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  • SQLAuthority News – SQL SERVER 2008 R2 Pricing

    - by pinaldave
    I was recently asked question about SQL Server 2008 pricing. I have bookmarked official site here which lists the pricing. Official site: What’s New in SQL Server 2008 R2 Editions Editions Per Processor PricingRetail Per Server Plus CAL PricingRetail Parallel Data Warehouse $57,498 Not offered via Server CAL Datacenter $57,498 Not offered via Server CAL Enterprise $28,749 $13,969 with 25 CALs Standard $7,499 $1,849 with 5 CALs However, I have [...]

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  • SQL SERVER – Solution – Puzzle – Challenge – Error While Converting Money to Decimal

    - by pinaldave
    Earlier I had posted quick puzzle and I had received wonderful response to the same. Today we will go over the solution. The puzzle was posted here: SQL SERVER – Puzzle – Challenge – Error While Converting Money to Decimal Run following code in SSMS: DECLARE @mymoney MONEY; SET @mymoney = 12345.67; SELECT CAST(@mymoney AS DECIMAL(5,2)) MoneyInt; GO Above code will give following error: Msg 8115, Level 16, State 8, Line 3 Arithmetic overflow error converting money to data type numeric. Why and what is the solution? Solution is as following: DECLARE @mymoney MONEY; SET @mymoney = 12345.67; SELECT CAST(@mymoney AS DECIMAL(7,2)) MoneyInt; GO There were more than 20 valid answers. Here is the reason. Decimal data type is defined as Decimal (Precision, Scale), in other words Decimal (Total digits, Digits after decimal point).. Precision includes Scale. So Decimal (5,2) actually means, we can have 3 digits before decimal and 2 digits after decimal. To accommodate 12345.67 one need higher precision. The correct answer would be DECIMAL (7,2) as it can hold all the seven digits. Here are the list of the experts who have got correct answer and I encourage all of you to read the same over hear. Fbncs Piyush Srivastava Dheeraj Abhishek Anil Gurjar Keval Patel Rajan Patel Himanshu Patel Anurodh Srivastava aasim abdullah Paulo R. Pereira Chintak Chhapia Scott Humphrey Alok Chandra Shahi Imran Mohammed SHIVSHANKER The very first answer was provided by Fbncs and Dheeraj had very interesting comment. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: Pinal Dave, Readers Contribution, Readers Question, SQL, SQL Authority, SQL Query, SQL Scripts, SQL Server, SQL Tips and Tricks, T SQL, Technology

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  • SQL SERVER – Guest Post – Jacob Sebastian – Filestream – Wait Types – Wait Queues – Day 22 of 28

    - by pinaldave
    Jacob Sebastian is a SQL Server MVP, Author, Speaker and Trainer. Jacob is one of the top rated expert community. Jacob wrote the book The Art of XSD – SQL Server XML Schema Collections and wrote the XML Chapter in SQL Server 2008 Bible. See his Blog | Profile. He is currently researching on the subject of Filestream and have submitted this interesting article on the very subject. What is FILESTREAM? FILESTREAM is a new feature introduced in SQL Server 2008 which provides an efficient storage and management option for BLOB data. Many applications that deal with BLOB data today stores them in the file system and stores the path to the file in the relational tables. Storing BLOB data in the file system is more efficient that storing them in the database. However, this brings up a few disadvantages as well. When the BLOB data is stored in the file system, it is hard to ensure transactional consistency between the file system data and relational data. Some applications store the BLOB data within the database to overcome the limitations mentioned earlier. This approach ensures transactional consistency between the relational data and BLOB data, but is very bad in terms of performance. FILESTREAM combines the benefits of both approaches mentioned above without the disadvantages we examined. FILESTREAM stores the BLOB data in the file system (thus takes advantage of the IO Streaming capabilities of NTFS) and ensures transactional consistency between the BLOB data in the file system and the relational data in the database. For more information on the FILESTREAM feature, visit: http://beyondrelational.com/filestream/default.aspx FILESTREAM Wait Types Since this series is on the different SQL Server wait types, let us take a look at the various wait types that are related to the FILESTREAM feature. FS_FC_RWLOCK This wait type is generated by FILESTREAM Garbage Collector. This occurs when Garbage collection is disabled prior to a backup/restore operation or when a garbage collection cycle is being executed. FS_GARBAGE_COLLECTOR_SHUTDOWN This wait type occurs when during the cleanup process of a garbage collection cycle. It indicates that that garbage collector is waiting for the cleanup tasks to be completed. FS_HEADER_RWLOCK This wait type indicates that the process is waiting for obtaining access to the FILESTREAM header file for read or write operation. The FILESTREAM header is a disk file located in the FILESTREAM data container and is named “filestream.hdr”. FS_LOGTRUNC_RWLOCK This wait type indicates that the process is trying to perform a FILESTREAM log truncation related operation. It can be either a log truncate operation or to disable log truncation prior to a backup or restore operation. FSA_FORCE_OWN_XACT This wait type occurs when a FILESTREAM file I/O operation needs to bind to the associated transaction, but the transaction is currently owned by another session. FSAGENT This wait type occurs when a FILESTREAM file I/O operation is waiting for a FILESTREAM agent resource that is being used by another file I/O operation. FSTR_CONFIG_MUTEX This wait type occurs when there is a wait for another FILESTREAM feature reconfiguration to be completed. FSTR_CONFIG_RWLOCK This wait type occurs when there is a wait to serialize access to the FILESTREAM configuration parameters. Waits and Performance System waits has got a direct relationship with the overall performance. In most cases, when waits increase the performance degrades. SQL Server documentation does not say much about how we can reduce these waits. However, following the FILESTREAM best practices will help you to improve the overall performance and reduce the wait types to a good extend. Read all the post in the Wait Types and Queue series. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, PostADay, Readers Contribution, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, SQL Wait Stats, SQL Wait Types, T SQL, Technology Tagged: Filestream

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  • SQL SERVER – Automated Type Conversion using Expressor Studio

    - by pinaldave
    Recently I had an interesting situation during my consultation project. Let me share to you how I solved the problem using Expressor Studio. Consider a situation in which you need to read a field, such as customer_identifier, from a text file and pass that field into a database table. In the source file’s metadata structure, customer_identifier is described as a string; however, in the target database table, customer_identifier is described as an integer. Legitimately, all the source values for customer_identifier are valid numbers, such as “109380”. To implement this in an ETL application, you probably would have hard-coded a type conversion function call, such as: output.customer_identifier=stringToInteger(input.customer_identifier) That wasn’t so bad, was it? For this instance, programming this hard-coded type conversion function call was relatively easy. However, hard-coding, whether type conversion code or other business rule code, almost always means that the application containing hard-coded fields, function calls, and values is: a) specific to an instance of use; b) is difficult to adapt to new situations; and c) doesn’t contain many reusable sub-parts. Therefore, in the long run, applications with hard-coded type conversion function calls don’t scale well. In addition, they increase the overall level of effort and degree of difficulty to write and maintain the ETL applications. To get around the trappings of hard-coding type conversion function calls, developers need an access to smarter typing systems. Expressor Studio product offers this feature exactly, by providing developers with a type conversion automation engine based on type abstraction. The theory behind the engine is quite simple. A user specifies abstract data fields in the engine, and then writes applications against the abstractions (whereas in most ETL software, developers develop applications against the physical model). When a Studio-built application is run, Studio’s engine automatically converts the source type to the abstracted data field’s type and converts the abstracted data field’s type to the target type. The engine can do this because it has a couple of built-in rules for type conversions. So, using the example above, a developer could specify customer_identifier as an abstract data field with a type of integer when using Expressor Studio. Upon reading the string value from the text file, Studio’s type conversion engine automatically converts the source field from the type specified in the source’s metadata structure to the abstract field’s type. At the time of writing the data value to the target database, the engine doesn’t have any work to do because the abstract data type and the target data type are just the same. Had they been different, the engine would have automatically provided the conversion. ?Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Database, Pinal Dave, SQL, SQL Authority, SQL Query, SQL Scripts, SQL Server, SQL Tips and Tricks, SQLAuthority News, T SQL, Technology Tagged: SSIS

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  • SQL SERVER – Interview Questions and Answers – Frequently Asked Questions – Introduction – Day 1 of 31

    - by pinaldave
    List of all the Interview Questions and Answers Series blogs Posts covering interview questions and answers always make for interesting reading.  Some people like the subject for their helpful hints and thought provoking subject, and others dislike these posts because they feel it is nothing more than cheating.  I’d like to discuss the pros and cons of a Question and Answer format here. Interview Questions and Answers are Helpful Just like blog posts, books, and articles, interview Question and Answer discussions are learning material.  The popular Dummy’s books or Idiots Guides are not only for “dummies,” but can help everyone relearn the fundamentals.  Question and Answer discussions can serve the same purpose.  You could call this SQL Server Fundamentals or SQL Server 101. I have administrated hundreds of interviews during my career and I have noticed that sometimes an interviewee with several years of experience lacks an understanding of the fundamentals.  These individuals have been in the industry for so long, usually working on a very specific project, that the ABCs of the business have slipped their mind. Or, when a college graduate is looking to get into the industry, he is not expected to have experience since he is just graduated. However, the new grad is expected to have an understanding of fundamentals and theory.  Sometimes after the stress of final exams and graduation, it can be difficult to remember the correct answers to interview questions, though. An interview Question and Answer discussion can be very helpful to both these individuals.  It is simply a way to go back over the building blocks of a topic.  Many times a simple review like this will help “jog” your memory, and all those previously-memorized facts will come flooding back to you.  It is not a way to re-learn a topic, but a way to remind yourself of what you already know. A Question and Answer discussion can also be a way to go over old topics in a more interesting manner.  Especially if you have been working in the industry, or taking lots of classes on the topic, everything you read can sound like a repeat of what you already know.  Going over a topic in a new format can make the material seem fresh and interesting.  And an interested mind will be more engaged and remember more in the end. Interview Questions and Answers are Harmful A common argument against a Question and Answer discussion is that it will give someone a “cheat sheet.” A new guy with relatively little experience can read the interview questions and answers, and then memorize them. When an interviewer asks him the same questions, he will repeat the answers and get the job. Honestly, is he good hire because he memorized the interview questions? Wouldn’t it be better for the interviewer to hire someone with actual experience?  The answer is not as easy as it seems – there are many different factors to be considered. If the interviewer is asking fundamentals-related questions only, he gets the answers he wants to hear, and then hires this first candidate – there is a good chance that he is hiring based on personality rather than experience.  If the interviewer is smart he will ask deeper questions, have more than one person on the interview team, and interview a variety of candidates.  If one interviewee happens to memorize some answers, it usually doesn’t mean he will automatically get the job at the expense of more qualified candidates. Another argument against interview Question and Answers is that it will give candidates a false sense of confidence, and that they will appear more qualified than they are. Well, if that is true, it will not last after the first interview when the candidate is asked difficult questions and he cannot find the answers in the list of interview Questions and Answers.  Besides, confidence is one of the best things to walk into an interview with! In today’s competitive job market, there are often hundreds of candidates applying for the same position.  With so many applicants to choose from, interviewers must make decisions about who to call back and who to hire based on their gut feeling.  One drawback to reading an interview Question and Answer article is that you might sound very boring in your interview – saying the same thing as every single candidate, and parroting answers that sound like someone else wrote them for you – because they did.  However, it is definitely better to go to an interview prepared, just make sure that you give a lot of thought to your answers to make them sound like your own voice.  Remember that you will be hired based on your skills as well as your personality, so don’t think that having all the right answers will make get you hired.  A good interviewee will be prepared, confident, and know how to stand out. My Opinion A list of interview Questions and Answers is really helpful as a refresher or for beginners. To really ace an interview, one needs to have real-world, hands-on experience with SQL Server as well. Interview questions just serve as a starter or easy read for experienced professionals. When I have to learn new technology, I often search online for interview questions and get an idea about the breadth and depth of the technology. Next Action I am going to write about interview Questions and Answers for next 30 days. I have previously written a series of interview questions and answers; now I have re-written them keeping the latest version of SQL Server and current industry progress in mind. If you have faced interesting interview questions or situations, please write to me and I will publish them as a guest post. If you want me to add few more details, leave a comment and I will make sure that I do my best to accommodate. Tomorrow we will start the interview Questions and Answers series, with a few interesting stories, best practices and guest posts. We will have a prize give-away and other awards when the series ends. List of all the Interview Questions and Answers Series blogs Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, PostADay, SQL, SQL Authority, SQL Interview Questions and Answers, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology

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  • Developer Training – Employee Morals and Ethics – Part 2

    - by pinaldave
    Developer Training - Importance and Significance - Part 1 Developer Training – Employee Morals and Ethics – Part 2 Developer Training – Difficult Questions and Alternative Perspective - Part 3 Developer Training – Various Options for Developer Training – Part 4 Developer Training – A Conclusive Summary- Part 5 If you have been reading this series of posts about Developer Training, you can probably determine where my mind lies in the matter – firmly “pro.”  There are many reasons to think that training is an excellent idea for the company.  In the end, it may seem like the company gets all the benefits and the employee has just wasted a few hours in a dark, stuffy room.  However, don’t let yourself be fooled, this is not the case! Training, Company and YOU! Do not forget, that as an employee, you are your company’s best asset.  Training is meant to benefit the company, of course, but in the end, YOU, the employee, is the one who walks away with a lot of useful knowledge in your head.  This post will discuss what to do with that knowledge, how to acquire it, and who should pay for it. Eternal Question – Who Pays for Training? When the subject of training comes up, money is often the sticky issue.  Some companies will argue that because the employee is the one who benefits the most, he or she should pay for it.  Of course, whenever money is discuss, emotions tend to follow along, and being told you have to pay money for mandatory training often results in very unhappy employees – the opposite result of what the training was supposed to accomplish.  Therefore, many companies will pay for the training.  However, if your company is reluctant to pay for necessary training, or is hesitant to pay for a specific course that is extremely expensive, there is always the art of compromise.  The employee and the company can split the cost of the training – after all, both the company and the employee will be benefiting. [Click on following image to answer important question] Click to Enlarge  This kind of “hybrid” pay scheme can be split any way that is mutually beneficial.  There is the obvious 50/50 split, but for extremely expensive classes or conferences, this still might be prohibitively expensive for the employee.  If you are facing this situation, here are some example solutions you could suggest to your employer:  travel reimbursement, paid leave, payment for only the tuition.  There are even more complex solutions – the company could pay back the employee after the training and project has been completed. Training is not Vacation Once the classes have been settled on, and the question of payment has been answered, it is time to attend your class or travel to your conference!  The first rule is one that your mothers probably instilled in you as well – have a good attitude.  While you might be looking forward to your time off work, going to an interesting class, hopefully with some friends and coworkers, but do not mistake this time as a vacation.  It can be tempting to only have fun, but don’t forget to learn as well.  I call this “attending sincerely.”  Pay attention, have an open mind and good attitude, and don’t forget to take notes!  You might be surprised how many people will want to see what you learned when you go back. Report Back the Learning When you get back to work, those notes will come in handy.  Your supervisor and coworkers might want you to give a short presentation about what you learned.  Attending these classes can make you almost a celebrity.  Don’t be too nervous about these presentations, and don’t feel like they are meant to be a test of your dedication.  Many people will be genuinely curious – and maybe a little jealous that you go to go learn something new.  Be generous with your notes and be willing to pass your learning on to others through mini-training sessions of your own. [Click on following image to answer important question] Click to Enlarge Practice New Learning On top of helping to train others, don’t forget to put your new knowledge to use!  Your notes will come in handy for this, and you can even include your plans for the future in your presentation when you return.  This is a good way to demonstrate to your bosses that the money they paid (hopefully they paid!) is going to be put to good use. Feedback to Manager When you return, be sure to set aside a few minutes to talk about your training with your manager.  Be perfectly honest – your manager wants to know the good and the bad.  If you had a truly miserable time, do not lie and say it was the best experience – you and others may be forced to attend the same training over and over again!  Of course, you do not want to sound like a complainer, so make sure that your summary includes the good news as well.  Your manager may be able to help you understand more of what they wanted you to learn, too. Win-Win Situation In the end, remember that training is supposed to be a benefit to the employer as well as the employee.  Make sure that you share your information and that you give feedback about how you felt the sessions went as well as how you think this training can be implemented at the company immediately. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: Developer Training, PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology

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  • SQLAuthority News – Meeting SQL Friends – SQLPASS 2011 Event Log

    - by pinaldave
    One of the biggest reason I go to SQLPASS is that my friends are going there too. There are so many friends with whom I often talk on Facebook and Twitter but I rarely get time to meet them as well talk with them. One thing I am usually sure that many fo them will be for sure attend SQLPASS. This is one event which every SQL Server Enthusiast should attend. Just like everybody I had pleasant time to meet many of my SQL friends. There were so many friends that I met and I did not click photo. There were so many friends who clicked photo in their camera and I do not have them. Here are 1% of the photos which I have. If you are not in the photo, it does not mean I have less respect to our friendship. Please post link to our photo together :) I was very fortunate that I was able to snap a quick photograph with Pinal Dave with Dr. David DeWitt. I stood outside of the hall waiting for Dr. to show up and when he was heading down from convention center I requested him if I can have one photo for my memory lane and very politely he agreed to have one. It indeed made my day! Pinal Dave with Dr. David DeWitt Every single time I met Steve, I make sure I have one photo for my memory. Steve is so kind every single time. If you know SQL and do not know Steve Jones, you do not know SQL (IMHO). Following is the photograph with Michael McLean. More details about this photo in future blog post! Pinal Dave, Michael McLean, and Rick Morelan Arnie always shares his wisdom with me. I still remember when I very first time visited USA, I was standing alone in corner and Arnie walked to me and introduced to every single person he know. Talking to Arnie is always pleasure and inspiring. Arnie Rowland and Pinal Dave I am now published author and have written two books so far. I am fortunate to have Rick Morelan as Co-author of both of my books. He is great guy and very easy to become friends with. I am very much impressed by him and his kindness during book co-authoring. Here is very first of our photograph together at SQLPASS. Rick Morelan and Pinal Dave Diego Nogare and I have been talking for long time on twitter and on various social media channels. I finally got chance to meet my friend from Brazil. It was excellent experience to meet a friend whom one wants to meet for long time and had never got chance earlier. Buck Woody – who does not know Buck. He is funny, kind and most important friends of every one. Buck is so kind that he does not hesitate to approach people even though he is famous and most known in community. Every time I meet him I learn something. He is always smiling and approachable. Pinal Dave and Buck Woddy Rushabh Mehta is current SQL PASS president and personal friend. He has always smiling face and tremendous love for SQL community. I often wonder where he gets all the time for all the time and efforts he puts in for community. I never miss a chance to meet and greet him. Even though he is renowned SQL Guru and extremely busy person – every single time I meet him he always asks me – “How is Nupur and Shaivi?” He even remembers my wife and daughters name. I am touched. Rushabh Mehta and Pinal Dave Nigel Sammy has extremely well sense of humor and passion from community. We have excellent synergy while we are together. The attached photo is taken while I was talking to him on Seattle Shoreline about SQL. Pinal Dave and Nigel Sammy Rick Morelan wanted my this trip to be memorable. I am vegetarian and I told him that I do not like Seafood. Well, to prove the point, he took me to fantastic Seafood restaurant in Seattle and treated me with mouth watering vegetarian dishes. I think when I go to Seattle next time, I am going to make him to take me again to the same place. Rick, Rushabh, Pinal and Paras Well, this is a short summary of few of the friends I met at Seattle. What is the life without friends, eh? Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, PostADay, SQL, SQL Authority, SQL PASS, SQL Query, SQL Server, SQL Tips and Tricks, SQLAuthority Author Visit, SQLAuthority News, T SQL, Technology

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  • SQL SERVER – List of Article on Expressor Data Integration Platform

    - by pinaldave
    The ability to transform data into meaningful and actionable information is the most important information in current business world. In this fast growing and changing business needs effective data integration is single most important thing in making proper decision making. I have been following expressor software since November 2010, when I met expressor team in Seattle. Here are my posts on their innovative data integration platform and expressor Studio, a free desktop ETL tool: 4 Tips for ETL Software IDE Developers Introduction to Adaptive ETL Tool – How adaptive is your ETL? Sharing your ETL Resources Across Applications with Ease expressor Studio Includes Powerful Scripting Capabilities expressor 3.2 Release Review 5 Tips for Improving Your Data with expressor Studio As I had mentioned in some of my blog posts on them, I encourage you to download and test-drive their Studio product – it’s free. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: PostADay, SQL, SQL Authority, SQL Documentation, SQL Download, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology Tagged: SSIS

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  • SQLAuthority News – Community Tech Days – A SQL Legends in Ahmedabad – December 11, 2010

    - by pinaldave
    Ahmedabad is going to be fortunate city again on December 11. We are going to have SQL Server Legends present at the prestigious event of Community Tech Days in Ahmedabad. The venue details are as following: H K Hall, H K College Campus, Near Handloom House, Opp. Natraj Cinema, Ashram Road, Ahmedabad – 380009 Click here to Registration for the event. Agenda of the event is as following. 10:15am – 10:30am     Welcome – Pinal Dave 10:30am – 11:15am     SQL Tips and Tricks for .NET Developers by Jacob Sebastian 11:15am – 11:30am     Tea Break 11:30am – 12:15pm     Best Database Practice for SharePoint Server by Pinal Dave 12:15pm – 01:00pm     Self Service Business Intelligence by Rushabh Mehta 01:00pm – 02:00pm     Lunch 02:00pm – 02:45pm     Managing your future, Managing your time by Vinod Kumar 02:45pm – 03:30pm     Windows Azure News and Introducing Storage Services by Mahesh Devjibhai Dhola 03:30pm – 03:45pm     Tea Break 03:45pm – 04:30pm     Improve Silverlight application with Threads and MEF by Prabhjot Singh Bakshi 04:30pm – 04:45pm     Thank you – Mahesh Devjibhai Dhola Ahmedabad considers itself extremely fortunate when there are SQL Legends presenting on various subjects in front of community. Here is brief introduction about them in my own words. (Their names are in order of the agenda). 1) Jacob Sebastian (SQL Server MVP) – This person needs no introduction. Every developer and programmer in Ahmedabad and India knows him. He is the one man who is founder of various community-related ideas like SQL Challenges, SQL Quiz and BeyondRelational. He works with me on all the community-related activities; we are extremely good friends. 2) Rushabh Mehta (SQL Server MVP) – If you use SQL Server – you know this man. He is the President of SQL Server of Professional Association (PASS) and one of the leading Business Intelligence (BI) Experts renowned in the world. He has blessed Ahmedabad once before and now doing once again this year. 3) Vinod Kumar (Microsoft Evangelist – SQL Server & BI) – Ahmedabad remembers him very well. During his last visit to Ahmedabad, a fight had almost broke outside the hall amidst the rush to listen him. There were more people standing and listening to him than those who were seated. This is one man Ahmedabad will never forget. 4) and Myself. I will not rate myself in the league of abovementioned experts, but I must say that I am fortunate to have friends like those above. We also have two strong .NET presenters – Mahesh and Prabhjot. During this event, there will be plenty of giveaways, lots of fun, demos and pure technical talk, specifically no marketing and promotion – just pure technical talk. The most interesting part is that all the SQL Legends – Jacob, Rushabh and Vinod are for sure presenting on SQL Server but with a twist. Jacob – He is going to talk about .NET and SQL – Optimization Techniques Rushabh – He is going to talk about SQL and BI – Self Service BI Vinod – He is going to talk about professional development of developers – Managing Time Pinal – Best Practices for SharePoint Database Administrators – SharePoint DBA – I have presented this session earlier. I promise this event is going to be one of the best events held ever. You can read about the earlier event over here. ?Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: About Me, MVP, Pinal Dave, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, SQLAuthority News, T SQL, Technology

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  • SQLAuthority News – Virtual Launch Event for Office 2010 – Contest – Win MS Office License

    - by pinaldave
    Office products are integral products of any PC. I accept that without Office Suites, I can not survive or make enough leaving. I am blogger and use word to create my blogs. I am SQL Server Trainer  and I use PowerPoint as my presentation tool. I am SQL Server consultant and I use Excel to keep my work log. I can not see my life with Office Tools. Just like any other Microsoft Product there is strong community following Office Tools. Please count me in. The same community is hosting a Virtual Launch Event for Office 2010 on May 25 and 26th. The webcasts is FREE to attend and people can take part either online or by going to the nearest available center. The sessions will be delivered by MVPs. To register please visit: http://www.meraoffice.com. In June, limited cities will be hosting Community Launch Events for Office 2010. At the launch events, attendees will get to see Office 2010 in action and learn how to do their work better with Office 2010.  The details are available on http://office.merawindows.com. To support one of the largest community, I am announcing one contents. It is very easy to take part in the contest. You just have to answer one very simple question. Contest: Choose best option: With which Microsoft Office Product Powerpivot is associated? Options: 1) PowerPoint 2) Excel 3) Word Hint: http://search.sqlauthority.com Rules: Winner will be awarded 1 Office 2007 Home and Student. This will be freely upgradeable to Office 2010 once it releases in June. The winners will be sent emails and they will redeem their awards via microsoftstore.co.in The prizes can only be shipped to India and Indian residents are eligible. Winner will be selected by selected community leaders and MVPs at their sole discretion. Winner will be informed by email about the award. Most creative and informative comment will win the contest. Please spread the words about this contest. SQLAuthority.com will also send SQL Server book to the person who generates the most traffic to this blog post using Twitter, Facebook and other social media. This competition is also open to Indian residents only. I will measure the traffic using my wordpress.com stats plugin. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, SQLAuthority News, T SQL, Technology Tagged: Office

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  • SQL SERVER – Data Pages in Buffer Pool – Data Stored in Memory Cache

    - by pinaldave
    This will drop all the clean buffers so we will be able to start again from there. Now, run the following script and check the execution plan of the query. Have you ever wondered what types of data are there in your cache? During SQL Server Trainings, I am usually asked if there is any way one can know how much data in a table is stored in the memory cache? The more detailed question I usually get is if there are multiple indexes on table (and used in a query), were the data of the single table stored multiple times in the memory cache or only for a single time? Here is a query you can run to figure out what kind of data is stored in the cache. USE AdventureWorks GO SELECT COUNT(*) AS cached_pages_count, name AS BaseTableName, IndexName, IndexTypeDesc FROM sys.dm_os_buffer_descriptors AS bd INNER JOIN ( SELECT s_obj.name, s_obj.index_id, s_obj.allocation_unit_id, s_obj.OBJECT_ID, i.name IndexName, i.type_desc IndexTypeDesc FROM ( SELECT OBJECT_NAME(OBJECT_ID) AS name, index_id ,allocation_unit_id, OBJECT_ID FROM sys.allocation_units AS au INNER JOIN sys.partitions AS p ON au.container_id = p.hobt_id AND (au.type = 1 OR au.type = 3) UNION ALL SELECT OBJECT_NAME(OBJECT_ID) AS name, index_id, allocation_unit_id, OBJECT_ID FROM sys.allocation_units AS au INNER JOIN sys.partitions AS p ON au.container_id = p.partition_id AND au.type = 2 ) AS s_obj LEFT JOIN sys.indexes i ON i.index_id = s_obj.index_id AND i.OBJECT_ID = s_obj.OBJECT_ID ) AS obj ON bd.allocation_unit_id = obj.allocation_unit_id WHERE database_id = DB_ID() GROUP BY name, index_id, IndexName, IndexTypeDesc ORDER BY cached_pages_count DESC; GO Now let us run the query above and observe the output of the same. We can see in the above query that there are four columns. Cached_Pages_Count lists the pages cached in the memory. BaseTableName lists the original base table from which data pages are cached. IndexName lists the name of the index from which pages are cached. IndexTypeDesc lists the type of index. Now, let us do one more experience here. Please note that you should not run this test on a production server as it can extremely reduce the performance of the database. DBCC DROPCLEANBUFFERS This will drop all the clean buffers and we will be able to start again from there. Now run following script and check the execution plan for the same. USE AdventureWorks GO SELECT UnitPrice, ModifiedDate FROM Sales.SalesOrderDetail WHERE SalesOrderDetailID BETWEEN 1 AND 100 GO The execution plans contain the usage of two different indexes. Now, let us run the script that checks the pages cached in SQL Server. It will give us the following output. It is clear from the Resultset that when more than one index is used, datapages related to both or all of the indexes are stored in Memory Cache separately. Let me know what you think of this article. I had a great pleasure while writing this article because I was able to write on this subject, which I like the most. In the next article, we will exactly see what data are cached and those that are not cached, using a few undocumented commands. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: DMV, Pinal Dave, SQL, SQL Authority, SQL Optimization, SQL Query, SQL Scripts, SQL Server, SQL Tips and Tricks, T SQL, Technology Tagged: SQL DMV

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  • SQLAuthority News – Book Review – Beginning T-SQL 2008 by Kathi Kellenberger

    - by pinaldave
    Beginning T-SQL 2008 by Kathi Kellenberger Amazon Link Detail Review: Beginning T-SQL 2008 is one of the best books on the market if you are just beginning to work with Microsoft SQL, or have a little bit of experience and need to learn more quickly. Each chapter of the book introduces a new subject, and builds upon topics covered in previous chapters.  The author of the book, Kathi Kellenberger understands that you need to form a solid foundation of knowledge before moving on to new topics, and sets up each subject nicely.  Because the chapters move in an orderly progression, you continue to use skills you learned earlier. One of the best features of Beginning T-SQL 2008 is that each chapter has multiple examples and exercises.  Many books introduce a topic and then never go back to it.  This book gives enough examples that you will be familiar with the subject when you come across it in real life.  The exercises at the end of the chapter mean that you will be using the skills you learned – and there is no better way to cement a subject in your brain. The book also includes discussions of the common errors that programmers will come across, how to avoid them, and how to fix them if they happen.  Ms. Kellenberger understands that not only do mistakes happen, but they are bound to happen if you aren’t trained properly.  Mistakes are part of the learning process! The book begins by discussions relational theory, so that programmers will understand the way T-SQL works from the ground up.  It also walks readers through writing accurate queries, combining set-based and procedural processing, embedding logic in stored functions, and so much more. Overall, the main goal of Beginning T-SQL 2008 is to introduce novices to SQL programming, and quickly familiarize them with the basics of running the program.  The book is written with the idea that readers will not know any of the technical terms or vocabulary.  However, if you are a little more familiar with SQL and looking to become better, you will still find this book very helpful. Ratting: 4.5+ Stars Summary: I must recommend Beginning T-SQL 2008 highly enough.  If you are going to buy any beginners guide to Transect-SQL, this is the one you should spend your money on.  You can save yourself a lot of time and effort later by using this very affordable manual to learn the basics, which will allow you to become an expert much faster. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, SQLAuthority Book Review, SQLAuthority News, T SQL, Technology

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  • SQLAuthority News – The Best Quotes of “Who Wrote This?” Contest

    - by pinaldave
    I am a frequent reader of Brent Ozar PLF, it is one of my favorite blogs. A recent post announced a “Who Wrote This?” contest to see if readers could tell their three contributors apart based on some writing samples. Here are my favorite lines from the sample paragraphs, from each of the three “mystery authors.” Topic 1: Working with Bad Managers Mystery Author A – “Working with bad managers means working against my own happiness, and I’ve come to learn that there’s no changing bad managers.” I love this line because, as anyone who has had a bad manager knows, often a lot of self-doubt rises up. We all have to remember that sometimes the problem is out of our control. Mystery Author B – “Mentor your manager just like you would mentor a junior DBA.” Having a bad manager can be extremely depressing, and we often feel out of control. But we all need to remember that our work is a two-way street, and that sometimes we can subtly influence those above us. Mystery Author C – “The trick to working for all bad managers is to remember that they aren’t your parent. Take charge of your career.” We all also need to learn not to play the blame game. Would you rather stay in a place where you are unhappy, or would you rather take charge of your life? I hope most people would pick the latter. Topic 2: Working with Remote Teams Mystery Author A – “Like almost anything else the key is to make sure that everyone on the team has an understanding of how and when communication will occur.” Communication is so important. I cannot over emphasize how much. And this one line captures how I feel and even communicates the idea clearly! Mystery Author B – “The key to remote team success is verifiable trust: feeling confident that invisible team members are doing the right amount of the right thing at the right time.” I think this line not only captures the key aspects of remote work – verifiable work and trust – but there were so many lines that followed that I loved and could not fit here. The whole paragraph is a list for successful remote work. Everyone could benefit from reading it. Mystery Author C – “What seems clear, precise, and specific in one time zone comes across as vague, soupy, and just plain weird in another.” You know what? I just love this description. The author is right – sometimes vague e-mails really do seem soupy and weird! Topic 3: Working with Your Nemesis Mystery Author A – “Every job is temporary, but your reputation stays with you.” Everyone needs to remember this. The workplace is meant to be a professional arena, and many people have the opinion that work is temporary and disposable. No one wants to work with co-worker like that. Mystery Author B – “Unhealthy conflict is going to lead to leaving three week old tuna fish sandwiches in someone’s desk drawer.” Sometimes humor really is the best policy! Mystery Author C – “Oh no, it’s that guy.” This might seem like a weird phrase to choose as my favorite from an entire paragraph. But the whole piece was written in the form of a story of co-workers getting drunk and plotting against a nemesis. It was too funny to overlook, but too long to post here. A must read! Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, SQLAuthority News, T SQL, Technology

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  • SQL SERVER – A Picture is Worth a Thousand Words – A Collection of Inspiring and Funny Posts by Vinod Kumar

    - by pinaldave
    One of the most popular quotes is: A picture is worth a thousand words. Working on this concept I started a series over my blog called the “Picture Post”. Rather than rambling over tons of material over text, we are trying to give you a capsule mode of the blog in a quick glance. Some of the picture posts already available over my blog are: Correlation of Ego and Work: Ego and Pride most of the times become a hindrance when we work inside a team. Take this cue, the first ever Picture post was published. Simple and easy to understand concept. Would want to say, Ego is the biggest enemy to humans. Read Original Post. Success (Perception Vs Reality): Personally, have always thought success is not something the talented achieve with the opportunity presented to them, but success is developed using the opportunity in hand now. In this fast paced world where success is pre-defined and convoluted by metrics it is hard to understand how complex it can sometimes be. So I took a stab at this concept in a simple way. Read Original Post. Doing Vs Saying: As Einstein would describe, Insanity is doing the same thing over and over again and expecting different results. Given the amount of information we get, it is difficult to keep track, learn and implement the same. If you were ever reminded of your college days, there will always be 5-6 people doing different things and we naturally try to emulate what they are doing. This could be from competitive exams GMAT, GRE, CAT, Higher-Ed, B-School hunting etc. Rather than saying you are going to do, it is best to do and then say!!! Read Original Picture Post. Your View Vs Management View: Being in the corporate world can be really demanding and we keep asking this question – “Why me?” when the performance appraisal process ends. In this post I just want to ask you one frank opinion – “Are you really self-critical in your assessments?”. If that is the case there shouldn’t be any heartburns or surprises. If you had just one thing to take back, well forget what others are getting but invest time in making yourself better because that is going to take you longer and further in your career. Read Picture Post. Blogging lifecycle for majority: I am happy and fortunate to be in this blog post because this picture post surely doesn’t apply to SQLAuthority where consistency and persistence have been the hallmark of the blog. For the majority others, who have a tendency to start a blog, get into slumber for a while and write saying they want to get back to blogging, the picture post was specifically done for them. Paradox of being someone else: It is always a dream that we want to become somebody and in this process of doing so, we become nobody. In this constant tussle of lost identity we forget to enjoy the moment that is in front of us. I just depicted this using a simple analogy of our constant struggle to get to the other side, just to realize we missed the wonderful moments. Grass is not greener on the other side, but grass is greener where we water the surface. Read Picture Post. And on the lighter side… Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: About Me, PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology

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  • SQLAuthority News – 18 Seconds of Fame – My PASS Experience

    - by pinaldave
    Happy Holidays to All of YOU! Life is full of little and happy surprises. I think Christmas and Santa are based on it. I just received very interesting email earlier today, I had no idea about it. Earlier this year, I had visited Seattle to attend SQLPASS – read the complete summary over here: SQLAuthority News – SQLPASS Nov 8-11, 2010-Seattle – An Alternative Look at Experience. While I was walking down, someone has stopped me and asked if they can talk to me for 15 seconds, I said yes and they had shot quick movie with mobile. The conversation was very quick and I had forgotten about it. Today I received email from one of the blog reader about it being on YouTube. Honestly, I did not know if this was ever going to be on YouTube. I am surprised and thrilled. Watch my 18 seconds fame movie. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: About Me, Pinal Dave, SQL, SQL Authority, SQL Optimization, SQL Performance, SQL Query, SQL Server, SQL Tips and Tricks, SQLAuthority Author Visit, T SQL, Technology

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  • SQLAuthority News – Fast Track Data Warehouse 3.0 Reference Guide

    - by pinaldave
    http://msdn.microsoft.com/en-us/library/gg605238.aspx I am very excited that Fast Track Data Warehouse 3.0 reference guide has been announced. As a consultant I have always enjoyed working with Fast Track Data Warehouse project as it truly expresses the potential of the SQL Server Engine. Here is few details of the enhancement of the Fast Track Data Warehouse 3.0 reference architecture. The SQL Server Fast Track Data Warehouse initiative provides a basic methodology and concrete examples for the deployment of balanced hardware and database configuration for a data warehousing workload. Balance is measured across the key components of a SQL Server installation; storage, server, application settings, and configuration settings for each component are evaluated. Description Note FTDW 3.0 Architecture Basic component architecture for FT 3.0 based systems. New Memory Guidelines Minimum and maximum tested memory configurations by server socket count. Additional Startup Options Notes for T-834 and setting for Lock Pages in Memory. Storage Configuration RAID1+0 now standard (RAID1 was used in FT 2.0). Evaluating Fragmentation Query provided for evaluating logical fragmentation. Loading Data Additional options for CI table loads. MCR Additional detail and explanation of FTDW MCR Rating. Read white paper on fast track data warehousing. Reference: Pinal Dave (http://blog.SQLAuthority.com)   Filed under: Business Intelligence, Data Warehousing, PostADay, SQL, SQL Authority, SQL Documentation, SQL Download, SQL Query, SQL Server, SQL Tips and Tricks, SQL White Papers, SQLAuthority News, T SQL, Technology

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  • SQLAuthority Book Review – Professional SQL Server 2008 Internals and Troubleshooting

    - by pinaldave
    Professional SQL Server 2008 Internals and Troubleshooting by Christian Bolton, Justin Langford, Brent Ozar, James Rowland-Jones, Steven Wort Link to Amazon (Worldwide) Link to Flipkart (India) Brief Review: Having a book on internal and associating that with real life is “almost” an impossible task. The reason for using the word “almost” is because this book has accomplished this [...]

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  • SQLAuthority News – 2 New Books – FREE Books and Book Signing at #SQLPASS 2012

    - by pinaldave
    As an author the most interesting task is to participate in Book Signing Events. If you are at SQLPASS – we are going to have a lot of book signing events. Here is the good news! MY NEW BOOKS ARE OUT! SQL 2012 Functions Limited Edition Click to Expand This book is a very special edition book. Our current plans is to run this book for the limited edition. You can avail this book from Amazon and it will soon come to India. Join following book signing events where you will get this book for free. Wednesday, November 7, 2012 7pm-8pm - Embarcadero Booth Book Signing (FREE BOOK) Thursday, November 8, 2012 12pm-1pm - Embarcadero Booth Book Signing (FREE BOOK) SQL Queries 2012 Joes 2 Pros Volume1 Click to Expand This is my first book this year which will be available in bookstores. Last Year I published 3 books and this year this is my first book. This book is available on Amazon over here and it will come to India very soon. Join following book signing events where you will get this book for free. Wednesday, November 7, 2012 12pm-1pm – Book Signing at Exhibit Hall Joes Pros booth#117 (FREE BOOK) If you are attending SQLPASS you may get this book’s Autographed Special Edition for FREE if you attend following book signing events. Rest all the time – I will be at Exhibition Hall Joes 2 Pros Booth #117. Stop by for the goodies! Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: Joes 2 Pros, PostADay, SQL, SQL Authority, SQL PASS, SQL Query, SQL Server, SQL Tips and Tricks, SQLAuthority Book Review, SQLAuthority News, SQLServer, T SQL, Technology

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  • SQL SERVER – Auto Recovery File Settings in SSMS – SQL in Sixty Seconds #034 – Video

    - by pinaldave
    Every developer once in a while facing an unfortunate situation where they have not yet saved the work and their SQL Server Management Studio crashes. Well, you can minimize the loss by optimizing auto recovery settings. In this video we can see how to set the auto recovery settings. Go to SSMS >> Tools >> Options >> Environment >> AutoRecover There are two different settings: 1) Save AutoRecover Information Every Minutes This option will save the SQL Query file at certain interval. Set this option to minimum value possible to avoid loss. If you have set this value to 5, in the worst possible case, you can loose last 5 minutes of the work. 2) Keep AutoRecover Information for Days This option will preserve the AutoRecovery information for specified days. Though, I suggest in case of accident open SQL Server Management Studio right away and recover your file. Do not procrastinate this important task for future dates. Related Tips in SQL in Sixty Seconds: Manage Help Settings – CTRL + ALT + F1 SSMS 2012 Reset Keyboard Shortcuts to Default A Cool Trick – Restoring the Default SQL Server Management Studio – SSMS Color Coding SQL Server Management Studio Status Bar – SQL in Sixty Seconds #023 – Video Clear Drop Down List of Recent Connection From SQL Server Management Studio SELECT TOP Shortcut in SQL Server Management Studio (SSMS) What would you like to see in the next SQL in Sixty Seconds video? Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: Database, Pinal Dave, PostADay, SQL, SQL Authority, SQL in Sixty Seconds, SQL Query, SQL Scripts, SQL Server, SQL Server Management Studio, SQL Tips and Tricks, T SQL, Technology, Video Tagged: Excel

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  • SQL SERVER – Concurrency Basics – Guest Post by Vinod Kumar

    - by pinaldave
    This guest post is by Vinod Kumar. Vinod Kumar has worked with SQL Server extensively since joining the industry over a decade ago. Working on various versions from SQL Server 7.0, Oracle 7.3 and other database technologies – he now works with the Microsoft Technology Center (MTC) as a Technology Architect. Let us read the blog post in Vinod’s own voice. Learning is always fun when it comes to SQL Server and learning the basics again can be more fun. I did write about Transaction Logs and recovery over my blogs and the concept of simplifying the basics is a challenge. In the real world we always see checks and queues for a process – say railway reservation, banks, customer supports etc there is a process of line and queue to facilitate everyone. Shorter the queue higher is the efficiency of system (a.k.a higher is the concurrency). Every database does implement this using checks like locking, blocking mechanisms and they implement the standards in a way to facilitate higher concurrency. In this post, let us talk about the topic of Concurrency and what are the various aspects that one needs to know about concurrency inside SQL Server. Let us learn the concepts as one-liners: Concurrency can be defined as the ability of multiple processes to access or change shared data at the same time. The greater the number of concurrent user processes that can be active without interfering with each other, the greater the concurrency of the database system. Concurrency is reduced when a process that is changing data prevents other processes from reading that data or when a process that is reading data prevents other processes from changing that data. Concurrency is also affected when multiple processes are attempting to change the same data simultaneously. Two approaches to managing concurrent data access: Optimistic Concurrency Model Pessimistic Concurrency Model Concurrency Models Pessimistic Concurrency Default behavior: acquire locks to block access to data that another process is using. Assumes that enough data modification operations are in the system that any given read operation is likely affected by a data modification made by another user (assumes conflicts will occur). Avoids conflicts by acquiring a lock on data being read so no other processes can modify that data. Also acquires locks on data being modified so no other processes can access the data for either reading or modifying. Readers block writer, writers block readers and writers. Optimistic Concurrency Assumes that there are sufficiently few conflicting data modification operations in the system that any single transaction is unlikely to modify data that another transaction is modifying. Default behavior of optimistic concurrency is to use row versioning to allow data readers to see the state of the data before the modification occurs. Older versions of the data are saved so a process reading data can see the data as it was when the process started reading and not affected by any changes being made to that data. Processes modifying the data is unaffected by processes reading the data because the reader is accessing a saved version of the data rows. Readers do not block writers and writers do not block readers, but, writers can and will block writers. Transaction Processing A transaction is the basic unit of work in SQL Server. Transaction consists of SQL commands that read and update the database but the update is not considered final until a COMMIT command is issued (at least for an explicit transaction: marked with a BEGIN TRAN and the end is marked by a COMMIT TRAN or ROLLBACK TRAN). Transactions must exhibit all the ACID properties of a transaction. ACID Properties Transaction processing must guarantee the consistency and recoverability of SQL Server databases. Ensures all transactions are performed as a single unit of work regardless of hardware or system failure. A – Atomicity C – Consistency I – Isolation D- Durability Atomicity: Each transaction is treated as all or nothing – it either commits or aborts. Consistency: ensures that a transaction won’t allow the system to arrive at an incorrect logical state – the data must always be logically correct.  Consistency is honored even in the event of a system failure. Isolation: separates concurrent transactions from the updates of other incomplete transactions. SQL Server accomplishes isolation among transactions by locking data or creating row versions. Durability: After a transaction commits, the durability property ensures that the effects of the transaction persist even if a system failure occurs. If a system failure occurs while a transaction is in progress, the transaction is completely undone, leaving no partial effects on data. Transaction Dependencies In addition to supporting all four ACID properties, a transaction might exhibit few other behaviors (known as dependency problems or consistency problems). Lost Updates: Occur when two processes read the same data and both manipulate the data, changing its value and then both try to update the original data to the new value. The second process might overwrite the first update completely. Dirty Reads: Occurs when a process reads uncommitted data. If one process has changed data but not yet committed the change, another process reading the data will read it in an inconsistent state. Non-repeatable Reads: A read is non-repeatable if a process might get different values when reading the same data in two reads within the same transaction. This can happen when another process changes the data in between the reads that the first process is doing. Phantoms: Occurs when membership in a set changes. It occurs if two SELECT operations using the same predicate in the same transaction return a different number of rows. Isolation Levels SQL Server supports 5 isolation levels that control the behavior of read operations. Read Uncommitted All behaviors except for lost updates are possible. Implemented by allowing the read operations to not take any locks, and because of this, it won’t be blocked by conflicting locks acquired by other processes. The process can read data that another process has modified but not yet committed. When using the read uncommitted isolation level and scanning an entire table, SQL Server can decide to do an allocation order scan (in page-number order) instead of a logical order scan (following page pointers). If another process doing concurrent operations changes data and move rows to a new location in the table, the allocation order scan can end up reading the same row twice. Also can happen if you have read a row before it is updated and then an update moves the row to a higher page number than your scan encounters later. Performing an allocation order scan under Read Uncommitted can cause you to miss a row completely – can happen when a row on a high page number that hasn’t been read yet is updated and moved to a lower page number that has already been read. Read Committed Two varieties of read committed isolation: optimistic and pessimistic (default). Ensures that a read never reads data that another application hasn’t committed. If another transaction is updating data and has exclusive locks on data, your transaction will have to wait for the locks to be released. Your transaction must put share locks on data that are visited, which means that data might be unavailable for others to use. A share lock doesn’t prevent others from reading but prevents them from updating. Read committed (snapshot) ensures that an operation never reads uncommitted data, but not by forcing other processes to wait. SQL Server generates a version of the changed row with its previous committed values. Data being changed is still locked but other processes can see the previous versions of the data as it was before the update operation began. Repeatable Read This is a Pessimistic isolation level. Ensures that if a transaction revisits data or a query is reissued the data doesn’t change. That is, issuing the same query twice within a transaction cannot pickup any changes to data values made by another user’s transaction because no changes can be made by other transactions. However, this does allow phantom rows to appear. Preventing non-repeatable read is a desirable safeguard but cost is that all shared locks in a transaction must be held until the completion of the transaction. Snapshot Snapshot Isolation (SI) is an optimistic isolation level. Allows for processes to read older versions of committed data if the current version is locked. Difference between snapshot and read committed has to do with how old the older versions have to be. It’s possible to have two transactions executing simultaneously that give us a result that is not possible in any serial execution. Serializable This is the strongest of the pessimistic isolation level. Adds to repeatable read isolation level by ensuring that if a query is reissued rows were not added in the interim, i.e, phantoms do not appear. Preventing phantoms is another desirable safeguard, but cost of this extra safeguard is similar to that of repeatable read – all shared locks in a transaction must be held until the transaction completes. In addition serializable isolation level requires that you lock data that has been read but also data that doesn’t exist. Ex: if a SELECT returned no rows, you want it to return no. rows when the query is reissued. This is implemented in SQL Server by a special kind of lock called the key-range lock. Key-range locks require that there be an index on the column that defines the range of values. If there is no index on the column, serializable isolation requires a table lock. Gets its name from the fact that running multiple serializable transactions at the same time is equivalent of running them one at a time. Now that we understand the basics of what concurrency is, the subsequent blog posts will try to bring out the basics around locking, blocking, deadlocks because they are the fundamental blocks that make concurrency possible. Now if you are with me – let us continue learning for SQL Server Locking Basics. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: PostADay, SQL, SQL Authority, SQL Performance, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology Tagged: Concurrency

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  • SQL SERVER – 5 Tips for Improving Your Data with expressor Studio

    - by pinaldave
    It’s no secret that bad data leads to bad decisions and poor results.  However, how do you prevent dirty data from taking up residency in your data store?  Some might argue that it’s the responsibility of the person sending you the data.  While that may be true, in practice that will rarely hold up.  It doesn’t matter how many times you ask, you will get the data however they decide to provide it. So now you have bad data.  What constitutes bad data?  There are quite a few valid answers, for example: Invalid date values Inappropriate characters Wrong data Values that exceed a pre-set threshold While it is certainly possible to write your own scripts and custom SQL to identify and deal with these data anomalies, that effort often takes too long and becomes difficult to maintain.  Instead, leveraging an ETL tool like expressor Studio makes the data cleansing process much easier and faster.  Below are some tips for leveraging expressor to get your data into tip-top shape. Tip 1:     Build reusable data objects with embedded cleansing rules One of the new features in expressor Studio 3.2 is the ability to define constraints at the metadata level.  Using expressor’s concept of Semantic Types, you can define reusable data objects that have embedded logic such as constraints for dealing with dirty data.  Once defined, they can be saved as a shared atomic type and then re-applied to other data attributes in other schemas. As you can see in the figure above, I’ve defined a constraint on zip code.  I can then save the constraint rules I defined for zip code as a shared atomic type called zip_type for example.   The next time I get a different data source with a schema that also contains a zip code field, I can simply apply the shared atomic type (shown below) and the previously defined constraints will be automatically applied. Tip 2:     Unlock the power of regular expressions in Semantic Types Another powerful feature introduced in expressor Studio 3.2 is the option to use regular expressions as a constraint.   A regular expression is used to identify patterns within data.   The patterns could be something as simple as a date format or something much more complex such as a street address.  For example, I could define that a valid IP address should be made up of 4 numbers, each 0 to 255, and separated by a period.  So 192.168.23.123 might be a valid IP address whereas 888.777.0.123 would not be.   How can I account for this using regular expressions? A very simple regular expression that would look for any 4 sets of 3 digits separated by a period would be:  ^[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}$ Alternatively, the following would be the exact check for truly valid IP addresses as we had defined above:  ^(25[0-5]|2[0-4][0-9]|1[0-9]{2}|[1-9]?[0-9])\.(25[0-5]|2[0-4][0-9]|1[0-9]{2}|[1-9]?[0-9])\.(25[0-5]|2[0-4][0-9]|1[0-9]{2}|[1-9]?[0-9])\.(25[0-5]|2[0-4][0-9]|1[0-9]{2}|[1-9]?[0-9])$ .  In expressor, we would enter this regular expression as a constraint like this: Here we select the corrective action to be ‘Escalate’, meaning that the expressor Dataflow operator will decide what to do.  Some of the options include rejecting the offending record, skipping it, or aborting the dataflow. Tip 3:     Email pattern expressions that might come in handy In the example schema that I am using, there’s a field for email.  Email addresses are often entered incorrectly because people are trying to avoid spam.  While there are a lot of different ways to define what constitutes a valid email address, a quick search online yields a couple of really useful regular expressions for validating email addresses: This one is short and sweet:  \b[A-Z0-9._%+-]+@[A-Z0-9.-]+\.[A-Z]{2,4}\b (Source: http://www.regular-expressions.info/) This one is more specific about which characters are allowed:  ^([a-zA-Z0-9_\-\.]+)@((\[[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.)|(([a-zA-Z0-9\-]+\.)+))([a-zA-Z]{2,4}|[0-9]{1,3})(\]?)$ (Source: http://regexlib.com/REDetails.aspx?regexp_id=26 ) Tip 4:     Reject “dirty data” for analysis or further processing Yet another feature introduced in expressor Studio 3.2 is the ability to reject records based on constraint violations.  To capture reject records on input, simply specify Reject Record in the Error Handling setting for the Read File operator.  Then attach a Write File operator to the reject port of the Read File operator as such: Next, in the Write File operator, you can configure the expressor operator in a similar way to the Read File.  The key difference would be that the schema needs to be derived from the upstream operator as shown below: Once configured, expressor will output rejected records to the file you specified.  In addition to the rejected records, expressor also captures some diagnostic information that will be helpful towards identifying why the record was rejected.  This makes diagnosing errors much easier! Tip 5:    Use a Filter or Transform after the initial cleansing to finish the job Sometimes you may want to predicate the data cleansing on a more complex set of conditions.  For example, I may only be interested in processing data containing males over the age of 25 in certain zip codes.  Using an expressor Filter operator, you can define the conditional logic which isolates the records of importance away from the others. Alternatively, the expressor Transform operator can be used to alter the input value via a user defined algorithm or transformation.  It also supports the use of conditional logic and data can be rejected based on constraint violations. However, the best tip I can leave you with is to not constrain your solution design approach – expressor operators can be combined in many different ways to achieve the desired results.  For example, in the expressor Dataflow below, I can post-process the reject data from the Filter which did not meet my pre-defined criteria and, if successful, Funnel it back into the flow so that it gets written to the target table. I continue to be impressed that expressor offers all this functionality as part of their FREE expressor Studio desktop ETL tool, which you can download from here.  Their Studio ETL tool is absolutely free and they are very open about saying that if you want to deploy their software on a dedicated Windows Server, you need to purchase their server software, whose pricing is posted on their website. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, PostADay, SQL, SQL Authority, SQL Query, SQL Scripts, SQL Server, SQL Tips and Tricks, T SQL, Technology

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  • SQL SERVER – Index Created on View not Used Often – Observation of the View

    - by pinaldave
    I always enjoy writing about concepts on Views. Views are frequently used concepts, and so it’s not surprising that I have seen so many misconceptions about this subject. To clear such misconceptions, I have previously written the article SQL SERVER – The Limitations of the Views – Eleven and more…. I also wrote a follow up article wherein I demonstrated that without even creating index on the basic table, the query on the View will not use the View. You can read about this demonstration over here: SQL SERVER – Index Created on View not Used Often – Limitation of the View 12. I promised in that post that I would also write an article where I would demonstrate the condition where the Index will be used. I got many responses suggesting that I can do that with using NOEXPAND; I agree. I have already written about this in my original summary article. Here is a way for you to see how Index created on View can be utilized. We will do the following steps on this exercise: Create a Table Create a View Create Index On View Write SELECT with ORDER BY on View USE tempdb GO IF EXISTS (SELECT * FROM sys.views WHERE OBJECT_ID = OBJECT_ID(N'[dbo].[SampleView]')) DROP VIEW [dbo].[SampleView] GO IF EXISTS (SELECT * FROM sys.objects WHERE OBJECT_ID = OBJECT_ID(N'[dbo].[mySampleTable]') AND TYPE IN (N'U')) DROP TABLE [dbo].[mySampleTable] GO -- Create SampleTable CREATE TABLE mySampleTable (ID1 INT, ID2 INT, SomeData VARCHAR(100)) INSERT INTO mySampleTable (ID1,ID2,SomeData) SELECT TOP 100000 ROW_NUMBER() OVER (ORDER BY o1.name), ROW_NUMBER() OVER (ORDER BY o2.name), o2.name FROM sys.all_objects o1 CROSS JOIN sys.all_objects o2 GO -- Create View CREATE VIEW SampleView WITH SCHEMABINDING AS SELECT ID1,ID2,SomeData FROM dbo.mySampleTable GO -- Create Index on View CREATE UNIQUE CLUSTERED INDEX [IX_ViewSample] ON [dbo].[SampleView] ( ID2 ASC ) GO -- Select from view SELECT ID1,ID2,SomeData FROM SampleView ORDER BY ID2 GO When we check the execution plan for this , we find it clearly that the Index created on the View is utilized. ORDER BY clause uses the Index created on the View. I hope this makes the puzzle simpler on how the Index is used on the View. Again, I strongly recommend reading my earlier series about the limitations of the Views found here: SQL SERVER – The Limitations of the Views – Eleven and more…. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: Pinal Dave, SQL, SQL Authority, SQL Optimization, SQL Performance, SQL Query, SQL Scripts, SQL Server, SQL Tips and Tricks, SQL View, T SQL, Technology

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  • SQLAuthority News – Windows Efficiency Tricks and Tips – Personal Technology Tip

    - by pinaldave
    This is the second post in my series about my favorite Technology Tips, and I wanted to focus on my favorite Microsoft product.  Choosing just one topic to cover was too hard, though.  There are so many interesting things I have to share that I am forced to turn this second installment into a five-part post.  My five favorite Windows tips and tricks. 1) You can open multiple applications using the task bar. With the new Windows 7 taskbar, you can start navigating with just one click.  For example, you can launch Word by clicking on the icon on your taskbar, and if you are using multiple different programs at the same time, you can simply click on the icon to return to Word.  However, what if you need to open another Word document, or begin a new one?  Clicking on the Word icon is just going to bring you back to your original program.  Just click on the Word icon again while holding down the shift key, and you’ll open up a new document. 2) Navigate the screen with the touch of a button – and not your mouse button. Yes, we live in a pampered age.  We have access to amazing technology, and it just gets better every year.  But have you ever found yourself wishing that right when you were in the middle of something, you didn’t have to interrupt your work flow be reaching for your mouse to navigate through the screen?  Yes, we have all been guilty of this pampered wish.  But Windows has delivered!  Now you can move your application window using your arrow keys. Lock the window to the left, right hand screen: Win+left Arrow and Win+right Arrow Maximize & minimize: Win+up arrow and Win+down arrow Minimize all items on screen: Win+M Return to your original folder, or browse through all open windows: Alt+up arrow, Alt+Left Arrow, or Alt+right arrow Close down or reopen all windows: win+home 3) Are you one of the few people who still uses Command Prompt? You know who you are, and you aren’t ashamed to still use this option that so many people have forgotten about it.  You can easily access it by holding down the shift key while RIGHT clicking on any folder. 4) Quickly select multiple files without using your mouse. We all know how to select multiple files or folders by Ctrl-clicking or Shift-clicking multiple items.  But all of us have tried this, and then accidentally released Ctrl, only to lose all our precious work.  Now there is a way to select only the files you want through a check box system.  First, go to Windows Explorer, click Organize, and then “Folder and Search Options.”  Go to the View tab, and under advanced settings, you can find a box that says “Use check boxes to select items.”  Once this has been selected, you will be able to hover your mouse over any file and a check box will appear.  This makes selecting multiple, random files quick and easy. 5) Make more out of remote access. If you work anywhere in the tech field, you are probably the go-to for computer help with friends and family, and you know the usefulness of remote access (ok, some of us use this extensively at work, as well, but we all have friends and family who rely on our skills!).  Often it is necessary to restart a computer, which is impossible in remote access as the computer will not show the shutdown menu.  To force the computer to do your wishes, we return to Command Prompt.  Open Command Prompt and type “shutdown /s” for shutdown, or “shutdown /r” for restart. I hope you will find above five tricks which I use in my daily use very important. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, SQLAuthority News, T SQL, Technology Tagged: Personal Technology

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  • SQL SERVER – PAGELATCH_DT, PAGELATCH_EX, PAGELATCH_KP, PAGELATCH_SH, PAGELATCH_UP – Wait Type – Day 12 of 28

    - by pinaldave
    This is another common wait type. However, I still frequently see people getting confused with PAGEIOLATCH_X and PAGELATCH_X wait types. Actually, there is a big difference between the two. PAGEIOLATCH is related to IO issues, while PAGELATCH is not related to IO issues but is oftentimes linked to a buffer issue. Before we delve deeper in this interesting topic, first let us understand what Latch is. Latches are internal SQL Server locks which can be described as very lightweight and short-term synchronization objects. Latches are not primarily to protect pages being read from disk into memory. It’s a synchronization object for any in-memory access to any portion of a log or data file.[Updated based on comment of Paul Randal] The difference between locks and latches is that locks seal all the involved resources throughout the duration of the transactions (and other processes will have no access to the object), whereas latches locks the resources during the time when the data is changed. This way, a latch is able to maintain the integrity of the data between storage engine and data cache. A latch is a short-living lock that is put on resources on buffer cache and in the physical disk when data is moved in either directions. As soon as the data is moved, the latch is released. Now, let us understand the wait stat type  related to latches. From Book On-Line: PAGELATCH_DT Occurs when a task is waiting on a latch for a buffer that is not in an I/O request. The latch request is in Destroy mode. PAGELATCH_EX Occurs when a task is waiting on a latch for a buffer that is not in an I/O request. The latch request is in Exclusive mode. PAGELATCH_KP Occurs when a task is waiting on a latch for a buffer that is not in an I/O request. The latch request is in Keep mode. PAGELATCH_SH Occurs when a task is waiting on a latch for a buffer that is not in an I/O request. The latch request is in Shared mode. PAGELATCH_UP Occurs when a task is waiting on a latch for a buffer that is not in an I/O request. The latch request is in Update mode. PAGELATCH_X Explanation: When there is a contention of access of the in-memory pages, this wait type shows up. It is quite possible that some of the pages in the memory are of very high demand. For the SQL Server to access them and put a latch on the pages, it will have to wait. This wait type is usually created at the same time. Additionally, it is commonly visible when the TempDB has higher contention as well. If there are indexes that are heavily used, contention can be created as well, leading to this wait type. Reducing PAGELATCH_X wait: The following counters are useful to understand the status of the PAGELATCH: Average Latch Wait Time (ms): The wait time for latch requests that have to wait. Latch Waits/sec: This is the number of latch requests that could not be granted immediately. Total Latch Wait Time (ms): This is the total latch wait time for latch requests in the last second. If there is TempDB contention, I suggest that you read the blog post of Robert Davis right away. He has written an excellent blog post regarding how to find out TempDB contention. The same blog post explains the terms in the allocation of GAM, SGAM and PFS. If there was a TempDB contention, Paul Randal explains the optimal settings for the TempDB in his misconceptions series. Trace Flag 1118 can be useful but use it very carefully. I totally understand that this blog post is not as clear as my other blog posts. I suggest if this wait stats is on one of your higher wait type. Do leave a comment or send me an email and I will get back to you with my solution for your situation. May the looking at all other wait stats and types together become effective as this wait type can help suggest proper bottleneck in your system. Read all the post in the Wait Types and Queue series. Note: The information presented here is from my experience and there is no way that I claim it to be accurate. I suggest reading Book OnLine for further clarification. All the discussions of Wait Stats in this blog are generic and vary from system to system. It is recommended that you test this on a development server before implementing it to a production server. Reference: Pinal Dave (http://blog.SQLAuthority.com)   Filed under: Pinal Dave, PostADay, SQL, SQL Authority, SQL Query, SQL Scripts, SQL Server, SQL Tips and Tricks, SQL Wait Stats, SQL Wait Types, T SQL, Technology

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