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  • How to figure the read/write ratio in Sql Server?

    - by Bill Paetzke
    How can I query the read/write ratio in Sql Server 2005? Are there any caveats I should be aware of? Perhaps it can be found in a DMV query, a standard report, a custom report (i.e the Performance Dashboard), or examining a Sql Profiler trace. I'm not sure exactly. Why do I care? I'm taking time to improve the performance of my web app's data layer. It deals with millions of records and thousands of users. One of the points I'm examining is database concurrency. Sql Server uses pessimistic concurrency by default--good for a write-heavy app. If my app is read-heavy, I might switch it to optimistic concurrency (isolation level: read uncommitted snapshot) like Jeff Atwood did with StackOverflow.

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  • How to avoid StaleObjectStateException when transaction updates thousands of entities?

    - by ThinkFloyd
    We are using Hibernate 3.6.0.Final with JPA 2 and Spring 3.0.5 for a large scale enterprise application running on tomcat 7 and MySQL 5.5. Most of the transactions in application, lives for less than a second and update 5-10 entities but in some use cases we need to update more than 10-20K entities in single transaction, which takes few minutes and hence more than 70% of times such transaction fails with StaleObjectStateException because some of those entities got updated by some other transaction. We generally maintain version column in all tables and in case of StaleObjectStateException we generally retry but since these longs transactions are anyways very long so if we keep on retrying then also I am not very sure that we'll be able to escape StaleObjectStateException. Also lot of activities keep updating these entities in busy hours so we cannot go with pessimistic approach because it can potentially halt many activities in system. Please suggest how to fix such long transaction issue because we cannot spawn thousands of independent and small transactions because we cannot afford messed up data in case of some failed & some successful transactions.

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  • Are we ready for the Cloud computing era?

    - by andrewkatumba
    Normal 0 false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4 /* 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;} "Elite?" developer circles are abuzz with the notion of Cloud computing . The increasing bandwidth, the desire for faster and leaner operations and ofcourse the need for outsourcing non core it related business requirements e.g wordprocessing, spreadsheets, data backups. In strolls Chrome OS (am sure other similar OSes will join with their own wagons for us to jump on), offering just that, internet based services(more like a repository of), quick efficient and "reliable" and for the most part cheap and often time even free! And we all go rhapsodic!  It boils down to the age old dilemma, "if the cops are so busy protecting us then who will protect them" (even the folks back at Hollywood keep us reminded)! Who is going to ensure that these internet based services do not go down(either intentionally or by some malicious third party) leading to a multinational colossal disaster .At the risk of sounding pessimistic,  IT IS NOT AN ISSUE OF TRUST, this is but a mere case of Murphy's Law!  What then? Should the "cloud" be trusted to this extent at this time?  This is an era where challenges are rapidly solved with lightning promptness to "beat the competition", my hope is that our solutions are not just creating problems that we may not be able to solve!  Keeping my ear on the Ground.

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  • Intel Wireless 4965AGN not achieving N throughput when connected to an Airport Express N network

    - by BenA
    I have an Intel Wireless WiFi Link 4965AGN adaptor in my laptop (HP Pavillion dv2000 series) which is connecting to a 5Ghz-only 802.11n network provided by an Apple Airport Express. The network is using WPA2 encryption. My desktop is also connected the Airport, via a Linksys WUSB600N USB adaptor. Both are running with the latest drivers, and the Airport is running the latest firmware. The Airport is also configured to use wide channels. The problem I have is that I never get throughput above 4MB/s when transferring files between the two machines. Even a pessimistic calculation shows a 270Mbps network as being capable of transfer rates at well above 10MB/s. I'm pretty sure I've isolated the issue to being the Intel adaptor, as wiring the desktop to the AP, and using the Linksys adaptor on the laptop immediately yielded speeds limited by the 100MB/s ethernet connection. I know that 802.11n is still a draft standard, and so mixing kit from different manufacturers can easily lead to poor results, but I was just wondering if anybody else out there has had success with this Intel adaptor on an N network? Or even better, connecting it to an Airport Express? Can anybody give me any advice on how to troubleshoot this issue? I should also mention that the Airport Express doesn't allow you to manually specify channels when running in N mode, and that I've been able to rule out interference from other Wireless LANs by scanning. There aren't any other 5GHz networks in my area. All ideas welcome! Update: A while later, I've just updated to the most recent drivers for both the Intel chip in the laptop, and the USB adaptor. Unfortunately this hasn't improved things :(. If anybody has any advice it would be be gratefully received.

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  • How should I handle persistence in a Java MUD? OptimisticLockException handling

    - by Chase
    I'm re-implementing a old BBS MUD game in Java with permission from the original developers. Currently I'm using Java EE 6 with EJB Session facades for the game logic and JPA for the persistence. A big reason I picked session beans is JTA. I'm more experienced with web apps in which if you get an OptimisticLockException you just catch it and tell the user their data is stale and they need to re-apply/re-submit. Responding with "try again" all the time in a multi-user game would make for a horrible experience. Given that I'd expect several people to be targeting a single monster during a fight I think the chance of an OptimisticLockException would be high. My view code, the part presenting a telnet CLI, is the EJB client. Should I be catching the PersistenceExceptions and TransactionRolledbackLocalExceptions and just retrying? How do you decide when to stop? Should I switch to pessimistic locking? Is persisting after every user command overkill? Should I be loading the entire world in RAM and dumping the state every couple of minutes? Do I make my session facade a EJB 3.1 singleton which would function as a choke point and therefore eliminating the need to do any type of JPA locking? EJB 3.1 singletons function as a multiple reader/single writer design (you annotate the methods as readers and writers). Basically, what is the best design and java persistence API for highly concurrent data changes in an application where it is not acceptable to present resubmit/retry prompts to the user?

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  • Correct way to generate order numbers in SQL Server

    - by Anton Gogolev
    This question certainly applies to a much broader scope, but here it is. I have a basic ecommerce app, where users can, naturally enough, place orders. Said orders need to have a unique number, which I'm trying to generate right now. Each order is Vendor-specific. Basically, I have an OrderNumberInfo (VendorID, OrderNumber) table. Now whenever a customer places an order I need to increment OrderNumber for a particuar Vendor and return that value. Naturally, I don't want other processes to interfere with me, so I need to exclusively lock this row somehow: begin tranaction declare @n int select @n = OrderNumber from OrderNumberInfo where VendorID = @vendorID update OrderNumberInfo set OrderNumber = @n + 1 where OrderNumber = @n and VendorID = @vendorID commit transaction Now, I've read about select ... with (updlock rowlock), pessimistic locking, etc., but just cannot fit all this in a coherent picture: How do these hints play with SQL Server 2008s' snapshot isolation? Do they perform row-level, page-level or even table-level locks? How does this tolerate multiple users trying to generate numbers for a single Vendor? What isolation levels are appropriate here? And generally - what is the way to do such things?

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  • World Economic Crisis. IT prospects

    - by Andrew Florko
    There was alike question in 2008, 2 years passed. Please, share your expectations about IT market and employment in the next year or two (or so far you can predict). IMHO Russia (my native country) fully met Crisis in spring, 2008. Stock markets shrank 3(!) times during half a year. Many developers were fired those days but I suppose just because business was shocked and freezed some projects. Developers expected +20% salary growth per year in 2004-2007 (Developer salary in Moscow was about 2-3K$ in early 2008). Then there was 30% (very subjective) salary cut-off in 2008 and salaries were frozen till 2009. Now things are slowly coming back to 2008. Looking in the future I expect pessimistic scenario and another crash. Our economic depends more and more on oil & gas every year. IT that serves industry will be shrinked because we can't compete to China in real production. Due to high currency board (rubble is strong compared to dollar) we can't rely on offshore programming. Our officials are concerned on innovative economic breakthrough but it's an ordinary budget money assignemtn in practice. I don't believe in innovations either because who require innovations if you have debts and tomorrow is vapor?

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  • How to lock a transaction for reading a row and then inserting in Hibernate?

    - by at
    I have a table with a name and a name_count. So when I insert a new record, I first check what the maximum name_count is for that name. I then insert the record with that maximum + 1. Works great... except with mysql 5.1 and hibernate 3.5, by default the reads don't respect transaction boundaries. 2 of these inserts for the same name could happen at the same time and end up with the same name_count, which completely screws my application! Unfortunately, there are some specific situations where the above is actually fairly common. So what do I do? I assume I can do a pessimistic lock where any row I read is locked for further reading until I commit or roll-back my transaction. Or I can do an optimistic lock with a version column that automatically keeps trying until there are no conflicts? What's the best approach for my situation and how do I specify it in Hibernate 3.5 and mysql 5.1? The above table is massive and accessed frequently.

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  • Changing the sequencing strategy for File/Ftp Adapter

    - by [email protected]
    The File/Ftp Adapter allows the user to configure the outbound write to use a sequence number. For example, if I choose address-data_%SEQ%.txt as the FileNamingConvention, then all my files would be generated as address-data_1.txt, address-data_2.txt,...and so on. But, where does this sequence number come from? The answer lies in the "control directory" for the particular adapter project(or scenario). In general, for every project that use the File or Ftp Adapter, a unique directory is created for book keeping purposes. And since this control directory is required to be unique, the adapter uses a digest to make sure that no two control directories are the same. For example, for my FlatStructure sample, the control information for my project would go under FMW_HOME/user_projects/domains/soainfra/fileftp/controlFiles/[DIGEST]/outbound where the value of DIGEST would differ from one project to another. If you look under this directory, you will see a file control_ob.properties and this is where the sequence number is maintained. Please note that the sequence number is maintained in binary form and you hence you might need a hex editor to view its content. You will also see another zero byte file, SEQ_nnn, but, ignore that for now. We'll get to it some other time. For now, please remember that this extra file is maintained as a backup. One of the challenges faced by the adapter runtime is to guard all writes to the control files so no two threads inadverently try to update them at the same time. And, it does so with the help of a "Mutex". For now, please remember that the mutex comes in different flavors: In-memory DB-based Coherence-based User-defined Again, we will talk about these mutexes some other time. Please note that there might be scenarios, particularly under heavy load, where the mutex might become a bottleneck. The adapter, however,  allows you to change the configuration so that the adapter sequence value comes from a database sequence or a stored procedure and in such situation, the mutex is acually by-passed and thereby resulting in better throughputs. In later releases, the behavior of the adapter would be defaulted to use a db-sequence.  The simplest way to achieve this is by switching your JNDI for the outbound JCA file to use "eis/HAFileAdapter" as shown   But, what does this do? Internally, the adapter runtime creates a sequence on the oracle database. For example, if you do a "select * from user_sequences" in your soa-infra schema, you will see a new sequence being created with name as SEQ_<GUID>__ where the GUID will differ from one project to another. However, if you want to use your own sequence, then it would require you to add a new property to your JCA file called SequenceName as shown below. Please note that you will need to create this sequence on your soainfra schema beforehand.     But, what if we use DB2 or MSSQL Server as the dehydration support? DB2 supports sequences natively but MSSQL Server does not. So, the adapter runtime uses a natively generated sequence for DB2, but, for MSSQL server, the adapter relies on a stored procedure that ships with the product. If you wish to achieve the same result for SOA Suite running DB2 as the dehydration store, simply change your connection factory JNDI name in the JCA file to eis/HAFileAdapterDB2 and for MSSQL, please use eis/HAFileAdapterMSSQL. And, if you wish to use a stored procedure other than the one that ships with the product, you will need to rely on binding properties to override the adapter behavior. Particularly, you will need to instruct the adapter that you wish to use a stored procedure as shown:       Please note that if you're using the File/Ftp Adapter in Append mode, then the adapter runtime degrades the mutex to use pessimistic locks as we don't want writers from different nodes to append to the same file at the same time.                    

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  • Michael Crump&rsquo;s notes for 70-563 PRO &ndash; Designing and Developing Windows Applications usi

    - by mbcrump
    TIME TO GO PRO! This is my notes for 70-563 PRO – Designing and Developing Windows Applications using .NET Framework 3.5 I created it using several resources (various certification web sites, msdn, official ms 70-548 book). The reason that I created this review is because a) I am taking the exam. b) MS did not create a book for this exam. Use the(MS 70-548)book. c) To make sure I am familiar with each before the exam. I hope that it provides a good start for your own notes. I hope that someone finds this useful. At least, it will give you a starting point of what to expect to know on the PRO exam. Also, for those wondering, the PRO exam does contains very little code. It is basically all theory. 1. Validation Controls – How to prevent users from entering invalid data on forms. (MaskedTextBox control and RegEx) 2. ServiceController – used to start and control the behavior of existing services. 3. User Feedback (know winforms Status Bar, Tool Tips, Color, Error Provider, Context-Sensitive and Accessibility) 4. Specific (derived) exceptions must be handled before general (base class) exceptions. By moving the exception handling for the base type Exception to after exception handling of ArgumentNullException, all ArgumentNullException thrown by the Helper method will be caught and logged correctly. 5. A heartbeat method is a method exposed by a Web service that allows external applications to check on the status of the service. 6. New users must master key tasks quickly. Giving these tasks context and appropriate detail will help. However, advanced users will demand quicker paths. Shortcuts, accelerators, or toolbar buttons will speed things along for the advanced user. 7. MSBuild uses project files to instruct the build engine what to build and how to build it. MSBuild project files are XML files that adhere to the MSBuild XML schema. The MSBuild project files contain complete file, build action, and dependency information for each individual projects. 8. Evaluating whether or not to fix a bug involves a triage process. You must identify the bug's impact, set the priority, categorize it, and assign a developer. Many times the person doing the triage work will assign the bug to a developer for further investigation. In fact, the workflow for the bug work item inside of Team System supports this step. Developers are often asked to assess the impact of a given bug. This assessment helps the person doing the triage make a decision on how to proceed. When assessing the impact of a bug, you should consider time and resources to fix it, bug risk, and impacts of the bug. 9. In large projects it is generally impossible and unfeasible to fix all bugs because of the impact on schedule and budget. 10. Code reviews should be conducted by a technical lead or a technical peer. 11. Testing Applications 12. WCF Services – application state 13. SQL Server 2005 / 2008 Express Edition – reliable storage of data / Microsoft SQL Server 3.5 Compact Database– used for client computers to retrieve and save data from a shared location. 14. SQL Server 2008 Compact Edition – used for minimum possible memory and can synchronize data with a corporate SQL Server 2008 Database. Supports offline user and minimum dependency on external components. 15. MDI and SDI Forms (specifically IsMDIContainer) 16. GUID – in the case of data warehousing, it is important to define unique keys. 17. Encrypting / Security Data 18. Understanding of Isolated Storage/Proper location to store items 19. LINQ to SQL 20. Multithreaded access 21. ADO.NET Entity Framework model 22. Marshal.ReleaseComObject 23. Common User Interface Layout (ComboBox, ListBox, Listview, MaskedTextBox, TextBox, RichTextBox, SplitContainer, TableLayoutPanel, TabControl) 24. DataSets Class - http://msdn.microsoft.com/en-us/library/system.data.dataset%28VS.71%29.aspx 25. SQL Server 2008 Reporting Services (SSRS) 26. SystemIcons.Shield (Vista UAC) 27. Leverging stored procedures to perform data manipulation for a database schema that can change. 28. DataContext 29. Microsoft Windows Installer Packages, ClickOnce(bootstrapping features), XCopy. 30. Client Application Services – will authenticate users by using the same data source as a ASP.NET web application. 31. SQL Server 2008 Caching 32. StringBuilder 33. Accessibility Guidelines for Windows Applications http://msdn.microsoft.com/en-us/library/ms228004.aspx 34. Logging erros 35. Testing performance related issues. 36. Role Based Security, GenericIdentity and GenericPrincipal 37. System.Net.CookieContainer will store session data for webapps (see isolated storage for winforms) 38. .NET CLR Profiler tool will identify objects that cause performance issues. 39. ADO.NET Synchronization (SyncGroup) 40. Globalization - CultureInfo 41. IDisposable Interface- reports on several questions relating to this. 42. Adding timestamps to determine whether data has changed or not. 43. Converting applications to .NET Framework 3.5 44. MicrosoftReportViewer 45. Composite Controls 46. Windows Vista KNOWN folders. 47. Microsoft Sync Framework 48. TypeConverter -Provides a unified way of converting types of values to other types, as well as for accessing standard values and sub properties. http://msdn.microsoft.com/en-us/library/system.componentmodel.typeconverter.aspx 49. Concurrency control mechanisms The main categories of concurrency control mechanisms are: Optimistic - Delay the checking of whether a transaction meets the isolation rules (e.g., serializability and recoverability) until its end, without blocking any of its (read, write) operations, and then abort a transaction, if the desired rules are violated. Pessimistic - Block operations of a transaction, if they may cause violation of the rules. Semi-optimistic - Block operations in some situations, and do not block in other situations, while delaying rules checking to transaction's end, as done with optimistic. 50. AutoResetEvent 51. Microsoft Messaging Queue (MSMQ) 4.0 52. Bulk imports 53. KeyDown event of controls 54. WPF UI components 55. UI process layer 56. GAC (installing, removing and queuing) 57. Use a local database cache to reduce the network bandwidth used by applications. 58. Sound can easily be annoying and distracting to users, so use it judiciously. Always give users the option to turn sound off. Because a user might have sound off, never convey important information through sound alone.

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  • Evidence-Based-Scheduling - are estimations only as accurate as the work-plan they're based on?

    - by Assaf Lavie
    I've been using FogBugz's Evidence Based Scheduling (for the uninitiated, Joel explains) for a while now and there's an inherent problem I can't seem to work around. The system is good at telling me the probability that a given project will be delivered at some date, given the detailed list of tasks that comprise the project. However, it does not take into account the fact that during development additional tasks always pop up. Now, there's the garbage-can approach of creating a generic task/scheduled-item for "last minute hacks" or "integration tasks", or what have you, but that clearly goes against the idea of aggregating the estimates of many small cases. It's often the case that during the development stage of a project you realize that there's a whole area your planning didn't cover, because, well, that's the nature of developing stuff that hasn't been developed before. So now your ~3 month project may very well turn into a 6 month project, but not because your estimations were off (you could be the best estimator in the world, for those task the comprised your initial work plan); rather because you ended up adding a whole bunch of new tasks that weren't there to begin with. EBS doesn't help you with that. It could, theoretically (I guess). It could, perhaps, measure the amount of work you add to a project over time and take that into consideration when estimating the time remaining on a given project. Just a thought. In other words, EBS works on a task basis, but not on a project/release basis - but the latter is what's important. It's what your boss typically cares about - delivery date, not the time it takes to finish each task along the way, and not the time it would have taken, if your planning was perfect. So the question is (yes, there's a question here, don't close it): What's your methodology when it comes to using EBS in FogBugz and how do you solve the problem above, which seems to be a main cause of schedule delays and mispredictions? Edit Some more thoughts after reading a few answers: If it comes down to having to choose which delivery date you're comfortable presenting to your higher-ups by squinting at the delivery-probability graph and choosing 80%, or 95%, or 60% (based on what, exactly?) then we've resorted to plain old buffering/factoring of our estimates. In which case, couldn't we have skipped the meticulous case by case hour-sized estimation effort step? By forcing ourselves to break down tasks that take more than a day into smaller chunks of work haven't we just deluded ourselves into thinking our planning is as tight and thorough as it could be? People may be consistently bad estimators that do not even learn from their past mistakes. In that respect, having an EBS system is certainly better than not having one. But what can we do about the fact that we're not that good in planning as well? I'm not sure it's a problem that can be solved by a similar system. Our estimates are wrong because of tendencies to be overly optimistic/pessimistic about certain tasks, and because of neglect to account for systematic delays (e.g. sick days, major bug crisis) - and usually not because we lack knowledge about the work that needs to be done. Our planning, on the other hand, is often incomplete because we simply don't have enough knowledge in this early stage; and I don't see how an EBS-like system could fill that gap. So we're back to methodology. We need to find a way to accommodate bad or incomplete work plans that's better than voodoo-multiplication.

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  • SQL SERVER – Weekly Series – Memory Lane – #037

    - by Pinal Dave
    Here is the list of selected articles of SQLAuthority.com across all these years. Instead of just listing all the articles I have selected a few of my most favorite articles and have listed them here with additional notes below it. Let me know which one of the following is your favorite article from memory lane. 2007 Convert Text to Numbers (Integer) – CAST and CONVERT If table column is VARCHAR and has all the numeric values in it, it can be retrieved as Integer using CAST or CONVERT function. List All Stored Procedure Modified in Last N Days If SQL Server suddenly start behaving in un-expectable behavior and if stored procedure were changed recently, following script can be used to check recently modified stored procedure. If a stored procedure was created but never modified afterwards modified date and create a date for that stored procedure are same. Count Duplicate Records – Rows Validate Field For DATE datatype using function ISDATE() We always checked DATETIME field for incorrect data type. One of the user input date as 30/2/2007. The date was sucessfully inserted in the temp table but while inserting from temp table to final table it crashed with error. We had now task to validate incorrect date value before we insert in final table. Jr. Developer asked me how can he do that? We check for incorrect data type (varchar, int, NULL) but this is incorrect date value. Regular expression works fine with them because of mm/dd/yyyy format. 2008 Find Space Used For Any Particular Table It is very simple to find out the space used by any table in the database. Two Convenient Features Inline Assignment – Inline Operations Here is the script which does both – Inline Assignment and Inline Operation DECLARE @idx INT = 0 SET @idx+=1 SELECT @idx Introduction to SPARSE Columns SPARSE column are better at managing NULL and ZERO values in SQL Server. It does not take any space in database at all. If column is created with SPARSE clause with it and it contains ZERO or NULL it will be take lesser space then regular column (without SPARSE clause). SP_CONFIGURE – Displays or Changes Global Configuration Settings If advanced settings are not enabled at configuration level SQL Server will not let user change the advanced features on server. Authorized user can turn on or turn off advance settings. 2009 Standby Servers and Types of Standby Servers Standby Server is a type of server that can be brought online in a situation when Primary Server goes offline and application needs continuous (high) availability of the server. There is always a need to set up a mechanism where data and objects from primary server are moved to secondary (standby) server. BLOB – Pointer to Image, Image in Database, FILESTREAM Storage When it comes to storing images in database there are two common methods. I had previously blogged about the same subject on my visit to Toronto. With SQL Server 2008, we have a new method of FILESTREAM storage. However, the answer on when to use FILESTREAM and when to use other methods is still vague in community. 2010 Upper Case Shortcut SQL Server Management Studio I select the word and hit CTRL+SHIFT+U and it SSMS immediately changes the case of the selected word. Similar way if one want to convert cases to lower case, another short cut CTRL+SHIFT+L is also available. The Self Join – Inner Join and Outer Join Self Join has always been a noteworthy case. It is interesting to ask questions about self join in a room full of developers. I often ask – if there are three kinds of joins, i.e.- Inner Join, Outer Join and Cross Join; what type of join is Self Join? The usual answer is that it is an Inner Join. However, the reality is very different. Parallelism – Row per Processor – Row per Thread – Thread 0  If you look carefully in the Properties window or XML Plan, there is “Thread 0?. What does this “Thread 0” indicate? Well find out from the blog post. How do I Learn and How do I Teach The blog post has raised three very interesting questions. How do you learn? How do you teach? What are you learning or teaching? Let me try to answer the same. 2011 SQL SERVER – Interview Questions and Answers – Frequently Asked Questions – Day 7 of 31 What are Different Types of Locks? What are Pessimistic Lock and Optimistic Lock? When is the use of UPDATE_STATISTICS command? What is the Difference between a HAVING clause and a WHERE clause? What is Connection Pooling and why it is Used? What are the Properties and Different Types of Sub-Queries? What are the Authentication Modes in SQL Server? How can it be Changed? SQL SERVER – Interview Questions and Answers – Frequently Asked Questions – Day 8 of 31 Which Command using Query Analyzer will give you the Version of SQL Server and Operating System? What is an SQL Server Agent? Can a Stored Procedure call itself or a Recursive Stored Procedure? How many levels of SP nesting is possible? What is Log Shipping? Name 3 ways to get an Accurate Count of the Number of Records in a Table? What does it mean to have QUOTED_IDENTIFIER ON? What are the Implications of having it OFF? What is the Difference between a Local and a Global Temporary Table? What is the STUFF Function and How Does it Differ from the REPLACE Function? What is PRIMARY KEY? What is UNIQUE KEY Constraint? What is FOREIGN KEY? SQL SERVER – Interview Questions and Answers – Frequently Asked Questions – Day 9 of 31 What is CHECK Constraint? What is NOT NULL Constraint? What is the difference between UNION and UNION ALL? What is B-Tree? How to get @@ERROR and @@ROWCOUNT at the Same Time? What is a Scheduled Job or What is a Scheduled Task? What are the Advantages of Using Stored Procedures? What is a Table Called, if it has neither Cluster nor Non-cluster Index? What is it Used for? Can SQL Servers Linked to other Servers like Oracle? What is BCP? When is it Used? SQL SERVER – Interview Questions and Answers – Frequently Asked Questions – Day 10 of 31 What Command do we Use to Rename a db, a Table and a Column? What are sp_configure Commands and SET Commands? How to Implement One-to-One, One-to-Many and Many-to-Many Relationships while Designing Tables? What is Difference between Commit and Rollback when Used in Transactions? What is an Execution Plan? When would you Use it? How would you View the Execution Plan? SQL SERVER – Interview Questions and Answers – Frequently Asked Questions – Day 11 of 31 What is Difference between Table Aliases and Column Aliases? Do they Affect Performance? What is the difference between CHAR and VARCHAR Datatypes? What is the Difference between VARCHAR and VARCHAR(MAX) Datatypes? What is the Difference between VARCHAR and NVARCHAR datatypes? Which are the Important Points to Note when Multilanguage Data is Stored in a Table? How to Optimize Stored Procedure Optimization? What is SQL Injection? How to Protect Against SQL Injection Attack? How to Find Out the List Schema Name and Table Name for the Database? What is CHECKPOINT Process in the SQL Server? SQL SERVER – Interview Questions and Answers – Frequently Asked Questions – Day 12 of 31 How does Using a Separate Hard Drive for Several Database Objects Improves Performance Right Away? How to Find the List of Fixed Hard Drive and Free Space on Server? Why can there be only one Clustered Index and not more than one? What is Difference between Line Feed (\n) and Carriage Return (\r)? Is It Possible to have Clustered Index on Separate Drive From Original Table Location? What is a Hint? How to Delete Duplicate Rows? Why the Trigger Fires Multiple Times in Single Login? 2012 CTRL+SHIFT+] Shortcut to Select Code Between Two Parenthesis Shortcut key is CTRL+SHIFT+]. This key can be very useful when dealing with multiple subqueries, CTE or query with multiple parentheses. When exercised this shortcut key it selects T-SQL code between two parentheses. Monday Morning Puzzle – Query Returns Results Sometimes but Not Always I am beginner with SQL Server. I have one query, it sometime returns a result and sometime it does not return me the result. Where should I start looking for a solution and what kind of information I should send to you so you can help me with solving. I have no clue, please guide me. Remove Debug Button in SSMS – SQL in Sixty Seconds #020 – Video Effect of Case Sensitive Collation on Resultset Collation is a very interesting concept but I quite often see it is heavily neglected. I have seen developer and DBA looking for a workaround to fix collation error rather than understanding if the side effect of the workaround. Switch Between Two Parenthesis using Shortcut CTRL+] Earlier this week I wrote a blog post about CTRL+SHIFT+] Shortcut to Select Code Between Two Parenthesis, I received quite a lot of positive feedback from readers. If you are a regular reader of the blog post, you must be aware that I appreciate the learning shared by readers. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: Memory Lane, PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology

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