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  • SQL SERVER – Concurrancy Problems and their Relationship with Isolation Level

    - by pinaldave
    Concurrency is simply put capability of the machine to support two or more transactions working with the same data at the same time. This usually comes up with data is being modified, as during the retrieval of the data this is not the issue. Most of the concurrency problems can be avoided by SQL Locks. There are four types of concurrency problems visible in the normal programming. 1)      Lost Update – This problem occurs when there are two transactions involved and both are unaware of each other. The transaction which occurs later overwrites the transactions created by the earlier update. 2)      Dirty Reads – This problem occurs when a transactions selects data that isn’t committed by another transaction leading to read the data which may not exists when transactions are over. Example: Transaction 1 changes the row. Transaction 2 changes the row. Transaction 1 rolls back the changes. Transaction 2 has selected the row which does not exist. 3)      Nonrepeatable Reads – This problem occurs when two SELECT statements of the same data results in different values because another transactions has updated the data between the two SELECT statements. Example: Transaction 1 selects a row, which is later on updated by Transaction 2. When Transaction A later on selects the row it gets different value. 4)      Phantom Reads – This problem occurs when UPDATE/DELETE is happening on one set of data and INSERT/UPDATE is happening on the same set of data leading inconsistent data in earlier transaction when both the transactions are over. Example: Transaction 1 is deleting 10 rows which are marked as deleting rows, during the same time Transaction 2 inserts row marked as deleted. When Transaction 1 is done deleting rows, there will be still rows marked to be deleted. When two or more transactions are updating the data, concurrency is the biggest issue. I commonly see people toying around with isolation level or locking hints (e.g. NOLOCK) etc, which can very well compromise your data integrity leading to much larger issue in future. Here is the quick mapping of the isolation level with concurrency problems: Isolation Dirty Reads Lost Update Nonrepeatable Reads Phantom Reads Read Uncommitted Yes Yes Yes Yes Read Committed No Yes Yes Yes Repeatable Read No No No Yes Snapshot No No No No Serializable No No No No I hope this 400 word small article gives some quick understanding on concurrency issues and their relation to isolation level. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology

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  • SQL SERVER – Introduction to Function SIGN

    - by pinaldave
    Yesterday I received an email from a friend asking how do SIGN function works. Well SIGN Function is very fundamental function. It will return the value 1, -1 or 0. If your value is negative it will return you negative -1 and if it is positive it will return you positive +1. Let us start with a simple small example. DECLARE @IntVal1 INT, @IntVal2 INT,@IntVal3 INT DECLARE @NumVal1 DECIMAL(4,2), @NumVal2 DECIMAL(4,2),@NumVal3 DECIMAL(4,2) SET @IntVal1 = 9; SET @IntVal2 = -9; SET @IntVal3 = 0; SET @NumVal1 = 9.0; SET @NumVal2 = -9.0; SET @NumVal3 = 0.0; SELECT SIGN(@IntVal1) IntVal1,SIGN(@IntVal2) IntVal2,SIGN(@IntVal3) IntVal3 SELECT SIGN(@NumVal1) NumVal1,SIGN(@NumVal2) NumVal2,SIGN(@NumVal2) NumVal3   The above function will give us following result set. You will notice that when there is positive value the function gives positive values and if the values are negative it will return you negative values. Also you will notice that if the data type is  INT the return value is INT and when the value passed to the function is Numeric the result also matches it. Not every datatype is compatible with this function.  Here is the quick look up of the return types. bigint -> bigint int/smallint/tinyint -> int money/smallmoney -> money numeric/decimal -> numeric/decimal everybody else -> float What will be the best example of the usage of this function that you will not have to use the CASE Statement. Here is example of CASE Statement usage and the same replaced with SIGN function. USE tempdb GO CREATE TABLE TestTable (Date1 SMALLDATETIME, Date2 SMALLDATETIME) INSERT INTO TestTable (Date1, Date2) SELECT '2012-06-22 16:15', '2012-06-20 16:15' UNION ALL SELECT '2012-06-24 16:15', '2012-06-22 16:15' UNION ALL SELECT '2012-06-22 16:15', '2012-06-22 16:15' GO -- Using Case Statement SELECT CASE WHEN DATEDIFF(d,Date1,Date2) > 0 THEN 1 WHEN DATEDIFF(d,Date1,Date2) < 0 THEN -1 ELSE 0 END AS Col FROM TestTable GO -- Using SIGN Function SELECT SIGN(DATEDIFF(d,Date1,Date2)) AS Col FROM TestTable GO DROP TABLE TestTable GO This was interesting blog post for me to write. Let me know your opinion. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: PostADay, SQL, SQL Authority, SQL Function, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology

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  • SQL SERVER – Script to Update a Specific Column in Entire Database

    - by Pinal Dave
    Last week, I have received a very interesting question and I find in email and I really liked the question as I had to play around with SQL Script for a while to come up with the answer he was looking for. Please read the question and I believe that all of us face this kind of situation. “Pinal, In our database we have recently introduced ModifiedDate column in all of the tables. Now onwards any update happens in the row, we are updating current date and time to that field. Now here is the issue, when we added that field we did not update it with a default value because we were not sure when we will go live with the system so we let it be NULL. Now modification to the application went live yesterday and we are now updating this field. Here is where I need your help. We need to update all the tables in our database where we have column created ModifiedDate and now want to update with current datetime. As our system is already live since yesterday there are several thousands of the rows which are already updated with real world value so we do not want to update those values. Essentially, in our entire database where ever there is a ModifiedDate column and if it is NULL we want to update that with current date time?  Do you have a script for it?” Honestly I did not have such a script. This is very specific required but I was able to come up with two different methods how he can use this method. Method 1 : Using INFORMATION_SCHEMA SELECT 'UPDATE ' + T.TABLE_SCHEMA + '.' + T.TABLE_NAME + ' SET ModifiedDate = GETDATE() WHERE ModifiedDate IS NULL;' FROM INFORMATION_SCHEMA.TABLES T INNER JOIN INFORMATION_SCHEMA.COLUMNS C ON T.TABLE_NAME = C.TABLE_NAME AND c.COLUMN_NAME ='ModifiedDate' WHERE T.TABLE_TYPE = 'BASE TABLE' ORDER BY T.TABLE_SCHEMA, T.TABLE_NAME; Method 2: Using DMV SELECT 'UPDATE ' + SCHEMA_NAME(t.schema_id) + '.' + t.name + ' SET ModifiedDate = GETDATE() WHERE ModifiedDate IS NULL;' FROM sys.tables AS t INNER JOIN sys.columns c ON t.OBJECT_ID = c.OBJECT_ID WHERE c.name ='ModifiedDate' ORDER BY SCHEMA_NAME(t.schema_id), t.name; Above scripts will create an UPDATE script which will do the task which is asked. We can pretty much the update script to any other SELECT statement and retrieve any other data as well. Click to Download Scripts Reference: Pinal Dave (http://blog.sqlauthority.com)  Filed under: PostADay, SQL, SQL Authority, SQL Joins, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology

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  • SQL SERVER – Reseting Identity Values for All Tables

    - by pinaldave
    Sometime email requesting help generates more questions than the motivation to answer them. Let us go over one of the such examples. I have converted the complete email conversation to chat format for easy consumption. I almost got a headache after around 20 email exchange. I am sure if you can read it and feel my pain. DBA: “I deleted all of the data from my database and now it contains table structure only. However, when I tried to insert new data in my tables I noticed that my identity values starts from the same number where they actually were before I deleted the data.” Pinal: “How did you delete the data?” DBA: “Running Delete in Loop?” Pinal: “What was the need of such need?” DBA: “It was my development server and I needed to repopulate the database.” Pinal: “Oh so why did not you use TRUNCATE which would have reset the identity of your table to the original value when the data got deleted? This will work only if you want your database to reset to the original value. If you want to set any other value this may not work.” DBA: (silence for 2 days) DBA: “I did not realize it. Meanwhile I regenerated every table’s schema and dropped the table and re-created it.” Pinal: “Oh no, that would be extremely long and incorrect way. Very bad solution.” DBA: “I understand, should I just take backup of the database before I insert the data and when I need, I can use the original backup to restore the database. This way I will have identity beginning with 1.” Pinal: “This going totally downhill. It is wrong to do so on multiple levels. Did you even read my earlier email about TRUNCATE.” DBA: “Yeah. I found it in spam folder.” Pinal: (I decided to stay silent) DBA: (After 2 days) “Can you provide me script to reseed identity for all of my tables to value 1 without asking further question.” Pinal: USE DATABASE; EXEC sp_MSForEachTable ' IF OBJECTPROPERTY(object_id(''?''), ''TableHasIdentity'') = 1 DBCC CHECKIDENT (''?'', RESEED, 1)' GO Our conversation ended here. If you have directly jumped to this statement, I encourage you to read the conversation one time. There is difference between reseeding identity value to 1 and reseeding it to original value – I will write an another blog post on this subject in future. 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 – Featuring in Call Me Maybe The Developer Way – Pluralsight Video

    - by pinaldave
    Is SQL boring? Not at all. SQL is fun – one has to know how to maximize the fun while working with SQL Server. Earlier I was invited to participate in the video Pluralsight. I am sure all of you know that I have authored 3 SQL Server Learning courses with Pluralsight – 1) SQL Server Q and A 2) SQL Server Performance Tuning and 3) SQL Server Indexing. Before I say anything I suggest all of you watch the following video. Make sure that you pay special attention after 0 minute and 36 seconds. What I can say about this. I am just fortunate to be part of the history in the making. There are more than 53 super cool celebrities in this video. In this just over 3 minute video there are so many story lines. I must congratulate director Megan and creative assistant Mari for excellent work. There are so many fun moments in this small video. Let me list my top five moments. @John_Papa ‘s dance at second 14 @julielerman playing with cute doggy The RACE between @josepheames and @bruthafish – the end is hilarious The black belt moment by @boedie @stwool relaxing on something strange! Well, this is indeed a great short film. This video demonstrates how cool is the culture of Pluralsight and how fun loving they are. A good organization provides an environment to its employees and partners to have maximum fun while they all become part of the success story. Hats off to Aaron Skonnard for producing this fun loving video. Well, after listening to this song for multiple times, I decided to give a call to Pluralsight. If you want, you can call them at +1 (801) 784-9032 or send an email to james-cole at pluralsight.com . What are your top five favorite moments? List it in comments and you may win Pluralsight subscription. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: About Me, PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology

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  • SQL SERVER – Storing 64-bit Unsigned Integer Value in Database

    - by Pinal Dave
    Here is a very interesting question I received in an email just another day. Some questions just are so good that it makes me wonder how come I have not faced it first hand. Anyway here is the question - “Pinal, I am migrating my database from MySQL to SQL Server and I have faced unique situation. I have been using Unsigned 64-bit integer in MySQL but when I try to migrate that column to SQL Server, I am facing an issue as there is no datatype which I find appropriate for my column. It is now too late to change the datatype and I need immediate solution. One chain of thought was to change the data type of the column from Unsigned 64-bit (BIGINT) to VARCHAR(n) but that will just change the data type for me such that I will face quite a lot of performance related issues in future. In SQL Server we also have the BIGINT data type but that is Signed 64-bit datatype. BIGINT datatype in SQL Server have range of -2^63 (-9,223,372,036,854,775,808) to 2^63-1 (9,223,372,036,854,775,807). However, my digit is much larger than this number. Is there anyway, I can store my big 64-bit Unsigned Integer without loosing much of the performance of by converting it to VARCHAR.” Very interesting question, for the sake of the argument, we can ask user that there should be no need of such a big number or if you are taking about identity column I really doubt that if your table will grow beyond this table. Here the real question which I found interesting was how to store 64-bit unsigned integer value in SQL Server without converting it to String data type. After thinking a bit, I found a fairly simple answer. I can use NUMERIC data type. I can use NUMERIC(20) datatype for 64-bit unsigned integer value, NUMERIC(10) datatype for 32-bit unsigned integer value and NUMERIC(5) datatype for 16-bit unsigned integer value. Numeric datatype supports 38 maximum of 38 precision. Now here is another thing to keep in mind. Using NUMERIC datatype will indeed accept the 64-bit unsigned integer but in future if you try to enter negative value, it will also allow the same. Hence, you will need to put any additional constraint over column to only accept positive integer there. Here is another big concern, SQL Server will store the number as numeric and will treat that as a positive integer for all the practical purpose. You will have to write in your application logic to interpret that as a 64-bit Unsigned Integer. On another side if you are using unsigned integers in your application, there are good chance that you already have logic taking care of the same. 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: SQL Datatype

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  • SQL SERVER – Fix: Error: 10920 Cannot drop user-defined function. It is being used as a resource governor classifier

    - by pinaldave
    If you have not read my SQL SERVER – Simple Example to Configure Resource Governor – Introduction to Resource Governor yesterday’s detailed primer on Resource Governor, I suggest you go ahead and read it before continuing this article. After reading the article the very first email I received was as follows: “Pinal, I configured resource governor on my development server and it worked fine with tests I ran. After doing some tests, I decided to remove the resource governor and as a first step I disabled it however, I was not able to drop the classification function during the process of the clean up. It was continuously giving me following error. Msg 10920, Level 16, State 1, Line 1 Cannot drop user-defined function myudfname. It is being used as a resource governor classifier. Would you please give me solution?” The original email was really this short and there is no other information. I am glad he has done experiments on development server and not on the production server. Production server must not be the playground of the experiments. I think I have covered the answer of this error in an earlier blog post. If the user disables the Resource Governor it is still not possible to drop the function because it can be enabled again and when enabled it can still use the same function. Here is the simple resolution of the how one can drop the classifier function (do this only if you are not going to use the function). The reason the classifier function can’t be dropped because it is associated with resource governor. Create a new classified function for your resource governor or just assign NULL as described in the following T-SQL Script and you will be able to drop the function without error. ALTER RESOURCE GOVERNOR WITH (CLASSIFIER_FUNCTION = NULL) GO ALTER RESOURCE GOVERNOR DISABLE GO DROP FUNCTION dbo.UDFClassifier GO I am glad that user asked me question instead of doing something radically different, which can leave the server in the unusable state. I am aware of this only method to avoid this error. Is there any better way to achieve the same? Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: PostADay, SQL, SQL Authority, SQL Error Messages, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology

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  • SQL SERVER – What is SSAS Tabular Data model and Why to use it – Part 2

    - by Pinal Dave
    In my last article, I talked about the basics of tabular data model and why use it. Then I demonstrated step by step creation of a basic tabular model project. In this part I’m going to throw some light on how to create measures and analyses in excel. If you look at the tabular project closely, you will notice that we have not defined any measure yet. So, in the first step we will define the measure first.  Open the solution and select the column you want to define as a measure. Then, click on the summation icon on the toolbar. You will see the aggregated results at the bottom of that column. You have also other choices as well like average, min, max, count and distinct count. After creating the required measures, we need to analyze our data in excel. To do this, click on the excel icon in the upper left corner of the toolbar. This will open your analysis in excel. Notice the pivot table field list here. I have highlighted the measures that we created in the earlier step. Now, we can use these measures in our analysis Now, we have to put the required fields in their respective places as column labels, row labels, Values and Report filter for analysis. See below snapshot for details, it shows region wise sales on a yearly basis You can even apply filters on the above analysis by placing the slicer field in report filter. In our example, we will take an English product name as a filter. You can use the filter as depicted in the below snapshot. Optionally, you can also use the slider to filter data more interactively. Further to improve our analysis, we can insert pivot charts That’s all for this time, in my next post I’m going to show in detail about how to create hierarchies, perspectives, KPI’s  and many more features. Author: Namita Sharma, Senior Corporate Trainer at Koenig Solutions. Reference: Pinal Dave (http://blog.SQLAuthority.com)Filed under: PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, T SQL Tagged: SSAS

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  • SQL SERVER – Use ROLL UP Clause instead of COMPUTE BY

    - by pinaldave
    Note: This upgrade was test performed on development server with using bits of SQL Server 2012 RC0 (which was available at in public) when this test was performed. However, SQL Server RTM (GA on April 1) is expected to behave similarly. I recently observed an upgrade from SQL Server 2005 to SQL Server 2012 with compatibility keeping at SQL Server 2012 (110). After upgrading the system and testing the various modules of the application, we quickly observed that few of the reports were not working. They were throwing error. When looked at carefully I noticed that it was using COMPUTE BY clause, which is deprecated in SQL Server 2012. COMPUTE BY clause is replaced by ROLL UP clause in SQL Server 2012. However there is no direct replacement of the code, user have to re-write quite a few things when using ROLL UP instead of COMPUTE BY. The primary reason is that how each of them returns results. In original code COMPUTE BY was resulting lots of result set but ROLL UP. Here is the example of the similar code of ROLL UP and COMPUTE BY. I personally find the ROLL UP much easier than COMPUTE BY as it returns all the results in single resultset unlike the other one. Here is the quick code which I wrote to demonstrate the said behavior. CREATE TABLE tblPopulation ( Country VARCHAR(100), [State] VARCHAR(100), City VARCHAR(100), [Population (in Millions)] INT ) GO INSERT INTO tblPopulation VALUES('India', 'Delhi','East Delhi',9 ) INSERT INTO tblPopulation VALUES('India', 'Delhi','South Delhi',8 ) INSERT INTO tblPopulation VALUES('India', 'Delhi','North Delhi',5.5) INSERT INTO tblPopulation VALUES('India', 'Delhi','West Delhi',7.5) INSERT INTO tblPopulation VALUES('India', 'Karnataka','Bangalore',9.5) INSERT INTO tblPopulation VALUES('India', 'Karnataka','Belur',2.5) INSERT INTO tblPopulation VALUES('India', 'Karnataka','Manipal',1.5) INSERT INTO tblPopulation VALUES('India', 'Maharastra','Mumbai',30) INSERT INTO tblPopulation VALUES('India', 'Maharastra','Pune',20) INSERT INTO tblPopulation VALUES('India', 'Maharastra','Nagpur',11 ) INSERT INTO tblPopulation VALUES('India', 'Maharastra','Nashik',6.5) GO SELECT Country,[State],City, SUM ([Population (in Millions)]) AS [Population (in Millions)] FROM tblPopulation GROUP BY Country,[State],City WITH ROLLUP GO SELECT Country,[State],City, [Population (in Millions)] FROM tblPopulation ORDER BY Country,[State],City COMPUTE SUM([Population (in Millions)]) BY Country,[State]--,City GO After writing this blog post I continuously feel that there should be some better way to do the same task. Is there any easier way to replace COMPUTE BY? 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 – A Brief Note on SET TEXTSIZE

    - by pinaldave
    Here is a small conversation I received. I thought though an old topic, indeed a thought provoking for the moment. Question: Is there any difference between LEFT function and SET TEXTSIZE? I really like this small but interesting question. The question does not specify the difference between usage or performance. Anyway we will quickly take a look at how TEXTSIZE works. You can run the following script to see how LEFT and SET TEXTSIZE works. USE TempDB GO -- Create TestTable CREATE TABLE MyTable (ID INT, MyText VARCHAR(MAX)) GO INSERT MyTable (ID, MyText) VALUES(1, REPLICATE('1234567890', 100)) GO -- Select Data SELECT ID, MyText FROM MyTable GO -- Using Left SELECT ID, LEFT(MyText, 10) MyText FROM MyTable GO -- Set TextSize SET TEXTSIZE 10; SELECT ID, MyText FROM MyTable; SET TEXTSIZE 2147483647 GO -- Clean up DROP TABLE MyTable GO Now let us see the usage result which we receive from both of the example. If you are going to ask what you should do – I really do not know. I can tell you where I will use either of the same. LEFT seems to be easy to use but again if you like to do extra work related to SET TEXTSIZE go for it. Here is how I will use SET TEXTSIZE. If I am selecting data from in my SSMS for testing or any other non production related work from a large table which has lots of columns with varchar data, I will consider using this statement to reduce the amount of the data which is retrieved in the result set. In simple word, for testing purpose I will use it. On the production server, there should be a specific reason to use the same. Here is my candid opinion – I do not think they can be directly comparable even though both of them give the exact same result. LEFT is applicable only on the column of a single SELECT statement. where it is used but it SET TEXTSIZE applies to all the columns in the SELECT and follow up SELECT statements till the SET TEXTSIZE is not modified again in the session. Uncomparable! I hope this sample example gives you idea how to use SET TEXTSIZE in your daily use. I would like to know your opinion about how and when do you use this feature. Please leave a comment. 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 – Get 2 of My Books FREE at Koenig Tech Day – Where Technologies Converge!

    - by pinaldave
    As a regular reader of my blog – you must be aware of that I love to write books and talk about various subjects of my book. The founders of Koenig Solutions are my very old friends, I know them for many years. They have been my biggest supporter of my books. Coming weekend they have a technology event at their Bangalore Location. Every attendee of the technology event will get a set of two books worth Rs. 450 – ‘SQL Server Interview Questions And Answers‘ and ‘SQL Wait Stats Joes 2 Pros‘. I am going to cover a couple of topics of the books and present  as well. I am very confident that every attendee will be having a great time. I will be covering following subjects: SQL Server Tricks and Tips for Blazing Fast Performance Slow Running Queries (SQL) 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 SQL Server has been set up. The session will focus on the ways of identifying problems that slow down SQL Servers, and tricks to fix them. Developers will walk out with scripts and knowledge that can be applied to their servers, immediately post the session. After the session is over – I will point to what exact location in the book where you can continue for the further learning. I am pretty excited, this is more like book reading but in entire different format. The one day event will cover four technologies in four separate interactive sessions on: Microsoft SQL Server Security VMware/Virtualization ASP.NET MVC Date of the event: Dec 15, 2012 9 AM to 6PM. Location of the event:  Koenig Solutions Ltd. # 47, 4th Block, 100 feet Road, 3rd Floor, Opp to Shanthi Sagar, Koramangala, Bangalore- 560034 Mobile : 09008096122 Office : 080- 41127140 Organizers have informed me that there are very limited seats for this event and technical session based on my book will start at Sharp 9 AM. If you show up late there are chances that you will not get any seats. Registration for the event is a MUST. Please visit this link for further information. 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, T SQL, Technology

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  • SQL – What ACID stands in the Database? – Contest to Win 24 Amazon Gift Cards and Joes 2 Pros 2012 Kit

    - by Pinal Dave
    We love puzzles. One of the brain’s main task is to solve puzzles. Sometime puzzles are very complicated (e.g Solving Rubik Cube or Sodoku)  and sometimes the puzzles are very simple (multiplying 4 by 8 or finding the shortest route while driving). It is always to solve puzzle and it creates an experience which humans are not able to forget easily. The best puzzles are the one where one has to do multiple things to reach to the final goal. Let us do something similar today. We will have a contest where you can participate and win something interesting. Contest This contest have two parts. Question 1: What ACID stands in the Database? This question seems very easy but here is the twist. Your answer should explain minimum one of the properties of the ACID in detail. If you wish you can explain all the four properties of the ACID but to qualify you need to explain minimum of the one properties. Question 2: What is the size of the installation file of NuoDB for any specific platform. You can answer this question following format – NuoDB installation file is of size __ MB for ___ Platform. Click on the Download the Link and download your installation file for NuoDB. You can post figure out the file size from the properties of the file. We have exciting content prizes for the winners. Prizes 1) 24 Amazon Gift Cards of USD 10 for next 24 hours. One card at every hour. (Open anywhere in the world) 2) One grand winner will get Joes 2 Pros SQL Server 2012 Training Kit worth USD 249. (Open where Amazon ship books). Amazon | 1 | 2 | 3 | 4 | 5  Rules The contest will be open till July 21, 2013. All the valid comments will be hidden till the result is announced. The winners will be announced on July 24, 2013. Hint: Download NuoDB  Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: PostADay, SQL, SQL Authority, SQL Puzzle, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology

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  • SQLAuthority News – Why I am Going to Attend #SQLPASS Summit 2012 – Seattle

    - by pinaldave
    I am going to Seattle I once again attend SQLPASS this year. This will be my fourth SQLPASS. Lots of people ask me why I am going to SQLPASS every year. Well there are so many different reasons for that. I go to SQLPASS because – I love it!  Here are few of the reasons I go to SQLPASS. Meet friends whom I have never met before Meet community at large – it is fun to hang around with like minded people Meet Rick Morelan – my book co-author and friend Attend various SQL Parties – there are so many parties around – see the list below Explore various new tools from various third party vendors Meet fellow Chapter Leaders and Regional Mentors And of course attend SQL Server Learning Sessions from industry known experts. The three-day event will be marked by a lot of learning, sharing, and networking, which will help me increase both my knowledge and contacts. PASS Summit provides me a golden opportunity to build my network as well as to identify and meet potential customers or employees. If I am a consultant or vendor who is looking for better career opportunities, PASS Summit is the perfect platform to meet and show my skills to my new potential customers and employers. Further, breakfasts, lunches, and evening receptions, which are included with registration, are meant to provide more and more networking opportunities. At PASS Summit, I gain not only new ideas but also inspire myself from top professionals and experts. Learning new things about SQL Server, interacting with different kinds of professionals, and sharing issues and solutions will definitely improve my understanding and turn me into a better SQL Server professional who can leverage and optimize SQL Server to improve business. I am going – are you joining? Note: This is re-blogged with modification from my 2 years old blog posts on a similar subject. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: About Me, Pinal Dave, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, SQLAuthority News, SQLServer, T SQL, Technology

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  • SQLAuthority News – Download Whitepaper – SQL Server Analysis Services to Hive

    - by pinaldave
    The SQL Server Analysis Service is a very interesting subject and I always have enjoyed learning about it. You can read my earlier article over here. Big Data is my new interest and I have been exploring it recently. During this weekend this blog post caught my attention and I enjoyed reading it. Big Data is the next big thing. The growth is predicted to be 60% per year till 2016. There is no single solution to the growing need of the big data available in the market right now as well there is no one solution in the business intelligence eco-system available as well. However, the need of the solution is ever increasing. I am personally Klout user. You can see my Klout profile over. I do understand what Klout is trying to achieve – a single place to measure the influence of the person. However, it works a bit mysteriously. There are plenty of social media available currently in the internet world. The biggest problem all the social media faces is that everybody opens an account but hardly people logs back in. To overcome this issue and have returned visitors Klout has come up with the system where visitors can give 5/10 K+ to other users in a particular area. Looking at all the activities Klout is doing it is indeed big consumer of the Big Data as well it is early adopter of the big data and Hadoop based system.  Klout has to 1 trillion rows of data to be analyzed as well have nearly thousand terabyte warehouse. Hive the language used for Big Data supports Ad-Hoc Queries using HiveQL there are always better solutions. The alternate solution would be using SQL Server Analysis Services (SSAS) along with HiveQL. As there is no direct method to achieve there are few common workarounds already in place. A new ODBC driver from Klout has broken through the limitation and SQL Server Relation Engine can be used as an intermediate stage before SSAS. In this white paper the same solutions have been discussed in the depth. The white paper discusses following important concepts. The Klout Big Data solution Big Data Analytics based on Analysis Services Hadoop/Hive and Analysis Services integration Limitations of direct connectivity Pass-through queries to linked servers Best practices and lessons learned This white paper discussed all the important concepts which have enabled Klout to go go to the next level with all the offerings as well helped efficiency by offering a few out of the box solutions. I personally enjoy reading this white paper and I encourage all of you to do so. SQL Server Analysis Services to Hive Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, SQL White Papers, T SQL, Technology

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  • SQL SERVER – SSAS – Multidimensional Space Terms and Explanation

    - by pinaldave
    I was presenting on SQL Server session at one of the Tech Ed On Road event in India. I was asked very interesting question during ‘Stump the Speaker‘ session. I am sharing the same with all of you over here. Question: Can you tell me in simple words what is dimension, member and other terms of multidimensional space? There is no simple example for it. This is extreme fundamental question if you know Analysis Service. Those who have no exposure to the same and have not yet started on this subject, may find it a bit difficult. I really liked his question so I decided to answer him there as well blog about the same over here. Answer: Here are the most important terms of multidimensional space – dimension, member, value, attribute and size. Dimension – It describes the point of interests for analysis. Member – It is one of the point of interests in the dimension. Value – It uniquely describes the member. Attribute – It is collection of multiple members. Size – It is total numbers for any dimension. Let us understand this further detail taking example of any space. I am going to take example of distance as a space in our example. Dimension – Distance is a dimension for us. Member – Kilometer – We can measure distance in Kilometer. Value – 4 – We can measure distance in the kilometer unit and the value of the unit can be 4. Attribute – Kilometer, Miles, Meter – The complete set of members is called attribute. Size – 100 KM – The maximum size decided for the dimension is called size. The same example can be also defined by using time space. Here is the example using time space. Dimension – Time Member – Date Value – 25 Attribute – 1, 2, 3…31 Size – 31 I hope it is clear enough that what are various multidimensional space and its terms. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Business Intelligence, PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology

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  • SQL SERVER – DELETE, TRUNCATE and RESEED Identity

    - by pinaldave
    Yesterday I had a headache answering questions to one of the DBA on the subject of Reseting Identity Values for All Tables. After talking to the DBA I realized that he has no clue about how the identity column behaves when there is DELETE, TRUNCATE or RESEED Identity is used. Let us run a small T-SQL Script. Create a temp table with Identity column beginning with value 11. The seed value is 11. USE [TempDB] GO -- Create Table CREATE TABLE [dbo].[TestTable]( [ID] [int] IDENTITY(11,1) NOT NULL, [var] [nchar](10) NULL ) ON [PRIMARY] GO -- Build sample data INSERT INTO [TestTable] VALUES ('val') GO When seed value is 11 the next value which is inserted has the identity column value as 11. – Select Data SELECT * FROM [TestTable] GO Effect of DELETE statement -- Delete Data DELETE FROM [TestTable] GO When the DELETE statement is executed without WHERE clause it will delete all the rows. However, when a new record is inserted the identity value is increased from 11 to 12. It does not reset but keep on increasing. -- Build sample data INSERT INTO [TestTable] VALUES ('val') GO -- Select Data SELECT * FROM [TestTable] Effect of TRUNCATE statement -- Truncate table TRUNCATE TABLE [TestTable] GO When the TRUNCATE statement is executed it will remove all the rows. However, when a new record is inserted the identity value is increased from 11 (which is original value). TRUNCATE resets the identity value to the original seed value of the table. -- Build sample data INSERT INTO [TestTable] VALUES ('val') GO -- Select Data SELECT * FROM [TestTable] GO Effect of RESEED statement If you notice I am using the reseed value as 1. The original seed value when I created table is 11. However, I am reseeding it with value 1. -- Reseed DBCC CHECKIDENT ('TestTable', RESEED, 1) GO When we insert the one more value and check the value it will generate the new value as 2. This new value logic is Reseed Value + Interval Value – in this case it will be 1+1 = 2. -- Build sample data INSERT INTO [TestTable] VALUES ('val') GO -- Select Data SELECT * FROM [TestTable] GO Here is the clean up act. -- Clean up DROP TABLE [TestTable] GO Question for you: If I reseed value with some random number followed by the truncate command on the table what will be the seed value of the table. (Example, if original seed value is 11 and I reseed the value to 1. If I follow up with truncate table what will be the seed value now? Here is the complete script together. You can modify it and find the answer to the above question. Please leave a comment with your answer. 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 – Biggest Concerns in a Data-Driven World

    - by Pinal Dave
    The ongoing chaos over Government Agency’s snooping has ignited a heated debate on privacy of personal data and its use by government and/or other institutions. It has created a feeling of disapproval and distrust among users. This incident proves to be a lesson for companies that are looking to leverage their business using a data driven approach. According to analysts, the goal of gathering personal information should be to deliver benefits to both the parties – the user as well as the data collector(government or business). Using data the right way is crucial, and companies need to deploy the right software applications and systems to ensure that their efforts are well-directed. However, there are various issues plaguing analysts regarding available software, which are highlighted below. According to a InformationWeek 2013 Survey of Analytics, Business Intelligence and Information Management where 541 business technology professionals contributed as respondents, it was discovered that the biggest concern was deemed to be the scarcity of expertise and high costs associated with the same. This concern was voiced by as many as 38% of the participants. A close second came out to be the issue of data warehouse appliance platforms being expensive, with 33% of those present believing it to be a huge roadblock. Another revelation made in this respect was that 31% professionals weren’t even sure how Data Analytics can create business opportunities for them. Another 17% shared that they found data platform technologies such as Hadoop and NoSQL technologies hard to learn. These results clearly pointed out that there are awareness and expertise issues that also need much attention. Unless the demand-supply gap of Business Intelligence professionals well versed in data analysis technologies is met, this divide is going to affect how companies make the most of their BI campaigns. One of the key action points that can be taken to salvage the situation, is to provide training on Data Analytics concepts. Koenig Solutions offer courses on many such technologies including a course on MCSE SQL Server 2012: BI Platform. So it’s time to brush up your skills and get down to work in a data driven world that awaits you ahead. 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 – QUOTED_IDENTIFIER ON/OFF Explanation and Example – Question on Real World Usage

    - by Pinal Dave
    This is a follow up blog post of SQL SERVER – QUOTED_IDENTIFIER ON/OFF and ANSI_NULL ON/OFF Explanation. I wrote that blog six years ago and I had plans that I will write a follow up blog post of the same. Today, when I was going over my to-do list and I was surprised that I had an item there which was six years old and I never got to do that. In the earlier blog post I wrote about exploitation of the Quoted Identifier and ANSI Null. In this blog post we will see a quick example of Quoted Identifier. However, before we continue this blog post, let us see a refresh what both of Quoted Identifider do. QUOTED IDENTIFIER ON/OFF This option specifies the setting for use of double quotes. When this is on, double quotation mark is used as part of the SQL Server identifier (object name). This can be useful in situations in which identifiers are also SQL Server reserved words. In simple words when we have QUOTED IDENTIFIER ON, anything which is wrapped in double quotes becomes an object. E.g. -- The following will work SET QUOTED_IDENTIFIER ON GO CREATE DATABASE "Test1" GO -- The following will throw an error about Incorrect syntax near 'Test2'. SET QUOTED_IDENTIFIER OFF GO CREATE DATABASE "Test2" GO This feature is particularly helpful when we are working with reserved keywords in SQL Server. For example if you have to create a database with the name VARCHAR or INT or DATABASE you may want to put double quotes around your database name and turn on quoted identifiers to create a database with the such name. Personally, I do not think so anybody will ever create a database with the reserve keywords intentionally, as it will just lead to confusion. Here is another example to give you further clarity about how Quoted Idenifier setting works with SELECT statement. -- The following will throw an error about Invalid column name 'Column'. SET QUOTED_IDENTIFIER ON GO SELECT "Column" GO -- The following will work SET QUOTED_IDENTIFIER OFF GO SELECT "Column" GO Personally, I always use the following method to create database as it works irrespective of what is the quoted identifier’s status. It always creates objects with my desire name whenever I would like to create. CREATE DATABASE [Test3] I believe the future of the quoted identifier on or off is useful in the real world when we have script generated from another database where this setting was ON and we have to now execute the same script again in our environment again. Question to you - I personally have never used this feature as I mentioned earlier. I believe this feature is there to support the scripts which are generated in another SQL Database or generate the script for other database. Do you have a real world scenario where we need to turn on or off Quoted Identifiers. Click to Download Scripts 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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  • Developer – Cross-Platform: Fact or Fiction?

    - by Pinal Dave
    This is a guest blog post by Jeff McVeigh. Jeff McVeigh is the general manager of Performance Client and Visual Computing within Intel’s Developer Products Division. His team is responsible for the development and delivery of leading software products for performance-centric application developers spanning Android*, Windows*, and OS* X operating systems. During his 17-year career at Intel, Jeff has held various technical and management positions in the fields of media, graphics, and validation. He also served as the technical assistant to Intel’s CTO. He holds 20 patents and a Ph.D. in electrical and computer engineering from Carnegie Mellon University. It’s not a homogenous world. We all know it. I have a Windows* desktop, a MacBook Air*, an Android phone, and my kids are 100% Apple. We used to have 2.5 kids, now we have 2.5 devices. And we all agree that diversity is great, unless you’re a developer trying to prioritize the limited hours in the day. Then it’s a series of trade-offs. Do we become brand loyalists for Google or Apple or Microsoft? Do we specialize on phones and tablets or still consider the 300M+ PC shipments a year when we make our decisions on where to spend our time and resources? We weigh the platform options, monetization opportunities, APIs, and distribution models. Too often, I see developers choose one platform, or write to the lowest common denominator, which limits their reach and market success. But who wants to be ?me too”? Cross-platform coding is possible in some environments, for some applications, for some level of innovation—but it’s not all-inclusive, yet. There are some tricks of the trade to develop cross-platform, including using languages and environments that ?run everywhere.” HTML5 is today’s answer for web-enabled platforms. However, it’s not a panacea, especially if your app requires the ultimate performance or native UI look and feel. There are other cross-platform frameworks that address the presentation layer of your application. But for those apps that have a preponderance of native code (e.g., highly-tuned C/C++ loops), there aren’t tons of solutions today to help with code reuse across these platforms using consistent tools and libraries. As we move forward with interim solutions, they’ll improve and become more robust, based, in no small part, on our input. What’s your answer to the cross-platform challenge? Are you fully invested in HTML5 now? What are your barriers? What’s your vision to navigate the cross-platform landscape?  Here is the link where you can head next and learn more about how to answer the questions I have asked: https://software.intel.com/en-us Republished with permission from here. Reference: Pinal Dave (http://blog.sqlauthority.com)Filed under: PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, T SQL Tagged: Intel

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  • SQL SERVER – Backup SQL databases to Box or SkyDrive

    - by Pinal Dave
    To ensure your SQL Server or Azure databases remain safe, you should backup your databases periodically. And it is important to store the backups in a reliable location. Microsoft SkyDrive currently offers 7GB free, Box offers 5GB free – both are reliable and it is simple to send your backups there. SQLBackupAndFTP in it’s latest version 9 added the option to backup to SkyDrive and Box ( in addition to local/network folder, NAS drive, FTP, Dropbox, Google Drive and Amazon S3). Just select the databases that you’d like to backup and select to store the backups in SkyDrive or Box. Below I will show you how to do it in details Select databases to backup First connect to your SQL Server or Azure Sql Database. Then select the databases you’d like to backup. Connect to SkyDrive or Box cloud If you have a free version of SQLBackupAndFTP Box destination is included, but SkyDrive destination will be disabled as it is available in the Standard version or above. Click “Try now” to get 30 days trial on all options On the “SkyDrive Settings” form you’ll need to authorize SQLBackupAndFTP to access your SkyDrive. Click “Authorize…” to open SkyDrive authorization page in your browser, sign in your to SkyDrive account and click at “Allow” . On the next page you will see the field with authorization code. Copy it to the clipboard. Box operation is just the same. After that return to SQLBackupAndFTP, paste the authorization code and click “OK” . After you are authorized, you can enter the path to a backup folder. SQLBackupAndFTP will create the folder if it does not exist. That’s all what has to be done to backup to SkyDrive or Box cloud.  You can now click on “Run Now” button to test this job. Conclusion Whatever is your preference for storing SQL backups, it is easy with SQLBackupAndFTP. Note that at the time of this writing they are running a very rare promotion on volume licenses: 5–9 licenses: 20% off 10–19 licenses: 35% off more than 20 licenses: 50% off Please let me know your favorite options for storing the backups. Reference: Pinal Dave (http://blog.sqlauthority.com)Filed under: PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, T SQL

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  • SQL SERVER – ERROR: FIX using Compatibility Level – Database diagram support objects cannot be installed because this database does not have a valid owner – Part 2

    - by pinaldave
    Earlier I wrote a blog post about how to resolve the error with database diagram. Today I faced the same error when I was dealing with a database which is upgraded from SQL Server 2005 to SQL Server 2008 R2. When I was searching for the solution online I ended up on my own earlier solution SQL SERVER – ERROR: FIX – Database diagram support objects cannot be installed because this database does not have a valid owner. I really found it interesting that I ended up on my own solution. However, the solution to the problem this time was a bit different. Let us see how we can resolve the same. Error: Database diagram support objects cannot be installed because this database does not have a valid owner. To continue, first use the Files page of the Database Properties dialog box or the ALTER AUTHORIZATION statement to set the database owner to a valid login, then add the database diagram support objects. Workaround / Fix / Solution : Follow the steps listed below and it should for sure solve your problem. (NOTE: Please try this for the databases upgraded from previous version. For everybody else you should just follow the steps mentioned here.) Select your database >> Right Click >> Select Properties Go to the Options In the Dropdown at right labeled “Compatibility Level” choose “SQL Server 2005(90)” Select FILE in left side of page In the OWNER box, select button which has three dots (…) in it Now select user ‘sa’ or NT AUTHORITY\SYSTEM and click OK. This will solve your problem. However, there is one very important note you must consider. When you change any database owner, there are always security related implications. I suggest you check your security policies before changing authorization. I did this to quickly solve my problem on my development server. If you are on production server, you may open yourself to potential security compromise. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: PostADay, SQL, SQL Authority, SQL Error Messages, SQL Query, SQL Server, SQL Tips and Tricks, T SQL

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  • git: How to move last N commits made to master, into own branch?

    - by amn
    Hi all, I have a repository where I had been working on master branch having last committed some 10 or so commits which I now wish were in another branch, as they describe work that I now consider experimental (i am still learning good git practices). Basically I would like to have these last 10 commits starting from a point in master to form another branch instead, so that I can have my master in a release state (which is what I strive for.) So, this is what I have (rightmost X is the last commit good for release): b--b (feature B) / X--X--X--Z--Z--Z--Z--Z--Z (master) \ a--a--a (feature A) You can see that both X and Z are on master, while I want commits marked by Z (my feature Z work) to lie on their own feature branch, and so that rightmost X is at the tip of master forming a good master branch tip. I guess this is what I want: b--b (feature B) / X--X--X (master) \ \ \ Z--Z--Z--Z--Z--Z (feature Z - the branch I want Z on) a--a--a (feature A) That way I will have my master always ready for release, and merge A, B and Z features when the time comes. Hope I am making sense here...

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  • SQLAuthority News – Pluralsight Course Review – Practices for Software Startups – Part 1 of 2

    - by pinaldave
    This is first part of the two part series of Practices for Software Startup Pluralsight Course. The course is written by Stephen Forte (Blog | Twitter). Stephen Forte is the Chief Strategy Officer of the venture backed company, Telerik, a leading vendor of developer and team productivity tools. Stephen is also a Certified Scrum Master, Certified Scrum Professional, PMP, and also speaks regularly at industry conferences around the world. He has written several books on application and database development.  Stephen is also a board member of the Scrum Alliance. Startups – Everybodies Dream Start-up companies are an important topic right now – everyone wants to start their own business.  It is also important to remember that all companies were a start up at one point – from your corner store to the giants like Microsoft and Apple.  Research proves that not every start-up succeeds, in fact, most will fail before their first year.  There are many reasons for this, and this could be due to the fact that there are many stages to a start-up company, and stumbling at any of these stages can lead to failure.  It is important to understand what makes a start-up company succeed at all its hurdles to become successful.  It is even important to define success.  For most start-ups this would mean becoming their own independently functioning company or to be bought out for a hefty profit by a larger company.  The idea of making a hefty profit by living your dream is extremely important, and you can even think of start-ups as the new craze.  That’s why studying them is so important – they are very popular, but things have changed a lot since their inception. Starting the Startups Beginning a start-up company used to be difficult, but now facilities and information is widely available, and it is much easier.  But that means it is much easier to fail, also.  Previously to start your own company, everything was planned and organized, resources were ensured and backed up before beginning; even the idea of starting your own business was a big thing.  Now anybody can do it, and the steps are simple and outlines everywhere – you can get online software and easily outsource , cloud source, or crowdsource a lot of your material.  But without the type of planning previously required, things can often go badly. New Products – New Ideas – New World There are so many fantastic new products, but they don’t reach success all the time.  I find start-up companies very interesting, and whenever I meet someone who is interested in the subject or already starting their own company, I always ask what they are doing, their plans, goals, market, etc.  I am sorry to say that in most cases, they cannot answer my questions.  It is true that many fantastic ideas fail because of bad decisions.  These bad decisions were not made intentionally, but people were simply unaware of what they should be doing.  This will always lead to failure.  But I am happy to say that all these issues can be gone because Pluralsight is now offering a course all about start-ups by Stephen Forte.  Stephen is a start up leader.  He has successfully started many companies and most are still going strong, or have gone on to even bigger and better things. Beginning Course on Startup I have always thought start-ups are a fascinating subject, and decided to take his course, but it is three hours long.  This would be hard to fit into my busy work day all at once, so I decided to do half of his course before my daughter wakes up, and the other half after she goes to sleep.  The course is divided into six modules, so this would be easy to do.  I began the first chapter early in the morning, at 5 am.  Stephen jumped right into the middle of the subject in the very first module – designing your business plan.  The first question you will have to answer to yourself, to others, and to investors is: What is your product and when will we be able to see it?  So a very important concept is a “minimal viable product.”  This means setting goals for yourself and your product.  We all have large dreams, but your minimal viable product doesn’t have to be your final vision at the very first.  For example: Apple is a giant company, but it is still evolving.  Steve Jobs didn’t envision the iPhone 6 at the very beginning.  He had to start at the first iPhone and do his market research, and the idea evolved into the technology you see now.  So for yourself, you should decide a beginning and stop point.  Do your market research.  Determine who you want to reach, what audience you want for your product.  You can have a great idea that simply will not work in the market, do need, bottlenecks, lack of resources, or competition.  There is a lot of research that needs to be done before you even write a business plan, and Stephen covers it in the very first chapter. The Team – Unique Key to Success After jumping right into the subject in the very first module, I wondered what Stephen could have in store for me for the rest of the course.  Chapter number two is building a team.  Having a team is important regardless of what your startup is.  You can be a true visionary with endless ideas and energy, but one person can still not do everything.  It is important to decide from the very beginning if you will have cofounders, team leaders, and how many employees you’ll need.  Even more important, you’ll need to decide what kind of team you want – what personalities, skills, and type of energy you want each of your employees to bring.  Do you want to have an A+ team with a B- idea, or do you have a B- idea that needs an A+ team to sell it?  Stephen asks all the hard questions!  I was especially impressed by his insight on developing.  You have to decide if you need developers, how many, and what their skills should be. I found this insight extremely useful for everyday usage, not just for start-up companies.  I would apply this kind of information in management at any position.  An amazing team will build an amazing product – and that doesn’t matter if you’re a start-up company or a small team working for a much larger business. Customer Development – The Ultimate Obective Chapter three was about customer development. According to Stephen, there are four different steps to develop a customer base.  The first question to ask yourself is if you are envisioning a large customer base buying a few products each, or a small, dedicated base that buys a lot of your product – quantity vs. Quality.  He also discusses how to earn, retain, and get more customers.  He also says that each customer should be placed in a different role – some will be like investors, who regularly spend with you and invest their money in your business.  It is then your job to take that investment and turn it into a better product in the future.  You need to deal with their money properly – think of it is as theirs as investors, not yours as profit.  At the end of this module I felt that only Stephen could provide this kind of insight, and then he listed all the resources he took his information from.  I have never seen a group of people so passionate about their customers. It was indeed a long day for me. In tomorrow’s part 2 we will discuss rest of the three module and also will see a quick video of the Practices for Software Startup Pluralsight Course. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: Best Practices, PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology

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  • MySQL – Scalability on Amazon RDS: Scale out to multiple RDS instances

    - by Pinal Dave
    Today, I’d like to discuss getting better MySQL scalability on Amazon RDS. The question of the day: “What can you do when a MySQL database needs to scale write-intensive workloads beyond the capabilities of the largest available machine on Amazon RDS?” Let’s take a look. In a typical EC2/RDS set-up, users connect to app servers from their mobile devices and tablets, computers, browsers, etc.  Then app servers connect to an RDS instance (web/cloud services) and in some cases they might leverage some read-only replicas.   Figure 1. A typical RDS instance is a single-instance database, with read replicas.  This is not very good at handling high write-based throughput. As your application becomes more popular you can expect an increasing number of users, more transactions, and more accumulated data.  User interactions can become more challenging as the application adds more sophisticated capabilities. The result of all this positive activity: your MySQL database will inevitably begin to experience scalability pressures. What can you do? Broadly speaking, there are four options available to improve MySQL scalability on RDS. 1. Larger RDS Instances – If you’re not already using the maximum available RDS instance, you can always scale up – to larger hardware.  Bigger CPUs, more compute power, more memory et cetera. But the largest available RDS instance is still limited.  And they get expensive. “High-Memory Quadruple Extra Large DB Instance”: 68 GB of memory 26 ECUs (8 virtual cores with 3.25 ECUs each) 64-bit platform High I/O Capacity Provisioned IOPS Optimized: 1000Mbps 2. Provisioned IOPs – You can get provisioned IOPs and higher throughput on the I/O level. However, there is a hard limit with a maximum instance size and maximum number of provisioned IOPs you can buy from Amazon and you simply cannot scale beyond these hardware specifications. 3. Leverage Read Replicas – If your application permits, you can leverage read replicas to offload some reads from the master databases. But there are a limited number of replicas you can utilize and Amazon generally requires some modifications to your existing application. And read-replicas don’t help with write-intensive applications. 4. Multiple Database Instances – Amazon offers a fourth option: “You can implement partitioning,thereby spreading your data across multiple database Instances” (Link) However, Amazon does not offer any guidance or facilities to help you with this. “Multiple database instances” is not an RDS feature.  And Amazon doesn’t explain how to implement this idea. In fact, when asked, this is the response on an Amazon forum: Q: Is there any documents that describe the partition DB across multiple RDS? I need to use DB with more 1TB but exist a limitation during the create process, but I read in the any FAQ that you need to partition database, but I don’t find any documents that describe it. A: “DB partitioning/sharding is not an official feature of Amazon RDS or MySQL, but a technique to scale out database by using multiple database instances. The appropriate way to split data depends on the characteristics of the application or data set. Therefore, there is no concrete and specific guidance.” So now what? The answer is to scale out with ScaleBase. Amazon RDS with ScaleBase: What you get – MySQL Scalability! ScaleBase is specifically designed to scale out a single MySQL RDS instance into multiple MySQL instances. Critically, this is accomplished with no changes to your application code.  Your application continues to “see” one database.   ScaleBase does all the work of managing and enforcing an optimized data distribution policy to create multiple MySQL instances. With ScaleBase, data distribution, transactions, concurrency control, and two-phase commit are all 100% transparent and 100% ACID-compliant, so applications, services and tooling continue to interact with your distributed RDS as if it were a single MySQL instance. The result: now you can cost-effectively leverage multiple MySQL RDS instance to scale out write-intensive workloads to an unlimited number of users, transactions, and data. Amazon RDS with ScaleBase: What you keep – Everything! And how does this change your Amazon environment? 1. Keep your application, unchanged – There is no change your application development life-cycle at all.  You still use your existing development tools, frameworks and libraries.  Application quality assurance and testing cycles stay the same. And, critically, you stay with an ACID-compliant MySQL environment. 2. Keep your RDS value-added services – The value-added services that you rely on are all still available. Amazon will continue to handle database maintenance and updates for you. You can still leverage High Availability via Multi A-Z.  And, if it benefits youra application throughput, you can still use read replicas. 3. Keep your RDS administration – Finally the RDS monitoring and provisioning tools you rely on still work as they did before. With your one large MySQL instance, now split into multiple instances, you can actually use less expensive, smallersmaller available RDS hardware and continue to see better database performance. Conclusion Amazon RDS is a tremendous service, but it doesn’t offer solutions to scale beyond a single MySQL instance. Larger RDS instances get more expensive.  And when you max-out on the available hardware, you’re stuck.  Amazon recommends scaling out your single instance into multiple instances for transaction-intensive apps, but offers no services or guidance to help you. This is where ScaleBase comes in to save the day. It gives you a simple and effective way to create multiple MySQL RDS instances, while removing all the complexities typically caused by “DIY” sharding andwith no changes to your applications . With ScaleBase you continue to leverage the AWS/RDS ecosystem: commodity hardware and value added services like read replicas, multi A-Z, maintenance/updates and administration with monitoring tools and provisioning. SCALEBASE ON AMAZON If you’re curious to try ScaleBase on Amazon, it can be found here – Download NOW. Reference: Pinal Dave (http://blog.sqlauthority.com)Filed under: MySQL, PostADay, SQL, SQL Authority, SQL Optimization, SQL Performance, SQL Query, SQL Server, SQL Tips and Tricks, T SQL

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  • Mysql Master Slave Replication on Large Database table (how to sync initial data)

    - by Brian Lovett
    We have a production server and a dev server. We have found that backups are nearly impossible on the production server because of the query volume we experience. So, we're looking at setting up replication with our dev server being the slave. This is ideal because we can afford to lock the tables on that server and additionally it will be nice to have up to date data for the developers. Now, the issues. The production server can't really be taken down or locked at this point, at least not easily. We have a high query volume and fairly large 30+ GB innodb tables. Both servers are running all innodb and are also both on mysql 5.1. What can we do to sync the data initially to get replication started? I've tried a few options, but so far, none have worked.

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