetimes. My design is simple: each particle has a position, a speed and a lifetime. At each frame, each particle should update its position like this: position.y = position.y + INCREMENT * speed.y However, I'm having difficulties in choosing my INCREMENT. If I set it to some sort of FRAME_COUNT, it looks fine until FRAME_COUNT has to be set back to 0. The effect will be that all particles start over at the same time, which I don't want to happen. I want my particles sort of live "independent" of each other. That's the reason I need a lifetime, but I don't know how to make use of it. I added a lifetime for each particle in the particle buffer, but I also need an individual increment that's updated on each frame, so that when PARTICLE_INCREMENT = PARTICLE_LIFETIME, each increment goes back to 0. How can I achieve something like that?

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  • How do I swap two objects in C# (specifically Mono) without triggering GC?

    - by TenFour04
    I have two array lists. that I want to swap each frame. My question is, does the variable 'temp' need to be a member variable to avoid triggering GC, assuming this method is called on dozens of objects each frame? I'm not creating a new object, just a new reference to an object. public void LateUpdate(){ ArrayList<int> temp = previousFrameCollisions; previousFrameCollisions = currentFrameCollisions; currentFrameCollisions = temp; currentFrameCollisions.clear(); } I've been told there's no reason to make a primitive into a member variable just to avoid GC, so my best guess is that this also applies to object references.

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  • When should I clear an auxilliary render target?

    - by Raptormeat
    I'm using a few different render targets in my game in addition to the back buffer. These other render targets are only used in a few places, for specific tasks. I'm wondering when I should be clearing them. Right now I clear all of my render targets at the beginning of the frame, and it seems like I'm waiting for all the textures to clear before the rest of the drawing gets underway. Would it be more efficient to clear these textures later in the frame, when they aren't being used? Is there any hope of the GPU sort of clearing them "on the side" while unrelated rendering is happening? Or are these tasks always sequential and will I always need to wait for clearing?

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  • Sound Delay With AVAudio Player

    - by Will Youmans
    I'm using the following code in my viewDidLoad to load a sound: NSURL * url = [NSURL fileURLWithPath: [NSString stringWithFormat:@"%@/Moto - Hit Sound.mp3", [[NSBundle mainBundle] resourcePath]]]; NSError * error; hitSoundPlayer = [[AVAudioPlayer alloc]initWithContentsOfURL:url error:&error]; hitSoundPlayer.numberOfLoops = 0; Then I'm using this in a void method to play the sound: if(CGRectIntersectsRect(main.frame, enemy1.frame)){ [hitSoundPlayer play]; } This does seem to work, however the first time the sound is played there is a lot of lag and the game stops temporarily. I'm using this same method for when in an IBAction and it works fine, it must be the fact that it's also detecting a collision that makes the sound lag. If I want to be able to play sounds quickly and on the spot without any sort of lag am I doing the right thing? Do I want to use another method? I'm not using any frameworks like cocos2d. If you need to see any more code just ask.

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  • Should the networking of my game be a component or a service?

    - by aalcutt
    I am working on a windows game and I am trying to understand the XNA GameComponents and GameServices classes and use. From what I understand about a component is that it has an Update method that gets call in every frame, and a service can be referenced from other components if needed. So the way I think a network component would work is that in its Update method it would receive and send data. It probably makes sense to receive the network data once per frame, but it doesn't for sending it. Shouldn't the game send its own updates to others the moment it has it to cut down on lag?

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  • repaint problem

    - by user357816
    I have a problem with my repaint in the method move. I dont know what to doo, the code is below import java.awt.*; import java.io.*; import java.text.*; import java.util.*; import javax.sound.sampled.*; import javax.swing.*; import javax.swing.Timer; import java.awt.event.*; import java.lang.*; public class bbb extends JPanel { public Stack<Integer> stacks[]; public JButton auto,jugar,nojugar; public JButton ok,ok2; public JLabel info=new JLabel("Numero de Discos: "); public JLabel instruc=new JLabel("Presiona la base de las torres para mover las fichas"); public JLabel instruc2=new JLabel("No puedes poner una pieza grande sobre una pequenia!"); public JComboBox numeros=new JComboBox(); public JComboBox velocidad=new JComboBox(); public boolean seguir=false,parar=false,primera=true; public int n1,n2,n3; public int click1=0; public int opcion=1,tiempo=50; public int op=1,continuar=0,cont=0; public int piezas=0; public int posx,posy; public int no; public bbb() throws IOException { stacks = new Stack[3]; stacks[0]=new Stack<Integer>(); stacks[1]=new Stack<Integer>(); stacks[2]=new Stack<Integer>(); setPreferredSize(new Dimension(1366,768)); ok=new JButton("OK"); ok.setBounds(new Rectangle(270,50,70,25)); ok.addActionListener(new okiz()); ok2=new JButton("OK"); ok2.setBounds(new Rectangle(270,50,70,25)); ok2.addActionListener(new vel()); add(ok2);ok2.setVisible(false); auto=new JButton("Automatico"); auto.setBounds(new Rectangle(50,80,100,25)); auto.addActionListener(new a()); jugar=new JButton("PLAY"); jugar.setBounds(new Rectangle(100,100,70,25)); jugar.addActionListener(new play()); nojugar=new JButton("PAUSE"); nojugar.setBounds(new Rectangle(100,150,70,25)); nojugar.addActionListener(new stop()); setLayout(null); info.setBounds(new Rectangle(50,50,170,25)); info.setForeground(Color.white); instruc.setBounds(new Rectangle(970,50,570,25)); instruc.setForeground(Color.white); instruc2.setBounds(new Rectangle(970,70,570,25)); instruc2.setForeground(Color.white); add(instruc);add(instruc2); add(jugar);add(nojugar);jugar.setVisible(false);nojugar.setVisible(false); add(info); info.setVisible(false); add(ok); ok.setVisible(false); add(auto); numeros.setBounds(new Rectangle(210,50,50,25)); numeros.addItem(1);numeros.addItem(2);numeros.addItem(3);numeros.addItem(4);numeros.addItem(5); numeros.addItem(6);numeros.addItem(7);numeros.addItem(8);numeros.addItem(9);numeros.addItem(10); add(numeros); numeros.setVisible(false); velocidad.setBounds(new Rectangle(150,50,100,25)); velocidad.addItem("Lenta"); velocidad.addItem("Intermedia"); velocidad.addItem("Rapida"); add(velocidad); velocidad.setVisible(false); } public void Mover(int origen, int destino) { for (int i=0;i<3;i++) { System.out.print("stack "+i+": "); for(int n : stacks[i]) System.out.print(n+";"); System.out.println(""); } System.out.println("de <"+origen+"> a <"+destino+">"); stacks[destino].push(stacks[origen].pop()); System.out.println(""); this.validate(); this.repaint( ); } public void hanoi(int origen, int destino, int cuantas) { while (parar) {} if (cuantas <= 1) Mover(origen,destino); else { hanoi(origen,3 - (origen+destino),cuantas-1); Mover(origen,destino); hanoi(3 - (origen+destino),destino,cuantas-1); } } public void paintComponent(Graphics g) { ImageIcon fondo= new ImageIcon("fondo.jpg"); g.drawImage(fondo.getImage(),0, 0,1366,768,null); g.setColor(new Color((int)(Math.random() * 254), (int)(Math.random() *255), (int)(Math.random() * 255))); g.fillRect(0,0,100,100); g.setColor(Color.white); g.fillRect(150,600,250,25); g.fillRect(550,600,250,25); g.fillRect(950,600,250,25); g.setColor(Color.red); g.fillRect(270,325,10,275); g.fillRect(270+400,325,10,275); g.fillRect(270+800,325,10,275); int x, y,top=0; g.setColor(Color.yellow); x=150;y=580; for(int ii:stacks[0]) { g.fillRect(x+((ii*125)/10),y-(((ii)*250)/10),((10-ii)*250)/10,20);} x=550;y=580; for(int ii:stacks[1]) {g.fillRect(x+((ii*125)/10),y-(((ii)*250)/10),((10-ii)*250)/10,20);} x=950;y=580; for(int ii:stacks[2]) {g.fillRect(x+((ii*125)/10),y-(((ii)*250)/10),((10-ii)*250)/10,20);} System.out.println("ENTRO"); setOpaque(false); } private class play implements ActionListener //manual { public void actionPerformed(ActionEvent algo) { parar=false; if(primera=true) { hanoi(0,2,no); primera=false; } } } private class stop implements ActionListener //manual { public void actionPerformed(ActionEvent algo) { parar=true; } } private class vel implements ActionListener //manual { public void actionPerformed(ActionEvent algo) { if (velocidad.getSelectedItem()=="Lenta") {tiempo=150;} else if (velocidad.getSelectedItem()=="Intermedia") {tiempo=75;} else tiempo=50; ok2.setVisible(false); jugar.setVisible(true); nojugar.setVisible(true); } } private class a implements ActionListener //auto { public void actionPerformed(ActionEvent algo) { auto.setVisible(false); info.setVisible(true); numeros.setVisible(true); ok.setVisible(true); op=3; } } private class okiz implements ActionListener //ok { public void actionPerformed(ActionEvent algo) { no=Integer.parseInt(numeros.getSelectedItem().toString()); piezas=no; if (no>0 && no<11) { info.setVisible(false); numeros.setVisible(false); ok.setVisible(false); for (int i=no;i>0;i--) stacks[0].push(i); opcion=2; if (op==3) { info.setText("Velocidad: ");info.setVisible(true); velocidad.setVisible(true); ok2.setVisible(true); } } else { } repaint(); } } } the code of the other class that calls the one up is below: import java.awt.*; import java.io.*; import java.net.URL; import javax.imageio.*; import javax.swing.*; import javax.swing.border.*; import java.lang.*; import java.awt.event.*; public class aaa extends JPanel { private ImageIcon Background; private JLabel fondo; public static void main(String[] args) throws IOException { JFrame.setDefaultLookAndFeelDecorated(true); final JPanel cp = new JPanel(new BorderLayout()); JFrame frame = new JFrame ("Torres de Hanoi"); frame.setDefaultCloseOperation (JFrame.EXIT_ON_CLOSE); frame.setSize(550,550); frame.setVisible(true); bbb panel = new bbb(); frame.getContentPane().add(panel); frame.pack(); frame.setVisible(true); } }

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  • Oracle Support Master Note for Troubleshooting Advanced Queuing and Oracle Streams Propagation Issues (Doc ID 233099.1)

    - by faye.todd(at)oracle.com
    Master Note for Troubleshooting Advanced Queuing and Oracle Streams Propagation Issues (Doc ID 233099.1) Copyright (c) 2010, Oracle Corporation. All Rights Reserved. In this Document  Purpose  Last Review Date  Instructions for the Reader  Troubleshooting Details     1. Scope and Application      2. Definitions and Classifications     3. How to Use This Guide     4. Basic AQ Propagation Troubleshooting     5. Additional Troubleshooting Steps for AQ Propagation of User-Enqueued and Dequeued Messages     6. Additional Troubleshooting Steps for Propagation in an Oracle Streams Environment     7. Performance Issues  References Applies to: Oracle Server - Enterprise Edition - Version: 8.1.7.0 to 11.2.0.2 - Release: 8.1.7 to 11.2Information in this document applies to any platform. Purpose This document presents a step-by-step methodology for troubleshooting and resolving problems with Advanced Queuing Propagation in both Streams and basic Advanced Queuing environments. It also serves as a master reference for other more specific notes on Oracle Streams Propagation and Advanced Queuing Propagation issues. Last Review Date December 20, 2010 Instructions for the Reader A Troubleshooting Guide is provided to assist in debugging a specific issue. When possible, diagnostic tools are included in the document to assist in troubleshooting. Troubleshooting Details 1. Scope and Application This note is intended for Database Administrators of Oracle databases where issues are being encountered with propagating messages between advanced queues, whether the queues are used for user-created messaging systems or for Oracle Streams. It contains troubleshooting steps and links to notes for further problem resolution.It can also be used a template to document a problem when it is necessary to engage Oracle Support Services. Knowing what is NOT happening can frequently speed up the resolution process by focusing solely on the pertinent problem area. This guide is divided into five parts: Section 2: Definitions and Classifications (discusses the different types and features of propagations possible - helpful for understanding the rest of the guide) Section 3: How to Use this Guide (to be used as a start part for determining the scope of the problem and what sections to consult) Section 4. Basic AQ propagation troubleshooting (applies to both AQ propagation of user enqueued and dequeued messages as well as Oracle Streams propagations) Section 5. Additional troubleshooting steps for AQ propagation of user enqueued and dequeued messages Section 6. Additional troubleshooting steps for Oracle Streams propagation Section 7. Performance issues 2. Definitions and Classifications Given the potential scope of issues that can be encountered with AQ propagation, the first recommended step is to do some basic diagnosis to determine the type of problem that is being encountered. 2.1. What Type of Propagation is Being Used? 2.1.1. Buffered Messaging For an advanced queue, messages can be maintained on disk (persistent messaging) or in memory (buffered messaging). To determine if a queue is buffered or not, reference the GV_$BUFFERED_QUEUES view. If the queue does not appear in this view, it is persistent. 2.1.2. Propagation mode - queue-to-dblink vs queue-to-queue As of 10.2, an AQ propagation can also be defined as queue-to-dblink, or queue-to-queue: queue-to-dblink: The propagation delivers messages or events from the source queue to all subscribing queues at the destination database identified by the dblink. A single propagation schedule is used to propagate messages to all subscribing queues. Hence any changes made to this schedule will affect message delivery to all the subscribing queues. This mode does not support multiple propagations from the same source queue to the same target database. queue-to-queue: Added in 10.2, this propagation mode delivers messages or events from the source queue to a specific destination queue identified on the database link. This allows the user to have fine-grained control on the propagation schedule for message delivery. This new propagation mode also supports transparent failover when propagating to a destination Oracle RAC system. With queue-to-queue propagation, you are no longer required to re-point a database link if the owner instance of the queue fails on Oracle RAC. This mode supports multiple propagations to the same target database if the target queues are different. The default is queue-to-dblink. To verify if queue-to-queue propagation is being used, in non-Streams environments query DBA_QUEUE_SCHEDULES.DESTINATION - if a remote queue is listed along with the remote database link, then queue-to-queue propagation is being used. For Streams environments, the DBA_PROPAGATION.QUEUE_TO_QUEUE column can be checked.See the following note for a method to switch between the two modes:Document 827473.1 How to alter propagation from queue-to-queue to queue-to-dblink 2.1.3. Combined Capture and Apply (CCA) for Streams In 11g Oracle Streams environments, an optimization called Combined Capture and Apply (CCA) is implemented by default when possible. Although a propagation is configured in this case, Streams does not use it; instead it passes information directly from capture to an apply receiver. To see if CCA is in use: COLUMN CAPTURE_NAME HEADING 'Capture Name' FORMAT A30COLUMN OPTIMIZATION HEADING 'CCA Mode?' FORMAT A10SELECT CAPTURE_NAME, DECODE(OPTIMIZATION,0, 'No','Yes') OPTIMIZATIONFROM V$STREAMS_CAPTURE; Also, see the following note:Document 463820.1 Streams Combined Capture and Apply in 11g 2.2. Queue Table Compatibility There are three types of queue table compatibility. In more recent databases, queue tables may be present in all three modes of compatibility: 8.0 - earliest version, deprecated in 10.2 onwards 8.1 - support added for RAC, asynchronous notification, secure queues, queue level access control, rule-based subscribers, separate storage of history information 10.0 - if the database is in 10.1-compatible mode, then the default value for queue table compatibility is 10.0 2.3. Single vs Multiple Consumer Queue Tables If more than one recipient can dequeue a message from a queue, then its queue table is multiple consumer. You can propagate messages from a multiple-consumer queue to a single-consumer queue. Propagation from a single-consumer queue to a multiple-consumer queue is not possible. 3. How to Use This Guide 3.1. Are Messages Being Propagated at All, or is the Propagation Just Slow? Run the following query on the source database for the propagation (assuming that it is running): select TOTAL_NUMBER from DBA_QUEUE_SCHEDULES where QNAME='<source_queue_name>'; If TOTAL_NUMBER is increasing, then propagation is most likely functioning, although it may be slow. For performance issues, see Section 7. 3.2. Propagation Between Persistent User-Created Queues See Sections 4 and 5 (and optionally Section 6 if performance is an issue). 3.3. Propagation Between Buffered User-Created Queues See Sections 4, 5, and 6 (and optionally Section 7 if performance is an issue). 3.4. Propagation between Oracle Streams Queues (without Combined Capture and Apply (CCA) Optimization) See Sections 4 and 6 (and optionally Section 7 if performance is an issue). 3.5. Propagation between Oracle Streams Queues (with Combined Capture and Apply (CCA) Optimization) Although an AQ propagation is not used directly in this case, some characteristics of the message transfer are inferred from the propagation parameters used. Some parts of Sections 4 and 6 still apply. 3.6. Messaging Gateway Propagations This note does not apply to Messaging Gateway propagations. 4. Basic AQ Propagation Troubleshooting 4.1. Double-check Your Code Make sure that you are consistent in your usage of the database link(s) names, queue names, etc. It may be useful to plot a diagram of which queues are connected via which database links to make sure that the logical structure is correct. 4.2. Verify that Job Queue Processes are Running 4.2.1. Versions 10.2 and Lower - DBA_JOBS Package For versions 10.2 and lower, a scheduled propagation is managed by DBMS_JOB package. The propagation is performed by job queue process background processes. Therefore we need to verify that there are sufficient processes available for the propagation process. We should have at least 4 job queue processes running and preferably more depending on the number of other jobs running in the database. It should be noted that for AQ specific work, AQ will only ever use half of the job queue processes available.An issue caused by an inadequate job queue processes parameter setting is described in the following note:Document 298015.1 Kwqjswproc:Excep After Loop: Assigning To Self 4.2.1.1. Job Queue Processes in Initalization Parameter File The parameter JOB_QUEUE_PROCESSES in the init.ora/spfile should be > 0. The value can be changed dynamically via connect / as sysdbaalter system set JOB_QUEUE_PROCESSES=10; 4.2.1.2. Job Queue Processes in Memory The following command will show how many job queue processes are currentlyin use by this instance (this may be different than what is in the init.ora/spfile): connect / as sysdbashow parameter job; 4.2.1.3. OS PIDs Corresponding to Job Queue Processes Identify the operating system process ids (spids) of job queue processes involved in propagation via select p.SPID, p.PROGRAM from V$PROCESS p, DBA_JOBS_RUNNING jr, V$SESSION s, DBA_JOBS j where s.SID=jr.SID and s.PADDR=p.ADDR and jr.JOB=j.JOBand j.WHAT like '%sys.dbms_aqadm.aq$_propaq(job)%'; and these SPIDs can be used to check at the operating system level that they exist.In 8i a job queue process will have a name similar to: ora_snp1_<instance_name>.In 9i onwards you will see a coordinator process: ora_cjq0_ and multiple slave processes: ora_jnnn_<instance_name>, where nnn is an integer between 1 and 999. 4.2.2. Version 11.1 and Above - Oracle Scheduler In version 11.1 and above, Oracle Scheduler is used to perform AQ and Streams propagations. Oracle Scheduler automatically tunes the number of slave processes for these jobs based on the load on the computer system, and the JOB_QUEUE_PROCESSES initialization parameter is only used to specify the maximum number of slave processes. Therefore, the JOB_QUEUE_PROCESSES initialization parameter does not need to be set (it defaults to a very high number), unless you want to limit the number of slaves that can be created. If JOB_QUEUE_PROCESSES = 0, no propagation jobs will run.See the following note for a discussion of Oracle Streams 11g and Oracle Scheduler:Document 1083608.1 11g Streams and Oracle Scheduler 4.2.2.1. Job Queue Processes in Initalization Parameter File The parameter JOB_QUEUE_PROCESSES in the init.ora/spfile should be > 0, and preferably be left at its default value. The value can be changed dynamically via connect / as sysdbaalter system set JOB_QUEUE_PROCESSES=10; To set the JOB_QUEUE_PROCESSES parameter to its default value, run: connect / as sysdbaalter system reset JOB_QUEUE_PROCESSES; and then bounce the instance. 4.2.2.2. Job Queue Processes in Memory The following command will show how many job queue processes are currently in use by this instance (this may be different than what is in the init.ora/spfile): connect / as sysdbashow parameter job; 4.2.2.3. OS PIDs Corresponding to Job Queue Processes Identify the operating system process ids (SPIDs) of job queue processes involved in propagation via col PROGRAM for a30select p.SPID, p.PROGRAM, j.JOB_namefrom v$PROCESS p, DBA_SCHEDULER_RUNNING_JOBS jr, V$SESSION s, DBA_SCHEDULER_JOBS j where s.SID=jr.SESSION_ID and s.PADDR=p.ADDRand jr.JOB_name=j.JOB_NAME and j.JOB_NAME like '%AQ_JOB$_%'; and these SPIDs can be used to check at the operating system level that they exist.You will see a coordinator process: ora_cjq0_ and multiple slave processes: ora_jnnn_<instance_name>, where nnn is an integer between 1 and 999. 4.3. Check the Alert Log and Any Associated Trace Files The first place to check for propagation failures is the alert logs at all sites (local and if relevant all remote sites). When a job queue process attempts to execute a schedule and fails it will always write an error stack to the alert log. This error stack will also be written in a job queue process trace file, which will be written to the BACKGROUND_DUMP_DEST location for 10.2 and below, and in the DIAGNOSTIC_DEST location for 11g. The fact that errors are written to the alert log demonstrates that the schedule is executing. This means that the problem could be with the set up of the schedule. In this example the ORA-02068 demonstrates that the failure was at the remote site. Further investigation revealed that the remote database was not open, hence the ORA-03114 error. Starting the database resolved the problem. Thu Feb 14 10:40:05 2002 Propagation Schedule for (AQADM.MULTIPLEQ, SHANE816.WORLD) encountered following error:ORA-04052: error occurred when looking up Remote object [email protected]: error occurred at recursive SQL level 4ORA-02068: following severe error from SHANE816ORA-03114: not connected to ORACLEORA-06512: at "SYS.DBMS_AQADM_SYS", line 4770ORA-06512: at "SYS.DBMS_AQADM", line 548ORA-06512: at line 1 Other potential errors that may be written to the alert log can be found in the following notes:Document 827184.1 AQ Propagation with CLOB data types Fails with ORA-22990 (11.1)Document 846297.1 AQ Propagation Fails : ORA-00600[kope2upic2954] or Ora-00600[Kghsstream_copyn] (10.2, 11.1)Document 731292.1 ORA-25215 Reported on Local Propagation When Using Transformation with ANYDATA queue tables (10.2, 11.1, 11.2)Document 365093.1 ORA-07445 [kwqppay2aqe()+7360] Reported on Propagation of a Transformed Message (10.1, 10.2)Document 219416.1 Advanced Queuing Propagation Fails with ORA-22922 (9.0)Document 1203544.1 AQ Propagation Aborted with ORA-600 [ociksin: invalid status] on SYS.DBMS_AQADM_SYS.AQ$_PROPAGATION_PROCEDURE After Upgrade (11.1, 11.2)Document 1087324.1 ORA-01405 ORA-01422 reported by Advanced Queuing Propagation schedules after RAC reconfiguration (10.2)Document 1079577.1 Advanced Queuing Propagation Fails With "ORA-22370 incorrect usage of method" (9.2, 10.2, 11.1, 11.2)Document 332792.1 ORA-04061 error relating to SYS.DBMS_PRVTAQIP reported when setting up Statspack (8.1, 9.0, 9.2, 10.1)Document 353325.1 ORA-24056: Internal inconsistency for QUEUE <queue_name> and destination <dblink> (8.1, 9.0, 9.2, 10.1, 10.2, 11.1, 11.2)Document 787367.1 ORA-22275 reported on Propagating Messages with LOB component when propagating between 10.1 and 10.2 (10.1, 10.2)Document 566622.1 ORA-22275 when propagating >4K AQ$_JMS_TEXT_MESSAGEs from 9.2.0.8 to 10.2.0.1 (9.2, 10.1)Document 731539.1 ORA-29268: HTTP client error 401 Unauthorized Error when the AQ Servlet attempts to Propagate a message via HTTP (9.0, 9.2, 10.1, 10.2, 11.1)Document 253131.1 Concurrent Writes May Corrupt LOB Segment When Using Auto Segment Space Management (ORA-1555) (9.2)Document 118884.1 How to unschedule a propagation schedule stuck in pending stateDocument 222992.1 DBMS_AQADM.DISABLE_PROPAGATION_SCHEDULE Returns ORA-24082Document 282987.1 Propagated Messages marked UNDELIVERABLE after Drop and Recreate Of Remote QueueDocument 1204080.1 AQ Propagation Failing With ORA-25329 After Upgraded From 8i or 9i to 10g or 11g.Document 1233675.1 AQ Propagation stops after upgrade to 11.2.0.1 ORA-30757 4.3.1. Errors Related to Incorrect Network Configuration The most common propagation errors result from an incorrect network configuration. The list below contains common errors caused by tnsnames.ora file or database links being configured incorrectly: - ORA-12154: TNS:could not resolve service name- ORA-12505: TNS:listener does not currently know of SID given in connect descriptor- ORA-12514: TNS:listener could not resolve SERVICE_NAME - ORA-12541: TNS-12541 TNS:no listener 4.4. Check the Database Links Exist and are Functioning Correctly For schedules to remote databases confirm the database link exists via. SQL> col DBLINK for a45SQL> select QNAME, NVL(REGEXP_SUBSTR(DESTINATION, '[^@]+', 1, 2), DESTINATION) dblink2 from DBA_QUEUE_SCHEDULES3 where MESSAGE_DELIVERY_MODE = 'PERSISTENT';QNAME DBLINK------------------------------ ---------------------------------------------MY_QUEUE ORCL102B.WORLD Connect as the owner of the link and select across it to verify it works and connects to the database we expect. i.e. select * from ALL_QUEUES@ ORCL102B.WORLD; You need to ensure that the userid that scheduled the propagation (using DBMS_AQADM.SCHEDULE_PROPAGATION or DBMS_PROPAGATION_ADM.CREATE_PROPAGATION if using Streams) has access to the database link for the destination. 4.5. Has Propagation Been Correctly Scheduled? Check that the propagation schedule has been created and that a job queue process has been assigned. Look for the entry in DBA_QUEUE_SCHEDULES and SYS.AQ$_SCHEDULES for your schedule. For 10g and below, check that it has a JOBNO entry in SYS.AQ$_SCHEDULES, and that there is an entry in DBA_JOBS with that JOBNO. For 11g and above, check that the schedule has a JOB_NAME entry in SYS.AQ$_SCHEDULES, and that there is an entry in DBA_SCHEDULER_JOBS with that JOB_NAME. Check the destination is as intended and spelled correctly. SQL> select SCHEMA, QNAME, DESTINATION, SCHEDULE_DISABLED, PROCESS_NAME from DBA_QUEUE_SCHEDULES;SCHEMA QNAME DESTINATION S PROCESS------- ---------- ------------------ - -----------AQADM MULTIPLEQ AQ$_LOCAL N J000 AQ$_LOCAL in the destination column shows that the queue to which we are propagating to is in the same database as the source queue. If the propagation was to a remote (different) database, a database link will be in the DESTINATION column. The entry in the SCHEDULE_DISABLED column, N, means that the schedule is NOT disabled. If Y (yes) appears in this column, propagation is disabled and the schedule will not be executed. If not using Oracle Streams, propagation should resume once you have enabled the schedule by invoking DBMS_AQADM.ENABLE_PROPAGATION_SCHEDULE (for 10.2 Oracle Streams and above, the DBMS_PROPAGATION_ADM.START_PROPAGATION procedure should be used). The PROCESS_NAME is the name of the job queue process currently allocated to execute the schedule. This process is allocated dynamically at execution time. If the PROCESS_NAME column is null (empty) the schedule is not currently executing. You may need to execute this statement a number of times to verify if a process is being allocated. If a process is at some time allocated to the schedule, it is attempting to execute. SQL> select SCHEMA, QNAME, LAST_RUN_DATE, NEXT_RUN_DATE from DBA_QUEUE_SCHEDULES;SCHEMA QNAME LAST_RUN_DATE NEXT_RUN_DATE------ ----- ----------------------- ----------------------- AQADM MULTIPLEQ 13-FEB-2002 13:18:57 13-FEB-2002 13:20:30 In 11g, these dates are expressed in TIMESTAMP WITH TIME ZONE datatypes. If the NEXT_RUN_DATE and NEXT_RUN_TIME columns are null when this statement is executed, the scheduled propagation is currently in progress. If they never change it would suggest that the schedule itself is never executing. If the next scheduled execution is too far away, change the NEXT_TIME parameter of the schedule so that schedules are executed more frequently (assuming that the window is not set to be infinite). Parameters of a schedule can be changed using the DBMS_AQADM.ALTER_PROPAGATION_SCHEDULE call. In 10g and below, scheduling propagation posts a job in the DBA_JOBS view. The columns are more or less the same as DBA_QUEUE_SCHEDULES so you just need to recognize the job and verify that it exists. SQL> select JOB, WHAT from DBA_JOBS where WHAT like '%sys.dbms_aqadm.aq$_propaq(job)%';JOB WHAT---- ----------------- 720 next_date := sys.dbms_aqadm.aq$_propaq(job); For 11g, scheduling propagation posts a job in DBA_SCHEDULER_JOBS instead: SQL> select JOB_NAME from DBA_SCHEDULER_JOBS where JOB_NAME like 'AQ_JOB$_%';JOB_NAME------------------------------AQ_JOB$_41 If no job exists, check DBA_QUEUE_SCHEDULES to make sure that the schedule has not been disabled. For 10g and below, the job number is dynamic for AQ propagation schedules. The procedure that is executed to expedite a propagation schedule runs, removes itself from DBA_JOBS, and then reposts a new job for the next scheduled propagation. The job number should therefore always increment unless the schedule has been set up to run indefinitely. 4.6. Is the Schedule Executing but Failing to Complete? Run the following query: SQL> select FAILURES, LAST_ERROR_MSG from DBA_QUEUE_SCHEDULES;FAILURES LAST_ERROR_MSG------------ -----------------------1 ORA-25207: enqueue failed, queue AQADM.INQ is disabled from enqueueingORA-02063: preceding line from SHANE816 The failures column shows how many times we have attempted to execute the schedule and failed. Oracle will attempt to execute the schedule 16 times after which it will be removed from the DBA_JOBS or DBA_SCHEDULER_JOBS view and the schedule will become disabled. The column DBA_QUEUE_SCHEDULES.SCHEDULE_DISABLED will show 'Y'. For 11g and above, the DBA_SCHEDULER_JOBS.STATE column will show 'BROKEN' for the job corresponding to DBA_QUEUE_SCHEDULES.JOB_NAME. Prior to 10g the back off algorithm for failures was exponential, whereas from 10g onwards it is linear. The propagation will become disabled on the 17th attempt. Only the last execution failure will be reflected in the LAST_ERROR_MSG column. That is, if the schedule fails 5 times for 5 different reasons, only the last set of errors will be recorded in DBA_QUEUE_SCHEDULES. Any errors need to be resolved to allow propagation to continue. If propagation has also become disabled due to 17 failures, first resolve the reason for the error and then re-enable the schedule using the DBMS_AQADM.ENABLE_PROPAGATION_SCHEDULE procedure, or DBMS_PROPAGATION_ADM.START_PROPAGATION if using 10.2 or above Oracle Streams. As soon as the schedule executes successfully the error message entries will be deleted. Oracle does not keep a history of past failures. However, when using Oracle Streams, the errors will be retained in the DBA_PROPAGATION view even after the schedule resumes successfully. See the following note for instructions on how to clear out the errors from the DBA_PROPAGATION view:Document 808136.1 How to clear the old errors from DBA_PROPAGATION view?If a schedule is active and no errors are being reported then the source queue may not have any messages to be propagated. 4.7. Do the Propagation Notification Queue Table and Queue Exist? Check to see that the propagation notification queue table and queue exist and are enabled for enqueue and dequeue. Propagation makes use of the propagation notification queue for handling propagation run-time events, and the messages in this queue are stored in a SYS-owned queue table. This queue should never be stopped or dropped and the corresponding queue table never be dropped. 10g and belowThe propagation notification queue table is of the format SYS.AQ$_PROP_TABLE_n, where 'n' is the RAC instance number, i.e. '1' for a non-RAC environment. This queue and queue table are created implicitly when propagation is first scheduled. If propagation has been scheduled and these objects do not exist, try unscheduling and rescheduling propagation. If they still do not exist contact Oracle Support. SQL> select QUEUE_TABLE from DBA_QUEUE_TABLES2 where QUEUE_TABLE like '%PROP_TABLE%' and OWNER = 'SYS';QUEUE_TABLE------------------------------AQ$_PROP_TABLE_1SQL> select NAME, ENQUEUE_ENABLED, DEQUEUE_ENABLED2 from DBA_QUEUES where owner='SYS'3 and QUEUE_TABLE like '%PROP_TABLE%';NAME ENQUEUE DEQUEUE------------------------------ ------- -------AQ$_PROP_NOTIFY_1 YES YESAQ$_AQ$_PROP_TABLE_1_E NO NO If the AQ$_PROP_NOTIFY_1 queue is not enabled for enqueue or dequeue, it should be so enabled using DBMS_AQADM.START_QUEUE. However, the exception queue AQ$_AQ$_PROP_TABLE_1_E should not be enabled for enqueue or dequeue.11g and aboveThe propagation notification queue table is of the format SYS.AQ_PROP_TABLE, and is created when the database is created. If they do not exist, contact Oracle Support. SQL> select QUEUE_TABLE from DBA_QUEUE_TABLES2 where QUEUE_TABLE like '%PROP_TABLE%' and OWNER = 'SYS';QUEUE_TABLE------------------------------AQ_PROP_TABLESQL> select NAME, ENQUEUE_ENABLED, DEQUEUE_ENABLED2 from DBA_QUEUES where owner='SYS'3 and QUEUE_TABLE like '%PROP_TABLE%';NAME ENQUEUE DEQUEUE------------------------------ ------- -------AQ_PROP_NOTIFY YES YESAQ$_AQ_PROP_TABLE_E NO NO If the AQ_PROP_NOTIFY queue is not enabled for enqueue or dequeue, it should be so enabled using DBMS_AQADM.START_QUEUE. However, the exception queue AQ$_AQ$_PROP_TABLE_E should not be enabled for enqueue or dequeue. 4.8. Does the Remote Queue Exist and is it Enabled for Enqueueing? Check that the remote queue the propagation is transferring messages to exists and is enabled for enqueue: SQL> select DESTINATION from USER_QUEUE_SCHEDULES where QNAME = 'OUTQ';DESTINATION-----------------------------------------------------------------------------"AQADM"."INQ"@M2V102.ESSQL> select OWNER, NAME, ENQUEUE_ENABLED, DEQUEUE_ENABLED from [email protected];OWNER NAME ENQUEUE DEQUEUE-------- ------ ----------- -----------AQADM INQ YES YES 4.9. Do the Target and Source Database Charactersets Differ? If a message fails to propagate, check the database charactersets of the source and target databases. Investigate whether the same message can propagate between the databases with the same characterset or it is only a particular combination of charactersets which causes a problem. 4.10. Check the Queue Table Type Agreement Propagation is not possible between queue tables which have types that differ in some respect. One way to determine if this is the case is to run the DBMS_AQADM.VERIFY_QUEUE_TYPES procedure for the two queues that the propagation operates on. If the types do not agree, DBMS_AQADM.VERIFY_QUEUE_TYPES will return '0'.For AQ propagation between databases which have different NLS_LENGTH_SEMANTICS settings, propagation will not work, unless the queues are Oracle Streams ANYDATA queues.See the following notes for issues caused by lack of type agreement:Document 1079577.1 Advanced Queuing Propagation Fails With "ORA-22370: incorrect usage of method"Document 282987.1 Propagated Messages marked UNDELIVERABLE after Drop and Recreate Of Remote QueueDocument 353754.1 Streams Messaging Propagation Fails between Single and Multi-byte Charactersets when using Chararacter Length Semantics in the ADT 4.11. Enable Propagation Tracing 4.11.1. System Level This is set it in the init.ora/spfile as follows: event="24040 trace name context forever, level 10" and restart the instanceThis event cannot be set dynamically with an alter system command until version 10.2: SQL> alter system set events '24040 trace name context forever, level 10'; To unset the event: SQL> alter system set events '24040 trace name context off'; Debugging information will be logged to job queue trace file(s) (jnnn) as propagation takes place. You can check the trace file for errors, and for statements indicating that messages have been sent. For the most part the trace information is understandable. This trace should also be uploaded to Oracle Support if a service request is created. 4.11.2. Attaching to a Specific Process We can also attach to an existing job queue processes that is running a propagation schedule and trace it individually using the oradebug utility, as follows:10.2 and below connect / as sysdbaselect p.SPID, p.PROGRAM from v$PROCESS p, DBA_JOBS_RUNNING jr, V$SESSION s, DBA_JOBS j where s.SID=jr.SID and s.PADDR=p.ADDR and jr.JOB=j.JOB and j.WHAT like '%sys.dbms_aqadm.aq$_propaq(job)%';-- For the process id (SPID) attach to it via oradebug and generate the following traceoradebug setospid <SPID>oradebug unlimitoradebug Event 10046 trace name context forever, level 12oradebug Event 24040 trace name context forever, level 10-- Trace the process for 5 minutesoradebug Event 10046 trace name context offoradebug Event 24040 trace name context off-- The following command returns the pathname/filename to the file being written tooradebug tracefile_name 11g connect / as sysdbacol PROGRAM for a30select p.SPID, p.PROGRAM, j.JOB_NAMEfrom v$PROCESS p, DBA_SCHEDULER_RUNNING_JOBS jr, V$SESSION s, DBA_SCHEDULER_JOBS j where s.SID=jr.SESSION_ID and s.PADDR=p.ADDR and jr.JOB_NAME=j.JOB_NAME and j.JOB_NAME like '%AQ_JOB$_%';-- For the process id (SPID) attach to it via oradebug and generate the following traceoradebug setospid <SPID>oradebug unlimitoradebug Event 10046 trace name context forever, level 12oradebug Event 24040 trace name context forever, level 10-- Trace the process for 5 minutesoradebug Event 10046 trace name context offoradebug Event 24040 trace name context off-- The following command returns the pathname/filename to the file being written tooradebug tracefile_name 4.11.3. Further Tracing The previous tracing steps only trace the job queue process executing the propagation on the source. At times it is useful to trace the propagation receiver process (the session which is enqueueing the messages into the target queue) on the target database which is associated with the job queue process on the source database.These following queries provide ways of identifying the processes involved in propagation so that you can attach to them via oradebug to generate trace information.In order to identify the propagation receiver process you need to execute the query as a user with privileges to access the v$ views in both the local and remote databases so the database link must connect as a user with those privileges in the remote database. The <DBLINK> in the queries should be replaced by the appropriate database link.The queries have two forms due to the differences between operating systems. The value returned by 'Rem Process' is the operating system identifier of the propagation receiver on the remote database. Once identified, this process can be attached to and traced on the remote database using the commands given in Section 4.11.2.10.2 and below - Windows select pl.SPID "JobQ Process", pl.PROGRAM, sr.PROCESS "Rem Process" from v$PROCESS pl, DBA_JOBS_RUNNING jr, V$SESSION s, DBA_JOBS j, V$SESSION@<DBLINK> sr where s.SID=jr.SID and s.PADDR=pl.ADDR and jr.JOB=j.JOB and j.WHAT like '%sys.dbms_aqadm.aq$_propaq(job)%' and pl.SPID=substr(sr.PROCESS, instr(sr.PROCESS,':')+1); 10.2 and below - Unix select pl.SPID "JobQ Process", pl.PROGRAM, sr.PROCESS "Rem Process" from V$PROCESS pl, DBA_JOBS_RUNNING jr, V$SESSION s, DBA_JOBS j, V$SESSION@<DBLINK> sr where s.SID=jr.SID and s.PADDR=pl.ADDR and jr.JOB=j.JOB and j.WHAT like '%sys.dbms_aqadm.aq$_propaq(job)%' and pl.SPID=sr.PROCESS; 11g - Windows select pl.SPID "JobQ Process", pl.PROGRAM, sr.PROCESS "Rem Process" from V$PROCESS pl, DBA_SCHEDULER_RUNNING_JOBS jr, V$SESSION s, DBA_SCHEDULER_JOBS j, V$SESSION@<DBLINK> sr where s.SID=jr.SESSION_ID and s.PADDR=pl.ADDR and jr.JOB_NAME=j.JOB_NAME and j.JOB_NAME like '%AQ_JOB$_%%' and pl.SPID=substr(sr.PROCESS, instr(sr.PROCESS,':')+1); 11g - Unix select pl.SPID "JobQ Process", pl.PROGRAM, sr.PROCESS "Rem Process" from V$PROCESS pl, DBA_SCHEDULER_RUNNING_JOBS jr, V$SESSION s, DBA_SCHEDULER_JOBS j, V$SESSION@<DBLINK> sr where s.SID=jr.SESSION_ID and s.PADDR=pl.ADDR and jr.JOB_NAME=j.JOB_NAME and j.JOB_NAME like '%AQ_JOB$_%%' and pl.SPID=sr.PROCESS;   5. Additional Troubleshooting Steps for AQ Propagation of User-Enqueued and Dequeued Messages 5.1. Check the Privileges of All Users Involved Ensure that the owner of the database link has the necessary privileges on the aq packages. SQL> select TABLE_NAME, PRIVILEGE from USER_TAB_PRIVS;TABLE_NAME PRIVILEGE------------------------------ ----------------------------------------DBMS_LOCK EXECUTEDBMS_AQ EXECUTEDBMS_AQADM EXECUTEDBMS_AQ_BQVIEW EXECUTEQT52814_BUFFER SELECT Note that when queue table is created, a view called QT<nnn>_BUFFER is created in the SYS schema, and the queue table owner is given SELECT privileges on it. The <nnn> corresponds to the object_id of the associated queue table. SQL> select * from USER_ROLE_PRIVS;USERNAME GRANTED_ROLE ADM DEF OS_------------------------------ ------------------------------ ---- ---- ---AQ_USER1 AQ_ADMINISTRATOR_ROLE NO YES NOAQ_USER1 CONNECT NO YES NOAQ_USER1 RESOURCE NO YES NO It is good practice to configure central AQ administrative user. All admin and processing jobs are created, executed and administered as this user. This configuration is not mandatory however, and the database link can be owned by any existing queue user. If this latter configuration is used, ensure that the connecting user has the necessary privileges on the AQ packages and objects involved. Privileges for an AQ Administrative user Execute on DBMS_AQADM Execute on DBMS_AQ Granted the AQ_ADMINISTRATOR_ROLE Privileges for an AQ user Execute on DBMS_AQ Execute on the message payload Enqueue privileges on the remote queue Dequeue privileges on the originating queue Privileges need to be confirmed on both sites when propagation is scheduled to remote destinations. Verify that the user ID used to login to the destination through the database link has been granted privileges to use AQ. 5.2. Verify Queue Payload Types AQ will not propagate messages from one queue to another if the payload types of the two queues are not verified to be equivalent. An AQ administrator can verify if the source and destination's payload types match by executing the DBMS_AQADM.VERIFY_QUEUE_TYPES procedure. The results of the type checking will be stored in the SYS.AQ$_MESSAGE_TYPES table. This table can be accessed using the object identifier OID of the source queue and the address database link of the destination queue, i.e. [schema.]queue_name[@destination]. Prior to Oracle 9i the payload (message type) had to be the same for all the queue tables involved in propagation. From Oracle9i onwards a transformation can be used so that payloads can be converted from one type to another. The following procedural call made on the source database can verify whether we can propagate between the source and the destination queue tables. connect aq_user1/[email protected] serverout onDECLARErc_value number;BEGINDBMS_AQADM.VERIFY_QUEUE_TYPES(src_queue_name => 'AQ_USER1.Q_1', dest_queue_name => 'AQ_USER2.Q_2',destination => 'dbl_aq_user2.es',rc => rc_value);dbms_output.put_line('rc_value code is '||rc_value);END;/ If propagation is possible then the return code value will be 1. If it is 0 then propagation is not possible and further investigation of the types and transformations used by and in conjunction with the queue tables is required. With regard to comparison of the types the following sql can be used to extract the DDL for a specific type with' %' changed appropriately on the source and target. This can then be compared for the source and target. SET LONG 20000 set pagesize 50 EXECUTE DBMS_METADATA.SET_TRANSFORM_PARAM(DBMS_METADATA.SESSION_TRANSFORM, 'STORAGE',false); SELECT DBMS_METADATA.GET_DDL('TYPE',t.type_name) from user_types t WHERE t.type_name like '%'; EXECUTE DBMS_METADATA.SET_TRANSFORM_PARAM(DBMS_METADATA.SESSION_TRANSFORM, 'DEFAULT'); 5.3. Check Message State and Destination The first step in this process is to identify the queue table associated with the problem source queue. Although you schedule propagation for a specific queue, most of the meta-data associated with that queue is stored in the underlying queue table. The following statement finds the queue table for a given queue (note that this is a multiple-consumer queue table). SQL> select QUEUE_TABLE from DBA_QUEUES where NAME = 'MULTIPLEQ';QUEUE_TABLE --------------------MULTIPLEQTABLE For a small amount of messages in a multiple-consumer queue table, the following query can be run: SQL> select MSG_STATE, CONSUMER_NAME, ADDRESS from AQ$MULTIPLEQTABLE where QUEUE = 'MULTIPLEQ';MSG_STATE CONSUMER_NAME ADDRESS-------------- ----------------------- -------------READY AQUSER2 [email protected] AQUSER1READY AQUSER3 AQADM.INQ In this example we see 2 messages ready to be propagated to remote queues and 1 that is not. If the address column is blank, the message is not scheduled for propagation and can only be dequeued from the queue upon which it was enqueued. The MSG_STATE column values are discussed in Document 102330.1 Advanced Queueing MSG_STATE Values and their Interpretation. If the address column has a value, the message has been enqueued for propagation to another queue. The first row in the example includes a database link (@M2V102.ES). This demonstrates that the message should be propagated to a queue at a remote database. The third row does not include a database link so will be propagated to a queue that resides on the same database as the source queue. The consumer name is the intended recipient at the target queue. Note that we are not querying the base queue table directly; rather, we are querying a view that is available on top of every queue table, AQ$<queue_table_name>.A more realistic query in an environment where the queue table contains thousands of messages is8.0.3-compatible multiple-consumer queue table and all compatibility single-consumer queue tables select count(*), MSG_STATE, QUEUE from AQ$<queue_table_name>  group by MSG_STATE, QUEUE; 8.1.3 and 10.0-compatible queue tables select count(*), MSG_STATE, QUEUE, CONSUMER_NAME from AQ$<queue_table_name>group by MSG_STATE, QUEUE, CONSUMER_NAME; For multiple-consumer queue tables, if you did not see the expected CONSUMER_NAME , check the syntax of the enqueue code and verify the recipients are declared correctly. If a recipients list is not used on enqueue, check the subscriber list in the AQ$_<queue_table_name>_S view (note that a single-consumer queue table does not have a subscriber view. This view records all members of the default subscription list which were added using the DBMS_AQADM.ADD_SUBSCRIBER procedure and also those enqueued using a recipient list. SQL> select QUEUE, NAME, ADDRESS from AQ$MULTIPLEQTABLE_S;QUEUE NAME ADDRESS---------- ----------- -------------MULTIPLEQ AQUSER2 [email protected] AQUSER1 In this example we have 2 subscribers registered with the queue. We have a local subscriber AQUSER1, and a remote subscriber AQUSER2, on the queue INQ, owned by AQADM, at M2V102.ES. Unless overridden with a recipient list during enqueue every message enqueued to this queue will be propagated to INQ at M2V102.ES.For 8.1 style and above multiple consumer queue tables, you can also check the following information at the target: select CONSUMER_NAME, DEQ_TXN_ID, DEQ_TIME, DEQ_USER_ID, PROPAGATED_MSGID from AQ$<queue_table_name> where QUEUE = '<QUEUE_NAME>'; For 8.0 style queues, if the queue table supports multiple consumers you can obtain the same information from the history column of the queue table: select h.CONSUMER, h.TRANSACTION_ID, h.DEQ_TIME, h.DEQ_USER, h.PROPAGATED_MSGIDfrom AQ$<queue_table_name> t, table(t.history) h where t.Q_NAME = '<QUEUE_NAME>'; A non-NULL TRANSACTION_ID indicates that the message was successfully propagated. Further, the DEQ_TIME indicates the time of propagation, the DEQ_USER indicates the userid used for propagation, and the PROPAGATED_MSGID indicates the message ID of the message that was enqueued at the destination. 6. Additional Troubleshooting Steps for Propagation in an Oracle Streams Environment 6.1. Is the Propagation Enabled? For a propagation job to propagate messages, the propagation must be enabled. For Streams, a special view called DBA_PROPAGATION exists to convey information about Streams propagations. If messages are not being propagated by a propagation as expected, then the propagation might not be enabled. To query for this: SELECT p.PROPAGATION_NAME, DECODE(s.SCHEDULE_DISABLED, 'Y', 'Disabled','N', 'Enabled') SCHEDULE_DISABLED, s.PROCESS_NAME, s.FAILURES, s.LAST_ERROR_MSGFROM DBA_QUEUE_SCHEDULES s, DBA_PROPAGATION pWHERE p.DESTINATION_DBLINK = NVL(REGEXP_SUBSTR(s.DESTINATION, '[^@]+', 1, 2), s.DESTINATION) AND s.SCHEMA = p.SOURCE_QUEUE_OWNER AND s.QNAME = p.SOURCE_QUEUE_NAME AND MESSAGE_DELIVERY_MODE = 'PERSISTENT' order by PROPAGATION_NAME; At times, the propagation job may become "broken" or fail to start after an error has been encountered or after a database restart. If an error is indicated by the above query, an attempt to disable the propagation and then re-enable it can be made. In the examples below, for the propagation named STRMADMIN_PROPAGATE where the queue name is STREAMS_QUEUE owned by STRMADMIN and the destination database link is ORCL2.WORLD, the commands would be:10.2 and above exec dbms_propagation_adm.stop_propagation('STRMADMIN_PROPAGATE'); exec dbms_propagation_adm.start_propagation('STRMADMIN_PROPAGATE'); If the above does not fix the problem, stop the propagation specifying the force parameter (2nd parameter on stop_propagation) as TRUE: exec dbms_propagation_adm.stop_propagation('STRMADMIN_PROPAGATE',true); exec dbms_propagation_adm.start_propagation('STRMADMIN_PROPAGATE'); The statistics for the propagation as well as any old error messages are cleared when the force parameter is set to TRUE. Therefore if the propagation schedule is stopped with FORCE set to TRUE, and upon restart there is still an error message in DBA_PROPAGATION, then the error message is current.9.2 or 10.1 exec dbms_aqadm.disable_propagation_schedule('STRMADMIN.STREAMS_QUEUE','ORCL2.WORLD'); exec dbms.aqadm.enable_propagation_schedule('STRMADMIN.STREAMS_QUEUE','ORCL2.WORLD'); If the above does not fix the problem, perform an unschedule of propagation and then schedule_propagation: exec dbms_aqadm.unschedule_propagation('STRMADMIN.STREAMS_QUEUE','ORCL2.WORLD'); exec dbms_aqadm.schedule_propagation('STRMADMIN.STREAMS_QUEUE','ORCL2.WORLD'); Typically if the error from the first query in Section 6.1 recurs after restarting the propagation as shown above, further troubleshooting of the error is needed. 6.2. Check Propagation Rule Sets and Transformations Inspect the configuration of the rules in the rule set that is associated with the propagation process to make sure that they evaluate to TRUE as expected. If not, then the object or schema will not be propagated. Remember that when a negative rule evaluates to TRUE, the specified object or schema will not be propagated. Finally inspect any rule-based transformations that are implemented with propagation to make sure they are changing the data in the intended way.The following query shows what rule sets are assigned to a propagation: select PROPAGATION_NAME, RULE_SET_OWNER||'.'||RULE_SET_NAME "Positive Rule Set",NEGATIVE_RULE_SET_OWNER||'.'||NEGATIVE_RULE_SET_NAME "Negative Rule Set"from DBA_PROPAGATION; The next two queries list the propagation rules and their conditions. The first is for the positive rule set, the second is for the negative rule set: set long 4000select rsr.RULE_SET_OWNER||'.'||rsr.RULE_SET_NAME RULE_SET ,rsr.RULE_OWNER||'.'||rsr.RULE_NAME RULE_NAME,r.RULE_CONDITION CONDITION fromDBA_RULE_SET_RULES rsr, DBA_RULES rwhere rsr.RULE_NAME = r.RULE_NAME and rsr.RULE_OWNER = r.RULE_OWNER and RULE_SET_NAME in(select RULE_SET_NAME from DBA_PROPAGATION) order by rsr.RULE_SET_OWNER, rsr.RULE_SET_NAME;   set long 4000select c.PROPAGATION_NAME, rsr.RULE_SET_OWNER||'.'||rsr.RULE_SET_NAME RULE_SET ,rsr.RULE_OWNER||'.'||rsr.RULE_NAME RULE_NAME,r.RULE_CONDITION CONDITION fromDBA_RULE_SET_RULES rsr, DBA_RULES r ,DBA_PROPAGATION cwhere rsr.RULE_NAME = r.RULE_NAME and rsr.RULE_OWNER = r.RULE_OWNER andrsr.RULE_SET_OWNER=c.NEGATIVE_RULE_SET_OWNER and rsr.RULE_SET_NAME=c.NEGATIVE_RULE_SET_NAMEand rsr.RULE_SET_NAME in(select NEGATIVE_RULE_SET_NAME from DBA_PROPAGATION) order by rsr.RULE_SET_OWNER, rsr.RULE_SET_NAME; 6.3. Determining the Total Number of Messages and Bytes Propagated As in Section 3.1, determining if messages are flowing can be instructive to see whether the propagation is entirely hung or just slow. If the propagation is not in flow control (see Section 6.5.2), but the statistics are incrementing slowly, there may be a performance issue. For Streams implementations two views are available that can assist with this that can show the number of messages sent by a propagation, as well as the number of acknowledgements being returned from the target site: the V$PROPAGATION_SENDER view at the Source site and the V$PROPAGATION_RECEIVER view at the destination site. It is helpful to query both to determine if messages are being delivered to the target. Look for the statistics to increase.Source: select QUEUE_SCHEMA, QUEUE_NAME, DBLINK,HIGH_WATER_MARK, ACKNOWLEDGEMENT, TOTAL_MSGS, TOTAL_BYTESfrom V$PROPAGATION_SENDER; Target: select SRC_QUEUE_SCHEMA, SRC_QUEUE_NAME, SRC_DBNAME, DST_QUEUE_SCHEMA, DST_QUEUE_NAME, HIGH_WATER_MARK, ACKNOWLEDGEMENT, TOTAL_MSGS from V$PROPAGATION_RECEIVER; 6.4. Check Buffered Subscribers The V$BUFFERED_SUBSCRIBERS view displays information about subscribers for all buffered queues in the instance. This view can be queried to make sure that the site that the propagation is propagating to is listed as a subscriber address for the site being propagated from: select QUEUE_SCHEMA, QUEUE_NAME, SUBSCRIBER_ADDRESS from V$BUFFERED_SUBSCRIBERS; The SUBSCRIBER_ADDRESS column will not be populated when the propagation is local (between queues on the same database). 6.5. Common Streams Propagation Errors 6.5.1. ORA-02082: A loopback database link must have a connection qualifier. This error can occur if you use the Streams Setup Wizard in Oracle Enterprise Manager without first configuring the GLOBAL_NAME for your database. 6.5.2. ORA-25307: Enqueue rate too high. Enable flow control DBA_QUEUE_SCHEDULES will display this informational message for propagation when the automatic flow control (10g feature of Streams) has been invoked.Similar to Streams capture processes, a Streams propagation process can also go into a state of 'flow control. This is an informative message that indicates flow control has been automatically enabled to reduce the rate at which messages are being enqueued into at target queue.This typically occurs when the target site is unable to keep up with the rate of messages flowing from the source site. Other than checking that the apply process is running normally on the target site, usually no action is required by the DBA. Propagation and the capture process will be resumed automatically when the target site is able to accept more messages.The following document contains more information:Document 302109.1 Streams Propagation Error: ORA-25307 Enqueue rate too high. Enable flow controlSee the following document for one potential cause of this situation:Document 1097115.1 Oracle Streams Apply Reader is in 'Paused' State 6.5.3. ORA-25315 unsupported configuration for propagation of buffered messages This error typically occurs when the target database is RAC and usually indicates that an attempt was made to propagate buffered messages with the database link pointing to an instance in the destination database which is not the owner instance of the destination queue. To resolve the problem, use queue-to-queue propagation for buffered messages. 6.5.4. ORA-600 [KWQBMCRCPTS101] after dropping / recreating propagation For cause/fixes refer to:Document 421237.1 ORA-600 [KWQBMCRCPTS101] reported by a Qmon slave process after dropping a Streams Propagation 6.5.5. Stopping or Dropping a Streams Propagation Hangs See the following note:Document 1159787.1 Troubleshooting Streams Propagation When It is Not Functioning and Attempts to Stop It Hang 6.6. Streams Propagation-Related Notes for Common Issues Document 437838.1 Streams Specific PatchesDocument 749181.1 How to Recover Streams After Dropping PropagationDocument 368912.1 Queue to Queue Propagation Schedule encountered ORA-12514 in a RAC environmentDocument 564649.1 ORA-02068/ORA-03114/ORA-03113 Errors From Streams Propagation Process - Remote Database is Available and Unschedule/Reschedule Does Not ResolveDocument 553017.1 Stream Propagation Process Errors Ora-4052 Ora-6554 From 11g To 10201Document 944846.1 Streams Propagation Fails Ora-7445 [kohrsmc]Document 745601.1 ORA-23603 'STREAMS enqueue aborted due to low SGA' Error from Streams Propagation, and V$STREAMS_CAPTURE.STATE Hanging on 'Enqueuing Message'Document 333068.1 ORA-23603: Streams Enqueue Aborted Eue To Low SGADocument 363496.1 Ora-25315 Propagating on RAC StreamsDocument 368237.1 Unable to Unschedule Propagation. Streams Queue is InvalidDocument 436332.1 dbms_propagation_adm.stop_propagation hangsDocument 727389.1 Propagation Fails With ORA-12528Document 730911.1 ORA-4063 Is Reported After Dropping Negative Prop.RulesetDocument 460471.1 Propagation Blocked by Qmon Process - Streams_queue_table / 'library cache lock' waitsDocument 1165583.1 ORA-600 [kwqpuspse0-ack] In Streams EnvironmentDocument 1059029.1 Combined Capture and Apply (CCA) : Capture aborts : ORA-1422 after schedule_propagationDocument 556309.1 Changing Propagation/ queue_to_queue : false -> true does does not work; no LCRs propagatedDocument 839568.1 Propagation failing with error: ORA-01536: space quota exceeded for tablespace ''Document 311021.1 Streams Propagation Process : Ora 12154 After Reboot with Transparent Application Failover TAF configuredDocument 359971.1 STREAMS propagation to Primary of physical Standby configuation errors with Ora-01033, Ora-02068Document 1101616.1 DBMS_PROPAGATION_ADM.DROP_PROPAGATION FAILS WITH ORA-1747 7. Performance Issues A propagation may seem to be slow if the queries from Sections 3.1 and 6.3 show that the message statistics are not changing quickly. In Oracle Streams, this more usually is due to a slow apply process at the target rather than a slow propagation. Propagation could be inferred to be slow if the message statistics are changing, and the state of a capture process according to V$STREAMS_CAPTURE.STATE is PAUSED FOR FLOW CONTROL, but an ORA-25307 'Enqueue rate too high. Enable flow control' warning is NOT observed in DBA_QUEUE_SCHEDULES per Section 6.5.2. If this is the case, see the following notes / white papers for suggestions to increase performance:Document 335516.1 Master Note for Streams Performance RecommendationsDocument 730036.1 Overview for Troubleshooting Streams Performance IssuesDocument 780733.1 Streams Propagation Tuning with Network ParametersWhite Paper: http://www.oracle.com/technetwork/database/features/availability/maa-wp-10gr2-streams-performance-130059.pdfWhite Paper: Oracle Streams Configuration Best Practices: Oracle Database 10g Release 10.2, http://www.oracle.com/technetwork/database/features/availability/maa-10gr2-streams-configuration-132039.pdf, See APPENDIX A: USING STREAMS CONFIGURATIONS OVER A NETWORKFor basic AQ propagation, the network tuning in the aforementioned Appendix A of the white paper 'Oracle Streams Configuration Best Practices: Oracle Database 10g Release 10.2' is applicable. References NOTE:102330.1 - Advanced Queueing MSG_STATE Values and their InterpretationNOTE:102771.1 - Advanced Queueing Propagation using PL/SQLNOTE:1059029.1 - Combined Capture and Apply (CCA) : Capture aborts : ORA-1422 after schedule_propagationNOTE:1079577.1 - Advanced Queuing Propagation Fails With "ORA-22370: incorrect usage of method"NOTE:1083608.1 - 11g Streams and Oracle SchedulerNOTE:1087324.1 - ORA-01405 ORA-01422 reported by Adavanced Queueing Propagation schedules after RAC reconfigurationNOTE:1097115.1 - Oracle Streams Apply Reader is in 'Paused' StateNOTE:1101616.1 - DBMS_PROPAGATION_ADM.DROP_PROPAGATION FAILS WITH ORA-1747NOTE:1159787.1 - Troubleshooting Streams Propagation When It is Not Functioning and Attempts to Stop It HangNOTE:1165583.1 - ORA-600 [kwqpuspse0-ack] In Streams EnvironmentNOTE:118884.1 - How to unschedule a propagation schedule stuck in pending stateNOTE:1203544.1 - AQ PROPAGATION ABORTED WITH ORA-600[OCIKSIN: INVALID STATUS] ON SYS.DBMS_AQADM_SYS.AQ$_PROPAGATION_PROCEDURE AFTER UPGRADENOTE:1204080.1 - AQ Propagation Failing With ORA-25329 After Upgraded From 8i or 9i to 10g or 11g.NOTE:219416.1 - Advanced Queuing Propagation fails with ORA-22922NOTE:222992.1 - DBMS_AQADM.DISABLE_PROPAGATION_SCHEDULE Returns ORA-24082NOTE:253131.1 - Concurrent Writes May Corrupt LOB Segment When Using Auto Segment Space Management (ORA-1555)NOTE:282987.1 - Propagated Messages marked UNDELIVERABLE after Drop and Recreate Of Remote QueueNOTE:298015.1 - Kwqjswproc:Excep After Loop: Assigning To SelfNOTE:302109.1 - Streams Propagation Error: ORA-25307 Enqueue rate too high. Enable flow controlNOTE:311021.1 - Streams Propagation Process : Ora 12154 After Reboot with Transparent Application Failover TAF configuredNOTE:332792.1 - ORA-04061 error relating to SYS.DBMS_PRVTAQIP reported when setting up StatspackNOTE:333068.1 - ORA-23603: Streams Enqueue Aborted Eue To Low SGANOTE:335516.1 - Master Note for Streams Performance RecommendationsNOTE:353325.1 - ORA-24056: Internal inconsistency for QUEUE and destination NOTE:353754.1 - Streams Messaging Propagation Fails between Single and Multi-byte Charactersets when using Chararacter Length Semantics in the ADT.NOTE:359971.1 - STREAMS propagation to Primary of physical Standby configuation errors with Ora-01033, Ora-02068NOTE:363496.1 - Ora-25315 Propagating on RAC StreamsNOTE:365093.1 - ORA-07445 [kwqppay2aqe()+7360] reported on Propagation of a Transformed MessageNOTE:368237.1 - Unable to Unschedule Propagation. Streams Queue is InvalidNOTE:368912.1 - Queue to Queue Propagation Schedule encountered ORA-12514 in a RAC environmentNOTE:421237.1 - ORA-600 [KWQBMCRCPTS101] reported by a Qmon slave process after dropping a Streams PropagationNOTE:436332.1 - dbms_propagation_adm.stop_propagation hangsNOTE:437838.1 - Streams Specific PatchesNOTE:460471.1 - Propagation Blocked by Qmon Process - Streams_queue_table / 'library cache lock' waitsNOTE:463820.1 - Streams Combined Capture and Apply in 11gNOTE:553017.1 - Stream Propagation Process Errors Ora-4052 Ora-6554 From 11g To 10201NOTE:556309.1 - Changing Propagation/ queue_to_queue : false -> true does does not work; no LCRs propagatedNOTE:564649.1 - ORA-02068/ORA-03114/ORA-03113 Errors From Streams Propagation Process - Remote Database is Available and Unschedule/Reschedule Does Not ResolveNOTE:566622.1 - ORA-22275 when propagating >4K AQ$_JMS_TEXT_MESSAGEs from 9.2.0.8 to 10.2.0.1NOTE:727389.1 - Propagation Fails With ORA-12528NOTE:730036.1 - Overview for Troubleshooting Streams Performance IssuesNOTE:730911.1 - ORA-4063 Is Reported After Dropping Negative Prop.RulesetNOTE:731292.1 - ORA-25215 Reported On Local Propagation When Using Transformation with ANYDATA queue tablesNOTE:731539.1 - ORA-29268: HTTP client error 401 Unauthorized Error when the AQ Servlet attempts to Propagate a message via HTTPNOTE:745601.1 - ORA-23603 'STREAMS enqueue aborted due to low SGA' Error from Streams Propagation, and V$STREAMS_CAPTURE.STATE Hanging on 'Enqueuing Message'NOTE:749181.1 - How to Recover Streams After Dropping PropagationNOTE:780733.1 - Streams Propagation Tuning with Network ParametersNOTE:787367.1 - ORA-22275 reported on Propagating Messages with LOB component when propagating between 10.1 and 10.2NOTE:808136.1 - How to clear the old errors from DBA_PROPAGATION view ?NOTE:827184.1 - AQ Propagation with CLOB data types Fails with ORA-22990NOTE:827473.1 - How to alter propagation from queue_to_queue to queue_to_dblinkNOTE:839568.1 - Propagation failing with error: ORA-01536: space quota exceeded for tablespace ''NOTE:846297.1 - AQ Propagation Fails : ORA-00600[kope2upic2954] or Ora-00600[Kghsstream_copyn]NOTE:944846.1 - Streams Propagation Fails Ora-7445 [kohrsmc]

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  • SQLAuthority News – Public Training Classes In Hyderabad 12-14 May – Microsoft SQL Server 2005/2008

    - by pinaldave
    After successfully delivering many corporate trainings as well as the private training Solid Quality Mentors, India is launching the Public Training in Hyderabad for SQL Server 2008 and SharePoint 2010. This is going to be one of the most unique and one-of-a-kind events in India where Solid Quality Mentors are offering public classes. I will be leading the training on Microsoft SQL Server 2005/2008 Query Optimization & Performance Tuning. This intensive, 3-day course intends to give attendees an in-depth look at Query Optimization and Performance Tuning in SQL Server 2005 and 2008. Designed to prepare SQL Server developers and administrators for a transition into SQL Server 2005 or 2008, the course covers the best practices for a variety of essential tasks in order to maximize the performance. At the end of the course, there would be daily discussions about your real-world problems and find appropriate solutions. Note: Scroll down for course fees, discount, dates and location. Do not forget to take advantage of Discount code ‘SQLAuthority‘. The training premises are very well-equipped as they will be having 1:1 computers. Every participant will be provided with printed course materials. I will pick up your entire lunch tab and we will have lots of SQL talk together. The best participant will receive a special gift at the end of the course. Even though the quality of the material to be delivered together with the course will be of extremely high standard, the course fees are set at a very moderate rate. The fee for the course is INR 14,000/person for the whole 3-day convention. At the rate of 1 USD = 44 INR, this fee converts to less than USD 300. At this rate, it is totally possible to fly from anywhere from the world to India and take the training and still save handsome pocket money. It would be even better if you register using the discount code “SQLAuthority“, for you will instantly get an INR 3000 discount, reducing the total cost of the training to INR 11,000/person for whole 3 days course. This is a onetime offer and will not be available in the future. Please note that there will be a 10.3% service tax on course fees. To register, either send an email to [email protected] or call +91 95940 43399. Feel free to drop me an email at [email protected] for any additional information and clarification. Training Date and Time: May 12-14, 2010 10 AM- 6 PM. Training Venue: Abridge Solutions, #90/B/C/3/1, Ganesh GHR & MSY Plaza, Vittalrao Nagar, Near Image Hospital, Madhapur, Hyderabad – 500 081. The details of the course is as listed below. Day 1 : Strengthen the basics along with SQL Server 2005/2008 New Features Module 01: Subqueries, Ranking Functions, Joins and Set Operations Module 02: Table Expressions Module 03: TOP and APPLY Module 04: SQL Server 2008 Enhancements Day 2: Query Optimization & Performance Tuning 1 Module 05: Logical Query Processing Module 06: Query Tuning Module 07:  Introduction to the Query Processor Module 08:  Review of common query coding which causes poor performance Day 3: Query Optimization & Performance Tuning 2 Module 09:  SQL Server Indexing and index maintenance Module 10:  Plan Guides, query hints, UDFs, and Computed Columns Module 11:  Understanding SQL Server Execution Plans Module 12: Real World Index and Optimization Tips Download the complete PDF brochure. We are also going to have SharePoint 2010 training by Joy Rathnayake on 10-11 May. All the details for discount applies to the same as well. Reference : Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, SQL Training, SQLAuthority News, T SQL, Technology

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  • Slow wifi on Ubuntu 12.04 wifi driver ath9k

    - by lunar
    For the last couple of days my wifi connection is extremely slow. I am pretty sure that it is caused by the driver. Can this be improved? lo no wireless extensions. wlan0 IEEE 802.11bgn ESSID:"MyWiFi" Mode:Managed Frequency:2.437 GHz Access Point: 00:18:68:FE:7B:C7 Bit Rate=58.5 Mb/s Tx-Power=15 dBm Retry long limit:7 RTS thr:off Fragment thr:off Power Management:off Link Quality=48/70 Signal level=-62 dBm Rx invalid nwid:0 Rx invalid crypt:0 Rx invalid frag:0 Tx excessive retries:0 Invalid misc:6960 Missed beacon:0 eth0 no wireless extensions. sudo lshw -class network *-network description: Wireless interface product: AR9285 Wireless Network Adapter (PCI-Express) vendor: Atheros Communications Inc. physical id: 0 bus info: pci@0000:03:00.0 logical name: wlan0 version: 01 serial: 74:f0:6d:34:c2:4e width: 64 bits clock: 33MHz capabilities: pm msi pciexpress bus_master cap_list ethernet physical wireless configuration: broadcast=yes driver=ath9k driverversion=3.2.0-31-generic-pae firmware=N/A ip=192.168.1.2 latency=0 link=yes multicast=yes wireless=IEEE 802.11bgn resources: irq:17 memory:d7400000-d740ffff *-network description: Ethernet interface product: AR8131 Gigabit Ethernet vendor: Atheros Communications Inc. physical id: 0 bus info: pci@0000:06:00.0 logical name: eth0 version: c0 serial: 48:4b:38:78:f6:ae capacity: 1Gbit/s width: 64 bits clock: 33MHz capabilities: pm msi pciexpress vpd bus_master cap_list ethernet physical tp 10bt 10bt-fd 100bt 100bt-fd 1000bt-fd autonegotiation configuration: autonegotiation=on broadcast=yes driver=atl1c driverversion=1.0.1.0-NAPI firmware=N/A latency=0 link=no multicast=yes port=twisted pair resources: irq:51 memory:d3800000-d383ffff ioport:8000(size=128) lsusb Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub Bus 002 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub Bus 003 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub Bus 004 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub Bus 001 Device 002: ID 8087:0020 Intel Corp. Integrated Rate Matching Hub Bus 002 Device 002: ID 8087:0020 Intel Corp. Integrated Rate Matching Hub Bus 001 Device 003: ID 04f2:b1bb Chicony Electronics Co., Ltd Bus 001 Device 004: ID 0b05:1788 ASUSTek Computer, Inc. lspci 00:00.0 Host bridge: Intel Corporation Core Processor DRAM Controller (rev 18) 00:01.0 PCI bridge: Intel Corporation Core Processor PCI Express x16 Root Port (rev 18) 00:02.0 VGA compatible controller: Intel Corporation Core Processor Integrated Graphics Controller (rev 18) 00:16.0 Communication controller: Intel Corporation 5 Series/3400 Series Chipset HECI Controller (rev 06) 00:1a.0 USB controller: Intel Corporation 5 Series/3400 Series Chipset USB2 Enhanced Host Controller (rev 06) 00:1b.0 Audio device: Intel Corporation 5 Series/3400 Series Chipset High Definition Audio (rev 06) 00:1c.0 PCI bridge: Intel Corporation 5 Series/3400 Series Chipset PCI Express Root Port 1 (rev 06) 00:1c.1 PCI bridge: Intel Corporation 5 Series/3400 Series Chipset PCI Express Root Port 2 (rev 06) 00:1c.3 PCI bridge: Intel Corporation 5 Series/3400 Series Chipset PCI Express Root Port 4 (rev 06) 00:1c.4 PCI bridge: Intel Corporation 5 Series/3400 Series Chipset PCI Express Root Port 5 (rev 06) 00:1c.5 PCI bridge: Intel Corporation 5 Series/3400 Series Chipset PCI Express Root Port 6 (rev 06) 00:1d.0 USB controller: Intel Corporation 5 Series/3400 Series Chipset USB2 Enhanced Host Controller (rev 06) 00:1e.0 PCI bridge: Intel Corporation 82801 Mobile PCI Bridge (rev a6) 00:1f.0 ISA bridge: Intel Corporation Mobile 5 Series Chipset LPC Interface Controller (rev 06) 00:1f.2 SATA controller: Intel Corporation 5 Series/3400 Series Chipset 4 port SATA AHCI Controller (rev 06) 00:1f.6 Signal processing controller: Intel Corporation 5 Series/3400 Series Chipset Thermal Subsystem (rev 06) 01:00.0 VGA compatible controller: NVIDIA Corporation GF108 [GeForce GT 425M] (rev a1) 03:00.0 Network controller: Atheros Communications Inc. AR9285 Wireless Network Adapter (PCI-Express) (rev 01) 04:00.0 USB controller: Fresco Logic Device 1400 (rev 01) 06:00.0 Ethernet controller: Atheros Communications Inc. AR8131 Gigabit Ethernet (rev c0) ff:00.0 Host bridge: Intel Corporation Core Processor QuickPath Architecture Generic Non-core Registers (rev 05) ff:00.1 Host bridge: Intel Corporation Core Processor QuickPath Architecture System Address Decoder (rev 05) ff:02.0 Host bridge: Intel Corporation Core Processor QPI Link 0 (rev 05) ff:02.1 Host bridge: Intel Corporation Core Processor QPI Physical 0 (rev 05) ff:02.2 Host bridge: Intel Corporation Core Processor Reserved (rev 05) ff:02.3 Host bridge: Intel Corporation Core Processor Reserved (rev 05) rfkill list all 0: hci0: Bluetooth Soft blocked: yes Hard blocked: no 1: phy0: Wireless LAN Soft blocked: no Hard blocked: no

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  • Determining Maximum Txpower a WiFi Card Supports?

    - by BigGenius
    I have a Atheros R9285 wifi card. How can i determine , what is max. Txpower it can support? biggenius@hackbook:~$ iwconfig lo no wireless extensions. wlan0 IEEE 802.11abgn ESSID:"Default" Mode:Managed Frequency:2.437 GHz Access Point: 00:08:5C:9D:4F:40 Bit Rate=2 Mb/s Tx-Power=35 dBm Retry long limit:7 RTS thr:off Fragment thr:off Power Management:on Link Quality=24/70 Signal level=-86 dBm Rx invalid nwid:0 Rx invalid crypt:0 Rx invalid frag:0 Tx excessive retries:140 Invalid misc:247 Missed beacon:0 eth0 no wireless extensions. biggenius@hackbook:~$ iw phy0 info Wiphy phy0 Band 1: Capabilities: 0x11ce HT20/HT40 SM Power Save disabled RX HT40 SGI TX STBC RX STBC 1-stream Max AMSDU length: 3839 bytes DSSS/CCK HT40 Maximum RX AMPDU length 65535 bytes (exponent: 0x003) Minimum RX AMPDU time spacing: 8 usec (0x06) HT TX/RX MCS rate indexes supported: 0-7 Frequencies: * 2412 MHz [1] (35.0 dBm) * 2417 MHz [2] (35.0 dBm) * 2422 MHz [3] (35.0 dBm) * 2427 MHz [4] (35.0 dBm) * 2432 MHz [5] (35.0 dBm) * 2437 MHz [6] (35.0 dBm) * 2442 MHz [7] (35.0 dBm) * 2447 MHz [8] (35.0 dBm) * 2452 MHz [9] (35.0 dBm) * 2457 MHz [10] (35.0 dBm) * 2462 MHz [11] (35.0 dBm) * 2467 MHz [12] (35.0 dBm) * 2472 MHz [13] (35.0 dBm) * 2484 MHz [14] (35.0 dBm) Bitrates (non-HT): * 1.0 Mbps * 2.0 Mbps (short preamble supported) * 5.5 Mbps (short preamble supported) * 11.0 Mbps (short preamble supported) * 6.0 Mbps * 9.0 Mbps * 12.0 Mbps * 18.0 Mbps * 24.0 Mbps * 36.0 Mbps * 48.0 Mbps * 54.0 Mbps Band 2: Capabilities: 0x11ce HT20/HT40 SM Power Save disabled RX HT40 SGI TX STBC RX STBC 1-stream Max AMSDU length: 3839 bytes DSSS/CCK HT40 Maximum RX AMPDU length 65535 bytes (exponent: 0x003) Minimum RX AMPDU time spacing: 8 usec (0x06) HT TX/RX MCS rate indexes supported: 0-7 Frequencies: * 5180 MHz [36] (35.0 dBm) * 5200 MHz [40] (35.0 dBm) * 5220 MHz [44] (35.0 dBm) * 5240 MHz [48] (35.0 dBm) * 5260 MHz [52] (35.0 dBm) (passive scanning, no IBSS, radar detection) * 5280 MHz [56] (35.0 dBm) (passive scanning, no IBSS, radar detection) * 5300 MHz [60] (35.0 dBm) (passive scanning, no IBSS, radar detection) * 5320 MHz [64] (35.0 dBm) (passive scanning, no IBSS, radar detection) * 5500 MHz [100] (35.0 dBm) (passive scanning, no IBSS, radar detection) * 5520 MHz [104] (35.0 dBm) (passive scanning, no IBSS, radar detection) * 5540 MHz [108] (35.0 dBm) (passive scanning, no IBSS, radar detection) * 5560 MHz [112] (35.0 dBm) (passive scanning, no IBSS, radar detection) * 5580 MHz [116] (35.0 dBm) (passive scanning, no IBSS, radar detection) * 5600 MHz [120] (35.0 dBm) (passive scanning, no IBSS, radar detection) * 5620 MHz [124] (35.0 dBm) (passive scanning, no IBSS, radar detection) * 5640 MHz [128] (35.0 dBm) (passive scanning, no IBSS, radar detection) * 5660 MHz [132] (35.0 dBm) (passive scanning, no IBSS, radar detection) * 5680 MHz [136] (35.0 dBm) (passive scanning, no IBSS, radar detection) * 5700 MHz [140] (35.0 dBm) (passive scanning, no IBSS, radar detection) * 5745 MHz [149] (35.0 dBm) * 5765 MHz [153] (35.0 dBm) * 5785 MHz [157] (35.0 dBm) * 5805 MHz [161] (35.0 dBm) * 5825 MHz [165] (35.0 dBm) Bitrates (non-HT): * 6.0 Mbps * 9.0 Mbps * 12.0 Mbps * 18.0 Mbps * 24.0 Mbps * 36.0 Mbps * 48.0 Mbps * 54.0 Mbps max # scan SSIDs: 4 max scan IEs length: 2257 bytes Coverage class: 0 (up to 0m) Supported Ciphers: * WEP40 (00-0f-ac:1) * WEP104 (00-0f-ac:5) * TKIP (00-0f-ac:2) * CCMP (00-0f-ac:4) * CMAC (00-0f-ac:6) Available Antennas: TX 0x1 RX 0x3 Configured Antennas: TX 0x1 RX 0x3 Supported interface modes: * IBSS * managed * AP * AP/VLAN * WDS * monitor * mesh point * P2P-client * P2P-GO software interface modes (can always be added): * AP/VLAN * monitor valid interface combinations: * #{ managed, WDS, P2P-client } <= 2048, #{ AP, mesh point, P2P-GO } <= 8, total <= 2048, #channels <= 1 Supported commands: * new_interface * set_interface * new_key * new_beacon * new_station * new_mpath * set_mesh_params * set_bss * authenticate * associate * deauthenticate * disassociate * join_ibss * join_mesh * remain_on_channel * set_tx_bitrate_mask * action * frame_wait_cancel * set_wiphy_netns * set_channel * set_wds_peer * Unknown command (82) * Unknown command (81) * Unknown command (84) * Unknown command (87) * Unknown command (85) * testmode * connect * disconnect Supported TX frame types: * IBSS: 0x0000 0x0010 0x0020 0x0030 0x0040 0x0050 0x0060 0x0070 0x0080 0x0090 0x00a0 0x00b0 0x00c0 0x00d0 0x00e0 0x00f0 * managed: 0x0000 0x0010 0x0020 0x0030 0x0040 0x0050 0x0060 0x0070 0x0080 0x0090 0x00a0 0x00b0 0x00c0 0x00d0 0x00e0 0x00f0 * AP: 0x0000 0x0010 0x0020 0x0030 0x0040 0x0050 0x0060 0x0070 0x0080 0x0090 0x00a0 0x00b0 0x00c0 0x00d0 0x00e0 0x00f0 * AP/VLAN: 0x0000 0x0010 0x0020 0x0030 0x0040 0x0050 0x0060 0x0070 0x0080 0x0090 0x00a0 0x00b0 0x00c0 0x00d0 0x00e0 0x00f0 * mesh point: 0x0000 0x0010 0x0020 0x0030 0x0040 0x0050 0x0060 0x0070 0x0080 0x0090 0x00a0 0x00b0 0x00c0 0x00d0 0x00e0 0x00f0 * P2P-client: 0x0000 0x0010 0x0020 0x0030 0x0040 0x0050 0x0060 0x0070 0x0080 0x0090 0x00a0 0x00b0 0x00c0 0x00d0 0x00e0 0x00f0 * P2P-GO: 0x0000 0x0010 0x0020 0x0030 0x0040 0x0050 0x0060 0x0070 0x0080 0x0090 0x00a0 0x00b0 0x00c0 0x00d0 0x00e0 0x00f0 Supported RX frame types: * IBSS: 0x00d0 * managed: 0x0040 0x00d0 * AP: 0x0000 0x0020 0x0040 0x00a0 0x00b0 0x00c0 0x00d0 * AP/VLAN: 0x0000 0x0020 0x0040 0x00a0 0x00b0 0x00c0 0x00d0 * mesh point: 0x00b0 0x00c0 0x00d0 * P2P-client: 0x0040 0x00d0 * P2P-GO: 0x0000 0x0020 0x0040 0x00a0 0x00b0 0x00c0 0x00d0 Device supports RSN-IBSS.

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  • Knowledge Management Feedback

    - by Robert Schweighardt
    Did you know that you can provide feedback on Knowledge Management (KM) articles? It's nice to read a technical article that is well-written, the grammar and spelling are correct, the information is up to date, concise, to the point, easy to understand and it flows from one paragraph to another.  And though we always strive for a well-written article, it doesn't always come out that way. Knowledge Management articles are written by Oracle Support Engineers and we welcome your feedback.  Providing feedback helps to improve Oracle's Knowledge Base.  If you're reading a KM article and you have a comment, please let us know about it.  Maybe it's just to fix a spelling or grammatical error.  Maybe there's a broken link that needs to be fixed.  Maybe it's a suggestion to provide additional information.  Maybe the article contains incorrect information.  Maybe some information in the article is outdated.  Maybe something is not clear in the article.  Whatever it is, we want to hear about it.  We value your input! When you provide feedback it goes directly to the owner of the article.  The owner carefully reviews the comment and decides whether or not to implement it.  Most comments are implemented and we strive to implement them within a week!  For those comments that are not implemented, there is normally a good reason.  It may not be feasible to implement the suggestion or the suggestion may not be correct.  We don't take the decision lightly! So how do you provide feedback? Providing feedback on a KM article depends on whether you're a customer or an Oracle Employee. Customer 1. In the upper right hand corner of the article, click on the little +/- Rate this document icon: Note: The grayed out Comments (0) link will only show a number when there are open comments that are still being evaluated. 2. In the Article Rating window, complete as many of the following optional fields as you like and then click the Send Rating button: Rate the article as Excellent, Good or Poor Specify whether the article helped you or not Specify the ease of finding the article Provide whatever comments you have Employee The interface for Oracle Employees is a little bit different, there are more options. 1. The +/- Rate this document icon is also available to employees and is identical to what the customers have.  Please see Customer section above. 2. The Show document comments link shows all comments that have ever been submitted for the article 3. Employees have an additional way to submit a comment.  Click on the little + Add Comment icon: 4. Fill out the Add Comment fields and click the Add Comment button: We look forward to your feedback!

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  • Organization &amp; Architecture UNISA Studies &ndash; Chap 6

    - by MarkPearl
    Learning Outcomes Discuss the physical characteristics of magnetic disks Describe how data is organized and accessed on a magnetic disk Discuss the parameters that play a role in the performance of magnetic disks Describe different optical memory devices Magnetic Disk The way data is stored on and retried from magnetic disks Data is recorded on and later retrieved form the disk via a conducting coil named the head (in many systems there are two heads) The writ mechanism exploits the fact that electricity flowing through a coil produces a magnetic field. Electric pulses are sent to the write head, and the resulting magnetic patterns are recorded on the surface below with different patterns for positive and negative currents The physical characteristics of a magnetic disk   Summarize from book   The factors that play a role in the performance of a disk Seek time – the time it takes to position the head at the track Rotational delay / latency – the time it takes for the beginning of the sector to reach the head Access time – the sum of the seek time and rotational delay Transfer time – the time it takes to transfer data RAID The rate of improvement in secondary storage performance has been considerably less than the rate for processors and main memory. Thus secondary storage has become a bit of a bottleneck. RAID works on the concept that if one disk can be pushed so far, additional gains in performance are to be had by using multiple parallel components. Points to note about RAID… RAID is a set of physical disk drives viewed by the operating system as a single logical drive Data is distributed across the physical drives of an array in a scheme known as striping Redundant disk capacity is used to store parity information, which guarantees data recoverability in case of a disk failure (not supported by RAID 0 or RAID 1) Interesting to note that the increase in the number of drives, increases the probability of failure. To compensate for this decreased reliability RAID makes use of stored parity information that enables the recovery of data lost due to a disk failure.   The RAID scheme consists of 7 levels…   Category Level Description Disks Required Data Availability Large I/O Data Transfer Capacity Small I/O Request Rate Striping 0 Non Redundant N Lower than single disk Very high Very high for both read and write Mirroring 1 Mirrored 2N Higher than RAID 2 – 5 but lower than RAID 6 Higher than single disk Up to twice that of a signle disk for read Parallel Access 2 Redundant via Hamming Code N + m Much higher than single disk Highest of all listed alternatives Approximately twice that of a single disk Parallel Access 3 Bit interleaved parity N + 1 Much higher than single disk Highest of all listed alternatives Approximately twice that of a single disk Independent Access 4 Block interleaved parity N + 1 Much higher than single disk Similar to RAID 0 for read, significantly lower than single disk for write Similar to RAID 0 for read, significantly lower than single disk for write Independent Access 5 Block interleaved parity N + 1 Much higher than single disk Similar to RAID 0 for read, lower than single disk for write Similar to RAID 0 for read, generally  lower than single disk for write Independent Access 6 Block interleaved parity N + 2 Highest of all listed alternatives Similar to RAID 0 for read; lower than RAID 5 for write Similar to RAID 0 for read, significantly lower than RAID 5  for write   Read page 215 – 221 for detailed explanation on RAID levels Optical Memory There are a variety of optical-disk systems available. Read through the table on page 222 – 223 Some of the devices include… CD CD-ROM CD-R CD-RW DVD DVD-R DVD-RW Blue-Ray DVD Magnetic Tape Most modern systems use serial recording – data is lade out as a sequence of bits along each track. The typical recording used in serial is referred to as serpentine recording. In this technique when data is being recorded, the first set of bits is recorded along the whole length of the tape. When the end of the tape is reached the heads are repostioned to record a new track, and the tape is again recorded on its whole length, this time in the opposite direction. That process continued back and forth until the tape is full. To increase speed, the read-write head is capable of reading and writing a number of adjacent tracks simultaneously. Data is still recorded serially along individual tracks, but blocks in sequence are stored on adjacent tracks as suggested. A tape drive is a sequential access device. Magnetic tape was the first kind of secondary memory. It is still widely used as the lowest-cost, slowest speed member of the memory hierarchy.

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