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• SQLAuthority News – #TechEdIn – TechEd India 2012 Memories and Photos

  - by pinaldave

  TechEd India 2012 was held in Bangalore last March 21 to 23, 2012. Just like every year, this event is bigger, grander and inspiring. Pinal Dave at TechEd India 2012 Family Event Every single year, TechEd is a special affair for my entire family.  Four months before the start of TechEd, I usually start to build the mental image of the event. I start to think  about various things. For the most part, what excites me most is presenting a session and meeting friends. Seriously, I start thinking about presenting my session 4 months earlier than the event!  I work on my presentation day and night. I want to make sure that what I present is accurate and that I have experienced it firsthand. My wife and my daughter also contribute to my efforts. For us, TechEd is a family event, and the two of them feel equally responsible as well. They give up their family time so I can bring out the best content for the Community. Pinal, Shaivi and Nupur at TechEd India 2012 Guinea Pigs (My Experiment Victims) I do not rehearse my session, ever. However, I test my demo almost every single day till the last moment that I have to present it already. I sometimes go over the demo more than 2-3 times a day even though the event is more than a month away. I have two “guinea pigs”: 1) Nupur Dave and 2) Vinod Kumar. When I am at home, I present my demos to my wife Nupur. At times I feel that people often backup their demo, but in my case, I have backup demo presenters. In the office during lunch time, I present the demos to Vinod. I am sure he can walk my demos easily with eyes closed. Pinal and Vinod at TechEd India 2012 My Sessions I’ve been determined to present my sessions in a real and practical manner. I prefer to present the subject that I myself would be eager to attend to and sit through if I were an audience. Just keeping that principle in mind, I have created two sessions this year. SQL Server Misconception and Resolution Pinal and Vinod at TechEd India 2012 We believe all kinds of stuff – that the earth is flat, or that the forbidden fruit is apple, or that the big bang theory explains the origin of the universe, and so many other things. Just like these, we have plenty of misconceptions in SQL Server as well. I have had this dream of co-presenting a session with Vinod Kumar for the past 3 years. I have been asking him every year if we could present a session together, but we never got it to work out, until this year came. Fortunately, we got a chance to stand on the same stage and present a single subject.  I believe that Vinod Kumar and I have an excellent synergy when we are working together. We know each other’s strengths and weakness. We know when the other person will speak and when he will keep quiet. The reason behind this synergy is that we have worked on 2 Video Learning Courses (SQL Server Indexes and SQL Server Questions and Answers) and authored 1 book (SQL Server Questions and Answers) together. Crowd Outside Session Hall This session was inspired from the “Laurel and Hardy” show so we performed a role-playing of those famous characters. We had an excellent time at the stage and, for sure, the audience had a wonderful time, too. We had an extremely large audience for this session and had a great time interacting with them. Speed Up! – Parallel Processes and Unparalleled Performance Pinal Dave at TechEd India 2012 I wanted to approach this session at level 400 and I was very determined to do so. The biggest challenge I had was that this was a total of 60 minutes of session and the audience profile was very generic. I had to present at level 100 as well at 400. I worked hard to tune up these demos. I wanted to make sure that my messages would land perfectly to the minds of the attendees, and when they walk out of the session, they could use the knowledge I shared on their servers. After the session, I felt an extreme satisfaction as I received lots of positive feedback at the event. At one point, so many people rushed towards me that I was a bit scared that the stage might break and someone would get injured. Fortunately, nothing like that happened and I was able to shake hands with everybody. Pinal Dave at TechEd India 2012 Crowd rushing to Pinal at TechEd India 2012 Networking This is one of the primary reasons many of us visit the annual TechEd event. I had a fantastic time meeting SQL Server enthusiasts. Well, it was a terrific time meeting old friends, user group members, MVPs and SQL Enthusiasts. I have taken many photographs with lots of people, but I have received a very few back. If you are reading this blog and have a photo of us at the event, would you please send it to me so I could keep it in my memory lane? SQL Track Speaker: Jacob and Pinal at TechEd India 2012 SQL Community: Pinal, Tejas, Nakul, Jacob, Balmukund, Manas, Sudeepta, Sahal at TechEd India 2012 Star Speakers: Amit and Balmukund at TechEd India 2012 TechED Rockstars: Nakul, Tejas and Pinal at TechEd India 2012 I guess TechEd is a mix of family affair and culture for me! Hamara TechEd (Our TechEd) Please tell me which photo you like the most! Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, SQLAuthority Author Visit, SQLAuthority News, SQLServer, T SQL, Technology Tagged: TechEd, TechEdIn

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• Big Data – Operational Databases Supporting Big Data – RDBMS and NoSQL – Day 12 of 21

  - by Pinal Dave

  In yesterday’s blog post we learned the importance of the Cloud in the Big Data Story. In this article we will understand the role of Operational Databases Supporting Big Data Story. Even though we keep on talking about Big Data architecture, it is extremely crucial to understand that Big Data system can’t just exist in the isolation of itself. There are many needs of the business can only be fully filled with the help of the operational databases. Just having a system which can analysis big data may not solve every single data problem. Real World Example Think about this way, you are using Facebook and you have just updated your information about the current relationship status. In the next few seconds the same information is also reflected in the timeline of your partner as well as a few of the immediate friends. After a while you will notice that the same information is now also available to your remote friends. Later on when someone searches for all the relationship changes with their friends your change of the relationship will also show up in the same list. Now here is the question – do you think Big Data architecture is doing every single of these changes? Do you think that the immediate reflection of your relationship changes with your family member is also because of the technology used in Big Data. Actually the answer is Facebook uses MySQL to do various updates in the timeline as well as various events we do on their homepage. It is really difficult to part from the operational databases in any real world business. Now we will see a few of the examples of the operational databases. Relational Databases (This blog post) NoSQL Databases (This blog post) Key-Value Pair Databases (Tomorrow’s post) Document Databases (Tomorrow’s post) Columnar Databases (The Day After’s post) Graph Databases (The Day After’s post) Spatial Databases (The Day After’s post) Relational Databases We have earlier discussed about the RDBMS role in the Big Data’s story in detail so we will not cover it extensively over here. Relational Database is pretty much everywhere in most of the businesses which are here for many years. The importance and existence of the relational database are always going to be there as long as there are meaningful structured data around. There are many different kinds of relational databases for example Oracle, SQL Server, MySQL and many others. If you are looking for Open Source and widely accepted database, I suggest to try MySQL as that has been very popular in the last few years. I also suggest you to try out PostgreSQL as well. Besides many other essential qualities PostgreeSQL have very interesting licensing policies. PostgreSQL licenses allow modifications and distribution of the application in open or closed (source) form. One can make any modifications and can keep it private as well as well contribute to the community. I believe this one quality makes it much more interesting to use as well it will play very important role in future. Nonrelational Databases (NOSQL) We have also covered Nonrelational Dabases in earlier blog posts. NoSQL actually stands for Not Only SQL Databases. There are plenty of NoSQL databases out in the market and selecting the right one is always very challenging. Here are few of the properties which are very essential to consider when selecting the right NoSQL database for operational purpose. Data and Query Model Persistence of Data and Design Eventual Consistency Scalability Though above all of the properties are interesting to have in any NoSQL database but the one which most attracts to me is Eventual Consistency. Eventual Consistency RDBMS uses ACID (Atomicity, Consistency, Isolation, Durability) as a key mechanism for ensuring the data consistency, whereas NonRelational DBMS uses BASE for the same purpose. Base stands for Basically Available, Soft state and Eventual consistency. Eventual consistency is widely deployed in distributed systems. It is a consistency model used in distributed computing which expects unexpected often. In large distributed system, there are always various nodes joining and various nodes being removed as they are often using commodity servers. This happens either intentionally or accidentally. Even though one or more nodes are down, it is expected that entire system still functions normally. Applications should be able to do various updates as well as retrieval of the data successfully without any issue. Additionally, this also means that system is expected to return the same updated data anytime from all the functioning nodes. Irrespective of when any node is joining the system, if it is marked to hold some data it should contain the same updated data eventually. As per Wikipedia - Eventual consistency is a consistency model used in distributed computing that informally guarantees that, if no new updates are made to a given data item, eventually all accesses to that item will return the last updated value. In other words -  Informally, if no additional updates are made to a given data item, all reads to that item will eventually return the same value. Tomorrow In tomorrow’s blog post we will discuss about various other Operational Databases supporting Big Data. 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 – Buzz Words: What is Hadoop – Day 6 of 21

  - by Pinal Dave

  In yesterday’s blog post we learned what is NoSQL. In this article we will take a quick look at one of the four most important buzz words which goes around Big Data – Hadoop. What is Hadoop? Apache Hadoop is an open-source, free and Java based software framework offers a powerful distributed platform to store and manage Big Data. It is licensed under an Apache V2 license. It runs applications on large clusters of commodity hardware and it processes thousands of terabytes of data on thousands of the nodes. Hadoop is inspired from Google’s MapReduce and Google File System (GFS) papers. The major advantage of Hadoop framework is that it provides reliability and high availability. What are the core components of Hadoop? There are two major components of the Hadoop framework and both fo them does two of the important task for it. Hadoop MapReduce is the method to split a larger data problem into smaller chunk and distribute it to many different commodity servers. Each server have their own set of resources and they have processed them locally. Once the commodity server has processed the data they send it back collectively to main server. This is effectively a process where we process large data effectively and efficiently. (We will understand this in tomorrow’s blog post). Hadoop Distributed File System (HDFS) is a virtual file system. There is a big difference between any other file system and Hadoop. When we move a file on HDFS, it is automatically split into many small pieces. These small chunks of the file are replicated and stored on other servers (usually 3) for the fault tolerance or high availability. (We will understand this in the day after tomorrow’s blog post). Besides above two core components Hadoop project also contains following modules as well. Hadoop Common: Common utilities for the other Hadoop modules Hadoop Yarn: A framework for job scheduling and cluster resource management There are a few other projects (like Pig, Hive) related to above Hadoop as well which we will gradually explore in later blog posts. A Multi-node Hadoop Cluster Architecture Now let us quickly see the architecture of the a multi-node Hadoop cluster. A small Hadoop cluster includes a single master node and multiple worker or slave node. As discussed earlier, the entire cluster contains two layers. One of the layer of MapReduce Layer and another is of HDFC Layer. Each of these layer have its own relevant component. The master node consists of a JobTracker, TaskTracker, NameNode and DataNode. A slave or worker node consists of a DataNode and TaskTracker. It is also possible that slave node or worker node is only data or compute node. The matter of the fact that is the key feature of the Hadoop. In this introductory blog post we will stop here while describing the architecture of Hadoop. In a future blog post of this 31 day series we will explore various components of Hadoop Architecture in Detail. Why Use Hadoop? There are many advantages of using Hadoop. Let me quickly list them over here: Robust and Scalable – We can add new nodes as needed as well modify them. Affordable and Cost Effective – We do not need any special hardware for running Hadoop. We can just use commodity server. Adaptive and Flexible – Hadoop is built keeping in mind that it will handle structured and unstructured data. Highly Available and Fault Tolerant – When a node fails, the Hadoop framework automatically fails over to another node. Why Hadoop is named as Hadoop? In year 2005 Hadoop was created by Doug Cutting and Mike Cafarella while working at Yahoo. Doug Cutting named Hadoop after his son’s toy elephant. Tomorrow In tomorrow’s blog post we will discuss Buzz Word – MapReduce. 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 – Number-Crunching with SQL Server – Exceed the Functionality of Excel

  - by Pinal Dave

  Imagine this. Your users have developed an Excel spreadsheet that extracts data from your SQL Server database, manipulates that data through the use of Excel formulas and, possibly, some VBA code which is then used to calculate P&L, hedging requirements or even risk numbers. Management comes to you and tells you that they need to get rid of the spreadsheet and that the results of the spreadsheet calculations need to be persisted on the database. SQL Server has a very small set of functions for analyzing data. Excel has hundreds of functions for analyzing data, with many of them focused on specific financial and statistical calculations. Is it even remotely possible that you can use SQL Server to replace the complex calculations being done in a spreadsheet? Westclintech has developed a library of functions that match or exceed the functionality of Excel’s functions and contains many functions that are not available in EXCEL. Their XLeratorDB library of functions contains over 700 functions that can be incorporated into T-SQL statements. XLeratorDB takes advantage of the SQL CLR architecture introduced in SQL Server 2005. SQL CLR permits managed code to be compiled into the database and run alongside built-in SQL Server functions like COUNT or SUM. The Westclintech developers have taken advantage of this architecture to bring robust analytical functions to the database. In our hypothetical spreadsheet, let’s assume that our users are using the YIELD function and that the data are extracted from a table in our database called BONDS. Here’s what the spreadsheet might look like. We go to column G and see that it contains the following formula. Obviously, SQL Server does not offer a native YIELD function. However, with XLeratorDB we can replicate this calculation in SQL Server with the following statement: SELECT *, wct.YIELD(CAST(GETDATE() AS date),Maturity,Rate,Price,100,Frequency,Basis) AS YIELD FROM BONDS This produces the following result. This illustrates one of the best features about XLeratorDB; it is so easy to use. Since I knew that the spreadsheet was using the YIELD function I could use the same function with the same calling structure to do the calculation in SQL Server. I didn’t need to know anything at all about the mechanics of calculating the yield on a bond. It was pretty close to cut and paste. In fact, that’s one way to construct the SQL. Just copy the function call from the cell in the spreadsheet and paste it into SMS and change the cell references to column names. I built the SQL for this query by starting with this. SELECT * ,YIELD(TODAY(),B2,C2,D2,100,E2,F2) FROM BONDS I then changed the cell references to column names. SELECT * --,YIELD(TODAY(),B2,C2,D2,100,E2,F2) ,YIELD(TODAY(),Maturity,Rate,Price,100,Frequency,Basis) FROM BONDS Finally, I replicated the TODAY() function using GETDATE() and added the schema name to the function name. SELECT * --,YIELD(TODAY(),B2,C2,D2,100,E2,F2) --,YIELD(TODAY(),Maturity,Rate,Price,100,Frequency,Basis) ,wct.YIELD(GETDATE(),Maturity,Rate,Price,100,Frequency,Basis) FROM BONDS Then I am able to execute the statement returning the results seen above. The XLeratorDB libraries are heavy on financial, statistical, and mathematical functions. Where there is an analog to an Excel function, the XLeratorDB function uses the same naming conventions and calling structure as the Excel function, but there are also hundreds of additional functions for SQL Server that are not found in Excel. You can find the functions by opening Object Explorer in SQL Server Management Studio (SSMS) and expanding the Programmability folder under the database where the functions have been installed. The  Functions folder expands to show 3 sub-folders: Table-valued Functions; Scalar-valued functions, Aggregate Functions, and System Functions. You can expand any of the first three folders to see the XLeratorDB functions. Since the wct.YIELD function is a scalar function, we will open the Scalar-valued Functions folder, scroll down to the wct.YIELD function and and click the plus sign (+) to display the input parameters. The functions are also Intellisense-enabled, with the input parameters displayed directly in the query tab. The Westclintech website contains documentation for all the functions including examples that can be copied directly into a query window and executed. There are also more one hundred articles on the site which go into more detail about how some of the functions work and demonstrate some of the extensive business processes that can be done in SQL Server using XLeratorDB functions and some T-SQL. XLeratorDB is organized into libraries: finance, statistics; math; strings; engineering; and financial options. There is also a windowing library for SQL Server 2005, 2008, and 2012 which provides functions for calculating things like running and moving averages (which were introduced in SQL Server 2012), FIFO inventory calculations, financial ratios and more, without having to use triangular joins. To get started you can download the XLeratorDB 15-day free trial from the Westclintech web site. It is a fully-functioning, unrestricted version of the software. If you need more than 15 days to evaluate the software, you can simply download another 15-day free trial. XLeratorDB is an easy and cost-effective way to start adding sophisticated data analysis to your SQL Server database without having to know anything more than T-SQL. Get XLeratorDB Today and Now! Reference: Pinal Dave (http://blog.sqlauthority.com)Filed under: PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, T SQL Tagged: Excel

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• SQL SERVER – What is Incremental Statistics? – Performance improvements in SQL Server 2014 – Part 1

  - by Pinal Dave

  This is the first part of the series Incremental Statistics. Here is the index of the complete series. What is Incremental Statistics? – Performance improvements in SQL Server 2014 – Part 1 Simple Example of Incremental Statistics – Performance improvements in SQL Server 2014 – Part 2 DMV to Identify Incremental Statistics – Performance improvements in SQL Server 2014 – Part 3 Statistics are considered one of the most important aspects of SQL Server Performance Tuning. You might have often heard the phrase, with related to performance tuning. “Update Statistics before you take any other steps to tune performance”. Honestly, I have said above statement many times and many times, I have personally updated statistics before I start to do any performance tuning exercise. You may agree or disagree to the point, but there is no denial that Statistics play an extremely vital role in the performance tuning. SQL Server 2014 has a new feature called Incremental Statistics. I have been playing with this feature for quite a while and I find that very interesting. After spending some time with this feature, I decided to write about this subject over here. New in SQL Server 2014 – Incremental Statistics Well, it seems like lots of people wants to start using SQL Server 2014′s new feature of Incremetnal Statistics. However, let us understand what actually this feature does and how it can help. I will try to simplify this feature first before I start working on the demo code. Code for all versions of SQL Server Here is the code which you can execute on all versions of SQL Server and it will update the statistics of your table. The keyword which you should pay attention is WITH FULLSCAN. It will scan the entire table and build brand new statistics for you which your SQL Server Performance Tuning engine can use for better estimation of your execution plan. UPDATE STATISTICS TableName(StatisticsName) WITH FULLSCAN Who should learn about this? Why? If you are using partitions in your database, you should consider about implementing this feature. Otherwise, this feature is pretty much not applicable to you. Well, if you are using single partition and your table data is in a single place, you still have to update your statistics the same way you have been doing. If you are using multiple partitions, this may be a very useful feature for you. In most cases, users have multiple partitions because they have lots of data in their table. Each partition will have data which belongs to itself. Now it is very common that each partition are populated separately in SQL Server. Real World Example For example, if your table contains data which is related to sales, you will have plenty of entries in your table. It will be a good idea to divide the partition into multiple filegroups for example, you can divide this table into 3 semesters or 4 quarters or even 12 months. Let us assume that we have divided our table into 12 different partitions. Now for the month of January, our first partition will be populated and for the month of February our second partition will be populated. Now assume, that you have plenty of the data in your first and second partition. Now the month of March has just started and your third partition has started to populate. Due to some reason, if you want to update your statistics, what will you do? In SQL Server 2012 and earlier version You will just use the code of WITH FULLSCAN and update the entire table. That means even though you have only data in third partition you will still update the entire table. This will be VERY resource intensive process as you will be updating the statistics of the partition 1 and 2 where data has not changed at all. In SQL Server 2014 You will just update the partition of Partition 3. There is a special syntax where you can now specify which partition you want to update now. The impact of this is that it is smartly merging the new data with old statistics and update the entire statistics without doing FULLSCAN of your entire table. This has a huge impact on performance. Remember that the new feature in SQL Server 2014 does not change anything besides the capability to update a single partition. However, there is one feature which is indeed attractive. Previously, when table data were changed 20% at that time, statistics update were triggered. However, now the same threshold is applicable to a single partition. That means if your partition faces 20% data, change it will also trigger partition level statistics update which, when merged to your final statistics will give you better performance. In summary If you are not using a partition, this feature is not applicable to you. If you are using a partition, this feature can be very helpful to you. Tomorrow: We will see working code of SQL Server 2014 Incremental Statistics. Reference: Pinal Dave (http://blog.sqlauthority.com)Filed under: PostADay, SQL, SQL Authority, SQL Performance, SQL Query, SQL Server, SQL Tips and Tricks, T SQL Tagged: SQL Statistics, Statistics

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• SQL SERVER – Weekly Series – Memory Lane – #053 – Final Post in Series

  - by Pinal Dave

  It has been a fantastic journey to write memory lane series for an entire year. This series gave me the opportunity to go back and see what I have contributed to this blog throughout the last 7 years. This was indeed fantastic series as this provided me the opportunity to witness how technology has grown throughout the year and how I have progressed in my career while writing this blog post. This series was indeed fantastic experience readers as many joined during the last few years and were not sure what they have missed in recent years. Let us continue with the final episode of the Memory Lane Series. Here is the list of selected articles of SQLAuthority.com across all these years. Instead of just listing all the articles I have selected a few of my most favorite articles and have listed them here with additional notes below it. Let me know which one of the following is your favorite article from memory lane. 2007 Get Current User – Get Logged In User Here is the straight script which list logged in SQL Server users. Disable All Triggers on a Database – Disable All Triggers on All Servers Question : How to disable all the triggers for a database? Additionally, how to disable all the triggers for all servers? For answer execute the script in the blog post. Importance of Master Database for SQL Server Startup I have received following questions many times. I will list all the questions here and answer them together. What is the purpose of Master database? Should our backup Master database? Which database is must have database for SQL Server for startup? Which are the default system database created when SQL Server 2005 is installed for the first time? What happens if Master database is corrupted? Answers to all of the questions are very much related. 2008 DECLARE Multiple Variables in One Statement SQL Server is a great product and it has many features which are very unique to SQL Server. Regarding feature of SQL Server where multiple variable can be declared in one statement, it is absolutely possible to do. 2009 How to Enable Index – How to Disable Index – Incorrect syntax near ‘ENABLE’ Many times I have seen that the index is disabled when there is a large update operation on the table. Bulk insert of very large file updates in any table using SSIS is usually preceded by disabling the index and followed by enabling the index. I have seen many developers running the following query to disable the index. 2010 List of all the Views from Database Many emails I received suggesting that they have hundreds of the view and now have no clue what is going on and how many of them have indexes and how many does not have an index. Some even asked me if there is any way they can get a list of the views with the property of Index along with it. Here is the quick script which does exactly the same. You can also include many other columns from the same view. Minimum Maximum Memory – Server Memory Options I was recently reading about SQL Server Memory Options over here. While reading this one line really caught my attention is minimum value allowed for maximum memory options. The default setting for min server memory is 0, and the default setting for max server memory is 2147483647. The minimum amount of memory you can specify for max server memory is 16 megabytes (MB). 2011 Fundamentals of Columnstore Index There are two kinds of storage in a database. Row Store and Column Store. Row store does exactly as the name suggests – stores rows of data on a page – and column store stores all the data in a column on the same page. These columns are much easier to search – instead of a query searching all the data in an entire row whether the data are relevant or not, column store queries need only to search a much lesser number of the columns. How to Ignore Columnstore Index Usage in Query In summary the question in simple words “How can we ignore using the column store index in selective queries?” Very interesting question – you can use I can understand there may be the cases when the column store index is not ideal and needs to be ignored the same. You can use the query hint IGNORE_NONCLUSTERED_COLUMNSTORE_INDEX to ignore the column store index. The SQL Server Engine will use any other index which is best after ignoring the column store index. 2012 Storing Variable Values in Temporary Array or Temporary List SQL Server does not support arrays or a dynamic length storage mechanism like list. Absolutely there are some clever workarounds and few extra-ordinary solutions but everybody can;t come up with such solution. Additionally, sometime the requirements are very simple that doing extraordinary coding is not required. Here is the simple case. Move Database Files MDF and LDF to Another Location It is not common to keep the Database on the same location where OS is installed. Usually Database files are in SAN, Separate Disk Array or on SSDs. This is done usually for performance reason and manageability perspective. Now the challenges comes up when database which was installed at not preferred default location and needs to move to a different location. Here is the quick tutorial how you can do it. UNION ALL and ORDER BY – How to Order Table Separately While Using UNION ALL If your requirement is such that you want your top and bottom query of the UNION resultset independently sorted but in the same result set you can add an additional static column and order by that column. Let us re-create the same scenario. Copy Data from One Table to Another Table – SQL in Sixty Seconds #031 – Video http://www.youtube.com/watch?v=FVWIA-ACMNo Reference: Pinal Dave (http://blog.sqlauthority.com)Filed under: Memory Lane, PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology

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• Big Data – Buzz Words: What is HDFS – Day 8 of 21

  - by Pinal Dave

  In yesterday’s blog post we learned what is MapReduce. In this article we will take a quick look at one of the four most important buzz words which goes around Big Data – HDFS. What is HDFS ? HDFS stands for Hadoop Distributed File System and it is a primary storage system used by Hadoop. It provides high performance access to data across Hadoop clusters. It is usually deployed on low-cost commodity hardware. In commodity hardware deployment server failures are very common. Due to the same reason HDFS is built to have high fault tolerance. The data transfer rate between compute nodes in HDFS is very high, which leads to reduced risk of failure. HDFS creates smaller pieces of the big data and distributes it on different nodes. It also copies each smaller piece to multiple times on different nodes. Hence when any node with the data crashes the system is automatically able to use the data from a different node and continue the process. This is the key feature of the HDFS system. Architecture of HDFS The architecture of the HDFS is master/slave architecture. An HDFS cluster always consists of single NameNode. This single NameNode is a master server and it manages the file system as well regulates access to various files. In additional to NameNode there are multiple DataNodes. There is always one DataNode for each data server. In HDFS a big file is split into one or more blocks and those blocks are stored in a set of DataNodes. The primary task of the NameNode is to open, close or rename files and directory and regulate access to the file system, whereas the primary task of the DataNode is read and write to the file systems. DataNode is also responsible for the creation, deletion or replication of the data based on the instruction from NameNode. In reality, NameNode and DataNode are software designed to run on commodity machine build in Java language. Visual Representation of HDFS Architecture Let us understand how HDFS works with the help of the diagram. Client APP or HDFS Client connects to NameSpace as well as DataNode. Client App access to the DataNode is regulated by NameSpace Node. NameSpace Node allows Client App to connect to the DataNode based by allowing the connection to the DataNode directly. A big data file is divided into multiple data blocks (let us assume that those data chunks are A,B,C and D. Client App will later on write data blocks directly to the DataNode. Client App does not have to directly write to all the node. It just has to write to any one of the node and NameNode will decide on which other DataNode it will have to replicate the data. In our example Client App directly writes to DataNode 1 and detained 3. However, data chunks are automatically replicated to other nodes. All the information like in which DataNode which data block is placed is written back to NameNode. High Availability During Disaster Now as multiple DataNode have same data blocks in the case of any DataNode which faces the disaster, the entire process will continue as other DataNode will assume the role to serve the specific data block which was on the failed node. This system provides very high tolerance to disaster and provides high availability. If you notice there is only single NameNode in our architecture. If that node fails our entire Hadoop Application will stop performing as it is a single node where we store all the metadata. As this node is very critical, it is usually replicated on another clustered as well as on another data rack. Though, that replicated node is not operational in architecture, it has all the necessary data to perform the task of the NameNode in the case of the NameNode fails. The entire Hadoop architecture is built to function smoothly even there are node failures or hardware malfunction. It is built on the simple concept that data is so big it is impossible to have come up with a single piece of the hardware which can manage it properly. We need lots of commodity (cheap) hardware to manage our big data and hardware failure is part of the commodity servers. To reduce the impact of hardware failure Hadoop architecture is built to overcome the limitation of the non-functioning hardware. Tomorrow In tomorrow’s blog post we will discuss the importance of the relational database in Big Data. 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 – ?Finding Out What Changed in a Deleted Database – Notes from the Field #041

  - by Pinal Dave

  [Note from Pinal]: This is a 41th episode of Notes from the Field series. The real world is full of challenges. When we are reading theory or book, we sometimes do not realize how real world reacts works and that is why we have the series notes from the field, which is extremely popular with developers and DBA. Let us talk about interesting problem of how to figure out what has changed in the DELETED database. Well, you think I am just throwing the words but in reality this kind of problems are making our DBA’s life interesting and in this blog post we have amazing story from Brian Kelley about the same subject. In this episode of the Notes from the Field series database expert Brian Kelley explains a how to find out what has changed in deleted database. Read the experience of Brian in his own words. Sometimes, one of the hardest questions to answer is, “What changed?” A similar question is, “Did anything change other than what we expected to change?” The First Place to Check – Schema Changes History Report: Pinal has recently written on the Schema Changes History report and its requirement for the Default Trace to be enabled. This is always the first place I look when I am trying to answer these questions. There are a couple of obvious limitations with the Schema Changes History report. First, while it reports what changed, when it changed, and who changed it, other than the base DDL operation (CREATE, ALTER, DELETE), it does not present what the changes actually were. This is not something covered by the default trace. Second, the default trace has a fixed size. When it hits that size, the changes begin to overwrite. As a result, if you wait too long, especially on a busy database server, you may find your changes rolled off. But the Database Has Been Deleted! Pinal cited another issue, and that’s the inability to run the Schema Changes History report if the database has been dropped. Thankfully, all is not lost. One thing to remember is that the Schema Changes History report is ultimately driven by the Default Trace. As you may have guess, it’s a trace, like any other database trace. And the Default Trace does write to disk. The trace files are written to the defined LOG directory for that SQL Server instance and have a prefix of log_: Therefore, you can read the trace files like any other. Tip: Copy the files to a working directory. Otherwise, you may occasionally receive a file in use error. With the Default Trace files, if you ask the question early enough, you can see the information for a deleted database just the same as any other database. Testing with a Deleted Database: Here’s a short script that will create a database, create a schema, create an object, and then drop the database. Without the database, you can’t do a standard Schema Changes History report. CREATE DATABASE DeleteMe; GO USE DeleteMe; GO CREATE SCHEMA Test AUTHORIZATION dbo; GO CREATE TABLE Test.Foo (FooID INT); GO USE MASTER; GO DROP DATABASE DeleteMe; GO This sets up the perfect situation where we can’t retrieve the information using the Schema Changes History report but where it’s still available. Finding the Information: I’ve sorted the columns so I can see the Event Subclass, the Start Time, the Database Name, the Object Name, and the Object Type at the front, but otherwise, I’m just looking at the trace files using SQL Profiler. As you can see, the information is definitely there: Therefore, even in the case of a dropped/deleted database, you can still determine who did what and when. You can even determine who dropped the database (loginame is captured). The key is to get the default trace files in a timely manner in order to extract the information. If you want to get started with performance tuning and database security with the help of experts, read more over at Fix Your SQL Server. Reference: Pinal Dave (http://blog.sqlauthority.com)Filed under: Notes from the Field, PostADay, SQL, SQL Authority, SQL Query, SQL Security, SQL Server, SQL Tips and Tricks, T SQL

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• Use your own domain email and tired of SPAM? SPAMfighter FTW

  - by Dave Campbell

  I wouldn't post this if I hadn't tried it... and I paid for it myself, so don't anybody be thinking I'm reviewing something someone sent me! Long ago and far away I got very tired of local ISPs and 2nd phone lines and took the plunge and got hooked up to cable... yeah I know the 2nd phone line concept may be hard for everyone to understand, but that's how it was in 'the old days'. To avoid having to change email addresses all the time, I decided to buy a domain name, get minimal hosting, and use that for all email into the house. That way if I changed providers, all the email addresses wouldn't have to change. Of course, about a dozen domains later, I have LOTS of pop email addresses and even an exchange address to my client's server... times have changed. What also has changed is the fact that we get SPAM... 'back in the day' when I was a beta tester for the first ISP in Phoenix, someone tried sending an ad to all of us, and what he got in return for his trouble was a bunch of core dumps that locked up his email... if you don't know what a core dump is, ask your grandfather. But in today's world, we're all much more civilized than that, and as with many things, the criminals seem to have much more rights than we do, so we get inundated with email offering all sorts of wild schemes that you'd have to be brain-dead to accept, but yet... if people weren't accepting them, they'd stop sending them. I keep hoping that survival of the smartest would weed out the mental midgets that respond and then the jumk email stop, but that hasn't happened yet anymore than finding high-quality hearing aids at the checkout line of Safeway because of all the dimwits playing music too loud inside their car... but that's another whole topic and I digress. So what's the solution for all the spam? And I mean *all*... on that old personal email address, I am now getting over 150 spam messages a day! Yes I know that's why God invented the delete key, but I took it on as a challenge, and it's a matter of principle... why should I switch email addresses, or convert from [email protected] to something else, or have all my email filtered through some service just because some A-Hole somewhere has a site up trying to phish Ma & Pa Kettle (ask your grandfather about that too) out of their retirement money? Well... I got an email from my cousin the other day while I was writing yet another email rule, and there was a banner on the bottom of his email that said he was protected by SPAMfighter. SPAMfighter huh.... so I took a look at their site, and found yet one more of the supposed tools to help us. But... I read that they're a Microsoft Gold Partner... and that doesn't come lightly... so I took a gamble and here's what I found: I installed it, and had to do a couple things: 1) SPAMfighter stuffed the SPAMfighter folder into my client's exchange address... I deleted it, made a new SPAMfighter folder where I wanted it to go, then in the SPAMfighter Clients settings for Outlook, I told it to put all spam there. 2) It didn't seem to be doing anything. There's a ribbon button that you can select "Block", and I did that, wondering if I was 'training' it, but it wasn't picking up duplicates 3) I sent email to support, and wrote a post on the forum (not to self: reply to that post). By the time the folks from the home office responded, it was the next day, and first up, SPAMfighter knocked down everything that came through when Outlook opend... two thumbs up! I disabled my 'garbage collection' rule from Outlook, and told Outlook not to use the junk folder thinking it was interfering. 4) Day 2 seemed to go about like Day 1... but I hung in there. 5) Day 3 is now a whole new day... I had left Outlook open and hadn't looked at the PC since sometime late yesterday afternoon, and when I looked this morning, *every bit* of spam was in the SPAMfighter folder!! I'm a new paying customer After watching SPAMfighter work this morning, I've purchased a 1-year license, and I now can sit and watch as emails come in and disappear from my inbox into the SPAMfighter folder. No more continual tweaking of the rules. I've got SPAMfighter set to 'Very Hard' filtering... personally I'd rather pull the few real emails out of the SPAMfighter folder than pull spam out of the real folders. Yes this is simply another way of using the delete key, but you know what? ... it feels good :) Here's a screenshot of the stats after just about 48 hours of being onboard: Note that all the ones blocked by me were during Day 1 and 2... I've blocked none today, and everything is blocked. Stay in the 'Light!

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• SQL SERVER – Backing Up and Recovering the Tail End of a Transaction Log – Notes from the Field #042

  - by Pinal Dave

  [Notes from Pinal]: The biggest challenge which people face is not taking backup, but the biggest challenge is to restore a backup successfully. I have seen so many different examples where users have failed to restore their database because they made some mistake while they take backup and were not aware of the same. Tail Log backup was such an issue in earlier version of SQL Server but in the latest version of SQL Server, Microsoft team has fixed the confusion with additional information on the backup and restore screen itself. Now they have additional information, there are a few more people confused as they have no clue about this. Previously they did not find this as a issue and now they are finding tail log as a new learning. Linchpin People are database coaches and wellness experts for a data driven world. In this 42nd episode of the Notes from the Fields series database expert Tim Radney (partner at Linchpin People) explains in a very simple words, Backing Up and Recovering the Tail End of a Transaction Log. Many times when restoring a database over an existing database SQL Server will warn you about needing to make a tail end of the log backup. This might be your reminder that you have to choose to overwrite the database or could be your reminder that you are about to write over and lose any transactions since the last transaction log backup. You might be asking yourself “What is the tail end of the transaction log”. The tail end of the transaction log is simply any committed transactions that have occurred since the last transaction log backup. This is a very crucial part of a recovery strategy if you are lucky enough to be able to capture this part of the log. Most organizations have chosen to accept some amount of data loss. You might be shaking your head at this statement however if your organization is taking transaction logs backup every 15 minutes, then your potential risk of data loss is up to 15 minutes. Depending on the extent of the issue causing you to have to perform a restore, you may or may not have access to the transaction log (LDF) to be able to back up those vital transactions. For example, if the storage array or disk that holds your transaction log file becomes corrupt or damaged then you wouldn’t be able to recover the tail end of the log. If you do have access to the physical log file then you can still back up the tail end of the log. In 2013 I presented a session at the PASS Summit called “The Ultimate Tail Log Backup and Restore” and have been invited back this year to present it again. During this session I demonstrate how you can back up the tail end of the log even after the data file becomes corrupt. In my demonstration I set my database offline and then delete the data file (MDF). The database can’t become more corrupt than that. I attempt to bring the database back online to change the state to RECOVERY PENDING and then backup the tail end of the log. I can do this by specifying WITH NO_TRUNCATE. Using NO_TRUNCATE is equivalent to specifying both COPY_ONLY and CONTINUE_AFTER_ERROR. It as its name says, does not try to truncate the log. This is a great demo however how could I achieve backing up the tail end of the log if the failure destroys my entire instance of SQL and all I had was the LDF file? During my demonstration I also demonstrate that I can attach the log file to a database on another instance and then back up the tail end of the log. If I am performing proper backups then my most recent full, differential and log files should be on a server other than the one that crashed. I am able to achieve this task by creating new database with the same name as the failed database. I then set the database offline, delete my data file and overwrite the log with my good log file. I attempt to bring the database back online and then backup the log with NO_TRUNCATE just like in the first example. I encourage each of you to view my blog post and watch the video demonstration on how to perform these tasks. I really hope that none of you ever have to perform this in production, however it is a really good idea to know how to do this just in case. It really isn’t a matter of “IF” you will have to perform a restore of a production system but more of a “WHEN”. Being able to recover the tail end of the log in these sever cases could be the difference of having to notify all your business customers of data loss or not. If you want me to take a look at your server and its settings, or if your server is facing any issue we can Fix Your SQL Server. Note: Tim has also written an excellent book on SQL Backup and Recovery, a must have for everyone. Reference: Pinal Dave (http://blog.sqlauthority.com)Filed under: Notes from the Field, PostADay, SQL, SQL Authority, SQL Performance, SQL Query, SQL Server, SQL Tips and Tricks, T SQL

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• pointer being freed was not allocated. Complex malloc history help

  - by Martin KS

  I've followed the guides helpfully linked here: http://stackoverflow.com/questions/295778/iphone-debugging-pointer-being-freed-was-not-allocated-errors but the malloc_history is really throwing me for a loop, can anyone shed any light on the following: ALLOC 0x185c600-0x18605ff [size=16384]: thread_a068a4e0 |start | main | UIApplicationMain | -[UIApplication _run] | CFRunLoopRunInMode | CFRunLoopRunSpecific | PurpleEventCallback | _UIApplicationHandleEvent | -[UIApplication sendEvent:] | -[UIApplication handleEvent:withNewEvent:] | -[UIApplication _reportAppLaunchFinished] | CA::Transaction::commit() | CA::Context::commit_transaction(CA::Transaction*) | CALayerCommitIfNeeded | CALayerCommitIfNeeded | CALayerCommitIfNeeded | CALayerCommitIfNeeded | CALayerCommitIfNeeded | CALayerCommitIfNeeded | CA::Context::commit_layer(_CALayer*, unsigned int, unsigned int, void*) | CA::Render::encode_set_object(CA::Render::Encoder*, unsigned long, unsigned int, CA::Render::Object*, unsigned int) | CA::Render::Layer::encode(CA::Render::Encoder*) const | CA::Render::Image::encode(CA::Render::Encoder*) const | CA::Render::Encoder::encode_data_async(void const*, unsigned long, void (*)(void const*, void*), void*) | CA::Render::Encoder::encode_bytes(void const*, unsigned long) | CA::Render::Encoder::grow(unsigned long) | realloc | malloc_zone_realloc ---- FREE 0x185c600-0x18605ff [size=16384]: thread_a068a4e0 |start | main | UIApplicationMain | -[UIApplication _run] | CFRunLoopRunInMode | CFRunLoopRunSpecific | PurpleEventCallback | _UIApplicationHandleEvent | -[UIApplication sendEvent:] | -[UIApplication handleEvent:withNewEvent:] | -[UIApplication _reportAppLaunchFinished] | CA::Transaction::commit() | CA::Context::commit_transaction(CA::Transaction*) | CALayerCommitIfNeeded | CALayerCommitIfNeeded | CALayerCommitIfNeeded | CALayerCommitIfNeeded | CALayerCommitIfNeeded | CALayerCommitIfNeeded | CA::Context::commit_layer(_CALayer*, unsigned int, unsigned int, void*) | CA::Render::encode_set_object(CA::Render::Encoder*, unsigned long, unsigned int, CA::Render::Object*, unsigned int) | CA::Render::Layer::encode(CA::Render::Encoder*) const | CA::Render::Image::encode(CA::Render::Encoder*) const | CA::Render::Encoder::encode_data_async(void const*, unsigned long, void (*)(void const*, void*), void*) | CA::Render::Encoder::encode_bytes(void const*, unsigned long) | CA::Render::Encoder::grow(unsigned long) | realloc | malloc_zone_realloc ALLOC 0x185e000-0x185e62f [size=1584]: thread_a068a4e0 |start | main | UIApplicationMain | GSEventRun | GSEventRunModal | CFRunLoopRunInMode | CFRunLoopRunSpecific | __NSFireDelayedPerform | -[UITableView _userSelectRowAtIndexPath:] | -[UITableView _selectRowAtIndexPath:animated:scrollPosition:notifyDelegate:] | -[PLAlbumView tableView:didSelectRowAtIndexPath:] | -[PLUIAlbumViewController albumView:selectedPhoto:] | PLNotifyImagePickerOfImageAvailability | -[UIImagePickerController _imagePickerDidCompleteWithInfo:] | -[GalleryViewController imagePickerController:didFinishPickingMediaWithInfo:] | UIImageJPEGRepresentation | CGImageDestinationFinalize | _CGImagePluginWriteJPEG | writeOne | _cg_jpeg_start_compress | _cg_jinit_compress_master | _cg_jinit_c_prep_controller | alloc_sarray | alloc_large | malloc | malloc_zone_malloc ---- FREE 0x185e000-0x185e62f [size=1584]: thread_a068a4e0 |start | main | UIApplicationMain | GSEventRun | GSEventRunModal | CFRunLoopRunInMode | CFRunLoopRunSpecific | __NSFireDelayedPerform | -[UITableView _userSelectRowAtIndexPath:] | -[UITableView _selectRowAtIndexPath:animated:scrollPosition:notifyDelegate:] | -[PL AlbumView tableView:didSelectRowAtIndexPath:] | -[PLUIAlbumViewController albumView:selectedPhoto:] | PLNotifyImagePickerOfImageAvailability | -[UIImagePickerController _imagePickerDidCompleteWithInfo:] | -[GalleryViewController imagePickerController:didFinishPickingMediaWithInfo:] | UIImageJPEGRepresentation | CGImageDestinationFinalize | _CGImagePluginWriteJPEG | writeOne | _cg_jpeg_abort | free_pool | free ALLOC 0x185c800-0x185ea1f [size=8736]: thread_a068a4e0 |start | main | UIApplicationMain | GSEventRun | GSEventRunModal | CFRunLoopRunInMode | CFRunLoopRunSpecific | __NSFireDelayedPerform | -[UITableView _userSelectRowAtIndexPath:] | -[UITableView _selectRowAtIndexPath:animated:scrollPosition:notifyDelegate:] | -[PLAlbumView tableView:didSelectRowAtIndexPath:] | -[PLUIAlbumViewController albumView:selectedPhoto:] | PLNotifyImagePickerOfImageAvailability | -[UIImagePickerController _imagePickerDidCompleteWithInfo:] | -[GalleryViewController imagePickerController:didFinishPickingMediaWithInfo:] | -[UIImage initWithData:] | _UIImageRefFromData | CGImageSourceCreateImageAtIndex | makeImagePlus | _CGImagePluginInitJPEG | initImageJPEG | calloc | malloc_zone_calloc

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• Blackberry stopwatch implementation

  - by Michaela

  I'm trying to write a blackberry app that is basically a stopwatch, and displays lap times. First, I'm not sure I'm implementing the stopwatch functionality in the most optimal way. I have a LabelField (_myLabel) that displays the 'clock' - starting at 00:00. Then you hit the start button and every second the _myLabel field gets updated with how many seconds have past since the last update (should only ever increment by 1, but sometimes there is a delay and it will skip a number). I just can't think of a different way to do it - and I am new to GUI development and threads so I guess that's why. EDIT: Here is what calls the stopwatch: _timer = new Timer(); _timer.schedule(new MyTimerTask(), 250, 250); And here is the TimerTask: class MyTimerTask extends TimerTask { long currentTime; long startTime = System.currentTimeMillis(); public void run() { synchronized (Application.getEventLock()) { currentTime = System.currentTimeMillis(); long diff = currentTime - startTime; long min = diff / 60000; long sec = (diff % 60000) / 1000; String minStr = new Long(min).toString(); String secStr = new Long(sec).toString(); if (min < 10) minStr = "0" + minStr; if (sec < 10) secStr = "0" + secStr; _myLabel.setText(minStr + ":" + secStr); timerDisplay.deleteAll(); timerDisplay.add(_timerLabel); } } } Anyway when you stop the stopwatch it updates a historical table of lap time data. When this list gets long, the timer starts to degrade. If you try to scroll, then it gets really bad. Is there a better way to implement my stopwatch?

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• 3n+1 problem at UVa

  - by ShahradR

  Hello, I am having trouble with the first question in the Programming Challenges book by Skiena and Revilla. I keep getting a "Wrong Answer" error message, and I don't know why. I've ran my code against the sample input, and I keep getting the right answer. Anyways, if anyone could help me, I would really appreciate it :) Here is the problem URL: http://uva.onlinejudge.org/index.php?option=com_onlinejudge&Itemid=8&category=29&page=show_problem&problem=36 And here is the code:` import java.util.Scanner; public class Main { static Scanner kb = new Scanner(System.in); public static void main(String[] args) { while (kb.hasNext()) { long[] numericalInput = {0, 0}; long i = kb.nextLong(); long j = kb.nextLong(); if (i > j) { numericalInput[0] = i; numericalInput[1] = j; } else { numericalInput[0] = j; numericalInput[1] = i; } long maxIterations = 0; for (long n = numericalInput[0]; n <= numericalInput[1]; n += 1) { if (maxIterations < returnIterations(n)) maxIterations = returnIterations(n); } System.out.println(i + " " + j + " " + maxIterations); } System.exit(0); } public static long returnIterations(long num) { long iterations = 0; while (num != 1) { if (num % 2 == 0) num = num / 2; else num = 3 * num + 1; iterations += 1; } iterations += 1; return iterations; } } ` EDIT: I think the problem is with the output. I tried to make it accept all the input first and then display all the answers at once, but I didn't know the terminating condition. I resorted to this method, but I'm not sure that's what the judge wants...

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• Why do I get Detached Entity exception when upgrading Spring Boot 1.1.4 to 1.1.5

  - by mmeany

  On updating Spring Boot from 1.1.4 to 1.1.5 a simple web application started generating detached entity exceptions. Specifically, a post authentication inteceptor that bumped number of visits was causing the problem. A quick check of loaded dependencies showed that Spring Data has been updated from 1.6.1 to 1.6.2 and a further check of the change log shows a couple of issues relating to optimistic locking, version fields and JPA issues that have been fixed. Well I am using a version field and it starts out as Null following recommendation to not set in the specification. I have produced a very simple test scenario where I get detached entity exceptions if the version field starts as null or zero. If I create an entity with version 1 however then I do not get these exceptions. Is this expected behaviour or is there still something amiss? Below is the test scenario I have for this condition. In the scenario the service layer that has been annotated @Transactional. Each test case makes multiple calls to the service layer - the tests are working with detached entities as this is the scenario I am working with in the full blown application. The test case comprises four tests: Test 1 - versionNullCausesAnExceptionOnUpdate() In this test the version field in the detached object is Null. This is how I would usually create the object prior to passing to the service. This test fails with a Detached Entity exception. I would have expected this test to pass. If there is a flaw in the test then the rest of the scenario is probably moot. Test 2 - versionZeroCausesExceptionOnUpdate() In this test I have set the version to value Long(0L). This is an edge case test and included because I found reference to Zero values being used for version field in the Spring Data change log. This test fails with a Detached Entity exception. Of interest simply because the following two tests pass leaving this as an anomaly. Test 3 - versionOneDoesNotCausesExceptionOnUpdate() In this test the version field is set to value Long(1L). Not something I would usually do, but considering the notes in the Spring Data change log I decided to give it a go. This test passes. Would not usually set the version field, but this looks like a work-around until I figure out why the first test is failing. Test 4 - versionOneDoesNotCausesExceptionWithMultipleUpdates() Encouraged by the result of test 3 I pushed the scenario a step further and perform multiple updates on the entity that started life with a version of Long(1L). This test passes. Reinforcement that this may be a useable work-around. The entity: package com.mvmlabs.domain; import javax.persistence.Column; import javax.persistence.Entity; import javax.persistence.GeneratedValue; import javax.persistence.GenerationType; import javax.persistence.Id; import javax.persistence.Table; import javax.persistence.Version; @Entity @Table(name="user_details") public class User { @Id @GeneratedValue(strategy=GenerationType.AUTO) private Long id; @Version private Long version; @Column(nullable = false, unique = true) private String username; @Column(nullable = false) private Integer numberOfVisits; public Long getId() { return id; } public void setId(Long id) { this.id = id; } public Long getVersion() { return version; } public void setVersion(Long version) { this.version = version; } public Integer getNumberOfVisits() { return numberOfVisits == null ? 0 : numberOfVisits; } public void setNumberOfVisits(Integer numberOfVisits) { this.numberOfVisits = numberOfVisits; } public String getUsername() { return username; } public void setUsername(String username) { this.username = username; } } The repository: package com.mvmlabs.dao; import org.springframework.data.repository.CrudRepository; import com.mvmlabs.domain.User; public interface UserDao extends CrudRepository<User, Long>{ } The service interface: package com.mvmlabs.service; import com.mvmlabs.domain.User; public interface UserService { User save(User user); User loadUser(Long id); User registerVisit(User user); } The service implementation: package com.mvmlabs.service; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.stereotype.Service; import org.springframework.transaction.annotation.Propagation; import org.springframework.transaction.annotation.Transactional; import org.springframework.transaction.support.TransactionSynchronizationManager; import com.mvmlabs.dao.UserDao; import com.mvmlabs.domain.User; @Service @Transactional(propagation=Propagation.REQUIRED, readOnly=false) public class UserServiceJpaImpl implements UserService { @Autowired private UserDao userDao; @Transactional(readOnly=true) @Override public User loadUser(Long id) { return userDao.findOne(id); } @Override public User registerVisit(User user) { user.setNumberOfVisits(user.getNumberOfVisits() + 1); return userDao.save(user); } @Override public User save(User user) { return userDao.save(user); } } The application class: package com.mvmlabs; import org.springframework.boot.SpringApplication; import org.springframework.boot.autoconfigure.EnableAutoConfiguration; import org.springframework.context.annotation.ComponentScan; import org.springframework.context.annotation.Configuration; @Configuration @ComponentScan @EnableAutoConfiguration public class Application { public static void main(String[] args) { SpringApplication.run(Application.class, args); } } The POM: <?xml version="1.0" encoding="UTF-8"?> <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"> <modelVersion>4.0.0</modelVersion> <groupId>com.mvmlabs</groupId> <artifactId>jpa-issue</artifactId> <version>0.0.1-SNAPSHOT</version> <packaging>jar</packaging> <name>spring-boot-jpa-issue</name> <description>JPA Issue between spring boot 1.1.4 and 1.1.5</description> <parent> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-parent</artifactId> <version>1.1.5.RELEASE</version> <relativePath /> <!-- lookup parent from repository --> </parent> <dependencies> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-data-jpa</artifactId> </dependency> <dependency> <groupId>org.hsqldb</groupId> <artifactId>hsqldb</artifactId> <scope>runtime</scope> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-test</artifactId> <scope>test</scope> </dependency> </dependencies> <properties> <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding> <start-class>com.mvmlabs.Application</start-class> <java.version>1.7</java.version> </properties> <build> <plugins> <plugin> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-maven-plugin</artifactId> </plugin> </plugins> </build> </project> The application properties: spring.jpa.hibernate.ddl-auto: create spring.jpa.hibernate.naming_strategy: org.hibernate.cfg.ImprovedNamingStrategy spring.jpa.database: HSQL spring.jpa.show-sql: true spring.datasource.url=jdbc:hsqldb:file:./target/testdb spring.datasource.username=sa spring.datasource.password= spring.datasource.driverClassName=org.hsqldb.jdbcDriver The test case: package com.mvmlabs; import org.junit.Assert; import org.junit.Test; import org.junit.runner.RunWith; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.boot.test.SpringApplicationConfiguration; import org.springframework.test.context.junit4.SpringJUnit4ClassRunner; import com.mvmlabs.domain.User; import com.mvmlabs.service.UserService; @RunWith(SpringJUnit4ClassRunner.class) @SpringApplicationConfiguration(classes = Application.class) public class ApplicationTests { @Autowired UserService userService; @Test public void versionNullCausesAnExceptionOnUpdate() throws Exception { User user = new User(); user.setUsername("Version Null"); user.setNumberOfVisits(0); user.setVersion(null); user = userService.save(user); user = userService.registerVisit(user); Assert.assertEquals(new Integer(1), user.getNumberOfVisits()); Assert.assertEquals(new Long(1L), user.getVersion()); } @Test public void versionZeroCausesExceptionOnUpdate() throws Exception { User user = new User(); user.setUsername("Version Zero"); user.setNumberOfVisits(0); user.setVersion(0L); user = userService.save(user); user = userService.registerVisit(user); Assert.assertEquals(new Integer(1), user.getNumberOfVisits()); Assert.assertEquals(new Long(1L), user.getVersion()); } @Test public void versionOneDoesNotCausesExceptionOnUpdate() throws Exception { User user = new User(); user.setUsername("Version One"); user.setNumberOfVisits(0); user.setVersion(1L); user = userService.save(user); user = userService.registerVisit(user); Assert.assertEquals(new Integer(1), user.getNumberOfVisits()); Assert.assertEquals(new Long(2L), user.getVersion()); } @Test public void versionOneDoesNotCausesExceptionWithMultipleUpdates() throws Exception { User user = new User(); user.setUsername("Version One Multiple"); user.setNumberOfVisits(0); user.setVersion(1L); user = userService.save(user); user = userService.registerVisit(user); user = userService.registerVisit(user); user = userService.registerVisit(user); Assert.assertEquals(new Integer(3), user.getNumberOfVisits()); Assert.assertEquals(new Long(4L), user.getVersion()); } } The first two tests fail with detached entity exception. The last two tests pass as expected. Now change Spring Boot version to 1.1.4 and rerun, all tests pass. Are my expectations wrong? Edit: This code saved to GitHub at https://github.com/mmeany/spring-boot-detached-entity-issue

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• Can you tell me why this generates time limit exceeded in spoj(Prime Number Generator)

  - by magiix

  #include<iostream> #include<string.h> #include<math.h> using namespace std; bool prime[1000000500]; void generate(long long end) { memset(prime,true,sizeof(prime)); prime[0]=false; prime[1]=false; for(long long i=0;i<=sqrt(end);i++) { if(prime[i]==true) { for(long long y=i*i;y<=end;y+=i) { prime[y]=false; } } } } int main() { int n; long long b,e; scanf("%d",&n); while(n--) { cin>>b>>e; generate(e); for(int i=b;i<e;i++) { if(prime[i]) printf("%d\n",i); } } return 0; } That's my code for spoj prime generator. Altought it generates the same output as another accepted code ..

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• C#, finding the largest prime factor of a number

  - by Juan

  Hello! I am new at programming and I am practicing my C# programming skills. My application is meant to find the largest prime factor of a number entered by the user. But my application is not returning the right answer and I dont really know where the problem is. Can you please help me? using System; using System.Collections.Generic; using System.Linq; using System.Text; namespace ConsoleApplication1 { class Program { static void Main(string[] args) { Console.WriteLine("Calcular máximo factor primo de n. De 60 es 5."); Console.Write("Escriba un numero: "); long num = Convert.ToInt64(Console.ReadLine()); long mfp = maxfactor(num); Console.WriteLine("El maximo factor primo es: " + num); Console.Read(); } static private long maxfactor (long n) { long m=1 ; bool en= false; for (long k = n / 2; !en && k > 1; k--) { if (n % k == 0 && primo(k)) { m = k; en = true; } } return m; } static private bool primo(long x) { bool sp = true; for (long i = 2; i <= x / 2; i++) { if (x % i == 0) sp = false; } return sp; } } }

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• Insert MANY key value pairs fast into berkeley db with hash access

  - by Kungi

  Hi, i'm trying to build a hash with berkeley db, which shall contain many tuples (approx 18GB of key value pairs), but in all my tests the performance of the insert operations degrades drastically over time. I've written this script to test the performance: #include<iostream> #include<db_cxx.h> #include<ctime> #define MILLION 1000000 int main () { long long a = 0; long long b = 0; int passes = 0; int i = 0; u_int32_t flags = DB_CREATE; Db* dbp = new Db(NULL,0); dbp->set_cachesize( 0, 1024 * 1024 * 1024, 1 ); int ret = dbp->open( NULL, "test.db", NULL, DB_HASH, flags, 0); time_t time1 = time(NULL); while ( passes < 100 ) { while( i < MILLION ) { Dbt key( &a, sizeof(long long) ); Dbt data( &b, sizeof(long long) ); dbp->put( NULL, &key, &data, 0); a++; b++; i++; } DbEnv* dbep = dbp->get_env(); int tmp; dbep->memp_trickle( 50, &tmp ); i=0; passes++; std::cout << "Inserted one million --> pass: " << passes << " took: " << time(NULL) - time1 << "sec" << std::endl; time1 = time(NULL); } } Perhaps you can tell me why after some time the "put" operation takes increasingly longer and maybe how to fix this. Thanks for your help, Andreas

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• Simplest way to automatically alter "const" value in Java during compile time

  - by Michael Mao

  Hi all: This is a question corresponds to my uni assignment so I am very sorry to say I cannot adopt any one of the following best practices in a short time -- you know -- assignment is due tomorrow :( link to Best way to alter const in Java on StackOverflow Basically the only task (I hope so) left for me is the performance tuning. I've got a bunch of predefined "const" values in my single-class agent source code like this: //static final values private static final long FT_THRESHOLD = 400; private static final long FT_THRESHOLD_MARGIN = 50; private static final long FT_SMOOTH_PRICE_IDICATOR = 20; private static final long FT_BUY_PRICE_MODIFIER = 0; private static final long FT_LAST_ROUNDS_STARTTIME = 90; private static final long FT_AMOUNT_ADJUST_MODIFIER = 5; private static final long FT_HISTORY_PIRCES_LENGTH = 10; private static final long FT_TRACK_DURATION = 5; private static final int MAX_BED_BID_NUM_PER_AUC = 12; I can definitely alter the values manually and then compile the code to give it another go around. But the execution time for a thorough "statistic analysis" usually requires over 2000 times of execution, which will typically lasts more than half an hour on my own laptop... So I hope there is a way to alter values using other ways than dig into the source code to change the "const" values there, so I can automatically distributed compiled code to other people's PC and let them run the statistic analysis instead. One other reason for a automatically value adjustment is that I can try using my own agent to defeat itself by choosing different "const" values. Although my values are derived from previous history and statistical results, they are far from the most optimized values. I hope there is a easy way so I can quickly adopt that so to have a good sleep tonight while the computer does everything for me... :) Any hints on this sort of stuff? Any suggestion is welcomed and much appreciated.

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• Getting a handle on GIS math, where do I start?

  - by Joshua

  I am in charge of a program that is used to create a set of nodes and paths for consumption by an autonomous ground vehicle. The program keeps track of the locations of all items in its map by indicating the item's position as being x meters north and y meters east of an origin point of 0,0. In the real world, the vehicle knows the location of the origin's lat and long, as it is determined by a dgps system and is accurate down to a couple centimeters. My program is ignorant of any lat long coordinates. It is one of my goals to modify the program to keep track of lat long coords of items in addition to an origin point and items' x,y position in relation to that origin. At first blush, it seems that I am going to modify the program to allow the lat long coords of the origin to be passed in, and after that I desire that the program will automatically calculate the lat long of every item currently in a map. From what I've researched so far, I believe that I will need to figure out the math behind converting to lat long coords from a UTM like projection where I specify the origin points and meridians etc as opposed to whatever is defined already for UTM. I've come to ask of you GIS programmers, am I on the right track? It seems to me like there is so much to wrap ones head around, and I'm not sure if the answer isn't something as simple as, "oh yea theres a conversion from meters to lat long, here" Currently, due to the nature of DGPS, the system really doesn't need to care about locations more than oh, what... 40 km? radius away from the origin. Given this, and the fact that I need to make sure that the error on my coordinates is not greater than .5 meters, do I need anything more complex than a simple lat/long to meters conversion constant? I'm knee deep in materials here. I could use some pointers about what concepts to research. Thanks much!

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• Why is calling close() after fopen() not closing?

  - by Richard Morgan

  I ran across the following code in one of our in-house dlls and I am trying to understand the behavior it was showing: long GetFD(long* fd, const char* fileName, const char* mode) { string fileMode; if (strlen(mode) == 0 || tolower(mode[0]) == 'w' || tolower(mode[0]) == 'o') fileMode = string("w"); else if (tolower(mode[0]) == 'a') fileMode = string("a"); else if (tolower(mode[0]) == 'r') fileMode = string("r"); else return -1; FILE* ofp; ofp = fopen(fileName, fileMode.c_str()); if (! ofp) return -1; *fd = (long)_fileno(ofp); if (*fd < 0) return -1; return 0; } long CloseFD(long fd) { close((int)fd); return 0; } After repeated calling of GetFD with the appropriate CloseFD, the whole dll would no longer be able to do any file IO. I wrote a tester program and found that I could GetFD 509 times, but the 510th time would error. Using Process Explorer, the number of Handles did not increase. So it seems that the dll is reaching the limit for the number of open files; setting _setmaxstdio(2048) does increase the amount of times we can call GetFD. Obviously, the close() is working quite right. After a bit of searching, I replaced the fopen() call with: long GetFD(long* fd, const char* fileName, const char* mode) { *fd = (long)open(fileName, 2); if (*fd < 0) return -1; return 0; } Now, repeatedly calling GetFD/CloseFD works. What is going on here?

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• How long will a "safely stored" Solid-State-Drive (SSD) keep its data? (e.g. bank safety-deposit box)

  - by user31575

  Here's my usecase: once-and-only-once copy off photos/videos to an internal SATA Solid State Drive (SSD) put this drive in a well-ventilated, air-conditioned bank "safety deposit box" for safe keeping The question: How long can I safely store a solid-state-drive in such an environment? i.e. 0% bitrot, 100% success when "plugged in" Are some SSD drives more reliable than other for this usecase? (e.g. smaller size vs larger size, SLC vs MLC, different brands, etc) More fodder: I have read that solid state memory cards (e..g compactflash, or sd cards) have much longer durability than other media (DVD's, CD's, hard drives) for this usecase (guaranteed against bitrot/other dysfunction on the order of ~ a decades vs a year ). I don't know if this applies to "SSD hard drives". Copying to one 500Gb ssd vs 8 64gb flash drives is easier SSD SATA hard drives have no moving parts, but they have more "visible electronics" than a compact flash card. I don't know if this "visible electronics" can fail, i.e. in contr I know many will point to carbonite, other cloud backup stuff, but I like the simplicity of having physical copies and wanted to understand the risks/implications thanks,

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• Conversion from C code to CudaC code I get unpredictable results

  - by Abhi

  include include include include define pi 3.14159265359 lo*lo*p-2*mu,freq=2.25*1e6,wavelength=(long double)lo/freq,dh=(long double)wavelength/ 30.0,dt=(long double)dh/(lo*1.5); (1000*dh)); (p*dh),lambdaplus2mudtbydh=(lambda+2*mu)*dt/dh,lambdadtbydh=lambda*dt/dh,dtmubydh=dt*mu/ dh; double**U,long double**V){ for(int k=0,l=0;k<=yno-1 && l<=yno;k++,l++){ U[i+1][l]+=dtbyrhodh*(X[i+1][l+1]-X[i+1][l]+Z[i+1][l]- Z[i][l]); [k+1]-Y[j][k+1]); } double**U,long double**V){ for(int k=0,l=0;k<=yno-1 && l<=yno;k++,l++){ U[i+1][k])+lambdadtbydh*(V[i+1][k+1]-V[i][k+1]); V[i][k+1])+lambdadtbydh*(U[i+1][k+1]-U[i+1][k]); U[j][l]); int main(){ clock_t start,end; long double time_taken; start=clock(); long double **X,**Y,**U,**V,**Z;int n=1; X=Make2DDoubleArray(xno+2,yno+2); Y=Make2DDoubleArray(xno+2,yno+2); Z=Make2DDoubleArray(xno+1,yno+1); U=Make2DDoubleArray(xno+2,yno+2); V=Make2DDoubleArray(xno+2,yno+2); for (n=1;n<=timesteps;n++){ } end=clock(); time_taken=(long double)(end-start)/CLOCKS_PER_SEC; printf("Time elapsed is %Lf\nGRID Size:%Lf*%Lf\nTime Steps Taken:%d\n",time_taken,(xno),floor(yno),n); return 0; }

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• Implementing a bitfield using java enums

  - by soappatrol

  Hello, I maintain a large document archive and I often use bit fields to record the status of my documents during processing or when validating them. My legacy code simply uses static int constants such as: static int DOCUMENT_STATUS_NO_STATE = 0 static int DOCUMENT_STATUS_OK = 1 static int DOCUMENT_STATUS_NO_TIF_FILE = 2 static int DOCUMENT_STATUS_NO_PDF_FILE = 4 This makes it pretty easy to indicate the state a document is in, by setting the appropriate flags. For example: status = DOCUMENT_STATUS_NO_TIF_FILE | DOCUMENT_STATUS_NO_PDF_FILE; Since the approach of using static constants is bad practice and because I would like to improve the code, I was looking to use Enums to achieve the same. There are a few requirements, one of them being the need to save the status into a database as a numeric type. So there is a need to transform the enumeration constants to a numeric value. Below is my first approach and I wonder if this is the correct way to go about this? class DocumentStatus{ public enum StatusFlag { DOCUMENT_STATUS_NOT_DEFINED(1<<0), DOCUMENT_STATUS_OK(1<<1), DOCUMENT_STATUS_MISSING_TID_DIR(1<<2), DOCUMENT_STATUS_MISSING_TIF_FILE(1<<3), DOCUMENT_STATUS_MISSING_PDF_FILE(1<<4), DOCUMENT_STATUS_MISSING_OCR_FILE(1<<5), DOCUMENT_STATUS_PAGE_COUNT_TIF(1<<6), DOCUMENT_STATUS_PAGE_COUNT_PDF(1<<7), DOCUMENT_STATUS_UNAVAILABLE(1<<8), private final long statusFlagValue; StatusFlag(long statusFlagValue) { this.statusFlagValue = statusFlagValue } public long getStatusFlagValue(){ return statusFlagValue } } /** * Translates a numeric status code into a Set of StatusFlag enums * @param numeric statusValue * @return EnumSet representing a documents status */ public EnumSet<StatusFlag> getStatusFlags(long statusValue) { EnumSet statusFlags = EnumSet.noneOf(StatusFlag.class) StatusFlag.each { statusFlag -> long flagValue = statusFlag.statusFlagValue if ( (flagValue&statusValue ) == flagValue ) { statusFlags.add(statusFlag) } } return statusFlags } /** * Translates a set of StatusFlag enums into a numeric status code * @param Set if statusFlags * @return numeric representation of the document status */ public long getStatusValue(Set<StatusFlag> flags) { long value=0 flags.each { statusFlag -> value|=statusFlag.getStatusFlagValue() } return value } public static void main(String[] args) { DocumentStatus ds = new DocumentStatus(); Set statusFlags = EnumSet.of( StatusFlag.DOCUMENT_STATUS_OK, StatusFlag.DOCUMENT_STATUS_UNAVAILABLE) assert ds.getStatusValue( statusFlags )==258 // 0000.0001|0000.0010 long numericStatusCode = 56 statusFlags = ds.getStatusFlags(numericStatusCode) assert !statusFlags.contains(StatusFlag.DOCUMENT_STATUS_OK) assert statusFlags.contains(StatusFlag.DOCUMENT_STATUS_MISSING_TIF_FILE) assert statusFlags.contains(StatusFlag.DOCUMENT_STATUS_MISSING_PDF_FILE) assert statusFlags.contains(StatusFlag.DOCUMENT_STATUS_MISSING_OCR_FILE) } }

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• When to pass pointers in functions?

  - by yCalleecharan

  scenario 1 Say my function declaration looks like this: void f(long double k[], long double y[], long double A, long double B) { k[0] = A * B; k[1] = A * y[1]; return; } where k and y are arrays, and A and B are numerical values that don't change. My calling function is f(k1, ya, A, B); Now, the function f is only modifying the array "k" or actually elements in the array k1 in the calling function. We see that A and B are numerical values that don't change values when f is called. scenario 2 If I use pointers on A and B, I have, the function declaration as void f(long double k[], long double y[], long double *A, long double *B) { k[0] = *A * *B; k[1] = *A * y[1]; return; } and the calling function is modified as f(k1, ya, &A, &B); I have two questions: Both scenarios 1 and 2 will work. In my opinion, scenario 1 is good when values A and B are not being modified by the function f while scenario 2 (passing A and B as pointers) is applicable when the function f is actually changing values of A and B due to some other operation like *A = *B + 2 in the function declaration. Am I thinking right? Both scenarios are can used equally only when A and B are not being changed in f. Am I right? Thanks a lot...

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• SQL SERVER – Weekly Series – Memory Lane – #051

  - by Pinal Dave

  Here is the list of selected articles of SQLAuthority.com across all these years. Instead of just listing all the articles I have selected a few of my most favorite articles and have listed them here with additional notes below it. Let me know which one of the following is your favorite article from memory lane. 2007 Explanation and Understanding NOT NULL Constraint NOT NULL is integrity CONSTRAINT. It does not allow creating of the row where column contains NULL value. Most discussed questions about NULL is what is NULL? I will not go in depth analysis it. Simply put NULL is unknown or missing data. When NULL is present in database columns, it can affect the integrity of the database. I really do not prefer NULL in the database unless they are absolutely necessary. Three T-SQL Script to Create Primary Keys on Table I have always enjoyed writing about three topics Constraint and Keys, Backup and Restore and Datetime Functions. Primary Keys constraints prevent duplicate values for columns and provides a unique identifier to each column, as well it creates clustered index on the columns. 2008 Get Numeric Value From Alpha Numeric String – UDF for Get Numeric Numbers Only SQL is great with String operations. Many times, I use T-SQL to do my string operation. Let us see User Defined Function, which I wrote a few days ago, which will return only Numeric values from Alpha Numeric values. Introduction and Example of UNION and UNION ALL It is very much interesting when I get requests from blog reader to re-write my previous articles. I have received few requests to rewrite my article SQL SERVER – Union vs. Union All – Which is better for performance? with examples. I request you to read my previous article first to understand what is the concept and read this article to understand the same concept with an example. Downgrade Database for Previous Version The main questions is how they can downgrade the from SQL Server 2005 to SQL Server 2000? The answer is : Not Possible. Get Common Records From Two Tables Without Using Join Following is my scenario, Suppose Table 1 and Table 2 has same column e.g. Column1 Following is the query, 1. Select column1,column2 From Table1 2. Select column1 From Table2 I want to find common records from these tables, but I don’t want to use the Join clause because for that I need to specify the column name for Join condition. Will you help me to get common records without using Join condition? I am using SQL Server 2005. Retrieve – Select Only Date Part From DateTime – Best Practice – Part 2 A year ago I wrote a post about SQL SERVER – Retrieve – Select Only Date Part From DateTime – Best Practice where I have discussed two different methods of getting the date part from datetime. Introduction to CLR – Simple Example of CLR Stored Procedure CLR is an abbreviation of Common Language Runtime. In SQL Server 2005 and later version of it database objects can be created which are created in CLR. Stored Procedures, Functions, Triggers can be coded in CLR. CLR is faster than T-SQL in many cases. CLR is mainly used to accomplish tasks which are not possible by T-SQL or can use lots of resources. The CLR can be usually implemented where there is an intense string operation, thread management or iteration methods which can be complicated for T-SQL. Implementing CLR provides more security to the Extended Stored Procedure. 2009 Comic Slow Query – SQL Joke Before Presentation After Presentation Enable Automatic Statistic Update on Database In one of the recent projects, I found out that despite putting good indexes and optimizing the query, I could not achieve an optimized performance and I still received an unoptimized response from the SQL Server. On examination, I figured out that the culprit was statistics. The database that I was trying to optimize had auto update of the statistics was disabled. Recently Executed T-SQL Query Please refer to blog post  query to recently executed T-SQL query on database. Change Collation of Database Column – T-SQL Script – Consolidating Collations – Extention Script At some time in your DBA career, you may find yourself in a position when you sit back and realize that your database collations have somehow run amuck, or are faced with the ever annoying CANNOT RESOLVE COLLATION message when trying to join data of varying collation settings. 2010 Visiting Alma Mater – Delivering Session on Database Performance and Career – Nirma Institute of Technology Everyone always dreams of visiting their school and college, where they have studied once. It is a great feeling to see the college once again – where you have spent the wonderful golden years of your time. College time is filled with studies, education, emotions and several plans to build a future. I consider myself fortunate as I got the opportunity to study at some of the best places in the world. Change Column DataTypes There are times when I feel like writing that I am a day older in SQL Server. In fact, there are many who are looking for a solution that is simple enough. Have you ever searched online for something very simple. I often do and enjoy doing things which are straight forward and easy to change. 2011 Three DMVs – sys.dm_server_memory_dumps – sys.dm_server_services – sys.dm_server_registry In this blog post we will see three new DMVs which are introduced in Denali. The DMVs are very simple and there is not much to describe them. So here is the simple game. I will be asking a question back to you after seeing the result of the each of the DMV and you help me to complete this blog post. A Simple Quiz – T-SQL Brain Trick If you have some time, I strongly suggest you try this quiz out as it is for sure twists your brain. 2012 List All The Column With Specific Data Types in Database 5 years ago I wrote script SQL SERVER – 2005 – List All The Column With Specific Data Types, when I read it again, it is very much relevant and I liked it. This is one of the script which every developer would like to keep it handy. I have upgraded the script bit more. I have included few additional information which I believe I should have added from the beginning. It is difficult to visualize the final script when we are writing it first time. Find First Non-Numeric Character from String The function PATINDEX exists for quite a long time in SQL Server but I hardly see it being used. Well, at least I use it and I am comfortable using it. Here is a simple script which I use when I have to identify first non-numeric character. Finding Different ColumnName From Almost Identitical Tables Well here is the interesting example of how we can use sys.column catalogue views and get the details of the newly added column. I have previously written about EXCEPT over here which is very similar to MINUS of Oracle. Storing Data and Files in Cloud – Dropbox – Personal Technology Tip I thought long and hard about doing a Personal Technology Tips series for this blog.  I have so many tips I’d like to share.  I am on my computer almost all day, every day, so I have a treasure trove of interesting tidbits I like to share if given the chance.  The only thing holding me back – which tip to share first?  The first tip obviously has the weight of seeming like the most important.  But this would mean choosing amongst my favorite tricks and shortcuts.  This is a hard task. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: Memory Lane, PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology

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