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• SQL SERVER – Reduce the Virtual Log Files (VLFs) from LDF file

  - by pinaldave

  Earlier, I wrote a quite note on SQL SERVER – Detect Virtual Log Files (VLF) in LDF. Because of this I got responses suggesting too many VLFs are bad for log file. This prompts to a simple question: “How many is ‘too many’ VLFs?” I suggest that you go and read an article written by Kimberly over here. I am sure that you are going to have a clear understanding of what a good number for your VLFs is from that article. If you have lots of VLFs, you can reduce them right away using the following method: (I am just attempting to write a working script over here.) USE AdventureWorks GO BACKUP LOG AdventureWorks TO DISK='d:\adtlog.bak' GO -- Get Logical file name of the log file sp_helpfile GO DBCC SHRINKFILE(AdventureWorks_Log,TRUNCATEONLY) GO ALTER DATABASE AdventureWorks MODIFY FILE (NAME = AdventureWorks_Log,SIZE = 1GB) GO DBCC LOGINFO GO Again, here I have assumed that your initial log size is 1 GB, but in reality you should select the number based on your own ideal size of the log file. If your log file grows to 10 GB every day, you may want to put the value as 10 GB. For accuracy, read what Kimberly’s original article says over here. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, PostADay, SQL, SQL Authority, SQL Query, SQL Scripts, SQL Server, SQL Tips and Tricks, T SQL, Technology

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• SQL SERVER – What is Fill Factor and What is the Best Value for Fill Factor

  - by pinaldave

  Working in performance tuning area, one has to know about Index and Index Maintenance. For any Index the most important property is Fill Factor. Fill factor is the value that determines the percentage of space on each leaf-level page to be filled with data. In an SQL Server, the smallest unit is a page, which is made of  Page with size 8K. Every page can store one or more rows based on the size of the row. The default value of the Fill Factor is 100, which is same as value 0. The default Fill Factor (100 or 0) will allow the SQL Server to fill the leaf-level pages of an index with the maximum numbers of the rows it can fit. There will be no or very little empty space left in the page, when the fill factor is 100. I have written following two article about Fill Factor. What is Fill factor? – Index, Fill Factor and Performance – Part 1 What is the best value for the Fill Factor? – Index, Fill Factor and Performance – Part 2 I strongly encourage read them and provide your feedback. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, PostADay, SQL, SQL Authority, SQL Index, SQL Performance, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology

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• SQL SERVER – Effect of Collation on Resultset – SQL in Sixty Seconds #026 – Video

  - by pinaldave

  Collation is a very important concept but often ignored. I have often seen developers either not understanding this or ignored it – this is plain wrong. In simple word we can say Collation is the language or interpreting done by SQL Server. Well, in today’s SQL in Sixty Seconds we are going to observe how collation affects the resultset. Today’s blog post is inspired from my earlier blog post SQL SERVER – Effect of Case Sensitive Collation on Resultset. I strongly encourage you to read this earlier blog post for sample code as well additional explanation related to the concept shared in today’s SQL in Sixty Seconds. Here is the code used in the video. USE TempDB GO -- Sample Data Building CREATE TABLE ColTable (Col1 VARCHAR(15) COLLATE Latin1_General_CI_AS, Col2 VARCHAR(14) COLLATE Latin1_General_CS_AS) ; INSERT ColTable(Col1, Col2) VALUES ('Apple','Apple'), ('apple','apple'), ('pineapple','pineapple'), ('Pineapple','Pineapple'); GO -- Retrieve Data SELECT * FROM ColTable GO -- Retrieve Data SELECT * FROM ColTable ORDER BY Col1 GO -- Retrieve Data SELECT * FROM ColTable ORDER BY Col2 GO -- Clean up DROP TABLE ColTable GO Related Tips in SQL in Sixty Seconds: SQL SERVER – Effect of Case Sensitive Collation on Resultset Example of Width Sensitive and Width Insensitive Collation Collation and Collation Sensitivity – Quiz – Puzzle – 6 of 31 Change Collation of Database Column – T-SQL Script Find Collation of Database and Table Column Using T-SQL Default Collation of SQL Server 2008 Cannot resolve collation conflict for equal to operation 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 – Question to You – When to use Function and When to use Stored Procedure

  - by pinaldave

  This week has been very interesting week. I have asked few questions to users and have received remarkable participation on the subject. Q1) SQL SERVER – Puzzle – SELECT * vs SELECT COUNT(*) Q2) SQL SERVER – Puzzle – Statistics are not Updated but are Created Once Keeping the same spirit up, I am asking the third question over here. Q3) When to use User Defined Function and when to use Stored Procedure in your development? Personally, I believe that they are both different things - they cannot be compared. I can say, it will be like comparing apples and oranges. Each has its own unique use. However, they can be used interchangeably at many times and in real life (i.e., production environment). I have personally seen both of these being used interchangeably many times. This is the precise reason for asking this question. When do you use Function and when do you use Stored Procedure? What are Pros and Cons of each of them when used instead of each other? If you are going to answer that ‘To avoid repeating code, you use Function’ - please think harder! Stored procedure can do the same. In SQL Server Denali, even the stored procedure can return the result just like Function in SELECT statement; so if you are going to answer with ‘Function can be used in SELECT, whereas Stored Procedure cannot be used’ - again think harder! (link). Now, what do you say? I will post the answers of all the three questions with due credit next week. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, PostADay, Readers Question, SQL, SQL Authority, SQL Function, SQL Puzzle, SQL Query, SQL Server, SQL Stored Procedure, SQL Tips and Tricks, SQLServer, T SQL, Technology

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• SQL SERVER – Introduction to PERCENTILE_CONT() – Analytic Functions Introduced in SQL Server 2012

  - by pinaldave

  SQL Server 2012 introduces new analytical function PERCENTILE_CONT(). The book online gives following definition of this function: Computes a specific percentile for sorted values in an entire rowset or within distinct partitions of a rowset in Microsoft SQL Server 2012 Release Candidate 0 (RC 0). For a given percentile value P, PERCENTILE_DISC sorts the values of the expression in the ORDER BY clause and returns the value with the smallest CUME_DIST value (with respect to the same sort specification) that is greater than or equal to P. If you are clear with understanding of the function – no need to read further. If you got lost here is the same in simple words – it is lot like finding median with percentile value. Now let’s have fun following query: USE AdventureWorks GO SELECT SalesOrderID, OrderQty, ProductID, PERCENTILE_CONT(0.5) WITHIN GROUP (ORDER BY ProductID) OVER (PARTITION BY SalesOrderID) AS MedianCont FROM Sales.SalesOrderDetail WHERE SalesOrderID IN (43670, 43669, 43667, 43663) ORDER BY SalesOrderID DESC GO The above query will give us the following result: You can see that I have used PERCENTILE_COUNT(0.5) in query, which is similar to finding median. Let me explain above diagram with little more explanation. The defination of median is as following: In case of Even Number of elements = In ordered list add the two digits from the middle and devide by 2 In case of Odd Numbers of elements = In ordered list select the digits from the middle I hope this example gives clear idea how PERCENTILE_CONT() works. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, PostADay, SQL, SQL Authority, SQL Function, SQL Query, SQL Scripts, SQL Server, SQL Tips and Tricks, T SQL, Technology

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• SQL SERVER – Function: Is Function – SQL in Sixty Seconds #004 – Video

  - by pinaldave

  Today is February 29th. An unique date which we only get to observe once every four year. Year 2012 is leap year and SQL Server 2012 is also releasing this year. Yesterday I wrote an article where we have seen observed how using four different function we can create another function which can accurately validate if any year is leap year or not. We will use three functions newly introduced in SQL Server 2012 and demonstrate how we can find if any year is leap year or not. This function uses three of the SQL Server 2012 functions - IIF, EOMONTH and CONCAT. When I wrote this function, this is the sortest function I ever wrote to find out leap year. Please watch the video and let me know if any shorter function can be written to find leap year. More on Leap Yer: Detecting Leap Year in T-SQL using SQL Server 2012 – IIF, EOMONTH and CONCAT Function Date and Time Functions – EOMONTH() – A Quick Introduction Script/Function to Find Last Day of Month  I encourage you to submit your ideas for SQL in Sixty Seconds. We will try to accommodate as many as we can. 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 Tips and Tricks, SQLServer, T SQL, Video

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• SQL SERVER – Where Can YOU Get My Books – SQL Server Interview Question and Answers

  - by pinaldave

  Earlier month I released by third book SQL Server Interview Question and Answers. The focus of this book is ‘master the basics’. If you rate yourself 10 out of 10 in SQL Server – this book is not for you but if you want to learn fundamentals or want to refresh your fundamentals this book is for YOU. Earlier I was overwhelmed by love you all have shown to this book on release date leading our three digit inventory to run out of stock. Read detail blog post about the subject over here A Real Story of Book Getting ‘Out of Stock’ to A 25% Discount Story Available. Well, we learn the lesson from the experience and have made sure that the inventory does not run out any more. Since then we are now available on multiple outlets. Pretty much anywhere in USA and India the book is available. Additionally, where ever Amazon ships internationally. I have created dedicated page where I have listed where one can avail this book from Details of SQL Server Interview Question and Answers. Even though I keep on getting common question like – where one can get this book. You can get this book from: USA: Amazon India: Flipkart | IndiaPlaza | Crossword In India now you can walk into any crossword store and ask this book, if they do not have it, you can ask them get one for you. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Best Practices, Pinal Dave, PostADay, SQL, SQL Authority, SQL Documentation, SQL Download, SQL Interview Questions and Answers, SQL Query, SQL Server, SQL Tips and Tricks, SQLAuthority Author Visit, SQLAuthority Book Review, SQLAuthority News, T SQL, Technology

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• SQL SERVER – Copy Statistics from One Server to Another Server

  - by pinaldave

  I was recently working on a performance tuning project in Dubai (yeah I was able to see the tallest tower from the window of my work place). I had a very interesting learning experience there. There was a situation where we wanted to receive the schema of original database from a certain client. However, the client was not able to provide us any data due to privacy issues. The schema was very important because without having an access to underlying data, it was a bit difficult to judge the queries etc. For example, without any primary data, all the queries are running in 0 (zero) milliseconds and all were using nested loop as there were no data to be returned. Even though we had CPU offending queries, they were not doing anything without the data in the tables. This was really a challenge as I did not have access to production server data and I could not recreate the scenarios as production without data. Well, I was confused but Ruben from Solid Quality Mentors, Spain taught me new tricks. He suggested that when table schema is generated, we can create the statistics consequently. Here is how we had done that: Once statistics is created along with the schema, without data in the table, all the queries will work as how they will work on production server. This way, without access to the data, we were able to recreate the same scenario as production server on development server. When observed at the script, you will find that the statistics were also generated along with the query. You will find statistics included in WITH STATS_STREAM clause. What a very simple and effective script. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, PostADay, SQL, SQL Authority, SQL Query, SQL Scripts, SQL Server, SQL Tips and Tricks, SQLServer, T SQL, Technology Tagged: SQL Statistics, Statistics

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• SQL SERVER- Differences Between Left Join and Left Outer Join

  - by pinaldave

  There are a few questions that I had decided not to discuss on this blog because I think they are very simple and many of us know it. Many times, I even receive not-so positive notes from several readers when I am writing something simple. However, assuming that we know all and beginners should know everything is not the right attitude. Since day 1, I have been keeping a small journal regarding questions that I receive in this blog. There are around 200+ questions I receive every day through emails, comments and occasional phone calls. Yesterday, I received a comment with the following question: What are the differences between Left Join and Left Outer Join? Click here to read original comment. This question has triggered the threshold of receiving the same question repeatedly. Here is the answer: There is absolutely no difference between LEFT JOIN and LEFT OUTER JOIN. The same is true for RIGHT JOIN and RIGHT OUTER JOIN. When you use LEFT JOIN keyword in SQL Server, it means LEFT OUTER JOIN only. I have already written in-depth visual diagram discussing the JOINs. I encourage all of you to read the article for further understanding of the JOINs: Read Introduction to JOINs – Basic of JOINs Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, PostADay, SQL, SQL Authority, SQL Joins, SQL Query, SQL Scripts, SQL Server, SQL Tips and Tricks, T SQL, Technology

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• SQL SERVER – Plan Cache and Data Cache in Memory

  - by pinaldave

  I get following question almost all the time when I go for consultations or training. I often end up providing the scripts to my clients and attendees. Instead of writing new blog post, today in this single blog post, I am going to cover both the script and going to link to original blog posts where I have mentioned about this blog post. Plan Cache in Memory USE AdventureWorks GO SELECT [text], cp.size_in_bytes, plan_handle FROM sys.dm_exec_cached_plans AS cp CROSS APPLY sys.dm_exec_sql_text(plan_handle) WHERE cp.cacheobjtype = N'Compiled Plan' ORDER BY cp.size_in_bytes DESC GO Further explanation of this script is over here: SQL SERVER – Plan Cache – Retrieve and Remove – A Simple Script Data Cache in Memory USE AdventureWorks GO SELECT COUNT(*) AS cached_pages_count, name AS BaseTableName, IndexName, IndexTypeDesc FROM sys.dm_os_buffer_descriptors AS bd INNER JOIN ( SELECT s_obj.name, s_obj.index_id, s_obj.allocation_unit_id, s_obj.OBJECT_ID, i.name IndexName, i.type_desc IndexTypeDesc FROM ( SELECT OBJECT_NAME(OBJECT_ID) AS name, index_id ,allocation_unit_id, OBJECT_ID FROM sys.allocation_units AS au INNER JOIN sys.partitions AS p ON au.container_id = p.hobt_id AND (au.TYPE = 1 OR au.TYPE = 3) UNION ALL SELECT OBJECT_NAME(OBJECT_ID) AS name, index_id, allocation_unit_id, OBJECT_ID FROM sys.allocation_units AS au INNER JOIN sys.partitions AS p ON au.container_id = p.partition_id AND au.TYPE = 2 ) AS s_obj LEFT JOIN sys.indexes i ON i.index_id = s_obj.index_id AND i.OBJECT_ID = s_obj.OBJECT_ID ) AS obj ON bd.allocation_unit_id = obj.allocation_unit_id WHERE database_id = DB_ID() GROUP BY name, index_id, IndexName, IndexTypeDesc ORDER BY cached_pages_count DESC; GO Further explanation of this script is over here: SQL SERVER – Get Query Plan Along with Query Text and Execution Count Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, SQL, SQL Authority, SQL Optimization, SQL Performance, SQL Query, SQL Scripts, SQL Server, SQL Tips and Tricks, T SQL Tagged: SQL Memory

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• SQL SERVER – 2012 – Summary of All the Analytic Functions – MSDN and SQLAuthority

  - by pinaldave

  SQL Server 2012 (RC0 Available here) has introduced new analytic functions. These functions were long awaited and I am glad that they are here. Previously when any of this function was needed people use to write long T-SQL code to simulate that and now no need of the same. Having available native function also helps performance as well readability. In last few days I have written many articles on this subject on my blog. The goal was make these complex analytic functions easy to understand and make it widely accepted. As this new functions are available and as awareness spreads we should start using the new functions. Here is the quick list of the new function and relevant MSDN site. Function SQLAuthority MSDN CUME_DIST CUME_DIST CUME_DIST FIRST_VALUE FIRST_VALUE FIRST_VALUE LAST_VALUE LAST_VALUE LAST_VALUE LEAD LEAD LEAD LAG LAG LAG PERCENTILE_CONT PERCENTILE_CONT PERCENTILE_CONT PERCENTILE_DISC PERCENTILE_DISC PERCENTILE_DISC PERCENT_RANK PERCENT_RANK PERCENT_RANK I also enjoyed three different puzzles during the course of this series which gave clear idea to the SQL Server 2012 analytic functions. SQL SERVER – Puzzle to Win Print Book – Functions FIRST_VALUE and LAST_VALUE with OVER clause and ORDER BY SQL SERVER – Puzzle to Win Print Book – Write T-SQL Self Join Without Using LEAD and LAG SQL SERVER – Puzzle to Win Print Book – Explain Value of PERCENTILE_CONT() Using Simple Example This series will be always my dear series as during this series I had went through very unique experience of my book going out of stock and becoming available after 48 hours. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, PostADay, SQL, SQL Authority, SQL Function, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology

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• SQL SERVER – Demo Script – Keeping CPU Busy

  - by pinaldave

  Recently face very interesting situation, during presentations at event, I was asked very famous questions: “My CPU is very high all the time, how can I reduce it?” This is very interesting question and there are many answers and a single blog post is not good enough to justify this subject. I presented few situation to the person who asked the question. The member of the audience who asked question came to me afterwords and asked me few detailed questions. To answer him, I quickly wrote query which simulate high CPU. Here is the script which I wrote which increased CPU from 10% to 80%. I was wondering if there is any similar script which can simulate high CPU usage. If you have share with me and I will publish with due credit. Here is my script for the same: USE AdventureWorks GO DECLARE @Flag INT SET @Flag = 1 WHILE(@Flag < 1000) BEGIN ALTER INDEX [PK_SalesOrderDetail_SalesOrderID_SalesOrderDetailID] ON [Sales].[SalesOrderDetail] REBUILD SET @Flag = @Flag + 1 END GO   Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, PostADay, SQL, SQL Authority, SQL Query, SQL Scripts, SQL Server, SQL Tips and Tricks, T SQL, Technology

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• SQL SERVER – Installing AdventureWorks Sample Database – SQL in Sixty Seconds #010 – Video

  - by pinaldave

  SQL Server has so many enhancements and features that quite often I feel like playing with various features and try out new things. I often come across situation where I want to try something new but I do not have sample data to experiment with. Also just like any sane developer I do not try any of my new experiments on production server. Additionally, when it is about new version of the SQL Server, there are cases when there is no relevant sample data even available on development server. In this kind of scenario sample database can be very much handy. Additionally, in many SQL Books and online blogs and articles there are scripts written by using AdventureWork database. The often receive request that where people can get sample database as well how to restore sample database. In this sixty seconds video we have discussed the same. You can get various resources used in this video from http://bit.ly/adw2012. More on Errors: SQL SERVER – Install Samples Database Adventure Works for SQL Server 2012 SQL SERVER – 2012 – All Download Links in Single Page – SQL Server 2012 SQLAuthority News – SQL Server 2012 – Microsoft Learning Training and Certification SQLAuthority News – Download Microsoft SQL Server 2012 RTM Now 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 Tips and Tricks, T SQL, Technology, Video

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• SQL SERVER – 2011 – SEQUENCE is not IDENTITY

  - by pinaldave

  Yesterday I posted blog post on the subject SQL SERVER – 2011 – Introduction to SEQUENCE – Simple Example of SEQUENCE and I received comment where user was not clear about difference between SEQUENCE and IDENTITY. The reality is that SEQUENCE not like IDENTITY. There is very clear difference between them. Identity is about single column. Sequence is always incrementing and it is not dependent on any table. Here is the quick example of the same. USE AdventureWorks2008R2 GO CREATE SEQUENCE [Seq] AS [int] START WITH 1 INCREMENT BY 1 MAXVALUE 20000 GO -- Run five times SELECT NEXT VALUE FOR Seq AS SeqNumber; SELECT NEXT VALUE FOR Seq AS SeqNumber; SELECT NEXT VALUE FOR Seq AS SeqNumber; SELECT NEXT VALUE FOR Seq AS SeqNumber; SELECT NEXT VALUE FOR Seq AS SeqNumber; GO -- Clean Up DROP SEQUENCE [Seq] GO Here is the resultset. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, PostADay, SQL, SQL Authority, SQL Query, SQL Scripts, SQL Server, SQL Tips and Tricks, T SQL, Technology

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• SQL SERVER – Copy Column Headers from Resultset – SQL in Sixty Seconds #027 – Video

  - by pinaldave

  SQL Server Management Studio returns results in Grid View, Text View and to the file. When we copy results from Grid View to Excel there is a common complaint that the column  header displayed in resultset is not copied to the Excel. I often spend time in performance tuning databases and I run many DMV’s in SSMS to get a quick view of the server. In my case it is almost certain that I need all the time column headers when I copy my data to excel or any other place. SQL Server Management Studio have two different ways to do this. Method 1: Ad-hoc When result is rendered you can right click on the resultset and click on Copy Header. This will copy the headers along with the resultset. Additionally, you can use the shortcut key CTRL+SHIFT+C for coping column headers along with the resultset. Method 2: Option Setting at SSMS level This is SSMS level settings and I kept this option always selected as I often need the column headers when I select the resultset. Go Tools >> Options >> Query Results >> SQL Server >> Results to Grid >> Check the Box “Include column header when copying or saving the results.” Both of the methods are discussed in following SQL in Sixty Seconds Video. Here is the code used in the video. Related Tips in SQL in Sixty Seconds: Copy Column Headers in Query Analyzers in Result Set Getting Columns Headers without Result Data – SET FMTONLY ON 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 – Reducing Page Contention on TempDB

  - by pinaldave

  I have recently received following email. “We are using TraceFlag 1118 to reduce the tempDB contention on our servers (2000 and 2005). What is your opinion? We have read lots of material, would you please answer me in single line.” Wow, this was very interesting question. What intrigued me was the second last where I am asked to answer in a single line. There is something about this strong email, I feel like blogging it here. I think I can talk over this subject forever – well, there is no clear answer. There are so many caveats about everything.  Again, I must stay honest to the request about answering in single line. I also do not like to answer which is YES/NO. What should I do? Let me ask this question to community today? What will you answer to this email? Let me start this by answering it myself in one line and taking one side. “I enable this trace flag in SQL Server 2000 without hot patch or service pack and not in later versions (2005+) onwards as code is improved”. What do you do in this case? The best answer will feature in this blog with due credit. Regarding further read and hint here is Microsoft KB which I think is very helpful. In quick summary: (Read KB for accuracy) When any page is allocated first 8 pages are allocated in mixed extended. This trace flag allocates uniform extended at the time, reducing contention. You can enable this trace flag at startup. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, PostADay, SQL, SQL Authority, SQL Query, SQL Scripts, SQL Server, SQL Tips and Tricks, T SQL, Technology Tagged: SQL TempDB, TempDB

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• SQL SERVER – Find Details for Statistics of Whole Database – DMV – T-SQL Script

  - by pinaldave

  I was recently asked is there a single script which can provide all the necessary details about statistics for any database. This question made me write following script. I was initially planning to use sp_helpstats command but I remembered that this is marked to be deprecated in future. Again, using DMV is the right thing to do moving forward. I quickly wrote following script which gives a lot more information than sp_helpstats. USE AdventureWorks GO SELECT DISTINCT OBJECT_NAME(s.[object_id]) AS TableName, c.name AS ColumnName, s.name AS StatName, s.auto_created, s.user_created, s.no_recompute, s.[object_id], s.stats_id, sc.stats_column_id, sc.column_id, STATS_DATE(s.[object_id], s.stats_id) AS LastUpdated FROM sys.stats s JOIN sys.stats_columns sc ON sc.[object_id] = s.[object_id] AND sc.stats_id = s.stats_id JOIN sys.columns c ON c.[object_id] = sc.[object_id] AND c.column_id = sc.column_id JOIN sys.partitions par ON par.[object_id] = s.[object_id] JOIN sys.objects obj ON par.[object_id] = obj.[object_id] WHERE OBJECTPROPERTY(s.OBJECT_ID,'IsUserTable') = 1 AND (s.auto_created = 1 OR s.user_created = 1); If you have better script to retrieve information about statistics, please share here and I will publish it with due credit. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, PostADay, SQL, SQL Authority, SQL DMV, SQL Query, SQL Scripts, SQL Server, SQL Tips and Tricks, T SQL, Technology Tagged: SQL Statistics, Statistics

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• SQL SERVER – Get Date and Time From Current DateTime – SQL in Sixty Seconds #025 – Video

  - by pinaldave

  This is 25th video of series SQL in Sixty Seconds we started a few months ago. Even though this is 25th video it seems like we have just started this few days ago. The best part of this SQL in Sixty Seconds is that one can learn something new in less than sixty seconds. There are many concepts which are not new for many but just we all have 60 seconds to refresh our memories. In this video I have touched a very simple question which I receive very frequently on this blog. Q1) How to get current date time? Q2) How to get Only Date from datetime? Q3) How to get Only Time from datetime? I have created a sixty second video on this subject and hopefully this will help many beginners in the SQL Server field. This sixty second video describes the same. Here is a similar script which I have used in the video. SELECT GETDATE() GO -- SQL Server 2000/2005 SELECT CONVERT(VARCHAR(8),GETDATE(),108) AS HourMinuteSecond, CONVERT(VARCHAR(8),GETDATE(),101) AS DateOnly; GO -- SQL Server 2008 Onwards SELECT CONVERT(TIME,GETDATE()) AS HourMinuteSeconds; SELECT CONVERT(DATE,GETDATE()) AS DateOnly; GO Related Tips in SQL in Sixty Seconds: Retrieve Current Date Time in SQL Server CURRENT_TIMESTAMP, GETDATE(), {fn NOW()} Get Time in Hour:Minute Format from a Datetime – Get Date Part Only from Datetime Get Current System Date Time Get Date Time in Any Format – UDF – User Defined Functions Date and Time Functions – EOMONTH() – A Quick Introduction DATE and TIME in SQL Server 2008 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. Image Credit: Movie Gone in 60 Seconds 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 – 2000 – DBCC SQLPERF(waitstats) – Wait Type – Day 24 of 28

  - by pinaldave

  I have received many comments, email, suggestions and motivations for my current series of wait types and wait statistics. One of the questions which I keep on receiving almost every other day is whether all of the discussions I have presented so far are also applicable to SQL Server 2000. Additionally, I receive another question asking me if wait statistics matters in SQL Server 2000. If it is, then the asker wants to know how to measure wait types for SQL Server 2000. In SQL Server, you can run the following command to get a list of all the wait types: DBCC SQLPERF(waitstats) The query above will work in SQL Server 2005/2008/R2  because of backup compatibility. As you might have noticed, I have been discussing everything keeping SQL Server 2005+ in mind, but I have given little consideration on SQL Server 2000. However, I am pretty sure that most of the suggestions I have provided are applicable to SQL Server 2000. The wait types I have been discussing mostly exist in SQL Server 2000 as well. But the difference of the 2000 version is that it gets late recent releases, but it is worth it. Wait types are very essential to measure performance bottleneck. Because of this, I do not have to state that I am big fan of them just so I could identify performance bottleneck. Please 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 Scripts, SQL Server, SQL Tips and Tricks, SQL Wait Stats, SQL Wait Types, T SQL, Technology

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• SQL SERVER – Identify Most Resource Intensive Queries – SQL in Sixty Seconds #029 – Video

  - by pinaldave

  There are a few questions I often get asked. I wonder how interesting is that in our daily life all of us have to often need the same kind of information at the same time. Here is the example of the similar questions: How many user created tables are there in the database? How many non clustered indexes each of the tables in the database have? Is table Heap or has clustered index on it? How many rows each of the tables is contained in the database? I finally wrote down a very quick script (in less than sixty seconds when I originally wrote it) which can answer above questions. I also created a very quick video to explain the results and how to execute the script. Here is the complete script which I have used in the SQL in Sixty Seconds Video. SELECT [schema_name] = s.name, table_name = o.name, MAX(i1.type_desc) ClusteredIndexorHeap, COUNT(i.TYPE) NoOfNonClusteredIndex, p.rows FROM sys.indexes i INNER JOIN sys.objects o ON i.[object_id] = o.[object_id] INNER JOIN sys.schemas s ON o.[schema_id] = s.[schema_id] LEFT JOIN sys.partitions p ON p.OBJECT_ID = o.OBJECT_ID AND p.index_id IN (0,1) LEFT JOIN sys.indexes i1 ON i.OBJECT_ID = i1.OBJECT_ID AND i1.TYPE IN (0,1) WHERE o.TYPE IN ('U') AND i.TYPE = 2 GROUP BY s.name, o.name, p.rows ORDER BY schema_name, table_name Related Tips in SQL in Sixty Seconds: Find Row Count in Table – Find Largest Table in Database Find Row Count in Table – Find Largest Table in Database – T-SQL Identify Numbers of Non Clustered Index on Tables for Entire Database Index Levels, Page Count, Record Count and DMV – sys.dm_db_index_physical_stats Index Levels and Delete Operations – Page Level Observation 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 – Capturing Wait Types and Wait Stats Information at Interval – Wait Type – Day 5 of 28

  - by pinaldave

  Earlier, I have tried to cover some important points about wait stats in detail. Here are some points that we had covered earlier. DMV related to wait stats reset when we reset SQL Server services DMV related to wait stats reset when we manually reset the wait types However, at times, there is a need of making this data persistent so that we can take a look at them later on. Sometimes, performance tuning experts do some modifications to the server and try to measure the wait stats at that point of time and after some duration. I use the following method to measure the wait stats over the time. -- Create Table CREATE TABLE [MyWaitStatTable]( [wait_type] [nvarchar](60) NOT NULL, [waiting_tasks_count] [bigint] NOT NULL, [wait_time_ms] [bigint] NOT NULL, [max_wait_time_ms] [bigint] NOT NULL, [signal_wait_time_ms] [bigint] NOT NULL, [CurrentDateTime] DATETIME NOT NULL, [Flag] INT ) GO -- Populate Table at Time 1 INSERT INTO MyWaitStatTable ([wait_type],[waiting_tasks_count],[wait_time_ms],[max_wait_time_ms],[signal_wait_time_ms], [CurrentDateTime],[Flag]) SELECT [wait_type],[waiting_tasks_count],[wait_time_ms],[max_wait_time_ms],[signal_wait_time_ms], GETDATE(), 1 FROM sys.dm_os_wait_stats GO ----- Desired Delay (for one hour) WAITFOR DELAY '01:00:00' -- Populate Table at Time 2 INSERT INTO MyWaitStatTable ([wait_type],[waiting_tasks_count],[wait_time_ms],[max_wait_time_ms],[signal_wait_time_ms], [CurrentDateTime],[Flag]) SELECT [wait_type],[waiting_tasks_count],[wait_time_ms],[max_wait_time_ms],[signal_wait_time_ms], GETDATE(), 2 FROM sys.dm_os_wait_stats GO -- Check the difference between Time 1 and Time 2 SELECT T1.wait_type, T1.wait_time_ms Original_WaitTime, T2.wait_time_ms LaterWaitTime, (T2.wait_time_ms - T1.wait_time_ms) DiffenceWaitTime FROM MyWaitStatTable T1 INNER JOIN MyWaitStatTable T2 ON T1.wait_type = T2.wait_type WHERE T2.wait_time_ms > T1.wait_time_ms AND T1.Flag = 1 AND T2.Flag = 2 ORDER BY DiffenceWaitTime DESC GO -- Clean up DROP TABLE MyWaitStatTable GO If you notice the script, I have used an additional column called flag. I use it to find out when I have captured the wait stats and then use it in my SELECT query to SELECT wait stats related to that time group. Many times, I select more than 5 or 6 different set of wait stats and I find this method very convenient to find the difference between wait stats. In a future blog post, we will talk about specific wait stats. Read all the post in the Wait Types and Queue series. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, PostADay, SQL, SQL Authority, SQL DMV, SQL Query, SQL Scripts, SQL Server, SQL Tips and Tricks, SQL Wait Stats, SQL Wait Types, T SQL, Technology

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• SQL SERVER – Get File Statistics Using fn_virtualfilestats

  - by pinaldave

  Quite often when I am staring at my SSMS I wonder what is going on under the hood in my SQL Server. I often want to know which database is very busy and which database is bit slow because of IO issue. Sometime, I think at the file level as well. I want to know which MDF or NDF is busiest and doing most of the work. Following query gets the same results very quickly. SELECT DB_NAME(vfs.DbId) DatabaseName, mf.name, mf.physical_name, vfs.BytesRead, vfs.BytesWritten, vfs.IoStallMS, vfs.IoStallReadMS, vfs.IoStallWriteMS, vfs.NumberReads, vfs.NumberWrites, (Size*8)/1024 Size_MB FROM ::fn_virtualfilestats(NULL,NULL) vfs INNER JOIN sys.master_files mf ON mf.database_id = vfs.DbId AND mf.FILE_ID = vfs.FileId GO When you run above query you will get many valuable information like what is the size of the file as well how many times the reads and writes are done for each file. It also displays the read/write data in bytes. Due to IO if there has been any stall (delay) in read or write, you can know that as well. I keep this handy but have not shared on blog earlier. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, PostADay, SQL, SQL Authority, SQL Query, SQL Scripts, SQL Server, SQL Tips and Tricks, SQL View, T SQL, Technology Tagged: Statistics

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• SQL SERVER – Three Methods to Insert Multiple Rows into Single Table – SQL in Sixty Seconds #024 – Video

  - by pinaldave

  One of the biggest ask I have always received from developers is that if there is any way to insert multiple rows into a single table in a single statement. Currently when developers have to insert any value into the table they have to write multiple insert statements. First of all this is not only boring it is also very much time consuming as well. Additionally, one has to repeat the same syntax so many times that the word boring becomes an understatement. In the following quick video we have demonstrated three different methods to insert multiple values into a single table. -- Insert Multiple Values into SQL Server CREATE TABLE #SQLAuthority (ID INT, Value VARCHAR(100)); Method 1: Traditional Method of INSERT…VALUE -- Method 1 - Traditional Insert INSERT INTO #SQLAuthority (ID, Value) VALUES (1, 'First'); INSERT INTO #SQLAuthority (ID, Value) VALUES (2, 'Second'); INSERT INTO #SQLAuthority (ID, Value) VALUES (3, 'Third'); Clean up -- Clean up TRUNCATE TABLE #SQLAuthority; Method 2: INSERT…SELECT -- Method 2 - Select Union Insert INSERT INTO #SQLAuthority (ID, Value) SELECT 1, 'First' UNION ALL SELECT 2, 'Second' UNION ALL SELECT 3, 'Third'; Clean up -- Clean up TRUNCATE TABLE #SQLAuthority; Method 3: SQL Server 2008+ Row Construction -- Method 3 - SQL Server 2008+ Row Construction INSERT INTO #SQLAuthority (ID, Value) VALUES (1, 'First'), (2, 'Second'), (3, 'Third'); Clean up -- Clean up DROP TABLE #SQLAuthority; Related Tips in SQL in Sixty Seconds: SQL SERVER – Insert Multiple Records Using One Insert Statement – Use of UNION ALL SQL SERVER – 2008 – Insert Multiple Records Using One Insert Statement – Use of Row Constructor 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 – SQL Server Performance: Indexing Basics – SQL in Sixty Seconds #006 – Video

  - by pinaldave

  A DBA’s role is critical, because a production environment has to run 24×7, hence maintenance, trouble shooting, and quick resolutions are the need of the hour.  The first baby step into any performance tuning exercise in SQL Server involves creating, analyzing, and maintaining indexes. Though we have learnt indexing concepts from our college days, indexing implementation inside SQL Server can vary.  Understanding this behavior and designing our applications appropriately will make sure the application is performed to its highest potential. Vinod Kumar and myself we often thought about this and realized that practical understanding of the indexes is very important. One can not master every single aspects of the index. However there are some minimum expertise one should gain if performance is one of the concern. More on Indexes: SQL Index SQL Performance I encourage you to submit your ideas for SQL in Sixty Seconds. We will try to accommodate as many as we can. Here is the interview of Vinod Kumar by myself. 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 Tips and Tricks, SQLServer, T SQL, Video

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• SQL SERVER – DATEDIFF – Accuracy of Various Dateparts

  - by pinaldave

  I recently received the following question through email and I found it very interesting so I want to share it with you. “Hi Pinal, In SQL statement below the time difference between two given dates is 3 sec, but when checked in terms of Min it says 1 Min (whereas the actual min is 0.05Min) SELECT DATEDIFF(MI,'2011-10-14 02:18:58' , '2011-10-14 02:19:01') AS MIN_DIFF Is this is a BUG in SQL Server ?” Answer is NO. It is not a bug; it is a feature that works like that. Let us understand that in a bit more detail. When you instruct SQL Server to find the time difference in minutes, it just looks at the minute section only and completely ignores hour, second, millisecond, etc. So in terms of difference in minutes, it is indeed 1. The following will also clear how DATEDIFF works: SELECT DATEDIFF(YEAR,'2011-12-31 23:59:59' , '2012-01-01 00:00:00') AS YEAR_DIFF The difference between the above dates is just 1 second, but in terms of year difference it shows 1. If you want to have accuracy in seconds, you need to use a different approach. In the first example, the accurate method is to find the number of seconds first and then divide it by 60 to convert it to minutes. SELECT DATEDIFF(second,'2011-10-14 02:18:58' , '2011-10-14 02:19:01')/60.0 AS MIN_DIFF Even though the concept is very simple it is always a good idea to refresh it. Please share your related experience with me through your comments. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, PostADay, SQL, SQL Authority, SQL DateTime, SQL Query, SQL Scripts, SQL Server, SQL Tips and Tricks, T SQL, Technology

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