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  • SQL SERVER – Detect Virtual Log Files (VLF) in LDF

    - by pinaldave
    In one of the recent training engagements, I was asked if it true that there are multiple small log files in the large log file (LDF). I found this question very interesting as the answer is yes. Multiple small Virtual Log Files commonly known as VLFs together make an LDF file. The writing of the VLF is sequential and resulting in the writing of the LDF file is sequential as well. This leads to another talk that one does not need more than one log file in most cases. However, in short, you can use following DBCC command to know how many Virtual Log Files or VLFs are present in your log file. DBCC LOGINFO You can find the result of above query to something as displayed in following image. You can see the column which is marked as 2 which means it is active VLF and the one with 0 which is inactive VLF. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, SQL, SQL Authority, SQL Query, SQL Scripts, SQL Server, SQL Tips and Tricks, T SQL, Technology

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  • SQL SERVER – Enable PowerPivot Plugin in Excel

    - by pinaldave
    Recently I had interesting experience at one conference. My PowerPivot plugin got disabled and I had no clue how to enable the same. After while, I figured out how to enable the same. Once I got back from the event, I searched online and realize that many other people online are facing the same problem. Here is how I solved the problem. When I started Excel it did not load PowerPivot plugin. I found in option>> Add in the plug in to be disabled. I enabled the plugin and it worked very well. Let us see that with images. 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 Tagged: PowerPivot

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  • Programming doesn&rsquo;t have to be Magic

    - by Wes McClure
    In the show LOST, the Swan Station had a button that “had to be pushed” every 100 minutes to avoid disaster.  Several characters in the show took it upon themselves to have faith and religiously push the button, resetting the clock and averting the unknown “disaster”.  There are striking similarities in this story to the code we write every day.  Here are some common ones that I encounter: “I don’t know what it does but the application doesn’t work without it” “I added that code because I saw it in other similar places, I didn’t understand it, but thought it was necessary.” (for consistency, or to make things “work”) “An error message recommended it” “I copied that code” (and didn’t look at what it was doing) “It was suggested in a forum online and it fixed my problem so I left it” In all of these cases we haven’t done our due diligence to understand what the code we are writing is actually doing.  In the rush to get things done it seems like we’re willing to push any button (add any line of code) just to get our desired result and move on.  All of the above explanations are common things we encounter, and are valid ways to work through a problem we have, but when we find a solution to a task we are working on (whether a bug or a feature), we should take a moment to reflect on what we don’t understand.  Remove what isn’t necessary, comprehend and simplify what is.  Why is it detrimental to commit code we don’t understand? Perpetuates unnecessary code If you copy code that isn’t necessary, someone else is more likely to do so, especially peers Perpetuates tech debt Adding unnecessary code leads to extra code that must be understood, maintained and eventually cleaned up in longer lived projects Tech debt begets tech debt as other developers copy or use this code as guidelines in similar situations Increases maintenance How do we know the code is simplified if we don’t understand it? Perpetuates a lack of ownership Makes it seem ok to commit anything so long as it “gets the job done” Perpetuates the notion that programming is magic If we don’t take the time to understand every line of code we add, then we are contributing to the notion that it is simply enough to make the code work, regardless of how. TLDR Don’t commit code that you don’t understand, take the time to understand it, simplify it and then commit it!

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  • total number of magic square from 9 numbers

    - by Peeyush
    9 numbers need to be arranged in a magic number square. A magic number square is a square of numbers that is arranged such that every row and column has the same sum.(condition for diagonal has been relaxed) For example: 1 2 3 3 2 1 2 2 2 How do we calculate total number of distinct magic square from 9 numbers. Two magic number squares are distinct if they differ in value at one or more positions. For example, there is only one magic number square that can be made of 9 instances of the same number. e.g. for these 9 numbers { 4, 4, 4, 4, 4, 4, 4, 4, 4 }, answer should be 1. Also the complexity should be optimal. Do we need to iterate through all the permutations , discarding if a[0]+a[1]+a[2] %3!=0 such combinations ? moreover how do we remove duplicate magic square?

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  • SQL SERVER – SHRINKFILE and TRUNCATE Log File in SQL Server 2008

    - by pinaldave
    Note: Please read the complete post before taking any actions. This blog post would discuss SHRINKFILE and TRUNCATE Log File. The script mentioned in the email received from reader contains the following questionable code: “Hi Pinal, If you could remember, I and my manager met you at TechEd in Bangalore. We just upgraded to SQL Server 2008. One of our jobs failed as it was using the following code. The error was: Msg 155, Level 15, State 1, Line 1 ‘TRUNCATE_ONLY’ is not a recognized BACKUP option. The code was: DBCC SHRINKFILE(TestDBLog, 1) BACKUP LOG TestDB WITH TRUNCATE_ONLY DBCC SHRINKFILE(TestDBLog, 1) GO I have modified that code to subsequent code and it works fine. But, are there other suggestions you have at the moment? USE [master] GO ALTER DATABASE [TestDb] SET RECOVERY SIMPLE WITH NO_WAIT DBCC SHRINKFILE(TestDbLog, 1) ALTER DATABASE [TestDb] SET RECOVERY FULL WITH NO_WAIT GO Configuration of our server and system is as follows: [Removed not relevant data]“ An email like this that suddenly pops out in early morning is alarming email. Because I am a dead, busy mind, so I had only one min to reply. I wrote down quickly the following note. (As I said, it was a single-minute email so it is not completely accurate). Here is that quick email shared with all of you. “Hi Mr. DBA [removed the name] Thanks for your email. I suggest you stop this practice. There are many issues included here, but I would list two major issues: 1) From the setting database to simple recovery, shrinking the file and once again setting in full recovery, you are in fact losing your valuable log data and will be not able to restore point in time. Not only that, you will also not able to use subsequent log files. 2) Shrinking file or database adds fragmentation. There are a lot of things you can do. First, start taking proper log backup using following command instead of truncating them and losing them frequently. BACKUP LOG [TestDb] TO  DISK = N'C:\Backup\TestDb.bak' GO Remove the code of SHRINKING the file. If you are taking proper log backups, your log file usually (again usually, special cases are excluded) do not grow very big. There are so many things to add here, but you can call me on my [phone number]. Before you call me, I suggest for accuracy you read Paul Randel‘s two posts here and here and Brent Ozar‘s Post here. Kind Regards, Pinal Dave” I guess this post is very much clear to you. Please leave your comments here. As mentioned, this is a very huge subject; I have just touched a tip of the ice-berg and have tried to point to authentic knowledge. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, SQL, SQL Authority, SQL Backup and Restore, SQL Data Storage, SQL Query, SQL Scripts, SQL Server, SQL Tips and Tricks, T SQL, Technology

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  • SQLAuthority News – SQL Server Technology Evangelists and Evangelism

    - by pinaldave
    This is the exact conversation that I had with three people during the recent SQL Server Public Training. Person 1: “Are you an SQL Server Evangelist?” Pinal : “No, but Vinod Kumar is.” Person 1: “Who are you?” Person 2: “He is Pinal, haha!” Person 1: “I know that, but don’t you evangelize SQL Server Technology?” Pinal : “Hmm… I do that…” Person 1: “In that case, why don’t you call yourself an Evangelist?” Pinal : “…! …” Person 2: “Good Question! Who are you Pinal?” Pinal : “I think you are asking my title, is that correct?” Person 1: “Maybe.” Pinal : “I am a Mentor, and I work for Solid Quality Mentors.” Person 2: “I have seen you listing yourself as the Founder of SQLAuthority.com… so…” Pinal : “Yeah that’s true.” Person 3: “Let me summarize what these people are asking. What they are asking is that you can have multiple titles, so is being an evangelist one of your titles or not?” Pinal : “Well, I am an SQL Server MVP and lots of people say that we are also evangelists of technology. In fact,  we are all evangelists of technology, aren’t we?” Person 1: “So let me come back to my original topic: If you are an SQL Server Evangelist, then what is this evangelism?” Person 2: “And who is Vinod Kumar – I have heard about him a lot.” Pinal : “Oh okay. Now I got it. Let me explain …” The answer was quite long but since this conversation, I have been thinking about the words “evangelist” and “evangelism.” I think being an evangelist is one of the most respected jobs in the world and to do this job one must bear lots of responsibilities. There were two questions asked to me, so let me answer both one by one. Who is Vinod Kumar? Vinod Kumar is a Technology Evangelist for Microsoft and one of the most respected persons in the SQL Server Community in India. Let me copy-paste my note from the previous TechEd India 2010 article. “I attended 2 sessions of Vinod Kumar. Vinod is a natural storyteller so there was no doubt that his sessions would be jam-packed. People attended his sessions simply because Vinod was the best speaker in the event. He did not have a single time that disappointed audience; he is truly a good speaker. He knows his stuff very well. I personally do not think that in India he can be compared to anyone for SQL.” Pinal Dave and Vinod Kumar What is Technology Evangelism? Here I am listing three posts written by Vinod Kumar, wherein he talks about Technology Evangelism and Technology Evangelist in an in-depth manner. They are highly-regarded articles in the Community. Evangelism beyond boundaries with an Evangelists !!! Technology Evangelism Demystified New face of Online Technology Evangelism I strongly recommend reading them all. These are wonderful blog posts. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: About Me, MVP, Pinal Dave, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, SQLAuthority News, T SQL, Technology

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  • SQL SERVER – Guest Post – Glenn Berry – Wait Type – Day 26 of 28

    - by pinaldave
    Glenn Berry works as a Database Architect at NewsGator Technologies in Denver, CO. He is a SQL Server MVP, and has a whole collection of Microsoft certifications, including MCITP, MCDBA, MCSE, MCSD, MCAD, and MCTS. He is also an Adjunct Faculty member at University College – University of Denver, where he has been teaching since 2000. He is one wonderful blogger and often blogs at here. I am big fan of the Dynamic Management Views (DMV) scripts of Glenn. His script are extremely popular and the reality is that he has inspired me to start this series with his famous DMV which I have mentioned in very first  wait stats blog post (I had forgot to request his permission to re-use the script but when asked later on his whole hearty approved it). Here is is his excellent blog post on this subject of wait stats: Analyzing cumulative wait stats in SQL Server 2005 and above has become a popular and effective technique for diagnosing performance issues and further focusing your troubleshooting and diagnostic  efforts.  Rather than just guessing about what resource(s) that SQL Server is waiting on, you can actually find out by running a relatively simple DMV query. Once you know what resources that SQL Server is spending the most time waiting on, you can run more specific queries that focus on that resource to get a better idea what is causing the problem. I do want to throw out a few caveats about using wait stats as a diagnostic tool. First, they are most useful when your SQL Server instance is experiencing performance problems. If your instance is running well, with no indication of any resource pressure from other sources, then you should not worry that much about what the top wait types are. SQL Server will always be waiting on some resource, but many wait types are quite benign, and can be safely ignored. In spite of this, I quite often see experienced DBAs obsessing over the top wait type, even when their SQL Server instance is running extremely well. Second, I often see DBAs jump to the wrong conclusion based on seeing a particular well-known wait type. A good example is CXPACKET waits. People typically jump to the conclusion that high CXPACKET waits means that they should immediately change their instance-level MADOP setting to 1. This is not always the best solution. You need to consider your workload type, and look carefully for any important “missing” indexes that might be causing the query optimizer to use a parallel plan to compensate for the missing index. In this case, correcting the index problem is usually a better solution than changing MAXDOP, since you are curing the disease rather than just treating the symptom. Finally, you should get in the habit of clearing out your cumulative wait stats with the  DBCC SQLPERF(‘sys.dm_os_wait_stats’, CLEAR); command. This is especially important if you have made an configuration or index changes, or if your workload has changed recently. Otherwise, your cumulative wait stats will be polluted with the old stats from weeks or months ago (since the last time SQL Server was started or the stats were cleared).  If you make a change to your SQL Server instance, or add an index, you should clear out your wait stats, and then wait a while to see what your new top wait stats are. At any rate, enjoy Pinal Dave’s series on Wait Stats. This blog post has been written by Glenn Berry (Twitter | Blog) Read all the post in the Wait Types and Queue series. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, PostADay, Readers Contribution, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, SQL Wait Stats, SQL Wait Types, T SQL, Technology

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  • Aligning Numbered Bullet Points in Word 2007

    - by FrustratedwithWord
    I am putting together a very large business manual which incorporates numbered headings, steps to follow, diagrams, etc. When using the bullet points, they align perfectly as I work through the processes. However when I include a diagram, or something different from the "norm" of text, the alignment changes. I would like all the bullet points to be aligned in the whole document regardless of where they appear in the document. Is there a way to save the settings so that the bullets always appear in the same position? Currently I am having to reset the indents by dragging the tabs on the ruler. This will be a large document, so I don't want to manually adjust the numbered bullets every time. Help would be greatly appreciated. Thanks very much.

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  • SQL SERVER – 2011 – Wait Type – Day 25 of 28

    - by pinaldave
    Since the beginning of the series, I have been getting the following question again and again: “What are the changes in SQL Server 2011 – Denali with respect to Wait Types?” SQL Server 2011 – Denali is yet to be released, and making statements on the subject will be inappropriate. Denali CTP1 has been released so I suggest that all of you download the same and experiment on it. I quickly compared the wait stats of SQL Server 2008 R2 and Denali (CTP1) and found the following changes: Wait Types Exists in SQL Server 2008 R2 and Not Exists in SQL Server 2011 “Denali” SOS_RESERVEDMEMBLOCKLIST SOS_LOCALALLOCATORLIST QUERY_WAIT_ERRHDL_SERVICE QUERY_ERRHDL_SERVICE_DONE XE_PACKAGE_LOCK_BACKOFF Wait Types Exists in SQL Server 2011 and Not Exists in SQL Server 2008 SLEEP_MASTERMDREADY SOS_MEMORY_TOPLEVELBLOCKALLOCATOR SOS_PHYS_PAGE_CACHE FILESTREAM_WORKITEM_QUEUE FILESTREAM_FILE_OBJECT FILESTREAM_FCB FILESTREAM_CACHE XE_CALLBACK_LIST PWAIT_MD_RELATION_CACHE PWAIT_MD_SERVER_CACHE PWAIT_MD_LOGIN_STATS DISPATCHER_PRIORITY_QUEUE_SEMAPHORE FT_PROPERTYLIST_CACHE SECURITY_KEYRING_RWLOCK BROKER_TRANSMISSION_WORK BROKER_TRANSMISSION_OBJECT BROKER_TRANSMISSION_TABLE BROKER_DISPATCHER BROKER_FORWARDER UCS_MANAGER UCS_TRANSPORT UCS_MEMORY_NOTIFICATION UCS_ENDPOINT_CHANGE UCS_TRANSPORT_STREAM_CHANGE QUERY_TASK_ENQUEUE_MUTEX DBCC_SCALE_OUT_EXPR_CACHE PWAIT_ALL_COMPONENTS_INITIALIZED PREEMPTIVE_SP_SERVER_DIAGNOSTICS SP_SERVER_DIAGNOSTICS_SLEEP SP_SERVER_DIAGNOSTICS_INIT_MUTEX AM_INDBUILD_ALLOCATION QRY_PARALLEL_THREAD_MUTEX FT_MASTER_MERGE_COORDINATOR PWAIT_RESOURCE_SEMAPHORE_FT_PARALLEL_QUERY_SYNC REDO_THREAD_PENDING_WORK REDO_THREAD_SYNC COUNTRECOVERYMGR HADR_DB_COMMAND HADR_TRANSPORT_SESSION HADR_CLUSAPI_CALL PWAIT_HADR_CHANGE_NOTIFIER_TERMINATION_SYNC PWAIT_HADR_ACTION_COMPLETED PWAIT_HADR_OFFLINE_COMPLETED PWAIT_HADR_ONLINE_COMPLETED PWAIT_HADR_FORCEFAILOVER_COMPLETED PWAIT_HADR_WORKITEM_COMPLETED HADR_WORK_POOL HADR_WORK_QUEUE HADR_LOGCAPTURE_SYNC LOGPOOL_CACHESIZE LOGPOOL_FREEPOOLS LOGPOOL_REPLACEMENTSET LOGPOOL_CONSUMERSET LOGPOOL_MGRSET LOGPOOL_CONSUMER LOGPOOLREFCOUNTEDOBJECT_REFDONE HADR_SYNC_COMMIT HADR_AG_MUTEX PWAIT_SECURITY_CACHE_INVALIDATION PWAIT_HADR_SERVER_READY_CONNECTIONS HADR_FILESTREAM_MANAGER HADR_FILESTREAM_BLOCK_FLUSH HADR_FILESTREAM_IOMGR XDES_HISTORY XDES_SNAPSHOT HADR_FILESTREAM_IOMGR_IOCOMPLETION UCS_SESSION_REGISTRATION ENABLE_EMPTY_VERSIONING HADR_DB_OP_START_SYNC HADR_DB_OP_COMPLETION_SYNC HADR_LOGPROGRESS_SYNC HADR_TRANSPORT_DBRLIST HADR_FAILOVER_PARTNER XDESTSVERMGR GHOSTCLEANUPSYNCMGR HADR_AR_UNLOAD_COMPLETED HADR_PARTNER_SYNC HADR_DBSTATECHANGE_SYNC We already know that Wait Types and Wait Stats are going to be the next big thing in the next version of SQL Server. So now I am eagerly waiting to dig deeper in the wait stats. Read all the post in the Wait Types and Queue series. Note: The information presented here is from my experience and there is no way that I claim it to be accurate. I suggest reading Book OnLine for further clarification. All the discussion of Wait Stats in this blog is generic and varies from system to system. It is recommended that you test this on a development server before implementing it to a production server. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, SQL Wait Stats, SQL Wait Types, T SQL, Technology

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  • SQL SERVER – Generate Report for Index Physical Statistics – SSMS

    - by pinaldave
    Few days ago, I wrote about SQL SERVER – Out of the Box – Activity and Performance Reports from SSSMS (Link). A user asked me a question regarding if we can use similar reports to get the detail about Indexes. Yes, it is possible to do the same. There are similar type of reports are available at Database level, just like those available at the Server Instance level. You can right click on Database name and click Reports. Under Standard Reports, you will find following reports. Disk Usage Disk Usage by Top Tables Disk Usage by Table Disk Usage by Partition Backup and Restore Events All Transactions All Blocking Transactions Top Transactions by Age Top Transactions by Blocked Transactions Count Top Transactions by Locks Count Resource Locking Statistics by Objects Object Execute Statistics Database Consistency history Index Usage Statistics Index Physical Statistics Schema Change history User Statistics Select the Reports with name Index Physical Statistics. Once click, a report containing all the index names along with other information related to index will be visible, e.g. Index Type and number of partitions. One column that caught my interest was Operation Recommended. In some place, it suggested that index needs to be rebuilt. It is also possible to click and expand the column of partitions and see additional details about index as well. DBA and Developers who just want to have idea about how your index is and its physical statistics can use this tool. Click to Enlarge Note: Please note that I will rebuild my indexes just because this report is recommending it. There are many other parameters you need to consider before rebuilding indexes. However, this tool gives you the accurate stats of your index and it can be right away exported to Excel or PDF writing by clicking on the report. Reference : Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, SQL, SQL Authority, SQL Index, SQL Optimization, SQL Performance, SQL Query, SQL Server, SQL Server Management Studio, SQL Tips and Tricks, SQL Utility, T SQL, Technology

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  • SQL SERVER – Four Posts on Removing the Bookmark Lookup – Key Lookup

    - by pinaldave
    In recent times I have observed that not many people have proper understanding of what is bookmark lookup or key lookup. Increasing numbers of the questions tells me that this is something developers are encountering every single day but have no idea how to deal with it. I have previously written three articles on this subject. I want to point all of you looking for further information on the same post. SQL SERVER – Query Optimization – Remove Bookmark Lookup – Remove RID Lookup – Remove Key Lookup SQL SERVER – Query Optimization – Remove Bookmark Lookup – Remove RID Lookup – Remove Key Lookup – Part 2 SQL SERVER – Query Optimization – Remove Bookmark Lookup – Remove RID Lookup – Remove Key Lookup – Part 3 SQL SERVER – Interesting Observation – Execution Plan and Results of Aggregate Concatenation Queries In one of my recent class we had in depth conversation about what are the alternative of creating covering indexes to remove the bookmark lookup. I really want to this question open to all of you and see what community thinks about the same. Is there any other way then creating covering index or included index to remove his expensive keylookup? Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: Pinal Dave, SQL, SQL Authority, SQL Backup and Restore, SQL Index, SQL Optimization, SQL Performance, SQL Query, SQL Scripts, SQL Server, SQL Tips and Tricks, SQLAuthority News, SQLServer, T SQL, Technology

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  • SQL SERVER – Subquery or Join – Various Options – SQL Server Engine knows the Best

    - by pinaldave
    This is followup post of my earlier article SQL SERVER – Convert IN to EXISTS – Performance Talk, after reading all the comments I have received I felt that I could write more on the same subject to clear few things out. First let us run following four queries, all of them are giving exactly same resultset. USE AdventureWorks GO -- use of = SELECT * FROM HumanResources.Employee E WHERE E.EmployeeID = ( SELECT EA.EmployeeID FROM HumanResources.EmployeeAddress EA WHERE EA.EmployeeID = E.EmployeeID) GO -- use of in SELECT * FROM HumanResources.Employee E WHERE E.EmployeeID IN ( SELECT EA.EmployeeID FROM HumanResources.EmployeeAddress EA WHERE EA.EmployeeID = E.EmployeeID) GO -- use of exists SELECT * FROM HumanResources.Employee E WHERE EXISTS ( SELECT EA.EmployeeID FROM HumanResources.EmployeeAddress EA WHERE EA.EmployeeID = E.EmployeeID) GO -- Use of Join SELECT * FROM HumanResources.Employee E INNER JOIN HumanResources.EmployeeAddress EA ON E.EmployeeID = EA.EmployeeID GO Let us compare the execution plan of the queries listed above. Click on image to see larger image. It is quite clear from the execution plan that in case of IN, EXISTS and JOIN SQL Server Engines is smart enough to figure out what is the best optimal plan of Merge Join for the same query and execute the same. However, in the case of use of Equal (=) Operator, SQL Server is forced to use Nested Loop and test each result of the inner query and compare to outer query, leading to cut the performance. Please note that here I no mean suggesting that Nested Loop is bad or Merge Join is better. This can very well vary on your machine and amount of resources available on your computer. When I see Equal (=) operator used in query like above, I usually recommend to see if user can use IN or EXISTS or JOIN. As I said, this can very much vary on different system. What is your take in above query? I believe SQL Server Engines is usually pretty smart to figure out what is ideal execution plan and use it. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, SQL, SQL Authority, SQL Joins, SQL Optimization, SQL Performance, SQL Query, SQL Scripts, SQL Server, SQL Tips and Tricks, T SQL, Technology

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  • SQL SERVER – Subquery or Join – Various Options – SQL Server Engine Knows the Best – Part 2

    - by pinaldave
    This blog post is part 2 of the earlier written article SQL SERVER – Subquery or Join – Various Options – SQL Server Engine knows the Best by Paulo R. Pereira. Paulo has left excellent comment to earlier article once again proving the point that SQL Server Engine is smart enough to figure out the best plan itself and uses the same for the query. Let us go over his comment as he has posted. “I think IN or EXISTS is the best choice, because there is a little difference between ‘Merge Join’ of query with JOIN (Inner Join) and the others options (Left Semi Join), and JOIN can give more results than IN or EXISTS if the relationship is 1:0..N and not 1:0..1. And if I try use NOT IN and NOT EXISTS the query plan is different from LEFT JOIN too (Left Anti Semi Join vs. Left Outer Join + Filter). So, I found a case where EXISTS has a different query plan than IN or ANY/SOME:” USE AdventureWorks GO -- use of SOME SELECT * FROM HumanResources.Employee E WHERE E.EmployeeID = SOME ( SELECT EA.EmployeeID FROM HumanResources.EmployeeAddress EA UNION ALL SELECT EA.EmployeeID FROM HumanResources.EmployeeDepartmentHistory EA ) -- use of IN SELECT * FROM HumanResources.Employee E WHERE E.EmployeeID IN ( SELECT EA.EmployeeID FROM HumanResources.EmployeeAddress EA UNION ALL SELECT EA.EmployeeID FROM HumanResources.EmployeeDepartmentHistory EA ) -- use of EXISTS SELECT * FROM HumanResources.Employee E WHERE EXISTS ( SELECT EA.EmployeeID FROM HumanResources.EmployeeAddress EA UNION ALL SELECT EA.EmployeeID FROM HumanResources.EmployeeDepartmentHistory EA ) When looked into execution plan of the queries listed above indeed we do get different plans for queries and SQL Server Engines creates the best (least cost) plan for each query. Click on image to see larger images. Thanks Paulo for your wonderful contribution. Reference : Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, Readers Contribution, SQL, SQL Authority, SQL Joins, SQL Optimization, SQL Performance, SQL Query, SQL Scripts, SQL Server, SQL Tips and Tricks, T SQL, Technology

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  • SQL SERVER – Concat Strings in SQL Server using T-SQL – SQL in Sixty Seconds #035 – Video

    - by pinaldave
    Concatenating  string is one of the most common tasks in SQL Server and every developer has to come across it. We have to concat the string when we have to see the display full name of the person by first name and last name. In this video we will see various methods to concatenate the strings. SQL Server 2012 has introduced new function CONCAT which concatenates the strings much efficiently. When we concat values with ‘+’ in SQL Server we have to make sure that values are in string format. However, when we attempt to concat integer we have to convert the integers to a string or else it will throw an error. However, with the newly introduce the function of CONCAT in SQL Server 2012 we do not have to worry about this kind of issue. It concatenates strings and integers without casting or converting them. You can specify various values as a parameter to CONCAT functions and it concatenates them together. Let us see how to concat the values in Sixty Seconds: Here is the script which is used in the video. -- Method 1: Concatenating two strings SELECT 'FirstName' + ' ' + 'LastName' AS FullName -- Method 2: Concatenating two Numbers SELECT CAST(1 AS VARCHAR(10)) + ' ' + CAST(2 AS VARCHAR(10)) -- Method 3: Concatenating values of table columns SELECT FirstName + ' ' + LastName AS FullName FROM AdventureWorks2012.Person.Person -- Method 4: SQL Server 2012 CONCAT function SELECT CONCAT('FirstName' , ' ' , 'LastName') AS FullName -- Method 5: SQL Server 2012 CONCAT function SELECT CONCAT('FirstName' , ' ' , 1) AS FullName Related Tips in SQL in Sixty Seconds: SQL SERVER – Concat Function in SQL Server – SQL Concatenation String Function – CONCAT() – A Quick Introduction 2012 Functions – FORMAT() and CONCAT() – An Interesting Usage A Quick Trick about SQL Server 2012 CONCAT Function – PRINT A Quick Trick about SQL Server 2012 CONCAT function What would you like to see in the next SQL in Sixty Seconds video? Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: Database, Pinal Dave, PostADay, SQL, SQL Authority, SQL in Sixty Seconds, SQL Query, SQL Scripts, SQL Server, SQL Server Management Studio, SQL Tips and Tricks, T SQL, Technology, Video Tagged: Excel

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  • SQL SERVER – Activity Monitor and Performance Issue

    - by pinaldave
    We had wonderful SQLAuthority News – Community Tech Days – December 11, 2010 event yesterday. After the event, we had meeting among Jacob Sebastian, Vinod Kumar, Rushabh Mehta and myself. We all were sharing our experience about performance tuning consultations. During the conversation, Jacob has shared wonderful story of his recent observation. The story is very small but the moral of the story is very important. The story is about a client, who had continuously performance issues. Client used Activity Monitor (Read More: SQL SERVER – 2008 – Location of Activity Monitor – Where is SQL Serve Activity Monitor Located) to check the performance issues. The pattern of the performance issues was very much common all the time. Every time, after a while the computer stopped responding. After doing in-depth performance analysis, Jacob realized that client once opened activity monitor never closed it. The same activity monitor itself is very expensive process. The tool, which helped to debug the performance issues, also helped (negatively) to bring down the server. After closing the activity monitor which was open for long time, the server did not have performance issues. Moral of the story: Activity Monitor is great tool but use it with care and close it when not needed. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Best Practices, Pinal Dave, SQL, SQL Authority, SQL Optimization, SQL Performance, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology

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  • SQL SERVER – Standard Reports from SQL Server Management Studio – SQL in Sixty Seconds #016 – Video

    - by pinaldave
    SQL Server management Studio 2012 is wonderful tool and has many different features. Many times, an average user does not use them as they are not aware about these features. Today, we will learn one such feature. SSMS comes with many inbuilt performance and activity reports, but we do not use it to the full potential. Connect to SQL Server Node >> Right Click on it >> Go to Reports >> Click on Standard Reports >> Pick Any Report. Please note that some of the reports can be IO intensive and not suggested to run during business hours! More on Standard Reports: SQL SERVER – Out of the Box – Activity and Performance Reports from SSSMS SQL SERVER – Generate Report for Index Physical Statistics – SSMS SQL SERVER – Configure Management Data Collection in Quick Steps I encourage you to submit your ideas for SQL in Sixty Seconds. We will try to accommodate as many as we can. If we like your idea we promise to share with you educational material. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: Database, Pinal Dave, PostADay, SQL, SQL Authority, SQL in Sixty Seconds, SQL Query, SQL Scripts, SQL Server, SQL Server Management Studio, SQL Tips and Tricks, T SQL, Technology, Video

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  • SQL SERVER – Concat Function in SQL Server – SQL Concatenation

    - by pinaldave
    Earlier this week, I was delivering Advanced BI training on the subject of “SQL Server 2008 R2″. I had great time delivering the session. During the session, we talked about SQL Server 2010 Denali. Suddenly one of the attendees suggested his displeasure for the product. He said, even though, SQL Server is now in moving very fast and have proved many times a good enterprise solution, it does not have some basic functions. I naturally asked him for example and he suggested CONCAT() which exists in MySQL and Oracle. The answer is very simple – the equalent function in SQL Server to CONCAT() is ‘+’ (plus operator without quotes). Method 1: Concatenating two strings SELECT 'FirstName' + ' ' + 'LastName' AS FullName Method 2: Concatenating two Numbers SELECT CAST(1 AS VARCHAR(10)) + 'R' + CAST(2 AS VARCHAR(10)) Method 3: Concatenating values from table columns SELECT FirstName + ' ' + LastName FROM AdventureWorks.Person.Contact Well, this may look very simple but sometime it is very difficult to find the information for simple things only. Do you have any such example which you would like to share with community? Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: Pinal Dave, SQL, SQL Authority, SQL Query, SQL Scripts, SQL Server, SQL String, SQL Tips and Tricks, T SQL, Technology

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  • SQLAuthority News – Three Posts on Reporting – T-SQL Tuesday #005

    - by pinaldave
    If you are following my blog, you already know that I am more of “T-SQL and Performance Tuning” type of person. I do have a good understanding of Business Intelligence suit and I also do certain training sessions on the same subject. When I was writing the blog post for T-SQL Tuesday #005 – Reporting, I realized that I have written a post that clearly explains how to generate reports using SQL Server Management Studio. Here is a quick recap on how one can use SSMS and out-of-the-box reports which can help many developers. Please note that they can be resource-intensive as well, so please use SSMS carefully. SQL SERVER – Generate Report for Index Physical Statistics – SSMS SQL SERVER – Out of the Box – Activity and Performance Reports from SSSMS SQL SERVER – Configure Management Data Collection in Quick Steps – T-SQL Tuesday #005 Junior developers and DBA can use these reports right away and can also start learning and exploring most database performance issues with the help of Sr. DBAs. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, SQL, SQL Authority, SQL Performance, SQL Query, SQL Server, SQL Server Management Studio, SQL Tips and Tricks, T SQL, Technology Tagged: SQL Reporting, SQL Reports

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  • SQL SERVER – Installing AdventureWorks for SQL Server 2011

    - by pinaldave
    I just began with SQL Server 2011 Denali CTP1. The very first thing, I realized that there is no AdventureWorks Sample Database available for Denali. I quickly searched online and reached to Microsoft documentations where it provides information of the how to install (restore) AdventureWorks for SQL Server 2011 for Denali. Download the AdventureWorks from here. Run following script (replace your path of mdf file. CREATE DATABASE AdventureWorks2008R2 ON (FILENAME = 'C:\SQL 11 CTP1\CTP1\AdventureWorks2008R2_Data.mdf') FOR ATTACH_REBUILD_LOG ; When you run above script it will give you following message and you are DONE! File activation failure. The physical file name "C:\Program Files\Microsoft SQL Server\MSSQL11.MSSQLSERVER\MSSQL\DATA\AdventureWorks2008R2_Log.ldf" may be incorrect. New log file 'C:\SQL 11 CTP1\CTP1\AdventureWorks2008R2_log.ldf' was created. Converting database 'AdventureWorks2008R2' from version 679 to the current version 684. Database 'AdventureWorks2008R2' running the upgrade step from version 679 to version 680. Database 'AdventureWorks2008R2' running the upgrade step from version 680 to version 681. Database 'AdventureWorks2008R2' running the upgrade step from version 681 to version 682. Database 'AdventureWorks2008R2' running the upgrade step from version 682 to version 683. Database 'AdventureWorks2008R2' running the upgrade step from version 683 to version 684. I will soon write my experience about Denali. However, SQL Server Management Studio more started to look a like Visual Studio. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: Pinal Dave, SQL, SQL Authority, SQL Backup and Restore, SQL Query, SQL Scripts, SQL Server, SQL Server Management Studio, SQL Tips and Tricks, T SQL, Technology

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  • SQLAuthority News – Statistics Used by the Query Optimizer in Microsoft SQL Server 2008 – Microsoft Whitepaper

    - by pinaldave
    I recently presented session on Statistics and Best Practices in Virtual Tech Days on Nov 22, 2010. The sessions was very popular and I got many questions right after the sessions. The number question I had received was where everybody can get the further information. I am very much happy that my sessions created some curiosity for one of the most important feature of the SQL Server. Statistics are the heart of the SQL Server. Microsoft has published a white paper on the subject how statistics are useful to Query Optimizer. Here is the abstract of the same white paper from Microsoft. Statistics Used by the Query Optimizer in Microsoft SQL Server 2008 Writer: Eric N. Hanson and Yavor Angelov Microsoft SQL Server 2008 collects statistical information about indexes and column data stored in the database. These statistics are used by the SQL Server query optimizer to choose the most efficient plan for retrieving or updating data. This paper describes what data is collected, where it is stored, and which commands create, update, and delete statistics. By default, SQL Server 2008 also creates and updates statistics automatically, when such an operation is considered to be useful. This paper also outlines how these defaults can be changed on different levels (column, table, and database). In addition, it presents how certain query language features, such as Transact-SQL variables, interact with use of statistics by the optimizer, and it provides guidance for using these features when writing queries so you can obtain good query performance. Link to white paper Statistics Used by the Query Optimizer in Microsoft SQL Server 2008 ?Reference: Pinal Dave (http://blog.SQLAuthority.com)   Filed under: Pinal Dave, SQL, SQL Authority, SQL Documentation, SQL Download, SQL Query, SQL Scripts, SQL Server, SQL Tips and Tricks, SQL White Papers, SQLAuthority News, T SQL, Technology

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  • SQL SERVER – Find Max Worker Count using DMV – 32 Bit and 64 Bit

    - by pinaldave
    During several recent training courses, I found it very interesting that Worker Thread is not quite known to everyone despite the fact that it is a very important feature. At some point in the discussion, one of the attendees mentioned that we can double the Worker Thread if we double the CPU (add the same number of CPU that we have on current system). The same discussion has triggered this quick article. Here is the DMV which can be used to find out Max Worker Count SELECT max_workers_count FROM sys.dm_os_sys_info Let us run the above query on my system and find the results. As my system is 32 bit and I have two CPU, the Max Worker Count is displayed as 512. To address the previous discussion, adding more CPU does not necessarily double the Worker Count. In fact, the logic behind this simple principle is as follows: For x86 (32-bit) upto 4 logical processors  max worker threads = 256 For x86 (32-bit) more than 4 logical processors  max worker threads = 256 + ((# Procs – 4) * 8) For x64 (64-bit) upto 4 logical processors  max worker threads = 512 For x64 (64-bit) more than 4 logical processors  max worker threads = 512+ ((# Procs – 4) * 8) In addition to this, you can configure the Max Worker Thread by using SSMS. Go to Server Node >> Right Click and Select Property >> Select Process and modify setting under Worker Threads. According to Book On Line, the default Worker Thread settings are appropriate for most of the systems. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, SQL, SQL Authority, SQL Query, SQL Scripts, SQL Server, SQL System Table, SQL Tips and Tricks, T SQL, Technology Tagged: SQL DMV

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  • SQL SERVER – Color Coding SQL Server Management Studio Status Bar – SQL in Sixty Seconds #023 – Video

    - by pinaldave
    I often see developers executing the unplanned code on production server when they actually want to execute on the development server. Developers and DBAs get confused because when they use SQL Server Management Studio (SSMS) they forget to pay attention to the server they are connecting. It is very easy to fix this problem. You can select different color for a different server. Once you have different color for different server in the status bar, it will be easier for developer easily notice the server against which they are about to execute the script. Personally when I work on SQL Server development, here is the color code, which I follow. I keep Green for my development server, blue for my staging server and red for my production server. Honestly color coding does not signify much but different color for different server is the key here. More Tips on SSMS in SQL in Sixty Seconds: Generate Script for Schema and Data in SQL Server – SQL in Sixty Seconds #021  Remove Debug Button in SQL Server Management Studio – SQL in Sixty Seconds #020  Three Tricks to Comment T-SQL in SQL Server Management Studio – SQL in Sixty Seconds #019  Importing CSV into SQL Server – SQL in Sixty Seconds #018   Tricks to Replace SELECT * with Column Names – SQL in Sixty Seconds #017 I encourage you to submit your ideas for SQL in Sixty Seconds. We will try to accommodate as many as we can. If we like your idea we promise to share with you educational material. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: Database, Pinal Dave, PostADay, SQL, SQL Authority, SQL in Sixty Seconds, SQL Query, SQL Scripts, SQL Server, SQL Server Management Studio, SQL Tips and Tricks, T SQL, Technology, Video

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  • SQL SERVER – What is AdventureWorks?

    - by pinaldave
    NOTE: If you know the answer of this question, then I request you to stop reading this post right now. Please do not leave comment about this blog post not being useful to you, if you knew the answer. Few days ago, I received DM asking What is an AdventureWorks database and why in all the examples I use that instead of any other database (e.g. Pubs or  Northwind)? As matter of fact, when I went back to my question list, which I have yet not answered, there were a few more variations of this same question. AdventureWorks is a Sample Database shipped with SQL Server and it can be downloaded from http://codeplex.com site. AdventureWorks has replaced Northwind and Pubs from the sample database in SQL Server 2005. The Microsoft team keeps updating the sample database as they release new versions. Here are some quick links: AdventureWorks SQL Server 2008 SR4 AdventureWorks 2008R2 November CTP AdventureWorks for SQL Azure (December CTP) AventureWorks for SQL Server 2005 SP2A SQL SERVER – 2008 – Download and Install Samples Database AdventureWorks 2005 – Detail Tutorial I have previously written few other articles on the same subject; you can find them easily here: [email protected] Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, SQL, SQL Authority, SQL Documentation, SQL Download, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology

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  • SQLAuthority News – SQL Server Cheat Sheet from MidnightDBA

    - by pinaldave
    When I read the article from MidnightDBA (I should say MidnightDBAs because it is about Jen and Sean) regarding T-SQL for the Absentminded DBA, my natural reaction was that it is a perfect extension. A year ago around the same month, I had created SQL Server Cheatsheet. I have distributed a lot of copies of it since I produced it. In fact, while attending TechMela in Nepal today, I am getting many requests to get copies of SQL Server Cheatsheet. When I checked my RSS feed, I realized that Jen and Sean have a perfect cheat sheet for intermediate level developers. I would like to suggest to all of you to read their post and download the Absentminded DBA’s Cheat Sheet for IntermediateTSQL. It is available in two formats: PDF and Docx. I just love how the members of the community help each other grow. I am fortunate that I have received excellent feedback/corrections and criticism on my blog posts for so many times. Criticism and corrections, after all, are absolutely needed and make a better community as a whole. Reference : Pinal Dave (http://blog.SQLAuthority.com) Filed under: MVP, Pinal Dave, SQL, SQL Authority, SQL Download, SQL Query, SQL Scripts, SQL Server, SQL Tips and Tricks, SQLAuthority News, T SQL, Technology Tagged: SQL Cheat Sheet

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