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• Bob Dorr’s SQL I/O Presentation on PSS Blog

  - by Jonathan Kehayias

  In case you missed it, Bob Dorr from the PSS Team posted an amazing blog post today yesterday with all of the slides and speaker notes from his SQL Server I/O presentation.  This is a must read for and Database Professional using SQL Server. http://blogs.msdn.com/psssql/archive/2010/03/24/how-it-works-bob-dorr-s-sql-server-i-o-presentation.aspx Share this post: email it! | bookmark it! | digg it! | reddit! | kick it! | live it!...(read more)

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• Troubleshooting Application Timeouts in SQL Server

  - by Tara Kizer

  I recently received the following email from a blog reader: "We are having an OLTP database instance, using SQL Server 2005 with little to moderate traffic (10-20 requests/min). There are also bulk imports that occur at regular intervals in this DB and the import duration ranges between 10secs to 1 min, depending on the data size. Intermittently (2-3 times in a week), we face an issue, where queries get timed out (default of 30 secs set in application). On analyzing, we found two stored procedures, having queries with multiple table joins inside them of taking a long time (5-10 mins) in getting executed, when ideally the execution duration ranges between 5-10 secs. Execution plan of the same displayed Clustered Index Scan happening instead of Clustered Index Seek. All required Indexes are found to be present and Index fragmentation is also minimal as we Rebuild Indexes regularly alongwith Updating Statistics. With no other alternate options occuring to us, we restarted SQL server and thereafter the performance was back on track. But sometimes it was still giving timeout errors for some hits and so we also restarted IIS and that stopped the problem as of now." Rather than respond directly to the blog reader, I thought it would be more interesting to share my thoughts on this issue in a blog. There are a few things that I can think of that could cause abnormal timeouts: Blocking Bad plan in cache Outdated statistics Hardware bottleneck To determine if blocking is the issue, we can easily run sp_who/sp_who2 or a query directly on sysprocesses (select * from master..sysprocesses where blocking <> 0).  If blocking is present and consistent, then you'll need to determine whether or not to kill the parent blocking process.  Killing a process will cause the transaction to rollback, so you need to proceed with caution.  Killing the parent blocking process is only a temporary solution, so you'll need to do more thorough analysis to figure out why the blocking was present.  You should look into missing indexes and perhaps consider changing the database's isolation level to READ_COMMITTED_SNAPSHOT. The blog reader mentions that the execution plan shows a clustered index scan when a clustered index seek is normal for the stored procedure.  A clustered index scan might have been chosen either because that is what is in cache already or because of out of date statistics.  The blog reader mentions that bulk imports occur at regular intervals, so outdated statistics is definitely something that could cause this issue.  The blog reader may need to update statistics after imports are done if the imports are changing a lot of data (greater than 10%).  If the statistics are good, then the query optimizer might have chosen to scan rather than seek in a previous execution because the scan was determined to be less costly due to the value of an input parameter.  If this parameter value is rare, then its execution plan in cache is what we call a bad plan.  You want the best plan in cache for the most frequent parameter values.  If a bad plan is a recurring problem on your system, then you should consider rewriting the stored procedure.  You might want to break up the code into multiple stored procedures so that each can have a different execution plan in cache. To remove a bad plan from cache, you can recompile the stored procedure.  An alternative method is to run DBCC FREEPROCACHE which drops the procedure cache.  It is better to recompile stored procedures rather than dropping the procedure cache as dropping the procedure cache affects all plans in cache rather than just the ones that were bad, so there will be a temporary performance penalty until the plans are loaded into cache again. To determine if there is a hardware bottleneck occurring such as slow I/O or high CPU utilization, you will need to run Performance Monitor on the database server.  Hopefully you already have a baseline of the server so you know what is normal and what is not.  Be on the lookout for I/O requests taking longer than 12 milliseconds and CPU utilization over 90%.  The servers that I support typically are under 30% CPU utilization, but your baseline could be higher and be within a normal range. If restarting the SQL Server service fixes the problem, then the problem was most likely due to blocking or a bad plan in the procedure cache.  Rather than restarting the SQL Server service, which causes downtime, the blog reader should instead analyze the above mentioned things.  Proceed with caution when restarting the SQL Server service as all transactions that have not completed will be rolled back at startup.  This crash recovery process could take longer than normal if there was a long-running transaction running when the service was stopped.  Until the crash recovery process is completed on the database, it is unavailable to your applications. If restarting IIS fixes the problem, then the problem might not have been inside SQL Server.  Prior to taking this step, you should do analysis of the above mentioned things. If you can think of other reasons why the blog reader is facing this issue a few times a week, I'd love to hear your thoughts via a blog comment.

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• Workaround for datadude deployment bug - NullReferenceException

  - by jamiet

  I have come across a bug in Visual Studio 2010 Database Projects (aka datadude aka DPro aka Visual Studio Database Development Tools aka Visual Studio Team Edition for Database Professionals aka Juneau aka SQL Server Data Tools) that other people may encounter so, for the purposes of googling, I'm writing this blog post about it. Through my own googling I discovered that a Connect bug had already been raised about it (VS2010 Database project deploy - “SqlDeployTask” task failed unexpectedly, NullReferenceException), and coincidentally enough it was raised by my former colleague Tom Hunter (whom I have mentioned here before as the superhuman Tom Hunter) although it has not (at this time) received a reply from Microsoft. Tom provided a repro, namely that this syntactically valid function definition: CREATE FUNCTION [dbo].[Function1]()RETURNS TABLEASRETURN (    WITH cte AS (    SELECT 1 AS [c1]    FROM [$(Database3)].[dbo].[Table1]   )   SELECT 1 AS [c1]   FROM cte) would produce this nasty unhelpful error upon deployment: C:\Program Files (x86)\MSBuild\Microsoft\VisualStudio\v10.0\TeamData\Microsoft.Data.Schema.TSqlTasks.targets(120,5): Error MSB4018: The "SqlDeployTask" task failed unexpectedly.System.NullReferenceException: Object reference not set to an instance of an object.   at Microsoft.Data.Schema.Sql.SchemaModel.SqlModelComparerBase.VariableSubstitution(SqlScriptProperty propertyValue, IDictionary`2 variables, Boolean& isChanged)   at Microsoft.Data.Schema.Sql.SchemaModel.SqlModelComparerBase.ArePropertiesEqual(IModelElement source, IModelElement target, ModelPropertyClass propertyClass, ModelComparerConfiguration configuration)   at Microsoft.Data.Schema.SchemaModel.ModelComparer.CompareProperties(IModelElement sourceElement, IModelElement targetElement, ModelComparerConfiguration configuration, ModelComparisonChangeDefinition changes)   at Microsoft.Data.Schema.SchemaModel.ModelComparer.CompareElementsWithoutCompareName(IModelElement sourceElement, IModelElement targetElement, ModelComparerConfiguration configuration, Boolean parentExplicitlyIncluded, Boolean compareElementOnly, ModelComparisonResult result, ModelComparisonChangeDefinition changes)   at Microsoft.Data.Schema.SchemaModel.ModelComparer.CompareElementsWithSameType(IModelElement sourceElement, IModelElement targetElement, ModelComparerConfiguration configuration, ModelComparisonResult result, Boolean ignoreComparingName, Boolean parentExplicitlyIncluded, Boolean compareElementOnly, Boolean compareFromRootElement, ModelComparisonChangeDefinition& changes)   at Microsoft.Data.Schema.SchemaModel.ModelComparer.CompareChildren(IModelElement sourceElement, IModelElement targetElement, ModelComparerConfiguration configuration, Boolean parentExplicitlyIncluded, Boolean compareParentElementOnly, ModelComparisonResult result, ModelComparisonChangeDefinition changes, Boolean isComposing)   at Microsoft.Data.Schema.SchemaModel.ModelComparer.CompareElementsWithoutCompareName(IModelElement sourceElement, IModelElement targetElement, ModelComparerConfiguration configuration, Boolean parentExplicitlyIncluded, Boolean compareElementOnly, ModelComparisonResult result, ModelComparisonChangeDefinition changes)   at Microsoft.Data.Schema.SchemaModel.ModelComparer.CompareElementsWithSameType(IModelElement sourceElement, IModelElement targetElement, ModelComparerConfiguration configuration, ModelComparisonResult result, Boolean ignoreComparingName, Boolean parentExplicitlyIncluded, Boolean compareElementOnly, Boolean compareFromRootElement, ModelComparisonChangeDefinition& changes)   at Microsoft.Data.Schema.SchemaModel.ModelComparer.CompareChildren(IModelElement sourceElement, IModelElement targetElement, ModelComparerConfiguration configuration, Boolean parentExplicitlyIncluded, Boolean compareParentElementOnly, ModelComparisonResult result, ModelComparisonChangeDefinition changes, Boolean isComposing)   at Microsoft.Data.Schema.SchemaModel.ModelComparer.CompareElementsWithoutCompareName(IModelElement sourceElement, IModelElement targetElement, ModelComparerConfiguration configuration, Boolean parentExplicitlyIncluded, Boolean compareElementOnly, ModelComparisonResult result, ModelComparisonChangeDefinition changes)   at Microsoft.Data.Schema.SchemaModel.ModelComparer.CompareElementsWithSameType(IModelElement sourceElement, IModelElement targetElement, ModelComparerConfiguration configuration, ModelComparisonResult result, Boolean ignoreComparingName, Boolean parentExplicitlyIncluded, Boolean compareElementOnly, Boolean compareFromRootElement, ModelComparisonChangeDefinition& changes)   at Microsoft.Data.Schema.SchemaModel.ModelComparer.CompareAllElementsForOneType(ModelElementClass type, ModelComparerConfiguration configuration, ModelComparisonResult result, Boolean compareOrphanedElements)   at Microsoft.Data.Schema.SchemaModel.ModelComparer.CompareStore(ModelStore source, ModelStore target, ModelComparerConfiguration configuration)   at Microsoft.Data.Schema.Build.SchemaDeployment.CompareModels()   at Microsoft.Data.Schema.Build.SchemaDeployment.PrepareBuildPlan()   at Microsoft.Data.Schema.Build.SchemaDeployment.Execute(Boolean executeDeployment)   at Microsoft.Data.Schema.Build.SchemaDeployment.Execute()   at Microsoft.Data.Schema.Tasks.DBDeployTask.Execute()   at Microsoft.Build.BackEnd.TaskExecutionHost.Microsoft.Build.BackEnd.ITaskExecutionHost.Execute()   at Microsoft.Build.BackEnd.TaskBuilder.ExecuteInstantiatedTask(ITaskExecutionHost taskExecutionHost, TaskLoggingContext taskLoggingContext, TaskHost taskHost, ItemBucket bucket, TaskExecutionMode howToExecuteTask, Boolean& taskResult)   Done executing task "SqlDeployTask" -- FAILED.  Done building target "DspDeploy" in project "Lloyds.UKTax.DB.UKtax.dbproj" -- FAILED. Done executing task "CallTarget" -- FAILED.Done building target "DBDeploy" in project It turns out there are a certain set of circumstances that need to be met for this error to occur: The object being deployed is an inline function  (may also exist for multistatement and scalar functions - I haven't tested that) That object includes SQLCMD variable references The object has already been deployed successfully Just to reiterate that last bullet point, the error does not occur when you deploy the function for the first time, only on the subsequent deployment.   Luckily I have a direct line into a guy on the development team so I fired off an email on Friday evening and today (Monday) I received a reply back telling me that there is a simple fix, one simply has to remove the parentheses that wrap the SQL statement. So, in the case of Tom's repro, the function definition simpy has to be changed to: CREATE FUNCTION [dbo].[Function1]()RETURNS TABLEASRETURN --(    WITH cte AS (    SELECT 1 AS [c1]    FROM [$(Database3)].[dbo].[Table1]   )   SELECT 1 AS [c1]   FROM cte--) I have commented out the offending parentheses rather than removing them just to emphasize the point. Thereafter the function will deploy fine. I tested this out on my own project this morning and can confirm that this fix does indeed work.   I have been told that the bug CAN be reproduced in the Release Candidate (RC) 0 build of SQL Server Data Tools in SQL Server 2010 so am hoping that a fix makes it in for the Release-To-Manufacturing (RTM) build. Hope this helps @jamiet

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• Agile Testing Days 2012 – Day 1 – The birth of the #unicorn…

  - by Chris George

  Still riding the high from the tutorial day, I arrived at the conference venue eager to get cracking with the days talks. The opening Keynote was “Disciplined Agile Delivery: The Foundation for Scaling Agile” presented by Scott Ambler. The general ideas behind the methodology such as not re-inventing the wheel, and being goal driven, not prescriptive in how you work certainly struck chords with how we are trying to work in my team. Scott made some interesting observations about how scrum is quite prescriptive and is this really agile? I agreed with quite a few of his points on how what works for one team may not work for another. How a team works should be driven by context and reflection, not process and prescription. However was somewhat dubious about some of the statistics he rolled out towards the end. However, out of this keynote was born something that was to transcend this one presentation. During the talk, Scott mentioned on more than one occasion “In the real world”, and at one point made reference to people living in the land of unicorns and rainbows. The challenge was then laid down on twitter for all speakers to include a unicorn in their presentations… and for the most part this happened! It became an identity for this years conference, and I’m sure something that any attendee will always associate with Agile Testing Days 2012! Following this keynote, I attended “Going agile with Automated GUI Testing – Some personal insights” by Jan Zdunek from codecentric on the vendor track. My speciality is test automation, and in particular GUI testing, so this drew me to this talk more than the others. Thankfully, it was made clear from the very start that this was not peddling any particular product (even though it was on the vendor track), and Jan faithfully stuck to that. Most of the content was not new to me, but it was really comforting to hear someone else with very similar experiences to my own. In particular, things like how GUI testing is hard and is not a silver bullet; how record & replay is NOT a good thing to do (which drew a somewhat inflammatory tweet from an automation company when I tweeted that!). Something that I have started hearing around the place, and has certainly been murmuring at work is to push more of the automation coding onto the developers. After all they are the coding experts. I agree with this to a degree, but I personally enjoy coding and find it very rewarding doing so, therefore I’d be reluctant to give it up. I think there are some better alternatives such as pairing with a developer. Lastly, Jan mentioned, almost in passing, that we should consider virtualisation for gui testing for covering configuration combinations. On my project we’ve been running our win32/.NET GUI tests in cloud virtualisation for a couple of years now… I really should write about that! After lunch the second keynote of the day was by Lisa Crispin and Janet Gregory,”Myths about Agile Testing, De-Bunked”. It started off well… with the two ladies donning Medusa style head bands whilst they disbanding several myths about agile testing! I got the impression that it was perhaps not as slick as they would have liked, but then Janet was suffering with a very sore throat so kept losing her voice. Nevertheless, the presentation was captivating, and they debunked several myths such as : “Testing is dead”, “Testers must write code”, “Agile teams always deliver faster”. I didn’t take many notes for this because it was being recorded, but unfortunately the recordings have not been posted yet so I’ll write more about this when they are. The TestLab was held during a somewhat free for all time during most of the afternoon. It looked intriguing and proved to be one of the surprising experiences of the conference for me. Run by James Lyndsay and Bart Knaack, it consisted of a number of ‘stations’ that offered different testing problems. I opted for testing a mathematical drawing app call Geogebra, the task being to pair up and exploratory test it. After an allotted time, we discussed issues we’d found and decided if we wanted to continue ‘playing’ to which we all agreed! It was fun! The last track talk of the day was “Developers Exploratory Testing – Raising the bar” by Sigge Birgisson. One of the teams at Red Gate have tried Dev or Team exploratory testing a couple of times, and I was really interested to go to the presentation that prompted that. I was not disappointed! Sigge gave a first class presentation, and not only explained what DET was all about, but also how to go about implementing it. Little tips like calling it a ‘workshop’ rather than ‘testing’ I can really see working! Monday evening saw the presentation of the award for the Most Influential Agile Testing Professional Person go to a much deserved Lisa Crispin. The evening was great, with acrobatics, magic and music. My Takeaway Triple from Day 1:  Some of the cool stuff that was suggested in the GUI Testing talk, we are already doing. I should write about that! Testing is not dead! Perhaps testing will become more of a skill than a specific role, but it is certainly not dead. Team/Developer exploratory testing… seems like a no-brainer assuming you have a team who is willing.  Day 2 – Coming soon…

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• Ted Kummert to make significant announcement related to SQL Server

  - by jamiet

  Microsoft have announced a conference call tomorrow with the head of all things SQL Server, Ted Kummert: Normally I wouldn’t take any notice of such things but the mysterious pre-conference-call-announcement (not something that the SQL Server team do regularly as I recall) has me intrigued. Logic says that it will have something to do with SQL Server R2, we shall see! @Jamiet Share this post: email it! | bookmark it! | digg it! | reddit! | kick it! | live it!

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• Buck Woody in Adelaide via LiveMeeting

  - by Rob Farley

  The URL for attendees is https://www.livemeeting.com/cc/usergroups/join?id=ADL1005&role=attend . This meeting is with Buck Woody . If you don’t know who he is, then you ought to find out! He’s a Program Manager at Microsoft on the SQL Server team, and anything else I try to say about him will not do him justice. So it’s great to have him present to the Adelaide SQL Server User Group this week. The talk is on the topic of Data-Tier Applications (new in SQL 2008 R2), and I’m sure it will be a great...(read more)

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• Buck Woody in Adelaide via LiveMeeting

  - by Rob Farley

  The URL for attendees is https://www.livemeeting.com/cc/usergroups/join?id=ADL1005&role=attend . This meeting is with Buck Woody . If you don’t know who he is, then you ought to find out! He’s a Program Manager at Microsoft on the SQL Server team, and anything else I try to say about him will not do him justice. So it’s great to have him present to the Adelaide SQL Server User Group this week. The talk is on the topic of Data-Tier Applications (new in SQL 2008 R2), and I’m sure it will be a great...(read more)

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• The SQL Server Community

  - by AllenMWhite

  In case you weren't aware of it, I absolutely love the SQL Server community. The people I've gotten to know have amazing knowledge, and they love sharing that knowledge with anyone who wants to learn. How can you not love that? It's inspiring and humbling all at the same time. There are a number of venues where the SQL Server community comes together. I'm including Twitter , the PASS Summit , the various SQL Saturday events, SQLBits , Tech Ed , and the local user groups. Each of us takes part in...(read more)

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• Deploying Data-Tier Applications of SQL Server 2008 R2

  SQL Server 2008 R2 Data-Tier Applications make database development, deployment and management much easier. When you create and build a Data Tier Application, it creates a single, self-contained unit of deployment called a DAC package. Arshad Ali shows you how to deploy the created DAC package and discusses the different methods of deployment. Free trial of SQL Backup™“SQL Backup was able to cut down my backup time significantly AND achieved a 90% compression at the same time!” Joe Cheng. Download a free trial now.

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• Quickly Investigating What's in the Tables of SQL Server Databases

  From SQL Server Management Studio it's hard to look through the first few rows of a whole lot of tables in a database. This is odd, since it is a great way to get quickly familiar with a database. Phil tidied up a SQL routine he uses to investigate databases quickly in a browser. He explains how to use it, how it works, and how to use it from PowerShell. Want faster, smaller backups you can rely on?Use SQL Backup Pro for up to 95% compression, faster file transfer and integrated DBCC CHECKDB. Download a free trial now.

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• Steps to add Log Shipping monitor into an existing SQL Server

  I have a requirement to add the Log Shipping Monitor for an existing installation. I have heard you can only complete this by rebuilding the Log Shipping infrastructure. Is that true? Are there any other options? In this tip I will explain how we can add the Log Shipping monitor to a SQL Server 2005, 2008, 2008 R2 or 2012 environment without rebuilding the Log Shipping installation. "It's the freaking iPhone of SQL monitoring""Everyone just gets it… that has tremendous value" - Rob Sullivan, DBA, IdeasRun. Get started with SQL Monitor today - download a free trial.

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• Get script for every action in SQL Server Management Studio

  I am always conscious to keep a record of all operations performed on my database servers. Operations through T-SQL in an SSMS query pane can easily be saved in query files. For table modifications through SSMS designer I have predefined setting to generate T-SQL scripts. However there are numerous database and server level tasks that I use the SSMS GUI and I would like to have a script of these changes for later reference. Examples of such actions through the SSMS GUI are backup/restore, changing compatibility level of a database, manipulating permissions, dealing with database or log files or creating/manipulating any login/user. I am looking for any way to generate T-SQL code for such actions, so that it may be kept for later reference

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• On Comparing Tables in SQL Server

  How do you compare two SQL tables? Every SQL Developer or DBA knows the answer, which is 'it depends'. It is not just the size of the table or the type of data in it but what you want to achieve. Phil Factor sets about to cover the basics and point out some snags and advantages to the various techniques. FREE eBook – "45 Database Performance Tips for Developers"Improve your database performance with 45 tips from SQL Server MVPs and industry experts. Get the eBook here.

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• SQL Saturday #310 - Dublin, Ireland

  SQL Saturday is coming to Dublin on September 20, 2014. Come for a free day of SQL Server training and networking. This year's conference features a mix of levels, topics, and speakers like Buck Woody (Big Data), Jen Stirrup (PowerBI), Denny Cherry (Storage), Red Gate's Tom Austin (Continuous integration), and more. Register while space is available. Need to compare and sync database schemas?Let SQL Compare do the hard work. ”With the productivity I'll get out of this tool, it's like buying time.” Robert Sondles. Download a free trial.

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• Data Conversion in SQL Server

  Most of the time, you do not have to worry about implicit conversion in SQL expressions, or when assigning a value to a column. Just occasionally, though, you'll find that data gets truncated, queries run slowly, or comparisons just seem plain wrong. Robert Sheldon explains why you sometimes need to be very careful if you mix data types when manipulating values. Free trial of SQL Backup™“SQL Backup was able to cut down my backup time significantly AND achieved a 90% compression at the same time!” Joe Cheng. Download a free trial now.

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• How to Identify and Backup the Latest SQL Server Database in a Series

  I have to support a third party application that periodically creates a new database on the fly. This obviously causes issues with our backup mechanisms. The databases have a particular pattern for naming, so I can identify the set of databases, however, I need to make sure I'm always backing up the newest one. Read this tip to ensure you are backing up your latest database in a series. Is your SQL Database under Version Control?SSMS plug-in SQL Source Control connects SVN, TFS, Git, Hg and all others to SQL Server. Learn more.

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• Free eBook: SQL Server Execution Plans, Second Edition

  Every day, out in the various online forums devoted to SQL Server, and on Twitter, the same types of questions come up repeatedly: Why is this query running slowly? Why is SQL Server ignoring my index? Why does this query run quickly sometimes and slowly at others? My response is the same in each case: have you looked at the execution plan? "A real time saver" Andy Doyle, Head of IT ServicesAndy and his team saved time by automating backup and restores with SQL Backup Pro. Find out how much time you could save. Download a free trial now.

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• Calculating Values within a Rolling Window in Transact SQL

  Before the SQL Window functions were implemented, it was tricky to calculate rolling totals or moving averages efficiently in SQL Server. There are now a number of techniques, but which has the best performance? Dwain Camps gets out the metaphorical stopwatch. Get your SQL Server database under version control now!Version control is standard for applications, but databases haven’t caught up. So how can you bring database development up to speed? Why should you start? Find out…

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• Transparent Data Encryption (TDE) in SQL Server

  There are several ways to implement encryption in SQL Server; Arshad Ali focuses on Transparent Data Encryption (TDE), which was introduced in SQL Server 2008 and is available in later releases. 24% of devs don’t use database source control – make sure you aren’t one of themVersion control is standard for application code, but databases haven’t caught up. So what steps can you take to put your SQL databases under version control? Why should you start doing it? Read more to find out…

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• SQL Saturday #303 - Rochester, NY

  Don’t miss your opportunity to attend SQL Saturday #303, the largest FREE training event dedicated exclusively to SQL Server Administration, Development and Business Intelligence to hit Rochester, NY. This event also features 2 paid-for preconferences, run by Bill Pearson and David Klee. Register while space if available. 24% of devs don’t use database source control – make sure you aren’t one of themVersion control is standard for application code, but databases haven’t caught up. So what steps can you take to put your SQL databases under version control? Why should you start doing it? Read more to find out…

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• Few events I&rsquo;m speaking at in early 2013

  - by Mladen Prajdic

  2013 has started great and the SQL community is already brimming with events. At some of these events you can come say hi. I’ll be glad you do! These are the events with dates and locations that I know I’ll be speaking at so far.   February 16th: SQL Saturday #198 - Vancouver, Canada The session I’ll present in Vancouver is SQL Impossible: Restoring/Undeleting a table Yes, you read the title right. No, it's not about the usual "one table per partition" and "restore full backup then copy the data over" methods. No, there are no 3rd party tools involved. Just you and your SQL Server. Yes, it's crazy. No, it's not for production purposes. And yes, that's why it's so much fun. Prepare to dive into the world of data pages, log records, deletes, truncates and backups and how it all works together to get your table back from the endless void. Want to know more? Come and see! This is an advanced level session where we’ll dive into the internals of data pages, transaction log records and page restores.   March 8th-9th: SQL Saturday #194 - Exeter, UK In Exeter I’ll be presenting twice. On the first day I’ll have a full day precon titled: From SQL Traces to Extended Events - The next big switch This pre-con will give you insight into both of the current tracing technologies in SQL Server. The old SQL Trace which has served us well over the past 10 or so years is on its way out because the overhead and details it produces are no longer enough to deal with today's loads. The new Extended Events are a new lightweight tracing mechanism built directly into the SQLOS thus giving us information SQL Trace just couldn't. They were designed and built with performance in mind and it shows. The new Extended Events are a new lightweight tracing mechanism built directly into the SQLOS thus giving us information SQL Trace just couldn't. They were designed and built with performance in mind and it shows. Mastering Extended Events requires learning at least one new skill: XML querying. The second session I’ll have on Saturday titled: SQL Injection from website to SQL Server SQL Injection is still one of the biggest reasons various websites and applications get hacked. The solution as everyone tells us is simple. Use SQL parameters. But is that enough? In this session we'll look at how would an attacker go about using SQL Injection to gain access to your database, see its schema and data, take over the server, upload files and do various other mischief on your domain. This is a fun session that always brings out a few laughs in the audience because they didn’t realize what can be done.   April 23rd-25th: NTK conference - Bled, Slovenia (Slovenian website only) This is a conference with history. This year marks its 18th year running. It’s a relatively large IT conference that focuses on various Microsoft technologies like .Net, Azure, SQL Server, Exchange, Security, etc… The main session’s language is Slovenian but this is slowly changing so it’s becoming more interesting for foreign attendees. This year it’s happening in the beautiful town of Bled in the Alps. The scenery alone is worth the visit, wouldn’t you agree? And this year there are quite a few well known speakers present! Session title isn’t known yet.       May 2nd-4th: SQL Bits XI – Nottingham, UK SQL Bits is the largest SQL Server conference in Europe. It’s a 3 day conference with top speakers and content all dedicated to SQL Server. The session I’ll present here is an hour long version of the precon I’ll give in Exeter. From SQL Traces to Extended Events - The next big switch The session description is the same as for the Exeter precon but we'll focus more on how the Extended Events work with only a brief overview of old SQL Trace architecture.

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• SQL Server Optimizer Malfunction?

  - by Tony Davis

  There was a sharp intake of breath from the audience when Adam Machanic declared the SQL Server optimizer to be essentially "stuck in 1997". It was during his fascinating "Query Tuning Mastery: Manhandling Parallelism" session at the recent PASS SQL Summit. Paraphrasing somewhat, Adam (blog | @AdamMachanic) offered a convincing argument that the optimizer often delivers flawed plans based on assumptions that are no longer valid with today’s hardware. In 1997, when Microsoft engineers re-designed the database engine for SQL Server 7.0, SQL Server got its initial implementation of a cost-based optimizer. Up to SQL Server 2000, the developer often had to deploy a steady stream of hints in SQL statements to combat the occasionally wilful plan choices made by the optimizer. However, with each successive release, the optimizer has evolved and improved in its decision-making. It is still prone to the occasional stumble when we tackle difficult problems, join large numbers of tables, perform complex aggregations, and so on, but for most of us, most of the time, the optimizer purrs along efficiently in the background. Adam, however, challenged further any assumption that the current optimizer is competent at providing the most efficient plans for our more complex analytical queries, and in particular of offering up correctly parallelized plans. He painted a picture of a present where complex analytical queries have become ever more prevalent; where disk IO is ever faster so that reads from disk come into buffer cache faster than ever; where the improving RAM-to-data ratio means that we have a better chance of finding our data in cache. Most importantly, we have more CPUs at our disposal than ever before. To get these queries to perform, we not only need to have the right indexes, but also to be able to split the data up into subsets and spread its processing evenly across all these available CPUs. Improvements such as support for ColumnStore indexes are taking things in the right direction, but, unfortunately, deficiencies in the current Optimizer mean that SQL Server is yet to be able to exploit properly all those extra CPUs. Adam’s contention was that the current optimizer uses essentially the same costing model for many of its core operations as it did back in the days of SQL Server 7, based on assumptions that are no longer valid. One example he gave was a "slow disk" bias that may have been valid back in 1997 but certainly is not on modern disk systems. Essentially, the optimizer assesses the relative cost of serial versus parallel plans based on the assumption that there is no IO cost benefit from parallelization, only CPU. It assumes that a single request will saturate the IO channel, and so a query would not run any faster if we parallelized IO because the disk system simply wouldn’t be able to handle the extra pressure. As such, the optimizer often decides that a serial plan is lower cost, often in cases where a parallel plan would improve performance dramatically. It was challenging and thought provoking stuff, as were his techniques for driving parallelism through query logic based on subsets of rows that define the "grain" of the query. I highly recommend you catch the session if you missed it. I’m interested to hear though, when and how often people feel the force of the optimizer’s shortcomings. Barring mistakes, such as stale statistics, how often do you feel the Optimizer fails to find the plan you think it should, and what are the most common causes? Is it fighting to induce it toward parallelism? Combating unexpected plans, arising from table partitioning? Something altogether more prosaic? Cheers, Tony.

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• XML parsing error: 'A string literal was expected' when inserting values into table

  - by Christian

  In Microsoft Sequel Server 2008 I am attempting to insert values into an sql table with the columns type_id of datatype int and xml_info of datatype XML. I am using the following query: INSERT INTO tbl_applied_devices ([type_id],[xml_info]) VALUES (1,'<Profile ID=99><Server><ID>BC4A18CA-AFB5-4268-BDA9-C990DAFE7783</ID> <Name>localhost</Name><Services></Services></Server></Profile>') But I keep getting this error: Msg 9413, Level 16, State 1, Line 4 XML parsing: line 1, character 13, A string literal was expected What am I doing incorrectly? Thank you for the help. EDIT: I found that the source of the error is the xml element's ID attribute, where seems to be what is causing the error. How can I correctly insert xml with an attribute ? Do I need to somehow escape one of the characters?

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• Linq to sql Invalid column name

  - by Ivo

  I am using VS 2010 and Linq-to-sql I have deleted a couple of columns from my table, whatever I try I keep getting and "invalide column name" error with the old/deleted column when I try to insert a record. What tried: remove table,save, and drag it back on create new dblm with an other name created new project and create new dbml there Also the name of the deleted column does not exist in the generated code of the dbml anymore, but still I get an exception saying that column does not exists. Anyone got a suggestion how to solve this problem?

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• is of a type that is invalid for use as a key column in an index.

  - by acidzombie24

  I have an error at Column 'key' in table 'misc_info' is of a type that is invalid for use as a key column in an index. where key is a nvarchar(max). A quick google found this. It however doesnt explain what a solution is. How do i create something like Dictionary where the key and value are both strings and obviously the key must be unique and is single. My sql statement was create table [misc_info] ( [id] INTEGER PRIMARY KEY IDENTITY NOT NULL, [key] nvarchar(max) UNIQUE NOT NULL, [value] nvarchar(max) NOT NULL);

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