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  • Which tool / technology: System management for databases and dependent services

    - by Filburt
    I'm looking for advice on how to enable our team to take down and re-start our company systems for maintainance purposes. The scenario includes several Oracle db machines several MS SQL Server machines with multiple instances windows services (IIS etc.) BizTalk EAI solution Apache and Tomcat instances lots of scheduled tasks on win2003 and win2008 machines (physical and virtual). The main focus is on capture all dependencies between said databases and services and tasks connecting to them. At the moment an enterprise class solution is not an option. We are considering developing a solution driven by PowerShell scripts but I hope for some more suggestions.

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  • books on web server technology

    - by tushar
    i need to understand the web server technologies as to how are the packets recieved how does it respond and understand httpd.conf files and also get to undertand what terms like proxy or reverse proxy actually mean. but i could not find any resources so please help me and suggest some ebook or web site and by server i dont mean a specific one (apache or nginx..) in short a book on understanding the basics about a web server i already asked this on stackoverflow and webmasters in a nutshell was the answer i got and they said its better if i ask it here so please help me out

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  • 50 Billion Served: Java Embedded on Devices

    - by Tori Wieldt
    It doesn't matter if it is 50 billion or 24 billion, just suffice it to stay that there will be MANY connected devices in the year 2020. With just 24 billion devices, they will outnumber humans six to one! So as a developer, you don't want to ignore this opportunity. What if you could use your Java skills and deploy an app to a fraction of these devices (don't be greedy, how about just, say, 118,000 of them)? Fareed Suliman, Java ME Product Manager had lots of good news for Java Developers in his presentation Modernizing the Explosion of Advanced Microcontrollers with Embedded Java at ARM TechCon in Santa Clara, CA last week. "A radical architecture shift is underway in this space, from proprietary to standards-based," he explained.  He pointed out several advantages to using Embedded Java for devices: Java is a proven and open standard. Java provides connectivity, encryption, location, and web services APIs. You don't have to focus on and keep reinventing the plumbing below the JVM. Abstracting the software from the hardware allows you to repeat your app across many devices. Abstracting the software from the hardware allows allows parallel development so you can get your app done more quickly. You already know Java (or you can hire lots of Java talent). Java is a full ecosystem, with Java Embedded plugins for IDEs like Eclipse and NetBeans. Java ME allows for in-field software upgrades. Suliman mentioned two ways developers can start using Java Embedded today:  Java ME Embedded Suite 7.0 Oracle Java Embedded Suite is a new packaged solution from Oracle (including Java DB, GlassFish for Embedded Suite, Jersey Web Services Framework, and Oracle Java SE Embedded 7 platform), created to provide value added services for collecting, managing, and transmitting data to embedded devices such as gateways and concentrators. Oracle Java ME Embedded 3.2 Oracle Java ME Embedded 3.2 is designed and optimized to meet the unique requirements of small embedded, low power devices such as micro-controllers and other resource-constrained hardware without screens or user interfaces. Think tiny. Really tiny. And think big.  Read more about Java Embedded at the Oracle Technology Network, and read The Java Source blog Java Embedded Releases from September.

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  • SQL SERVER – Fix: Error: 147 An aggregate may not appear in the WHERE clause unless it is in a subquery contained in a HAVING clause or a select list, and the column being aggregated is an outer reference

    - by pinaldave
    Everybody was beginner once and I always like to get involved in the questions from beginners. There is a big difference between the question from beginner and question from advanced user. I have noticed that if an advanced user gets an error, they usually need just a small hint to resolve the problem. However, when a beginner gets error he sometimes sits on the error for a long time as he/she has no idea about how to solve the problem as well have no idea regarding what is the capability of the product. I recently received a very novice level question. When I received the problem I quickly see how the user was stuck. When I replied him with the solution, he wrote a long email explaining how he was not able to solve the problem. He thanked multiple times in the email. This whole thing inspired me to write this quick blog post. I have modified the user’s question to match the code with AdventureWorks as well simplified so it contains the core content which I wanted to discuss. Problem Statement: Find all the details of SalesOrderHeaders for the latest ShipDate. He comes up with following T-SQL Query: SELECT * FROM [Sales].[SalesOrderHeader] WHERE ShipDate = MAX(ShipDate) GO When he executed above script it gave him following error: Msg 147, Level 15, State 1, Line 3 An aggregate may not appear in the WHERE clause unless it is in a subquery contained in a HAVING clause or a select list, and the column being aggregated is an outer reference. He was not able to resolve this problem, even though the solution was given in the query description itself. Due to lack of experience he came up with another version of above query based on the error message. SELECT * FROM [Sales].[SalesOrderHeader] HAVING ShipDate = MAX(ShipDate) GO When he ran above query it produced another error. Msg 8121, Level 16, State 1, Line 3 Column ‘Sales.SalesOrderHeader.ShipDate’ is invalid in the HAVING clause because it is not contained in either an aggregate function or the GROUP BY clause. What he wanted actually was the SalesOrderHeader all the Sales shipped on the last day. Based on the problem statement what the right solution is as following, which does not generate error. SELECT * FROM [Sales].[SalesOrderHeader] WHERE ShipDate = (SELECT MAX(ShipDate) FROM [Sales].[SalesOrderHeader]) Well, that’s it! Very simple. With SQL Server there are always multiple solution to a single problem. Is there any other solution available to the problem stated? Please share in the comment. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: PostADay, SQL, SQL Authority, SQL Error Messages, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology

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  • Technology to Prevent Multiple logins to the Same Computer

    - by Ngu Soon Hui
    OK, this is a similar question to this. Actually I am trying to prevent people from multiple login into one single computer and use my application simultaneously. This is because I want to stop them from buying one license, install it on a machine, and use certain remote desktop technologies to do multiple user login. I want to prevent them from violating the license agreement. Is there anyway that I can do in my application for this? Or is multiple login simultaneously is simply not possible?

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  • Qt Mobility 1.2 Technology Preview se focalise sur le support de MeeGo, en plus de supporter le Bluetooth et NFC

    Qt Mobility 1.2, la Technology Preview se focalise sur le support de MeeGo En plus de supporter le Bluetooth et NFC Mise à jour du 30/12/2010 par dourouc05 L'équipe de développement de Qt Mobility aimerait nous proposer ses avancées sur la version 1.2 - actuellement toujours en l'état de Technology Preview, rien n'est donc finalisé - ainsi que, comme cela était prévu pour la version 1.2, des paquets RPM pour tester sur MeeGo (en effet, l'objectif principal de cette version était le support de cette plateforme). Les sources sont aussi évidemment disponibles en paquets séparés, si vous souhaitez tester cette technology preview sous d'autres plateformes (pas de paquet disponib...

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  • What is the best cloud technology to use for MongoDB/GridFS database servers

    - by Nerian
    We are going to launch a service that will require between 1 and 2 GB for file storage per paid user. I am going to use GridFS for storing files. GridFS is a module for MongoDB that allows to store large files in de database. I am pondering the different options for storing the database. But since I am unexperienced at deployment and it is my first time with Mongodb I need your experience. Criteria: I want to spend my time developing my core business, that is, my own application. I am a Ruby on Rails developer. I do not like to mess with server configuration. Hence, I would like a fully managed hosting solution. But I would like to know about any other option, if you think it is worth it. It should be able to scale. Cloud style. Pay as you go. The lower the price, the better. So far I known of these services: https://mongohq.com/pricing https://mongomachine.com/pricing https://mongolab.com/about/pricing/ http://cloudcontrol.com/add-ons/mongodb/ And they seem to be OK for common needs, that is no file storage. But I am going to use GridFS, so the size matters. These services seems to scale, in price, quite poorly. MongoHQ: The larger plan max storage is 20 GB. Seems like a very little storage, for GridFS. MongoMachine: Flat price, 2.5$ per GB. I didn't found the limit. Seems like a good price, comparing the others. MongoLab: 3.984 GB max, which I don't think I will hit, so perfect. 8$ per GB, quite costly. CloudControl: The larger plan is 20 Gb. The custom service starts at 250€ plus some unspecified charge per GB. What is your experience with these services? Any downtimes? Other possibilities? Edit: Added meaning of GridFS

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  • Is ECC mandatory in SSD technology?

    - by Alexander Shcheblikin
    While shopping for an SSD I have noticed that some manufacturers promote their "Pro" models as the ones sporting ECC data protection. Those manufacturers do not mention ECC in their budget models descriptions. However, Wikipedia article on flash memory states that "NAND relies on ECC to compensate for bits that may spontaneously fail during normal device operation." So the question is does any SSD device use ECC behind the scenes for its normal operation and is that ECC "feature" just a marketing ploy?

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  • Technology mash: is this possible?

    - by Jon Story
    I'm in the process of setting up my own DNS+hosting on a couple of VPS and my home machines, mostly for academic/learning purposes, but also for convenient accessing of my files, hosting my personal websites, private git repositories etc. I've got a main web server with DNS, and a slave DNS server. I've also got a couple of machines at home doing file hosting, video streaming and all that fun stuff. I'm intending to use my VPS's to provide myself with a dynamic DNS system so that I can point mydomain.com at my DNS servers, with home.mydomain.com going into my home network via a raspberry pi. HOWEVER.... I've not got access to the network infrastructure at home (rented accommodation with managed internet), so I can't forward the ports on the router to my own machines. As such, I'm wondering if it's possible to route all the traffic via an SSH/HTTP tunnel through one of the VPS? My plan is to have the raspberry pi provide a VPN into my home network. The raspberry pi uses SSH to connect to the VPS, and the VPS forwards any traffic to home.mydomain.com via the tunnel to the raspberry pi. Is this even possible, and how do I go about it? I don't mind getting my hands dirty with coding and low level tools, I'm just not sure where to start or what the best way to go about it is.

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  • which virtualization technology is right for me?

    - by Chris
    I need a little help with this getting this sorted out. I want to setup a linux virtual server that I can use to run both sever and desktop systems. I want a linux system that is minimalist in nature as all the main os will be doing is acting as a hypervisor. The system I'm trying to setup will be running a file server, windows 7, ubuntu 10.04, windows xp and a firewall/gateway security system. All the client OS'es accessing and storing files on the file server. Also all network traffic will be routed through the gateway guest os. The file sever will need direct disk access while the other guests can run one disk images. All of this will be running on the same computer so I wont be romoting in to access the guests OS'es. Also if possible I would like to be able to use my triple head setup in the guest OS'es. I've looked at Xen, kvm and virtualbox but I don't know which is the best for me. I'm really debating between kvm and virtual box as kvm seem to support direct hardware access.

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  • Anticipating JavaOne 2012 – Number 17!

    - by Janice J. Heiss
    As I write this, JavaOne 2012 (September 30-October 4 in San Francisco, CA) is just over a week away -- the seventeenth JavaOne! I’ll resist the impulse to travel in memory back to the early days of JavaOne. But I will say that JavaOne is a little like your birthday or New Year’s in that it invites reflection, evaluation, and comparison. It’s a time when we take the temperature of Java and assess the world of information technology generally. At JavaOne, insight and information flow amongst Java developers like no other time of the year.This year, the status of Java seems more secure in the eyes of most Java developers who agree that Oracle is doing an acceptable job of stewarding the platform, and while the story is still in progress, few doubt that Oracle is engaging strongly with the Java community and wants to see Java thrive. From my perspective, the biggest news about Java is the growth of some 250 alternative languages for the JVM – from Groovy to Jython to JRuby to Scala to Clojure and on and on – offering both new opportunities and challenges. The JVM has proven itself to be unusually flexible, resulting in an embarrassment of riches in which, more and more, developers are challenged to find ways to optimally mix together several different languages on projects.    To the matter at hand -- I can say with confidence that Oracle is working hard to make each JavaOne better than the last – more interesting, more stimulating, more networking, and more fun! A great deal of thought and attention is being devoted to the task. To free up time for the 475 technical sessions/Birds of feather/Hands-on-Labs slots, the Java Strategy, Partner, and Technical keynotes will be held on Sunday September 30, beginning at 4:00 p.m.   Let’s not forget Java Embedded@JavaOne which is being held Wednesday, Oct. 3rd and Thursday, Oct. 4th at the Hotel Nikko. It will provide business decision makers, technical leaders, and ecosystem partners important information about Java Embedded technologies and new business opportunities.   This year's JavaOne theme is “Make the Future Java”. So come to JavaOne and make your future better by:--Choosing from 475 sessions given by the experts to improve your working knowledge and coding expertise --Networking with fellow developers in both casual and formal settings--Enjoying world-class entertainment--Delighting in one of the world’s great cities (my home town) Hope to see you there! Originally published on blogs.oracle.com/javaone.

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  • Summit 2014 Registration Is Open

    - by KemButller
    Attention Oracle (employees) Field Team and Oracle JD Edwards Partners REGISTRATION IS NOW OPEN for Oracle's 5th Annual JD Edwards Summit - Monday, January 27th through Friday, January 31st, 2014, in Broomfield, Colorado. The theme of this year's Summit is "Success Through Continued Innovation”.  Our goals are to update you on our current and future product roadmap, new products, selling strategies for new prospects, growing the footprint in our JD Edwards install base, as well as providing a venue for networking.  The JD Edwards Summit is to the selling and servicing community what COLLABORATE is to the user community.  This is a MUST ATTEND event if you recommend, sell, implement and/or support the JD Edwards product, whether you are new to JD Edwards or a seasoned pro, an executive, account executive, in presales or in consulting.  The Summit promises a content-rich and unique networking experience for all attendees. Highlights include:  Monday afternoon kicks off the Summit with a variety of workshops as well as an afternoon preview of the Sponsor Showcase.  Start your networking at the Summit kickoff party Monday evening. Tuesday morning features several informative keynotes in the Summit General Assembly followed by key messages delivered in Super Sessions in the afternoon, focused on each of the JD Edwards community audiences. The educational offerings continue on Wednesday and Thursday with over 90 breakout sessions on topics spanning technology, applications (core JD Edwards, Edge, Fusion), Sales, Presales and Implementation. Friday concludes with new workshops for the implementation community.A Attendees will be enriched with numerous opportunities to network with fellow partners and Oracle throughout the week.  Consider bringing your team and using this venue to hold your own organization kickoff meeting prior to or post Summit. Contact Sheila Ebbitt (Sheila.ebbitt@oracle-DOT-com) for further assistance with your planning.  Attendees will be charged a Summit fee of US$ 250. Online registration cut-off is January 17, 2014. All registration requests after that time will be processed on-site at the event with an attendee fee of US$ 500. Please contact Rene Chapman (rene.chapman@oracle-DOT-com) for information on sponsorship opportunities. For further details on the JD Edwards Summit including agenda, workshops, educational sessions, lodging,  sponsors and Summit registration, click here! Register now! This is going to be an awesome event! John Schiff Vice President JD Edwards Business Development 

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  • So Much Happening at Devoxx

    - by Tori Wieldt
    Devoxx, the premier Java conference in Europe, has been sold out for a while. The organizers (thanks Stephan and crew!) cap the attendance to make sure all attendees have a great experience, and that speaks volumes about their priorities. The speakers, hackathons, labs, and networking are all first class. The Oracle Technology Network will be there, and if you were smart/lucky enough to get a ticket, come find us and join the fun: IoT Hack Fest Build fun and creative Internet of Things (IoT) applications with Java Embedded, Raspberry Pi and Leap Motion on the University Days (Monday and Tuesday). Learn from top experts Yara & Vinicius Senger and Geert Bevin at two Raspberry Pi & Leap Motion hands-on labs and hacking sessions. Bring your computer. Training and equipment will be provided. Devoxx will also host an Internet of Things shop in the exhibition floor where attendees can purchase Arduino, Raspberry PI and Robot starter kits. Bring your IoT wish list! Video Interviews Yolande Poirier and I will be interviewing members of the Java Community in the back of the Expo hall on Wednesday and Thursday. Videos are posted on Parleys and YouTube/Java. We have a few slots left, so contact me (you can DM @Java) if you want to share your insights or cool new tip or trick with the rest of the developer community. (No commercials, no fluff. Keep it techie and keep it real.)  Oracle Keynote Wednesday morning Mark Reinhold, Chief Java Platform Architect, and Brian Goetz, Java Language Architect will provide an update on Java 8 and beyond. Oracle Booth Drop by the Oracle booth to see old and new friends.  We'll have Java in Action demos and the experts to explain them and answer your questions. We are raffling off Raspberry Pi's each day, so be sure to get your badged scanned. We'll have beer in the booth each evening. Look for @Java in her lab coat.  See you at Devoxx! 

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  • General type conversion without risking Exceptions

    - by Mongus Pong
    I am working on a control that can take a number of different datatypes (anything that implements IComparable). I need to be able to compare these with another variable passed in. If the main datatype is a DateTime, and I am passed a String, I need to attempt to convert the String to a DateTime to perform a Date comparison. if the String cannot be converted to a DateTime then do a String comparison. So I need a general way to attempt to convert from any type to any type. Easy enough, .Net provides us with the TypeConverter class. Now, the best I can work out to do to determine if the String can be converted to a DateTime is to use exceptions. If the ConvertFrom raises an exception, I know I cant do the conversion and have to do the string comparison. The following is the best I got : string theString = "99/12/2009"; DateTime theDate = new DateTime ( 2009, 11, 1 ); IComparable obj1 = theString as IComparable; IComparable obj2 = theDate as IComparable; try { TypeConverter converter = TypeDescriptor.GetConverter ( obj2.GetType () ); if ( converter.CanConvertFrom ( obj1.GetType () ) ) { Console.WriteLine ( obj2.CompareTo ( converter.ConvertFrom ( obj1 ) ) ); Console.WriteLine ( "Date comparison" ); } } catch ( FormatException ) { Console.WriteLine ( obj1.ToString ().CompareTo ( obj2.ToString () ) ); Console.WriteLine ( "String comparison" ); } Part of our standards at work state that : Exceptions should only be raised when an Exception situation - ie. an error is encountered. But this is not an exceptional situation. I need another way around it. Most variable types have a TryParse method which returns a boolean to allow you to determine if the conversion has succeeded or not. But there is no TryConvert method available to TypeConverter. CanConvertFrom only dermines if it is possible to convert between these types and doesnt consider the actual data to be converted. The IsValid method is also useless. Any ideas? EDIT I cannot use AS and IS. I do not know either data types at compile time. So I dont know what to As and Is to!!! EDIT Ok nailed the bastard. Its not as tidy as Marc Gravells, but it works (I hope). Thanks for the inpiration Marc. Will work on tidying it up when I get the time, but I've got a bit stack of bugfixes that I have to get on with. public static class CleanConverter { /// <summary> /// Stores the cache of all types that can be converted to all types. /// </summary> private static Dictionary<Type, Dictionary<Type, ConversionCache>> _Types = new Dictionary<Type, Dictionary<Type, ConversionCache>> (); /// <summary> /// Try parsing. /// </summary> /// <param name="s"></param> /// <param name="value"></param> /// <returns></returns> public static bool TryParse ( IComparable s, ref IComparable value ) { // First get the cached conversion method. Dictionary<Type, ConversionCache> type1Cache = null; ConversionCache type2Cache = null; if ( !_Types.ContainsKey ( s.GetType () ) ) { type1Cache = new Dictionary<Type, ConversionCache> (); _Types.Add ( s.GetType (), type1Cache ); } else { type1Cache = _Types[s.GetType ()]; } if ( !type1Cache.ContainsKey ( value.GetType () ) ) { // We havent converted this type before, so create a new conversion type2Cache = new ConversionCache ( s.GetType (), value.GetType () ); // Add to the cache type1Cache.Add ( value.GetType (), type2Cache ); } else { type2Cache = type1Cache[value.GetType ()]; } // Attempt the parse return type2Cache.TryParse ( s, ref value ); } /// <summary> /// Stores the method to convert from Type1 to Type2 /// </summary> internal class ConversionCache { internal bool TryParse ( IComparable s, ref IComparable value ) { if ( this._Method != null ) { // Invoke the cached TryParse method. object[] parameters = new object[] { s, value }; bool result = (bool)this._Method.Invoke ( null, parameters); if ( result ) value = parameters[1] as IComparable; return result; } else return false; } private MethodInfo _Method; internal ConversionCache ( Type type1, Type type2 ) { // Use reflection to get the TryParse method from it. this._Method = type2.GetMethod ( "TryParse", new Type[] { type1, type2.MakeByRefType () } ); } } }

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  • Vector of Object Pointers, general help and confusion

    - by Staypuft
    Have a homework assignment in which I'm supposed to create a vector of pointers to objects Later on down the load, I'll be using inheritance/polymorphism to extend the class to include fees for two-day delivery, next day air, etc. However, that is not my concern right now. The final goal of the current program is to just print out every object's content in the vector (name & address) and find it's shipping cost (weight*cost). My Trouble is not with the logic, I'm just confused on few points related to objects/pointers/vectors in general. But first my code. I basically cut out everything that does not mater right now, int main, will have user input, but right now I hard-coded two examples. #include <iostream> #include <string> #include <vector> using namespace std; class Package { public: Package(); //default constructor Package(string d_name, string d_add, string d_zip, string d_city, string d_state, double c, double w); double calculateCost(double, double); void Print(); ~Package(); private: string dest_name; string dest_address; string dest_zip; string dest_city; string dest_state; double weight; double cost; }; Package::Package() { cout<<"Constucting Package Object with default values: "<<endl; string dest_name=""; string dest_address=""; string dest_zip=""; string dest_city=""; string dest_state=""; double weight=0; double cost=0; } Package::Package(string d_name, string d_add, string d_zip, string d_city, string d_state, string r_name, string r_add, string r_zip, string r_city, string r_state, double w, double c){ cout<<"Constucting Package Object with user defined values: "<<endl; string dest_name=d_name; string dest_address=d_add; string dest_zip=d_zip; string dest_city=d_city; string dest_state=d_state; double weight=w; double cost=c; } Package::~Package() { cout<<"Deconstructing Package Object!"<<endl; delete Package; } double Package::calculateCost(double x, double y){ return x+y; } int main(){ double cost=0; vector<Package*> shipment; cout<<"Enter Shipping Cost: "<<endl; cin>>cost; shipment.push_back(new Package("tom r","123 thunder road", "90210", "Red Bank", "NJ", cost, 10.5)); shipment.push_back(new Package ("Harry Potter","10 Madison Avenue", "55555", "New York", "NY", cost, 32.3)); return 0; } So my questions are: I'm told I have to use a vector of Object Pointers, not Objects. Why? My assignment calls for it specifically, but I'm also told it won't work otherwise. Where should I be creating this vector? Should it be part of my Package Class? How do I go about adding objects into it then? Do I need a copy constructor? Why? What's the proper way to deconstruct my vector of object pointers? Any help would be appreciated. I've searched for a lot of related articles on here and I realize that my program will have memory leaks. Using one of the specialized ptrs from boost:: will not be available for me to use. Right now, I'm more concerned with getting the foundation of my program built. That way I can actually get down to the functionality I need to create. Thanks.

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  • SQL SERVER – Introduction to Extended Events – Finding Long Running Queries

    - by pinaldave
    The job of an SQL Consultant is very interesting as always. The month before, I was busy doing query optimization and performance tuning projects for our clients, and this month, I am busy delivering my performance in Microsoft SQL Server 2005/2008 Query Optimization and & Performance Tuning Course. I recently read white paper about Extended Event by SQL Server MVP Jonathan Kehayias. You can read the white paper here: Using SQL Server 2008 Extended Events. I also read another appealing chapter by Jonathan in the book, SQLAuthority Book Review – Professional SQL Server 2008 Internals and Troubleshooting. After reading these excellent notes by Jonathan, I decided to upgrade my course and include Extended Event as one of the modules. This week, I have delivered Extended Events session two times and attendees really liked the said course. They really think Extended Events is one of the most powerful tools available. Extended Events can do many things. I suggest that you read the white paper I mentioned to learn more about this tool. Instead of writing a long theory, I am going to write a very quick script for Extended Events. This event session captures all the longest running queries ever since the event session was started. One of the many advantages of the Extended Events is that it can be configured very easily and it is a robust method to collect necessary information in terms of troubleshooting. There are many targets where you can store the information, which include XML file target, which I really like. In the following Events, we are writing the details of the event at two locations: 1) Ringer Buffer; and 2) XML file. It is not necessary to write at both places, either of the two will do. -- Extended Event for finding *long running query* IF EXISTS(SELECT * FROM sys.server_event_sessions WHERE name='LongRunningQuery') DROP EVENT SESSION LongRunningQuery ON SERVER GO -- Create Event CREATE EVENT SESSION LongRunningQuery ON SERVER -- Add event to capture event ADD EVENT sqlserver.sql_statement_completed ( -- Add action - event property ACTION (sqlserver.sql_text, sqlserver.tsql_stack) -- Predicate - time 1000 milisecond WHERE sqlserver.sql_statement_completed.duration > 1000 ) -- Add target for capturing the data - XML File ADD TARGET package0.asynchronous_file_target( SET filename='c:\LongRunningQuery.xet', metadatafile='c:\LongRunningQuery.xem'), -- Add target for capturing the data - Ring Bugger ADD TARGET package0.ring_buffer (SET max_memory = 4096) WITH (max_dispatch_latency = 1 seconds) GO -- Enable Event ALTER EVENT SESSION LongRunningQuery ON SERVER STATE=START GO -- Run long query (longer than 1000 ms) SELECT * FROM AdventureWorks.Sales.SalesOrderDetail ORDER BY UnitPriceDiscount DESC GO -- Stop the event ALTER EVENT SESSION LongRunningQuery ON SERVER STATE=STOP GO -- Read the data from Ring Buffer SELECT CAST(dt.target_data AS XML) AS xmlLockData FROM sys.dm_xe_session_targets dt JOIN sys.dm_xe_sessions ds ON ds.Address = dt.event_session_address JOIN sys.server_event_sessions ss ON ds.Name = ss.Name WHERE dt.target_name = 'ring_buffer' AND ds.Name = 'LongRunningQuery' GO -- Read the data from XML File SELECT event_data_XML.value('(event/data[1])[1]','VARCHAR(100)') AS Database_ID, event_data_XML.value('(event/data[2])[1]','INT') AS OBJECT_ID, event_data_XML.value('(event/data[3])[1]','INT') AS object_type, event_data_XML.value('(event/data[4])[1]','INT') AS cpu, event_data_XML.value('(event/data[5])[1]','INT') AS duration, event_data_XML.value('(event/data[6])[1]','INT') AS reads, event_data_XML.value('(event/data[7])[1]','INT') AS writes, event_data_XML.value('(event/action[1])[1]','VARCHAR(512)') AS sql_text, event_data_XML.value('(event/action[2])[1]','VARCHAR(512)') AS tsql_stack, CAST(event_data_XML.value('(event/action[2])[1]','VARCHAR(512)') AS XML).value('(frame/@handle)[1]','VARCHAR(50)') AS handle FROM ( SELECT CAST(event_data AS XML) event_data_XML, * FROM sys.fn_xe_file_target_read_file ('c:\LongRunningQuery*.xet', 'c:\LongRunningQuery*.xem', NULL, NULL)) T GO -- Clean up. Drop the event DROP EVENT SESSION LongRunningQuery ON SERVER GO Just run the above query, afterwards you will find following result set. This result set contains the query that was running over 1000 ms. In our example, I used the XML file, and it does not reset when SQL services or computers restarts (if you are using DMV, it will reset when SQL services restarts). This event session can be very helpful for troubleshooting. Let me know if you want me to write more about Extended Events. I am totally fascinated with this feature, so I’m planning to acquire more knowledge about it so I can determine its other usages. 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, SQL Training, SQLServer, T SQL, Technology Tagged: SQL Extended Events

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  • SQL SERVER – Update Statistics are Sampled By Default

    - by pinaldave
    After reading my earlier post SQL SERVER – Create Primary Key with Specific Name when Creating Table on Statistics, I have received another question by a blog reader. The question is as follows: Question: Are the statistics sampled by default? Answer: Yes. The sampling rate can be specified by the user and it can be anywhere between a very low value to 100%. Let us do a small experiment to verify if the auto update on statistics is left on. Also, let’s examine a very large table that is created and statistics by default- whether the statistics are sampled or not. USE [AdventureWorks] GO -- Create Table CREATE TABLE [dbo].[StatsTest]( [ID] [int] IDENTITY(1,1) NOT NULL, [FirstName] [varchar](100) NULL, [LastName] [varchar](100) NULL, [City] [varchar](100) NULL, CONSTRAINT [PK_StatsTest] PRIMARY KEY CLUSTERED ([ID] ASC) ) ON [PRIMARY] GO -- Insert 1 Million Rows INSERT INTO [dbo].[StatsTest] (FirstName,LastName,City) SELECT TOP 1000000 'Bob', CASE WHEN ROW_NUMBER() OVER (ORDER BY a.name)%2 = 1 THEN 'Smith' ELSE 'Brown' END, CASE WHEN ROW_NUMBER() OVER (ORDER BY a.name)%10 = 1 THEN 'New York' WHEN ROW_NUMBER() OVER (ORDER BY a.name)%10 = 5 THEN 'San Marino' WHEN ROW_NUMBER() OVER (ORDER BY a.name)%10 = 3 THEN 'Los Angeles' ELSE 'Houston' END FROM sys.all_objects a CROSS JOIN sys.all_objects b GO -- Update the statistics UPDATE STATISTICS [dbo].[StatsTest] GO -- Shows the statistics DBCC SHOW_STATISTICS ("StatsTest"PK_StatsTest) GO -- Clean up DROP TABLE [dbo].[StatsTest] GO Now let us observe the result of the DBCC SHOW_STATISTICS. The result shows that Resultset is for sure sampling for a large dataset. The percentage of sampling is based on data distribution as well as the kind of data in the table. Before dropping the table, let us check first the size of the table. The size of the table is 35 MB. Now, let us run the above code with lesser number of the rows. USE [AdventureWorks] GO -- Create Table CREATE TABLE [dbo].[StatsTest]( [ID] [int] IDENTITY(1,1) NOT NULL, [FirstName] [varchar](100) NULL, [LastName] [varchar](100) NULL, [City] [varchar](100) NULL, CONSTRAINT [PK_StatsTest] PRIMARY KEY CLUSTERED ([ID] ASC) ) ON [PRIMARY] GO -- Insert 1 Hundred Thousand Rows INSERT INTO [dbo].[StatsTest] (FirstName,LastName,City) SELECT TOP 100000 'Bob', CASE WHEN ROW_NUMBER() OVER (ORDER BY a.name)%2 = 1 THEN 'Smith' ELSE 'Brown' END, CASE WHEN ROW_NUMBER() OVER (ORDER BY a.name)%10 = 1 THEN 'New York' WHEN ROW_NUMBER() OVER (ORDER BY a.name)%10 = 5 THEN 'San Marino' WHEN ROW_NUMBER() OVER (ORDER BY a.name)%10 = 3 THEN 'Los Angeles' ELSE 'Houston' END FROM sys.all_objects a CROSS JOIN sys.all_objects b GO -- Update the statistics UPDATE STATISTICS [dbo].[StatsTest] GO -- Shows the statistics DBCC SHOW_STATISTICS ("StatsTest"PK_StatsTest) GO -- Clean up DROP TABLE [dbo].[StatsTest] GO You can see that Rows Sampled is just the same as Rows of the table. In this case, the sample rate is 100%. Before dropping the table, let us also check the size of the table. The size of the table is less than 4 MB. Let us compare the Result set just for a valid reference. Test 1: Total Rows: 1000000, Rows Sampled: 255420, Size of the Table: 35.516 MB Test 2: Total Rows: 100000, Rows Sampled: 100000, Size of the Table: 3.555 MB The reason behind the sample in the Test1 is that the data space is larger than 8 MB, and therefore it uses more than 1024 data pages. If the data space is smaller than 8 MB and uses less than 1024 data pages, then the sampling does not happen. Sampling aids in reducing excessive data scan; however, sometimes it reduces the accuracy of the data as well. Please note that this is just a sample test and there is no way it can be claimed as a benchmark test. The result can be dissimilar on different machines. There are lots of other information can be included when talking about this subject. I will write detail post covering all the subject very soon. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, SQL, SQL Authority, SQL Index, SQL Optimization, SQL Performance, SQL Query, SQL Scripts, SQL Server, SQL Tips and Tricks, T SQL, Technology Tagged: SQL Statistics

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  • SQL SERVER – Disable Clustered Index and Data Insert

    - by pinaldave
    Earlier today I received following email. “Dear Pinal, [Removed unrelated content] We looked at your script and found out that in your script of disabling indexes, you have only included non-clustered index during the bulk insert and missed to disabled all the clustered index. Our DBA[name removed] has changed your script a bit and included all the clustered indexes. Since our application is not working. When DBA [name removed] tried to enable clustered indexes again he is facing error incorrect syntax error. We are in deep problem [word replaced] [Removed Identity of organization and few unrelated stuff ]“ I have replied to my client and helped them fixed the problem. What really came to my attention is the concept of disabling clustered index. Let us try to learn a lesson from this experience. In this case, there was no need to disable clustered index at all. I had done necessary work when I was called in to work on tuning project. I had removed unused indexes, created few optimal indexes and wrote a script to disable few selected high cost indexes when bulk insert (and similar) operations are performed. There was another script which rebuild all the indexes as well. The solution worked till they included clustered index in disabling the script. Clustered indexes are in fact original table (or heap) physically ordered (any more things – not scope of this article) according to one or more keys(columns). When clustered index is disabled data rows of the disabled clustered index cannot be accessed. This means there will be no insert possible. When non clustered indexes are disabled all the data related to physically deleted but the definition of the index is kept in the system. Due to the same reason even reorganization of the index is not possible till the clustered index (which was disabled) is rebuild. Now let us come to the second part of the question, regarding receiving the error when clustered index is ‘enabled’. This is very common question I receive on the blog. (The following statement is written keeping the syntax of T-SQL in mind) Clustered indexes can be disabled but can not be enabled, they have to rebuild. It is intuitive to think that something which we have ‘disabled’ can be ‘enabled’ but the syntax for the same is ‘rebuild’. This issue has been explained here: SQL SERVER – How to Enable Index – How to Disable Index – Incorrect syntax near ‘ENABLE’. Let us go over this example where inserting the data is not possible when clustered index is disabled. USE AdventureWorks GO -- Create Table CREATE TABLE [dbo].[TableName]( [ID] [int] NOT NULL, [FirstCol] [varchar](50) NULL, CONSTRAINT [PK_TableName] PRIMARY KEY CLUSTERED ([ID] ASC) ) GO -- Create Nonclustered Index CREATE UNIQUE NONCLUSTERED INDEX [IX_NonClustered_TableName] ON [dbo].[TableName] ([FirstCol] ASC) GO -- Populate Table INSERT INTO [dbo].[TableName] SELECT 1, 'First' UNION ALL SELECT 2, 'Second' UNION ALL SELECT 3, 'Third' GO -- Disable Nonclustered Index ALTER INDEX [IX_NonClustered_TableName] ON [dbo].[TableName] DISABLE GO -- Insert Data should work fine INSERT INTO [dbo].[TableName] SELECT 4, 'Fourth' UNION ALL SELECT 5, 'Fifth' GO -- Disable Clustered Index ALTER INDEX [PK_TableName] ON [dbo].[TableName] DISABLE GO -- Insert Data will fail INSERT INTO [dbo].[TableName] SELECT 6, 'Sixth' UNION ALL SELECT 7, 'Seventh' GO /* Error: Msg 8655, Level 16, State 1, Line 1 The query processor is unable to produce a plan because the index 'PK_TableName' on table or view 'TableName' is disabled. */ -- Reorganizing Index will also throw an error ALTER INDEX [PK_TableName] ON [dbo].[TableName] REORGANIZE GO /* Error: Msg 1973, Level 16, State 1, Line 1 Cannot perform the specified operation on disabled index 'PK_TableName' on table 'dbo.TableName'. */ -- Rebuliding should work fine ALTER INDEX [PK_TableName] ON [dbo].[TableName] REBUILD GO -- Insert Data should work fine INSERT INTO [dbo].[TableName] SELECT 6, 'Sixth' UNION ALL SELECT 7, 'Seventh' GO -- Clean Up DROP TABLE [dbo].[TableName] GO I hope this example is clear enough. There were few additional posts I had written years ago, I am listing them here. SQL SERVER – Enable and Disable Index Non Clustered Indexes Using T-SQL SQL SERVER – Enabling Clustered and Non-Clustered Indexes – Interesting Fact Reference : Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, SQL, SQL Authority, SQL Constraint and Keys, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology

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  • SQL SERVER – Server Side Paging in SQL Server 2011 Performance Comparison

    - by pinaldave
    Earlier, I have written about SQL SERVER – Server Side Paging in SQL Server 2011 – A Better Alternative. I got many emails asking for performance analysis of paging. Here is the quick analysis of it. The real challenge of paging is all the unnecessary IO reads from the database. Network traffic was one of the reasons why paging has become a very expensive operation. I have seen many legacy applications where a complete resultset is brought back to the application and paging has been done. As what you have read earlier, SQL Server 2011 offers a better alternative to an age-old solution. This article has been divided into two parts: Test 1: Performance Comparison of the Two Different Pages on SQL Server 2011 Method In this test, we will analyze the performance of the two different pages where one is at the beginning of the table and the other one is at its end. Test 2: Performance Comparison of the Two Different Pages Using CTE (Earlier Solution from SQL Server 2005/2008) and the New Method of SQL Server 2011 We will explore this in the next article. This article will tackle test 1 first. Test 1: Retrieving Page from two different locations of the table. Run the following T-SQL Script and compare the performance. SET STATISTICS IO ON; USE AdventureWorks2008R2 GO DECLARE @RowsPerPage INT = 10, @PageNumber INT = 5 SELECT * FROM Sales.SalesOrderDetail ORDER BY SalesOrderDetailID OFFSET @PageNumber*@RowsPerPage ROWS FETCH NEXT 10 ROWS ONLY GO USE AdventureWorks2008R2 GO DECLARE @RowsPerPage INT = 10, @PageNumber INT = 12100 SELECT * FROM Sales.SalesOrderDetail ORDER BY SalesOrderDetailID OFFSET @PageNumber*@RowsPerPage ROWS FETCH NEXT 10 ROWS ONLY GO You will notice that when we are reading the page from the beginning of the table, the database pages read are much lower than when the page is read from the end of the table. This is very interesting as when the the OFFSET changes, PAGE IO is increased or decreased. In the normal case of the search engine, people usually read it from the first few pages, which means that IO will be increased as we go further in the higher parts of navigation. I am really impressed because using the new method of SQL Server 2011,  PAGE IO will be much lower when the first few pages are searched in the navigation. Test 2: Retrieving Page from two different locations of the table and comparing to earlier versions. In this test, we will compare the queries of the Test 1 with the earlier solution via Common Table Expression (CTE) which we utilized in SQL Server 2005 and SQL Server 2008. Test 2 A : Page early in the table -- Test with pages early in table USE AdventureWorks2008R2 GO DECLARE @RowsPerPage INT = 10, @PageNumber INT = 5 ;WITH CTE_SalesOrderDetail AS ( SELECT *, ROW_NUMBER() OVER( ORDER BY SalesOrderDetailID) AS RowNumber FROM Sales.SalesOrderDetail PC) SELECT * FROM CTE_SalesOrderDetail WHERE RowNumber >= @PageNumber*@RowsPerPage+1 AND RowNumber <= (@PageNumber+1)*@RowsPerPage ORDER BY SalesOrderDetailID GO SET STATISTICS IO ON; USE AdventureWorks2008R2 GO DECLARE @RowsPerPage INT = 10, @PageNumber INT = 5 SELECT * FROM Sales.SalesOrderDetail ORDER BY SalesOrderDetailID OFFSET @PageNumber*@RowsPerPage ROWS FETCH NEXT 10 ROWS ONLY GO Test 2 B : Page later in the table -- Test with pages later in table USE AdventureWorks2008R2 GO DECLARE @RowsPerPage INT = 10, @PageNumber INT = 12100 ;WITH CTE_SalesOrderDetail AS ( SELECT *, ROW_NUMBER() OVER( ORDER BY SalesOrderDetailID) AS RowNumber FROM Sales.SalesOrderDetail PC) SELECT * FROM CTE_SalesOrderDetail WHERE RowNumber >= @PageNumber*@RowsPerPage+1 AND RowNumber <= (@PageNumber+1)*@RowsPerPage ORDER BY SalesOrderDetailID GO SET STATISTICS IO ON; USE AdventureWorks2008R2 GO DECLARE @RowsPerPage INT = 10, @PageNumber INT = 12100 SELECT * FROM Sales.SalesOrderDetail ORDER BY SalesOrderDetailID OFFSET @PageNumber*@RowsPerPage ROWS FETCH NEXT 10 ROWS ONLY GO From the resultset, it is very clear that in the earlier case, the pages read in the solution are always much higher than the new technique introduced in SQL Server 2011 even if we don’t retrieve all the data to the screen. If you carefully look at both the comparisons, the PAGE IO is much lesser in the case of the new technique introduced in SQL Server 2011 when we read the page from the beginning of the table and when we read it from the end. I consider this as a big improvement as paging is one of the most used features for the most part of the application. The solution introduced in SQL Server 2011 is very elegant because it also improves the performance of the query and, at large, the database. Reference : Pinal Dave (http://blog.SQLAuthority.com) Filed under: SQL, SQL Authority, SQL Optimization, SQL Performance, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology

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  • MySQL – Learning MySQL Online in 6 Hours – MySQL Fundamentals in 320 Minutes

    - by Pinal Dave
    MySQL is one of the most popular database language and I have been recently working with it a lot. Data have no barrier and every database have their own place. I have been working with MySQL for quite a while and just like SQL Server, I often find lots of people asking me if I have a tutorial which can teach them MySQL from the beginning. Here is the good news, I have written two different courses on MySQL Fundamentals, which is available online. The reason for writing two different courses was to keep the learning simple. Both of the courses are absolutely connected with other but designed if you watch either of the course independently you can watch them and learn without dependencies. However, if you ask me, I will suggest that you watch MySQL Fundamentals Part 1 course following with MySQL Fundamentals Part 2 course. Let us quickly explore outline of MySQL courses. MySQL Fundamental – 1 (157 minutes) MySQL is a popular choice of database for use in web applications, and is a central component of the widely used LAMP open source web application software stack. This course covers the fundamentals of MySQL, including how to install MySQL as well as written basic data retrieval and data modification queries. Introduction (duration 00:02:12) Installations and GUI Tools (duration 00:13:51) Fundamentals of RDBMS and Database Designs (duration 00:16:13) Introduction MYSQL Workbench (duration 00:31:51) Data Retrieval Techniques (duration 01:11:13) Data Modification Techniques (duration 00:20:41) Summary and Resources (duration 00:01:31) MySQL Fundamental – 2 (163 minutes) MySQL is a popular choice of database for use in web applications, and is a central component of the widely used LAMP open source web application software stack. In this course, which is part 2 of the Fundamentals of MySQL series, we explore more advanced topics such as stored procedures & user-defined functions, subqueries & joins, views and events & triggers. Introduction (duration 00:02:09) Joins, Unions and Subqueries (duration 01:03:56) MySQL Functions (duration 00:36:55) MySQL Views (duration 00:19:19) Stored Procedures and Stored Functions (duration 00:25:23) Triggers and Events (duration 00:13:41) Summary and Resources (duration 00:02:18) Note if you click on the link above and you do not see the play button to watch the course, you will have to login to the system and watch the course. I would like to throw a challenge to you – Can you watch both of the courses in a single day? If yes, once you are done watching the course on your Pluralsight Profile Page (here is my profile http://pluralsight.com/training/users/pinal-dave) you will get following badges. If you have already watched MySQL Fundamental Part 1, you can qualify by just watching MySQL Fundamental Part 2. Just send me the link to your profile and I will publish your name on this blog. For the first five people who send me email at Pinal at sqlauthority.com; I might have something cool as a giveaway as well. Watch the teaser of MySQL course. Reference: Pinal Dave (http://blog.sqlauthority.com)  Filed under: MySQL, PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology

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

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

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  • SQL SERVER – Introduction to Wait Stats and Wait Types – Wait Type – Day 1 of 28

    - by pinaldave
    I have been working a lot on Wait Stats and Wait Types recently. Last Year, I requested blog readers to send me their respective server’s wait stats. I appreciate their kind response as I have received  Wait stats from my readers. I took each of the results and carefully analyzed them. I provided necessary feedback to the person who sent me his wait stats and wait types. Based on the feedbacks I got, many of the readers have tuned their server. After a while I got further feedbacks on my recommendations and again, I collected wait stats. I recorded the wait stats and my recommendations and did further research. At some point at time, there were more than 10 different round trips of the recommendations and suggestions. Finally, after six month of working my hands on performance tuning, I have collected some real world wisdom because of this. Now I plan to share my findings with all of you over here. Before anything else, please note that all of these are based on my personal observations and opinions. They may or may not match the theory available at other places. Some of the suggestions may not match your situation. Remember, every server is different and consequently, there is more than one solution to a particular problem. However, this series is written with kept wait stats in mind. While I was working on various performance tuning consultations, I did many more things than just tuning wait stats. Today we will discuss how to capture the wait stats. I use the script diagnostic script created by my friend and SQL Server Expert Glenn Berry to collect wait stats. Here is the script to collect the wait stats: -- Isolate top waits for server instance since last restart or statistics clear WITH Waits AS (SELECT wait_type, wait_time_ms / 1000. AS wait_time_s, 100. * wait_time_ms / SUM(wait_time_ms) OVER() AS pct, ROW_NUMBER() OVER(ORDER BY wait_time_ms DESC) AS rn FROM sys.dm_os_wait_stats WHERE wait_type NOT IN ('CLR_SEMAPHORE','LAZYWRITER_SLEEP','RESOURCE_QUEUE','SLEEP_TASK' ,'SLEEP_SYSTEMTASK','SQLTRACE_BUFFER_FLUSH','WAITFOR', 'LOGMGR_QUEUE','CHECKPOINT_QUEUE' ,'REQUEST_FOR_DEADLOCK_SEARCH','XE_TIMER_EVENT','BROKER_TO_FLUSH','BROKER_TASK_STOP','CLR_MANUAL_EVENT' ,'CLR_AUTO_EVENT','DISPATCHER_QUEUE_SEMAPHORE', 'FT_IFTS_SCHEDULER_IDLE_WAIT' ,'XE_DISPATCHER_WAIT', 'XE_DISPATCHER_JOIN', 'SQLTRACE_INCREMENTAL_FLUSH_SLEEP')) SELECT W1.wait_type, CAST(W1.wait_time_s AS DECIMAL(12, 2)) AS wait_time_s, CAST(W1.pct AS DECIMAL(12, 2)) AS pct, CAST(SUM(W2.pct) AS DECIMAL(12, 2)) AS running_pct FROM Waits AS W1 INNER JOIN Waits AS W2 ON W2.rn <= W1.rn GROUP BY W1.rn, W1.wait_type, W1.wait_time_s, W1.pct HAVING SUM(W2.pct) - W1.pct < 99 OPTION (RECOMPILE); -- percentage threshold GO This script uses Dynamic Management View sys.dm_os_wait_stats to collect the wait stats. It omits the system-related wait stats which are not useful to diagnose performance-related bottleneck. Additionally, not OPTION (RECOMPILE) at the end of the DMV will ensure that every time the query runs, it retrieves new data and not the cached data. This dynamic management view collects all the information since the time when the SQL Server services have been restarted. You can also manually clear the wait stats using the following command: DBCC SQLPERF('sys.dm_os_wait_stats', CLEAR); Once the wait stats are collected, we can start analysis them and try to see what is causing any particular wait stats to achieve higher percentages than the others. Many waits stats are related to one another. When the CPU pressure is high, all the CPU-related wait stats show up on top. But when that is fixed, all the wait stats related to the CPU start showing reasonable percentages. It is difficult to have a sure solution, but there are good indications and good suggestions on how to solve this. I will keep this blog post updated as I will post more details about wait stats and how I reduce them. The reference to Book On Line is over here. Of course, I have selected February to run this Wait Stats series. I am already cheating by having the smallest month to run this series. :) Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: DMV, Pinal Dave, PostADay, SQL, SQL Authority, SQL Optimization, SQL Performance, SQL Query, SQL Scripts, SQL Server, SQL Tips and Tricks, SQL Wait Stats, SQL Wait Types, T SQL, Technology

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