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• Automatic Storage Management (ASM)

  - by jean-marc.gaudron(at)oracle.com

  Master Note for Automatic Storage Management (ASM) (Doc ID 1187723.1)This Master Note is intended to provide an index and references to the most frequently used My Oracle Support Notes with respect to Oracle Automatic Storage Management (ASM) environments. This Master Note is subdivided into categories to allow for easy access and reference to notes that are applicable to your area of interest. This includes the following categories: Automatic Storage Management (ASM) Concepts and Overview Automatic Storage Management (ASM) Installation Automatic Storage Management (ASM) Configuration Automatic Storage Management (ASM) Administration Automatic Storage Management (ASM) Migration and Upgrade Automatic Storage Management (ASM) Monitoring Automatic Storage Management (ASM) Troubleshooting and Debugging Automatic Storage Management (ASM) Best Practices Automatic Storage Management (ASM) Versions and Patches ASMLIB Database Machine, Exadata Storage Server and RAC Documentation Using My Oracle Support Effectively

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• ORA-7445 Troubleshooting

  - by [email protected]

      QUICKLINK: Note 153788.1 ORA-600/ORA-7445 Lookup tool Note 1082674.1 : A Video To Demonstrate The Usage Of The ORA-600/ORA-7445 Lookup Tool [Video]   Have you observed an ORA-07445 error reported in your alert log? While the ORA-600 error is "captured" as a handled exception in the Oracle source code, the ORA-7445 is an unhandled exception error due to an OS exception which should result in the creation of a core file.  An ORA-7445 is a generic error, and can occur from anywhere in the Oracle code. The precise location of the error is identified by the core file and/or trace file it produces.  Looking for the best way to diagnose? Whenever an ORA-7445 error is raised a core file is generated.  There may be a trace file generated with the error as well.   Prior to 11g, the core files are located in the CORE_DUMP_DEST directory.   Starting with 11g, there is a new advanced fault diagnosability infrastructure to manage trace data.  Diagnostic files are written into a root directory for all diagnostic data called the ADR home.   Core files at 11g will go to the ADR HOME/cdump directory.   For more information on the Oracle 11g Diagnosability feature see Note 453125.1 11g Diagnosability Frequently Asked Questions Note 443529.1 11g Quick Steps to Package and Send Critical Error Diagnostic Information to Support[Video]   NOTE:  While the core file is captured in the Diagnosability infrastructure, the file may not be included with a diagnostic package.1.  Check the Alert LogThe alert log may indicate additional errors or other internal errors at the time of the problem.   In some cases, the ORA-7445 error will occur along with ORA-600, ORA-3113, ORA-4030 errors.  The ORA-7445 error can be side effects of the other problems and you should review the first error and associated core file or trace file and work down the list of errors.   Note 1020463.6 DIAGNOSING ORA-3113 ERRORS Note 1812.1 TECH:  Getting a Stack Trace from a CORE file Note 414966.1 RDA Documentation Index   If the ORA-7445 errors are not associated with other error conditions, ensure the trace data is not truncated. If you see a message at the end of the file   "MAX DUMP FILE SIZE EXCEEDED"   the MAX_DUMP_FILE_SIZE parameter is not setup high enough or to 'unlimited'. There could be vital diagnostic information missing in the file and discovering the root issue may be very difficult.  Set the MAX_DUMP_FILE_SIZE appropriately and regenerate the error for complete trace information. For pointers on deeper analysis of these errors see   Note 390293.1 Introduction to 600/7445 Internal Error Analysis Note 211909.1 Customer Introduction to ORA-7445 Errors 2.  Search 600/7445 Lookup Tool Visit My Oracle Support to access the ORA-00600 Lookup tool (Note 153788.1). The ORA-600/ORA-7445 Lookup tool may lead you to applicable content in My Oracle Support on the problem and can be used to investigate the problem with argument data from the error message or you can pull out key stack pointers from the associated trace file to match up against known bugs.3.  "Fine tune" searches in Knowledge Base As the ORA-7445 error indicates an unhandled exception in the Oracle source code, your search in the Oracle Knowledge Base will need to focus on the stack data from the core file or the trace file. Keep in mind that searches on generic argument data will bring back a large result set.  The more you can learn about the environment and code leading to the errors, the easier it will be to narrow the hit list to match your problem. Note 153788.1 ORA-600/ORA-7445 TroubleshooterNote 1082674.1 A Video To Demonstrate The Usage Of The ORA-600/ORA-7445 Lookup Tool [Video] NOTE:  If no trace file is captured, see Note 1812.1 TECH:  Getting a Stack Trace from a CORE file.  Core files are managed through 11g Diagnosability, but are not packaged with other diagnostic data automatically.  The core files can be quite large, but may be useful during analysis within Oracle Support.4.  If assistance is required from Oracle Should it become necessary to get assistance from Oracle Support on an ORA-7445 problem, please provide at a minimum, the Alert log  Associated tracefile(s) or incident package at 11g Patch level  information Core file(s)  Information about changes in configuration and/or application prior to  issues  If error is reproducible, a self-contained reproducible testcase: Note.232963.1 How to Build a Testcase for Oracle Data Server Support to Reproduce ORA-600 and ORA-7445 Errors RDA report or Oracle Configuration Manager information Oracle Configuration Manager Quick Start Guide Note 548815.1 My Oracle Support Configuration Management FAQ Note 414966.1 RDA Documentation Index ***For reference to the content in this blog, refer to Note.1092832.1 Master Note for Diagnosing ORA-600

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• Eee PC brighness contol with 12.04 release

  - by Terry

  is there a solution to the low screen brightness issue with the Eee PC and release 12.04? When I use the brightness control, the screen goes through three adjustment cycles of dark to semi bright, but never gets to bright. As you index the control up, brightness increases, then suddenly cuts back to dark. use the brightness button to further increase the brightness and the same cycle happens. As though there are three distinct brightness events, each one setting back to low level. Under no circumstances other than initial boot up can you get to a bright screen. I just finished installing 12.04 on two Acer (Gateway netbooks) with no brightness issue. Just on the Eee PC

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• How to Use RDA to Generate WLS Thread Dumps At Specified Intervals?

  - by Daniel Mortimer

  Introduction There are many ways to generate a thread dump of a WebLogic Managed Server. For example, take a look at: Taking Thread Dumps - [an excellent blog post on the Middleware Magic site]or  Different ways to take thread dumps in WebLogic Server (Document 1098691.1) There is another method - use Remote Diagnostic Agent! The solution described below is not documented, but it is relatively straightforward to execute. One advantage of using RDA to collect the thread dumps is RDA will also collect configuration, log files, network, system, performance information at the same time. Instructions 1. Not familiar with Remote Diagnostic Agent? Take a look at my previous blog "Resolve SRs Faster Using RDA - Find the Right Profile" 2. Choose a profile, which includes the WebLogic Server data collection modules (for example the profile "WebLogicServer"). At RDA setup time you should see the prompt below: ------------------------------------------------------------------------------- S301WLS: Collects Oracle WebLogic Server Information ------------------------------------------------------------------------------- Enter the location of the directory where the domains to analyze are located (For example in UNIX, <BEA Home>/user_projects/domains or <Middleware Home>/user_projects/domains) Hit 'Return' to accept the default (/oracle/11AS/Middleware/user_projects/domains) > For a successful WLS connection, ensure that the domain Admin Server is up and running. Data Collection Type:   1  Collect for a single server (offline mode)   2  Collect for a single server (using WLS connection)   3  Collect for multiple servers (using WLS connection) Enter the item number Hit 'Return' to accept the default (1) > 2 Choose option 2 or 3. Note: Collect for a single server or multiple servers using WLS connection means that RDA will attempt to connect to execute online WLST commands against the targeted server(s). The thread dumps are collected using the WLST function - "threadDumps()". If WLST cannot connect to the managed server, RDA will proceed to collect other data and ignore the request to collect thread dumps. If in the final output you see no Thread Dump menu item, then it's likely that the managed server is in a state which prevents new connections to it. If faced with this scenario, you would have to employ alternative methods for collecting thread dumps. 3. The RDA setup will create a setup.cfg file in the RDA_HOME directory. Open this file in an editor. You will find the following parameters which govern the number of thread dumps and thread dump interval. #N.Number of thread dumps to capture WREQ_THREAD_DUMP=10 #N.Thread dump interval WREQ_THREAD_DUMP_INTERVAL=5000 The example lines above show the default settings. In other words, RDA will collect 10 thread dumps at 5000 millisecond (5 second) intervals. You may want to change this to something like: #N.Number of thread dumps to capture WREQ_THREAD_DUMP=10 #N.Thread dump interval WREQ_THREAD_DUMP_INTERVAL=30000 However, bear in mind, that such change will increase the total amount of time it takes for RDA to complete its run. 4. Once you are happy with the setup.cfg, run RDA. RDA will collect, render, generate and package all files in the output directory. 5. For ease of viewing, open up the RDA Start html file - "xxxx__start.htm". The thread dumps can be found under the WLST Collections for the target managed server(s). See screenshots belowScreenshot 1:RDA Start Page - Main Index Screenshot 2: Managed Server Sub Index Screenshot 3: WLST Collections Screenshot 4: Thread Dump Page - List of dump file links Screenshot 5: Thread Dump Dat File Link Additional Comment: A) You can view the thread dump files within the RDA Start Page framework, but most likely you will want to download the dat files for in-depth analysis via thread dump analysis tools such as: Thread Dump Analyzer -  Samurai - a GUI based tail , thread dump analysis tool If you are new to thread dump analysis - take a look at this recorded Support Advisor Webcast  Oracle WebLogic Server: Diagnosing Performance Issues through Java Thread Dumps[Slidedeck from webcast in PDF format]B) I have logged a couple of enhancement requests for the RDA Development Team to consider: Add timestamp to dump file links, dat filename and at the top of the body of the dat file Package the individual thread dumps in a zip so all dump files can be conveniently downloaded in one go.

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• Reverse horizontal and vertical for a HTML table

  - by porton

  There is a two-dimensional array describing a HTML table. Each element of the array consists of: the cell content rowspan colspan Every row of this two dimensional array corresponds to <td> cells of a <tr> of the table which my software should generate. I need to "reverse" the array (interchange vertical and horizontal direction). Insofar I considered algorithm based on this idea: make a rectangular matrix of the size of the table and store in every element of this matrix the corresponding index of the element of the above mentioned array. (Note that two elements of the matrix may be identical due rowspan/colspan.) Then I could use this matrix to calculate rowspan/colspan for the inverted table. But this idea seems bad for me. Any other algorithms? Note that I program in PHP.

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• 3DS Max exporting too many vertexes for model

  - by Juan Pablo

  I have a sample model of a cube and a buddha downloaded from internet in 3ds format which I can load correctly into my program and view them without problem, but wanted to try and create my own model. I created a simple box mesh in 3ds max, and exported it as .3ds (Converted to mesh - export as .3ds) When inspecting the .3ds file with a hex viewer, I was expecting to see 8 vertexes and 12 faces declared (as the model I downloaded from internet). But what i found was that it listed 26 vertexes, and 12 faces! And when I try to load that file with my .3ds viewer, my parser isn't detecting the face block (0x4120), which is strange because it worked for other objects downloaded from internet. Do I have to set any special property in order to export a 3ds file with minimum vertexes and a vertex-index list?

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• Join us! Oracle Manufacturing Industries Forum, Chicago Thurs. Nov.14'13

  - by Stephen Slade

  The 6th Annual Oracle Manufacturing Industries Forum will take place in Chicago, Thurs, Nov.14 '13. Executives from successful global manufacturing companies will address key themes including: Value Chain Transformation, Owning the Customer Service Experience, Sales and Operations Planning in a Global Enterprise Supply Chain, and Modernizing the Manufacturing Enterprise. Join us for what we expect to be one of the industry's most informative and provocative executive events of the year. Event Objectives: Create an environment where executives can interact with their peers to discuss current issues Brainstorm and discuss how attendees can use technology to transform their organizations Share best practices and learn through the experiences of industry peers Where: Westin Chicago River North,  320 North Dearborn St,  Chicago, IL 60654 Evite: http://www.oracle.com/us/dm/229048-nafm13049989mpp074-se-2021171.html Register:   http://eventreg.oracle.com/profile/web/index.cfm?PKWebId=0x25005591a&source=evite Partner Sponsors Include: CSS, Fujitsu, Inspirage, Hitachi Consulting, Lucidity and Rolta Register Now!

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• Traffic fall after a server problem

  - by Sébastien

  I have a website from which I analyse the traffic with Google analytics. Day after day the traffic (mainly from Google SE) incresed until I get a problem with my server. For one day the server has been offline and after that I have no longer had as much users as I had before. Now it's like the site is no more referenced on Google index (but when I type "site:mysite.com", I still have all the results). Do you know if this is a normal behaviour and if the traffic will come back as before (the server has had problems two days ago) ?

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• Which tools you use to make gtk themes?

  - by tutuca

  I'm trying to make a new gtk theme using the murrine engine, using Humanity (default in ubuntu 9.10) as a template. You can grab the code in http://github.com/tutuca/themes However, I found cumbersome the process of creating a new theme with it. There is no central starting point. The documentation of both, the engine options (gtkrc's and stuff), and general theming practices (the format of the index.theme files, folders, bla bla) is scarce, How to's and tutorials are often old or subject to lots of opinionated debate and results confusing (to me, having a web developer background, at least :-). So... I wanted to ask to the fellows gtk themers and artist out there: Which tools you use to create a new theme, and how does your average workflow looks like?

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• "'/usr/share/app-install/desktop/software-center.menu': Not a directory" error when trying to reinstall the software center

  - by EnTer

  I was having some problem with Software center. So tried to reinstall it. But While removing it give me an error. (Reading database ... 150986 files and directories currently installed.) Removing software-center ... dpkg: error processing software-center (--remove): unable to securely remove '/usr/share/app-install/desktop/software-center.menu': Not a directory Processing triggers for man-db ... Processing triggers for hicolor-icon-theme ... Processing triggers for desktop-file-utils ... Processing triggers for gnome-menus ... Processing triggers for bamfdaemon ... Rebuilding /usr/share/applications/bamf.index... Errors were encountered while processing: software-center E: Sub-process /usr/bin/dpkg returned an error code (1) Now The same problem is repeating if I use apt-get to install or upgrade my ubuntu. I cant install any software and Software-Center too.. PLZ help

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• install Cirrus Logic cs46xx (audio card) drivers

  - by Aikanáro

  I have two sounds cards, one is the on-board (it's VIA) the other is Cirrus Logic cs46xx. This is what lspci shows me: 04:04.0 Multimedia audio controller: Cirrus Logic CS 4614/22/24/30 [CrystalClear SoundFusion Audio Accelerator] (rev 01) It only show the cirrus logic, cause I disable the VIA card through BIOS. This page: http://es.driverscollection.com/?file_id=13152 gives me instructions to install it, but I can follow them because the folders indicates in the page do not matches with the ones that I see in my system. The alsa page: http://alsa-project.org/main/index.php/Matrix:Module-cs46xx, also give me instructions, but I don't understand it. For example, they say: type in a terminal: ./configure but don't say in what directory. I think that isn't instructions for begginers... Right now I can't heard anything. I decide to disable the VIA audio card, cause I've read they don't get along with linux, although i use the integrate VIA video card. I have ubuntu 11.10

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• How do I get brightness controls working properly on an Eee PC 1001P?

  - by Terry

  Is there a solution to the low screen brightness issue with the Eee PC 1001P and release 12.04? When I use the brightness control, the screen goes through three adjustment cycles of dark to semi bright, but never gets to bright. As you index the control up, brightness increases, then suddenly cuts back to dark. use the brightness button to further increase the brightness and the same cycle happens. As though there are three distinct brightness events, each one setting back to low level. Under no circumstances other than initial boot up can you get to a bright screen. I just finished installing 12.04 on two Acer (Gateway netbooks) with no brightness issue. Just on the Eee PC 1001P Eee PC model is 1001P

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• Only 192.168.0.3 can request, but anyone can request /public/file.html

  - by mattalexx

  I have the following virtual host on my development server: <VirtualHost *:80> ServerName example.com DocumentRoot /srv/web/example.com/pub <Directory /srv/web/example.com/pub> Order Deny,Allow Deny from all Allow from 192.168.0.3 </Directory> </VirtualHost> The Allow from 192.168.0.3 part is to only allow requests from my workstation machine. I want to tweak this to allow anyone to request a certain URL: http://example.com/public/file.html How do I change this to allow /public/file.html requests to get through from anyone? Note: /public/file.html doesn't actually exist as a file on the server. I redirect all incoming requests through a single index file using mod_rewrite.

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• SEO for a list of products with filters

  - by dana

  I am a wondering if there is a recommended "best practice" for a product search SEO. I know to create a dynamic sitemap file that lists links to all products in the site. However, I want to implement a a bookmark-able "advanced search". Should I let search engines index any of the results? Take the following parameters for a search on a make believe used car website: minprice (minimum price in dollars) maxprice (maximum price in dollars) make (honda, audi, volvo) model (accord, A4, S40) minyear (minimum model year) maxyear (maximum model year) minmileage (minimum mileage) maxmileage (maximum mileage) Given these parameters, there could be an infinite number of search combinations: Price Between $10,000 and $20,000 /search?minprice=10000&maxprice&20000 Audis with less than 50k miles /search?model=audi&maxmileage=50000 More than 100,000 miles and less than $5,000 /search?minmileage=100000&maxprice=5000 etc. Over time, there may be inbound links to a variety of these types of searches, yet they are all slices of the same data. Should I allow for all of these searches to be indexed?

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• Workflow with Flash Pro CS6 and FlashDevelop: Using fla and swc to store assets

  - by Arthur Wulf White

  I am using this tutorial: http://www.flashdevelop.org/wikidocs/index.php?title=AS3:FlexAndFlashCS3Workflow In the past older versions of Flash Pro I was able to complete these steps: right-click on the symbol in the Library panel, select "Linkage..." dialog, check "Export for ActionScript" and fill in the symbol name (ie. MySymbol_design or assets.MySymbol_design), do not change the base class (ie. flash.display.MovieClip). Right now, I am stuck at that part. Any hints? What I wish to do is: Use fla for the artist to store assets. Publish to swc Extract the assets in FlashDevelop by creating an instance of their class. ... How is this done in CS6? To clear things up, this is what I see when I right click a Flash symbol:

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• Speed up Banshee's indexing of files on a device

  - by Stefano Palazzo

  I've got an external hard drive with music on it, around 250 albums. To make it work nicely with Banshee, I've created an .is_audio_player file on the device, containing audio_folders=Music. Every time I plug it in, Banshee takes around two minutes to index the thing, slowly building up the library - and being unusably sluggish while doing that. Is there, per chance, any way to speed it up? Should I not mount the hard disk as a music player, but add it's contents to my library? And, if I do, won't that give me lots of annoying X symbols next to the titles, as they can't be found sometimes? What's the best way to have my library on an external HDD?

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• Error in mounting HDD

  - by Vikramjeet

  I am getting the following error whenever I mount my external HDD. It was working before and then I opted for safely removing the drive. Now its giving me following error Error mounting: mount exited with exit code 13: ntfs_mst_post_read_fixup_warn: magic: 0x43425355 size: 4096 usa_ofs: 8850 usa_count: 65535: Invalid argument Actual VCN (0x800006009000000) of index buffer is different from expected VCN (0x0). Failed to mount '/dev/sdb1': Input/output error NTFS is either inconsistent, or there is a hardware fault, or it's a SoftRAID/FakeRAID hardware. In the first case run chkdsk /f on Windows then reboot into Windows twice. The usage of the /f parameter is very important! If the device is a SoftRAID/FakeRAID then first activate it and mount a different device under the /dev/mapper/ directory, (e.g. /dev/mapper/nvidia_eahaabcc1). Please see the 'dmraid' documentation for more details.

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• Preventing indexing duplicate content by search engines

  - by umesh awasthi

  I am in process of migrating my old domain (www.oldurl.com) to new domain (www.newurl.com). Almost all the content,URL structure as well database is same except for few URL's and only difference will be in the domain name. I have made entries in the Apache's .htaccess file to set 301 redirect and currently have blocked all search engines from crawling my new domain by setting in robot.txt file. I am not sure how i will handle the duplicate content issue as when i will make the new domain go live. Should i block search engines to index/crawl my old domain? i am new to this field and not sure if this is actually any duplicate content issue or not.

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• problem with grub-efi

  - by Jesper

  I am installing ubuntu on my MacBook, following the instructions here: http://www.rodsbooks.com/ubuntu-efi/index.html Everything has gone well so far. But I have now come to number 19. The cd with GRUB2 is in the drive, but when I type 'sudo apt-get install grub-efi' it says: package grub-efi is not available, but is referred to by another package. This may mean that the package is missing, has been obsoleted, or is only available from another source However the following packages replace it: grub2-common grub-common The Grub iso I downloaded and burned was this one: http://forja.cenatic.es/frs/download.php/1381/super_grub_disk_hybrid-1.98s1.iso

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• Oracle BI and EPM Partner Blogs

  - by Mike.Hallett(at)Oracle-BI&EPM

  Below is a simple list of some of our specialist Oracle BI and EPM Partner Blogs, where there is lots of great material and discussions.   http://www.aortabi.nl/news/ Netherlands http://www.clearpeaks.com/blog/ English http://www.peakindicators.com/index.php/knowledge-base English http://www.project.eu.com/blog/ English http://www.qubix.co.uk/insights English http://www.rittmanmead.com/blog/ English https://www.endecacommunity.com/ English   If you are a specialist OPN EMEA BI and EPM Partner with hints and tips to share, and would like your Blog to be added to this list, then just let me know @ [email protected].

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• Recovery from URL structure change?

  - by Dejan Pelzel

  in July this year, we have changed the URL structure of the website from: Post: domain.com/blog/post/986/dance/heart-beats-dance-video-by-chinatsu/ Category: domain.com/blog/index/cosplay/ to Post: domain.com/dance/heart-beats-dance-video-by-chinatsu-986/ Category: domain.com/cosplay/ Everything was (supposedly) properly redirected with 301 redirects and it first seemed that the traffic returned after a couple of days, but it has now been close to 2 months and things keep going worse although Google is slowly indexing the changes. What is worrying me even more is that the Pages crawled per day from Webmaster Tools started drastically dropping a few days ago and has just reached a new low in months (from over 2000 to 700). Should I be worried or will things sort out eventually?

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• Project Euler 2: (Iron)Python

  - by Ben Griswold

  In my attempt to learn (Iron)Python out in the open, here’s my solution for Project Euler Problem 2.  As always, any feedback is welcome. # Euler 2 # http://projecteuler.net/index.php?section=problems&id=2 # Find the sum of all the even-valued terms in the # Fibonacci sequence which do not exceed four million. # Each new term in the Fibonacci sequence is generated # by adding the previous two terms. By starting with 1 # and 2, the first 10 terms will be: # 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, ... # Find the sum of all the even-valued terms in the # sequence which do not exceed four million. import time start = time.time() total = 0 previous = 0 i = 1 while i <= 4000000: if i % 2 == 0: total +=i # variable swapping removes the need for a temp variable i, previous = previous, previous + i print total print "Elapsed Time:", (time.time() - start) * 1000, "millisecs" a=raw_input('Press return to continue')

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• Retrieving model position after applying modeltransforms in XNA

  - by Glen Dekker

  For this method that the goingBeyond XNA tutorial provides, it would be really convenient if I could retrieve the new position of the model after I apply all the transforms to the mesh. I have edited the method a little for what I need. Does anyone know a way I can do this? public void DrawModel( Camera camera ) { Matrix scaleY = Matrix.CreateScale(new Vector3(1, 2, 1)); Matrix temp = Matrix.CreateScale(100f) * scaleY * rotationMatrix * translationMatrix * Matrix.CreateRotationY(MathHelper.Pi / 6) * translationMatrix2; Matrix[] modelTransforms = new Matrix[model.Bones.Count]; model.CopyAbsoluteBoneTransformsTo(modelTransforms); if (camera.getDistanceFromPlayer(position+position1) > 3000) return; foreach (ModelMesh mesh in model.Meshes) { foreach (BasicEffect effect in mesh.Effects) { effect.EnableDefaultLighting(); effect.World = modelTransforms[mesh.ParentBone.Index] * temp * worldMatrix; effect.View = camera.viewMatrix; effect.Projection = camera.projectionMatrix; } mesh.Draw(); } }

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• InnoDB Compression Improvements in MySQL 5.6

  - by Inaam Rana

  MySQL 5.6 comes with significant improvements for the compression support inside InnoDB. The enhancements that we'll talk about in this piece are also a good example of community contributions. The work on these was conceived, implemented and contributed by the engineers at Facebook. Before we plunge into the details let us familiarize ourselves with some of the key concepts surrounding InnoDB compression. In InnoDB compressed pages are fixed size. Supported sizes are 1, 2, 4, 8 and 16K. The compressed page size is specified at table creation time. InnoDB uses zlib for compression. InnoDB buffer pool will attempt to cache compressed pages like normal pages. However, whenever a page is actively used by a transaction, we'll always have the uncompressed version of the page as well i.e.: we can have a page in the buffer pool in compressed only form or in a state where we have both the compressed page and uncompressed version but we'll never have a page in uncompressed only form. On-disk we'll always only have the compressed page. When both compressed and uncompressed images are present in the buffer pool they are always kept in sync i.e.: changes are applied to both atomically. Recompression happens when changes are made to the compressed data. In order to minimize recompressions InnoDB maintains a modification log within a compressed page. This is the extra space available in the page after compression and it is used to log modifications to the compressed data thus avoiding recompressions. DELETE (and ROLLBACK of DELETE) and purge can be performed without recompressing the page. This is because the delete-mark bit and the system fields DB_TRX_ID and DB_ROLL_PTR are stored in uncompressed format on the compressed page. A record can be purged by shuffling entries in the compressed page directory. This can also be useful for updates of indexed columns, because UPDATE of a key is mapped to INSERT+DELETE+purge. A compression failure happens when we attempt to recompress a page and it does not fit in the fixed size. In such case, we first try to reorganize the page and attempt to recompress and if that fails as well then we split the page into two and recompress both pages. Now lets talk about the three major improvements that we made in MySQL 5.6.Logging of Compressed Page Images:InnoDB used to log entire compressed data on the page to the redo logs when recompression happens. This was an extra safety measure to guard against the rare case where an attempt is made to do recovery using a different zlib version from the one that was used before the crash. Because recovery is a page level operation in InnoDB we have to be sure that all recompress attempts must succeed without causing a btree page split. However, writing entire compressed data images to the redo log files not only makes the operation heavy duty but can also adversely affect flushing activity. This happens because redo space is used in a circular fashion and when we generate much more than normal redo we fill up the space much more quickly and in order to reuse the redo space we have to flush the corresponding dirty pages from the buffer pool.Starting with MySQL 5.6 a new global configuration parameter innodb_log_compressed_pages. The default value is true which is same as the current behavior. If you are sure that you are not going to attempt to recover from a crash using a different version of zlib then you should set this parameter to false. This is a dynamic parameter.Compression Level:You can now set the compression level that zlib should choose to compress the data. The global parameter is innodb_compression_level - the default value is 6 (the zlib default) and allowed values are 1 to 9. Again the parameter is dynamic i.e.: you can change it on the fly.Dynamic Padding to Reduce Compression Failures:Compression failures are expensive in terms of CPU. We go through the hoops of recompress, failure, reorganize, recompress, failure and finally page split. At the same time, how often we encounter compression failure depends largely on the compressibility of the data. In MySQL 5.6, courtesy of Facebook engineers, we have an adaptive algorithm based on per-index statistics that we gather about compression operations. The idea is that if a certain index/table is experiencing too many compression failures then we should try to pack the 16K uncompressed version of the page less densely i.e.: we let some space in the 16K page go unused in an attempt that the recompression won't end up in a failure. In other words, we dynamically keep adding 'pad' to the 16K page till we get compression failures within an agreeable range. It works the other way as well, that is we'll keep removing the pad if failure rate is fairly low. To tune the padding effort two configuration variables are exposed. innodb_compression_failure_threshold_pct: default 5, range 0 - 100,dynamic, implies the percentage of compress ops to fail before we start using to padding. Value 0 has a special meaning of disabling the padding. innodb_compression_pad_pct_max: default 50, range 0 - 75, dynamic, the  maximum percentage of uncompressed data page that can be reserved as pad.

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• Is creating a full application in Silverlight advisable?

  - by Anthony

  Is creating a huge public site fully in Silverlight really advisable? for eg. an ecommerce site. I don't want to start any debate but actually I feel Silverlight shouldn't be used for full website because the biggest loss you incur is of SEO. No search engines till today can parse the xap file and index it based on it's content. You can get around it by doing ifs and thens like if Silverlight is not supported then make an Asp.Net equivalent page for it but that only doubles our effort of making application, more than anything else. Why write double code in 2 applications meant for the same purpose. If that is the only option why not create Asp.Net application only. What are your views? Thanks in advance :)

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