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  • CodePlex Daily Summary for Sunday, September 02, 2012

    CodePlex Daily Summary for Sunday, September 02, 2012Popular ReleasesThisismyusername's codeplex page.: HTML5 Multitouch Example - Fruit Ninja in HTML5: This is an example of how you could create a game such as Fruit Ninja using HTML5's multitouch capabilities. This example isn't responsive enough, so I will be working on that, and it doesn't have great graphics, either. If I had my own webpage, I could store some graphics and upload the game there and it might look halfway decent, but here the fruits are just circles. I hope you enjoy reading the source code anyway.GmailDefaultMaker: GmailDefaultMaker 3.0.0.2: Add QQ Mail BugfixRuminate XNA 4.0 GUI: Release 1.1.1: Fixed bugs with Slider and TextBox. Added ComboBox.Confuser: Confuser build 76542: This is a build of changeset 76542.SharePoint Column & View Permission: SharePoint Column and View Permission v1.2: Version 1.2 of this project. If you will find any bugs please let me know at enti@zoznam.sk or post your findings in Issue TrackerMihmojsos OS: Mihmojsos OS 3 (Smart Rabbit): !Mihmojsos OS 3 Smart Rabbit Mihmojsos Smart Rabbit is now availableDotNetNuke Translator: 01.00.00 Beta: First release of the project.YNA: YNA 0.2 alpha: Wath's new since 0.1 alpha ? A lot of changes but there are the most interresting : StateManager is now better and faster Mouse events for all YnObjects (Sprites, Images, texts) A really big improvement for YnGroup Gamepad support And the news : Tiled Map support (need refactoring) Isometric tiled map support (need refactoring) Transition effect like "FadeIn" and "FadeOut" (YnTransition) Timers (YnTimer) Path management (YnPath, need more refactoring) Downloads All downloads...Audio Pitch & Shift: Audio Pitch And Shift 5.1.0.2: fixed several issues with streaming modeUrlPager: UrlPager 1.2: Fixed bug in which url parameters will lost after paging; ????????url???bug;Sofire Suite: Sofire v1.5.0.0: Sofire v1.5.0.0 ?? ???????? ?????: 1、?? 2、????EntLib.com????????: EntLib.com???????? v3.0: EntLib eCommerce Solution ???Microsoft .Net Framework?????????????????????。Coevery - Free CRM: Coevery 1.0.0.24: Add a sample database, and installation instructions.Math.NET Numerics: Math.NET Numerics v2.2.1: Major linear algebra rework since v2.1, now available on Codeplex as well (previous versions were only available via NuGet). Since v2.2.0: Student-T density more robust for very large degrees of freedom Sparse Kronecker product much more efficient (now leverages sparsity) Direct access to raw matrix storage implementations for advanced extensibility Now also separate package for signed core library with a strong name (we dropped strong names in v2.2.0) Also available as NuGet packages...Microsoft SQL Server Product Samples: Database: AdventureWorks Databases – 2012, 2008R2 and 2008: About this release This release consolidates AdventureWorks databases for SQL Server 2012, 2008R2 and 2008 versions to one page. Each zip file contains an mdf database file and ldf log file. This should make it easier to find and download AdventureWorks databases since all OLTP versions are on one page. There are no database schema changes. For each release of the product, there is a light-weight and full version of the AdventureWorks sample database. The light-weight version is denoted by ...Christoc's DotNetNuke Module Development Template: DotNetNuke Project Templates V1.1 for VS2012: This release is specifically for Visual Studio 2012 Support, distributed through the Visual Studio Extensions gallery at http://visualstudiogallery.msdn.microsoft.com/ After you build in Release mode the installable packages (source/install) can be found in the INSTALL folder now, within your module's folder, not the packages folder anymore Check out the blog post for all of the details about this release. http://www.dotnetnuke.com/Resources/Blogs/EntryId/3471/New-Visual-Studio-2012-Projec...Home Access Plus+: v8.0: v8.0.0901.1830 RELEASE CHANGED TO BETA Any issues, please log them on http://www.edugeek.net/forums/home-access-plus/ This is full release, NO upgrade ZIP will be provided as most files require replacing. To upgrade from a previous version, delete everything but your AppData folder, extract all but the AppData folder and run your HAP+ install Documentation is supplied in the Web Zip The Quota Services require executing a script to register the service, this can be found in there install ...Phalanger - The PHP Language Compiler for the .NET Framework: 3.0.0.3406 (September 2012): New features: Extended ReflectionClass libxml error handling, constants DateTime::modify(), DateTime::getOffset() TreatWarningsAsErrors MSBuild option OnlyPrecompiledCode configuration option; allows to use only compiled code Fixes: ArgsAware exception fix accessing .NET properties bug fix ASP.NET session handler fix for OutOfProc mode DateTime methods (WordPress posting fix) Phalanger Tools for Visual Studio: Visual Studio 2010 & 2012 New debugger engine, PHP-like debugging ...MabiCommerce: MabiCommerce 1.0.1: What's NewSetup now creates shortcuts Fix spelling errors Minor enhancement to the Map window.ScintillaNET: ScintillaNET 2.5.2: This release has been built from the 2.5 branch. Version 2.5.2 is functionally identical to the 2.5.1 release but also includes the XML documentation comments file generated by Visual Studio. It is not 100% comprehensive but it will give you Visual Studio IntelliSense for a large part of the API. Just make sure the ScintillaNET.xml file is in the same folder as the ScintillaNET.dll reference you're using in your projects. (The XML file does not need to be distributed with your application)....New ProjectsATSV: this is a student project for making a new silverlight UI Bookmark Collector: This project is a best practice example of how to use content items in DotNetNuke. It allows you to quickly and easily manage a listing of external links.BPVotingmachine: BP Vote SystemClean My Space: Sort your files in a fun and fast! With Clean My Space you can!CutePlatform: CutePlatform is a platform game based around the PlanetCute graphics pack from Daniel cook, make him a visit in www.lostgardem.comDancTeX: This project is targeting the integration of LaTeX into VisusalStudio. Epi Info™ Companion for Android: A mobile companion to the Epi Info™ 7 desktop tool for epidemiologic data collection and analysis.Flucene: Object Document Mapper for Lucene.Netfluentserializer: FluentSerializer is a library for .NET usable to create serialize/deserialize data through its fluent interface. The methods it creates are compiled.hongjiapp: hongjiappidealthings educational comprehensive administration system: ?????????????????????????????????????????????.Java Accounting Library: The project aims at providing a Financial Accounting Java Library which may be integrated to any other Java Application independent of its Backend Database.mycnblogs: mycnblogsNETPack: Lightweight and flexible packer for .NETRandom Useful Code: This project is where I will store various useful classes I have built over time. Only the code will be provided, no Library or the like.Suleymaniye Tavimi: Namaz vakitleri hesaplama uygulamasidir. Istenilen yer için hesaplama yapar.

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  • Intro to MySQL Proxy

    It's no surprise that the concept of a proxy has made its way into the database arena. The MySQL Proxy sits between your application and your MySQL database. Future articles will discuss the myriad of uses for this technology.

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  • An XEvent a Day (28 of 31) – Tracking Page Compression Operations

    - by Jonathan Kehayias
    The Database Compression feature in SQL Server 2008 Enterprise Edition can provide some significant reductions in storage requirements for SQL Server databases, and in the right implementations and scenarios performance improvements as well.  There isn’t really a whole lot of information about the operations of database compression that is documented as being available in the DMV’s or SQL Trace.  Paul Randal pointed out on Twitter today that sys.dm_db_index_operational_stats() provides...(read more)

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  • SQLAuthority News Download Microsoft SQL Server JDBC Driver 3.0 CTP 1

    Download the SQL Server JDBC Driver 3.0 CTP, a Type 4 JDBC driver that provides database connectivity through the standard JDBC application program interfaces (APIs) available in Java Platform, Enterprise Edition 5.In its continued commitment to interoperability, Microsoft has released a preview of the upcoming Java Database Connectivity (JDBC) driver. The SQL Server JDBC Driver [...]...Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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  • Stairway to XML: Level 2 - The XML Data Type

    Robert Sheldon describes SQL Server's XML Data Type, and shows that it is as easy to configure a variable, column, or parameter with the XML data type as configuring one of these objects with any other datatype Keep your database and application development in syncSQL Connect is a Visual Studio add-in that brings your databases into your solution. It then makes it easy to keep your database in sync, and commit to your existing source control system. Find out more.

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  • Why was Android's ContentProvider created?

    - by satur9nine
    The title sums up my question, but to elaborate basically what I want to understand is why the Android designers want apps that need to work with shared data to use a Content Provider rather than just accessing the SQLite database directly? The only reason I can think of is security because certain files can by accessed only be certain processes and in that way the Content Provider is the gatekeeper that ensures each app has the proper privileges before allowing read and/or write access to the database file. Is that the primary reason why ContentProvider was created?

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  • Bay Area Coherence Special Interest Group Next Meeting July 21, 2011

    - by csoto
    Date: Thursday, July 21, 2011 Time: 4:30pm - 8:15pm ET (note that Parking at 475 Sansome Closes at 8:30pm) Where: Oracle Office, 475 Sansome Street, San Francisco, CA Google Map We will be providing snacks and beverages. Register! - Registration is required for building security. Presentation Line Up:? 5:10pm - Batch Processing Using Coherence in Oracle Group Policy Administration - Paul Cleary, Oracle Oracle Insurance Policy Administration (OIPA) is a flexible, rules-based policy administration solution that provides full record keeping for all policy lifecycle transactions. One component of OIPA is Cycle processing, which is the batch processing of pending insurance transactions. This presentation introduces OIPA and Cycle processing, describing the unique challenges of processing a high volume of transactions within strict time windows. It then reviews how OIPA uses Oracle Coherence and the Processing Pattern to meet these challenges, describing implementation specifics that highlight the simplicity and robustness of the Processing Pattern. 6:10pm - Secure, Optimize, and Load Balance Coherence with F5 - Chris Akker, F5 F5 Networks, Inc., the global leader in Application Delivery Networking, helps the world’s largest enterprises and service providers realize the full value of virtualization, cloud computing, and on-demand IT. Recently, F5 and Oracle partnered to deliver a novel solution that integrates Oracle Coherence 3.7 with F5 BIG-IP Local Traffic Manager (LTM). This session will introduce F5 and how you can leverage BIG-IP LTM to secure, optimize, and load balance application traffic generated from Coherence*Extend clients across any number of servers in a cluster and to hardware-accelerate CPU-intensive SSL encryption. 7:10pm - Using Oracle Coherence to Enable Database Partitioning and DC Level Fault Tolerance - Alexei Ragozin, Independent Consultant and Brian Oliver, Oracle Partitioning is a very powerful technique for scaling database centric applications. One tricky part of partitioned architecture is routing of requests to the right database. The routing layer (routing table) should know the right database instance for each attribute which may be used for routing (e.g. account id, login, email, etc): it should be fast, it should fault tolerant and it should scale. All the above makes Oracle Coherence a natural choice for implementing such routing tables in partitioned architectures. This presentation will cover synchronization of the grid with multiple databases, conflict resolution, cross cluster replication and other aspects related to implementing robust partitioned architecture. Additional Info:?? - Download Past Presentations: The presentations from the previous meetings of the BACSIG are available for download here. Click on the presentation titles to download the PDF files. - Join the Coherence online community on our Oracle Coherence Users Group on LinkedIn. - Contact BACSIG with any comments, questions, presentation proposals and content suggestions.

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  • Devoxx 2011: Java EE 6 Hands-on Lab Delivered

    - by arungupta
    I, along with Alexis's help, delivered a Java EE 6 hands-on lab to a packed room of about 40+ attendees at Devoxx 2011. The lab was derived from the OTN Developer Days 2012 version but added lot more content to showcase several Java EE 6 technologies. The problem statement from the lab document states: This hands-on lab builds a typical 3-tier Java EE 6 Web application that retrieves customer information from a database and displays it in a Web page. The application also allows new customers to be added to the database as well. The string-based and type-safe queries are used to query and add rows to the database. Each row in the database table is published as a RESTful resource and is then accessed programmatically. Typical design patterns required by a Web application like validation, caching, observer, partial page rendering, and cross-cutting concerns like logging are explained and implemented using different Java EE 6 technologies. The lab covered Java Persistence API 2, Servlet 3, Enterprise JavaBeans 3.1, JavaServer Faces 2, Java API for RESTful Web Services 1.1, Contexts and Dependency Injection 1.0, and Bean Validation 1.0 over 47 pages of detailed self-paced instructions. Here is the complete Table of Contents: The lab can be downloaded from here and requires only NetBeans IDE "All" or "Java EE" version, which includes GlassFish anyway. All the feedback received from the lab has been incorporated in the instructions and bugs filed (Updated 49559, 205232, 205248, 205256). 80% of the attendees could easily complete the lab and some even completed in much less than 3 hours. That indicates that either more content needs to be added to the lab or the intellectual level of the attendees at the conference was pretty high. I think the lab has enough content for 3 hours but we moved at a much more faster pace so I conclude on the latter. Truly a joy to conduct a lab to 40 Devoxxians! Another related lab that might be handy for folks is "Develop, Deploy, and Monitor your Java EE 6 applications using GlassFish 3.1 Cluster". It explains how: Create a 2-instance GlassFish cluster Front-end with a Web server and a load balancer Demonstrate session replication and fail over Monitor the application using JavaScript The complete lab instructions and source code are available and you can try them. I plan to continue evolving the contents for the Java EE 6 hands-on lab to cover more technologies and features and will announce them on this blog. Let me know on what else would you like to see in the future versions.

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  • Devoxx 2011: Java EE 6 Hands-on Lab Delivered

    - by arungupta
    I, along with Alexis's help, delivered a Java EE 6 hands-on lab to a packed room of about 40+ attendees at Devoxx 2011. The lab was derived from the OTN Developer Days 2012 version but added lot more content to showcase several Java EE 6 technologies. The problem statement from the lab document states: This hands-on lab builds a typical 3-tier Java EE 6 Web application that retrieves customer information from a database and displays it in a Web page. The application also allows new customers to be added to the database as well. The string-based and type-safe queries are used to query and add rows to the database. Each row in the database table is published as a RESTful resource and is then accessed programmatically. Typical design patterns required by a Web application like validation, caching, observer, partial page rendering, and cross-cutting concerns like logging are explained and implemented using different Java EE 6 technologies. The lab covered Java Persistence API 2, Servlet 3, Enterprise JavaBeans 3.1, JavaServer Faces 2, Java API for RESTful Web Services 1.1, Contexts and Dependency Injection 1.0, and Bean Validation 1.0 over 47 pages of detailed self-paced instructions. Here is the complete Table of Contents: The lab can be downloaded from here and requires only NetBeans IDE "All" or "Java EE" version, which includes GlassFish anyway. All the feedback received from the lab has been incorporated in the instructions and bugs filed (Updated 49559, 205232, 205248, 205256). 80% of the attendees could easily complete the lab and some even completed in much less than 3 hours. That indicates that either more content needs to be added to the lab or the intellectual level of the attendees at the conference was pretty high. I think the lab has enough content for 3 hours but we moved at a much more faster pace so I conclude on the latter. Truly a joy to conduct a lab to 40 Devoxxians! Another related lab that might be handy for folks is "Develop, Deploy, and Monitor your Java EE 6 applications using GlassFish 3.1 Cluster". It explains how: Create a 2-instance GlassFish cluster Front-end with a Web server and a load balancer Demonstrate session replication and fail over Monitor the application using JavaScript The complete lab instructions and source code are available and you can try them. I plan to continue evolving the contents for the Java EE 6 hands-on lab to cover more technologies and features and will announce them on this blog. Let me know on what else would you like to see in the future versions.

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  • Notifying a separate application of an event

    - by TomDestry
    I have an application that runs through various tasks as an automated process. My client would like me to create a file in a given folder for each task as a way to flag when each task completes. They prefer this to a database flag because they can be notified by the file system rather than continually polling a database table. I can do this but creating and deleting files as flags feels clunky. Is there a more elegant approach to notifying a third-party of an event?

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  • Oracle Develop 2011 - Moscow and Hyderabad Editions

    - by Cassandra Clark
    Connect with Oracle developers at Oracle Develop - Oracle Develop will be held in Moscow, April 12-13th, 2011 and again in Hyderabad, May 10th - 11th, 2011. Enjoy two days of technical content and hands-on learning focused on Oracle products and next-generation development trends and technologies, including rich enterprise applications (REAs), service-oriented architecture (SOA), and the database.Oracle Develop Moscow Tracks - Database DevelopmentApplication Infrastructure and Oracle WeblogicOracle Fusion Development and Rich Enterprise ApplicationsService Oriented ArchitectureOracle Develop Hyderabad Tracks - Application Grid and Oracle WeblogicDatabase DevelopmentOracle Fusion Development and Rich Enterprise ApplicationsService Oriented Architecture.NET with Oracle DatabaseRegister Now for Oracle Develop Moscow!Register Now for Oracle Develop Hyderabad!

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  • Columnar Databases

    - by jchang
    Ingres just published a TPC-H benchmark for VectorWise , an analytic database technology employing 1) SIMD processing (Intel SSE 4.2), 2) better memory optimizations to leverage on-chip cache, 3) compression, 4) Column-based storage. Ingres originated as a research project at UC Berkeley (see Wikipedia ) in the 1970s, and has since become a commercially supported, open source database system. Apparently, Ingres project people later founded Sybase. So Ingres in a sense, is the grandfather (or perhap...(read more)

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  • How to use Object Type Converter

    - by arun.x.sridharan(at)oracle.com
    UseCase Description A person form where in user will enter String which has to be converted to Number while persisting. From the User Interface we might be getting a String value which has to be persisted in the database as a number in that scenario we can use converters to map the java object which is of type String to its database value which is a Number. For example , there is a 'Person' table in database which is used to store the user details passed from the User Interface. It has a 'Status' column which is of the value  Number. But from the User Interface String values (Active/InActive) are passed . For persisting the user details we can use Object type converter and provide the mappings for status column corresponding to the String values. Object type converter can be used if you wanted to have a mapping for a field for example when departmentName on the entity was of String value and mapped to dept_name field on the database table which is of the value NUMBER.   Implementation steps Sample EJB API for setting the value of status on Person Entity as a String     public void createPerson(String status,String firstName,String lastName) {                Person person = new Person();                // status will be set as a String value received from the User Interface         person.setStatus(status);                person.setFirstname(firstName);        person.setLastname(lastName);                persistPerson(person);         } In the sample code shown above status is passed as a String, this has to be converted to Number. The String value obtained will be set on Person object and persistPerson API will be called for creating a new person from the values passed from the User Interface.  Steps to configure Object type converter: 1. Navigate to Person Entity from persistence.xml and navigate to status field2. Click on Conversion tab and select Converted check box3. Select Object Type Converter radio button and set the Data Type Class to      java.math.BigDecimal and Object Type Class to java.lang.String4. Specify the conversion values for all the values that can be passed from the user interface  as shown below5. Set the Default Object value

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  • Happy 10th Anniversary to AskTom!

    - by jenny.gelhausen
    Happy Anniversary to Tom Kyte's AskTom.oracle.com! Ten years of nuturing and advising the Oracle Database community is certainly a milestone to celebrate. With your first question being asked and answered in early 2000 about Oracle 7.3 on a Sun 5.5.1 machine - we recognize and appreciate the value of AskTom's informaton and insight to the industry. Well done and THANK YOU Tom! the Database Insider Team

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  • Speaking at Atlanta.MDF on March 12

    - by RickHeiges
    I am fortunate enough to be speaking to a user group with a really cool name - Atlanta.MDF (Microsoft Database Forum). Although I visit Atlanta often, it usually involves running from one councourse to another and rarely do I get the chance to visit the user group. I have made it to the user group on several occassions in the past, but it has been several years. This will be my first presentation to the group. I will be speaking about Database Consolidation - something I have been doing for years....(read more)

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  • Need your feedback on our new SQL Server Connectivity portal

    - by The Official Microsoft IIS Site
    SQL Server, as a database product, has grown over the years and there are multiple ways to connect to it. Often, the different ways to connect to the database get documented and discussed in the various technology sections, and the technology choice determines which connectivity method one is going to use. For example, if one is writing a C++ application then one has to go with ODBC whereas a PHP web site developer will choose the PHP driver of course. Until now, this information was scattered all...(read more)

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  • Oracle as a Data Source

    This article takes a quick look at Oracle database's materialized view and extends the concept of that feature to a case where Oracle is the data source for another relational database management system.

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  • Stairway to Transaction Log Management in SQL Server, Level 1: Transaction Log Overview

    The transaction log is used by SQL Server to maintain data consistency and integrity. If the database is not in Simple-recovery mode, it can also be used in an appropriate backup regime to restore the database to a point in time. The Future of SQL Server Monitoring "Being web-based, SQL Monitor enables you to check on your servers from almost any location" Jonathan Allen.Try SQL Monitor now.

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  • SQL in the City - Austin 2012

    A free day of training in Austin, TX with Grant Fritchey, Steve Jones and a few others. Join us to learn about SQL Server and how you can more efficiently work in your job every day. Learn Agile Database Development Best PracticesAgile database development experts Sebastian Meine and Dennis Lloyd are running day-long classes designed to complement Red Gate’s SQL in the City US tour. Classes will be held in San Francisco, Chicago, Boston and Seattle. Register Now.

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  • Oracle Magazine, March/April 2009

    Oracle Magazine March/April features articles on next-generation data centers, Oracle and midsize businesses, efficient business processes, improving performance and management of Oracle Database 11g, managing Oracle Application Express, Technologist Tom Kyte, Oracle ADF, PL/SQL best practices, the HP Oracle Database Machine, security with Oracle Configuration Manager and much more.

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  • What permissions are required for SET IDENTITY_INSERT ON?

    - by AaronBertrand
    SQL Server 2000's SET IDENTITY_INSERT ON topic says: Execute permissions default to the sysadmin fixed server role, and the db_owner and db_ddladmin fixed database roles, and the object owner. While the SET IDENTITY_INSERT topic for SQL Server 2005 (and up) says: User must own the object, or be a member of the sysadmin fixed server role, or the db_owner and db_ddladmin fixed database roles. This was clearly adapted from the 2000 books online and re-written by someone who misinterpreted "db_owner...(read more)

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  • What are some options and methods to link a contact form on WordPress to an existing form processing script?

    - by eirlymeyer
    I’m searching for the best way to link the outgoing/output data in a WordPress contact form plugin on a WordPress website to an existing MySQL database where a contact form is processed. Scenario: A new site (Site A) is being developed with a contact form. Site B (old site) uses a contact form script to process contact form leads through an existing legacy database and a ColdFusion application. The goal is to create site A with a new contact form to continue the same existing processes. Site A is to become the new Site B.

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  • Master-slave vs. peer-to-peer archictecture: benefits and problems

    - by Ashok_Ora
    Normal 0 false false false EN-US X-NONE X-NONE Almost two decades ago, I was a member of a database development team that introduced adaptive locking. Locking, the most popular concurrency control technique in database systems, is pessimistic. Locking ensures that two or more conflicting operations on the same data item don’t “trample” on each other’s toes, resulting in data corruption. In a nutshell, here’s the issue we were trying to address. In everyday life, traffic lights serve the same purpose. They ensure that traffic flows smoothly and when everyone follows the rules, there are no accidents at intersections. As I mentioned earlier, the problem with typical locking protocols is that they are pessimistic. Regardless of whether there is another conflicting operation in the system or not, you have to hold a lock! Acquiring and releasing locks can be quite expensive, depending on how many objects the transaction touches. Every transaction has to pay this penalty. To use the earlier traffic light analogy, if you have ever waited at a red light in the middle of nowhere with no one on the road, wondering why you need to wait when there’s clearly no danger of a collision, you know what I mean. The adaptive locking scheme that we invented was able to minimize the number of locks that a transaction held, by detecting whether there were one or more transactions that needed conflicting eyou could get by without holding any lock at all. In many “well-behaved” workloads, there are few conflicts, so this optimization is a huge win. If, on the other hand, there are many concurrent, conflicting requests, the algorithm gracefully degrades to the “normal” behavior with minimal cost. We were able to reduce the number of lock requests per TPC-B transaction from 178 requests down to 2! Wow! This is a dramatic improvement in concurrency as well as transaction latency. The lesson from this exercise was that if you can identify the common scenario and optimize for that case so that only the uncommon scenarios are more expensive, you can make dramatic improvements in performance without sacrificing correctness. So how does this relate to the architecture and design of some of the modern NoSQL systems? NoSQL systems can be broadly classified as master-slave sharded, or peer-to-peer sharded systems. NoSQL systems with a peer-to-peer architecture have an interesting way of handling changes. Whenever an item is changed, the client (or an intermediary) propagates the changes synchronously or asynchronously to multiple copies (for availability) of the data. Since the change can be propagated asynchronously, during some interval in time, it will be the case that some copies have received the update, and others haven’t. What happens if someone tries to read the item during this interval? The client in a peer-to-peer system will fetch the same item from multiple copies and compare them to each other. If they’re all the same, then every copy that was queried has the same (and up-to-date) value of the data item, so all’s good. If not, then the system provides a mechanism to reconcile the discrepancy and to update stale copies. So what’s the problem with this? There are two major issues: First, IT’S HORRIBLY PESSIMISTIC because, in the common case, it is unlikely that the same data item will be updated and read from different locations at around the same time! For every read operation, you have to read from multiple copies. That’s a pretty expensive, especially if the data are stored in multiple geographically separate locations and network latencies are high. Second, if the copies are not all the same, the application has to reconcile the differences and propagate the correct value to the out-dated copies. This means that the application program has to handle discrepancies in the different versions of the data item and resolve the issue (which can further add to cost and operation latency). Resolving discrepancies is only one part of the problem. What if the same data item was updated independently on two different nodes (copies)? In that case, due to the asynchronous nature of change propagation, you might land up with different versions of the data item in different copies. In this case, the application program also has to resolve conflicts and then propagate the correct value to the copies that are out-dated or have incorrect versions. This can get really complicated. My hunch is that there are many peer-to-peer-based applications that don’t handle this correctly, and worse, don’t even know it. Imagine have 100s of millions of records in your database – how can you tell whether a particular data item is incorrect or out of date? And what price are you willing to pay for ensuring that the data can be trusted? Multiple network messages per read request? Discrepancy and conflict resolution logic in the application, and potentially, additional messages? All this overhead, when all you were trying to do was to read a data item. Wouldn’t it be simpler to avoid this problem in the first place? Master-slave architectures like the Oracle NoSQL Database handles this very elegantly. A change to a data item is always sent to the master copy. Consequently, the master copy always has the most current and authoritative version of the data item. The master is also responsible for propagating the change to the other copies (for availability and read scalability). Client drivers are aware of master copies and replicas, and client drivers are also aware of the “currency” of a replica. In other words, each NoSQL Database client knows how stale a replica is. This vastly simplifies the job of the application developer. If the application needs the most current version of the data item, the client driver will automatically route the request to the master copy. If the application is willing to tolerate some staleness of data (e.g. a version that is no more than 1 second out of date), the client can easily determine which replica (or set of replicas) can satisfy the request, and route the request to the most efficient copy. This results in a dramatic simplification in application logic and also minimizes network requests (the driver will only send the request to exactl the right replica, not many). So, back to my original point. A well designed and well architected system minimizes or eliminates unnecessary overhead and avoids pessimistic algorithms wherever possible in order to deliver a highly efficient and high performance system. If you’ve every programmed an Oracle NoSQL Database application, you’ll know the difference! /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin-top:0in; mso-para-margin-right:0in; mso-para-margin-bottom:10.0pt; mso-para-margin-left:0in; line-height:115%; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin;}

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  • SQL Saturday #323 - Paris

    On September 13, 2014 the French SQL Server Community (GUSS) will be holding a SQL Saturday conference. The event is free to attend, with 4 paid-for pre-conference sessions available. Register while space is available. FREE eBook – "45 Database Performance Tips for Developers"Improve your database performance with 45 tips from SQL Server MVPs and industry experts. Get the eBook here.

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