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  • SQL SERVER – Download SQL Server Product Documentation

    - by pinaldave
    Today I just returned from Bangalore User Group Meeting. Attending User Group meeting is indeed fun and really great experience. The best part of the User Group is meeting like minded people and have a great conversation with them. During the meeting I was asked why one has to go online to access SQL Server Product Documentation. I can clearly see there can be many reasons for why one wants the documentation to be available offline. The reasons can be anything but not limited to Company Firewall No Internet (power failure, on road or disaster) Internet Bandwidth Limitatoin Company Proxy Issues … and much more… In this kind of situation one needs documentation which is offline and easily available in local computer. The Microsoft SQL Server 2012 setup installs only the Help Viewer and related components for managing Help settings. Setup does not directly install any documentation. All of the SQL Server documentation is available online. Well, Microsoft has recently released Production Documentation available for offline users as well. You just have to download the executable file and follow all the instructions. Please follow the link below for download of the file. There is detailed instruction on how to download and install the documentation offline. Product Documentation for Microsoft SQL Server 2012 Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: PostADay, SQL, SQL Authority, SQL Documentation, SQL Download, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology

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  • SQL SERVER – DVM sys.dm_os_sys_info Column Name Changed in SQL Server 2012

    - by pinaldave
    Have you ever faced situation where something does not work and when you try to go and fix it – you like fixing it and started to appreciate the breaking changes. Well, this is exactly I felt yesterday. Before I begin my story of yesterday I want to state it candidly that I do not encourage anybody to use * in the SELECT statement. One of the my DBA friend who always used my performance tuning script yesterday sent me email asking following question - “Every time I want to retrieve OS related information in SQL Server – I used DMV sys.dm_os_sys_info. I just upgraded my SQL Server edition from 2008 R2 to SQL Server 2012 RC0 and it suddenly stopped working. Well, this is not the production server so the issue is not big yet but eventually I need to resolve this error. Any suggestion?” The funny thing was original email was very long but it did not talk about what is the exact error beside the query is not working. I think this is the disadvantage of being too friendly on email sometime. Well, never the less, I quickly looked at the DMV on my SQL Server 2008 R2 and SQL Server 2012 RC0 version. To my surprise I found out that there were few columns which are renamed in SQL Server 2012 RC0. Usually when people see breaking changes they do not like it but when I see these changes I was happy as new names were meaningful and additionally their new conversion is much more practical and useful. Here are the columns previous names - Previous Column Name New Column Name physical_memory_in_bytes physical_memory_kb bpool_commit_target committed_target_kb bpool_visible visible_target_kb virtual_memory_in_bytes virtual_memory_kb bpool_commited committed_kb If you read it carefully you will notice that new columns now display few results in the KB whereas earlier result was in bytes. When I see the results in bytes I always get confused as I could not guess what exactly it will convert to. I like to see results in kb and I am glad that new columns are now displaying the results in the kb. I sent the details of the new columns to my friend and ask him to check the columns used in application. From my comment he quickly realized why he was facing error and fixed it immediately. Overall – all was well at the end and I learned something new. 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

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  • SQL SERVER – What is Spatial Database? – Developing with SQL Server Spatial and Deep Dive into Spati

    - by pinaldave
    What is Spatial Database? A spatial database is a database that is optimized to store and query data related to objects in space, including points, lines and polygons. While typical databases can understand various numeric and character types of data, additional functionality needs to be added for databases to process spatial data types. (Source: Wikipedia) Today I will be talking about the same subject at Microsoft TechEd India. If you want to learn about how to spatial aspect of data and how to integrate them with SQL Server this is the perfect session for you. Spatial is very special concept of SQL Server and I really like how it is implemented in SQL Server. In general Performance Tuning and Query Optimization is something I always have enjoyed in my professional life. Index are my best friends and many time, by implementing and many time by removing I have improved the performance of the system. In this session, I will be talking about Index along with Spatial Data. As Spatial Database is very interesting concept, I will cover super short but very interesting 10 quick slides about this subject. I will make sure in very first 20 mins, you will understand following topics Introduction to Spatial Database One line definition Understanding Spatial Indexing Index Internals Query/Performance Tuning Query Hinting/Cost Analysis Spatial Index Catalog Views Performance Troubleshooting Finding Optimal Index using Spatial Index SP Common Errors Index Maintenance This slides decks will be followed by around 30 mins demo which will have story of geometry, geography, index internals and performance tuning. If you are interested in learning how GIS works and how SQL Server out of the box supports this wonderful tools, you will really like how the story is told. I am sure all people who attend the event will know how the Bangalore is positioned on the map of India. I will take example of Bangalore and Hyderabad and demonstrate how index can improve the performance. Well there are lots of story to tell in the session, and I will be opening this session with the beautiful script of Botticelli’s Birth of Venus created by Michael J. Swart. I will also demonstrate few real life scenario where I will be talking about Spatial Database and its usage. Do not miss this session. At the end of session there will be book awarded to best participant. My session details: Session 3: Developing with SQL Server Spatial and Deep Dive into Spatial Indexing Date: April 14, 2010 Time: 5:00pm-6:00pm Microsoft SQL Server 2008 delivers new spatial data types that enable you to consume, use, and extend location-based data through spatial-enabled applications. Attend this session to learn how to use spatial functionality in next version of SQL Server to build and optimize spatial queries. This session outlines the new geography data type to store geodetic spatial data and perform operations on it, use the new geometry data type to store planar spatial data and perform operations on it, take advantage of new spatial indexes for high performance queries, use the new spatial results tab to quickly and easily view spatial query results directly from within Management Studio, extend spatial data capabilities by building or integrating location-enabled applications through support for spatial standards and specifications and much more. 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 Tips and Tricks, SQLAuthority Author Visit, T SQL, Technology Tagged: Spatial Database

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  • SQL SERVER – SOS_SCHEDULER_YIELD – Wait Type – Day 8 of 28

    - by pinaldave
    This is a very interesting wait type and quite often seen as one of the top wait types. Let us discuss this today. From Book On-Line: Occurs when a task voluntarily yields the scheduler for other tasks to execute. During this wait the task is waiting for its quantum to be renewed. SOS_SCHEDULER_YIELD Explanation: SQL Server has multiple threads, and the basic working methodology for SQL Server is that SQL Server does not let any “runnable” thread to starve. Now let us assume SQL Server OS is very busy running threads on all the scheduler. There are always new threads coming up which are ready to run (in other words, runnable). Thread management of the SQL Server is decided by SQL Server and not the operating system. SQL Server runs on non-preemptive mode most of the time, meaning the threads are co-operative and can let other threads to run from time to time by yielding itself. When any thread yields itself for another thread, it creates this wait. If there are more threads, it clearly indicates that the CPU is under pressure. You can fun the following DMV to see how many runnable task counts there are in your system. SELECT scheduler_id, current_tasks_count, runnable_tasks_count, work_queue_count, pending_disk_io_count FROM sys.dm_os_schedulers WHERE scheduler_id < 255 GO If you notice a two-digit number in runnable_tasks_count continuously for long time (not once in a while), you will know that there is CPU pressure. The two-digit number is usually considered as a bad thing; you can read the description of the above DMV over here. Additionally, there are several other counters (%Processor Time and other processor related counters), through which you can refer to so you can validate CPU pressure along with the method explained above. Reducing SOS_SCHEDULER_YIELD wait: This is the trickiest part of this procedure. As discussed, this particular wait type relates to CPU pressure. Increasing more CPU is the solution in simple terms; however, it is not easy to implement this solution. There are other things that you can consider when this wait type is very high. Here is the query where you can find the most expensive query related to CPU from the cache Note: The query that used lots of resources but is not cached will not be caught here. SELECT SUBSTRING(qt.TEXT, (qs.statement_start_offset/2)+1, ((CASE qs.statement_end_offset WHEN -1 THEN DATALENGTH(qt.TEXT) ELSE qs.statement_end_offset END - qs.statement_start_offset)/2)+1), qs.execution_count, qs.total_logical_reads, qs.last_logical_reads, qs.total_logical_writes, qs.last_logical_writes, qs.total_worker_time, qs.last_worker_time, qs.total_elapsed_time/1000000 total_elapsed_time_in_S, qs.last_elapsed_time/1000000 last_elapsed_time_in_S, qs.last_execution_time, qp.query_plan FROM sys.dm_exec_query_stats qs CROSS APPLY sys.dm_exec_sql_text(qs.sql_handle) qt CROSS APPLY sys.dm_exec_query_plan(qs.plan_handle) qp ORDER BY qs.total_worker_time DESC -- CPU time You can find the most expensive queries that are utilizing lots of CPU (from the cache) and you can tune them accordingly. Moreover, you can find the longest running query and attempt to tune them if there is any processor offending code. Additionally, pay attention to total_worker_time because if that is also consistently higher, then  the CPU under too much pressure. You can also check perfmon counters of compilations as they tend to use good amount of CPU. Index rebuild is also a CPU intensive process but we should consider that main cause for this query because that is indeed needed on high transactions OLTP system utilized to reduce fragmentations. 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 of the discussions 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 Authority News – Presenting at SQL Bangalore on May 3, 2014 – Performing an Effective Presentation

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

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  • SQL SERVER – Database Dynamic Caching by Automatic SQL Server Performance Acceleration

    - by pinaldave
    My second look at SafePeak’s new version (2.1) revealed to me few additional interesting features. For those of you who hadn’t read my previous reviews SafePeak and not familiar with it, here is a quick brief: SafePeak is in business of accelerating performance of SQL Server applications, as well as their scalability, without making code changes to the applications or to the databases. SafePeak performs database dynamic caching, by caching in memory result sets of queries and stored procedures while keeping all those cache correct and up to date. Cached queries are retrieved from the SafePeak RAM in microsecond speed and not send to the SQL Server. The application gets much faster results (100-500 micro seconds), the load on the SQL Server is reduced (less CPU and IO) and the application or the infrastructure gets better scalability. SafePeak solution is hosted either within your cloud servers, hosted servers or your enterprise servers, as part of the application architecture. Connection of the application is done via change of connection strings or adding reroute line in the c:\windows\system32\drivers\etc\hosts file on all application servers. For those who would like to learn more on SafePeak architecture and how it works, I suggest to read this vendor’s webpage: SafePeak Architecture. More interesting new features in SafePeak 2.1 In my previous review of SafePeak new I covered the first 4 things I noticed in the new SafePeak (check out my article “SQLAuthority News – SafePeak Releases a Major Update: SafePeak version 2.1 for SQL Server Performance Acceleration”): Cache setup and fine-tuning – a critical part for getting good caching results Database templates Choosing which database to cache Monitoring and analysis options by SafePeak Since then I had a chance to play with SafePeak some more and here is what I found. 5. Analysis of SQL Performance (present and history): In SafePeak v.2.1 the tools for understanding of performance became more comprehensive. Every 15 minutes SafePeak creates and updates various performance statistics. Each query (or a procedure execute) that arrives to SafePeak gets a SQL pattern, and after it is used again there are statistics for such pattern. An important part of this product is that it understands the dependencies of every pattern (list of tables, views, user defined functions and procs). From this understanding SafePeak creates important analysis information on performance of every object: response time from the database, response time from SafePeak cache, average response time, percent of traffic and break down of behavior. One of the interesting things this behavior column shows is how often the object is actually pdated. The break down analysis allows knowing the above information for: queries and procedures, tables, views, databases and even instances level. The data is show now on all arriving queries, both read queries (that can be cached), but also any types of updates like DMLs, DDLs, DCLs, and even session settings queries. The stats are being updated every 15 minutes and SafePeak dashboard allows going back in time and investigating what happened within any time frame. 6. Logon trigger, for making sure nothing corrupts SafePeak cache data If you have an application with many parts, many servers many possible locations that can actually update the database, or the SQL Server is accessible to many DBAs or software engineers, each can access some database directly and do some changes without going thru SafePeak – this can create a potential corruption of the data stored in SafePeak cache. To make sure SafePeak cache is correct it needs to get all updates to arrive to SafePeak, and if a DBA will access the database directly and do some changes, for example, then SafePeak will simply not know about it and will not clean SafePeak cache. In the new version, SafePeak brought a new feature called “Logon Trigger” to solve the above challenge. By special click of a button SafePeak can deploy a special server logon trigger (with a CLR object) on your SQL Server that actually monitors all connections and informs SafePeak on any connection that is coming not from SafePeak. In SafePeak dashboard there is an interface that allows to control which logins can be ignored based on login names and IPs, while the rest will invoke cache cleanup of SafePeak and actually locks SafePeak cache until this connection will not be closed. Important to note, that this does not interrupt any logins, only informs SafePeak on such connection. On the Dashboard screen in SafePeak you will be able to see those connections and then decide what to do with them. Configuration of this feature in SafePeak dashboard can be done here: Settings -> SQL instances management -> click on instance -> Logon Trigger tab. Other features: 7. User management ability to grant permissions to someone without changing its configuration and only use SafePeak as performance analysis tool. 8. Better reports for analysis of performance using 15 minute resolution charts. 9. Caching of client cursors 10. Support for IPv6 Summary SafePeak is a great SQL Server performance acceleration solution for users who want immediate results for sites with performance, scalability and peak spikes challenges. Especially if your apps are packaged or 3rd party, since no code changes are done. SafePeak can significantly increase response times, by reducing network roundtrip to the database, decreasing CPU resource usage, eliminating I/O and storage access. SafePeak team provides a free fully functional trial www.safepeak.com/download and actually provides a one-on-one assistance during such trial. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: About Me, Pinal Dave, PostADay, SQL, SQL Authority, SQL Performance, SQL Query, SQL Server, SQL Tips and Tricks, SQL Utility, T SQL, Technology

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  • SQLAuthority News – Download SQL Azure Labs Codename “Data Explorer” Client

    - by pinaldave
    Microsoft SQL Azure labs has recently released Data Explorer client. I was looking forward to visualizing tool for quite a while and I am delighted to see this tool. I will be trying out this tool in coming week and will post here my experience. I have listed few of the resources which are related to Data Explorer at the end. Please let me know if I have missed any and I will add the same. With “Data Explorer” you can: Identify the data you care about from the sources you work with (e.g. Excel spreadsheets, files, SQL Server databases). Discover relevant data and services via automatic recommendations from the Windows Azure Marketplace. Enrich your data by combining it and visualizing the results. Collaborate with your colleagues to refine the data. Publish the results to share them with others or power solutions. The Data Explorer Client package contains the Data Explorer workspace as well as an Office plugin that integrates Data Explorer into Excel. Resources: Download Data Explorer Data Explorer Blog Desktop Client Video of  Contoso Bikes and Frozen Yogurt (Data Explorer) Please note that this is not the final release of the product. Please do not attempt this on production server. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: PostADay, SQL, SQL Authority, SQL Azure, SQL Documentation, SQL Download, SQL Query, SQL Server, SQL Tips and Tricks, SQLAuthority News, T SQL, Technology

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  • SQLAuthority News – Public Training Classes In Hyderabad 12-14 May – SQL and 10-11 May SharePoint

    - by pinaldave
    There were lots of request about providing more details for the blog post through email address specified in the article SQLAuthority News – Public Training Classes In Hyderabad 12-14 May – Microsoft SQL Server 2005/2008 Query Optimization & Performance Tuning. Here is the complete brochure of the course. There are two different courses are offered by Solid Quality Mentors 1) Microsoft SQL Server 2005/2008 Query Optimization & Performance Tuning – Pinal Dave Date: May 12-14, 2010 Price: Rs. 14,000/person for 3 days Discount Code: ‘SQLAuthority.com‘ Effective Price: Rs. 11,000/person for 3 days 2) SharePoint 2010 – Joy Rathnayake Date: May 10-11, 2010 Price: Rs. 11,000/person for 3 days Discount Code: ‘SQLAuthority.com’ Effective Price: Rs. 8,000/person for 3 days Download the complete PDF brochure. Additionally there is special program of SolidQ India Insider. I will provide the details for the same very soon. Please do send me email if you need any additional details. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, SQL, SQL Authority, SQL Optimization, SQL Performance, SQL Query, SQL Server, SQL Tips and Tricks, SQL Training, SQLAuthority News, T SQL, Technology

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  • SQL SERVER – Index Created on View not Used Often – Limitation of the View 12

    - by pinaldave
    I have previously written on the subject SQL SERVER – The Limitations of the Views – Eleven and more…. This was indeed a very popular series and I had received lots of feedback on that topic. Today we are going to discuss something very interesting as well. During my recent performance tuning seminar in Hyderabad, I presented on the subject of Views. During the seminar, one of the attendees asked a question: We create a table and create a View on the top of it. On the same view, if we create Index, when querying View, will that index be used? The answer is NOT Always! (There is only one specific condition when it will be used. We will write about that later in the next post). Let us see the test case for the same. In our script we will do following: USE tempdb GO IF EXISTS (SELECT * FROM sys.views WHERE OBJECT_ID = OBJECT_ID(N'[dbo].[SampleView]')) DROP VIEW [dbo].[SampleView] GO IF EXISTS (SELECT * FROM sys.objects WHERE OBJECT_ID = OBJECT_ID(N'[dbo].[mySampleTable]') AND TYPE IN (N'U')) DROP TABLE [dbo].[mySampleTable] GO -- Create SampleTable CREATE TABLE mySampleTable (ID1 INT, ID2 INT, SomeData VARCHAR(100)) INSERT INTO mySampleTable (ID1,ID2,SomeData) SELECT TOP 100000 ROW_NUMBER() OVER (ORDER BY o1.name), ROW_NUMBER() OVER (ORDER BY o2.name), o2.name FROM sys.all_objects o1 CROSS JOIN sys.all_objects o2 GO -- Create View CREATE VIEW SampleView WITH SCHEMABINDING AS SELECT ID1,ID2,SomeData FROM dbo.mySampleTable GO -- Create Index on View CREATE UNIQUE CLUSTERED INDEX [IX_ViewSample] ON [dbo].[SampleView] ( ID2 ASC ) GO -- Select from view SELECT ID1,ID2,SomeData FROM SampleView GO Let us check the execution plan for the last SELECT statement. You can see from the execution plan. That even though we are querying View and the View has index, it is not really using that index. In the next post, we will see the significance of this View and where it can be helpful. Meanwhile, I encourage you to read my View series: SQL SERVER – The Limitations of the Views – Eleven and more…. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: Pinal Dave, SQL, SQL Authority, SQL Query, SQL Scripts, SQL Server, SQL Tips and Tricks, SQL Training, SQL View, T SQL, Technology

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  • SQLAuthority News – Public Training Classes In Hyderabad 12-14 May – SQL and 10-11 May SharePoint

    - by pinaldave
    There were lots of request about providing more details for the blog post through email address specified in the article SQLAuthority News – Public Training Classes In Hyderabad 12-14 May – Microsoft SQL Server 2005/2008 Query Optimization & Performance Tuning. Here is the complete brochure of the course. There are two different courses are offered by Solid Quality Mentors 1) Microsoft SQL Server 2005/2008 Query Optimization & Performance Tuning – Pinal Dave Date: May 12-14, 2010 Price: Rs. 14,000/person for 3 days Discount Code: ‘SQLAuthority.com‘ Effective Price: Rs. 11,000/person for 3 days 2) SharePoint 2010 – Joy Rathnayake Date: May 10-11, 2010 Price: Rs. 11,000/person for 3 days Discount Code: ‘SQLAuthority.com’ Effective Price: Rs. 8,000/person for 3 days Download the complete PDF brochure. Additionally there is special program of SolidQ India Insider. I will provide the details for the same very soon. Please do send me email if you need any additional details. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, SQL, SQL Authority, SQL Optimization, SQL Performance, SQL Query, SQL Server, SQL Tips and Tricks, SQL Training, SQLAuthority News, T SQL, Technology

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  • SQL SERVER – Introduction to CUME_DIST – Analytic Functions Introduced in SQL Server 2012

    - by pinaldave
    This blog post is written in response to the T-SQL Tuesday post of Prox ‘n’ Funx. This is a very interesting subject. By the way Brad Schulz is my favorite guy when it is about blogging. I respect him as well learn a lot from him. Everybody is writing something new his subject, I decided to start SQL Server 2012 analytic functions series. SQL Server 2012 introduces new analytical function CUME_DIST(). This function provides cumulative distribution value. It will be very difficult to explain this in words so I will attempt small example to explain you this function. Instead of creating new table, I will be using AdventureWorks sample database as most of the developer uses that for experiment. Let us fun following query. USE AdventureWorks GO SELECT SalesOrderID, OrderQty, CUME_DIST() OVER(ORDER BY SalesOrderID) AS CDist FROM Sales.SalesOrderDetail WHERE SalesOrderID IN (43670, 43669, 43667, 43663) ORDER BY CDist DESC GO Above query will give us following result. Now let us understand what is the formula behind CUME_DIST and why the values in SalesOrderID = 43670 are 1. Let us take more example and be clear about why the values in SalesOrderID = 43667 are 0.5. Now let us enhence the same example and use PARTITION BY into the OVER clause and see the results. Run following query in SQL Server 2012. USE AdventureWorks GO SELECT SalesOrderID, OrderQty, ProductID, CUME_DIST() OVER(PARTITION BY SalesOrderID ORDER BY ProductID ) AS CDist FROM Sales.SalesOrderDetail s WHERE SalesOrderID IN (43670, 43669, 43667, 43663) ORDER BY s.SalesOrderID DESC, CDist DESC GO Now let us see the result of this query. We are have changed the ORDER BY clause as well partitioning by SalesOrderID. You can see that CUME_DIST() function provides us different results. Additionally now we see value 1 multiple times. As we are using partitioning for each group of SalesOrderID we get the CUME_DIST() value. CUME_DIST() was long awaited Analytical function and I am glad to see it in SQL Server 2012. 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 – SSMS: Memory Usage By Memory Optimized Objects Report

    - by Pinal Dave
    At conferences and at speaking engagements at the local UG, there is one question that keeps on coming which I wish were never asked. The question around, “Why is SQL Server using up all the memory and not releasing even when idle?” Well, the answer can be long and with the release of SQL Server 2014, this got even more complicated. This release of SQL Server 2014 has the option of introducing In-Memory OLTP which is completely new concept and our dependency on memory has increased multifold. In reality, nothing much changes but we have memory optimized objects (Tables and Stored Procedures) additional which are residing completely in memory and improving performance. As a DBA, it is humanly impossible to get a hang of all the innovations and the new features introduced in the next version. So today’s blog is around the report added to SSMS which gives a high level view of this new feature addition. This reports is available only from SQL Server 2014 onwards because the feature was introduced in SQL Server 2014. Earlier versions of SQL Server Management Studio would not show the report in the list. If we try to launch the report on the database which is not having In-Memory File group defined, then we would see the message in report. To demonstrate, I have created new fresh database called MemoryOptimizedDB with no special file group. Here is the query used to identify whether a database has memory-optimized file group or not. SELECT TOP(1) 1 FROM sys.filegroups FG WHERE FG.[type] = 'FX' Once we add filegroup using below command, we would see different version of report. USE [master] GO ALTER DATABASE [MemoryOptimizedDB] ADD FILEGROUP [IMO_FG] CONTAINS MEMORY_OPTIMIZED_DATA GO The report is still empty because we have not defined any Memory Optimized table in the database.  Total allocated size is shown as 0 MB. Now, let’s add the folder location into the filegroup and also created few in-memory tables. We have used the nomenclature of IMO to denote “InMemory Optimized” objects. USE [master] GO ALTER DATABASE [MemoryOptimizedDB] ADD FILE ( NAME = N'MemoryOptimizedDB_IMO', FILENAME = N'E:\Program Files\Microsoft SQL Server\MSSQL12.SQL2014\MSSQL\DATA\MemoryOptimizedDB_IMO') TO FILEGROUP [IMO_FG] GO You may have to change the path based on your SQL Server configuration. Below is the script to create the table. USE MemoryOptimizedDB GO --Drop table if it already exists. IF OBJECT_ID('dbo.SQLAuthority','U') IS NOT NULL DROP TABLE dbo.SQLAuthority GO CREATE TABLE dbo.SQLAuthority ( ID INT IDENTITY NOT NULL, Name CHAR(500)  COLLATE Latin1_General_100_BIN2 NOT NULL DEFAULT 'Pinal', CONSTRAINT PK_SQLAuthority_ID PRIMARY KEY NONCLUSTERED (ID), INDEX hash_index_sample_memoryoptimizedtable_c2 HASH (Name) WITH (BUCKET_COUNT = 131072) ) WITH (MEMORY_OPTIMIZED = ON, DURABILITY = SCHEMA_AND_DATA) GO As soon as above script is executed, table and index both are created. If we run the report again, we would see something like below. Notice that table memory is zero but index is using memory. This is due to the fact that hash index needs memory to manage the buckets created. So even if table is empty, index would consume memory. More about the internals of how In-Memory indexes and tables work will be reserved for future posts. Now, use below script to populate the table with 10000 rows INSERT INTO SQLAuthority VALUES (DEFAULT) GO 10000 Here is the same report after inserting 1000 rows into our InMemory table.    There are total three sections in the whole report. Total Memory consumed by In-Memory Objects Pie chart showing memory distribution based on type of consumer – table, index and system. Details of memory usage by each table. The information about all three is taken from one single DMV, sys.dm_db_xtp_table_memory_stats This DMV contains memory usage statistics for both user and system In-Memory tables. If we query the DMV and look at data, we can easily notice that the system tables have negative object IDs.  So, to look at user table memory usage, below is the over-simplified version of query. USE MemoryOptimizedDB GO SELECT OBJECT_NAME(OBJECT_ID), * FROM sys.dm_db_xtp_table_memory_stats WHERE OBJECT_ID > 0 GO This report would help DBA to identify which in-memory object taking lot of memory which can be used as a pointer for designing solution. I am sure in future we will discuss at lengths the whole concept of In-Memory tables in detail over this blog. To read more about In-Memory OLTP, have a look at In-Memory OLTP Series at Balmukund’s Blog. Reference: Pinal Dave (http://blog.sqlauthority.com)Filed under: PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Server Management Studio, SQL Tips and Tricks, T SQL Tagged: SQL Memory, SQL Reports

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  • SQL SERVER – How to Change Compatibility of Database to SQL Server 2014

    - by Pinal Dave
    Yesterday I wrote about how we can install SQL Server 2014. Right after the blog post was live, I received a question from the developer that he has installed SQL Server 2014 and attached a database file from previous version of SQL Server. Right after attaching database, he was not able to work with the latest features of Cardinality Estimation. As soon as he sent me email I realize what has happened exactly. When he attached database, the database compatibility was set to still of the earlier version of SQL Server. To use most of the latest features of SQL Server 2014, one has to change the compatibility level of the database to the latest version (i.e. 120). Here are two different ways how we can change the compatibility of database to SQL Server 2014′s version. 1) Using Management Studio For this method first to go database and right click over it. Now select properties. On this screen user can change the compatibility level to 120. 2) Using T-SQL Script. You can execute following script and change the compatibility settings to 120. USE [master] GO ALTER DATABASE [AdventureWorks2012] SET COMPATIBILITY_LEVEL = 120 GO   Well, it is that easy :-) 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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  • SQLAuthority News – Presented Soft Skill Session on Presentation Skills at SQL Bangalore on May 3, 2014

    - by Pinal Dave
    I have presented on various database technologies for almost 10 years now. SQL, Database and NoSQL have been part of my life. Earlier this month, I had the opportunity to present on the topic Performing an Effective Presentation. I must say it was blast to prepare as well as present this session. This event was part of the SQL Bangalore community. If you are in Bangalore, you must be part of this group. SQL Bangalore is a wonderful community and we always have a great response when we present on technology. It is SQL User Group and we discuss everything SQL there. This month we had SQL Server 2014 theme and we had a community launch of SQL Server. We have the best of the best speakers presenting on SQL Server 2014 technology. The event had amazing speakers and each of them did justice to the subject. You can read about this over here. In this session I told a story from my life. I talked about who inspired me and how I learned to speak in public. I told stories about two legends  who have inspired me. There is no video recording of this session. If you want to get resources from this session, please sign up my newsletter at http://bit.ly/sqllearn. Well, I had a great time at this event. We had over 250 people showed up at this event and had a grand  time together. I personally enjoyed a session of Amit Benerjee, Balmukund Lakhani and Vinod Kumar. Ken and Surabh also entertained the audience. Overall, this was a grand event and if you were in Bangalore and did not make it to this event. You did miss out on a few things. Here are a few photos of this event. SQL Bangalore UG Nupur, Chandra, Shaivi, Balmukund, Amit, Vinod [captions This] SQL Bangalore UG Audience Pinal Dave presenting at SQL UG in Bangalore Here are few of the slides from this presentation: 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

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  • SQL SERVER – Out of the Box – Activty and Performance Reports from SSSMS

    - by pinaldave
    SQL Server management Studio 2008 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. Let us see how we can access these standard reports. Connect to SQL Server Node >> Right Click on it >> Go to Reports >> Click on Standard Reports >> Pick Any Report. Click to Enlarge You can see there are many reports, which an average users needs right away, are available there. Let me list all the reports available. Server Dashboard Configuration Changes History Schema Changes History Scheduler Health Memory Consumption Activity – All Blocking Transactions Activity – All Cursors Activity – All Sessions Activity – Top Sessions Activity – Dormant Sessions Activity -  Top Connections Top Transactions by Age Top Transactions by Blocked Transactions Count Top Transactions by Locks Count Performance – Batch Execution Statistics Performance – Object Execution Statistics Performance – Top Queries by Average CPU Time Performance – Top Queries by Average IO Performance – Top Queries by Total CPU Time Performance – Top Queries by Total IO Service Broker Statistics Transactions Log Shipping Status In fact, when you look at the above list, it is fairly clear that they are very thought out and commonly needed reports that are available in SQL Server 2008. Let us run a couple of reports and observe their result. Performance – Top Queries by Total CPU Time Click to Enlarge Memory Consumption Click to Enlarge There are options for custom reports as well, which we can configure. We will learn about them in some other post. Additionally, you can right click on the reports and export in Excel or PDF. I think this tool can really help those who are just looking for some quick details. Does any of you use this feature, or this feature has some limitations and You would like to see more features? Reference : Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, SQL, SQL Authority, SQL Optimization, SQL Performance, SQL Query, SQL Server, SQL Server Management Studio, SQL Tips and Tricks, T SQL, Technology

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  • SQLAuthority News – A Successful Performance Tuning Seminar at Pune – Dec 4-5, 2010

    - by pinaldave
    This is report to my third of very successful seminar event on SQL Server Performance Tuning. SQL Server Performance Tuning Seminar in Colombo was oversubscribed with total of 35 attendees. You can read the details over here SQLAuthority News – SQL Server Performance Optimizations Seminar – Grand Success – Colombo, Sri Lanka – Oct 4 – 5, 2010. SQL Server Performance Tuning Seminar in Hyderabad was oversubscribed with total of 25 attendees. You can read the details over here SQL SERVER – A Successful Performance Tuning Seminar – Hyderabad – Nov 27-28, 2010. The same Seminar was offered in Pune on December 4,-5, 2010. We had another successful seminar with lots of performance talk. This seminar was attended by 30 attendees. The best part of the seminar was that along with the our agenda, we have talked about following very interesting concepts. Deadlocks Detection and Removal Dynamic SQL and Inline Code SQL Optimizations Multiple OR conditions and performance tuning Dynamic Search Condition Building and Improvement Memory Cache and Improvement Bottleneck Detections – Memory, CPU and IO Beginning Performance Tuning on Production Parametrization Improving already Super Fast Queries Convenience vs. Performance Proper way to create Indexes Hints and Disadvantages I had great time doing the seminar and sharing my performance tricks with all. The highlight of this seminar was I have explained the attendees, how I begin doing performance tuning when I go for Performance Tuning Consultations.   Pinal Dave at SQL Performance Tuning Seminar SQL Server Performance Tuning Seminar Pinal Dave at SQL Performance Tuning Seminar Pinal Dave at SQL Performance Tuning Seminar SQL Server Performance Tuning Seminar SQL Server Performance Tuning Seminar This seminar series are 100% demo oriented and no usual PowerPoint talk. They are created from my experiences of various organizations for performance tuning. I am not planning any more seminar this year as it was great but I am booked currently for next 60 days at various performance tuning engagements. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: Pinal Dave, SQL, SQL Authority, SQL Optimization, SQL Performance, SQL Query, SQL Server, SQL Tips and Tricks, SQL Training, SQLAuthority News, T SQL, Technology

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  • SQLAuthority News – Microsoft SQL Server 2005/2008 Query Optimization & Performance Tuning Training

    - by pinaldave
    Last 3 days to register for the courses. This is one time offer with big discount. The deadline for the course registration is 5th May, 2010. There are two different courses are offered by Solid Quality Mentors 1) Microsoft SQL Server 2005/2008 Query Optimization & Performance Tuning – Pinal Dave Date: May 12-14, 2010 Price: Rs. 14,000/person for 3 days Discount Code: ‘SQLAuthority.com’ Effective Price: Rs. 11,000/person for 3 days 2) SharePoint 2010 – Joy Rathnayake Date: May 10-11, 2010 Price: Rs. 11,000/person for 3 days Discount Code: ‘SQLAuthority.com’ Effective Price: Rs. 8,000/person for 2 days Download the complete PDF brochure. To register, either send an email to [email protected] or call +91 95940 43399. Feel free to drop me an email at pinal “at” SQLAuthority.com for any additional information and clarification. Training Venue: Abridge Solutions, #90/B/C/3/1, Ganesh GHR & MSY Plaza, Vittalrao Nagar, Near Image Hospital, Madhapur, Hyderabad – 500 081. Additionally there is special program of SolidQ India Insider. This is only available to first few registrants of the courses only. Read more details about the course here. Read my TechEd India 2010 experience here. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, SQL, SQL Authority, SQL Optimization, SQL Performance, SQL Query, SQL Server, SQL Tips and Tricks, SQL Training, SQLAuthority News, T SQL, Technology

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  • SQL Server – Learning SQL Server Performance: Indexing Basics – Video

    - by pinaldave
    Today I remember one of my older cartoon years ago created for Indexing and Performance. Every single time when Performance is discussed, Indexes are mentioned along with it. In recent times, data and application complexity is continuously growing.  The demand for faster query response, performance, and scalability by organizations is increasing and developers and DBAs need to now write efficient code to achieve this. DBA and Developers 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, analysing, and maintaining indexes. Though we have learnt indexing concepts from our college days, indexing implementation inside SQL Server can vary.  Understanding this behaviour and designing our applications appropriately will make sure the application is performed to its highest potential. Video Learning 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. We decided to build a course which just addresses the practical aspects of the performance. In this course, we explored some of these indexing fundamentals and we elaborated on how SQL Server goes about using indexes.  At the end of this course of you will know the basic structure of indexes, practical insights into implementation, and maintenance tips and tricks revolving around indexes.  Finally, we will introduce SQL Server 2012 column store indexes.  We have refrained from discussing internal storage structure of the indexes but have taken a more practical, demo-oriented approach to explain these core concepts. Course Outline Here are salient topics of the course. We have explained every single concept along with a practical demonstration. Additionally shared our personal scripts along with the same. Introduction Fundamentals of Indexing Index Fundamentals Index Fundamentals – Visual Representation Practical Indexing Implementation Techniques Primary Key Over Indexing Duplicate Index Clustered Index Unique Index Included Columns Filtered Index Disabled Index Index Maintenance and Defragmentation Introduction to Columnstore Index Indexing Practical Performance Tips and Tricks Index and Page Types Index and Non Deterministic Columns Index and SET Values Importance of Clustered Index Effect of Compression and Fillfactor Index and Functions Dynamic Management Views (DMV) – Fillfactor Table Scan, Index Scan and Index Seek Index and Order of Columns Final Checklist: Index and Performance Well, we believe we have done our part, now waiting for your comments and feedback. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: PostADay, SQL, SQL Authority, SQL Index, SQL Performance, SQL Query, SQL Server, SQL Tips and Tricks, SQLServer, T SQL, Technology, Video

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  • SQLAuthority News – Statistics and Best Practices – Virtual Tech Days – Nov 22, 2010

    - by pinaldave
    I am honored that I have been invited to speak at Virtual TechDays on Nov 22, 2010 by Microsoft. I will be speaking on my favorite subject of Statistics and Best Practices. This exclusive online event will have 80 deep technical sessions across 3 days – and, attendance is completely FREE. There are dedicated tracks for Architects, Software Developers/Project Managers, Infrastructure Managers/Professionals and Enterprise Developers. So, REGISTER for this exclusive online event TODAY. Statistics and Best Practices Timing: 11:45am-12:45pm Statistics are a key part of getting solid performance. In this session we will go over the basics of the statistics and various best practices related to Statistics. We will go over various frequently asked questions like a) when to update statistics, b) different between sync and async update of statistics c) best method to update statistics d) optimal interval of updating statistics. We will also discuss the pros and cons of the statistics update. This session is for all of you – whether you’re a DBA or developer! You can register for this event over here. If you have never attended my session on this subject I strongly suggest that you attend the event as this is going to be very interesting conversation between us. If you have attended this session earlier, this will contain few new information which will for sure interesting to share with all. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: MVP, Pinal Dave, SQL, SQL Authority, SQL Joins, SQL Optimization, SQL Performance, SQL Query, SQL Server, SQL Tips and Tricks, SQLAuthority News, T SQL, Technology Tagged: SQL Statistics, Statistics

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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 – Public Training and Private Training – Differences and Similarities

    - by pinaldave
    Earlier this year, I was on Road SQL Server Seminars. I did many SQL Server Performance Trainings and SQL Server Performance Consultations throughout the year but I feel the most rewarding exercise is always the one when instructor learns something from students, too. I was just talking to my wife, Nupur – she manages my logistics and administration related activities – and she pointed out that this year I have done 62% consultations and 38% trainings. I was bit surprised as I thought the numbers would be reversed. Every time I review the year, I think of training done at organizations. Well, I cannot argue with reality, I have done more consultations (some would call them projects) than training. I told my wife that I enjoy consultations more than training. She promptly asked me a question which was not directly related but made me think for long time, and in the end resulted in this blog post. Nupur asked me: what do I enjoy the most, public training or private training? I had a long conversation with her on this subject. I am not going to write long blog post which can change your life here. This is rather a small post condensing my one hour discussion into 200 words. Public Training is fun because… There are lots of different kinds of attendees There are always vivid questions Lots of questions on questions Less interest in theory and more interest in demos Good opportunity of future business Private Training is fun because… There is a focused interest One question is discussed deeply because of existing company issues More interest in “how it happened” concepts – under the hood operations Good connection with attendees This is also a good opportunity of future business Here I will stop my monologue and I want to open up this question to all of you: Question to Attendees - Which one do you enjoy the most – Public Training or Private Training? Question to Trainers - What do you enjoy the most – Public Training or Private Training? Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: Pinal Dave, SQL, SQL Authority, SQL Optimization, SQL Performance, SQL Query, SQL Server, SQL Tips and Tricks, SQL Training, SQLAuthority News, T SQL, Technology

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  • SQL SERVER – Three Puzzling Questions – Need Your Answer

    - by pinaldave
    Last week I had asked three questions on my blog. I got very good response to the questions. I am planning to write summary post for each of three questions next week. Before I write summary post and give credit to all the valid answers. I was wondering if I can bring to notice of all of you this week. Why SELECT * throws an error but SELECT COUNT(*) does not This is indeed very interesting question as not quite many realize that this kind of behavior SQL Server demonstrates out of the box. Once you run both the code and read the explanation it totally makes sense why SQL Server is behaving how it is behaving. Also there is connect item is associated with it. Also read the very first comment by Rob Farley it also shares very interesting detail. Statistics are not Updated but are Created Once This puzzle has multiple right answer. I am glad to see many of the correct answer as a comment to this blog post. Statistics are very important and it really helps SQL Server Engine to come up with optimal execution plan. DBA quite often ignore statistics thinking it does not need to be updated, as they are automatically maintained if proper database setting is configured (auto update and auto create). Well, in this question, we have scenario even though auto create and auto update statistics are ON, statistics is not updated. There are multiple solutions but what will be your solution in this case? When to use Function and When to use Stored Procedure This question is rather open ended question – there is no right or wrong answer. Everybody developer has always used functions and stored procedures. Here is the chance to justify when to use Stored Procedure and when to use Functions. I want to acknowledge that they can be used interchangeably but there are few reasons when one should not do that. There are few reasons when one is better than other. Let us discuss this here. Your opinion matters. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, PostADay, Readers Contribution, Readers Question, SQL, SQL Authority, SQL Performance, SQL Puzzle, SQL Query, SQL Scripts, SQL Server, SQL Tips and Tricks, SQLAuthority News, SQLServer, T SQL, Technology

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  • SQL SERVER – Video – Beginning Performance Tuning with SQL Server Execution Plan

    - by pinaldave
    Traveling can be most interesting or most exhausting experience. However, traveling is always the most enlightening experience one can have. While going to long journey one has to prepare a lot of things. Pack necessary travel gears, clothes and medicines. However, the most essential part of travel is the journey to the destination. There are many variations one prefer but the ultimate goal is to have a delightful experience during the journey. Here is the video available which explains how to begin with SQL Server Execution plans. Performance Tuning is a Journey Performance tuning is just like a long journey. The goal of performance tuning is efficient and least resources consuming query execution with accurate results. Just as maps are the most essential aspect of performance tuning the same way, execution plans are essentially maps for SQL Server to reach to the resultset. The goal of the execution plan is to find the most efficient path which translates the least usage of the resources (CPU, memory, IO etc). Execution Plans are like Maps When online maps were invented (e.g. Bing, Google, Mapquests etc) initially it was not possible to customize them. They were given a single route to reach to the destination. As time evolved now it is possible to give various hints to the maps, for example ‘via public transport’, ‘walking’, ‘fastest route’, ‘shortest route’, ‘avoid highway’. There are places where we manually drag the route and make it appropriate to our needs. The same situation is with SQL Server Execution Plans, if we want to tune the queries, we need to understand the execution plans and execution plans internals. We need to understand the smallest details which relate to execution plan when we our destination is optimal queries. Understanding Execution Plans The biggest challenge with maps are figuring out the optimal path. The same way the  most common challenge with execution plans is where to start from and which precise route to take. Here is a quick list of the frequently asked questions related to execution plans: Should I read the execution plans from bottoms up or top down? Is execution plans are left to right or right to left? What is the relational between actual execution plan and estimated execution plan? When I mouse over operator I see CPU and IO but not memory, why? Sometime I ran the query multiple times and I get different execution plan, why? How to cache the query execution plan and data? I created an optimal index but the query is not using it. What should I change – query, index or provide hints? What are the tools available which helps quickly to debug performance problems? Etc… Honestly the list is quite a big and humanly impossible to write everything in the words. SQL Server Performance:  Introduction to Query Tuning My friend Vinod Kumar and I have created for the same a video learning course for beginning performance tuning. We have covered plethora of the subject in the course. Here is the quick list of the same: Execution Plan Basics Essential Indexing Techniques Query Design for Performance Performance Tuning Tools Tips and Tricks Checklist: Performance Tuning We believe we have covered a lot in this four hour course and we encourage you to go over the video course if you are interested in Beginning SQL Server Performance Tuning and Query Tuning. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: PostADay, SQL, SQL Authority, SQL Optimization, SQL Performance, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology, Video Tagged: Execution Plan

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  • SQL SERVER – Weekend Project – Experimenting with ACID Transactions, SQL Compliant, Elastically Scalable Database

    - by pinaldave
    Database technology is huge and big world. I like to explore always beyond what I know and share the learning. Weekend is the best time when I sit around download random software on my machine which I like to call as a lab machine (it is a pretty old laptop, hardly a quality as lab machine) and experiment it. There are so many free betas available for download that it’s hard to keep track and even harder to find the time to play with very many of them.  This blog is about one you shouldn’t miss if you are interested in the learning various relational databases. NuoDB just released their Beta 7.  I had already downloaded their Beta 6 and yesterday did the same for 7.   My impression is that they are onto something very very interesting.  In fact, it might be something really promising in terms of database elasticity, scale and operational cost reduction. The folks at NuoDB say they are working on the world’s first “emergent” database which they tout as a brand new transitional database that is intended to dramatically change what’s possible with OLTP.  It is SQL compliant, guarantees ACID transactions, yet scales elastically on heterogeneous and decentralized cloud-based resources. Interesting note for sure, making me explore more. Based on what I’ve seen so far, they are solving the architectural challenge that exists between elastic, cloud-based compute infrastructures designed to scale out in response to workload requirements versus the traditional relational database management system’s architecture of central control. Here’s my experience with the NuoDB Beta 6 so far: First they pretty much threw away all the features you’d associate with existing RDBMS architectures except the SQL and ACID transactions which they were smart to keep.  It looks like they have incorporated a number of the big ideas from various algorithms, systems and techniques to achieve maximum DB scalability. From a user’s perspective, the NuoDB Beta software behaves like any other traditional SQL database and seems to offer all the benefits users have come to expect from standards-based SQL solutions. One of the interesting feature is that one can run a transactional node and a storage node on my Windows laptop as well on other platforms – indeed interesting for sure. It’s quite amazing to see a database elastically scale across machine boundaries. So, one of the basic NuoDB concepts is that as you need to scale out, you can easily use more inexpensive hardware when/where you need it.  This is unlike what we have traditionally done to scale a database for an application – we replace the hardware with something more powerful (faster CPU and Disks). This is where I started to feel like NuoDB is on to something that has the potential to elastically scale on commodity hardware while reducing operational expense for a big OLTP database to a degree we’ve never seen before. NuoDB is able to fully leverage the cloud in an asynchronous and highly decentralized manner – while providing both SQL compliance and ACID transactions. Basically what NuoDB is doing is so new that it is all hard to believe until you’ve experienced it in action.  I will keep you up to date as I test the NuoDB Beta 7 but if you are developing a web-scale application or have an on-premise app you are thinking of moving to the cloud, testing this beta is worth your time. If you do try it, let me know what you think.  Before I say anything more, I am going to do more experiments and more test on this product and compare it with other existing similar products. For me it was a weekend worth spent on learning something new. I encourage you to download Beta 7 version and share your opinions here. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: PostADay, SQL, SQL Authority, SQL Documentation, SQL Download, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology

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  • SQL SERVER – How to Ignore Columnstore Index Usage in Query

    - by pinaldave
    Earlier I wrote about SQL SERVER – Fundamentals of Columnstore Index and very first question I received in email was as following. “We are using SQL Server 2012 CTP3 and so far so good. In our data warehouse solution we have created 1 non-clustered columnstore index on our large fact table. We have very unique situation but your article did not cover it. We are running few queries on our fact table which is working very efficiently but there is one query which earlier was running very fine but after creating this non-clustered columnstore index this query is running very slow. We dropped the columnstore index and suddenly this one query is running fast but other queries which were benefited by this columnstore index it is running slow. Any workaround in this situation?” In summary the question in simple words “How can we ignore using columnstore index in selective queries?” Very interesting question – you can use I can understand there may be the cases when columnstore index is not ideal and needs to be ignored the same. You can use the query hint IGNORE_NONCLUSTERED_COLUMNSTORE_INDEX to ignore the columnstore index. SQL Server Engine will use any other index which is best after ignoring the columnstore index. Here is the quick script to prove the same. We will first create sample database and then create columnstore index on the same. Once columnstore index is created we will write simple query. This query will use columnstore index. We will then show the usage of the query hint. USE AdventureWorks GO -- Create New Table CREATE TABLE [dbo].[MySalesOrderDetail]( [SalesOrderID] [int] NOT NULL, [SalesOrderDetailID] [int] NOT NULL, [CarrierTrackingNumber] [nvarchar](25) NULL, [OrderQty] [smallint] NOT NULL, [ProductID] [int] NOT NULL, [SpecialOfferID] [int] NOT NULL, [UnitPrice] [money] NOT NULL, [UnitPriceDiscount] [money] NOT NULL, [LineTotal] [numeric](38, 6) NOT NULL, [rowguid] [uniqueidentifier] NOT NULL, [ModifiedDate] [datetime] NOT NULL ) ON [PRIMARY] GO -- Create clustered index CREATE CLUSTERED INDEX [CL_MySalesOrderDetail] ON [dbo].[MySalesOrderDetail] ( [SalesOrderDetailID]) GO -- Create Sample Data Table -- WARNING: This Query may run upto 2-10 minutes based on your systems resources INSERT INTO [dbo].[MySalesOrderDetail] SELECT S1.* FROM Sales.SalesOrderDetail S1 GO 100 -- Create ColumnStore Index CREATE NONCLUSTERED COLUMNSTORE INDEX [IX_MySalesOrderDetail_ColumnStore] ON [MySalesOrderDetail] (UnitPrice, OrderQty, ProductID) GO Now we have created columnstore index so if we run following query it will use for sure the same index. -- Select Table with regular Index SELECT ProductID, SUM(UnitPrice) SumUnitPrice, AVG(UnitPrice) AvgUnitPrice, SUM(OrderQty) SumOrderQty, AVG(OrderQty) AvgOrderQty FROM [dbo].[MySalesOrderDetail] GROUP BY ProductID ORDER BY ProductID GO We can specify Query Hint IGNORE_NONCLUSTERED_COLUMNSTORE_INDEX as described in following query and it will not use columnstore index. -- Select Table with regular Index SELECT ProductID, SUM(UnitPrice) SumUnitPrice, AVG(UnitPrice) AvgUnitPrice, SUM(OrderQty) SumOrderQty, AVG(OrderQty) AvgOrderQty FROM [dbo].[MySalesOrderDetail] GROUP BY ProductID ORDER BY ProductID OPTION (IGNORE_NONCLUSTERED_COLUMNSTORE_INDEX) GO Let us clean up the database. -- Cleanup DROP INDEX [IX_MySalesOrderDetail_ColumnStore] ON [dbo].[MySalesOrderDetail] GO TRUNCATE TABLE dbo.MySalesOrderDetail GO DROP TABLE dbo.MySalesOrderDetail GO Again, make sure that you use hint sparingly and understanding the proper implication of the same. Make sure that you test it with and without hint and select the best option after review of your administrator. Here is the question for you – have you started to use SQL Server 2012 for your validation and development (not on production)? It will be interesting to know the answer. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: PostADay, SQL, SQL Authority, SQL Index, SQL Optimization, SQL Performance, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology

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