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  • Exception and Inheritance in JAVA

    - by user1759950
    Suppose we have this problem public class Father{ public void method1(){...} } public class Child1 extends Father{ public void method1() throws Exception{ super.method1(); ... } } Child1 extends Father and override method1 but given implementation Child1.method1 now throws a exception, this wont compile as override method can't throw new exceptions. What is the best solution? Propagate the required exception to the Father.. to me this is against encapsulation, inheritance and general OOP ( the father potentially throw and exception that will never happen ) Use a RuntimeException instead? This solution wont propagate the Exception to the father but I read In Oracle docs and others sources states class of exceptions should be used when "Client code cannot do anything" this is not that case, this exception will b useful to recover blablabla ( why is wrong to use RuntimeException instead? ) Other.. thanks, Federico

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  • What is the most "database independent" way of creating a variable length text field in a database

    - by Thibaut Colar
    I want to create a text field in the database, with no specific size (it will store text of length unknown in some case) - the particular text are serialized simple object (~ JSON) What is the most database independent way to do this : - a varchar with no size specified (don't think all db support this) - a 'text' field, this seems to be common, but I don't believe it's a standard - a blob or other object of that kind ? - a varchar of a a very large size (that's inefficient and wastes disk space probably) - Other ? I'm using JDBC, but I'd like to use something that is supported in most DB (oracle, mysql, postgresql, derby, HSQL, H2 etc...) Thanks.

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  • Java Or C++ Or What???

    - by Kronass
    Hi, My friends and I are starting a new project and we are shifting from windows to linux (for some reasons) and all of us are .Net background. for the new platform I decided to go with Java since many parts are similar with .Net but my friend is insisting on C++ saying it is much faster very mature and working with it will not effect on the productivity and development speed. The project that we will work on it will have threading, extensive string and datetime manipulation, some socket programing and of-course work with RDBMS (MySql Or Postgre not decided yet). I have some fears with java since oracle acquired sun and these people will do anything to make money out of it. some have advised in python and ruby and I like python but don't know should I make it the default language in this project. the project is not web application and we will make services and executables. what do you think, if you have other opinion you very welcome. Hint: Mono is not an option

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  • Why SQL Server Express 2008 install requires Visual Studio 2008 in checklist ?

    - by asksuperuser
    When installing SQL Server Express Edition 2008, checklist says "Previous version of Visual Studio 2008" and asked me to upgrade to sp1. Unfortunately sp1 for some reason refuses to install on my brand new pc (Windows 7). So why can't I just bypass this ? Why would SQL Server Express needs VS2008 to install that's insane. SQL Server install used to be as easy as 123, now it has become a nightmare like installing Oracle. Will I have to go back to Windows XP ?

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  • Database Optimization techniques for amateurs.

    - by Zombies
    Can we get a list of basic optimization techniques going (anything from modeling to querying, creating indexes, views to query optimization). It would be nice to have a list of these, one technique per answer. As a hobbyist I would find this to be very useful, thanks. And for the sake of not being too vague, let's say we are using a maintstream DB such as MySQL or Oracle, and that the DB will contain 500,000-1m or so records across ~10 tables, some with foreign key contraints, all using the most typical storage engines (eg: InnoDB for MySQL). And of course, the basics such as PKs are defined as well as FK contraints.

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  • Efficient way to update all rows in a table

    - by m_pGladiator
    Hi, I have a table with a lot of records (could be more than 500 000 or 1 000 000). I added a new column in this table and I need to fill a value for every row in the column, using the corresponding row value of another column in this table. I tried to use separate transactions for selecting every next chunk of 100 records and update the value for them, but still this takes hours to update all records in Oracle10 for example. What is the most efficient way to do this in SQL, without using some dialect-specific features, so it works everywhere (Oracle, MSSQL, MySQL, PostGre etc.)?

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  • How should I best store these files?

    - by Triton Man
    I have a set of image files, they are generally very small, between 5k and 100k. They can be any size though, upwards of 50mb but this is very rare. When these images are put into the system they are not ever modified. There is about 50 TB of these images total. They are currently chunked and stored in BLOBs in Oracle, but we want to change this since it requires special software to extract them. These images are access sometimes at a rate of over 100 requests per second among about 10 servers. I'm thinking about Hadoop or Cassandra, but I really don't know which would be best or how best to index them.

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  • JPA Bidirectional OneToMany and ManyToOne?

    - by PhoenixJon
    I'm using Oracle JDeveloper 11g Release 2. I created two tables A and B using SQL developer. Table A has a FK to table B. Using the Entities from Tables function, I created two JPA files from it. A has @ManyToOne annotation on FK. And also B has @OneToMany annotation to A. I don't want this. Can I remove this @OneToMany annotation automatically? public class A implements Serializable { ... @ManyToOne @JoinColumn(name = "FIELD_B") private B b; ... } public class B implements Serializable { ... @OneToMany(mappedBy = "B") private List<A> assetList; ... } I don't need @OneToMany mapping.

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  • How to step into the world of J2EE?

    - by Michael Lai
    I am new to J2ee. I have experience in Java core, JSP,Servlet, XML, HTML, What should i learn to step into the world of J2EE? Framework(Spring, Hibernate, Struts)? But the framework is too abstract for me.I saw lots of job post which requires frameworks, some jobs require EJB,JPA. I do not where to start. Any experts can give me hints on that? I found the tutorial of J2EE 5 published by ORACLE is not easy to understand. Too much jargon....

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  • What is the precedence of characters when sorting in MySQL, PHP, or just in general?

    - by FireCoding
    Question: Where can I find the precedence of characters when sorting in MySQL, PHP, or just in general on Linux and Windows OS? For example, everybody knows that a comes before b when performing an ascending sort on a string in MySQL. But what about other characters? Does the dollar-sign $ come before asterisk * ? Does a space come before an exclamation-mark? etc... What dictates the sort order? Does it use underlying ascii / UTF-8 values? Is it different for different technologies? Technologies to consider: Databases - MySQL / SQL / SQLite / Oracle / etc Programming languages (for string-sorting functions) - PHP / Javascript / ASP.NET / Visual C# / Python / Ruby / Objective C OS (i.e., sorting files by filename) - Windows / Linux / MacOS / iOS / Android

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  • Export from a standalone database to an embedded database.

    - by jdana
    I have a two-part application, where there is a central database that is edited, and then at certain times, the data is released and distributed as its own application. I would like to use a standalone database for the central database (MySQL, Postgres, Oracle, SQL Server, etc.) and then have a reliable export to an embedded database (probably SQLite) for distribution. What tools/processes are available for such an export, or is it a practice to be avoided? EDIT: A couple of additional pieces of information. The distributed application should be able to run without having to connect to another server (ex: your spellchecker still works even you don't have internet), and I don't want to install a full DB server for read-only access to the data.

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  • running jar file with multiple arguments in perl

    - by compiler9999
    Hi All, Im trying to run a jar file. this jar file will output multiple question in console manner, i want to eliminate the console and i need to input a value in order to proceed. e.g : A. Choose value 1 : [1] Windows [2] Unix Input : 2 B. Choose value 2 : [1] Oracle [2] DB2 Input : 1 Im trying : "java -jar program.jar < abc.txt" where abc.txt has a value of : 2 1 3 etc. but its not working its only getting the first value. please help. thanks. btw, ive also try : OPEN PIPE, "| java -jar program.jar"; open (FH, /abc.txt) print PIPE "$res"; close FH; close PIPE; Regards

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  • lookup datasource in context every time, Is it right?

    - by Srikanth Dyapa
    In my application i configured more than one datasource (for diff databases). Whenever user sends a request depends upon user category i need to look up for the respective datasource in the context and get a connection from that datasource to execute queries which are assigned to that user. Is it right way to achieve my requirement? I am using tomcat 6, struts 1.3. The databases may be oracle or mysql or both. Give me an optimized solution. Thanks in advance.

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  • Putting sql result set into JList

    - by 0vertone
    hi there. im working on my second year project and im nearly finished but ive got a problem. i have a table set up in oracle that holds user names, recipients, and messages. i wanted to make a contacts list for sendin messages that would take the user names and put them into a swing jlist but i cant figure out how. i thought maybe if i put the usernames into an array from the sql itd be easier but that didnt work. any ideas?

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  • SQL to get rows (not groups) that match an aggregate

    - by xulochavez
    Given table USER (name, city, age), what's the best way to get the user details of oldest user per city? I have seen the following example SQL used in Oracle which I think it works select name, city, age from USER, (select city as maxCity, max(age) as maxAge from USER group by city) where city=maxCity and age=maxAge So in essence: use a nested query to select the grouping key and aggregate for it, then use it as another table in the main query and join with the grouping key and the aggregate value for each key. Is this the standard SQL way of doing it? Is it any quicker than using a temporary table, or is in fact using a temporary table interanlly anyway?

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  • How to insert into data base using multi threading programming [closed]

    - by user1196650
    I am having a method and that method needs to do the following thing: It has to insert records into a database. No insert is done for the same table again. All inserts are into different tables. I need a multi threading logic which inserts the details into db using different threads. I am using oracle db and driver configuration and remaining stuff are perfect. Please help me with an efficient answer. Can anyone could provide me with a skeleton logic of the program.

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  • What you would learn. [closed]

    - by NDeveloper
    Hi, I have a little free time and would like to learn new development language/technology. I know it can be very subective, but please share with us what you would learn and why. I have about 4 years of .NET development experience mostly distributed applications. And a little more than 2 years of c/c++. There are a lot of options to choose like Google Go/F#/Python/Scala/Java/ASP.NET/Mobile App development like for Android, BB, iPhone.../DB (MS SQL, Oracle or even MongoDB or CouchDB)/any new concepts, etc... I would like to use the time for investment, so gained knowledge will be useful.

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  • SQL Authority News – Download Microsoft SQL Server 2014 Feature Pack and Microsoft SQL Server Developer’s Edition

    - by Pinal Dave
    Yesterday I attended the SQL Server Community Launch in Bangalore and presented on Performing an effective Presentation. It was a fun presentation and people very well received it. No matter on what subject, I present, I always end up talking about SQL. Here are two of the questions I had received during the event. Q1) I want to install SQL Server on my development server, where can we get it for free or at an economical price (I do not have MSDN)? A1) If you are not going to use your server in a production environment, you can just get SQL Server Developer’s Edition and you can read more about it over here. Here is another favorite question which I keep on receiving it during the event. Q2) I already have SQL Server installed on my machine, what are different feature pack should I install and where can I get them from. A2) Just download and install Microsoft SQL Server 2014 Service Pack. Here is the link for downloading it. The Microsoft SQL Server 2014 Feature Pack is a collection of stand-alone packages which provide additional value for Microsoft SQL Server. It includes tool and components for Microsoft SQL Server 2014 and add-on providers for Microsoft SQL Server 2014. Here is the list of component this product contains: Microsoft SQL Server Backup to Windows Azure Tool Microsoft SQL Server Cloud Adapter Microsoft Kerberos Configuration Manager for Microsoft SQL Server Microsoft SQL Server 2014 Semantic Language Statistics Microsoft SQL Server Data-Tier Application Framework Microsoft SQL Server 2014 Transact-SQL Language Service Microsoft Windows PowerShell Extensions for Microsoft SQL Server 2014 Microsoft SQL Server 2014 Shared Management Objects Microsoft Command Line Utilities 11 for Microsoft SQL Server Microsoft ODBC Driver 11 for Microsoft SQL Server – Windows Microsoft JDBC Driver 4.0 for Microsoft SQL Server Microsoft Drivers 3.0 for PHP for Microsoft SQL Server Microsoft SQL Server 2014 Transact-SQL ScriptDom Microsoft SQL Server 2014 Transact-SQL Compiler Service Microsoft System CLR Types for Microsoft SQL Server 2014 Microsoft SQL Server 2014 Remote Blob Store SQL RBS codeplex samples page SQL Server Remote Blob Store blogs Microsoft SQL Server Service Broker External Activator for Microsoft SQL Server 2014 Microsoft OData Source for Microsoft SQL Server 2014 Microsoft Balanced Data Distributor for Microsoft SQL Server 2014 Microsoft Change Data Capture Designer and Service for Oracle by Attunity for Microsoft SQL Server 2014 Microsoft SQL Server 2014 Master Data Service Add-in for Microsoft Excel Microsoft SQL Server StreamInsight Microsoft Connector for SAP BW for Microsoft SQL Server 2014 Microsoft SQL Server Migration Assistant Microsoft SQL Server 2014 Upgrade Advisor Microsoft OLEDB Provider for DB2 v5.0 for Microsoft SQL Server 2014 Microsoft SQL Server 2014 PowerPivot for Microsoft SharePoint 2013 Microsoft SQL Server 2014 ADOMD.NET Microsoft Analysis Services OLE DB Provider for Microsoft SQL Server 2014 Microsoft SQL Server 2014 Analysis Management Objects Microsoft SQL Server Report Builder for Microsoft SQL Server 2014 Microsoft SQL Server 2014 Reporting Services Add-in for Microsoft SharePoint Reference: Pinal Dave (http://blog.sqlauthority.com)Filed under: PostADay, SQL, SQL Authority, SQL Download, SQL Query, SQL Server, SQL Tips and Tricks, SQLAuthority News, T SQL

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  • Bug Triage

    In this blog post brain dump, I'll attempt to describe the process my team tries to follow when dealing with new bug reports (specifically, code defect reports). This is not official Microsoft policy, just the way we do things… if you do things differently and want to share, you can do so at the bottom in the comments (or on your blog).Feature Triage TeamA subset of the feature crew, the triage team (which has representations from the PM, Dev and QA disciplines), looks at all unassigned bugs at regular intervals. This can be weekly or daily (or other frequency) dependent on which part of the product cycle we are in and what the untriaged bug load looks like. They discuss each bug considering the evidence and make a decision of whether the bug goes from Not Yet Assigned to Assigned (plus the name of the DEV to fix this) or whether it goes from Active to Resolved (which means it gets assigned back to the requestor for closure or further debate if they were not present at the triage meeting). Close to critical milestones, the feature triage team needs to further justify bugs they take to additional higher-level triage teams.Bug Opened = Not Yet AssignedSomeone (typically an SDET from the QA team) creates the bug item (e.g. in TFS), ensuring they populate all the relevant fields including: Title, Description, Repro Steps (including the Actual Result at the end of the steps), attachments of code and/or screenshots, Build number that they observed the issue in, regression details if applicable, how it was found, if a test case exists or needs to be created etc. They also indicate their opinion on the Priority and Severity. The bug status is left as Not Yet Assigned."Issue" versus "Fix for issue"The solution to some bugs is easy to determine, e.g. "bug: the column name is misspelled". Obviously the fix is to correct the spelling – still, the triage team should be explicit and enter the correct spelling in the bug's Description. Note that a bad bug name here would be "bug: fix the spelling of the column" (it describes the solution, rather than the problem).Other solutions are trickier to establish, e.g. "bug: the column header is not accessible (can only be clicked on with the mouse, not reached via keyboard)". What is the correct solution here? The last thing to do is leave this undetermined and just assign it to a developer. The solution has to be entered in the description. Behind this type of a bug usually hides a spec defect or a new feature request.The person opening the bug should focus on describing the issue, rather than the solution. The person indicates what the fix is in their opinion by stating the Expected Result (immediately after stating the Actual Result). If they have a complex suggested solution, that should be split out in a separate part, but the triage team has the final say before assigning it. If the solution is lengthy/complicated to describe, the bug can be assigned to the PM. Note: the strict interpretation suggests that any bug with no clear, obvious solution is always a hole in the spec and should always go to the PM. This also ensures the spec gets updated.Not Yet Assigned - Not Yet Assigned (on someone else's plate)If the bug is observed in our feature, but the cause is actually another team, we change the Area Path (which is the way we identify teams in TFS) and leave it as Not Yet Assigned. The triage team may add more comments as appropriate including potentially changing the repro steps. In some cases, we may even resolve the bug in our area path and open a new bug in the area path of the other team.Even though there is no action on a dev on the team, the bug still needs to be tracked. One way of doing this is to implement some notification system that informs the team when the tracked bug changed status; another way is to occasionally run a global query (against all area paths) for bugs that have been opened by a member of the team and follow up with the current owners for stale bugs.Not Yet Assigned - ResolvedThis state transition can only be made by the Feature Triage Team.0. Sometimes the bug description is not clear and in that case it gets Resolved as More Information Needed, so the original requestor can provide it.After understanding what the bug item is about, the first decision is to determine whether it needs to go to a dev.1. If it is a known bug, it gets resolved as "Duplicate" and linked to the existing bug.2. If it is "By Design" it gets resolved as such, indicating that the triage team does not think this is a bug.3. If the bug does not repro on latest bits, it is resolved as "No Repro"4. The most painful: If it is decided that we cannot fix it for this release it gets resolved as "Postponed" or "Won't Fix". The former is typically due to resources and time constraints, while the latter is due to deciding that it is not important enough to consume our resources in any release (yes, not all bugs must be fixed!). For both cases, there are other factors that contribute to the decision such as: existence of a reasonable workaround, frequency we expect users to encounter the issue, dependencies on other team to offer a solution, whether it breaks a core scenario, whether it prohibits customer feedback on a major feature, is it a regression from a previous release, impact of the fix on other partner teams (e.g. User Education, User Experience, Localization/Globalization), whether this is the right fix, does the fix impact performance goals, and last but not least, severity of bug (e.g. loss of customer data, security threat, crash, hang). The bar for fixing a bug goes up as the release date approaches. The triage team becomes hardnosed about which bugs to take, while the developers are busy resolving assigned bugs thus everyone drives for Zero Bug Bounce (ZBB). ZBB is when you have 0 active bugs older than 48 hours.Not Yet Assigned - AssignedIf the bug is something we decide to fix in this release and the solution is known, then it is assigned to a DEV. This is either the developer that will do the work, or a Lead that can further assign it to one of his developer team based on a load balancing algorithm of their choosing.Sometimes, the triage team needs the dev to do some investigation work before deciding whether to take the fix; similarly, the checkin for the fix may be gated on code review by the triage team. In these cases, these instructions are provided in the comments section of the bug and when the developer is done they notify the triage team for final decision.Additionally, a Priority and Severity (from 0 to 4) has to be entered, e.g. a P0 means "drop anything you are doing and fix this now" whereas a P4 is something you get to after all P0,1,2,3 bugs are fixed.From a testing perspective, if the bug was found through ad-hoc testing or an external team, the decision is made whether test cases should be added to avoid future regressions. This is communicated to the QA team.Assigned - ResolvedWhen the developer receives the bug (they should be checking daily for new bugs on their plate looking at bugs in order of priority and from older to newer) they can send it back to triage if the information is not clear. Otherwise, they investigate the bug, setting the Sub Status to "Investigating"; if they cannot make progress, they set the Sub Status to "Blocked" and discuss this with triage or whoever else can help them get unblocked. Once they are unblocked, they set the Sub Status to "Working on Solution"; once they are code complete they send a code review request, setting the Sub Status to "Fix Available". After the iterative code review process is over and everyone is happy with the fix, the developer checks it in and changes the state of the bug from Active (and Assigned to them) to Resolved (and Assigned to someone else).The developer needs to ensure that when the status is changed to Resolved that it is assigned to a QA person. For example, maybe the PM opened the bug, but it should be a QA person that will verify the fix - the developer needs to manually change the assignee in that case. Typically the QA person will send an email to the original requestor notifying them that the fix is verified.Resolved - ??In all cases above, note that the final state was Resolved. What happens after that? The final step should be Closed. The bug is closed once the QA person verifying the fix is happy with it. If the person is not happy, then they change the state from Resolved to Active, thus sending it back to the developer. If the developer and QA person cannot reach agreement, then triage can be brought into it. An easy way to do that is change the status back to Not Yet Assigned with appropriate comments so the triage team can re-review.It is important to note that only QA can close a bug. That means that if the opener of the bug was a PM, when the bug gets resolved by the dev it may land on the PM's plate and after a quick review, the PM would re-assign to an SDET, which is the only role that can close bugs. One exception to this is if the person that filed the bug is external: in that case, we leave it Resolved and assigned to them and also send them a notification that they need to verify the fix. Another exception is if specialized developer knowledge is needed for verifying the bug fix (e.g. it was a refactoring suggestion bug typically not observable by the user) in which case it is fine to have a developer verify the fix, and ideally a different developer to the one that opened the bug.Other links on bug triageA quick search reveals that others have talked about this subject, e.g. here, here, here, here and here.Your take?If you have other best practices your team uses to deal with incoming bug reports, feel free to share in the comments below or on your blog. Comments about this post welcome at the original blog.

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  • Forbes Announcing The World’s Top 20 Billionaires

    - by Suganya
    Forbes company recently conducted a survey to figure out the world’s Billionaires list and has released it listing the top 20 names of the Billionaires. The company says that for the third time in the last three years the world has a new richest man for this year. So it means that Bill Gates was beaten up by someone else in world. Who is the new richest man in the world?   Forbes.Com announced the richest man in world and this time it is not Bill Gates. But it is Carlos Slim Helu who is into Telecom industry. Carlos lives in Mexico and he had the third richest man’s place last year. Having shown a Net worth of $ 53.5 Billion, Carlos has increased $18.5 Billion in a year. Carlos swooped on the privatization of Mexico’s national telephone service during the last decade and now has achieved the world’s first richest man. Following Carlos, in the second position is Bill Gates with the Nett worth of $53 Billion. As Bill Gates requires no great introduction, lets move on to the next place. The third place is occupied by Warren Buffett followed by Mukesh Ambani and Lakshmi Mittal in fourth and fifth places respectively. The top 20 names of world’s richest people, their occupation and the Nett worth that they hold are S.No Name Nett Worth (in $ Billion) Source of Income 1 Carlos Slim Helu 53.5 Telecom 2 Bill Gates 53 Microsoft 3 Warren Buffett 47 Investments 4 Mukesh Ambani 29 Petrochemical, Oil and Gas 5 Lakshmi Mittal 28.7 Steel 6 Lawrence Ellison 28 Oracle 7 Bernard Arnault 27.5 Luxury Goods 8 Eike Batista 27 Mining, Oil 9 Amancio Ortega 25 Fashion, Retail 10 Karl Albrecht 23.5 Supermarkets 11 Ingvar Kamprad and Family 23 IKEA 12 Christy Walton and Family 22.5 Wal-Mart 13 Stefan Persson 22.4 H & M 14 Li Ka-shing 21 Diversified 15 Jim C. Walton 20.7 Wal-Mart 16 Alice Walton 20.6 Wal-Mart 17 Liliane Bettencourt 20 L’Oreal 18 S. Robson Walton 19.8 Wal-Mart 19 Prince Alwaleed bin Talal Alsaud 19.4 Diversified 20 David Thomson and Family 19 Thomson Reuters   Source: Forbes and Image Credit : kevindooley Join us on Facebook to read all our stories right inside your Facebook news feed.

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  • SQL Server and Hyper-V Dynamic Memory Part 2

    - by SQLOS Team
    Part 1 of this series was an introduction and overview of Hyper-V Dynamic Memory. This part looks at SQL Server memory management and how the SQL engine responds to changing OS memory conditions.   Part 2: SQL Server Memory Management As with any Windows process, sqlserver.exe has a virtual address space (VAS) of 4GB on 32-bit and 8TB in 64-bit editions. Pages in its VAS are mapped to pages in physical memory when the memory is committed and referenced for the first time. The collection of VAS pages that have been recently referenced is known as the Working Set. How and when SQL Server allocates virtual memory and grows its working set depends on the memory model it uses. SQL Server supports three basic memory models:   1. Conventional Memory Model   The Conventional model is the default SQL Server memory model and has the following properties: - Dynamic - can grow or shrink its working set in response to load and external (operating system) memory conditions. - OS uses 4K pages – (not to be confused with SQL Server “pages” which are 8K regions of committed memory).- Pageable - Can be paged out to disk by the operating system.   2. Locked Page Model The locked page memory model is set when SQL Server is started with "Lock Pages in Memory" privilege*. It has the following characteristics: - Dynamic - can grow or shrink its working set in the same way as the Conventional model.- OS uses 4K pages - Non-Pageable – When memory is committed it is locked in memory, meaning that it will remain backed by physical memory and will not be paged out by the operating system. A common misconception is to interpret "locked" as non-dynamic. A SQL Server instance using the locked page memory model will grow and shrink (allocate memory and release memory) in response to changing workload and OS memory conditions in the same way as it does with the conventional model.   This is an important consideration when we look at Hyper-V Dynamic Memory – “locked” memory works perfectly well with “dynamic” memory.   * Note in “Denali” (Standard Edition and above), and in SQL 2008 R2 64-bit (Enterprise and above editions) the Lock Pages in Memory privilege is all that is required to set this model. In 2008 R2 64-Bit standard edition it also requires trace flag 845 to be set, in 2008 R2 32-bit editions it requires sp_configure 'awe enabled' 1.   3. Large Page Model The Large page model is set using trace flag 834 and potentially offers a small performance boost for systems that are configured with large pages. It is characterized by: - Static - memory is allocated at startup and does not change. - OS uses large (>2MB) pages - Non-Pageable The large page model is supported with Hyper-V Dynamic Memory (and Hyper-V also supports large pages), but you get no benefit from using Dynamic Memory with this model since SQL Server memory does not grow or shrink. The rest of this article will focus on the locked and conventional SQL Server memory models.   When does SQL Server grow? For “dynamic” configurations (Conventional and Locked memory models), the sqlservr.exe process grows – allocates and commits memory from the OS – in response to a workload. As much memory is allocated as is required to optimally run the query and buffer data for future queries, subject to limitations imposed by:   - SQL Server max server memory setting. If this configuration option is set, the buffer pool is not allowed to grow to more than this value. In SQL Server 2008 this value represents single page allocations, and in “Denali” it represents any size page allocations and also managed CLR procedure allocations.   - Memory signals from OS. The operating system sets a signal on memory resource notification objects to indicate whether it has memory available or whether it is low on available memory. If there is only 32MB free for every 4GB of memory a low memory signal is set, which continues until 64MB/4GB is free. If there is 96MB/4GB free the operating system sets a high memory signal. SQL Server only allocates memory when the high memory signal is set.   To summarize, for SQL Server to grow you need three conditions: a workload, max server memory setting higher than the current allocation, high memory signals from the OS.    When does SQL Server shrink caches? SQL Server as a rule does not like to return memory to the OS, but it will shrink its caches in response to memory pressure. Memory pressure can be divided into “internal” and “external”.   - External memory pressure occurs when the operating system is running low on memory and low memory signals are set. The SQL Server Resource Monitor checks for low memory signals approximately every 5 seconds and it will attempt to free memory until the signals stop.   To free memory SQL Server does the following: ·         Frees unused memory. ·         Notifies Memory Manager Clients to release memory o   Caches – Free unreferenced cache objects. o   Buffer pool - Based on oldest access times.   The freed memory is released back to the operating system. This process continues until the low memory resource notifications stop.    - Internal memory pressure occurs when the size of different caches and allocations increase but the SQL Server process needs to keep its total memory within a target value. For example if max server memory is set and certain caches are growing large, it will cause SQL to free memory for re-use internally, but not to release memory back to the OS. If you lower the value of max server memory you will generate internal memory pressure that will cause SQL to release memory back to the OS.    Memory pressure handling has not changed much since SQL 2005 and it was described in detail in a blog post by Slava Oks.   Note that SQL Server Express is an exception to the above behavior. Unlike other editions it does not assume it is the most important process running on the system but tries to be more “desktop” friendly. It will empty its working set after a period of inactivity.   How does SQL Server respond to changing OS memory?    In SQL Server 2005 support for Hot-Add memory was introduced. This feature, available in Enterprise and above editions, allows the server to make use of any extra physical memory that was added after SQL Server started. Being able to add physical memory when the system is running is limited to specialized hardware, but with the Hyper-V Dynamic Memory feature, when new memory is allocated to a guest virtual machine, it looks like hot-add physical memory to the guest. What this means is that thanks to the hot-add memory feature, SQL Server 2005 and higher can dynamically grow if more “physical” memory is granted to a guest VM by Hyper-V dynamic memory.   SQL Server checks OS memory every second and dynamically adjusts its “target” (based on available OS memory and max server memory) accordingly.   In “Denali” Standard Edition will also have sqlserver.exe support for hot-add memory when running virtualized (i.e. detecting and acting on Hyper-V Dynamic Memory allocations).   How does a SQL Server workload in a guest VM impact Hyper-V dynamic memory scheduling?   When a SQL workload causes the sqlserver.exe process to grow its working set, the Hyper-V memory scheduler will detect memory pressure in the guest VM and add memory to it. SQL Server will then detect the extra memory and grow according to workload demand. In our tests we have seen this feedback process cause a guest VM to grow quickly in response to SQL workload - we are still working on characterizing this ramp-up.    How does SQL Server respond when Hyper-V removes memory from a guest VM through ballooning?   If pressure from other VM's cause Hyper-V Dynamic Memory to take memory away from a VM through ballooning (allocating memory with a virtual device driver and returning it to the host OS), Windows Memory Manager will page out unlocked portions of memory and signal low resource notification events. When SQL Server detects these events it will shrink memory until the low memory notifications stop (see cache shrinking description above).    This raises another question. Can we make SQL Server release memory more readily and hence behave more "dynamically" without compromising performance? In certain circumstances where the application workload is predictable it may be possible to have a job which varies "max server memory" according to need, lowering it when the engine is inactive and raising it before a period of activity. This would have limited applicaability but it is something we're looking into.   What Memory Management changes are there in SQL Server “Denali”?   In SQL Server “Denali” (aka SQL11) the Memory Manager has been re-written to be more efficient. The main changes are summarized in this post. An important change with respect to Hyper-V Dynamic Memory support is that now the max server memory setting includes any size page allocations and managed CLR procedure allocations it now represents a closer approximation to total sqlserver.exe memory usage. This makes it easier to calculate a value for max server memory, which becomes important when configuring virtual machines to work well with Hyper-V Dynamic Memory Startup and Maximum RAM settings.   Another important change is no more AWE or hot-add support for 32-bit edition. This means if you're running a 32-bit edition of Denali you're limited to a 4GB address space and will not be able to take advantage of dynamically added OS memory that wasn't present when SQL Server started (though Hyper-V Dynamic Memory is still a supported configuration).   In part 3 we’ll develop some best practices for configuring and using SQL Server with Dynamic Memory. Originally posted at http://blogs.msdn.com/b/sqlosteam/

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  • SQLAuthority News – MS Access Database is the Way to Go – April 1st Humor

    - by pinaldave
    First of all, today is April 1- April Fool’s Day, so I have written this post for some light entertainment. My friend has just sent me an email about why a person should go for Access Database. For a short background, I used to be an MS Access user once (I will not call myself MS Access DBA), and I must say I had a good time with Database at that time. As time passed by, I moved from MS Access to SQL Server. Well, as for my friend’s email, his reasons considering MS Access usage really made me laugh. MS Access may have a few points where it totally makes sense to use it. However, in the email that I received, there was not a single reason which was valid.  In fact, I thought it is an April 1st joke- just delivered a little earlier. Let us see some of the reasons from that email. Thanks to Mahesh Bhesania for sending this email to me. MS Access comes with lots of free stuff, e.g. MS Excel MS Access is the most preferred desktop database system MS Access can import data from MS Excel and SQL Server MS Access provides a real time database MS Access has a free IDE-to-VB Script MS Access fits well in your hard drive I actually think that the above points are either incorrect beliefs of some users, or someone just wrote them to give some laughter with such inaccurate data. And, for the same reason I decided to browse the Internet and do some research on MS Access database to verify my thoughts. While searching on this subject, I found the following two interesting statements from the site: Microsoft Access Database, Why Choose It? Other software manufacturers are more likely to provide interfaces to MS Access than any other desktop database system Microsoft Access consulting rates are typically lower for Access consultants compared to Oracle or SQL Server consultants The second one is may be the worst reason for you to switch to MS Access if you are already an SQL Server consultant. With this cartoon, have you ever felt like you were one of these chickens at some point in time? I guess that the moment might have just happened before the minute we say “I guess we were on the same page?” Does this mean we are IN the same table, or ON the same table?! (I accept bad joke!) It is All Fools’ Day after all, so just laugh! If you have something funny but non-offensive to share, just  leave your comment here. Reference: Pinal Dave (http://blog.SQLAuthority.com), Cartoon source unknown. Filed under: Software Development, SQL, SQL Authority, SQL Humor, SQL Query, SQL Server, SQL Tips and Tricks, SQLAuthority News, T SQL, Technology Tagged: MS ACCESS

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  • Using linked servers, OPENROWSET and OPENQUERY

    - by BuckWoody
    SQL Server has a few mechanisms to reach out to another server (even another server type) and query data from within a Transact-SQL statement. Among them are a set of stored credentials and information (called a Linked Server), a statement that uses a linked server called called OPENQUERY, another called OPENROWSET, and one called OPENDATASOURCE. This post isn’t about those particular functions or statements – hit the links for more if you’re new to those topics. I’m actually more concerned about where I see these used than the particular method. In many cases, a Linked server isn’t another Relational Database Management System (RDMBS) like Oracle or DB2 (which is possible with a linked server), but another SQL Server. My concern is that linked servers are the new Data Transformation Services (DTS) from SQL Server 2000 – something that was designed for one purpose but which is being morphed into something much more. In the case of DTS, most of us turned that feature into a full-fledged job system. What was designed as a simple data import and export system has been pressed into service doing logic, routing and timing. And of course we all know how painful it was to move off of a complex DTS system onto SQL Server Integration Services. In the case of linked servers, what should be used as a method of running a simple query or two on another server where you have occasional connection or need a quick import of a small data set is morphing into a full federation strategy. In some cases I’ve seen a complex web of linked servers, and when credentials, names or anything else changes there are huge problems. Now don’t get me wrong – linked servers and other forms of distributing queries is a fantastic set of tools that we have to move data around. I’m just saying that when you start having lots of workarounds and when things get really complicated, you might want to step back a little and ask if there’s a better way. Are you able to tolerate some latency? Perhaps you’re able to use Service Broker. Would you like to be platform-independent on the data source? Perhaps a middle-tier might make more sense, abstracting the queries there and sending them to the proper server. Designed properly, I’ve seen these systems scale further and be more resilient than loading up on linked servers. Share this post: email it! | bookmark it! | digg it! | reddit! | kick it! | live it!

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  • Quartz.Net Writing your first Hello World Job

    - by Tarun Arora
    In this blog post I’ll be covering, 01: A few things to consider before you should schedule a Job using Quartz.Net 02: Setting up your solution to use Quartz.Net API 03: Quartz.Net configuration 04: Writing & scheduling a hello world job with Quartz.Net If you are new to Quartz.Net I would recommend going through, A brief introduction to Quartz.net Walkthrough of Installing & Testing Quartz.Net as a Windows Service A few things to consider before you should schedule a Job using Quartz.Net - An instance of the scheduler service - A trigger - And last but not the least a job For example, if I wanted to schedule a script to run on the server, I should be jotting down answers to the below questions, a. Considering there are multiple machines set up with Quartz.Net windows service, how can I choose the instance of Quartz.Net where I want my script to be run b. What will trigger the execution of the job c. How often do I want the job to run d. Do I want the job to run right away or start after a delay or may be have the job start at a specific time e. What will happen to my job if Quartz.Net windows service is reset f. Do I want multiple instances of this job to run concurrently g. Can I pass parameters to the job being executed by Quartz.Net windows service Setting up your solution to use Quartz.Net API 1. Create a new C# Console Application project and call it “HelloWorldQuartzDotNet” and add a reference to Quartz.Net.dll. I use the NuGet Package Manager to add the reference. This can be done by right clicking references and choosing Manage NuGet packages, from the Nuget Package Manager choose Online from the left panel and in the search box on the right search for Quartz.Net. Click Install on the package “Quartz” (Screen shot below). 2. Right click the project and choose Add New Item. Add a new Interface and call it ‘IScheduledJob.cs’. Mark the Interface public and add the signature for Run. Your interface should look like below. namespace HelloWorldQuartzDotNet { public interface IScheduledJob { void Run(); } }   3. Right click the project and choose Add new Item. Add a class and call it ‘Scheduled Job’. Use this class to implement the interface ‘IscheduledJob.cs’. Look at the pseudo code in the implementation of the Run method. using System; namespace HelloWorldQuartzDotNet { class ScheduledJob : IScheduledJob { public void Run() { // Get an instance of the Quartz.Net scheduler // Define the Job to be scheduled // Associate a trigger with the Job // Assign the Job to the scheduler throw new NotImplementedException(); } } }   I’ll get into the implementation in more detail, but let’s look at the minimal configuration a sample configuration file for Quartz.Net service to work. Quartz.Net configuration In the App.Config file copy the below configuration <?xml version="1.0" encoding="utf-8" ?> <configuration> <configSections> <section name="quartz" type="System.Configuration.NameValueSectionHandler, System, Version=1.0.5000.0,Culture=neutral, PublicKeyToken=b77a5c561934e089" /> </configSections> <quartz> <add key="quartz.scheduler.instanceName" value="ServerScheduler" /> <add key="quartz.threadPool.type" value="Quartz.Simpl.SimpleThreadPool, Quartz" /> <add key="quartz.threadPool.threadCount" value="10" /> <add key="quartz.threadPool.threadPriority" value="2" /> <add key="quartz.jobStore.misfireThreshold" value="60000" /> <add key="quartz.jobStore.type" value="Quartz.Simpl.RAMJobStore, Quartz" /> </quartz> </configuration>   As you can see in the configuration above, I have included the instance name of the quartz scheduler, the thread pool type, count and priority, the job store type has been defined as RAM. You have the option of configuring that to ADO.NET JOB store. More details here. Writing & scheduling a hello world job with Quartz.Net Once fully implemented the ScheduleJob.cs class should look like below. I’ll walk you through the details of the implementation… - GetScheduler() uses the name of the quartz.net and listens on localhost port 555 to try and connect to the quartz.net windows service. - Run() an attempt is made to start the scheduler in case it is in standby mode - I have defined a job “WriteHelloToConsole” (that’s the name of the job), this job belongs to the group “IT”. Think of group as a logical grouping feature. It helps you bucket jobs into groups. Quartz.Net gives you the ability to pause or delete all jobs in a group (We’ll look at that in some of the future posts). I have requested for recovery of this job in case the quartz.net service fails over to the other node in the cluster. The jobType is “HelloWorldJob”. This is the class that would be called to execute the job. More details on this below… - I have defined a trigger for my job. I have called the trigger “WriteHelloToConsole”. The Trigger works on the cron schedule “0 0/1 * 1/1 * ? *” which means fire the job once every minute. I would recommend that you look at www.cronmaker.com a free and great website to build and parse cron expressions. The trigger has a priority 1. So, if two jobs are run at the same time, this trigger will have high priority and will be run first. - Use the Job and Trigger to schedule the job. This method returns a datetime offeset. It is possible to see the next fire time for the job from this variable. using System.Collections.Specialized; using System.Configuration; using Quartz; using System; using Quartz.Impl; namespace HelloWorldQuartzDotNet { class ScheduledJob : IScheduledJob { public void Run() { // Get an instance of the Quartz.Net scheduler var schd = GetScheduler(); // Start the scheduler if its in standby if (!schd.IsStarted) schd.Start(); // Define the Job to be scheduled var job = JobBuilder.Create<HelloWorldJob>() .WithIdentity("WriteHelloToConsole", "IT") .RequestRecovery() .Build(); // Associate a trigger with the Job var trigger = (ICronTrigger)TriggerBuilder.Create() .WithIdentity("WriteHelloToConsole", "IT") .WithCronSchedule("0 0/1 * 1/1 * ? *") // visit http://www.cronmaker.com/ Queues the job every minute .WithPriority(1) .Build(); // Assign the Job to the scheduler var schedule = schd.ScheduleJob(job, trigger); Console.WriteLine("Job '{0}' scheduled for '{1}'", "", schedule.ToString("r")); } // Get an instance of the Quartz.Net scheduler private static IScheduler GetScheduler() { try { var properties = new NameValueCollection(); properties["quartz.scheduler.instanceName"] = "ServerScheduler"; // set remoting expoter properties["quartz.scheduler.proxy"] = "true"; properties["quartz.scheduler.proxy.address"] = string.Format("tcp://{0}:{1}/{2}", "localhost", "555", "QuartzScheduler"); // Get a reference to the scheduler var sf = new StdSchedulerFactory(properties); return sf.GetScheduler(); } catch (Exception ex) { Console.WriteLine("Scheduler not available: '{0}'", ex.Message); throw; } } } }   The above highlighted values have been taken from the Quartz.config file, this file is available in the Quartz.net server installation directory. Implementation of my HelloWorldJob Class below. The HelloWorldJob class gets called to execute the job “WriteHelloToConsole” using the once every minute trigger set up for this job. The HelloWorldJob is a class that implements the interface IJob. I’ll walk you through the details of the implementation… - context is passed to the method execute by the quartz.net scheduler service. This has everything you need to pull out the job, trigger specific information. - for example. I have pulled out the value of the jobKey name, the fire time and next fire time. using Quartz; using System; namespace HelloWorldQuartzDotNet { class HelloWorldJob : IJob { public void Execute(IJobExecutionContext context) { try { Console.WriteLine("Job {0} fired @ {1} next scheduled for {2}", context.JobDetail.Key, context.FireTimeUtc.Value.ToString("r"), context.NextFireTimeUtc.Value.ToString("r")); Console.WriteLine("Hello World!"); } catch (Exception ex) { Console.WriteLine("Failed: {0}", ex.Message); } } } }   I’ll add a call to call the scheduler in the Main method in Program.cs using System; using System.Threading; namespace HelloWorldQuartzDotNet { class Program { static void Main(string[] args) { try { var sj = new ScheduledJob(); sj.Run(); Thread.Sleep(10000 * 10000); } catch (Exception ex) { Console.WriteLine("Failed: {0}", ex.Message); } } } }   This was third in the series of posts on enterprise scheduling using Quartz.net, in the next post I’ll be covering how to pass parameters to the scheduled task scheduled on Quartz.net windows service. Thank you for taking the time out and reading this blog post. If you enjoyed the post, remember to subscribe to http://feeds.feedburner.com/TarunArora. Stay tuned!

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  • Learn Cloud Computing – It’s Time

    - by Ben Griswold
    Last week, I gave an in-house presentation on cloud computing.  I walked through an overview of cloud computing – characteristics (on demand, elastic, fully managed by provider), why are we interested (virtualization, distributed computing, increased access to high-speed internet, weak economy), various types (public, private, virtual private cloud) and services models (IaaS, PaaS, SaaS.)  Though numerous providers have emerged in the cloud computing space, the presentation focused on Amazon, Google and Microsoft offerings and provided an overview of their platforms, costs, data tier technologies, management and security.  One of the biggest talking points was why developers should consider the cloud as part of their deployment strategy: You only have to pay for what you consume You will be well-positioned for one time event provisioning You will reap the benefits of automated growth and scalable technologies For the record: having deployed dozens of applications on various platforms over the years, pricing tends to be the biggest customer concern.  Yes, scalability is a customer consideration, too, but it comes in distant second.  Boy do I hope you’re still reading… You may be thinking, “Cloud computing is well and good and it sounds catchy, but should I bother?  After all, it’s just another technology bundle which I’m supposed to ramp up on because it’s the latest thing, right?”  Well, my clients used to be 100% reliant upon me to find adequate hosting for them.  Now I find they are often aware of cloud services and some come to me with the “possibility” that deploying to the cloud is the best solution for them.  It’s like the patient who walks into the doctor’s office with their diagnosis and treatment already in mind thanks to the handful of Internet searches they performed earlier that day.  You know what?  The customer may be correct about the cloud. It may be a perfect fit for their app.  But maybe not…  I don’t think there’s a need to learn about every technical thing under the sun, but if you are responsible for identifying hosting solutions for your customers, it is time to get up to speed on cloud computing and the various offerings (if you haven’t already.)  Here are a few references to get you going: DZone Refcardz #82 Getting Started with Cloud Computing by Daniel Rubio Wikipedia Cloud Computing – What is it? Amazon Machine Images (AMI) Google App Engine SDK Azure SDK EC2 Spot Pricing Google App Engine Team Blog Amazon EC2 Team Blog Microsoft Azure Team Blog Amazon EC2 – Cost Calculator Google App Engine – Cost and Billing Resources Microsoft Azure – Cost Calculator Larry Ellison has stated that cloud computing has been defined as "everything that we currently do" and that it will have no effect except to "change the wording on some of our ads" Oracle launches worldwide cloud-computing tour NoSQL Movement  

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