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  • Silverlight Navigation using Mvvm-light(oobe)+MEF?

    - by deliberative assembly
    What is the best approach for navigating between UserControls/Pages(out of browser experience)? I'm fairly new to Silverlight and even newer to the mvvm pattern. How well does the Navigation Framework Integrate with the MVVM Light Toolkit? A snippet for general application flow control with the two would be great. The plan was to use the Navigation Framework for general flow or using Jeremy Likeness's approach to region management(http://csharperimage.jeremylikness.com/search/label/regions) and swapping out regions as needed. I've seen a few places mention replacing the Visual Root, but that sounded like a hack to me. Any advice, snippets, or a nudge in the general direction would be greatly appreciated. Thank you.

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  • Staging database good practices

    - by Tom
    Hi, I'm about to deploy to production a fairly complex site and for the first time need a staging environment where I can test things in a more realistic environment, especially with regard to some external services that cannot be run locally. My general plan is to develop & test first locally, push simple changes (small bug fixes, HTML/CSS, JS, etc) direct to production, and for larger changes, push first to staging subdomain for thorough testing and then to production. I don't think that I need to keep the staging and production databases in sync (occasional manual updating would do) but I'm wondering if there are any general good practices with regard to maintaing a staging environment in relation to a production environment, especially when it comes to databases. Any general thoughts/advice/experience would be appreciated.

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  • Is using Natural Join or Implicit column names not a good practice when writing SQL in a programming

    - by Jian Lin
    When we use Natural Join, we are joining the tables when both table have the same column names. But what if we write it in PHP and then the DBA add some more fields to both tables, then the Natural Join can break? The same goes for Insert, if we do a insert into gifts values (NULL, "chocolate", "choco.jpg", now()); then it will break the code as well as contaminating the table when the DBA adds some fields to the table (example as column 2 or 3). So it is always best to spell out the column names when the SQL statements are written inside a programming language and stored in a file in a big project.

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  • Why do mainframe greybeards refer to DB2/zOS as "he"? [closed]

    - by Alex Nauda
    If you ask a DB2/zOS engine DBA a question about DB2's behavior, the DBA will refer to the DB2 engine as "he" much the way a sailor uses "she" to refer to his ship. For example: "Once you fill the freespace, DB2 still wants to keep those rows in cluster order in the tablespace. That's why he'll split that page in half, and you end up with lots of half-empty pages. That is, unless the cluster key of the row you've just inserted is the highest in the table, in which case he makes a new empty page, and he puts just your new row into that page. So I wouldn't have to do this REORG if you would just sort your input like I suggested." Does anyone know where this tradition comes from?

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  • End User Ad-Hoc Reporting Tool: Microsoft SQL Server Management Studio or Microsoft Access?

    - by schultkl
    Our centralized IT department has suggested two primary ad hoc query tools for our general user base of approximately 200 staff members: Microsoft SQL Server Management Studio 2008 (SSMS) Microsoft Access 2003 Environment The backend database is a read-only Microsoft SQL Server 2005 database. The schema is 400+ tables; allowing access to the raw data for our general staff would be a disaster. We will be building an "abstraction layer" over the raw data for our general staff to run ad hoc queries against. The abstraction layer will most likely contain a number of views. A number of users have basic knowledge in Microsoft Access; none have used SSMS. Which of the above tools (or alternative) would be best for a decidedly non-techie user base of approximately 200 people? What are the pros and cons of each? Also, the IT department has suggested teaching people T-SQL so they may use SSMS. Is this reasonable?

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  • Ant database rebuild script, avoiding interactive prompting

    - by fras85
    Hi Guys. I'm writing an ant script to rebuild our database i.e. dropping everything and rebuilding from scratch. The problem our DBA adds a Y/N prompt before executing the rest of the script, and therefore we can't call this from an automated build process. Does anyone have any suggestions to circumvent the Y/N prompt? Obviously we could create seperate scripts, one for the DBA's and one for the automated build - but this requires maintaning both. We're running on Windows so it's not as easy as using sed to strip out the prompt...but i'm thinking something along those lines. Not sure if that's clear enough but hope you can help. Cheers.

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  • C# Linq: Can you merge DataContexts?

    - by Andreas Grech
    Say I have one database, and this database has a set of tables that are general to all Clients and some tables that are specific to certain clients. Now what I have in mind is creating a primary DataContext that includes only the tables that are general to all the clients, and then create separate DataContexts that contain only the tables that are specific to the client. Is there a way to kind of "merge" DataContexts so that it becomes one context? So for Client A, I need one DataContext that includes both the general tables and also the tables for that specific client (retrieved from two different DataContexts) ? [Update] What I think I can do is, from the Partial Class of the DataContext instead of letting my DataContext inherit from DataContext I make it inherit from MyDataContext; that way, the tables from MyDataContext and the other DataContext will be available in one DataContext class. What do you think about this approach? Of course with something like this you can only merge two datacontexts at once though...

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  • How to minimize the amount of place used by GPL copyright notice?

    - by Lukasz Lew
    Gnu GPL page advocates a following header in each file of GPL project: This file is part of Foobar. Foobar is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version. Foobar is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with Foobar. If not, see http://www.gnu.org/licenses/. I find this an over kill. Can't it be shorter and somehow refer to COPYING or LICENCE file?

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  • What exactly is saved in SQL Server Statistics? When they get updated? Is SQL Server itself is taking care of them?

    - by Pritesh
    I have been working with SQL Server as a Developer a while. One thing I learnt is SQL Server manages Statistics which help Engine to create optimized execution plan. I could not figure out what exactly is stores in Statistics? (I read it saves Vector, but what Vector?) When/In which scenario SQL Server updates Statistics? How/why some time they go out of sync (old Statistics) In case of old Statistics is a manual DBA/Developer intervention is required or SQL Server Will get them updated. As a DBA/Developer how to find out if Statistics OLD? What should we do?

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  • What's the best way to store custom objects in relational database?

    - by user342610
    I have my objects with their properties. Objects could change their structure: properties may be added/removed/changed. Objects could be absolutely dropped. So object's metadata (description, classes, call them like you want :) )could be changed. The database should store objects schemas and instances of these objects. What's the best way to organise a relational database structure to store data mentioned above? Currently I see only two ways: 1) Store objects schemas in a few tables: schema general data,schema properties, possible properties types. Store instances in their tables: instance general data, a few tables - per each type from possible properties types table to store instance properties data. And so on. 2) store objects schemas like in p1 but store instances like XML files in one table: one table for general instance info and one table with instance XML. please, don't ask why/for what I need this. Just need to store custom objects and DB should work fast :)

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  • How can I simulate a click event via script?

    - by Scott B
    I have a jquery accordion style menu that I'd like to add some shortcut links to across the top. When one of these shortcuts is clicked, it should have the same effect as if the user clicked the corresponding a tag that serves as that panel's header... Here's some code... <div> Application Shortcuts > <a href="" onclick="simulateAclick("generalSettings")>Open General Settings</a> </div> <ul class="menu collapsible"> <li class='header'><a href='#' id="generalSettings">General Settings</a> <ul class='acitem'>...stuff goes here... In the example above, clicking on "Open General Settings" toggles the "acitem" UL's child elements visible. I'd just like to simulate a click on that element, from a link at the top of my app...

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  • Windows Azure Learning Plan - Security

    - by BuckWoody
    This is one in a series of posts on a Windows Azure Learning Plan. You can find the main post here. This one deals with Security for  Windows Azure.   General Security Information Overview and general  information about Windows Azure Security - what it is, how it works, and where you can learn more. General Security Whitepaper – answers most questions http://blogs.msdn.com/b/usisvde/archive/2010/08/10/security-white-paper-on-windows-azure-answers-many-faq.aspx Windows Azure Security Notes from the Patterns and Practices site http://blogs.msdn.com/b/jmeier/archive/2010/08/03/now-available-azure-security-notes-pdf.aspx Overview of Azure Security http://www.windowsecurity.com/articles/Microsoft-Azure-Security-Cloud.html Azure Security Resources http://reddevnews.com/articles/2010/08/19/microsoft-releases-windows-azure-security-resources.aspx Cloud Computing Security Considerations http://www.microsoft.com/downloads/en/details.aspx?FamilyID=68fedf9c-1c27-4642-aa5b-0a34472303ea&utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+MicrosoftDownloadCenter+%28Microsoft+Download+Center Security in Cloud Computing – a Microsoft Perspective http://www.microsoft.com/downloads/en/details.aspx?FamilyID=7c8507e8-50ca-4693-aa5a-34b7c24f4579&utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+MicrosoftDownloadCenter+%28Microsoft+Download+Center Physical Security for Microsoft’s Online Computing Information on the Infrastructure and Locations for Azure Physical Security. The Global Foundation Services Group at Microsoft handles physical security http://www.globalfoundationservices.com/security/index.html Microsoft’s Security Response Center http://www.microsoft.com/security/msrc/ Software Security for Microsoft’s Online Computing Steps we take as a company to develop secure software Windows Azure is developed using the Trustworthy Computing Initiative http://www.microsoft.com/about/twc/en/us/default.aspx and  http://msdn.microsoft.com/en-us/library/ms995349.aspx Identity and Access in the Cloud http://blogs.msdn.com/b/technology_titbits_by_rajesh_makhija/archive/2010/10/29/identity-and-access-in-the-cloud.aspx Security Steps you should take While Microsoft takes great pains to secure the infrastructure, platform and code for Windows Azure, you have a responsibility to write secure code. These pointers can help you do that. Securing your cloud architecture, step-by-step http://technet.microsoft.com/en-us/magazine/gg296364.aspx Security Guidelines for Windows Azure http://redmondmag.com/articles/2010/06/15/microsoft-issues-security-guidelines-for-windows-azure.aspx  Best Practices for Windows Azure Security http://blogs.msdn.com/b/vbertocci/archive/2010/06/14/security-best-practices-for-developing-windows-azure-applications.aspx Active Directory and Windows Azure http://blogs.msdn.com/b/plankytronixx/archive/2010/10/22/projecting-your-active-directory-identity-to-the-azure-cloud.aspx Understanding Encryption (great overview and tutorial) http://blogs.msdn.com/b/plankytronixx/archive/2010/10/23/crypto-primer-understanding-encryption-public-private-key-signatures-and-certificates.aspx Securing your Connection Strings (SQL Azure) http://blogs.msdn.com/b/sqlazure/archive/2010/09/07/10058942.aspx Getting started with Windows Identity Foundation (WIF) quickly http://blogs.msdn.com/b/alikl/archive/2010/10/26/windows-identity-foundation-wif-fast-track.aspx

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  • SQL Server – Learning SQL Server Performance: Indexing Basics – Video

    - by pinaldave
    Today I remember one of my older cartoon years ago created for Indexing and Performance. Every single time when Performance is discussed, Indexes are mentioned along with it. In recent times, data and application complexity is continuously growing.  The demand for faster query response, performance, and scalability by organizations is increasing and developers and DBAs need to now write efficient code to achieve this. DBA and Developers A DBA’s role is critical, because a production environment has to run 24×7, hence maintenance, trouble shooting, and quick resolutions are the need of the hour.  The first baby step into any performance tuning exercise in SQL Server involves creating, analysing, and maintaining indexes. Though we have learnt indexing concepts from our college days, indexing implementation inside SQL Server can vary.  Understanding this behaviour and designing our applications appropriately will make sure the application is performed to its highest potential. Video Learning Vinod Kumar and myself we often thought about this and realized that practical understanding of the indexes is very important. One can not master every single aspects of the index. However there are some minimum expertise one should gain if performance is one of the concern. We decided to build a course which just addresses the practical aspects of the performance. In this course, we explored some of these indexing fundamentals and we elaborated on how SQL Server goes about using indexes.  At the end of this course of you will know the basic structure of indexes, practical insights into implementation, and maintenance tips and tricks revolving around indexes.  Finally, we will introduce SQL Server 2012 column store indexes.  We have refrained from discussing internal storage structure of the indexes but have taken a more practical, demo-oriented approach to explain these core concepts. Course Outline Here are salient topics of the course. We have explained every single concept along with a practical demonstration. Additionally shared our personal scripts along with the same. Introduction Fundamentals of Indexing Index Fundamentals Index Fundamentals – Visual Representation Practical Indexing Implementation Techniques Primary Key Over Indexing Duplicate Index Clustered Index Unique Index Included Columns Filtered Index Disabled Index Index Maintenance and Defragmentation Introduction to Columnstore Index Indexing Practical Performance Tips and Tricks Index and Page Types Index and Non Deterministic Columns Index and SET Values Importance of Clustered Index Effect of Compression and Fillfactor Index and Functions Dynamic Management Views (DMV) – Fillfactor Table Scan, Index Scan and Index Seek Index and Order of Columns Final Checklist: Index and Performance Well, we believe we have done our part, now waiting for your comments and feedback. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: PostADay, SQL, SQL Authority, SQL Index, SQL Performance, SQL Query, SQL Server, SQL Tips and Tricks, SQLServer, T SQL, Technology, Video

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  • "Rien n'est sécurisé sur le site Web de l'Hadopi" déclare Eric Walter, lors d'un débat sur les cyberguerriers

    "Rien n'est sécurisé sur le site Web de l'Hadopi" déclare Eric Walter, le secrétaire général était l'invité d'un débat sur les cyberguerriers Ce 8 février 2011 avait lieu dans un endroit huppé de la capitale un débat organisé par le Cercle, un réseau de 500 professionnels de la sécurité de l'information. Autour de la table, étaient réunis Olivier Laurelli, aka Bluetouff, blogueur spécialisé dans les problématiques liées à la sécurité et aux libertés individuelles ; Pierre Zanger, psychiatre et psychanalyste ; et Eric Walter, secrétaire général de l'Hadopi. Ce dernier, habituellement très contesté dans ce genre d'exercices, fut accueilli par ces mots de la part du "Monsieur Loyal" de la soirée :"Je n'ai pas ...

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  • ADNOC talks about 50x increase in performance

    - by KLaker
    If you are still wondering about how Exadata can revolutionise your business then I would recommend watching this great video which was recorded at this year's OpenWorld. First a little background...The Abu Dhabi National Oil Company for Distribution (ADNOC) is an integrated energy company that was founded in 1973. ADNOC Distribution markets and distributes petroleum products and services within the United Arab Emirates and internationally. As one of the largest and most innovative government-owned petroleum companies in the Arab Gulf, ADNOC Distribution is renowned and respected for the exceptional quality and reliability of its products and services. Its five corporate divisions include more than 200 filling stations (a number that is growing at 8% annually), more than 150 convenience stores, 10 vehicle inspection stations, as well as wholesale and retail sales of bulk fuel, gas, oil, diesel, and lubricants. ADNOC selected Oracle Exadata Database Machine after extensive research because it provided them with a single platform that can run mixed workloads in a single unified machine: "We chose Oracle Exadata Database Machine because it.offered a fully integrated and highly engineered system that was ready to deploy. With our infrastructure running all the same technology, we can operate any type of Oracle Database without restrictions and be prepared for business growth," said Ali Abdul Aziz Al-Ali, IT division manager, ADNOC Distribution. ".....we could consolidate our transaction processing and business intelligence onto one platform. Competing solutions are just not capable of doing that." - Awad Ahmed Ali El-Sidiq, Senior Database Administrator, ADNOC Distribution In this new video Awad Ahmen Ali El Sidddig, Senior DBA at ADNOC, talks about the impact that Exadata has had on his team and the whole business. ADNOC is using our engineered systems to drive and manage all their workloads: from transaction systems to payments system to data warehouse to BI environment. A true Disk-to-Dashboard revolution using Engineered Systems. This engineered approach is delivering 50x improvement in performance with one queries running 100x faster! The IT has even revolutionised some of their data warehouse related processes with the help of Exadata and now jobs that were taking over 4 hours now run in a few minutes.  To watch the video click on the image below which will take you to our Oracle YouTube page: (if the above link does not work, click here: http://www.youtube.com/watch?v=zcRpxc6u5Ic) Now that queries are running 100x faster and jobs are completing in minutes not hours, what is next for the IT team at ADNOC? Like many of our customers ADNOC is now looking to take advantage of big data to help them better align their business operations with customer behaviour and customer insights. To help deliver this next level of insight the IT team is looking at the new features in Oracle Database 12c such as the new in-memory feature to deliver even more performance gains.  The great news is that Awad Ahmen Ali El Sidddig was awarded DBA of the Year - EMEA within our Data Warehouse Global Leaders programme and you can see the badge for this award pop-up at the start of video. Well done to everyone at ADNOC and thanks for spending the time with us at OOW to create this great video.

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  • SQL SERVER – What the Business Says Is Not What the Business Wants

    - by pinaldave
    This blog post is written in response to T-SQL Tuesday hosted by Steve Jones. Steve raised a very interesting question; every DBA and Database Developer has already faced this situation. When I read the topic, I felt that I can write several different examples here. Today, I will cover this scenario, which seems quite amusing. Shrinking Database Earlier this year, I was working on SQL Server Performance Tuning consultancy; I had faced very interesting situation. No matter how much I attempt to reduce the fragmentation, I always end up with heavy fragmentation on the server. After careful research, I figured out that one of the jobs was continuously Shrinking the Database – which is a very bad practice. I have blogged about my experience over here SQL SERVER – SHRINKDATABASE For Every Database in the SQL Server. I removed the incorrect shrinking process right away; once it was removed, everything continued working as it should be. After a couple of days, I learned that one of their DBAs had put back the same DBCC process. I requested the Senior DBA to find out what is going on and he came up with the following reason: “Business Requirement.” I cannot believe this! Now, it was time for me to go deep into the subject. Moreover, it had become necessary to understand the need. After talking to the concerned people here, I understood what they needed. Please read the exact business need in their own language. The Shrinking “Business Need” “We shrink the database because if we take backup after shrinking the database, the size of the same is smaller. Once we take backup, we have to send it to our remote location site. Our business requirement is that we need to always make sure that the file is smallest when we transfer it to remote server.” The backup is not affected in any way if you shrink the database or not. The size of backup will be the same. After a couple of the tests, they agreed with me. Shrinking will create performance issues for the same as it will introduce heavy fragmentation in the database. The Real Solution The real business need was that they needed the smallest possible backup file. We finally implemented a quick solution which they are still using to date. The solution was compressed backup. I have written about this subject in detail few years before SQL SERVER – 2008 – Introduction to New Feature of Backup Compression. Compressed backup not only creates a small filesize but also increases the speed of the database as well. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Best Practices, Pinal Dave, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, SQLServer, T SQL, Technology

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  • EBS Techstack Sessions at OAUG/Collaborate 2010

    - by Steven Chan
    We have a large contingent of E-Business Suite Applications Technology Group staff rolling out to the OAUG/Collaborate 2010 conference in Las Vegas new week.  Our Applications Technology Group staff will be appearing as guest speakers or full-speakers at the following E-Business Suite technology stack related sessions:Database Special Interest GroupSunday, April 18, 11:00 AM, Breakers FSIG Leaders:  Michael Brown, Colibri; Sandra Vucinic, Vlad GroupGuest Speaker:  Steven ChanCovering database upcoming and past desupport dates, and database support policies as they apply to E-Business Suite environments, general Q&A E-Business Suite Technology Stack Special Interest GroupSunday, April 18, 3:00 PM, Breakers FSIG Leaders:  Elke Phelps, Paul Jackson, HumanaGuest Speaker:  Steven ChanCovering the latest EBS technology stack certifications, roadmap, desupport noticesupgrade options for Discoverer, OID, SSO, Portal, general Q&A E-Business Suite Applications Technology Roadmap & VisionMonday, April 19, 8:00 AM, South Seas GOracle Speaker:  Uma PrabhalaLatest developments for SOA, AOL, OAF, Web ADI, SES, AMP, ACMP, security, and other technologies Oracle E-Business Suite Applications Strategy and General Manager UpdateMonday, April 19, 2:30 PM, Mandalay Bay Ballroom DOracle Speaker:  Cliff GodwinUpdate on the entire Oracle E-Business Suite product line. The session covers the value delivered by the current release of Oracle E-Business Suite applications, the momentum, and how Oracle E-Business Suite applications integrate into Oracle's overall applications strategy 10 Things You Can Do Today to Prepare for the Next Generation ApplicationsTuesday, April 20, 8:00 AM, South Seas FOracle Speaker:  Nadia Bendjedou"Common sense" and "practical" steps that can be taken today to increase the value of your Oracle Applications (E-Business Suite, PeopleSoft, Siebel, and JDE) investments by using the latest Oracle solutions and technologiesReducing TCO using Oracle E-Business Suite Management PacksTuesday, April 20, 10:30 AM, South Seas EOracle Speaker:  Angelo RosadoLearn how you can reduce the Total Cost of Ownership by implementing Application Management Pack (AMP) and Application Change Management Pack (ACP) for E-Business Suite 11i, R12, R12.1. AMP is Oracle's next generation system manageability product offering that provides a centralized platform to manage and maintain EBS. ACP is Oracle's offering to monitor and manage E-Business Suite changes in the areas of E-Business Suite Customizations, Patches and Functional Setups. E-Business Suite Upgrade Special Interest GroupTuesday, April 20, 3:15 PM, South Seas ESIG Leaders:  John Stouffer; Sandra Vucinic, Vlad GroupGuest Speaker:  Steven ChanParticipating in general Q&A E-Business Suite Technology Essentials: Using the Latest Oracle Technologies with E-Business Suite Wednesday, April 21, 8:00 AM, South Seas HOracle Speaker:  Lisa ParekhOracle continues to build new functionality into the Oracle Database, Fusion Middleware, and Enterprise Manager. Come see how you can enhance the value of E-Business Suite for your users and lower your costs of ownership by utilizing the latest features of these Oracle technologies with E-Business Suite. Learn about the latest advanced E-Business Suite topologies and features, including new options for security, performance, third-party integration, SOA, virtualization, clouds, systems management, and much more How to Leverage the New E-Business Suite R12.1 Solutions Without Upgrading your 11.5.10 EnvironmentWednesday, April 21, 10:30 AMOracle Speaker:  Nadia Bendjedou, South Seas ELearn how you can use the latest E-Business Suite 12.1 standalone solutions without upgrading from your E-Business Suite 11.5.10 environment Web 2.0 User Experience and Oracle Fusion Middleware Integration with Oracle E-Business SuiteWednesday, April 21, 4:00 PM, South Seas FOracle Speaker:  Padmaprabodh AmbaleSee the next generation Oracle E-Business Suite OA framework improvements that will provide new rich interactions in components such as LOV, Tables and Attachments.  See  new components like the Rich Container that allows any Web 2.0 content like Flash or OBIEE to be embedded in OA Framework pages. Advanced Technology Deployment Architectures for E-Business Suite Wednesday, April 21, 2:15 PM, South Seas EOracle Speaker:  Steven ChanLearn how to take advantage of the latest version of Oracle Fusion Middleware with Oracle E-Business Suite. Learn how to utilize identity management systems and LDAP directories. In addition, come to this session for answers about advanced network deployments involving reverse proxy servers, load balancers, and DMZ's, and to see how you can take benefit from virtualization and new system management capabilities. Upgrading to Oracle E-Business Suite 12.1 - Best PracticesThursday, April 22, 11:00 AM, South Seas EOracle Speaker:  Lester Gutierrez, Udayan ParvateFundamental of upgrading to Release 12.1, which includes the technology stack components and differences, the upgrade path from various releases of Oracle E-Business Suite, upgrade steps, monitoring the upgrade, hints and tips for minimizing downtime and upgrade best practices for making the upgrade to Release 12.1 a success.  We look forward to seeing you there!

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  • Implementing algorithms via compute shaders vs. pipeline shaders

    - by TravisG
    With the availability of compute shaders for both DirectX and OpenGL it's now possible to implement many algorithms without going through the rasterization pipeline and instead use general purpose computing on the GPU to solve the problem. For some algorithms this seems to become the intuitive canonical solution because they're inherently not rasterization based, and rasterization-based shaders seemed to be a workaround to harness GPU power (simple example: creating a noise texture. No quad needs to be rasterized here). Given an algorithm that can be implemented both ways, are there general (potential) performance benefits over using compute shaders vs. going the normal route? Are there drawbacks that we should watch out for (for example, is there some kind of unusual overhead to switching from/to compute shaders at runtime)? Are there perhaps other benefits or drawbacks to consider when choosing between the two?

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  • New DMV… not yet

    - by Michael Zilberstein
    Downloaded and installed new toy: And while reading BOL, stumbled upon new extremely useful DMV: sys.dm_exec_query_profiles . This DMV enables DBA to monitor query progress while it is being executed. Counters in the DMV are per operation per thread. So we’ll be able to monitor in real time which thread (even for parallel processing) processes which node in the plan. Or find heavy operations “post mortem”. We all know the uncomfortable feeling when some heavy query runs and the boss starts asking...(read more)

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  • Best Practices - updated: which domain types should be used to run applications

    - by jsavit
    This post is one of a series of "best practices" notes for Oracle VM Server for SPARC (formerly named Logical Domains). This is an updated and enlarged version of the post on this topic originally posted October 2012. One frequent question "what type of domain should I use to run applications?" There used to be a simple answer: "run applications in guest domains in almost all cases", but now there are more things to consider. Enhancements to Oracle VM Server for SPARC and introduction of systems like the current SPARC servers including the T4 and T5 systems, the Oracle SuperCluster T5-8 and Oracle SuperCluster M6-32 provide scale and performance much higher than the original servers that ran domains. Single-CPU performance, I/O capacity, memory sizes, are much larger now, and far more demanding applications are now being hosted in logical domains. The general advice continues to be "use guest domains in almost all cases", meaning, "use virtual I/O rather than physical I/O", unless there is a specific reason to use the other domain types. The sections below will discuss the criteria for choosing between domain types. Review: division of labor and types of domain Oracle VM Server for SPARC offloads management and I/O functionality from the hypervisor to domains (also called virtual machines), providing a modern alternative to older VM architectures that use a "thick", monolithic hypervisor. This permits a simpler hypervisor design, which enhances reliability, and security. It also reduces single points of failure by assigning responsibilities to multiple system components, further improving reliability and security. Oracle VM Server for SPARC defines the following types of domain, each with their own roles: Control domain - management control point for the server, runs the logical domain daemon and constraints engine, and is used to configure domains and manage resources. The control domain is the first domain to boot on a power-up, is always an I/O domain, and is usually a service domain as well. It doesn't have to be, but there's no reason to not leverage it for virtual I/O services. There is one control domain per T-series system, and one per Physical Domain (PDom) on an M5-32 or M6-32 system. M5 and M6 systems can be physically domained, with logical domains within the physical ones. I/O domain - a domain that has been assigned physical I/O devices. The devices may be one more more PCIe root complexes (in which case the domain is also called a root complex domain). The domain has native access to all the devices on the assigned PCIe buses. The devices can be any device type supported by Solaris on the hardware platform. a SR-IOV (Single-Root I/O Virtualization) function. SR-IOV lets a physical device (also called a physical function) or PF) be subdivided into multiple virtual functions (VFs) which can be individually assigned directly to domains. SR-IOV devices currently can be Ethernet or InfiniBand devices. direct I/O ownership of one or more PCI devices residing in a PCIe bus slot. The domain has direct access to the individual devices An I/O domain has native performance and functionality for the devices it owns, unmediated by any virtualization layer. It may also have virtual devices. Service domain - a domain that provides virtual network and disk devices to guest domains. The services are defined by commands that are run in the control domain. It usually is an I/O domain as well, in order for it to have devices to virtualize and serve out. Guest domain - a domain whose devices are all virtual rather than physical: virtual network and disk devices provided by one or more service domains. In common practice, this is where applications are run. Device considerations Consider the following when choosing between virtual devices and physical devices: Virtual devices provide the best flexibility - they can be dynamically added to and removed from a running domain, and you can have a large number of them up to a per-domain device limit. Virtual devices are compatible with live migration - domains that exclusively have virtual devices can be live migrated between servers supporting domains. On the other hand: Physical devices provide the best performance - in fact, native "bare metal" performance. Virtual devices approach physical device throughput and latency, especially with virtual network devices that can now saturate 10GbE links, but physical devices are still faster. Physical I/O devices do not add load to service domains - all the I/O goes directly from the I/O domain to the device, while virtual I/O goes through service domains, which must be provided sufficient CPU and memory capacity. Physical I/O devices can be other than network and disk - we virtualize network, disk, and serial console, but physical devices can be the wide range of attachable certified devices, including things like tape and CDROM/DVD devices. In some cases the lines are now blurred: virtual devices have better performance than previously: starting with Oracle VM Server for SPARC 3.1 there is near-native virtual network performance. There is more flexibility with physical devices than before: SR-IOV devices can now be dynamically reconfigured on domains. Tradeoffs one used to have to make are now relaxed: you can often have the flexibility of virtual I/O with performance that previously required physical I/O. You can have the performance and isolation of SR-IOV with the ability to dynamically reconfigure it, just like with virtual devices. Typical deployment A service domain is generally also an I/O domain: otherwise it wouldn't have access to physical device "backends" to offer to its clients. Similarly, an I/O domain is also typically a service domain in order to leverage the available PCI buses. Control domains must be I/O domains, because they boot up first on the server and require physical I/O. It's typical for the control domain to also be a service domain too so it doesn't "waste" the I/O resources it uses. A simple configuration consists of a control domain that is also the one I/O and service domain, and some number of guest domains using virtual I/O. In production, customers typically use multiple domains with I/O and service roles to eliminate single points of failure, as described in Availability Best Practices - Avoiding Single Points of Failure . Guest domains have virtual disk and virtual devices provisioned from more than one service domain, so failure of a service domain or I/O path or device does not result in an application outage. This also permits "rolling upgrades" in which service domains are upgraded one at a time while their guests continue to operate without disruption. (It should be noted that resiliency to I/O device failures can also be provided by the single control domain, using multi-path I/O) In this type of deployment, control, I/O, and service domains are used for virtualization infrastructure, while applications run in guest domains. Changing application deployment patterns The above model has been widely and successfully used, but more configuration options are available now. Servers got bigger than the original T2000 class machines with 2 I/O buses, so there is more I/O capacity that can be used for applications. Increased server capacity made it attractive to run more vertically-scaled applications, such as databases, with higher resource requirements than the "light" applications originally seen. This made it attractive to run applications in I/O domains so they could get bare-metal native I/O performance. This is leveraged by the Oracle SuperCluster engineered systems mentioned previously. In those engineered systems, I/O domains are used for high performance applications with native I/O performance for disk and network and optimized access to the Infiniband fabric. Another technical enhancement is Single Root I/O Virtualization (SR-IOV), which make it possible to give domains direct connections and native I/O performance for selected I/O devices. Not all I/O domains own PCI complexes, and there are increasingly more I/O domains that are not service domains. They use their I/O connectivity for performance for their own applications. However, there are some limitations and considerations: at this time, a domain using physical I/O cannot be live-migrated to another server. There is also a need to plan for security and introducing unneeded dependencies: if an I/O domain is also a service domain providing virtual I/O to guests, it has the ability to affect the correct operation of its client guest domains. This is even more relevant for the control domain. where the ldm command must be protected from unauthorized (or even mistaken) use that would affect other domains. As a general rule, running applications in the service domain or the control domain should be avoided. For reference, an excellent guide to secure deployment of domains by Stefan Hinker is at Secure Deployment of Oracle VM Server for SPARC. To recap: Guest domains with virtual I/O still provide the greatest operational flexibility, including features like live migration. They should be considered the default domain type to use unless there is a specific requirement that mandates an I/O domain. I/O domains can be used for applications with the highest performance requirements. Single Root I/O Virtualization (SR-IOV) makes this more attractive by giving direct I/O access to more domains, and by permitting dynamic reconfiguration of SR-IOV devices. Today's larger systems provide multiple PCIe buses - for example, 16 buses on the T5-8 - making it possible to configure multiple I/O domains each owning their own bus. Service domains should in general not be used for applications, because compromised security in the domain, or an outage, can affect domains that depend on it. This concern can be mitigated by providing guests' their virtual I/O from more than one service domain, so interruption of service in one service domain does not cause an application outage. The control domain should in general not be used to run applications, for the same reason. Oracle SuperCluster uses the control domain for applications, but it is an exception. It's not a general purpose environment; it's an engineered system with specifically configured applications and optimization for optimal performance. These are recommended "best practices" based on conversations with a number of Oracle architects. Keep in mind that "one size does not fit all", so you should evaluate these practices in the context of your own requirements. Summary Higher capacity servers that run Oracle VM Server for SPARC are attractive for applications with the most demanding resource requirements. New deployment models permit native I/O performance for demanding applications by running them in I/O domains with direct access to their devices. This is leveraged in SPARC SuperCluster, and can be leveraged in T-series servers to provision high-performance applications running in domains. Carefully planned, this can be used to provide peak performance for critical applications. That said, the improved virtual device performance in Oracle VM Server means that the default choice should still be guest domains with virtual I/O.

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  • Need to Know

    - by Tony Davis
    Sometimes, I wonder whether writers of documentation, tutorials and articles stop to ask themselves one very important question: Does the reader really need to know this? I recently took on the task of writing a concise series of articles about the transaction log, what is it, how it works and why it's important. It was an enjoyable task; rather like peering inside a giant, complex clock mechanism. Initially, one sees only the basic components, which work to guarantee the integrity of database transactions, and preserve these transactions so that data can be restored to a previous point in time. On closer inspection, one notices all of small, arcane mechanisms that are necessary to make this happen; LSNs, virtual log files, log chains, database checkpoints, and so on. It was engrossing, escapist, stuff; what I'd written looked weighty and steeped in mysterious significance. Suddenly, however, I jolted myself back to reality with the awful thought "does anyone really need to know all this?" The driver of a car needs only to be dimly aware of what goes on under the hood, however exciting the mechanism is to the engineer. Similarly, while everyone who uses SQL Server ought to be aware of the transaction log, its role in guaranteeing the ACID properties, and how to control its growth, the intricate mechanisms ticking away under its clock face are a world away from the daily work of the harassed developer. The DBA needs to know more, such as the correct rituals for ensuring optimal performance and data integrity, setting the appropriate growth characteristics, backup routines, restore procedures, and so on. However, even then, the average DBA only needs to understand enough about the arcane processes to spot problems and react appropriately, or to know how to Google for the best way of dealing with it. The art of technical writing is tied up in intimate knowledge of your audience and what they need to know at any point. It means serving up just enough at each point to help the reader in a practical way, but not to overcook it, or stuff the reader with information that does them no good. When I think of the books and articles that have helped me the most, they have been full of brief, practical, and well-informed guidance, based on experience. This seems far-removed from the 900-page "beginner's guides" that one now sees everywhere. The more I write and edit, the more I become convinced that the real art of technical communication lies in knowing what to leave out. In what areas do the SQL Server technical materials suffer from "information overload"? Where else does it seem that concise, practical advice is drowned out by endless discussion of the "clock mechanisms"? Cheers, Tony.

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