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• SQLAuthority News – Stay Connected and Social Media

  - by pinaldave

  I think I have finally gotten back my faith in social media. If you are following my blog I am sure you are aware of my views on social media – SQLAuthority News – Social Media Confusion – Twitter, FaceBook, LinkedIn and Me. I was not happy about how social media was evolving. Whenever I go to Twitter, LinkedIn or Facebook, I noticed the same updates everywhere. I just thought I was wasting my time doing the same thing everywhere. I strongly believe that there is no dictator on internet. Nobody has authority over others, everybody can express their ideas as long as it is not violating others privacy and it is not morally wrong. I have decided that instead of trying to improve the world, I should change myself and adjust my needs. Here are few things I have done to relieve my social media confusion. Twitter I un-followed people who were taking up my time with too many updates. I un-followed people who hardly updated at all. I did not follow anybody else’s list, as I have no control over who other people follow. I follow not only serious SQL people but some fun stuff as well. I removed all my friends who were on Facebook and repeating the same updates on Twitter. I engage with them on Facebook. I followed people who are very conversational on Twitter. I let anybody follow me. I update all my blog posts through at least five tweets online. I decided to re-tweet at least five of my favorite tweets of the day, this way I force myself to remain active in the community. Follow me on Twitter! LinkedIn I updated my career and professional info on LinkedIn. I keep my LinkedIn profile updated with my latest jobs and career news. I let anybody connect with me on LinkedIn. I specify my email address in my profile, keeping it easy for those who want to add me. I read all the profile related updates of my connections – it is very valuable to know who is where and what changes are happening. I do not add my personal tweets or comments in LinkedIn profile. I just keep it professional. Link with me at LinkedIn Facebook I use Facebook only for personal friends. I visit all of my friends at regular intervals and make sure that they are really my friends. I often remove my friends from my Twitter list who are sending duplicate updates. I upload my family photos as well as family updates on Facebook, making sure that only my approved friends are able to read my updates. I keep my Facebook very personal and I often chat with my friends on Facebook chat. I am no longer confused about social media and I think I am using it appropriately. As I said, one cannot decide for others how to use social media, you can only decide for yourself. I have finally found my peace with social media. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: About Me, Pinal Dave, PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology

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• Big Data – How to become a Data Scientist and Learn Data Science? – Day 19 of 21

  - by Pinal Dave

  In yesterday’s blog post we learned the importance of the analytics in Big Data Story. In this article we will understand how to become a Data Scientist for Big Data Story. Data Scientist is a new buzz word, everyone seems to be wanting to become Data Scientist. Let us go over a few key topics related to Data Scientist in this blog post. First of all we will understand what is a Data Scientist. In the new world of Big Data, I see pretty much everyone wants to become Data Scientist and there are lots of people I have already met who claims that they are Data Scientist. When I ask what is their role, I have got a wide variety of answers. What is Data Scientist? Data scientists are the experts who understand various aspects of the business and know how to strategies data to achieve the business goals. They should have a solid foundation of various data algorithms, modeling and statistics methodology. What do Data Scientists do? Data scientists understand the data very well. They just go beyond the regular data algorithms and builds interesting trends from available data. They innovate and resurrect the entire new meaning from the existing data. They are artists in disguise of computer analyst. They look at the data traditionally as well as explore various new ways to look at the data. Data Scientists do not wait to build their solutions from existing data. They think creatively, they think before the data has entered into the system. Data Scientists are visionary experts who understands the business needs and plan ahead of the time, this tremendously help to build solutions at rapid speed. Besides being data expert, the major quality of Data Scientists is “curiosity”. They always wonder about what more they can get from their existing data and how to get maximum out of future incoming data. Data Scientists do wonders with the data, which goes beyond the job descriptions of Data Analysist or Business Analysist. Skills Required for Data Scientists Here are few of the skills a Data Scientist must have. Expert level skills with statistical tools like SAS, Excel, R etc. Understanding Mathematical Models Hands-on with Visualization Tools like Tableau, PowerPivots, D3. j’s etc. Analytical skills to understand business needs Communication skills On the technology front any Data Scientists should know underlying technologies like (Hadoop, Cloudera) as well as their entire ecosystem (programming language, analysis and visualization tools etc.) . Remember that for becoming a successful Data Scientist one require have par excellent skills, just having a degree in a relevant education field will not suffice. Final Note Data Scientists is indeed very exciting job profile. As per research there are not enough Data Scientists in the world to handle the current data explosion. In near future Data is going to expand exponentially, and the need of the Data Scientists will increase along with it. It is indeed the job one should focus if you like data and science of statistics. Courtesy: emc Tomorrow In tomorrow’s blog post we will discuss about various Big Data Learning resources. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: Big Data, PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, T SQL

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• Big Data – Operational Databases Supporting Big Data – Columnar, Graph and Spatial Database – Day 14 of 21

  - by Pinal Dave

  In yesterday’s blog post we learned the importance of the Key-Value Pair Databases and Document Databases in the Big Data Story. In this article we will understand the role of Columnar, Graph and Spatial Database supporting Big Data Story. Now we will see a few of the examples of the operational databases. Relational Databases (The day before yesterday’s post) NoSQL Databases (The day before yesterday’s post) Key-Value Pair Databases (Yesterday’s post) Document Databases (Yesterday’s post) Columnar Databases (Tomorrow’s post) Graph Databases (Today’s post) Spatial Databases (Today’s post) Columnar Databases  Relational Database is a row store database or a row oriented database. Columnar databases are column oriented or column store databases. As we discussed earlier in Big Data we have different kinds of data and we need to store different kinds of data in the database. When we have columnar database it is very easy to do so as we can just add a new column to the columnar database. HBase is one of the most popular columnar databases. It uses Hadoop file system and MapReduce for its core data storage. However, remember this is not a good solution for every application. This is particularly good for the database where there is high volume incremental data is gathered and processed. Graph Databases For a highly interconnected data it is suitable to use Graph Database. This database has node relationship structure. Nodes and relationships contain a Key Value Pair where data is stored. The major advantage of this database is that it supports faster navigation among various relationships. For example, Facebook uses a graph database to list and demonstrate various relationships between users. Neo4J is one of the most popular open source graph database. One of the major dis-advantage of the Graph Database is that it is not possible to self-reference (self joins in the RDBMS terms) and there might be real world scenarios where this might be required and graph database does not support it. Spatial Databases  We all use Foursquare, Google+ as well Facebook Check-ins for location aware check-ins. All the location aware applications figure out the position of the phone with the help of Global Positioning System (GPS). Think about it, so many different users at different location in the world and checking-in all together. Additionally, the applications now feature reach and users are demanding more and more information from them, for example like movies, coffee shop or places see. They are all running with the help of Spatial Databases. Spatial data are standardize by the Open Geospatial Consortium known as OGC. Spatial data helps answering many interesting questions like “Distance between two locations, area of interesting places etc.” When we think of it, it is very clear that handing spatial data and returning meaningful result is one big task when there are millions of users moving dynamically from one place to another place & requesting various spatial information. PostGIS/OpenGIS suite is very popular spatial database. It runs as a layer implementation on the RDBMS PostgreSQL. This makes it totally unique as it offers best from both the worlds. Courtesy: mushroom network Tomorrow In tomorrow’s blog post we will discuss about very important components of the Big Data Ecosystem – Hive. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: Big Data, PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, T SQL

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• SQL SERVER – Renaming Index – Index Naming Conventions

  - by pinaldave

  If you are regular reader of this blog, you must be aware of that there are two kinds of blog posts 1) I share what I learn recently 2) I share what I learn and request your participation. Today’s blog post is where I need your opinion to make this blog post a good reference for future. Background Story Recently I came across system where users have changed the name of the few of the table to match their new standard naming convention. The name of the table should be self explanatory and they should have explain their purpose without either opening it or reading documentations. Well, not every time this is possible but again this should be the goal of any database modeler. Well, I no way encourage the name of the tables to be too long like ‘ContainsDetailsofNewInvoices’. May be the name of the table should be ‘Invoices’ and table should contain a column with New/Processed bit filed to indicate if the invoice is processed or not (if necessary). Coming back to original story, the database had several tables of which the name were changed. Story Continues… To continue the story let me take simple example. There was a table with the name  ’ReceivedInvoices’, it was changed to new name as ‘TblInvoices’. As per their new naming standard they had to prefix every talbe with the words ‘Tbl’ and prefix every view with the letters ‘Vw’. Personally I do not see any need of the prefix but again, that issue is not here to discuss.  Now after changing the name of the table they faced very interesting situation. They had few indexes on the table which had name of the table. Let us take an example. Old Name of Table: ReceivedInvoice Old Name of Index: Index_ReceivedInvoice1 Here is the new names New Name of Table: TblInvoices New Name of Index: ??? Well, their dilemma was what should be the new naming convention of the Indexes. Here is a quick proposal of the Index naming convention. Do let me know your opinion. If Index is Primary Clustered Index: PK_TableName If Index is  Non-clustered Index: IX_TableName_ColumnName1_ColumnName2… If Index is Unique Non-clustered Index: UX_TableName_ColumnName1_ColumnName2… If Index is Columnstore Non-clustered Index: CL_TableName Here ColumnName is the column on which index is created. As there can be only one Primary Key Index and Columnstore Index per table, they do not require ColumnName in the name of the index. The purpose of this new naming convention is to increase readability. When any user come across this index, without opening their properties or definition, user can will know the details of the index. T-SQL script to Rename Indexes Here is quick T-SQL script to rename Indexes EXEC sp_rename N'SchemaName.TableName.IndexName', N'New_IndexName', N'INDEX'; GO Your Contribute Please Well, the organization has already defined above four guidelines, personally I follow very similar guidelines too. I have seen many variations like adding prefixes CL for Clustered Index and NCL for Non-clustered Index. I have often seen many not using UX prefix for Unique Index but rather use generic IX prefix only. Now do you think if they have missed anything in the coding standard. Is NCI and CI prefixed required to additionally describe the index names. I have once received suggestion to even add fill factor in the index name – which I do not recommend at all. What do you think should be ideal name of the index, so it explains all the most important properties? Additionally, you are welcome to vote if you believe changing the name of index is just waste of time and energy.  Note: The purpose of the blog post is to encourage all to participate with their ideas. I will write follow up blog posts in future compiling all the suggestions. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: PostADay, SQL, SQL Authority, SQL Index, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology

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• SQL SERVER – Asynchronous Update and Timestamp – Check if Row Values are Changed Since Last Retrieve

  - by pinaldave

  Here is the question received just this morning. “Pinal, Our application is much different than other application you might have come across. In simple words, I would like to call it Asynchronous Updated Application. We need your quick opinion about one of the situation which we are facing. From business side: We have bidding system (similar to eBay but not exactly) and where multiple parties bid on one item, during the last few minutes of bidding many parties try to bid at the same time with the same price. When they hit submit, we would like to check if the original data which they retrieved is changed or not. If the original data which they have retrieved is the same, we will accept their new proposed price. If original data are changed, they will have to resubmit the data with new price. From technical side: We have a row which we retrieve in our application. Multiple users are retrieving the same row. Some of the users will update the value of the row and submit. However, only the very first user should be allowed to update the row and remaining all the users will have to re-fetch the row and updated it once again. We do not want to lock any record as that will create other problems. Do you have any solution for this kind of situation?” Fantastic Question. I believe there is good chance that we can use timestamp datatype in this kind of application. Before we continue let us see following simple example. USE tempdb GO CREATE TABLE SampleTable (ID INT, Col1 VARCHAR(100), TimeStampCol TIMESTAMP) GO INSERT INTO SampleTable (ID, Col1) VALUES (1, 'FirstVal') GO SELECT ID, Col1, TimeStampCol FROM SampleTable st GO UPDATE SampleTable SET Col1 = 'NextValue' GO SELECT ID, Col1, TimeStampCol FROM SampleTable st GO DROP TABLE SampleTable GO Now let us see the resultset. Here is the simple explanation of the scenario. We created a table with simple column with TIMESTAMP datatype. When we inserted a very first value the timestamp was generated. When we updated any value in that row, the timestamp was updated with the new value. Every single time when we update any value in the row, it will generate new timestamp value. Now let us apply this in an original question’s scenario. In that case multiple users are retrieving the same row. Everybody will have the same now same TimeStamp with them. Before any user update any value they should once again retrieve the timestamp from the table and compare with the timestamp they have with them. If both of the timestamp have the same value – the original row has not been updated and we can safely update the row with the new value. After initial update, now the row will contain a new timestamp. Any subsequent update to the same row should also go to the same process of checking the value of the timestamp they have in their memory. In this case, the timestamp from memory will be different from the timestamp in the row. This indicates that row in the table has changed and new updates should not be allowed. I believe timestamp can be very very useful in this kind of scenario. Is there any better alternative? Please leave a comment with the suggestion and I will post on the blog with due credit. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology

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• SQLAuthority News – Speaking at Southeast Asia SharePoint Conference 2013 – Singapore

  - by pinaldave

  Two years ago I spoke at Southeast Asia SharePoint Conference 2011, Singapore and I had a fantastic time to present to the Singapore audience. The session was very well received and lots of interest was generated. The event is back again this year and with much bigger scale. I will be presenting on SQL Server and Sharepoint subject at the conference. Session Details: Title: Performance in 60 Seconds – Database Tricks Every SharePoint Developer & Admin MUST Know Abstract: SharePoint Developers and System Administrators often come across situations where they face a slow server response, even though their hardware specifications are above  par. This session is for all the SharePoint Developers who want their server to perform at blazing fast speed but want to invest very little time to make it happen. We will go over various database tricks which require absolutely no time to master and require practically no SQL coding at all. After attending this session, Developers will only need 60 seconds to improve performance of their database server in their SharePoint implementation. Date and Time: January 18, 20013 - 3:15 PM-4:15 PM Location: Max Atria is located at Singapore Expo, 1 Expo Drive, Singapore Tel 65 6403 2160 This session will cover lots of interesting tips and tricks about SQL Server and SharePoint co-exists together. I promise that every attendee will walk out with a trick which they can walk out of session and directly apply to their production server to improve its performance. The event is going to be again fantastic event – if you are in Singapore – you must not miss this event. If you are planning vacation – this is the right time to take days off and travel to Singapore for vacation. The event features over 30 sessions to choose from, focus on three areas of business gain: Exploring Information, Improving Productivity and Making it Work. This event has an excellent line up of international speakers (speakers traveling from the USA, Australia, New Zealand, Sri Lanka and India). Register early to reserve a spot at your choice of more than 30 classes taught by Microsoft Certified Masters, MVPs, and other top SharePoint experts! Here I have attempted to answer a few of the questions which every SharePoint professional half: Which sessions suit my skill level? Click here. What sessions are right for me? Click here. Which sessions are of my interests? Click here. Which sessions are on when? Click here. If you register by next Friday, 14, December – you can save $126 on the regular price of the conference. Prizes, Giveaways and … I love conference goodies – I collect them as a souvenir . This event is known for its generous prizes. The first 100 people to register on the day will get a SPECIAL gift at the event. Additionally there are exhibitor booth give away too. Here is the page listing all the prizes and giveaways. Do leave a comment or send me email if you are going to the event, we can sit together and have a coffee. 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 – Solution – User Not Able to See Any User Created Object in Tables – Security and Permissions Issue

  - by pinaldave

  There is an old quote “A Picture is Worth a Thousand Words”. I believe this quote immensely. Quite often I get phone calls that something is not working if I can help. My reaction is in most of the cases, I need to know more, send me exact error or a screenshot. Until and unless I see the error or reproduce the scenario myself I prefer not to comment. Yesterday I got a similar phone call from an old friend, where he was not sure what is going on. Here is what he said. “When I try to connect to SQL Server, it lets me connect just fine as well let me open and explore the database. I noticed that I do not see any user created instances but when my colleague attempts to connect to the server, he is able to explore the database as well see all the user created tables and other objects. Can you help me fix it? “ My immediate reaction was he was facing security and permission issue. However, to make the same recommendation I suggested that he send me a screenshot of his own SSMS and his friend’s SSMS. After carefully looking at both the screenshots, I was very confident about the issue and we were able to resolve the issue. Let us reproduce the same scenario and many there is some learning for us. Issue: User not able to see user created objects First let us see the image of my friend’s SSMS screen. (Recreated on my machine) Now let us see my friend’s colleague SSMS screen. (Recreated on my machine) You can see that my friend could not see the user tables but his colleague was able to do the same for sure. Now I believed it was a permissions issue. Further to this I asked him to send me another image where I can see the various permissions of the user in the database. My friends screen My friends colleagues screen This indeed proved that my friend did not have access to the AdventureWorks database and because of the same he was not able to access the database. He did have public access which means he will have similar rights as guest access. However, their SQL Server had followed my earlier advise on having limited access for guest access, which means he was not able to see any user created objects. My next question was to validate what kind of access my friend’s colleague had. He replied that the colleague is the admin of the server. I suggested that if my friend was suppose to have admin access to the database, he should request of having admin access to his colleague. My friend promptly asked for the same to his colleague and on following screen he added him as an admin. You can do the same using following T-SQL script as well. USE [AdventureWorks2012] GO ALTER ROLE [db_owner] ADD MEMBER [testguest] GO Once my friend was admin he was able to access all the user objects just like he was expecting. Please note, this complete exercise was done on a development server. One should not play around with security on live or production server. Security is such an issue, which should be left with only senior administrator of the server. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: PostADay, SQL, SQL Authority, SQL Query, SQL Security, SQL Server, SQL Tips and Tricks, T SQL, Technology

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• SQL SERVER – Configuring Interactive Cleansing Suggestion Min Score for Suggestions in Data Quality Services (DQS) – Sensitivity of Suggestion

  - by pinaldave

  Earlier I talked about what kind of questions, I do not like when I get asked. Today we will go over the question which I like when I get asked the same. One of the reader practices various steps in my earlier blog post Step by Step Guide to Beginning Data Quality Services in SQL Server 2012 – Introduction to DQS. While reading the blog post he noticed that Data Quality Services is not providing very helpful suggestions. He wrote an email to me about it. Let us go over his email. “Pinal, I noticed in one of your images that DQS is not providing very helpful suggestions. First of all DQS should be able to make intelligent guesses and make the necessary correction by itself. If it cannot do the same, in that case, it should give us intelligent suggestions but in the image included here, I see the suggestions are not there as well. Why is it so? Would you please tell me how to increase the numbers of suggestion? I do understand this may not be preferable solution in many case but all the business cases go on it depends. There are cases when the high sensitivity required and there are cases when higher sensitivities are not required. I would like to seek your help here. –Sriram MD” This is indeed a great question. I see that Sriram understands that every system is different and every application has a different need. I will not have to tell him this most important concept. The question is about how to change the sensitivity of suggestions for correction in DQS. Well, this option is available under the configuration tab in the DQS client. Once you click on Configuration you will see the following screen. Click the Tab of General Settings. You will see the section of Interactive Cleansing. Under this second there is the first option of “Min score for suggestions”. As this is set to 0.7 every suggestion which matches 0.7 probabilities or higher probability are displayed under the suggestion tab. You can see in the following image that there is no suggestion as the min score for suggestions is set to 0.7 and there is no record which qualifies to that much confidence. Now let us change the value of Min Score for suggestion to 0.5. The lower value increased the confidence of DQS to give further suggestion to values which are over 0.5. However, in our case the suggestions which it provides are also accurate. This may not be true for your sample. Every sample is different so you should manually review it before approving them. I guess, this is a simple blog post to demonstrate how to change the confidence value for the suggestions which Data Quality Services provides. Use this feature with care and always tune it according to your datasets and record diversity. Reference: Pinal Dave (http://blog.SQLAuthority.com)       Filed under: PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology Tagged: Data Quality Services, DQS

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• SQLAuthority News – Advantages of Distance Learning

  - by Pinal Dave

  Distance education is extremely popular – almost overnight, it seems.  Almost everyone has taken an online course, or knows someone who has, or is considering joining an online school.  There are many advantages and disadvantages to attending an online school – but the same can be said of attending a physical school!  Let’s take a look at the top reasons to use distance education. 1) Flexibility.  Physical universities are usually willing to make some concessions to student – like night classes, study hours, and online networks.  However, nothing is going to beat the flexibility of distance education.  You can attend classes and take notes anytime, anywhere, wearing anything you’d like! 2) Affordability.  We don’t need to get into hard numbers to understand how an expensive university can be.  Students are taking on more and more debt just to get an education.  Many of these fees pay for room, board, and facilities.   Distance education cuts out all these costs, and makes attending school much more affordable for the average student. 3) Try before you buy.  Did you know that the average college student changes his or her major 10 times before they graduate?  You can imagine that this kind of indecision plays a huge part in WHEN you graduate – not being able to make up your mind can cost you big bucks if you have to stay in school for extra years!  Distance education allows you to take different classes from a wide range of disciplines.  Do you want to study forensic science or English literature?  Now you don’t have to pay for classes you can’t afford just to find out. 4) Pace yourself.  Some students struggle in a traditional classroom setting – classes can be taught too fast, too slow, or there are too many distractions.  Distance education allows mature students to set the pace themselves.  They can rewatch lectures they didn’t catch the first time, or go through classes quickly if they are already familiar with the material – cutting out the chance of burning out or getting bored. 5) Lifelong learning.  Maybe you already have a degree, but would like to learn more about your field, or a related field, or maybe even about something completely unrelated – just because you are curious!  Distance education allows you to learn whatever you want ,whenever you want (and yes, wearing anything you’d like!). 6) Attend whatever college you want.  Because of the popularity of distance education, physical campuses are getting in on the game by offering online courses – often just uploaded versions of classes already taught at their campus.  Ever wanted to attend Harvard, but knew you couldn’t get in?  Take a class online!  Of course, you probably should not attempt to lie and say you have a Harvard degree, but Ivy League colleges are prestigious because they are the best in their field – take advantage of the best by taking an online course! I am a big believer in continuing education, whether it is online courses, returning to school, or even take informal classes online.  Distance education can be a great way to accomplish these goals and become a lifelong learner. My friends at provides training through virtual classrooms for students who want to avoid travelling. Distance learning course allows IT aspirants to connect with trainers using the internet.  I encourage everyone to check it out! Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, SQL Training, T SQL, Technology

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• Big Data – Interacting with Hadoop – What is Sqoop? – What is Zookeeper? – Day 17 of 21

  - by Pinal Dave

  In yesterday’s blog post we learned the importance of the Pig and Pig Latin in Big Data Story. In this article we will understand what is Sqoop and Zookeeper in Big Data Story. There are two most important components one should learn when learning about interacting with Hadoop – Sqoop and Zookper. What is Sqoop? Most of the business stores their data in RDBMS as well as other data warehouse solutions. They need a way to move data to the Hadoop system to do various processing and return it back to RDBMS from Hadoop system. The data movement can happen in real time or at various intervals in bulk. We need a tool which can help us move this data from SQL to Hadoop and from Hadoop to SQL. Sqoop (SQL to Hadoop) is such a tool which extract data from non-Hadoop data sources and transform them into the format which Hadoop can use it and later it loads them into HDFS. Essentially it is ETL tool where it Extracts, Transform and Load from SQL to Hadoop. The best part is that it also does extract data from Hadoop and loads them to Non-SQL (or RDBMS) data stores. Essentially, Sqoop is a command line tool which does SQL to Hadoop and Hadoop to SQL. It is a command line interpreter. It creates MapReduce job behinds the scene to import data from an external database to HDFS. It is very effective and easy to learn tool for nonprogrammers. What is Zookeeper? ZooKeeper is a centralized service for maintaining configuration information, naming, providing distributed synchronization, and providing group services. In other words Zookeeper is a replicated synchronization service with eventual consistency. In simpler words – in Hadoop cluster there are many different nodes and one node is master. Let us assume that master node fails due to any reason. In this case, the role of the master node has to be transferred to a different node. The main role of the master node is managing the writers as that task requires persistence in order of writing. In this kind of scenario Zookeeper will assign new master node and make sure that Hadoop cluster performs without any glitch. Zookeeper is the Hadoop’s method of coordinating all the elements of these distributed systems. Here are few of the tasks which Zookeepr is responsible for. Zookeeper manages the entire workflow of starting and stopping various nodes in the Hadoop’s cluster. In Hadoop cluster when any processes need certain configuration to complete the task. Zookeeper makes sure that certain node gets necessary configuration consistently. In case of the master node fails, Zookeepr can assign new master node and make sure cluster works as expected. There many other tasks Zookeeper performance when it is about Hadoop cluster and communication. Basically without the help of Zookeeper it is not possible to design any new fault tolerant distributed application. Tomorrow In tomorrow’s blog post we will discuss about very important components of the Big Data Ecosystem – Big Data Analytics. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: Big Data, PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, T SQL

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• SQL Authority News – Secret Tool Box of Successful Bloggers: 52 Tips to Build a High Traffic Top Ranking Blog

  - by Pinal Dave

  When I started this blog, it was meant as a bookmark for myself for helpful tips and tricks.  Gradually, it grew into a blog that others were reading and commenting on.  While SQL and databases are my first love and the reason I started this blog, the side effect was that I discovered I loved writing.  I discovered a secret goal I didn’t even know I wanted – I wanted to become an author.  For a long time, writing this blog satisfied that urge.  Gradually, though, I wanted to see my name in print. 12th Book Over the past few years I have authored and co-authored a number of books – they are all based on my knowledge of SQL Server, and were meant to spread my years of experience into the world, to share what I have learned with my community.  I currently have elevan of these “manuals” available for sale.  As exciting as it was to see my name in print, I still felt that there was more I could do as an author. That is when I realized that I am more than just a SQL expert.  I have been writing this blog now for more than 10 years, and it grew from a personal bookmark to a thriving website with over 2 million views per month.  I thought to myself “I could write a book about how to create a successful blog!”  And that is exactly what I did.  I am extremely excited to share with all of you my new book – “Secret Toolbox of Successful Bloggers.” A Labor of Love This project has been a labor of love for me.  It started out as a series for this blog – I would post one article a week until I felt the topic had been covered.  I found that as I wrote, new topics kept popping up in my mind, and eventually this small blog series grew into a full book.  The blog series was large enough to last a whole year, so I definitely thought that it could be a full book.  Ideas on how to become a successful blogger were so frequent that, I will admit, I feel like there is so much I left out of this book.  I had a lot more to say than I originally thought! I am so excited to be sharing this book with all of you.  I am so passionate about this topic, and I feel like there are so many people who can benefit from this book.  I know that when I started this blog, I did not know what I was doing, and I would have loved a “helping hand” to tell what to do and what not to do.  If this book can act that way to any of my readers, I feel it is a success. Rules of Thumb If you are interested in the topic of becoming a blogger, as you read this book, keep in mind that it is suggestions only.  Blogging is so new to the world that while there are “rules of thumb” about what to do and what not to do, a map of steps (“first, do x, then do y”) is not going to work for every single blogger.  This book is meant to encourage new bloggers to put their content out there in the world, to be brave and create a community like the one I have here at SQL Authority.  I have gained so much from this community, I wanted to give something back, and this book is just one small part. I hope that everyone who reads this books finds at least one helpful tip, and that everyone can experience the joy of blogging.  That is the whole reason I wrote this book, and what I hope everyone takes away from it. Where Can You Get It? You can get the book from following URL: Kindle eBook | Print Book Reference: Pinal Dave (http://blog.SQLAuthority.com)Filed under: About Me, PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, SQLAuthority Author Visit, T SQL

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• SQL SERVER – Importance of User Without Login

  - by pinaldave

  Some questions are very open ended and it is very hard to come up with exact requirements. Here is one question I was asked in recent User Group Meeting. Question: “In recent version of SQL Server we can create user without login. What is the use of it?” Great question indeed. Let me first attempt to answer this question but after reading my answer I need your help. I want you to help him as well with adding more value to it. Answer: Let us visualize a scenario. An application has lots of different operations and many of them are very sensitive operations. The common practice was to do give application specific role which has more permissions and access level. When a regular user login (not system admin), he/she might have very restrictive permissions. The application itself had a user name and password which means applications can directly login into the database and perform the operation. Developers were well aware of the username and password as it was embedded in the application. When developer leaves the organization or when the password was changed, the part of the application had to be changed where the same username and passwords were used. Additionally, developers were able to use the same username and password and login directly to the same application. In earlier version of SQL Server there were application roles. The same is later on replaced by “User without Login”. Now let us recreate the above scenario using this new “User without Login”. In this case, User will have to login using their own credentials into SQL Server. This means that the user who is logged in will have his/her own username and password. Once the login is done in SQL Server, the user will be able to use the application. Now the database should have another User without Login which has all the necessary permissions and rights to execute various operations. Now, Application will be able to execute the script by impersonating “user without login – with more permissions”. Here there is assumed that user login does not have enough permissions and another user (without login) there are more rights. If a user knows how the application is using the database and their various operations, he can switch the context to user without login making him enable for doing further modification. Make sure to explicitly DENY view definition permission on the database. This will make things further difficult for user as he will have to know exact details to get additional permissions. If a user is System Admin all the details which I just mentioned in above three paragraphs does not apply as admin always have access to everything. Additionally, the method describes above is just one of the architecture and if someone is attempting to damage the system, they will still be able to figure out a workaround. You will have to put further auditing and policy based management to prevent such incidents and accidents. I guess this is my answer. I read it multiple times but I still feel that I am missing something. There should be more to this concept than what I have just described. I have merely described one scenario but there will be many more scenarios where this situation will be useful. Now is your turn to help – please leave a comment with the additional suggestion where exactly “User without Login” will be useful as well did I miss anything when I described above scenario. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: PostADay, SQL, SQL Authority, SQL Query, SQL Security, SQL Server, SQL Tips and Tricks, T SQL, Technology

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• SQL Authority News – Presenting at SQL Bangalore on May 3, 2014 – Performing an Effective Presentation

  - by Pinal Dave

  SQL Bangalore is a wonderful community and we always have a great response when we present on technology. It is SQL User Group and we discuss everything SQL there. This month we have SQL Server 2014 theme and we are going to have a community launch on this subject. We have the best of the best speakers presenting on SQL Server 2014 technology. Looking at the whole line of celebrity speakers, I have decided not to present on SQL Server. I will be presenting on the performance tuning subject, but with the twist of soft skills. I will be presenting on “Performing an Effective Presentation“. Trust me, you do not want to miss this presentation, I will be presenting on how to present effectively when presenting SQL Server topics. What this session will NOT have I personally believe that we all are good presenters most of the time. We can all easily call out if someone is bad presenter. There is no point talking about basics like bigger bullet points, talk loudly, talk with confidence, use better analogies etc. In simple words – this is not going to some philosophy session and boring notes. What this session will have Well, this session will tell stories of my life. It will tell how we can present about technology and SQL Server with the help of stories and personal experience. I am going to tell stories about two legends  who have inspired me. Right after that we will be doing two exercises together where we will learn quickly and effectively, how to become better speaker – instantly! There is no video recording of this session. If you want to get resources from this session, please sign up my newsletter at http://bit.ly/sqllearn Here are few of the slides from this presentation: Here is the details about the event and location Venue:Microsoft Corporation, Signature Building,Embassy Golf Links Business Park, Intermediate Ring Road, Domlur, Bangalore – 560071 The agenda is amazing – we have top line SQL Speakers. Everyone is welcome and don’t forget to get your friend along for this event. Loads to learn and tons to share !!! Keynote (20 mins) by Anupam Tiwari – Business Program Manager – GTSC Backup Enhancements with SQL Server 2014 by Amit Banerjee – PFE Microsoft Performance Enhancements with SQL Server 2014 by Sourabh Agarwal - PFE Microsoft LUNCH BREAK Performing an effective Presentation by Pinal Dave – Community Member (SQLAuthority.com) InMemory Enhancements with SQL Server 2014 by Balmukund Lakhani – Support Escalation Engg. Microsoft Some more lesser known enhancements with SQL Server 2014 by Vinod Kumar – Technical Architect Microsoft MTC Power Packed – Power BI with SQL Server by Kane Conway – Support Escalation Engg. Microsoft I am very big fan of Amit, Balmukund and Vinod – I have always watched their session and this time, I am going to once again attend their session without missing a single min. They are SQL legends, I am going to be there and learn when they are sharing their knowledge.  Reference: Pinal Dave (http://blog.sqlauthority.com)Filed under: PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, SQLAuthority Author Visit, T SQL

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• SQL Authority News – FalafelCON 2014: 2 days with the Best Developers in the World

  - by Pinal Dave

  I love presenting at various forums on various technologies. I am extremely excited that I got invited to speak at Falafel Conference 2014 in San Francisco. I will present two technology sessions on SQL Server. If you are into web development or if you just want to attend a conference with the best of the industry speakers, this may be the right conference for you. What set apart this conference from other conference is technology presented as well as speakers. Usually one has to attend very expensive and high scale event when they have to hear good speakers. At this conference, you will find quite a many industry legends are available to present on the bleeding edge technology. Here are few of the reasons why I believe you should attend this conference: Choose from four tracks covering Web, Mobile development and testing, Sitefinity, and Automated Testing, or attend sessions from all four! Learn from the best developers and testers in the business in an intimate setting. Surround yourself with your peers and the opportunity to network Learn about the latest platforms and technologies including Kendo UI, AngularJS, ASP.NET MVC, WebAPI, and more! Here are the details for the sessions which I am going to present at Falafel Conference. Secrets of SQL Server: Database Worst Practices Abstract: Chances are you have heard, or even uttered, this expression. This demo-oriented session will show many examples where database professionals were dumbfounded by their own mistakes, and could even bring back memories of your own early DBA days. The goal of this session is to expose the small details that can be dangerous to the production environment and SQL Server as a whole, as well as talk about worst practices and how to avoid them. Shedding light on some of these perils and the tricks to avoid them may even save your current job. After attending this session, Developers will only need 60 seconds to improve performance of their database server in their SharePoint implementation. We will have a quiz during the session to keep the conversation alive. Developers will walk out with scripts and knowledge that can be applied to their servers, immediately post the session. Additionally, all attendees of the session will have access to learning material presented in the session. The Unsung Hero Abstract: Slow Running Queries are the most common problem that developers face while working with SQL Server. While it is easy to blame the SQL Server for unsatisfactory performance, however the issue often persists with the way queries have been written, and how Indexes has been set up. The session will focus on the ways of identifying problems that slow down SQL Server, and Indexing tricks to fix them. Developers will walk out with scripts and knowledge that can be applied to their servers, immediately post the session. Register Now! I have learned from the Falafel Team that they are running out of tickets and soon they will close the registration.  For next 10 days the price for the registration is only USD 149. Trust me, you can’t get such a world class training and networking opportunity at such a low price. Click to Register Here! 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

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• Big Data – ClustrixDB – Extreme Scale SQL Database with Real-time Analytics, Releases Software Download – NewSQL

  - by Pinal Dave

  There are so many things to learn and there is so little time we all have. As we have little time we need to be selective to learn whatever we learn. I believe I know quite a lot of things in SQL but I still do not know what is around SQL. I have started to learn about NewSQL recently. If you wonder what is NewSQL I encourage all of you to read my blog post about NewSQL over here Big Data – Buzz Words: What is NewSQL – Day 10 of 21. NewSQL databases are quickly becoming popular – providing the scale of NoSQL with the SQL features and transactions. As a part of learning NewSQL database, I have recently started to learn about ClustrixDB. ClustrixDB has been the most mature NewSQL database used by some of the largest internet sites in the world for over 3 years, with extensive SQL support. In addition to scale, it provides fast real-time analytics by bringing massively parallel processing (MPP), available only in warehousing databases, to the transactional database. The reason I am more intrigued about learning ClustrixDB is their recent announcement on Oct 31. ClustrixDB was only available as an appliance, but now with their software release on Oct 31, everyone can use it. It is now available as forever free for up to 12 cores with community support, and there is a 45 day trial for unlimited cluster sizes. With the forever free world, I am indeed interested in ClustrixDB now. I know that few of the leading eCommerce sites in the world uses them for their transactional database. Here are few of the details I have quickly noted for ClustrixDB. ClustrixDB allows user to: Scale by simply adding nodes to the cluster with a single command Run billions of transactions a day Run fast real-time analytics Achieve high-availability with recovery from node failure Manages itself Easily migrate from MySQL as it is nearly plug-and-play compatible, use MySQL drivers, tools and replication. While I was going through the documentation I realized that ClustrixDB also has extensive support for SQL features including complex queries involving joins on a dozen or more tables, aggregates, sorts, sub-queries. It also supports stored procedures, triggers, foreign keys, partitioned and temporary tables, and fully online schema changes. It is indeed a very matured product and SQL solution. Indeed Clusterix sound very promising solution, I decided to dig a bit deeper to understand who are current customers of the Clustrix as they exist in the industry for quite a few years. Their client list is indeed very interesting and here is my quick research about them. Twoo.com – Europe’s largest social discovery (dating) site runs 4.4 Billion Transactions a day with table sizes over a Terabyte, on a 168 core cluster. EngageBDR – Top 3 in the online advertising category uses ClustrixDB to serve 6.9 billion ads a day through real-time bidding platform. Their reports went from 4 hours to 15 seconds. NoMoreRack – Top 2 fastest growing e-commerce company in US used ClustrixDB for high availability and fast growth through Amazon cloud. MakeMyTrip – India’s leading travel site runs on ClustrixDB with two clusters running as multi-master in Chennai and Bangalore. Many enterprises such as AOL, CSC, Rakuten, Symantec use ClustrixDB when their applications need scale. I must accept that I am impressed with the information I have learned so far and now is the time to do some hand’s on experience with their product. I want to learn this technology so in future when it is about NewSQL, I know what I am talking about. Read more why Clustrix explains why you ClustrixDB might be the right database for you. Download ClustrixDB with me today and install it on your machine so in future when we discuss the technical aspects of it, we all are on the same page. The software can be downloaded here. Reference : Pinal Dave (http://blog.SQLAuthority.com)Filed under: Big Data, MySQL, PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, T SQL Tagged: Clustrix

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• SQL SERVER – Unable to DELETE Project in Data Quality Projects (DQS)

  - by pinaldave

  Here is the email which made me write this blog post. When I write a blog post I write keeping in mind that if the developer is not familiar with the concept he will attempt this on the development server. If due to any reason you attempt it on any other server than your personal server, developer should make sure to have complete confidence on his own expertise and understand the risk behind it.  Well, let us read the email which I received. I have modified it a bit to remove information related to organizational and individual. “I just read your blog post on Beginning DQS. I went ahead and followed every single screenshot and it worked fine. I was able to execute the DQS project successfully. However, the same blog post got me in trouble – a serious trouble. After first successful deployment I went ahead and created a few of my own knowledge base and projects. I played around a bit and then decided to get back to real work. Now we had deployed DQS on production server only, so experiment on production server. Now, when I got back to my work, I forgot to close all the windows. My manager found the window open and have seen my test projects. He has asked me to delete my experiments immediately and have said words which I cannot write to you. Here is the problem. I am not able to delete the project which I have created earlier. I am able to open it and play with it but the delete option is disabled and grayed out (see attached image). Now I believe there is nothing wrong with this project as it was just a test project. Would you please write to my manager that it is not harmful to leave that project there as it is? It is also not using any resources. I think he will believe you.” As I said this kind of email makes me uncomfortable. I do not want someone to execute anything on production server. I often write notes and disclaimer on my post when something is dangerous to execute on production server. However, if someone is not expert with SQL Server and attempts something new on production server, I think the major issue is here with the person (admin) who gave new developer permission to production server. This has to be carefully avoided. Here was my response to the individual. “I cannot write to your manager anything as he has not asked me anything. Honestly I believe he is correct in his behavior as you should have not executed anything on the production server without prior approval and testing on the development server. Any R&D must be done on local box or development box. I suggest you request your manager to prevent access to users who does not need access. If he is a good manager, he might have already implemented by now recent event. I also see your screenshot. Here is the issue: While you were playing with project, you might have closed the project half the way, without completing it. Due to the same reason it is locked. You can open and continue from the same place where you have left the project. If you do not need the project any more. Right click on it, click on unlock the project. This will enable the DELETE option and now you can delete the project. Next time, be safe out there. It may be dangerous to have admin access to production server when not needed.“ I have yet not heard from him but I believe he will take my words positively. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology Tagged: Data Quality Services, DQS

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• SQL SERVER – Curious Case of Disappearing Rows – ON UPDATE CASCADE and ON DELETE CASCADE – T-SQL Example – Part 2 of 2

  - by pinaldave

  Yesterday I wrote a real world story of how a friend who thought they have an issue with intrusion or virus whereas the issue was really in the code. I strongly suggest you read my earlier blog post Curious Case of Disappearing Rows – ON UPDATE CASCADE and ON DELETE CASCADE – Part 1 of 2 before continuing this blog post as this is second part of the first blog post. Let me reproduce the simple scenario in T-SQL. Building Sample Data USE [TestDB] GO -- Creating Table Products CREATE TABLE [dbo].[Products]( [ProductID] [int] NOT NULL, [ProductDesc] [varchar](50) NOT NULL, CONSTRAINT [PK_Products] PRIMARY KEY CLUSTERED ( [ProductID] ASC )) ON [PRIMARY] GO -- Creating Table ProductDetails CREATE TABLE [dbo].[ProductDetails]( [ProductDetailID] [int] NOT NULL, [ProductID] [int] NOT NULL, [Total] [int] NOT NULL, CONSTRAINT [PK_ProductDetails] PRIMARY KEY CLUSTERED ( [ProductDetailID] ASC )) ON [PRIMARY] GO ALTER TABLE [dbo].[ProductDetails] WITH CHECK ADD CONSTRAINT [FK_ProductDetails_Products] FOREIGN KEY([ProductID]) REFERENCES [dbo].[Products] ([ProductID]) ON UPDATE CASCADE ON DELETE CASCADE GO -- Insert Data into Table USE TestDB GO INSERT INTO Products (ProductID, ProductDesc) SELECT 1, 'Bike' UNION ALL SELECT 2, 'Car' UNION ALL SELECT 3, 'Books' GO INSERT INTO ProductDetails ([ProductDetailID],[ProductID],[Total]) SELECT 1, 1, 200 UNION ALL SELECT 2, 1, 100 UNION ALL SELECT 3, 1, 111 UNION ALL SELECT 4, 2, 200 UNION ALL SELECT 5, 3, 100 UNION ALL SELECT 6, 3, 100 UNION ALL SELECT 7, 3, 200 GO Select Data from Tables -- Selecting Data SELECT * FROM Products SELECT * FROM ProductDetails GO Delete Data from Products Table -- Deleting Data DELETE FROM Products WHERE ProductID = 1 GO Select Data from Tables Again -- Selecting Data SELECT * FROM Products SELECT * FROM ProductDetails GO Clean up Data -- Clean up DROP TABLE ProductDetails DROP TABLE Products GO My friend was confused as there was no delete was firing over ProductsDetails Table still there was a delete happening. The reason was because there is a foreign key created between Products and ProductsDetails Table with the keywords ON DELETE CASCADE. Due to ON DELETE CASCADE whenever is specified when the data from Table A is deleted and if it is referenced in another table using foreign key it will be deleted as well. Workaround 1: Design Changes – 3 Tables Change the design to have more than two tables. Create One Product Mater Table with all the products. It should historically store all the products list in it. No products should be ever removed from it. Add another table called Current Product and it should contain only the table which should be visible in the product catalogue. Another table should be called as ProductHistory table. There should be no use of CASCADE keyword among them. Workaround 2: Design Changes - Column IsVisible You can keep the same two tables. 1) Products and 2) ProductsDetails. Add a column with BIT datatype to it and name it as a IsVisible. Now change your application code to display the catalogue based on this column. There should be no need to delete anything. Workaround 3: Bad Advices (Bad advises begins here) The reason I have said bad advices because these are going to be bad advices for sure. You should make necessary design changes and not use poor workarounds which can damage the system and database integrity further. Here are the examples 1) Do not delete the data – well, this is not a real solution but can give time to implement design changes. 2) Do not have ON CASCADE DELETE – in this case, you will have entry in productsdetails which will have no corresponding product id and later on there will be lots of confusion. 3) Duplicate Data – you can have all the data of the product table move to the product details table and repeat them at each row. Now remove CASCADE code. This will let you delete the product table rows without any issue. There are so many things wrong this suggestion, that I will not even start here. (Bad advises ends here)  Well, did I miss anything? Please help me with your suggestions. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology

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• SQL SERVER – Retrieve and Explore Database Backup without Restoring Database – Idera virtual databas

  - by pinaldave

  I recently downloaded Idera’s SQL virtual database, and tested it. There are a few things about this tool which caught my attention. My Scenario It is quite common in real life that sometimes observing or retrieving older data is necessary; however, it had changed as time passed by. The full database backup was 40 GB in size, and, to restore it on our production server, it usually takes around 16 to 22 minutes, depending on the load server that is usually present. This range in time varies from one server to another as per the configuration of the computer. Some other issues we used to have are the following: When we try to restore a large 40-GB database, we needed at least that much space on our production server. Once in a while, we even had to make changes in the restored database, and use the said changed and restored database for our purpose, making it more time-consuming. My Solution I have heard a lot about the Idera’s SQL virtual database tool.. Well, right after we started to test this tool, we found out that it really delivers what it promises. Using this software was very easy and we were able to restore our database from backup in less than 2 minutes, sparing us from the usual longer time of 16–22 minutes. The needful was finished in a total of 10 minutes. Another interesting observation is that there is no need to have an additional space for restoring the database. For complete database restoration, the single additional MB on the drive is not required anymore. We can use the database in the same way as our regular database, and there is no need for any additional configuration and setup. Let us look at the most relevant points of this product based on my initial experience: Quick restoration of the database backup No additional space required for database restoration virtual database has no physical .MDF or .LDF The database which is restored is, in fact, the backup file converted in the virtual database. DDL and DML queries can be executed against this virtually restored database. Regular backup operation can be implemented against virtual database, creating a physical .bak file that can be used for future use. There was no observed degradation in performance on the original database as well the restored virtual database. Additional T-SQL queries can be let off on the virtual database. Well, this summarizes my quick review. And, as I was saying, I am very impressed with the product and I plan to explore it more. There are many features that I have noticed in this tool, which I think can be very useful if properly understood. I had taken a few screenshots using my demo database afterwards. Let us see what other things this tool can do besides the mentioned activities. I am surprised with its performance so I want to know how exactly this feature works, specifically in the matter of why it does not create any additional files and yet, it still allows update on the virtually restored database. I guess I will have to send an e-mail to the developers of Idera and try to figure this out from them. I think this tool is very useful, and it delivers a high level of performance way more than what I expected. Soon, I will write a review for additional uses of SQL virtual database.. If you are using SQL virtual database in your production environment, I am eager to learn more about it and your experience while using it. The ‘Virtual’ Part of virtual database When I set out to test this software, I thought virtual database had something to do with Hyper-V or visualization. In fact, the virtual database is a kind of database which shows up in your SQL Server Management Studio without actually restoring or even creating it. This tool creates a database in SSMS from the backup of the same database. The backup, however, works virtually the same way as original database. Potential Usage of virtual database: As soon as I described this tool to my teammate, I think his very first reaction was, “hey, if we have this then there is no need for log shipping.” I find his comment very interesting as log shipping is something where logs are moved to another server. In fact, there are no updates on the database from log; I would rather compare it with Snapshot Replication. In fact, whatever we use, snapshot replicated database can be similarly used and configured with virtual database. I totally believe that we can use it for reporting purpose. In fact, after this database was configured, I think the uses of this tool are unlimited. I will have to spend some more time studying it and will get back to you. Click on images to see larger images. virtual database Console Harddrive Space before virtual database Setup Attach Full Backup Screen Backup on Harddrive Attach Full Backup Screen with Settings virtual database Setup – less than 60 sec virtual database Setup – Online Harddrive Space after virtual database Setup Point in Time Recovery Option – Timeline View virtual database Summary No Performance Difference between Regular DB vs Virtual DB Please note that all SQL Server MVP gets free license of this software. Reference: Pinal Dave (http://blog.SQLAuthority.com), Idera (virtual database) Filed under: Database, Pinal Dave, SQL, SQL Add-On, SQL Authority, SQL Backup and Restore, SQL Data Storage, SQL Query, SQL Server, SQL Tips and Tricks, SQL Utility, SQLAuthority News, T SQL, Technology Tagged: Idera

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• SQL SERVER – 2008 – Introduction to Snapshot Database – Restore From Snapshot

  - by pinaldave

  Snapshot database is one of the most interesting concepts that I have used at some places recently. Here is a quick definition of the subject from Book On Line: A Database Snapshot is a read-only, static view of a database (the source database). Multiple snapshots can exist on a source database and can always reside on the same server instance as the database. Each database snapshot is consistent, in terms of transactions, with the source database as of the moment of the snapshot’s creation. A snapshot persists until it is explicitly dropped by the database owner. If you do not know how Snapshot database work, here is a quick note on the subject. However, please refer to the official description on Book-on-Line for accuracy. Snapshot database is a read-only database created from an original database called the “source database”. This database operates at page level. When Snapshot database is created, it is produced on sparse files; in fact, it does not occupy any space (or occupies very little space) in the Operating System. When any data page is modified in the source database, that data page is copied to Snapshot database, making the sparse file size increases. When an unmodified data page is read in the Snapshot database, it actually reads the pages of the original database. In other words, the changes that happen in the source database are reflected in the Snapshot database. Let us see a simple example of Snapshot. In the following exercise, we will do a few operations. Please note that this script is for demo purposes only- there are a few considerations of CPU, DISK I/O and memory, which will be discussed in the future posts. Create Snapshot Delete Data from Original DB Restore Data from Snapshot First, let us create the first Snapshot database and observe the sparse file details. USE master GO -- Create Regular Database CREATE DATABASE RegularDB GO USE RegularDB GO -- Populate Regular Database with Sample Table CREATE TABLE FirstTable (ID INT, Value VARCHAR(10)) INSERT INTO FirstTable VALUES(1, 'First'); INSERT INTO FirstTable VALUES(2, 'Second'); INSERT INTO FirstTable VALUES(3, 'Third'); GO -- Create Snapshot Database CREATE DATABASE SnapshotDB ON (Name ='RegularDB', FileName='c:\SSDB.ss1') AS SNAPSHOT OF RegularDB; GO -- Select from Regular and Snapshot Database SELECT * FROM RegularDB.dbo.FirstTable; SELECT * FROM SnapshotDB.dbo.FirstTable; GO Now let us see the resultset for the same. Now let us do delete something from the Original DB and check the same details we checked before. -- Delete from Regular Database DELETE FROM RegularDB.dbo.FirstTable; GO -- Select from Regular and Snapshot Database SELECT * FROM RegularDB.dbo.FirstTable; SELECT * FROM SnapshotDB.dbo.FirstTable; GO When we check the details of sparse file created by Snapshot database, we will find some interesting details. The details of Regular DB remain the same. It clearly shows that when we delete data from Regular/Source DB, it copies the data pages to Snapshot database. This is the reason why the size of the snapshot DB is increased. Now let us take this small exercise to  the next level and restore our deleted data from Snapshot DB to Original Source DB. -- Restore Data from Snapshot Database USE master GO RESTORE DATABASE RegularDB FROM DATABASE_SNAPSHOT = 'SnapshotDB'; GO -- Select from Regular and Snapshot Database SELECT * FROM RegularDB.dbo.FirstTable; SELECT * FROM SnapshotDB.dbo.FirstTable; GO -- Clean up DROP DATABASE [SnapshotDB]; DROP DATABASE [RegularDB]; GO Now let us check the details of the select statement and we can see that we are successful able to restore the database from Snapshot Database. We can clearly see that this is a very useful feature in case you would encounter a good business that needs it. I would like to request the readers to suggest more details if they are using this feature in their business. Also, let me know if you think it can be potentially used to achieve any tasks. Complete Script of the afore- mentioned operation for easy reference is as follows: USE master GO -- Create Regular Database CREATE DATABASE RegularDB GO USE RegularDB GO -- Populate Regular Database with Sample Table CREATE TABLE FirstTable (ID INT, Value VARCHAR(10)) INSERT INTO FirstTable VALUES(1, 'First'); INSERT INTO FirstTable VALUES(2, 'Second'); INSERT INTO FirstTable VALUES(3, 'Third'); GO -- Create Snapshot Database CREATE DATABASE SnapshotDB ON (Name ='RegularDB', FileName='c:\SSDB.ss1') AS SNAPSHOT OF RegularDB; GO -- Select from Regular and Snapshot Database SELECT * FROM RegularDB.dbo.FirstTable; SELECT * FROM SnapshotDB.dbo.FirstTable; GO -- Delete from Regular Database DELETE FROM RegularDB.dbo.FirstTable; GO -- Select from Regular and Snapshot Database SELECT * FROM RegularDB.dbo.FirstTable; SELECT * FROM SnapshotDB.dbo.FirstTable; GO -- Restore Data from Snapshot Database USE master GO RESTORE DATABASE RegularDB FROM DATABASE_SNAPSHOT = 'SnapshotDB'; GO -- Select from Regular and Snapshot Database SELECT * FROM RegularDB.dbo.FirstTable; SELECT * FROM SnapshotDB.dbo.FirstTable; GO -- Clean up DROP DATABASE [SnapshotDB]; DROP DATABASE [RegularDB]; GO Reference : Pinal Dave (http://blog.SQLAuthority.com) Filed under: SQL, SQL Authority, SQL Backup and Restore, SQL Data Storage, SQL Query, SQL Server, SQL Tips and Tricks, SQLServer, T SQL, Technology

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• SQL SERVER – Beginning SQL Server: One Step at a Time – SQL Server Magazine

  - by pinaldave

  I am glad to announce that along with SQLAuthority.com, I will be blogging on the prominent site of SQL Server Magazine. My very first blog post there is already live; read here: Beginning SQL Server: One Step at a Time. My association with SQL Server Magazine has been quite long, I have written nearly 7 to 8 SQL Server articles for the print magazine and it has been a great experience. I used to stay in the United States at that time. I moved back to India for good, and during this process, I had put everything on hold for a while. Just like many things, “temporary” things become “permanent” – coming back to SQLMag was on hold for long time. Well, this New Year, things have changed – once again, I am back with my online presence at SQLMag.com. Everybody is a beginner at every task or activity at some point of his/her life: spelling words for the first time; learning how to drive for the first time, etc. No one is perfect at the start of any task, but every human is different. As time passes, we all develop our interests and begin to study our subject of interest. Most of us dream to get a job in the area of our study – however things change as time passes. I recently read somewhere online (I could not find the link again while writing this one) that all the successful people in various areas have never studied in the area in which they are successful. After going through a formal learning process of what we love, we refuse to stop learning, and we finally stop changing career and focus areas. We move, we dare and we progress. IT field is similar to our life. New IT professionals come to this field every day. There are two types of beginners – a) those who are associated with IT field but not familiar with other technologies, and b) those who are absolutely new to the IT field. Learning a new technology is always exciting and overwhelming for enthusiasts. I am working with database (in particular) for SQL Server for more than 7 years but I am still overwhelmed with so many things to learn. I continue to learn and I do not think that I should ever stop doing so. Just like everybody, I want to be in the race and get ahead in learning the technology. For the same, I am always looking for good guidance. I always try to find a good article, blog or book chapter, which can teach me what I really want to learn at this stage in my career and can be immensely helpful. Quite often, I prefer to read the material where the author does not judge me or assume my understanding. I like to read new concepts like a child, who takes his/her first steps of learning without any prior knowledge. Keeping my personal philosophy and preference in mind, I will be blogging on SQL Server Magazine site. I will be blogging on the beginners stuff. I will be blogging for them, who really want to start and make a mark in this area. I will be blogging for all those who have an extreme passion for learning. I am happy that this is a good start for this year. One of my resolutions is to help every beginner. It is totally possible that in future they all will grow and find the same article quite ‘easy‘ – well when that happens, it indicates the success of the article and material! Well, I encourage everybody to read my SQL Server Magazine blog – I will be blogging there frequently on various topics. To begin, we will be talking about performance tuning, and I assure that I will not shy away from other multiple areas. Read my SQL Server Magazine Blog: Beginning SQL Server: One Step at a Time I think the title says it all. Do leave your comments and feedback to indicate your preference of subject and interest. I am going to continue writing on subject, and the aim is of course to help grow in this field. Reference : Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, PostADay, SQL, SQL Authority, SQL Optimization, SQL Performance, SQL Query, SQL Server, SQL Tips and Tricks, SQLAuthority News, T SQL, Technology

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• SQLAuthority News – Author Visit Review – TechMela Nepal – March 29-30, 2010

  - by pinaldave

  I was very fortunate to attend TechMela at Kathmandu, Nepal on 29th and 30th of March 2010. I would like to thank Allen Bailochan Tuladhar from Microsoft MDP Nepal for inviting me. Allen is a person with seemingly infinite energy and unlimited passion for Microsoft Technology. If you get an opportunity to spend just one hour with him, you will surely be more enthusiastic with regards to Microsoft Technology. And, I was lucky enough that I was able to spend about a total of 9 days with him in Kathmandu, working along with him in the Tech Community. TechMela Nepal Pinal at TechMela, Nepal TechMela is considered as one of the biggest events in Nepal, having been organized by Microsoft MDP Nepal. This event was attended by around 500 students and hundreds of Tech professionals. The event was handled very professionally and at very large scale. Every minor detail was properly planned and obviously thought out well. There were around 50+ volunteers from MS MDP who were monitoring this event systematically to make sure the event would run as smooth as planned. Attendees in Geek T-Shirts During this event, I was delighted to meet David Lim of Microsoft Singapore. He is very passionate in working for Microsoft Technology, as well as building deep relations with the Community. I was fortunate to spend my entire afternoon with him during the sight-seeing trip. We discussed various MS technologies and their community’s adoption as well as the way how each of us can be a part of the community activity. He also delivered excellent keynotes at the event. I must say that this is one of the most enjoyable keynotes I have ever attended. It was interesting and interactive, and I must say that I had the 70s feelings with all the fonts and graphics. I still remember him saying, “Yeah, I was a student and I know you.” Allen Tuladhar, David Lim, Pinal Dave and Guests After the keynote, everybody cheered when Allen came on stage to talk about the event and to introduce the agenda for the next two days. I must say that Allen is one of the most well-known people in Nepal. I was impressed with his popularity, and to prove this, when he got on the stage he had to wait for a long full minute before he was able to greet “Welcome” while the attendees were clapping and cheering. Technology Panelist at Techmela Kathmandu, Nepal This event was blessed with the top-of-the-top officials of various IT industries, Nepal ministries and the US Embassy. All the prominent personalities were present for panel discussion on the stage. The talk was done on various subjects. Also, the energy level which was set by Allen really echoed in the audience as they asked certain questions on different global as well local IT-related questions. The panel discussion really was discussion instead of usual monologue of one person. Pinal Dave presending at TechMela Kathmandu, Nepal This was a two-day event and my session was on either of the day. I had a great participation from the audience on both days. The place where the event was organized had a capacity of around 500+ audience. Both of my sessions were heavily attended and volunteers did a fabulous job helping the attendees find empty seats or arrange some additional seats. I was overwhelmed with the interaction I have received in the large hall. Attendees were not so shy to express their thoughts, so both the sessions were followed up by top notch one-on-one conversations for a couple of hours. Pinal Dave presending at TechMela Kathmandu, Nepal Pinal Dave presending at TechMela Kathmandu, Nepal Pinal Dave presending at TechMela Kathmandu, Nepal There are many questions that I have received during the event, and many of them can be interesting for all of us here so I will write detailed blog posts on these subjects. I also tried to participate in the gaming activities held at the event, but I felt I was kind of lost even if I was only playing for the very first minutes. This made me realize that I am really getting old for video games. Allen presending at TechMela Kathmandu, Nepal Allen’s session on Digital Photography was very impressive as he demonstrated so many features of the Windows Live Product that at one point I felt he is MVP for Windows Live. In fact, he demonstrated how all the Microsoft products work together to give users an excellent desktop experience; no wonder he is an MVP for Windows Desktop Experience. Pinal Dave presending at TechMela Kathmandu, Nepal Any event has two common dilemmas – food and logistics. However, this event had excellent food and state-of-the-art organization. I was very glad that this two-day event turned out to be one of the most successful events in Nepal. I also noticed that almost all attendees rate their experience as beyond expectation and truly exceptional. Pinal Dave and Allen Bailochan Tuladhar If you ever get invited by Allen in any of his event, I strongly suggest that you drop all your plans and scheduled stuff, and accept his invitation. For sure, the event will be a very memorable one and would be your once-in-a-lifetime experience. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: MVP, Pinal Dave, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, SQLAuthority Author Visit, SQLAuthority News, T SQL, Technology

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• SQLAuthority News – Author Visit Review – TechMela Nepal – March 29-30, 2010

  - by pinaldave

  I was very fortunate to attend TechMela at Kathmandu, Nepal on 29th and 30th of March 2010. I would like to thank Allen Bailochan Tuladhar from Microsoft MDP Nepal for inviting me. Allen is a person with seemingly infinite energy and unlimited passion for Microsoft Technology. If you get an opportunity to spend just one hour with him, you will surely be more enthusiastic with regards to Microsoft Technology. And, I was lucky enough that I was able to spend about a total of 9 days with him in Kathmandu, working along with him in the Tech Community. TechMela Nepal Pinal at TechMela, Nepal TechMela is considered as one of the biggest events in Nepal, having been organized by Microsoft MDP Nepal. This event was attended by around 500 students and hundreds of Tech professionals. The event was handled very professionally and at very large scale. Every minor detail was properly planned and obviously thought out well. There were around 50+ volunteers from MS MDP who were monitoring this event systematically to make sure the event would run as smooth as planned. Attendees in Geek T-Shirts During this event, I was delighted to meet David Lim of Microsoft Singapore. He is very passionate in working for Microsoft Technology, as well as building deep relations with the Community. I was fortunate to spend my entire afternoon with him during the sight-seeing trip. We discussed various MS technologies and their community’s adoption as well as the way how each of us can be a part of the community activity. He also delivered excellent keynotes at the event. I must say that this is one of the most enjoyable keynotes I have ever attended. It was interesting and interactive, and I must say that I had the 70s feelings with all the fonts and graphics. I still remember him saying, “Yeah, I was a student and I know you.” Allen Tuladhar, David Lim, Pinal Dave and Guests After the keynote, everybody cheered when Allen came on stage to talk about the event and to introduce the agenda for the next two days. I must say that Allen is one of the most well-known people in Nepal. I was impressed with his popularity, and to prove this, when he got on the stage he had to wait for a long full minute before he was able to greet “Welcome” while the attendees were clapping and cheering. Technology Panelist at Techmela Kathmandu, Nepal This event was blessed with the top-of-the-top officials of various IT industries, Nepal ministries and the US Embassy. All the prominent personalities were present for panel discussion on the stage. The talk was done on various subjects. Also, the energy level which was set by Allen really echoed in the audience as they asked certain questions on different global as well local IT-related questions. The panel discussion really was discussion instead of usual monologue of one person. Pinal Dave presenting at TechMela Kathmandu, Nepal This was a two-day event and my session was on either of the day. I had a great participation from the audience on both days. The place where the event was organized had a capacity of around 500+ audience. Both of my sessions were heavily attended and volunteers did a fabulous job helping the attendees find empty seats or arrange some additional seats. I was overwhelmed with the interaction I have received in the large hall. Attendees were not so shy to express their thoughts, so both the sessions were followed up by top notch one-on-one conversations for a couple of hours. Pinal Dave presenting at TechMela Kathmandu, Nepal Pinal Dave presenting at TechMela Kathmandu, Nepal There are many questions that I have received during the event, and many of them can be interesting for all of us here so I will write detailed blog posts on these subjects. I also tried to participate in the gaming activities held at the event, but I felt I was kind of lost even if I was only playing for the very first minutes. This made me realize that I am really getting old for video games. Allen presenting at TechMela Kathmandu, Nepal Allen’s session on Digital Photography was very impressive as he demonstrated so many features of the Windows Live Product that at one point I felt he is MVP for Windows Live. In fact, he demonstrated how all the Microsoft products work together to give users an excellent desktop experience; no wonder he is an MVP for Windows Desktop Experience. Pinal Dave presending at TechMela Kathmandu, Nepal Any event has two common dilemmas – food and logistics. However, this event had excellent food and state-of-the-art organization. I was very glad that this two-day event turned out to be one of the most successful events in Nepal. I also noticed that almost all attendees rate their experience as beyond expectation and truly exceptional. Pinal Dave and Allen Bailochan Tuladhar If you ever get invited by Allen in any of his event, I strongly suggest that you drop all your plans and scheduled stuff, and accept his invitation. For sure, the event will be a very memorable one and would be your once-in-a-lifetime experience. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: MVP, Pinal Dave, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, SQLAuthority Author Visit, SQLAuthority News, T SQL, Technology

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• Developer’s Life – Summary of Superhero Articles

  - by Pinal Dave

  Earlier this year, I wrote an article series where I talked about developer’s life and compared it with Superhero. I have got amazing response to this series and I have been receiving quite a lots of email suggesting that I should write more blog post about them. Currently I am not planning to write more blog post but I will soon continue another series. In this blog post, I have summarized the entire series. Let me know if you want me to write about any superhero. I will see what I can do about that hero. Developer’s Life – Every Developer is a Captain America Captain America was first created as a comic book character in the 1940’s as a way to boost morale during World War II.  Aimed at a children’s audience, his legacy faded away when the war ended.  However, he has recently has a major reboot to become a popular movie character that deals with modern issues. Developer’s Life – Every Developer is the Incredible Hulk The Incredible Hulk is possibly one of the scariest superheroes out there.  All superheroes are meant to be “out of this world” and awe-inspiring, but I think most people will agree with I say The Hulk takes this to the next level.  He is the result of an industrial accident, which is scary enough in it’s own right.  Plus, when mild-mannered Bruce Banner is angered, he goes completely out-of-control and transforms into a destructive monster that he cannot control and has no memories of. Developer’s Life – Every Developer is a Wonder Woman We have focused a lot lately on this “superhero series.”  I love fantasy books and movies, and I feel like there is a lot to be learned from them.  As I am writing this series, though, I have noticed that every super hero I write about is a man.  So today, I would like to talk about the major female super hero – Wonder Woman. Developer’s Life – Every Developer is a Harry Potter Harry Potter might not be a superhero in the traditional sense, but I believe he still has a lot to teach us and show us about life as a developer.  If you have been living under a rock for the last 17 years, you might not know that Harry Potter is the main character in an extremely popular series of books and movies documenting the education and tribulation of a young wizard (and his friends). Developer’s Life – Every Developer is Like Transformers Transformers may not be superheroes – they don’t wear capes, they don’t have amazing powers outside of their size and folding ability, they’re not even human (technically).  Part of their enduring popularity is that while we are enjoying over-the-top movies, we are learning about good leadership and strong personal skills. Developer’s Life – Every Developer is a Iron Man Iron Man is another superhero who is not naturally “super,” but relies on his brain (and money) to turn him into a fighting machine.  While traditional superheroes are still popular, a three-movie franchise and incorporation into the new Avengers series shows that Iron Man is popular enough on his own. Developer’s Life – Every Developer is a Sherlock Holmes I have been thinking a lot about how developers are like super heroes, and I have written two blog posts now comparing them to Spiderman and Superman.  I have a lot of love and respect for developers, and I hope that they are enjoying these articles, and others are learning a little bit about the profession.  There is another fictional character who, while not technically asuper hero, is very powerful, and I also think stands as a good example of a developer. That character is Sherlock Holmes.  Sherlock Holmes is a British detective, first made popular at the turn of the 19thcentury by author Sir Arthur Conan Doyle.  The original Sherlock Holmes was a brilliant detective who could solve the most mind-boggling crime through simple observations and deduction. Developer’s Life – Every Developer is a Chhota Bheem Chhota Bheem is a cartoon character that is extremely popular where I live.  He is my daughter’s favorite characters.  I like to say that children love Chhota Bheem more than their parents – it is lucky for us he is not real!  Children love Chhota Bheem because he is the absolute “good guy.”  He is smart, loyal, and strong.  He and his friends live in Dholakpur and fight off their many enemies – and always win – in every episode.  In each episode, they learn something about friendship, bravery, and being kind to others.  Chhota Bheem is a good role model for children, and I think that he is a good role model for developers are well. Developer’s Life – Every Developer is a Batman Batman is one of the darkest superheroes in the fantasy canon.  He does not come to his powers through any sort of magical coincidence or radioactive insect, but through a lot of psychological scarring caused by witnessing the death of his parents.  Despite his dark back story, he possesses a lot of admirable abilities that I feel bear comparison to developers. Developer’s Life – Every Developer is a Superman I enjoyed comparing developers to Spiderman so much, that I have decided to continue the trend and encourage some of my favorite people (developers) with another favorite superhero – Superman.  Superman is probably the most famous superhero – and one of the most inspiring. Developer’s Life – Every Developer is a Spiderman I have to admit, Spiderman is my favorite superhero.  The most recent movie recently was released in theaters, so it has been at the front of my mind for some time. Spiderman was my favorite superhero even before the latest movie came out, but of course I took my whole family to see the movie as soon as I could!  Every one of us loved it, including my daughter.  We all left the movie thinking how great it would be to be Spiderman.  So, with that in mind, I started thinking about how we are like Spiderman in our everyday lives, especially developers. I would like to know which Superhero is your favorite hero! Reference: Pinal Dave (http://blog.SQLAuthority.com)Filed under: PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, T SQL Tagged: Developer, Superhero

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• SQLAuthority News – A Successful Community TechDays at Ahmedabad – December 11, 2010

  - by pinaldave

  We recently had one of the best community events in Ahmedabad. We were fortunate that we had SQL Experts from around the world to have presented at this event. This gathering was very special because besides Jacob Sebastian and myself, we had two other speakers traveling all the way from Florida (Rushabh Mehta) and Bangalore (Vinod Kumar).There were a total of nearly 170 attendees and the event was blast. Here are the details of the event. Pinal Dave Presenting at Community Tech Days On the day of the event, it seemed to be the coldest day in Ahmedabad but I was glad to see hundreds of people waiting for the doors to be opened some hours before. We started the day with hot coffee and cookies. Yes, food first; and it was right after my keynote. I could clearly see that the coffee did some magic right away; the hall was almost full after the coffee break. Jacob Sebastian Presenting at Community Tech Days Jacob Sebastian, an SQL Server MVP and a close friend of mine, had an unusual job of surprising everybody with an innovative topic accompanied with lots of question-and-answer portions. That’s definitely one thing to love Jacob, that is, the novelty of the subject. His presentation was entitled “Best Database Practices for the .Net”; it really created magic on the crowd. Pinal Dave Presenting at Community Tech Days Next to Jacob Sebastian, I presented “Best Database Practices for the SharePoint”. It was really fun to present Database with the perspective of the database itself. The main highlight of my presentation was when I talked about how one can speed up the database performance by 40% for SharePoint in just 40 seconds. It was fun because the most important thing was to convince people to use the recommendation as soon as they walk out of the session. It was really amusing and the response of the participants was remarkable. Pinal Dave Presenting at Community Tech Days My session was followed by the most-awaited session of the day: that of Rushabh Mehta. He is an international BI expert who traveled all the way from Florida to present “Self Service BI” session. This session was funny and truly interesting. In fact, no one knew BI could be this much entertaining and fascinating. Rushabh has an appealing style of presenting the session; he instantly got very much interaction from the audience. Rushabh Mehta Presenting at Community Tech Days We had a networking lunch break in-between, when we talked about many various topics. It is always interesting to get in touch with the Community and feel a part of it. I had a wonderful time during the break. Vinod Kumar Presenting at Community Tech Days After lunch was apparently the most difficult session for the presenter as during this time, many people started to fall sleep and get dizzy. This spot was requested by Microsoft SQL Server Evangelist Vinod Kumar himself. During our discussion he suggested that if he gets this slot he would make sure people are up and more interactive than during the morning session. Just like always, this session was one of the best sessions ever. Vinod is true to his word as he presented the subject of “Time Management for Developer”. This session was the biggest hit in the event because the subject was instilled in the mind of every participant. Vinod Kumar Presenting at Community Tech Days Vinod’s session was followed by his own small session. Due to “insistent public demand”, he presented an interesting subject, “Tricks and Tips of SQL Server“. In 20 minutes he has done another awesome job and all attendees wanted more of the tricks. Just as usual he promised to do that next time for us. Vinod’s session was succeeded by Prabhjot Singh Bakshi’s session. He presented an appealing Silverlight concept. Just the same, he did a great job and people cheered him. Prabhjot Presenting at Community Tech Days We had a special invited speaker, Dhananjay Kumar, traveling all the way from Pune. He always supports our cause to help the Community in empowering participants. He presented the topic about Win7 Mobile and SharePoint integration. This was something many did not even expect to be possible. Kudos to Dhananjay for doing a great job. Dhananjay Kumar Presenting at Community Tech Days All in all, this event was one of the best in the Community Tech Days series in Ahmedabad. We were fortunate that legends from the all over the world were present here to present to the Community. I’d say never underestimate the power of the Community and its influence over the direction of the technology. Vinod Kumar Presenting trophy to Pinal Dave Vinod Kumar Presenting trophy to Pinal Dave This event was a very special gathering to me personally because of your support to the vibrant Community. The following awards were won for last year’s performance: Ahmedabad SQL Server User Group (President: Jacob Sebastian; Leader: Pinal Dave) – Best Tier 2 User Group Best Development Community Individual Contributor – Pinal Dave Speakers I was very glad to receive the award for our entire Community. Attendees at Community Tech Days I want to say thanks to Rushabh Mehta, Vinod Kumar and Dhananjay Kumar for visiting the city and presenting various technology topics in Community Tech Days. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: MVP, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, SQLAuthority Author Visit, SQLAuthority News, T SQL, Technology

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• SQL SERVER – Simple Example of Snapshot Isolation – Reduce the Blocking Transactions

  - by pinaldave

  To learn any technology and move to a more advanced level, it is very important to understand the fundamentals of the subject first. Today, we will be talking about something which has been quite introduced a long time ago but not properly explored when it comes to the isolation level. Snapshot Isolation was introduced in SQL Server in 2005. However, the reality is that there are still many software shops which are using the SQL Server 2000, and therefore cannot be able to maintain the Snapshot Isolation. Many software shops have upgraded to the later version of the SQL Server, but their respective developers have not spend enough time to upgrade themselves with the latest technology. “It works!” is a very common answer of many when they are asked about utilizing the new technology, instead of backward compatibility commands. In one of the recent consultation project, I had same experience when developers have “heard about it” but have no idea about snapshot isolation. They were thinking it is the same as Snapshot Replication – which is plain wrong. This is the same demo I am including here which I have created for them. In Snapshot Isolation, the updated row versions for each transaction are maintained in TempDB. Once a transaction has begun, it ignores all the newer rows inserted or updated in the table. Let us examine this example which shows the simple demonstration. This transaction works on optimistic concurrency model. Since reading a certain transaction does not block writing transaction, it also does not block the reading transaction, which reduced the blocking. First, enable database to work with Snapshot Isolation. Additionally, check the existing values in the table from HumanResources.Shift. ALTER DATABASE AdventureWorks SET ALLOW_SNAPSHOT_ISOLATION ON GO SELECT ModifiedDate FROM HumanResources.Shift GO Now, we will need two different sessions to prove this example. First Session: Set Transaction level isolation to snapshot and begin the transaction. Update the column “ModifiedDate” to today’s date. -- Session 1 SET TRANSACTION ISOLATION LEVEL SNAPSHOT BEGIN TRAN UPDATE HumanResources.Shift SET ModifiedDate = GETDATE() GO Please note that we have not yet been committed to the transaction. Now, open the second session and run the following “SELECT” statement. Then, check the values of the table. Please pay attention on setting the Isolation level for the second one as “Snapshot” at the same time when we already start the transaction using BEGIN TRAN. -- Session 2 SET TRANSACTION ISOLATION LEVEL SNAPSHOT BEGIN TRAN SELECT ModifiedDate FROM HumanResources.Shift GO You will notice that the values in the table are still original values. They have not been modified yet. Once again, go back to session 1 and begin the transaction. -- Session 1 COMMIT After that, go back to Session 2 and see the values of the table. -- Session 2 SELECT ModifiedDate FROM HumanResources.Shift GO You will notice that the values are yet not changed and they are still the same old values which were there right in the beginning of the session. Now, let us commit the transaction in the session 2. Once committed, run the same SELECT statement once more and see what the result is. -- Session 2 COMMIT SELECT ModifiedDate FROM HumanResources.Shift GO You will notice that it now reflects the new updated value. I hope that this example is clear enough as it would give you good idea how the Snapshot Isolation level works. There is much more to write about an extra level, READ_COMMITTED_SNAPSHOT, which we will be discussing in another post soon. If you wish to use this transaction’s Isolation level in your production database, I would appreciate your comments about their performance on your servers. I have included here the complete script used in this example for your quick reference. ALTER DATABASE AdventureWorks SET ALLOW_SNAPSHOT_ISOLATION ON GO SELECT ModifiedDate FROM HumanResources.Shift GO -- Session 1 SET TRANSACTION ISOLATION LEVEL SNAPSHOT BEGIN TRAN UPDATE HumanResources.Shift SET ModifiedDate = GETDATE() GO -- Session 2 SET TRANSACTION ISOLATION LEVEL SNAPSHOT BEGIN TRAN SELECT ModifiedDate FROM HumanResources.Shift GO -- Session 1 COMMIT -- Session 2 SELECT ModifiedDate FROM HumanResources.Shift GO -- Session 2 COMMIT SELECT ModifiedDate FROM HumanResources.Shift GO Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: Pinal Dave, SQL, SQL Authority, SQL Performance, SQL Query, SQL Scripts, SQL Server, SQL Tips and Tricks, T SQL, Technology Tagged: Transaction Isolation

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