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  • What is Linq?

    - by Aamir Hasan
    The way data can be retrieved in .NET. LINQ provides a uniform way to retrieve data from any object that implements the IEnumerable<T> interface. With LINQ, arrays, collections, relational data, and XML are all potential data sources. Why LINQ?With LINQ, you can use the same syntax to retrieve data from any data source:var query = from e in employeeswhere e.id == 1select e.nameThe middle level represents the three main parts of the LINQ project: LINQ to Objects is an API that provides methods that represent a set of standard query operators (SQOs) to retrieve data from any object whose class implements the IEnumerable<T> interface. These queries are performed against in-memory data.LINQ to ADO.NET augments SQOs to work against relational data. It is composed of three parts.LINQ to SQL (formerly DLinq) is use to query relational databases such as Microsoft SQL Server. LINQ to DataSet supports queries by using ADO.NET data sets and data tables. LINQ to Entities is a Microsoft ORM solution, allowing developers to use Entities (an ADO.NET 3.0 feature) to declaratively specify the structure of business objects and use LINQ to query them. LINQ to XML (formerly XLinq) not only augments SQOs but also includes a host of XML-specific features for XML document creation and queries. What You Need to Use LINQLINQ is a combination of extensions to .NET languages and class libraries that support them. To use it, you’ll need the following: Obviously LINQ, which is available from the new Microsoft .NET Framework 3.5 that you can download at http://go.microsoft.com/?linkid=7755937.You can speed up your application development time with LINQ using Visual Studio 2008, which offers visual tools such as LINQ to SQL designer and the Intellisense  support with LINQ’s syntax.Optionally, you can download the Visual C# 2008 Expression Edition tool at www.microsoft.com/vstudio/express/download. It is the free edition of Visual Studio 2008 and offers a lot of LINQ support such as Intellisense and LINQ to SQL designer. To use LINQ to ADO.NET, you need SQL

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  • Asp.NET ReportViewer “report execution has expired or cannot be found” error when using session state service or SQL Server session state

    - by dotneteer
    We encountered an error like: ReportServerException: The report execution x5pl2245iwvvq055khsxzlj5 has expired or cannot be found. (rsExecutionNotFound)]    Microsoft.Reporting.WebForms.ServerReportSoapProxy.OnSoapException(SoapException e) +72    Microsoft.Reporting.WebForms.Internal.Soap.ReportingServices2005.Execution.ProxyMethodInvocation.Execute(RSExecutionConnection connection, ProxyMethod`1 initialMethod, ProxyMethod`1 retryMethod) +428    Microsoft.Reporting.WebForms.Internal.Soap.ReportingServices2005.Execution.RSExecutionConnection.GetExecutionInfo() +133    Microsoft.Reporting.WebForms.ServerReport.EnsureExecutionSession() +197    Microsoft.Reporting.WebForms.ServerReport.LoadViewState(Object viewStateObj) +256    Microsoft.Reporting.WebForms.ServerReport..ctor(SerializationInfo info, StreamingContext context) +355 [TargetInvocationException: Exception has been thrown by the target of an invocation.]    System.RuntimeMethodHandle._SerializationInvoke(Object target, SignatureStruct&amp; declaringTypeSig, SerializationInfo info, StreamingContext context) +0    System.Reflection.RuntimeConstructorInfo.SerializationInvoke(Object target, SerializationInfo info, StreamingContext context) +108    System.Runtime.Serialization.ObjectManager.CompleteISerializableObject(Object obj, SerializationInfo info, StreamingContext context) +273    System.Runtime.Serialization.ObjectManager.FixupSpecialObject(ObjectHolder holder) +49    System.Runtime.Serialization.ObjectManager.DoFixups() +223    System.Runtime.Serialization.Formatters.Binary.ObjectReader.Deserialize(HeaderHandler handler, __BinaryParser serParser, Boolean fCheck, Boolean isCrossAppDomain, IMethodCallMessage methodCallMessage) +188    System.Runtime.Serialization.Formatters.Binary.BinaryFormatter.Deserialize(Stream serializationStream, HeaderHandler handler, Boolean fCheck, Boolean isCrossAppDomain, IMethodCallMessage methodCallMessage) +203    System.Web.Util.AltSerialization.ReadValueFromStream(BinaryReader reader) +788    System.Web.SessionState.SessionStateItemCollection.ReadValueFromStreamWithAssert() +55    System.Web.SessionState.SessionStateItemCollection.DeserializeItem(String name, Boolean check) +281    System.Web.SessionState.SessionStateItemCollection.DeserializeItem(Int32 index) +110    System.Web.SessionState.SessionStateItemCollection.get_Item(Int32 index) +17    System.Web.SessionState.HttpSessionStateContainer.get_Item(Int32 index) +13    System.Web.Util.AspCompatApplicationStep.OnPageStartSessionObjects() +71    System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +2065 This error occurs long after the report viewer page has closed. It occurs to any asp.net page in the application, rendering the entire application unusable until the user gets a new session. The cause of the problem is that the ReportViewer uses session state. When a page retrieves session from any out-of-state session, the session variable of type Microsoft.Reporting.WebForms.ReportHierarchy is deserialized from the session storage. The deserialization could cause the object to connect to the report server when the report is no longer available. The solution is simple but not pretty. We need to clean up the session variable when the report viewer page is closed. One way is to add some Javascript to the page to handle the window.onunload event. In the event handler, call a web service to clean up the session variable. The name of the session variable appears to be randomly generated. So we need to loop through the session variable to find a variable of the type Microsoft.Reporting.WebForms.ReportHierarchy. Microsoft has implemented pinging between the report viewer and the report server to keep the report alive on the server when the report viewer is up; I hope they will go one step further to take care of this problem.

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  • Slides and Samples for My TechEd / Microsoft BI Conference Talks

    - by plitwin
    I posted the slides and samples for my talks I delivered in New Orleans on June 8th at Microsoft TechEd and Business Intelligence Conference. They can be downloaded from Paul Litwin's Conference Downloads. #1 Creating Report Subscriptions with SQL Server 2008 Reporting Services at 8 AM on Tuesday. Room 241In this session, learn how to set up standard and data-driven subscriptions using Report Manager. We discuss creating file-share, email, and null subscriptions; and how to deal with potential issues with parameters and security. We also demonstrate a sophisticated Microsoft ASP.NET-based application that creates subscriptions by calling the SSRS Web Services API.  #2 ASP.NET MVC for Web Forms Programmers at 3:15 PM Tuesday. Room 391Are you comfortable creating ASP.NET Web Form applications but even a little curious about what all the fuss is about MVC and test-driven development? In this session, Web Form junkie Paul Litwin takes a critical look at the world of ASP.NET MVC, but not from any expert point of view. Instead, Paul shares his experience as a Web Form developer who decided to take a closer look at this radical new approach to ASP.NET development. Come hear what Paul learned and if he plans to employ ASP.NET MVC in his future ASP.NET applications.

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  • Macedonian Code Camp 2011

    - by hajan
    Autumn was filled with lot of conferences, events, speaking engagements and many interesting happenings in Skopje, Macedonia. First at October 20, I was speaking at Microsoft Vizija 9 on topic ASP.NET MVC3 and Razor. One week ago, November 15 I was speaking for first time on topic not related to web development (but still deployment of web apps was part of the demos) on topic “Cloud Computing – Windows Azure” at Microsoft BizSpark Bootcamp. The next event, which is the biggest event by the number of visitors and number of tracks is the Code Camp 2011 event. After we opened the registrations for the event, we sold out (free) 600 tickets in the first 15 hours! We all got astonished by the extremely big number of responses we’ve got… In this event, I can freely say that we expect about 700 attendees to come, and we already have 900+ registered. The event will be held at Saturday, 26 November 2011. At Code Camp 2011, I will speak on topic ASP.NET MVC Best Practices. There are many interesting things to say on this presentation, I will mainly focus on Tips, Tricks, Guidelines and other Practices that I have been using in real-life projects developed by using ASP.NET MVC Framework, with special focus on ASP.NET MVC3 and the next release, ASP.NET MVC4 Developer Preview. There are big number of known local and regional speakers, including 7 MVPs. You can find more info about this event at the official event website: http://codecamp.mkdot.net As for my session, if you have some interesting trick or good practice you have been using in your ASP.NET MVC projects, you can freely share it with me… If I find it interesting and if it’s not part of the current practices I have included for the presentation (I can’t tell you which ones for now… *secret* ;))… I will consider including it in the presentation. Stay tuned for more info soon… Regards, Hajan

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  • Fatal Execution Engine Error on the Windows2008 r2, IIS7.5

    - by user66524
    Hi Guys We are running some asp.net(3.5) applications on the Windows2008 r2, IIS7.5. Recently we got some event logs so difficult, we have not idea hope some guys can help. 1.EventID: 1334 (9-1-2011 8:41:57) Error message An error occurred during a process host idle check. Exception: System.AccessViolationException Message: Attempted to read or write protected memory. This is often an indication that other memory is corrupt. StackTrace: at System.Collections.Hashtable.GetEnumerator() at System.Web.Hosting.ApplicationManager.IsIdle() at System.Web.Hosting.ProcessHost.IsIdle() 2.EventID: 1023 (9-1-2011 19:44:02) Error message .NET Runtime version 2.0.50727.4952 - Fatal Execution Engine Error (742B851A) (80131506) 3.EventID: 1000 (9-1-2011 19:44:03) Error message Faulting application name: w3wp.exe, version: 7.5.7600.16385, time stamp: 0x4a5bcd2b Faulting module name: mscorwks.dll, version: 2.0.50727.4952, time stamp: 0x4bebd49a Exception code: 0xc0000005 Fault offset: 0x0000c262 Faulting process id: 0x%9 Faulting application start time: 0x%10 Faulting application path: %11 Faulting module path: %12 Report Id: %13 4.EventID: 5011 (9-1-2011 19:44:03) Error message A process serving application pool 'AppPoolName' suffered a fatal communication error with the Windows Process Activation Service. The process id was '2552'. The data field contains the error number. 5.some info: we got the memory.hdmp(234MB) and minidump.mdmp(19.2) from control panel action center but I donot know how to use that :(

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  • TDC: The Developer's Conference Day One

    - by Tori Wieldt
    The Developer's Conference (TDC) kicked off Wednesday in São Paulo, Brazil. With over 3000 developers in attendance over five days, it is the premier multi-community developer conference in Brazil, organized by Globalcode. Yara Senger, one of the organizers said, "We like to say multi-community rather than multi-technology because it is interesting and benefical when various communities get together. They learn so much from each other!" TDC includes tracks on Java and several other technologies, including SOA, Python, Ruby, mobile and digital TV. In the mobile track, developers who create a Java ME app will get a Nokia S40 phone!New this year at TDC is the Java University track, sponsored by Oracle.  It is aimed at university students and professionals who are new to Java. The lectures are introductory level, with an educational focus and practical exercises. The Java track and other tracks, such as SOA, mobile and Digital TV, are getting lots of help from the expertise of Brazilian JUGS members. Thanks to GoJava, JavaBahia, JavaNoroeste and SouJava!Carlos Fernando, one of the coordinators on the Digital TV track, said "My goal is to teach developers the basics of digital TV, and show them the tools used to build interactive TV applications." Fernando explained the concept of "the second screen:" that many people watch TV and have second smart device (tablet or smartphone) with them, and this creates many opportunities for developers. For example, while watching TV, a viewer can get extra content (interviews, behind the scenes) on their tablet. More interestingly, while watching their favorite TV show a viewer likes an outfit one of the actors is wearing, their smartphone can tell them where they can buy it nearby, or they can order it online immediately. Fernando exclaimed, "The opportunities for developers are nearly infinite in the area of digital TV!" At the TDC opening keynote, Debora Palermo, Oracle University country manager for Brazil, reminded attendees that Java is present in many devices, from simple to complex, and knowledge of this platform can open many doors in the labor market. She explained Oracle's Workforce Development Program (WDP), managed by Oracle University, which allows educational institutions to deliver Oracle training. WDP allows for easy and low-cost access to Oracle training in local communities across the world. "Oracle University is committed to creating the next generation of Java developers, and WDP can make that happen," Palermo said. As of March 2012, Oracle University is partnering with Globalcode to offer WDP. Students can earn official Oracle Course Certifications, a great way to learn Java.Brazilian developers that cannot attend TDC can watch live streaming.

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

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

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  • SQL SERVER – 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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  • SQL SERVER – Signal Wait Time Introduction with Simple Example – Wait Type – Day 2 of 28

    - by pinaldave
    In this post, let’s delve a bit more in depth regarding wait stats. The very first question: when do the wait stats occur? Here is the simple answer. When SQL Server is executing any task, and if for any reason it has to wait for resources to execute the task, this wait is recorded by SQL Server with the reason for the delay. Later on we can analyze these wait stats to understand the reason the task was delayed and maybe we can eliminate the wait for SQL Server. It is not always possible to remove the wait type 100%, but there are few suggestions that can help. Before we continue learning about wait types and wait stats, we need to understand three important milestones of the query life-cycle. Running - a query which is being executed on a CPU is called a running query. This query is responsible for CPU time. Runnable – a query which is ready to execute and waiting for its turn to run is called a runnable query. This query is responsible for Signal Wait time. (In other words, the query is ready to run but CPU is servicing another query). Suspended – a query which is waiting due to any reason (to know the reason, we are learning wait stats) to be converted to runnable is suspended query. This query is responsible for wait time. (In other words, this is the time we are trying to reduce). In simple words, query execution time is a summation of the query Executing CPU Time (Running) + Query Wait Time (Suspended) + Query Signal Wait Time (Runnable). Again, it may be possible a query goes to all these stats multiple times. Let us try to understand the whole thing with a simple analogy of a taxi and a passenger. Two friends, Tom and Danny, go to the mall together. When they leave the mall, they decide to take a taxi. Tom and Danny both stand in the line waiting for their turn to get into the taxi. This is the Signal Wait Time as they are ready to get into the taxi but the taxis are currently serving other customer and they have to wait for their turn. In other word they are in a runnable state. Now when it is their turn to get into the taxi, the taxi driver informs them he does not take credit cards and only cash is accepted. Neither Tom nor Danny have enough cash, they both cannot get into the vehicle. Tom waits outside in the queue and Danny goes to ATM to fetch the cash. During this time the taxi cannot wait, they have to let other passengers get into the taxi. As Tom and Danny both are outside in the queue, this is the Query Wait Time and they are in the suspended state. They cannot do anything till they get the cash. Once Danny gets the cash, they are both standing in the line again, creating one more Signal Wait Time. This time when their turn comes they can pay the taxi driver in cash and reach their destination. The time taken for the taxi to get from the mall to the destination is running time (CPU time) and the taxi is running. I hope this analogy is bit clear with the wait stats. You can check the Signalwait stats using following query of Glenn Berry. -- Signal Waits for instance SELECT CAST(100.0 * SUM(signal_wait_time_ms) / SUM (wait_time_ms) AS NUMERIC(20,2)) AS [%signal (cpu) waits], CAST(100.0 * SUM(wait_time_ms - signal_wait_time_ms) / SUM (wait_time_ms) AS NUMERIC(20,2)) AS [%resource waits] FROM sys.dm_os_wait_stats OPTION (RECOMPILE); Higher the Signal wait stats are not good for the system. Very high value indicates CPU pressure. In my experience, when systems are running smooth and without any glitch the Signal wait stat is lower than 20%. Again, this number can be debated (and it is from my experience and is not documented anywhere). In other words, lower is better and higher is not good for the system. In future articles we will discuss in detail the various wait types and wait stats and their resolution. Read all the post in the Wait Types and Queue series. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, PostADay, SQL, SQL Authority, SQL DMV, SQL Performance, SQL Query, SQL Scripts, SQL Server, SQL Tips and Tricks, SQL Wait Stats, SQL Wait Types, T SQL, Technology

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  • SQL SERVER – Single Wait Time Introduction with Simple Example – Wait Type – Day 2 of 28

    - by pinaldave
    In this post, let’s delve a bit more in depth regarding wait stats. The very first question: when do the wait stats occur? Here is the simple answer. When SQL Server is executing any task, and if for any reason it has to wait for resources to execute the task, this wait is recorded by SQL Server with the reason for the delay. Later on we can analyze these wait stats to understand the reason the task was delayed and maybe we can eliminate the wait for SQL Server. It is not always possible to remove the wait type 100%, but there are few suggestions that can help. Before we continue learning about wait types and wait stats, we need to understand three important milestones of the query life-cycle. Running - a query which is being executed on a CPU is called a running query. This query is responsible for CPU time. Runnable – a query which is ready to execute and waiting for its turn to run is called a runnable query. This query is responsible for Single Wait time. (In other words, the query is ready to run but CPU is servicing another query). Suspended – a query which is waiting due to any reason (to know the reason, we are learning wait stats) to be converted to runnable is suspended query. This query is responsible for wait time. (In other words, this is the time we are trying to reduce). In simple words, query execution time is a summation of the query Executing CPU Time (Running) + Query Wait Time (Suspended) + Query Single Wait Time (Runnable). Again, it may be possible a query goes to all these stats multiple times. Let us try to understand the whole thing with a simple analogy of a taxi and a passenger. Two friends, Tom and Danny, go to the mall together. When they leave the mall, they decide to take a taxi. Tom and Danny both stand in the line waiting for their turn to get into the taxi. This is the Signal Wait Time as they are ready to get into the taxi but the taxis are currently serving other customer and they have to wait for their turn. In other word they are in a runnable state. Now when it is their turn to get into the taxi, the taxi driver informs them he does not take credit cards and only cash is accepted. Neither Tom nor Danny have enough cash, they both cannot get into the vehicle. Tom waits outside in the queue and Danny goes to ATM to fetch the cash. During this time the taxi cannot wait, they have to let other passengers get into the taxi. As Tom and Danny both are outside in the queue, this is the Query Wait Time and they are in the suspended state. They cannot do anything till they get the cash. Once Danny gets the cash, they are both standing in the line again, creating one more Single Wait Time. This time when their turn comes they can pay the taxi driver in cash and reach their destination. The time taken for the taxi to get from the mall to the destination is running time (CPU time) and the taxi is running. I hope this analogy is bit clear with the wait stats. You can check the single wait stats using following query of Glenn Berry. -- Signal Waits for instance SELECT CAST(100.0 * SUM(signal_wait_time_ms) / SUM (wait_time_ms) AS NUMERIC(20,2)) AS [%signal (cpu) waits], CAST(100.0 * SUM(wait_time_ms - signal_wait_time_ms) / SUM (wait_time_ms) AS NUMERIC(20,2)) AS [%resource waits] FROM sys.dm_os_wait_stats OPTION (RECOMPILE); Higher the single wait stats are not good for the system. Very high value indicates CPU pressure. In my experience, when systems are running smooth and without any glitch the single wait stat is lower than 20%. Again, this number can be debated (and it is from my experience and is not documented anywhere). In other words, lower is better and higher is not good for the system. In future articles we will discuss in detail the various wait types and wait stats and their resolution. Read all the post in the Wait Types and Queue series. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, PostADay, SQL, SQL Authority, SQL DMV, SQL Performance, SQL Query, SQL Scripts, SQL Server, SQL Tips and Tricks, SQL Wait Stats, SQL Wait Types, T SQL, Technology

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  • ASP.NET request queue priority

    - by dan
    I'm on IIS 7 and .NET 4.0. My understanding is that IIS takes requests and passes them off to ASP.NET worker threads. If all the threads are in use, the request goes into a queue and is processed once a thread becomes available. If the queue goes over a certain size, all new requests get a 503 until there is room in the queue again. Is there a way to prioritize the order in which queued requests are served? For example, I have consumer traffic and infrastructure traffic coming to the same server. If there are no available threads, I'd like for the consumer requests to be served first, even if they have arrived after infrastructure requests. Basically I want to replace the request queue with a priority queue. Is this possible with IIS?

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  • iis7 .net webservice 404 error

    - by user11457
    I have a webservice /test/Service1.asmx in the same folder as a page /test/test.aspx. the page works fine but I get the message bellow for the services in the same location. I know the file is there and the url is correct, added the script module and managed handler as well. If anyone knows what I'm missing here I'd appreciate it Server Error in '/' Application. The resource cannot be found. Description: HTTP 404. The resource you are looking for (or one of its dependencies) could have been removed, had its name changed, or is temporarily unavailable. Please review the following URL and make sure that it is spelled correctly. Requested URL: /test/Service1.asmx Version Information: Microsoft .NET Framework Version:2.0.50727.4200; ASP.NET Version:2.0.50727.4016

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  • SQL SERVER – Best Reference – Wait Type – Day 27 of 28

    - by pinaldave
    I have great learning experience to write my article series on Extended Event. This was truly learning experience where I have learned way more than I would have learned otherwise. Besides my blog series there was excellent quality reference available on internet which one can use to learn this subject further. Here is the list of resources (in no particular order): sys.dm_os_wait_stats (Book OnLine) – This is excellent beginning point and official documentations on the wait types description. SQL Server Best Practices Article by Tom Davidson – I think this document goes without saying the BEST reference available on this subject. Performance Tuning with Wait Statistics by Joe Sack – One of the best slide deck available on this subject. It covers many real world scenarios. Wait statistics, or please tell me where it hurts by Paul Randal – Notes from real world from SQL Server Skilled Master Paul Randal. The SQL Server Wait Type Repository… by Bob Ward – A thorough article on wait types and its resolution. A MUST read. Tracking Session and Statement Level Waits by by Jonathan Kehayias – A unique article on the subject where wait stats and extended events are together. Wait Stats Introductory References By Jimmy May – Excellent collection of the reference links. Great Resource On SQL Server Wait Types by Glenn Berry – A perfect DMV to find top wait stats. Performance Blog by Idera – In depth article on top of the wait statistics in community. I have listed all the reference I have found in no particular order. If I have missed any good reference, please leave a comment and I will add the reference in the list. Read all the post in the Wait Types and Queue series. Reference: Pinal Dave (http://blog.SQLAuthority.com) Tracking Session and Statement Level Waits Filed under: Pinal Dave, PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, SQL Wait Stats, SQL Wait Types, T SQL, Technology

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  • HP Loadrunner failed to start .NET Diagnostics probe

    - by Johnbo
    I've got a HP Diagnostics Server (commander mode) installed in the same PC where HP Loadrunner is. I've installed the .NET probe in the web application server. When I navigate localhost:2006/registrar/health I can see the CommandingServer and three instances of the probe, all in green and connected. Then, when in LoadRunner controller I enable Diagnostics, select the probe and start the scenario, I get the next error: Failed to start J2EE/.NET Diagnostics run. (Facade error: Unable to send 'startRun' notification to probe MyAgent.1347615505142149) I've looked at the firewall logs and the rule that lets the server send commands to the probes has been matched three times. What else could it be what doesn't let me start the probe?

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  • SQL SERVER – FT_IFTS_SCHEDULER_IDLE_WAIT – Full Text – Wait Type – Day 13 of 28

    - by pinaldave
    In the last few days during this series, I got many question about this Wait type. It would be great if you read my original related wait stats query in the first post because I have filtered it out in WHERE clause. However, I still get questions about this being one of the most wait types they encounter. The truth is, this is a background task processing and it really does not matter and it should be filtered out. There are many new Wait types related to Full Text Search that are introduced in SQL Server 2008. If you run the following query, you will be able to find them in the list. Currently there is not enough information for all of them available on BOL or any other place. But don’t worry; I will write an in-depth article when I learn more about them. SELECT * FROM sys.dm_os_wait_stats WHERE wait_type LIKE 'FT_%' The result set will contain following rows. FT_RESTART_CRAWL FT_METADATA_MUTEX FT_IFTSHC_MUTEX FT_IFTSISM_MUTEX FT_IFTS_RWLOCK FT_COMPROWSET_RWLOCK FT_MASTER_MERGE FT_IFTS_SCHEDULER_IDLE_WAIT We have understood so far that there is not much information available. But the problem is when you have this Wait type, what should you do?  The answer is to filter them out for the moment (i.e, do not pay attention on them) and focus on other pressing issues in wait stats or performance tuning. Here are two of my informal suggestions, which are totally independent from wait stats: Turn off the Full Text Search service in your system if you are  not necessarily using it on your server. Learn proper Full Text Search methodology. You can get Michael Coles’ book: Pro Full-Text Search in SQL Server 2008. Now I invite you to speak out your suggestions or any input regarding Full Text-related best practices and wait stats issue. Please leave a comment. Note: The information presented here is from my experience and there is no way that I claim it to be accurate. I suggest reading Book OnLine for further clarification. All the discussions of Wait Stats in this blog are generic and vary from system to system. It is recommended that you test this on a development server before implementing it to a production server. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, PostADay, SQL, SQL Authority, SQL Query, SQL Scripts, SQL Server, SQL Tips and Tricks, SQL Wait Stats, SQL Wait Types, T SQL, Technology

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  • SQL SERVER – PAGEIOLATCH_DT, PAGEIOLATCH_EX, PAGEIOLATCH_KP, PAGEIOLATCH_SH, PAGEIOLATCH_UP – Wait Type – Day 9 of 28

    - by pinaldave
    It is very easy to say that you replace your hardware as that is not up to the mark. In reality, it is very difficult to implement. It is really hard to convince an infrastructure team to change any hardware because they are not performing at their best. I had a nightmare related to this issue in a deal with an infrastructure team as I suggested that they replace their faulty hardware. This is because they were initially not accepting the fact that it is the fault of their hardware. But it is really easy to say “Trust me, I am correct”, while it is equally important that you put some logical reasoning along with this statement. PAGEIOLATCH_XX is such a kind of those wait stats that we would directly like to blame on the underlying subsystem. Of course, most of the time, it is correct – the underlying subsystem is usually the problem. From Book On-Line: PAGEIOLATCH_DT Occurs when a task is waiting on a latch for a buffer that is in an I/O request. The latch request is in Destroy mode. Long waits may indicate problems with the disk subsystem. PAGEIOLATCH_EX Occurs when a task is waiting on a latch for a buffer that is in an I/O request. The latch request is in Exclusive mode. Long waits may indicate problems with the disk subsystem. PAGEIOLATCH_KP Occurs when a task is waiting on a latch for a buffer that is in an I/O request. The latch request is in Keep mode. Long waits may indicate problems with the disk subsystem. PAGEIOLATCH_SH Occurs when a task is waiting on a latch for a buffer that is in an I/O request. The latch request is in Shared mode. Long waits may indicate problems with the disk subsystem. PAGEIOLATCH_UP Occurs when a task is waiting on a latch for a buffer that is in an I/O request. The latch request is in Update mode. Long waits may indicate problems with the disk subsystem. PAGEIOLATCH_XX Explanation: Simply put, this particular wait type occurs when any of the tasks is waiting for data from the disk to move to the buffer cache. ReducingPAGEIOLATCH_XX wait: Just like any other wait type, this is again a very challenging and interesting subject to resolve. Here are a few things you can experiment on: Improve your IO subsystem speed (read the first paragraph of this article, if you have not read it, I repeat that it is easy to say a step like this than to actually implement or do it). This type of wait stats can also happen due to memory pressure or any other memory issues. Putting aside the issue of a faulty IO subsystem, this wait type warrants proper analysis of the memory counters. If due to any reasons, the memory is not optimal and unable to receive the IO data. This situation can create this kind of wait type. Proper placing of files is very important. We should check file system for the proper placement of files – LDF and MDF on separate drive, TempDB on separate drive, hot spot tables on separate filegroup (and on separate disk), etc. Check the File Statistics and see if there is higher IO Read and IO Write Stall SQL SERVER – Get File Statistics Using fn_virtualfilestats. It is very possible that there are no proper indexes on the system and there are lots of table scans and heap scans. Creating proper index can reduce the IO bandwidth considerably. If SQL Server can use appropriate cover index instead of clustered index, it can significantly reduce lots of CPU, Memory and IO (considering cover index has much lesser columns than cluster table and all other it depends conditions). You can refer to the two articles’ links below previously written by me that talk about how to optimize indexes. Create Missing Indexes Drop Unused Indexes Updating statistics can help the Query Optimizer to render optimal plan, which can only be either directly or indirectly. I have seen that updating statistics with full scan (again, if your database is huge and you cannot do this – never mind!) can provide optimal information to SQL Server optimizer leading to efficient plan. Checking Memory Related Perfmon Counters SQLServer: Memory Manager\Memory Grants Pending (Consistent higher value than 0-2) SQLServer: Memory Manager\Memory Grants Outstanding (Consistent higher value, Benchmark) SQLServer: Buffer Manager\Buffer Hit Cache Ratio (Higher is better, greater than 90% for usually smooth running system) SQLServer: Buffer Manager\Page Life Expectancy (Consistent lower value than 300 seconds) Memory: Available Mbytes (Information only) Memory: Page Faults/sec (Benchmark only) Memory: Pages/sec (Benchmark only) Checking Disk Related Perfmon Counters Average Disk sec/Read (Consistent higher value than 4-8 millisecond is not good) Average Disk sec/Write (Consistent higher value than 4-8 millisecond is not good) Average Disk Read/Write Queue Length (Consistent higher value than benchmark is not good) 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 SERVER – WRITELOG – Wait Type – Day 17 of 28

    - by pinaldave
    WRITELOG is one of the most interesting wait types. So far we have seen a lot of different wait types, but this log type is associated with log file which makes it interesting to deal with. From Book On-Line: WRITELOG Occurs while waiting for a log flush to complete. Common operations that cause log flushes are checkpoints and transaction commits. WRITELOG Explanation: This wait type is usually seen in the heavy transactional database. When data is modified, it is written both on the log cache and buffer cache. This wait type occurs when data in the log cache is flushing to the disk. During this time, the session has to wait due to WRITELOG. I have recently seen this wait type’s persistence at my client’s place, where one of the long-running transactions was stopped by the user causing it to roll back. In the future, I will see if I could re-create this situation once again on my machine to validate the relation. Reducing WRITELOG wait: There are several suggestions to reduce this wait stats: Move Transaction Log to Separate Disk from mdf and other files. Avoid cursor-like coding methodology and frequent committing of statements. Find the most active file based on IO stall time based on the script written over here. You can also use fn_virtualfilestats to find IO-related issues using the script mentioned over here. Check the IO-related counters (PhysicalDisk:Avg.Disk Queue Length, PhysicalDisk:Disk Read Bytes/sec and PhysicalDisk :Disk Write Bytes/sec) for additional details. Read about them over here. There are two excellent resources by Paul Randal, I suggest you understand the subject from those videos. The links to videos are here and here. Note: The information presented here is from my experience and there is no way that I claim it to be accurate. I suggest reading Book OnLine for further clarification. All the discussion of Wait Stats in this blog is generic and varies from system to system. It is recommended that you test this on a development server before implementing it to a production server. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, PostADay, SQL, SQL Authority, SQL Query, SQL Scripts, SQL Server, SQL Tips and Tricks, SQL Wait Stats, SQL Wait Types, T SQL, Technology

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  • SQL SERVER – 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 SERVER – LCK_M_XXX – Wait Type – Day 15 of 28

    - by pinaldave
    Locking is a mechanism used by the SQL Server Database Engine to synchronize access by multiple users to the same piece of data, at the same time. In simpler words, it maintains the integrity of data by protecting (or preventing) access to the database object. From Book On-Line: LCK_M_BU Occurs when a task is waiting to acquire a Bulk Update (BU) lock. LCK_M_IS Occurs when a task is waiting to acquire an Intent Shared (IS) lock. LCK_M_IU Occurs when a task is waiting to acquire an Intent Update (IU) lock. LCK_M_IX Occurs when a task is waiting to acquire an Intent Exclusive (IX) lock. LCK_M_S Occurs when a task is waiting to acquire a Shared lock. LCK_M_SCH_M Occurs when a task is waiting to acquire a Schema Modify lock. LCK_M_SCH_S Occurs when a task is waiting to acquire a Schema Share lock. LCK_M_SIU Occurs when a task is waiting to acquire a Shared With Intent Update lock. LCK_M_SIX Occurs when a task is waiting to acquire a Shared With Intent Exclusive lock. LCK_M_U Occurs when a task is waiting to acquire an Update lock. LCK_M_UIX Occurs when a task is waiting to acquire an Update With Intent Exclusive lock. LCK_M_X Occurs when a task is waiting to acquire an Exclusive lock. LCK_M_XXX Explanation: I think the explanation of this wait type is the simplest. When any task is waiting to acquire lock on any resource, this particular wait type occurs. The common reason for the task to be waiting to put lock on the resource is that the resource is already locked and some other operations may be going on within it. This wait also indicates that resources are not available or are occupied at the moment due to some reasons. There is a good chance that the waiting queries start to time out if this wait type is very high. Client application may degrade the performance as well. You can use various methods to find blocking queries: EXEC sp_who2 SQL SERVER – Quickest Way to Identify Blocking Query and Resolution – Dirty Solution DMV – sys.dm_tran_locks DMV – sys.dm_os_waiting_tasks Reducing LCK_M_XXX wait: Check the Explicit Transactions. If transactions are very long, this wait type can start building up because of other waiting transactions. Keep the transactions small. Serialization Isolation can build up this wait type. If that is an acceptable isolation for your business, this wait type may be natural. The default isolation of SQL Server is ‘Read Committed’. One of my clients has changed their isolation to “Read Uncommitted”. I strongly discourage the use of this because this will probably lead to having lots of dirty data in the database. Identify blocking queries mentioned using various methods described above, and then optimize them. Partition can be one of the options to consider because this will allow transactions to execute concurrently on different partitions. If there are runaway queries, use timeout. (Please discuss this solution with your database architect first as timeout can work against you). Check if there is no memory and IO-related issue using the following counters: Checking Memory Related Perfmon Counters SQLServer: Memory Manager\Memory Grants Pending (Consistent higher value than 0-2) SQLServer: Memory Manager\Memory Grants Outstanding (Consistent higher value, Benchmark) SQLServer: Buffer Manager\Buffer Hit Cache Ratio (Higher is better, greater than 90% for usually smooth running system) SQLServer: Buffer Manager\Page Life Expectancy (Consistent lower value than 300 seconds) Memory: Available Mbytes (Information only) Memory: Page Faults/sec (Benchmark only) Memory: Pages/sec (Benchmark only) Checking Disk Related Perfmon Counters Average Disk sec/Read (Consistent higher value than 4-8 millisecond is not good) Average Disk sec/Write (Consistent higher value than 4-8 millisecond is not good) Average Disk Read/Write Queue Length (Consistent higher value than benchmark is not good) Read all the post in the Wait Types and Queue series. Note: The information presented here is from my experience and there is no way that I claim it to be accurate. I suggest reading Book OnLine for further clarification. All the discussion of Wait Stats in this blog is generic and varies from system to system. It is recommended that you test this on a development server before implementing it to a production server. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, SQL Wait Stats, SQL Wait Types, T SQL, Technology

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  • SQL SERVER – Interview Questions and Answers – Frequently Asked Questions – Introduction – Day 1 of 31

    - by pinaldave
    List of all the Interview Questions and Answers Series blogs Posts covering interview questions and answers always make for interesting reading.  Some people like the subject for their helpful hints and thought provoking subject, and others dislike these posts because they feel it is nothing more than cheating.  I’d like to discuss the pros and cons of a Question and Answer format here. Interview Questions and Answers are Helpful Just like blog posts, books, and articles, interview Question and Answer discussions are learning material.  The popular Dummy’s books or Idiots Guides are not only for “dummies,” but can help everyone relearn the fundamentals.  Question and Answer discussions can serve the same purpose.  You could call this SQL Server Fundamentals or SQL Server 101. I have administrated hundreds of interviews during my career and I have noticed that sometimes an interviewee with several years of experience lacks an understanding of the fundamentals.  These individuals have been in the industry for so long, usually working on a very specific project, that the ABCs of the business have slipped their mind. Or, when a college graduate is looking to get into the industry, he is not expected to have experience since he is just graduated. However, the new grad is expected to have an understanding of fundamentals and theory.  Sometimes after the stress of final exams and graduation, it can be difficult to remember the correct answers to interview questions, though. An interview Question and Answer discussion can be very helpful to both these individuals.  It is simply a way to go back over the building blocks of a topic.  Many times a simple review like this will help “jog” your memory, and all those previously-memorized facts will come flooding back to you.  It is not a way to re-learn a topic, but a way to remind yourself of what you already know. A Question and Answer discussion can also be a way to go over old topics in a more interesting manner.  Especially if you have been working in the industry, or taking lots of classes on the topic, everything you read can sound like a repeat of what you already know.  Going over a topic in a new format can make the material seem fresh and interesting.  And an interested mind will be more engaged and remember more in the end. Interview Questions and Answers are Harmful A common argument against a Question and Answer discussion is that it will give someone a “cheat sheet.” A new guy with relatively little experience can read the interview questions and answers, and then memorize them. When an interviewer asks him the same questions, he will repeat the answers and get the job. Honestly, is he good hire because he memorized the interview questions? Wouldn’t it be better for the interviewer to hire someone with actual experience?  The answer is not as easy as it seems – there are many different factors to be considered. If the interviewer is asking fundamentals-related questions only, he gets the answers he wants to hear, and then hires this first candidate – there is a good chance that he is hiring based on personality rather than experience.  If the interviewer is smart he will ask deeper questions, have more than one person on the interview team, and interview a variety of candidates.  If one interviewee happens to memorize some answers, it usually doesn’t mean he will automatically get the job at the expense of more qualified candidates. Another argument against interview Question and Answers is that it will give candidates a false sense of confidence, and that they will appear more qualified than they are. Well, if that is true, it will not last after the first interview when the candidate is asked difficult questions and he cannot find the answers in the list of interview Questions and Answers.  Besides, confidence is one of the best things to walk into an interview with! In today’s competitive job market, there are often hundreds of candidates applying for the same position.  With so many applicants to choose from, interviewers must make decisions about who to call back and who to hire based on their gut feeling.  One drawback to reading an interview Question and Answer article is that you might sound very boring in your interview – saying the same thing as every single candidate, and parroting answers that sound like someone else wrote them for you – because they did.  However, it is definitely better to go to an interview prepared, just make sure that you give a lot of thought to your answers to make them sound like your own voice.  Remember that you will be hired based on your skills as well as your personality, so don’t think that having all the right answers will make get you hired.  A good interviewee will be prepared, confident, and know how to stand out. My Opinion A list of interview Questions and Answers is really helpful as a refresher or for beginners. To really ace an interview, one needs to have real-world, hands-on experience with SQL Server as well. Interview questions just serve as a starter or easy read for experienced professionals. When I have to learn new technology, I often search online for interview questions and get an idea about the breadth and depth of the technology. Next Action I am going to write about interview Questions and Answers for next 30 days. I have previously written a series of interview questions and answers; now I have re-written them keeping the latest version of SQL Server and current industry progress in mind. If you have faced interesting interview questions or situations, please write to me and I will publish them as a guest post. If you want me to add few more details, leave a comment and I will make sure that I do my best to accommodate. Tomorrow we will start the interview Questions and Answers series, with a few interesting stories, best practices and guest posts. We will have a prize give-away and other awards when the series ends. List of all the Interview Questions and Answers Series blogs Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, PostADay, SQL, SQL Authority, SQL Interview Questions and Answers, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology

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  • Building Great-Looking, Usable Apps: A two-day workshop applying Oracle’s best UX practices in ADF

    - by mvaughan
    By Misha Vaughan, Oracle Applications User ExperienceI have been with Oracle for more than 12 years. It is a company that has granted me extraordinary creative freedom to help deliver compelling experiences for customers.I am beyond proud to talk about one of the experiences we just took for a test drive. Recently, we delivered a first-of-its-kind, three-team collaboration, train-the-trainer event in Reading, U.K., on building great-looking, usable apps based on Oracle Fusion Applications -- using the ADF tool kit. A new kind of workshopKevin Li, Platform Product Director, asked the Oracle Applications User Experience VP, Jeremy Ashley, if the team had anything to help partners and customers build applications that looked like Fusion. He was receiving this request from European partners and customers.Some quick conversations ensued, and the idea for the workshop was born: We would conduct an experiment.  We would work with feedback from the key Platform Technology Solutions (PTS) trainers under Andre Pavanello, Director, Platform Technology Solutions, in Europe, Middle East, and Africa. We would partner with the ADF team lead by Grant Ronald, Director of Product Management, title> and leverage the Applications UX expertise in Ashley’s team.The goal: Create a pilot workshop that in two days would explain to an ADF developer how to leverage the next-generation user experience best-practices developed for Fusion Apps. Why? Customers who need integrations with Oracle Fusion Applications, who are looking for custom applications that need to co-exist with Fusion, or who quite simply want a next-generation design for a custom app, need their solutions to reflect the next-generation research and design.Building an event for an ADF developerThe biggest hurdle was figuring out where to start.  How far into user experience country do you take an ADF developer? How far into ADF do you need to go if you are a UX professional?After some time in the UX kitchen, the workshop recipe looked like this: Mix equal parts: Fusion user experience design principles and functional design patterns The art and science behind UX How to wireframe designs that you can build in Fusion How to translate those designs into an ADF application Ultan O’Broin, Director of Global User Experience, explaining the trouble ticket wireframe design exerciseLynn Munsinger, Senior Group Product Manager, explaining the follow-on trouble ticket ADF coding exercise For spice, add:•    Debra Lilley, Fujitsu and ACE director, showcasing some of the latest ADF design work in the new face of Fusion Applications •    Partner show-and-tell of example apps they have built with FMW and ADF that are dynamic, beautiful, and interactive.Debra Lilley, Oracle ACE Director and Fujitsu Fusion Champion on the new face of Fusion built with ADF and Fusion extensibility with composers as a window into “the possible”?The taste testThis first go-round of the workshop was aimed squarely at ADF developers and partners.  We were privileged to have participation and feedback from:•    Sten Vesterli, Scott/Tiger S. A., Denmark•    John Sim, Fishbowl Solutions, UK•    Josef Huber, Primus Delphi Group, Munich•    Thaddaus Weindl, Primus Delphi, Group , Munich•    Praveen Pillalamarri, EiS Technologies, Bangalore•    Balaji Kamepalli, EiS Technologies, Bangalore•    Plinio Arbizu, Services & Processes Solutions S. A., Mexico•    Yannick Ongena, infoMENTUM, UK•    Jakub Ciszek, infoMENTUM, UK•    Mauro Flores, infoMENTUM, UK•    Matteo Formica, infoMENTUM, UKRichard Bingham, Oracle, Mauro Flores and Matteo Formica, infoMENTUMWhy is this so exciting?  Oracle has invested heavily in the research and development of the Oracle Fusion Applications user experience. This investment has been and continues to be applied across the product lines. Now, we finally get to teach customers and partners how to take advantage of this investment for custom solutions.This event was a pilot to test-drive the content, as well as a train-the-trainer event that our EMEA colleagues will be using with partners who want to build with Fusion Apps design patterns.What did attendees think?"I liked most the science stuff, like eye-tracking, design patterns and best-practice (color, contrast),” Josef Huber said. “It was a very good introduction to UI design, and most developers and project managers are very bad in that.  So this course would be good for all developers and even project managers." Team Anonymous: John Sim, Fishbowl Solutions, Flavius Sana, Oracle, Josef Huber, infoMENTUM, Mireille Duroussaud, Oracle. Winners of the wireframing design exercise.  Sten Vesterli, of Scott/Tiger, said he attended to learn techniques he could use in his own projects. He wants to ensure that his applications better meet the needs of his users, and he said sessions during the workshop on user interface design and wireframing were most useful to him.  “Go to this event to learn the art and science of good user interfaces from people who really know how to do it,” he said.Sten Vesterli, Scott/Tiger, Angelo Santagata, Oracle Plinio Arbizu said the workshop fulfilled his goals, thanks to the recommendations given in how to design user interfaces to facilitate the adoption of applications among the final users. “The workshop combined these recommendations with an exercise that improved the technical comprehension, permitting the usage of JDeveloper to set forth our solutions,” he said. He added: “The first session that I really enjoyed was the five Fusion design principles. It was incredible to discover how these simple principles were included in an inherit manner in Fusion Applications, and I had been using many of them applying only ADF components.  Another topic that I enjoyed a lot was the eight recommendations about the visual design of UIs. The issues that were raised in that lesson are unknown to the developers and of great value to achieve an attractive presentation layer to the end users.  Participate in this workshop, and include these usability features in your projects and in this manner not only to facilitate and improve the user productivity, but also to distinguish you as a professional who takes advantage fully of the functionalities offered by Oracle technology. Praveen Pillalamarri came to the workshop to learn about the difficulties faced in UI and UX development, and how this can be resolved with the help of ADF.  He also appreciated the opportunity to talk with other individuals who came to the workshop. Pillalmarri said, “The way we looked at things in terms of work and projects were sharpened.  UI and UX design knowledge shared by you was quite interesting, especially the minute things which we ignored in the UI or UX design.” Plinio Arbizu, Services & Processes Solutions S. A., Richard Bingham, Oracle, Balaji Kamepalli, & Praveen Pillalamarri, EiS TechnologiesReady to spread the wordIn EMEA, Oracle customers and partners have access to three world-class trainers via Platform Technology Solutions: Mireille Duroussaud, Flavius Sana, and Angelo Santagata. Contact Andre Pavanello if you like to experience this workshop firsthand, or you have customers or partners who would benefit from the training.We are looking to bring the event to the U.S. in spring 2013. If you have interest in this kind of a workshop, leave a comment below. For those who want to follow the action, join the ADF Enterprise Methodology Group run by Oracle’s Chris Muir. Ask questions and continue with the conversation in this forum, or check blogs.oracle.com/usableapps for topics emerging from the workshop.

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  • July, the 31 Days of SQL Server DMO’s – Day 2 (sys.dm_exec_sessions)

    - by Tamarick Hill
      This sys.dm_exec_sessions DMV is another Server-Scoped DMV which returns information for each authenticated session that is running on your SQL Server box. Lets take a look at some of the information that this DMV returns. SELECT * FROM sys.dm_exec_sessions This DMV is very similar to the DMV we reviewed yesterday, sys.dm_exec_requests, and returns some of the same information such as reads, writes, and status for a given session_id (SPID). But this DMV returns additional information such as the Host name of the machine that owns the SPID, the program that is being used to connect to SQL Server, and the Client interface name. In addition to this information, this DMV also provides useful information on session level settings that may be on or off such as quoted identifier, arithabort, ansi padding, ansi nulls, etc. This DMV will also provide information about what specific isolation level the session is executing under and if the default deadlock priority for your SPID has been changed from the default. Lastly, this DMV provides you with an Original Login Name, which comes in handy whenever you have some type of context switching taking place due to an ‘EXECUTE AS’ statement being used and you need to identify the original login that started a session. For more information on this DMV, please see the below Books Online link: http://msdn.microsoft.com/en-us/library/ms176013.aspx

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  • SQL SERVER – Guest Post – Jacob Sebastian – Filestream – Wait Types – Wait Queues – Day 22 of 28

    - by pinaldave
    Jacob Sebastian is a SQL Server MVP, Author, Speaker and Trainer. Jacob is one of the top rated expert community. Jacob wrote the book The Art of XSD – SQL Server XML Schema Collections and wrote the XML Chapter in SQL Server 2008 Bible. See his Blog | Profile. He is currently researching on the subject of Filestream and have submitted this interesting article on the very subject. What is FILESTREAM? FILESTREAM is a new feature introduced in SQL Server 2008 which provides an efficient storage and management option for BLOB data. Many applications that deal with BLOB data today stores them in the file system and stores the path to the file in the relational tables. Storing BLOB data in the file system is more efficient that storing them in the database. However, this brings up a few disadvantages as well. When the BLOB data is stored in the file system, it is hard to ensure transactional consistency between the file system data and relational data. Some applications store the BLOB data within the database to overcome the limitations mentioned earlier. This approach ensures transactional consistency between the relational data and BLOB data, but is very bad in terms of performance. FILESTREAM combines the benefits of both approaches mentioned above without the disadvantages we examined. FILESTREAM stores the BLOB data in the file system (thus takes advantage of the IO Streaming capabilities of NTFS) and ensures transactional consistency between the BLOB data in the file system and the relational data in the database. For more information on the FILESTREAM feature, visit: http://beyondrelational.com/filestream/default.aspx FILESTREAM Wait Types Since this series is on the different SQL Server wait types, let us take a look at the various wait types that are related to the FILESTREAM feature. FS_FC_RWLOCK This wait type is generated by FILESTREAM Garbage Collector. This occurs when Garbage collection is disabled prior to a backup/restore operation or when a garbage collection cycle is being executed. FS_GARBAGE_COLLECTOR_SHUTDOWN This wait type occurs when during the cleanup process of a garbage collection cycle. It indicates that that garbage collector is waiting for the cleanup tasks to be completed. FS_HEADER_RWLOCK This wait type indicates that the process is waiting for obtaining access to the FILESTREAM header file for read or write operation. The FILESTREAM header is a disk file located in the FILESTREAM data container and is named “filestream.hdr”. FS_LOGTRUNC_RWLOCK This wait type indicates that the process is trying to perform a FILESTREAM log truncation related operation. It can be either a log truncate operation or to disable log truncation prior to a backup or restore operation. FSA_FORCE_OWN_XACT This wait type occurs when a FILESTREAM file I/O operation needs to bind to the associated transaction, but the transaction is currently owned by another session. FSAGENT This wait type occurs when a FILESTREAM file I/O operation is waiting for a FILESTREAM agent resource that is being used by another file I/O operation. FSTR_CONFIG_MUTEX This wait type occurs when there is a wait for another FILESTREAM feature reconfiguration to be completed. FSTR_CONFIG_RWLOCK This wait type occurs when there is a wait to serialize access to the FILESTREAM configuration parameters. Waits and Performance System waits has got a direct relationship with the overall performance. In most cases, when waits increase the performance degrades. SQL Server documentation does not say much about how we can reduce these waits. However, following the FILESTREAM best practices will help you to improve the overall performance and reduce the wait types to a good extend. Read all the post in the Wait Types and Queue series. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, PostADay, Readers Contribution, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, SQL Wait Stats, SQL Wait Types, T SQL, Technology Tagged: Filestream

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  • GWB | 30 Posts in 60 Days Update

    - by Staff of Geeks
    One month after the contest started, we definitely have some leaders and one blogger who has reached the mark.  Keep up the good work guys, I have really enjoyed the content being produced by our bloggers. Current Winners: Enrique Lima (37 posts) - http://geekswithblogs.net/enriquelima Almost There: Stuart Brierley (28 posts) - http://geekswithblogs.net/StuartBrierley Dave Campbell (26 posts) - http://geekswithblogs.net/WynApseTechnicalMusings Eric Nelson (23 posts) - http://geekswithblogs.net/iupdateable Coming Along: Liam McLennan (17 posts) - http://geekswithblogs.net/liammclennan Christopher House (13 posts) - http://geekswithblogs.net/13DaysaWeek mbcrump (13 posts) - http://geekswithblogs.net/mbcrump Steve Michelotti (10 posts) - http://geekswithblogs.net/michelotti Michael Freidgeim (9 posts) - http://geekswithblogs.net/mnf MarkPearl (9 posts) - http://geekswithblogs.net/MarkPearl Brian Schroer (8 posts) - http://geekswithblogs.net/brians Chris Williams (8 posts) - http://geekswithblogs.net/cwilliams CatherineRussell (7 posts) - http://geekswithblogs.net/CatherineRussell Shawn Cicoria (7 posts) - http://geekswithblogs.net/cicorias Matt Christian (7 posts) - http://geekswithblogs.net/CodeBlog James Michael Hare (7 posts) - http://geekswithblogs.net/BlackRabbitCoder John Blumenauer (7 posts) - http://geekswithblogs.net/jblumenauer Scott Dorman (7 posts) - http://geekswithblogs.net/sdorman   Technorati Tags: Standings,Geekswithblogs,30 in 60

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