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• F# in ASP.NET, mathematics and testing

  - by DigiMortal

  Starting from Visual Studio 2010 F# is full member of .NET Framework languages family. It is functional language with syntax specific to functional languages but I think it is time for us also notice and study functional languages. In this posting I will show you some examples about cool things other people have done using F#. F# and ASP.NET As I am ASP/ASP.NET MVP I am – of course – interested in how people use different languages and technologies with ASP.NET. C# MVP Tomáš Petrícek writes about developing ASP.NET MVC applications using F#. He also shows how to use LINQ To SQL in F# (using F# PowerPack) and provides sample solution and Visual Studio 2010 template for F# MVC web applications. You may also find interesting how you can create controllers in F#. Excellent work, Tomáš! Vladimir Matveev has interesting example about how to use F# and ApplicationHost class to process ASP.NET requests ouside of IIS. This is simple and very straight-forward example and I strongly suggest you to take a look at it. Very cool example is project Strom in Codeplex. Storm is web services testing tool that is fully written on F#. Take a look at this site because Codeplex offers also source code besides binaries. Math Functional languages are strong in fields like mathematics and physics. When I wrote my C# example about BigInteger class I found out that recursive version of Fibonacci algorithm in C# is not performing well. In same time I made same experiment on F# and in F# there were no performance problems with recursive version. You can find F# version of Fibonacci algorithm from Bob Palmer’s blog posting Fibonacci numbers in F#. Although golden spiral is useful for solving many problems I looked for some practical code example and found one. Kean Walmsley published in his Through the Interface blog very interesting posting Creating Fibonacci spirals in AutoCAD using F#. There are also other cool examples you may be interested in. Using numerical components by Extreme Optimization  it is possible to make some numerical integration (quadrature method) using F# (also C# example is available). fsharp.it introduces factorials calculation on F#. Robert Pickering has made very good work on programming The Game of Life in Silverlight and F# – I definitely suggest you to try out this example as it is very illustrative too. Who wants something more complex may take a look at Newton basin fractal example in F# by Jonathan Birge. Testing After some searching and surfing I found out that there is almost everything available for F# to write tests and test your F# code. FsCheck - FsCheck is a port of Haskell's QuickCheck. Important parts of the manual for using FsCheck is almost literally "adapted" from the QuickCheck manual and paper. Any errors and omissions are entirely my responsibility. FsTest - This project is designed to Language Oriented Programming constructs around unit testing and behavior testing in F#. The goal of this project is to create a Domain Specific Language for testing F# code in a way that makes sense for functional programming. FsUnit - FsUnit makes unit-testing with F# more enjoyable. It adds a special syntax to your favorite .NET testing framework. xUnit.NET - xUnit.net is a developer testing framework, built to support Test Driven Development, with a design goal of extreme simplicity and alignment with framework features. It is compatible with .NET Framework 2.0 and later, and offers several runners: console, GUI, MSBuild, and Visual Studio integration via TestDriven.net, CodeRush Test Runner and Resharper. It also offers test project integration for ASP.NET MVC. Getting started Well, as a first thing you need Visual Studio 2010. Then take a look at these resources: F# samples @ MSDN Microsoft F# Developer Center @ MSDN F# Language Reference @ MSDN F# blog F# forums Real World Functional Programming: With Examples in F# and C# (Amazon) Happy F#-ing! :)

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• Application Performance Episode 2: Announcing the Judges!

  - by Michaela Murray

  The story so far… We’re writing a new book for ASP.NET developers, and we want you to be a part of it! If you work with ASP.NET applications, and have top tips, hard-won lessons, or sage advice for avoiding, finding, and fixing performance problems, we want to hear from you! And if your app uses SQL Server, even better – interaction with the database is critical to application performance, so we’re looking for database top tips too. There’s a Microsoft Surface apiece for the person who comes up with the best tip for SQL Server and the best tip for .NET. Of course, if your suggestion is selected for the book, you’ll get full credit, by name, Twitter handle, GitHub repository, or whatever you like. To get involved, just email your nuggets of performance wisdom to [email protected] – there are examples of what we’re looking for and full competition details at Application Performance: The Best of the Web. Enter the judges… As mentioned in my last blogpost, we have a mystery panel of celebrity judges lined up to select the prize-winning performance pointers. We’re now ready to reveal their secret identities! Judging your ASP.NET  tips will be: Jean-Phillippe Gouigoux, MCTS/MCPD Enterprise Architect and MVP Connected System Developer. He’s a board member at French software company MGDIS, and teaches algorithms, security, software tests, and ALM at the Université de Bretagne Sud. Jean-Philippe also lectures at IT conferences and writes articles for programming magazines. His book Practical Performance Profiling is published by Simple-Talk. Nik Molnar,  a New Yorker, ASP Insider, and co-founder of Glimpse, an open source ASP.NET diagnostics and debugging tool. Originally from Florida, Nik specializes in web development, building scalable, client-centric solutions. In his spare time, Nik can be found cooking up a storm in the kitchen, hanging with his wife, speaking at conferences, and working on other open source projects. Mitchel Sellers, Microsoft C# and DotNetNuke MVP. Mitchel is an experienced software architect, business leader, public speaker, and educator. He works with companies across the globe, as CEO of IowaComputerGurus Inc. Mitchel writes technical articles for online and print publications and is the author of Professional DotNetNuke Module Programming. He frequently answers questions on StackOverflow and MSDN and is an active participant in the .NET and DotNetNuke communities. Clive Tong, Software Engineer at Red Gate. In previous roles, Clive spent a lot of time working with Common LISP and enthusing about functional languages, and he’s worked with managed languages since before his first real job (which was a long time ago). Long convinced of the productivity benefits of managed languages, Clive is very interested in getting good runtime performance to keep managed languages practical for real-world development. And our trio of SQL Server specialists, ready to select your top suggestion, are (drumroll): Rodney Landrum, a SQL Server MVP who writes regularly about Integration Services, Analysis Services, and Reporting Services. He’s authored SQL Server Tacklebox, three Reporting Services books, and contributes regularly to SQLServerCentral, SQL Server Magazine, and Simple–Talk. His day job involves overseeing a large SQL Server infrastructure in Orlando. Grant Fritchey, Product Evangelist at Red Gate and SQL Server MVP. In an IT career spanning more than 20 years, Grant has written VB, VB.NET, C#, and Java. He’s been working with SQL Server since version 6.0. Grant volunteers with the Editorial Committee at PASS and has written books for Apress and Simple-Talk. Jonathan Allen, leader and founder of the PASS SQL South West user group. He’s been working with SQL Server since 1999 and enjoys performance tuning, development, and using SQL Server for business solutions. He’s spoken at SQLBits and SQL in the City, as well as local user groups across the UK. He’s also a moderator at ask.sqlservercentral.com.

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• Launch 7:Windows Phone 7 Style Live Tiles On Android Mobiles

  - by Gopinath

  Android is a great mobile OS but one thought that lingers in the mind of few Android owners is: Am I using a cheap iPhone? This is valid thought for many low end Android users as their phones runs sluggish and the user interface of Android looks like an imitation of iOS. When it comes to Windows Phone 7 users, even though their operating system features are not as great as iPhone/Android but it has its unique user interface; Windows Phone 7 user interface is a very intuitive and fresh, it’s constantly updating Live Tiles show all the required information on the home screen. Android has best mobile operating system features except UI and Windows Phone 7 has excellent user interface. How about porting Windows Phone 7 Tiles interface on an Android? That should be great. Launch 7 app brings the best of Windows Phone 7 look and feel to Android OS. Once the Launcher 7 app is installed and activated, it brings Live Tiles or constantly updating controls that show information on Android home screen. Apart from simple and smooth tiles, there are handful of customization options provided. Users can change colour of the tiles, add new tiles, enable/disable transitions. The reviews on Android Market are on the positive side with 4.4 stars by 10,000 + reviewers. Here are few user reviews 1. Does what it says. only issue for me is that the app drawer doesn’t rotate. And I would like the UI to rotate when my KB is opened. HTC desire z – Jonathan 2. Works great on atrix.Kudos to developers. Awesome. Though needs: Better notification bar More stock images of tiles Better fitting of widgets on tiles – Manny 3. Looks really good like it much more than I thought I would runs real smooth running royal ginger 2.1 – Jay 4. Omg amazing i am definetly keeping it as my default best of android and windows – Devon 5. Man! An update every week! Very very responsive developer! – Andrew You can read more reviews on Android Market here.  There is no doubt that this application is receiving rave reviews. After scanning a while through the reviews, few complaints throw light on the negative side: Battery drains a bit faster & Low end mobile run a bit sluggish. The application is available in two versions – an ad supported free version and $1.41 ad free version. Download Launcher 7 from Android Market This article titled,Launch 7:Windows Phone 7 Style Live Tiles On Android Mobiles, was originally published at Tech Dreams. Grab our rss feed or fan us on Facebook to get updates from us.

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• problem using getline with a unicode file

  - by hamishmcn

  UPDATE: Thank you to @Potatoswatter and @Jonathan Leffler for comments - rather embarrassingly I was caught out by the debugger tool tip not showing the value of a wstring correctly - however it still isn't quite working for me and I have updated the question below: If I have a small multibyte file I want to read into a string I use the following trick - I use getline with a delimeter of '\0' e.g. std::string contents_utf8; std::ifstream inf1("utf8.txt"); getline(inf1, contents_utf8, '\0'); This reads in the entire file including newlines. However if I try to do the same thing with a wide character file it doesn't work - my wstring only reads to the the first line. std::wstring contents_wide; std::wifstream inf2(L"ucs2-be.txt"); getline( inf2, contents_wide, wchar_t(0) ); //doesn't work For example my if unicode file contains the chars A and B seperated by CRLF, the hex looks like this: FE FF 00 41 00 0D 00 0A 00 42 Based on the fact that with a multibyte file getline with '\0' reads the entire file I believed that getline( inf2, contents_wide, wchar_t(0) ) should read in the entire unicode file. However it doesn't - with the example above my wide string would contain the following two wchar_ts: FF FF (If I remove the wchar_t(0) it reads in the first line as expected (ie FE FF 00 41 00 0D 00) Why doesn't wchar_t(0) work as a delimiting wchar_t of "00 00"? Thank you

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• SQL - Converting 24-hour ("military") time (2145) to "AM/PM time" (9:45 pm)

  - by CheeseConQueso

  I have 2 fields I'm working with that are stored as smallint military structured times. Edit I'm running on IBM Informix Dynamic Server Version 10.00.FC9 beg_tm and end_tm Sample values beg_tm 545 end_tm 815 beg_tm 1245 end_tm 1330 Sample output beg_tm 5:45 am end_tm 8:15 am beg_tm 12:45 pm end_tm 1:30 pm I had this working in Perl, but I'm looking for a way to do it with SQL and case statements. Is this even possible? EDIT Essentially, this formatting has to be used in an ACE report. I couldn't find a way to format it within the output section using simple blocks of if(beg_tm>=1300) then beg_tm = vbeg_tm - 1200 Where vbeg_tm is a declared char(4) variable EDIT This works for hours =1300 (EXCEPT FOR 2230 !!) select substr((beg_tm-1200),0,1)||":"||substr((beg_tm-1200),2,2) from mtg_rec where beg_tm>=1300; This works for hours < 1200 (sometimes.... 10:40 is failing) select substr((mtg_rec.beg_tm),0,(length(cast(beg_tm as varchar(4)))-2))||":"||(substr((mtg_rec.beg_tm),2,2))||" am" beg_tm from mtg_rec where mtg_no = 1; EDIT Variation of casting syntax used in Jonathan Leffler's expression approach SELECT beg_tm, cast((MOD(beg_tm/100 + 11, 12) + 1) as VARCHAR(2)) || ':' || SUBSTRING(cast((MOD(beg_tm, 100) + 100) as CHAR(3)) FROM 2) || SUBSTRING(' am pm' FROM (MOD(cast((beg_tm/1200) as INT), 2) * 3) + 1 FOR 3), end_tm, cast((MOD(end_tm/100 + 11, 12) + 1) as VARCHAR(2)) || ':' || SUBSTRING(cast((MOD(end_tm, 100) + 100) as CHAR(3)) FROM 2) || SUBSTRING(' am pm' FROM (MOD(cast((end_tm/1200) as INT), 2) * 3) + 1 FOR 3) FROM mtg_rec where mtg_no = 39;

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• Top Container Background Problem

  - by Norbert

  Here's a screenshot: http://dl.getdropbox.com/u/118004/Screen%20shot%202010-04-13%20at%202.50.49%20PM.png The red bar on the left is the background I set for the #personal div and I would like it to align to the top of the container, vertically. The problem is that I have a background for the #container-top div on top of the #container div with absolute positioning. Is there any way to move the #personal div up so there would be no space left? HTML <div id="container"> <div id="container-top"></div> <div id="personal"> <h1>Jonathan Doe</h1> <p>Lorem ipsum dolor sit amet, consectetuer adipiscing elit, sed diam nonummy nibh euismod tincidunt ut laoreet dolore magna aliqua erat volutpat.</p> </div> <!-- end #personal --> </div> <!-- end #container --> CSS #container { background: url(images/bg-mid.png) repeat-y top center; width: 835px; margin: 40px auto; position: relative; } #container-top { background: url(images/bg-top.png) no-repeat top center; position: absolute; height: 12px; width: 835px; top: -12px; } #container-bottom { background: url(images/bg-bottom.png) no-repeat top center; position: absolute; height: 27px; width: 835px; bottom: -27px; } #personal { background: url(images/personal-info.png) no-repeat 0px left; }

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• Bash Templating: How to build configuration files from templates with Bash?

  - by FractalizeR

  Hello. I'm writting a script to automate creating configuration files for Apache and PHP for my own webserver. I don't want to use any GUIs like CPanel or ISPConfig. I have some templates of Apache and PHP configuration files. Bash script needs to read templates, make variable substitution and output parsed templates into some folder. What is the best way to do that? I can think of several ways. Which one is the best or may be there are some better ways to do that? I want to do that in pure Bash (it's easy in PHP for example) 1)http://stackoverflow.com/questions/415677/how-to-repace-variables-in-a-nix-text-file template.txt: the number is ${i} the word is ${word} script.sh: #!/bin/sh #set variables i=1 word="dog" #read in template one line at the time, and replace variables #(more natural (and efficient) way, thanks to Jonathan Leffler) while read line do eval echo "$line" done < "./template.txt" BTW, how do I redirect output to external file here? Do I need to escape something if variables contain, say, quotes? 2) Using cat & sed for replacing each variable with it's value: Given template.txt: The number is ${i} The word is ${word} Command: cat template.txt | sed -e "s/\${i}/1/" | sed -e "s/\${word}/dog/" Seems bad to me because of the need to escape many different symbols and with many variables the line will be tooooo long. Can you think of some other elegant and safe solution?

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• Attempted to read or write protected memory

  - by Interfector

  I have a sample ASP.NET MVC 3 web application that is following Jonathan McCracken's Test-Drive Asp.NET MVC (great book , by the way) and I have stumbled upon a problem. Note that I'm using MVCContrib, Rhino and NUnit. [Test] public void ShouldSetLoggedInUserToViewBag() { var todoController = new TodoController(); var builder = new TestControllerBuilder(); builder.InitializeController(todoController); builder.HttpContext.User = new GenericPrincipal(new GenericIdentity("John Doe"), null); Assert.That(todoController.Index().AssertViewRendered().ViewData["UserName"], Is.EqualTo("John Doe")); } The code above always throws this error: System.AccessViolationException : Attempted to read or write protected memory. This is often an indication that other memory is corrupt. The controller action code is the following: [HttpGet] public ActionResult Index() { ViewData.Model = Todo.ThingsToBeDone; ViewBag.UserName = HttpContext.User.Identity.Name; return View(); } From what I have figured out, the app seems to crash because of the two assignements in the controller action. However, I cannot see how there are wrong!? Can anyone help me pinpoint the solution to this problem. Thank you.

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• Floating point precision in Visual C++

  - by Luigi Giaccari

  HI, I am trying to use the robust predicates for computational geometry from Jonathan Richard Shewchuk. I am not a programmer, so I am not even sure of what I am saying, I may be doing some basic mistake. The point is the predicates should allow for precise aritmthetic with adaptive floating point precision. On my computer: Asus pro31/S (Core Due Centrino Processor) they do not work. The problem may stay in the fact the my computer may use some improvements in the floating point precision taht conflicts with the one used by Shewchuk. The author says: /* On some machines, the exact arithmetic routines might be defeated by the / / use of internal extended precision floating-point registers. Sometimes / / this problem can be fixed by defining certain values to be volatile, / / thus forcing them to be stored to memory and rounded off. This isn't / / a great solution, though, as it slows the arithmetic down. */ Now what I would like to know is that there is a way, maybe some compiler option, to turn off the internal extended precision floating-point registers. I really appriaciate your help

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• Can I use POSIX signals in my Perl program to create event-driven programming?

  - by Shiftbit

  Is there any POSIX signals that I could utilize in my Perl program to create event-driven programming? Currently, I have multi-process program that is able to cross communicate but my parent thread is only able to listen to listen at one child at a time. foreach (@proc) { sysread(${$_}{'read'}, my $line, 100); #problem here chomp($line); print "Parent hears: $line\n"; } The problem is that the parent sits in a continual wait state until it receives it a signal from the first child before it can continue on. I am relying on 'pipe' for my intercommunication. My current solution is very similar to: http://stackoverflow.com/questions/2558098/how-can-i-use-pipe-to-facilitate-interprocess-communication-in-perl If possible I would like to rely on a $SIG{...} event or any non-CPAN solution. Update: As Jonathan Leffler mentioned, kill can be used to send a signal: kill USR1 = $$; # send myself a SIGUSR1 My solution will be to send a USR1 signal to my child process. This event tells the parent to listen to the particular child. child: kill USR1 => $parentPID if($customEvent); syswrite($parentPipe, $msg, $buffer); #select $parentPipe; print $parentPipe $msg; parent: $SIG{USR1} = { #get child pid? sysread($array[$pid]{'childPipe'}, $msg, $buffer); }; But how do I get my the source/child pid that signaled the parent? Have the child Identify itself in its message. What happens if two children signal USR1 at the same time?

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• Token replacement

  - by ClarkeyBoy

  Hey, I currently have a system on my website whereby I can put something like "[cfe]" anywhere in the site and, when the page is rendered, it will replace it with the root to the customer front end (same for "[afe]" and admin front end - so in the admin front end I can put "[cfe]/Default.aspx" to link to the homepage on the customer front end. This is in place as I have a development version of the site, then a test and a live version too. All 3 may have different roots to each section (for example the way the website is set up, the root to the admin front end in test is "/test/Administration/", but in live and development it is just "/Administration/"). Which version it is depends on the URL - all my development sites are in a folder called "development", whereas test is in a folder called "test" and any live urls do not contain either of these. There are also 3 different databases - one for each. All 3, obviously, require a different connection string. I also have a string replacement function in place which can change, for example, "[Product:Cards]" to point to the Cards catalogue page. Problem is that for this I go through all the products and do a replacement on "[Product:" & Product.Name() & "]". However I would like to take this further. I would like to pick up these custom strings when the page is rendered so it picks up "[Product:Cards]" and then goes off to find product "Cards" and replaces the string with a link to the Cards page, rather than looping through all the products and doing a replace just on the off chance that there are any replacements to make. One use for this, which I may start using in the future if I can figure out how to do this, is like on Wikipedia where you put the title of the page you want to point to, then a divider (think its a pipe from memory) then the link text. I would like to apply this to the above situation. This way broken links can also be picked up, and reported to admin (a major advantage as they can then locate them and remove the link or add the product / page that it refers to). I would like to take this to the stage where content of entire pages can be rearranged (kinda like web parts, but not as advanced as that). I mean like so you can put [layout type="3columnImageTopRight" image="imageurl"]Content here[/layout]. This will display, as specified, an image in the top right (with padding at the left and bottom) and 3 columns - maybe with the image spanning one or two columns). The imageurl can be specified as another token: maybe like [Image:imagename.gif] or something. This replaces it with the root to the image folder and then the specified filename. I have not really looked into how I am going to split the content into 3 columns yet, but this would be something to look at for my dissertation and then implement after my project deadline at least. Does anyone have any ideas or pointers which could help me with this? Also if this is not strictly token replacement then please point me to what it is, so I can further develop this. Thanks in advance, Regards, Richard Clarke

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• SQL SERVER – CXPACKET – Parallelism – Usual Solution – Wait Type – Day 6 of 28

  - by pinaldave

  CXPACKET has to be most popular one of all wait stats. I have commonly seen this wait stat as one of the top 5 wait stats in most of the systems with more than one CPU. Books On-Line: Occurs when trying to synchronize the query processor exchange iterator. You may consider lowering the degree of parallelism if contention on this wait type becomes a problem. CXPACKET Explanation: When a parallel operation is created for SQL Query, there are multiple threads for a single query. Each query deals with a different set of the data (or rows). Due to some reasons, one or more of the threads lag behind, creating the CXPACKET Wait Stat. There is an organizer/coordinator thread (thread 0), which takes waits for all the threads to complete and gathers result together to present on the client’s side. The organizer thread has to wait for the all the threads to finish before it can move ahead. The Wait by this organizer thread for slow threads to complete is called CXPACKET wait. Note that not all the CXPACKET wait types are bad. You might experience a case when it totally makes sense. There might also be cases when this is unavoidable. If you remove this particular wait type for any query, then that query may run slower because the parallel operations are disabled for the query. Reducing CXPACKET wait: We cannot discuss about reducing the CXPACKET wait without talking about the server workload type. OLTP: On Pure OLTP system, where the transactions are smaller and queries are not long but very quick usually, set the “Maximum Degree of Parallelism” to 1 (one). This way it makes sure that the query never goes for parallelism and does not incur more engine overhead. EXEC sys.sp_configure N'cost threshold for parallelism', N'1' GO RECONFIGURE WITH OVERRIDE GO Data-warehousing / Reporting server: As queries will be running for long time, it is advised to set the “Maximum Degree of Parallelism” to 0 (zero). This way most of the queries will utilize the parallel processor, and long running queries get a boost in their performance due to multiple processors. EXEC sys.sp_configure N'cost threshold for parallelism', N'0' GO RECONFIGURE WITH OVERRIDE GO Mixed System (OLTP & OLAP): Here is the challenge. The right balance has to be found. I have taken a very simple approach. I set the “Maximum Degree of Parallelism” to 2, which means the query still uses parallelism but only on 2 CPUs. However, I keep the “Cost Threshold for Parallelism” very high. This way, not all the queries will qualify for parallelism but only the query with higher cost will go for parallelism. I have found this to work best for a system that has OLTP queries and also where the reporting server is set up. Here, I am setting ‘Cost Threshold for Parallelism’ to 25 values (which is just for illustration); you can choose any value, and you can find it out by experimenting with the system only. In the following script, I am setting the ‘Max Degree of Parallelism’ to 2, which indicates that the query that will have a higher cost (here, more than 25) will qualify for parallel query to run on 2 CPUs. This implies that regardless of the number of CPUs, the query will select any two CPUs to execute itself. EXEC sys.sp_configure N'cost threshold for parallelism', N'25' GO EXEC sys.sp_configure N'max degree of parallelism', N'2' GO RECONFIGURE WITH OVERRIDE GO Read all the post in the Wait Types and Queue series. Additionally a must read comment of Jonathan Kehayias. Note: The information presented here is from my experience and I no way claim it to be accurate. I suggest you all to read the online book for further clarification. All the discussion of Wait Stats over here is generic and it varies from system to system. It is recommended that you test this on the development server before implementing on the production server. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: DMV, 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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• SQLIO Writes

  - by Grant Fritchey

  SQLIO is a fantastic utility for testing the abilities of the disks in your system. It has a very unfortunate name though, since it's not really a SQL Server testing utility at all. It really is a disk utility. They ought to call it DiskIO because they'd get more people using I think. Anyway, branding is not the point of this blog post. Writes are the point of this blog post. SQLIO works by slamming your disk. It performs as mean reads as it can or it performs as many writes as it can depending on how you've configured your tests. There are much smarter people than me who will get into all the various types of tests you should run. I'd suggest reading a bit of what Jonathan Kehayias (blog|twitter) has to say or wade into Denny Cherry's (blog|twitter) work. They're going to do a better job than I can describing all the benefits and mechanisms around using this excellent piece of software. My concerns are very focused. I needed to set up a series of tests to see how well our product SQL Storage Compress worked. I wanted to know the effects it would have on a system, the disk for sure, but also memory and CPU. How to stress the system? SQLIO of course. But when I set it up and ran it, following the documentation that comes with it, I was seeing better than 99% compression on the files. Don't get me wrong. Our product is magnificent, wonderful, all things great and beautiful, gets you coffee in the morning and is made mostly from bacon. But 99% compression. No, it's not that good. So what's up? Well, it's the configuration. The default mechanism is to load up a file, something large that will overwhelm your disk cache. You're instructed to load the file with a character 0x0. I never got a computer science degree. I went to film school. Because of this, I didn't memorize ASCII tables so when I saw this, I thought it was zero's or something. Nope. It's NULL. That's right, you're making a very large file, but you're filling it with NULL values. That's actually ok when all you're testing is the disk sub-system. But, when you want to test a compression and decompression, that can be an issue. I got around this fairly quickly. Instead of generating a file filled with NULL values, I just copied a database file for my tests. And to test it with SQL Storage Compress, I used a database file that had already been run through compression (about 40% compression on that file if you're interested). Now the reads were taken care of. I am seeing very realistic performance from decompressing the information for reads through SQLIO. But what about writes? Well, the issue is, what does SQLIO write? I don't have access to the code. But I do have access to the results. I did two different tests, just to be sure of what I was seeing. First test, use the .DAT file as described in the documentation. I opened the .DAT file after I was done with SQLIO, using WordPad. Guess what? It's a giant file full of air. SQLIO writes NULL values. What does that do to compression? I did the test again on a copy of an uncompressed database file. Then I ran the original and the SQLIO modified copy through ZIP to see what happened. I got better than 99% compression out of the SQLIO modified file (original file of 624,896kb went to 275,871kb compressed, after SQLIO it went to 608kb compressed). So, what does SQLIO write? It writes air. If you're trying to test it with compression or maybe some other type of file storage mechanism like dedupe, you need to know this because your tests really won't be valid. Should I find some other mechanism for testing? Yeah, if all I'm interested in is establishing performance to my own satisfaction, yes. But, I want to be able to compare my results with other people's results and we all need to be using the same tool in order for that to happen. SQLIO is the common mechanism that most people I know use to establish disk performance behavior. It'd be better if we could get SQLIO to do writes in some other fashion. Oh, and before I go, I get to brag a bit. Measuring IOPS, SQL Storage Compress outperforms my disk alone by about 30%.

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• Which functions in the C standard library commonly encourage bad practice?

  - by Ninefingers

  Hello all, This is inspired by this question and the comments on one particular answer in that I learnt that strncpy is not a very safe string handling function in C and that it pads zeros, until it reaches n, something I was unaware of. Specifically, to quote R.. strncpy does not null-terminate, and does null-pad the whole remainder of the destination buffer, which is a huge waste of time. You can work around the former by adding your own null padding, but not the latter. It was never intended for use as a "safe string handling" function, but for working with fixed-size fields in Unix directory tables and database files. snprintf(dest, n, "%s", src) is the only correct "safe strcpy" in standard C, but it's likely to be a lot slower. By the way, truncation in itself can be a major bug and in some cases might lead to privilege elevation or DoS, so throwing "safe" string functions that truncate their output at a problem is not a way to make it "safe" or "secure". Instead, you should ensure that the destination buffer is the right size and simply use strcpy (or better yet, memcpy if you already know the source string length). And from Jonathan Leffler Note that strncat() is even more confusing in its interface than strncpy() - what exactly is that length argument, again? It isn't what you'd expect based on what you supply strncpy() etc - so it is more error prone even than strncpy(). For copying strings around, I'm increasingly of the opinion that there is a strong argument that you only need memmove() because you always know all the sizes ahead of time and make sure there's enough space ahead of time. Use memmove() in preference to any of strcpy(), strcat(), strncpy(), strncat(), memcpy(). So, I'm clearly a little rusty on the C standard library. Therefore, I'd like to pose the question: What C standard library functions are used inappropriately/in ways that may cause/lead to security problems/code defects/inefficiencies? In the interests of objectivity, I have a number of criteria for an answer: Please, if you can, cite design reasons behind the function in question i.e. its intended purpose. Please highlight the misuse to which the code is currently put. Please state why that misuse may lead towards a problem. I know that should be obvious but it prevents soft answers. Please avoid: Debates over naming conventions of functions (except where this unequivocably causes confusion). "I prefer x over y" - preference is ok, we all have them but I'm interested in actual unexpected side effects and how to guard against them. As this is likely to be considered subjective and has no definite answer I'm flagging for community wiki straight away. I am also working as per C99.

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• how to use SQL wildcard % with Queryset extra>select?

  - by tylias

  I'm trying to add weights to search terms I'm using to filter a queryset. Using the '%' wildcard is causing me some problems. I'm using the extra() modifier to add a weight parameter to the queryset, which I will be using to inform a sort ordering. (See http://docs.djangoproject.com/en/1.1/ref/models/querysets/#extra-select-none-where-none-params-none-tables-none-order-by-none-select-params-none ) Here's the gist of the code: def viewname(request) ... exact_matchstrings="" exact_matchstrings.append("(accountprofile.first_name LIKE '" + term + "')") exact_matchstrings.append("(accountprofile.first_name LIKE '" + term + '\%' + "')") extraquerystring = " + ".join(exact_matchstrings) return_queryset = return_queryset.extra( select = { 'match_weight': extraquerystring }, ) The effect I'm going for is that if the search term matches exactly, the weight associated with the record is 2, but if the term merely starts with the search term and isn't an exact match, the weight is 1. (for example, if 'term' = 'Jon', an entry with first_name='Jon' gets a weight of 2 but an entry with an entry with first_name = 'Jonathan' gets a weight of 1.) I can test the statement in SQL and it seems to work well enough. If I make this SQL query from the mysql shell, no problem: select (first_name like "Carl") + (first_name like "Car%") from accountprofile; But trying to run it via the extra() modifier in my view code and evaluating the resulting queryset gives me the following error: Traceback (most recent call last): File "<console>", line 1, in <module> File "/usr/local/lib/python2.6/dist-packages/django/db/models/query.py", line 68, in __repr__ data = list(self[:REPR_OUTPUT_SIZE + 1]) File "/usr/local/lib/python2.6/dist-packages/django/db/models/query.py", line 83, in __len__ self._result_cache.extend(list(self._iter)) File "/usr/local/lib/python2.6/dist-packages/django/db/models/query.py", line 238, in iterator for row in self.query.results_iter(): File "/usr/local/lib/python2.6/dist-packages/django/db/models/sql/query.py", line 287, in results_iter for rows in self.execute_sql(MULTI): File "/usr/local/lib/python2.6/dist-packages/django/db/models/sql/query.py", line 2369, in execute_sql cursor.execute(sql, params) File "/usr/local/lib/python2.6/dist-packages/django/db/backends/util.py", line 22, in execute sql = self.db.ops.last_executed_query(self.cursor, sql, params) File "/usr/local/lib/python2.6/dist-packages/django/db/backends/__init__.py", line 217, in last_executed_query return smart_unicode(sql) % u_params ValueError: unsupported format character ''' (0x27) at index 309 I've tried it escaping and not escaping % wildcard but that doesn't solve the problem. Doesn't seem to affect it at all, really. Any ideas?

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• Installing my sdist from PyPI puts the files in the wrong places

  - by Tartley

  Hey. My problem is that when I upload my Python package to PyPI, and then install it from there using pip, my app breaks because it installs my files into completely different locations than when I simply install the exact same package from a local sdist. Installing from the local sdist puts files on my system like this: /Python27/ Lib/ site-packages/ gloopy-0.1.alpha-py2.7.egg/ (egg and install info files) data/ (images and shader source) doc/ (html) examples/ (.py scripts that use the library) gloopy/ (source) This is much as I'd expect, and works fine (e.g. my source can find my data dir, because they lie next to each other, just like they do in development.) If I upload the same sdist to PyPI and then install it from there, using pip, then things look very different: /Python27/ data/ (images and shader source) doc/ (html) Lib/ site-packages/ gloopy-0.1.alpha-py2.7.egg/ (egg and install info files) gloopy/ (source files) examples/ (.py scripts that use the library) This doesn't work at all - my app can't find its data files, plus obviously it's a mess, polluting the top-level /python27 directory with all my junk. What am I doing wrong? How do I make the pip install behave like the local sdist install? Is that even what I should be trying to achieve? Details I have setuptools installed, and also distribute, and I'm calling distribute_setup.use_setuptools() WindowsXP, Python2.7. My development directory looks like this: /gloopy /data (image files and GLSL shader souce read at runtime) /doc (html files) /examples (some scripts to show off the library) /gloopy (the library itself) My MANIFEST.in mentions all the files I want to be included in the sdist, including everything in the data, examples and doc directories: recursive-include data *.* recursive-include examples *.py recursive-include doc/html *.html *.css *.js *.png include LICENSE.txt include TODO.txt My setup.py is quite verbose, but I guess the best thing is to include it here, right? I also includes duplicate references to the same data / doc / examples directories as are mentioned in the MANIFEST.in, because I understand this is required in order for these files to be copied from the sdist to the system during install. NAME = 'gloopy' VERSION= __import__(NAME).VERSION RELEASE = __import__(NAME).RELEASE SCRIPT = None CONSOLE = False def main(): import sys from pprint import pprint from setup_utils import distribute_setup from setup_utils.sdist_setup import get_sdist_config distribute_setup.use_setuptools() from setuptools import setup description, long_description = read_description() config = dict( name=name, version=version, description=description, long_description=long_description, keywords='', packages=find_packages(), data_files=[ ('examples', glob('examples/*.py')), ('data/shaders', glob('data/shaders/*.*')), ('doc', glob('doc/html/*.*')), ('doc/_images', glob('doc/html/_images/*.*')), ('doc/_modules', glob('doc/html/_modules/*.*')), ('doc/_modules/gloopy', glob('doc/html/_modules/gloopy/*.*')), ('doc/_modules/gloopy/geom', glob('doc/html/_modules/gloopy/geom/*.*')), ('doc/_modules/gloopy/move', glob('doc/html/_modules/gloopy/move/*.*')), ('doc/_modules/gloopy/shapes', glob('doc/html/_modules/gloopy/shapes/*.*')), ('doc/_modules/gloopy/util', glob('doc/html/_modules/gloopy/util/*.*')), ('doc/_modules/gloopy/view', glob('doc/html/_modules/gloopy/view/*.*')), ('doc/_static', glob('doc/html/_static/*.*')), ('doc/_api', glob('doc/html/_api/*.*')), ], classifiers=[ 'Development Status :: 1 - Planning', 'Intended Audience :: Developers', 'License :: OSI Approved :: BSD License', 'Operating System :: Microsoft :: Windows', 'Programming Language :: Python :: 2.7', ], # see classifiers http://pypi.python.org/pypi?:action=list_classifiers ) config.update(dict( author='Jonathan Hartley', author_email='[email protected]', url='http://bitbucket.org/tartley/gloopy', license='New BSD', ) ) if '--verbose' in sys.argv: pprint(config) setup(**config) if __name__ == '__main__': main()

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• Efficient list compacting

  - by Patrik

  Suppose you have a list of unsigned ints. Suppose some elements are equal to 0 and you want to push them back. Currently I use this code (list is a pointer to a list of unsigned ints of size n for (i = 0; i < n; ++i) { if (list[i]) continue; int j; for (j = i + 1; j < n && !list[j]; ++j); int z; for (z = j + 1; z < n && list[z]; ++z); if (j == n) break; memmove(&(list[i]), &(list[j]), sizeof(unsigned int) * (z - j))); int s = z - j + i; for(j = s; j < z; ++j) list[j] = 0; i = s - 1; } Can you think of a more efficient way to perform this task? The snippet is purely theoretical, in the production code, each element of list is a 64 bytes struct EDIT: I'll post my solution. Many thanks to Jonathan Leffler. void RemoveDeadParticles(int * list, int * n) { int i, j = *n - 1; for (; j >= 0 && list[j] == 0; --j); for (i = 0; i < j; ++i) { if (list[i]) continue; memcpy(&(list[i]), &(list[j]), sizeof(int)); list[j] = 0; for (; j >= 0 && list[j] == 0; --j); if (i == j) break; } *n = i + 1; }

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• "Randomly" occurring errors...

  - by ClarkeyBoy

  Hi, My website has a setup whereby when the application starts a module called SiteContent is "created". This runs a clearup function which basically deletes any irrelevant data from the database, in case any has been left in there from previously run functions. The module has instances of Manager classes - namely RangeManager, CollectionManager, DesignManager. There are others but I will just use these as an example. Each Manager class contains an array of items - items may be of type Range, Collection or Design, whichever one is relevant. Data for each range is then read into an instance of Range, Collection or Design. I know this is basically duplicating data - not very efficient but its my final year project at the moment so I can always change it to use Linq or something similar later, when I am not pressured by the one month deadline. I have a form which, on clicking the Save button, saves data by calling SiteContent.RangeManager.Create(vars) or SiteContent.RangeManager.Update(Range As Range, vars) (or the equivalent for other manager classes, whichever one happens to be relevant). These functions call a stored procedure to insert or update in the relevant table. Classes Range, Collection and Design all have attributes such as Name, Description, Display and several others. When the Create or Update function is called, the Manager loops through all the other items to check if an item with the same name already exists. The Update function ensures that it does not compare the item being updated to itself. A custom exception (ItemAlreadyExistsException) is thrown if another item with the same name is found. For some weird reason, if I go into a Range, Collection or Design in edit mode, change something and try to update it, it occasionally doesnt update the item. When I say occasionally I mean every 3 - 4 page loads, sometimes more. I see absolutely no pattern in when or why it occurs. I have a try-catch statement which catches ItemAlreadyExistsException, and outputs "An item with this name already exists" when caught. Occasionally it will output this; other times it will not. Does anyone have any idea why this could happen? Maybe a mistake which someone has made and solved before? I used to have regular expressions in place that the names were compared to - I believe it was [a-zA-Z]{1, 100} (between 1 and 100 lower- or upper-case characters). For some reason the customer who I am developing the site for used to get errors saying its not in the correct format. Yet he could try the same text 5 minutes later and it would work fine. I am thinking this could well be the same problem, since both problems occur at random. Many thanks in advance. Regards, Richard Clarke Edit: After much time spent narrowing down the code, I have decided to wait till my brother, who has been a programmer for at least 8 years more than I have, to come down over Easter and get him to have a look at it. If he cant solve it then I will zip the files up and put them somewhere for people to access and have a go at. I narrowed it down literally to the minimum number of files possible, and it still occurs. It seems to be about every 10th time. Having said that, I force the manager classes to refresh every 10 page loads or 5 minutes (whichever one is sooner). I may look into this - this could be causing a problem. Basically each Manager contains an array of an object. This array is populated using data from the database. The Update function takes an instance of the item and the new values to be set for the object. If it happens to be a page load where the array is reset (ie the data is loaded freshly from the database) then the object instance with the same ID wont be the same instance as the one being passed in. This explains the fact that it throws an ItemAlreadyExistsException now and then. It all makes sense now the more I think about it. If I were to pass in the ID of the object to be altered, rather than the object itself, then it should work perfectly. I will answer the question if I solve it..

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• Listing common SQL Code Smells.

  - by Phil Factor

  Once you’ve done a number of SQL Code-reviews, you’ll know those signs in the code that all might not be well. These ’Code Smells’ are coding styles that don’t directly cause a bug, but are indicators that all is not well with the code. . Kent Beck and Massimo Arnoldi seem to have coined the phrase in the "OnceAndOnlyOnce" page of www.C2.com, where Kent also said that code "wants to be simple". Bad Smells in Code was an essay by Kent Beck and Martin Fowler, published as Chapter 3 of the book ‘Refactoring: Improving the Design of Existing Code’ (ISBN 978-0201485677) Although there are generic code-smells, SQL has its own particular coding habits that will alert the programmer to the need to re-factor what has been written. See Exploring Smelly Code   and Code Deodorants for Code Smells by Nick Harrison for a grounding in Code Smells in C# I’ve always been tempted by the idea of automating a preliminary code-review for SQL. It would be so useful to trawl through code and pick up the various problems, much like the classic ‘Lint’ did for C, and how the Code Metrics plug-in for .NET Reflector by Jonathan 'Peli' de Halleux is used for finding Code Smells in .NET code. The problem is that few of the standard procedural code smells are relevant to SQL, and we need an agreed list of code smells. Merrilll Aldrich made a grand start last year in his blog Top 10 T-SQL Code Smells.However, I'd like to make a start by discovering if there is a general opinion amongst Database developers what the most important SQL Smells are. One can be a bit defensive about code smells. I will cheerfully write very long stored procedures, even though they are frowned on. I’ll use dynamic SQL occasionally. You can only use them as an aid for your own judgment and it is fine to ‘sign them off’ as being appropriate in particular circumstances. Also, whole classes of ‘code smells’ may be irrelevant for a particular database. The use of proprietary SQL, for example, is only a ‘code smell’ if there is a chance that the database will have to be ported to another RDBMS. The use of dynamic SQL is a risk only with certain security models. As the saying goes,  a CodeSmell is a hint of possible bad practice to a pragmatist, but a sure sign of bad practice to a purist. Plamen Ratchev’s wonderful article Ten Common SQL Programming Mistakes lists some of these ‘code smells’ along with out-and-out mistakes, but there are more. The use of nested transactions, for example, isn’t entirely incorrect, even though the database engine ignores all but the outermost: but it does flag up the possibility that the programmer thinks that nested transactions are supported. If anything requires some sort of general agreement, the definition of code smells is one. I’m therefore going to make this Blog ‘dynamic, in that, if anyone twitters a suggestion with a #SQLCodeSmells tag (or sends me a twitter) I’ll update the list here. If you add a comment to the blog with a suggestion of what should be added or removed, I’ll do my best to oblige. In other words, I’ll try to keep this blog up to date. The name against each 'smell' is the name of the person who Twittered me, commented about or who has written about the 'smell'. it does not imply that they were the first ever to think of the smell! Use of deprecated syntax such as *= (Dave Howard) Denormalisation that requires the shredding of the contents of columns. (Merrill Aldrich) Contrived interfaces Use of deprecated datatypes such as TEXT/NTEXT (Dave Howard) Datatype mis-matches in predicates that rely on implicit conversion.(Plamen Ratchev) Using Correlated subqueries instead of a join   (Dave_Levy/ Plamen Ratchev) The use of Hints in queries, especially NOLOCK (Dave Howard /Mike Reigler) Few or No comments. Use of functions in a WHERE clause. (Anil Das) Overuse of scalar UDFs (Dave Howard, Plamen Ratchev) Excessive ‘overloading’ of routines. The use of Exec xp_cmdShell (Merrill Aldrich) Excessive use of brackets. (Dave Levy) Lack of the use of a semicolon to terminate statements Use of non-SARGable functions on indexed columns in predicates (Plamen Ratchev) Duplicated code, or strikingly similar code. Misuse of SELECT * (Plamen Ratchev) Overuse of Cursors (Everyone. Special mention to Dave Levy & Adrian Hills) Overuse of CLR routines when not necessary (Sam Stange) Same column name in different tables with different datatypes. (Ian Stirk) Use of ‘broken’ functions such as ‘ISNUMERIC’ without additional checks. Excessive use of the WHILE loop (Merrill Aldrich) INSERT ... EXEC (Merrill Aldrich) The use of stored procedures where a view is sufficient (Merrill Aldrich) Not using two-part object names (Merrill Aldrich) Using INSERT INTO without specifying the columns and their order (Merrill Aldrich) Full outer joins even when they are not needed. (Plamen Ratchev) Huge stored procedures (hundreds/thousands of lines). Stored procedures that can produce different columns, or order of columns in their results, depending on the inputs. Code that is never used. Complex and nested conditionals WHILE (not done) loops without an error exit. Variable name same as the Datatype Vague identifiers. Storing complex data  or list in a character map, bitmap or XML field User procedures with sp_ prefix (Aaron Bertrand)Views that reference views that reference views that reference views (Aaron Bertrand) Inappropriate use of sql_variant (Neil Hambly) Errors with identity scope using SCOPE_IDENTITY @@IDENTITY or IDENT_CURRENT (Neil Hambly, Aaron Bertrand) Schemas that involve multiple dated copies of the same table instead of partitions (Matt Whitfield-Atlantis UK) Scalar UDFs that do data lookups (poor man's join) (Matt Whitfield-Atlantis UK) Code that allows SQL Injection (Mladen Prajdic) Tables without clustered indexes (Matt Whitfield-Atlantis UK) Use of "SELECT DISTINCT" to mask a join problem (Nick Harrison) Multiple stored procedures with nearly identical implementation. (Nick Harrison) Excessive column aliasing may point to a problem or it could be a mapping implementation. (Nick Harrison) Joining "too many" tables in a query. (Nick Harrison) Stored procedure returning more than one record set. (Nick Harrison) A NOT LIKE condition (Nick Harrison) excessive "OR" conditions. (Nick Harrison) User procedures with sp_ prefix (Aaron Bertrand) Views that reference views that reference views that reference views (Aaron Bertrand) sp_OACreate or anything related to it (Bill Fellows) Prefixing names with tbl_, vw_, fn_, and usp_ ('tibbling') (Jeremiah Peschka) Aliases that go a,b,c,d,e... (Dave Levy/Diane McNurlan) Overweight Queries (e.g. 4 inner joins, 8 left joins, 4 derived tables, 10 subqueries, 8 clustered GUIDs, 2 UDFs, 6 case statements = 1 query) (Robert L Davis) Order by 3,2 (Dave Levy) MultiStatement Table functions which are then filtered 'Sel * from Udf() where Udf.Col = Something' (Dave Ballantyne) running a SQL 2008 system in SQL 2000 compatibility mode(John Stafford)

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• Fragmented Log files could be slowing down your database

  - by Fatherjack

  Something that is sometimes forgotten by a lot of DBAs is the fact that database log files get fragmented in the same way that you get fragmentation in a data file. The cause is very different but the effect is the same – too much effort reading and writing data. Data files get fragmented as data is changed through normal system activity, INSERTs, UPDATEs and DELETEs cause fragmentation and most experienced DBAs are monitoring their indexes for fragmentation and dealing with it accordingly. However, you don’t hear about so many working on their log files. How can a log file get fragmented? I’m glad you asked. When you create a database there are at least two files created on the disk storage; an mdf for the data and an ldf for the log file (you can also have ndf files for extra data storage but that’s off topic for now). It is wholly possible to have more than one log file but in most cases there is little point in creating more than one as the log file is written to in a ‘wrap-around’ method (more on that later). When a log file is created at the time that a database is created the file is actually sub divided into a number of virtual log files (VLFs). The number and size of these VLFs depends on the size chosen for the log file. VLFs are also created in the space added to a log file when a log file growth event takes place. Do you have your log files set to auto grow? Then you have potentially been introducing many VLFs into your log file. Let’s get to see how many VLFs we have in a brand new database. USE master GO CREATE DATABASE VLF_Test ON ( NAME = VLF_Test, FILENAME = 'C:\Program Files\Microsoft SQL Server\MSSQL10.ROCK_2008\MSSQL\DATA\VLF_Test.mdf', SIZE = 100, MAXSIZE = 500, FILEGROWTH = 50 ) LOG ON ( NAME = VLF_Test_Log, FILENAME = 'C:\Program Files\Microsoft SQL Server\MSSQL10.ROCK_2008\MSSQL\DATA\VLF_Test_log.ldf', SIZE = 5MB, MAXSIZE = 250MB, FILEGROWTH = 5MB ); go USE VLF_Test go DBCC LOGINFO; The results of this are firstly a new database is created with specified files sizes and the the DBCC LOGINFO results are returned to the script editor. The DBCC LOGINFO results have plenty of interesting information in them but lets first note there are 4 rows of information, this relates to the fact that 4 VLFs have been created in the log file. The values in the FileSize column are the sizes of each VLF in bytes, you will see that the last one to be created is slightly larger than the others. So, a 5MB log file has 4 VLFs of roughly 1.25 MB. Lets alter the CREATE DATABASE script to create a log file that’s a bit bigger and see what happens. Alter the code above so that the log file details are replaced by LOG ON ( NAME = VLF_Test_Log, FILENAME = 'C:\Program Files\Microsoft SQL Server\MSSQL10.ROCK_2008\MSSQL\DATA\VLF_Test_log.ldf', SIZE = 1GB, MAXSIZE = 25GB, FILEGROWTH = 1GB ); With a bigger log file specified we get more VLFs What if we make it bigger again? LOG ON ( NAME = VLF_Test_Log, FILENAME = 'C:\Program Files\Microsoft SQL Server\MSSQL10.ROCK_2008\MSSQL\DATA\VLF_Test_log.ldf', SIZE = 5GB, MAXSIZE = 250GB, FILEGROWTH = 5GB ); This time we see more VLFs are created within our log file. We now have our 5GB log file comprised of 16 files of 320MB each. In fact these sizes fall into all the ranges that control the VLF creation criteria – what a coincidence! The rules that are followed when a log file is created or has it’s size increased are pretty basic. If the file growth is lower than 64MB then 4 VLFs are created If the growth is between 64MB and 1GB then 8 VLFs are created If the growth is greater than 1GB then 16 VLFs are created. Now the potential for chaos comes if the default values and settings for log file growth are used. By default a database log file gets a 1MB log file with unlimited growth in steps of 10%. The database we just created is 6 MB, let’s add some data and see what happens. USE vlf_test go -- we need somewhere to put the data so, a table is in order IF OBJECT_ID('A_Table') IS NOT NULL DROP TABLE A_Table go CREATE TABLE A_Table ( Col_A int IDENTITY, Col_B CHAR(8000) ) GO -- Let's check the state of the log file -- 4 VLFs found EXECUTE ('DBCC LOGINFO'); go -- We can go ahead and insert some data and then check the state of the log file again INSERT A_Table (col_b) SELECT TOP 500 REPLICATE('a',2000) FROM sys.columns AS sc, sys.columns AS sc2 GO -- insert 500 rows and we get 22 VLFs EXECUTE ('DBCC LOGINFO'); go -- Let's insert more rows INSERT A_Table (col_b) SELECT TOP 2000 REPLICATE('a',2000) FROM sys.columns AS sc, sys.columns AS sc2 GO 10 -- insert 2000 rows, in 10 batches and we suddenly have 107 VLFs EXECUTE ('DBCC LOGINFO'); Well, that escalated quickly! Our log file is split, internally, into 107 fragments after a few thousand inserts. The same happens with any logged transactions, I just chose to illustrate this with INSERTs. Having too many VLFs can cause performance degradation at times of database start up, log backup and log restore operations so it’s well worth keeping a check on this property. How do we prevent excessive VLF creation? Creating the database with larger files and also with larger growth steps and actively choosing to grow your databases rather than leaving it to the Auto Grow event can make sure that the growths are made with a size that is optimal. How do we resolve a situation of a database with too many VLFs? This process needs to be done when the database is under little or no stress so that you don’t affect system users. The steps are: BACKUP LOG YourDBName TO YourBackupDestinationOfChoice Shrink the log file to its smallest possible size DBCC SHRINKFILE(FileNameOfTLogHere, TRUNCATEONLY) * Re-size the log file to the size you want it to, taking in to account your expected needs for the coming months or year. ALTER DATABASE YourDBName MODIFY FILE ( NAME = FileNameOfTLogHere, SIZE = TheSizeYouWantItToBeIn_MB) * – If you don’t know the file name of your log file then run sp_helpfile while you are connected to the database that you want to work on and you will get the details you need. The resize step can take quite a while This is already detailed far better than I can explain it by Kimberley Tripp in her blog 8-Steps-to-better-Transaction-Log-throughput.aspx. The result of this will be a log file with a VLF count according to the bullet list above. Knowing when VLFs are being created By complete coincidence while I have been writing this blog (it’s been quite some time from it’s inception to going live) Jonathan Kehayias from SQLSkills.com has written a great article on how to track database file growth using Event Notifications and Service Broker. I strongly recommend taking a look at it as this is going to catch any sneaky auto grows that take place and let you know about them right away. Hassle free monitoring of VLFs If you are lucky or wise enough to be using SQL Monitor or another monitoring tool that let’s you write your own custom metrics then you can keep an eye on this very easily. There is a custom metric for VLFs (written by Stuart Ainsworth) already on the site and there are some others there are very useful so take a moment or two to look around while you are there. Resources MSDN – http://msdn.microsoft.com/en-us/library/ms179355(v=sql.105).aspx Kimberly Tripp from SQLSkills.com – http://www.sqlskills.com/BLOGS/KIMBERLY/post/8-Steps-to-better-Transaction-Log-throughput.aspx Thomas LaRock at Simple-Talk.com – http://www.simple-talk.com/sql/database-administration/monitoring-sql-server-virtual-log-file-fragmentation/ Disclosure I am a Friend of Red Gate. This means that I am more than likely to say good things about Red Gate DBA and Developer tools. No matter how awesome I make them sound, take the time to compare them with other products before you contact the Red Gate sales team to make your order.

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• Try a sample: Using the counter predicate for event sampling

  - by extended_events

  Extended Events offers a rich filtering mechanism, called predicates, that allows you to reduce the number of events you collect by specifying criteria that will be applied during event collection. (You can find more information about predicates in Using SQL Server 2008 Extended Events (by Jonathan Kehayias)) By evaluating predicates early in the event firing sequence we can reduce the performance impact of collecting events by stopping event collection when the criteria are not met. You can specify predicates on both event fields and on a special object called a predicate source. Predicate sources are similar to action in that they typically are related to some type of global information available from the server. You will find that many of the actions available in Extended Events have equivalent predicate sources, but actions and predicates sources are not the same thing. Applying predicates, whether on a field or predicate source, is very similar to what you are used to in T-SQL in terms of how they work; you pick some field/source and compare it to a value, for example, session_id = 52. There is one predicate source that merits special attention though, not just for its special use, but for how the order of predicate evaluation impacts the behavior you see. I’m referring to the counter predicate source. The counter predicate source gives you a way to sample a subset of events that otherwise meet the criteria of the predicate; for example you could collect every other event, or only every tenth event. Simple CountingThe counter predicate source works by creating an in memory counter that increments every time the predicate statement is evaluated. Here is a simple example with my favorite event, sql_statement_completed, that only collects the second statement that is run. (OK, that’s not much of a sample, but this is for demonstration purposes. Here is the session definition: CREATE EVENT SESSION counter_test ON SERVERADD EVENT sqlserver.sql_statement_completed    (ACTION (sqlserver.sql_text)    WHERE package0.counter = 2)ADD TARGET package0.ring_bufferWITH (MAX_DISPATCH_LATENCY = 1 SECONDS) You can find general information about the session DDL syntax in BOL and from Pedro’s post Introduction to Extended Events. The important part here is the WHERE statement that defines that I only what the event where package0.count = 2; in other words, only the second instance of the event. Notice that I need to provide the package name along with the predicate source. You don’t need to provide the package name if you’re using event fields, only for predicate sources. Let’s say I run the following test queries: -- Run three statements to test the sessionSELECT 'This is the first statement'GOSELECT 'This is the second statement'GOSELECT 'This is the third statement';GO Once you return the event data from the ring buffer and parse the XML (see my earlier post on reading event data) you should see something like this: event_name sql_text sql_statement_completed SELECT ‘This is the second statement’ You can see that only the second statement from the test was actually collected. (Feel free to try this yourself. Check out what happens if you remove the WHERE statement from your session. Go ahead, I’ll wait.) Percentage Sampling OK, so that wasn’t particularly interesting, but you can probably see that this could be interesting, for example, lets say I need a 25% sample of the statements executed on my server for some type of QA analysis, that might be more interesting than just the second statement. All comparisons of predicates are handled using an object called a predicate comparator; the simple comparisons such as equals, greater than, etc. are mapped to the common mathematical symbols you know and love (eg. = and >), but to do the less common comparisons you will need to use the predicate comparators directly. You would probably look to the MOD operation to do this type sampling; we would too, but we don’t call it MOD, we call it divides_by_uint64. This comparator evaluates whether one number is divisible by another with no remainder. The general syntax for using a predicate comparator is pred_comp(field, value), field is always first and value is always second. So lets take a look at how the session changes to answer our new question of 25% sampling: CREATE EVENT SESSION counter_test_25 ON SERVERADD EVENT sqlserver.sql_statement_completed    (ACTION (sqlserver.sql_text)    WHERE package0.divides_by_uint64(package0.counter,4))ADD TARGET package0.ring_bufferWITH (MAX_DISPATCH_LATENCY = 1 SECONDS)GO Here I’ve replaced the simple equivalency check with the divides_by_uint64 comparator to check if the counter is evenly divisible by 4, which gives us back every fourth record. I’ll leave it as an exercise for the reader to test this session. Why order matters I indicated at the start of this post that order matters when it comes to the counter predicate – it does. Like most other predicate systems, Extended Events evaluates the predicate statement from left to right; as soon as the predicate statement is proven false we abandon evaluation of the remainder of the statement. The counter predicate source is only incremented when it is evaluated so whether or not the counter is incremented will depend on where it is in the predicate statement and whether a previous criteria made the predicate false or not. Here is a generic example: Pred1: (WHERE statement_1 AND package0.counter = 2)Pred2: (WHERE package0.counter = 2 AND statement_1) Let’s say I cause a number of events as follows and examine what happens to the counter predicate source. Iteration Statement Pred1 Counter Pred2 Counter A Not statement_1 0 1 B statement_1 1 2 C Not statement_1 1 3 D statement_1 2 4 As you can see, in the case of Pred1, statement_1 is evaluated first, when it fails (A & C) predicate evaluation is stopped and the counter is not incremented. With Pred2 the counter is evaluated first, so it is incremented on every iteration of the event and the remaining parts of the predicate are then evaluated. In this example, Pred1 would return an event for D while Pred2 would return an event for B. But wait, there is an interesting side-effect here; consider Pred2 if I had run my statements in the following order: Not statement_1 Not statement_1 statement_1 statement_1 In this case I would never get an event back from the system because the point at which counter=2, the rest of the predicate evaluates as false so the event is not returned. If you’re using the counter target for sampling and you’re not getting the expected events, or any events, check the order of the predicate criteria. As a general rule I’d suggest that the counter criteria should be the last element of your predicate statement since that will assure that your sampling rate will apply to the set of event records defined by the rest of your predicate. Aside: I’m interested in hearing about uses for putting the counter predicate criteria earlier in the predicate statement. If you have one, post it in a comment to share with the class. - Mike Share this post: email it! | bookmark it! | digg it! | reddit! | kick it! | live it!

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• Workshops, online content show how Oracle infuses simplicity, mobility, extensibility into user experience

  - by mvaughan

  By Kathy Miedema & Misha Vaughan, Oracle Applications User Experience Oracle has made a huge investment into the user experience of its many different software product families, and recent releases showcase big changes and features that aim to promote end user engagement and efficiency by streamlining navigation and simplifying the user interface. But making Oracle’s enterprise software great-looking and usable doesn’t stop when Oracle products go out the door. The Applications User Experience (UX) team recognizes that our customers may need to customize software to fit their work processes. And that’s why we provide tools such as user experience design patterns to help you maintain the Oracle user experience as you tailor your application to fit your business needs. Often, however, customers may need some context around user experience. How has the Oracle user experience been designed and constructed? Why is a good user experience important for users? How does understanding what goes into the user experience benefit the people who purchase the software for users? There’s a short answer to these questions, and you can read about it on Usable Apps. But truly understanding Oracle’s investment and seeing how it applies across product families occasionally requires a deeper dive into the Oracle user experience, especially if you’re an influencer or decision-maker about Oracle products. To help frame these decisions, the Communications & Outreach team has developed several targeted workshops that explore what Oracle means when it talks about user experience, and provides a roadmap into where the Oracle user experience is going. These workshops require non-disclosure agreements, and have been delivered to Oracle sales folks, Oracle partners, Oracle ACE Directors and ACEs, and a few customers. Some of these audience members have been developers or have a technical background; just as many did not. Here’s a breakdown of the kind of training you can get around the Oracle user experience from the OAUX Communications & Outreach team.For Partners: George Papazzian, Principal, Naviscent with Joyce Ohgi, Oracle Oracle Fusion Applications HCM Pre-Sales Seminar:  In concert with Worldwide Alliances  and  Channels under Applications Partner Enablement Director Jonathan Vinoskey’s guidance, the Applications User Experience team delivers a two-day workshop.  Day one focuses on Oracle Fusion Applications HCM and pre-sales strategy, and Day two focuses on positioning and leveraging Oracle’s investment in the Oracle Fusion Applications user experience.  The next workshops will occur on the following dates: December 4-5, 2013 @ Manchester, UK January 29-30, 2014 @ Reston, Virginia February 2014 @ Guadalajara, Mexico (email: Shannon Whiteman) March 11-12, 2014 @ Dubai, United Arab Emirates April 1-2, 2014 @ Chicago, Illinois Partner Advisory Board: A two-day board meeting in the U.S. and U.K. to discuss four main user experience areas for Oracle Fusion Applications: simplicity, visualization & analytics, mobility, & futures. This event is limited to Oracle Diamond Partners, UX bloggers, and key UX influencers and requires legal documentation.  We will be talking about the Oracle applications UX strategy and roadmap. Partner Implementation Training on User Interface: How to Build Great-Looking, Usable Apps:  In this two-day, hands-on workshop built around Oracle’s Application Development Framework, learn how to build desktop and mobile user interfaces and mobile user interfaces based on Oracle’s experience with Fusion Applications. This workshop is for partners with a technology background who are looking for ways to tailor Fusion Applications using ADF, or have built their own custom solutions using ADF. It includes an introduction to UX design patterns and provides tools to build usability-tested UX designs. Nov 5-6, 2013 @ Redwood Shores, CA, USA January 28-29th, 2014 @ Reston, Virginia, USA February 25-26, 2014 @ Guadalajara, Mexico March 9-10, 2014 @ Dubai, United Arab Emirates To register, contact [email protected] Simplified UI Customization & Extensibility:  Pilot workshop:  We will be reviewing the proposed content for communicating the user experience tool kit available with the next release of Oracle Fusion Applications.  Our core focus will be on what toolkit components our system implementors and independent software vendors will need to respond to customer demand, whether they are extending Fusion Applications, or building custom applications, that will need to leverage the simplified UI. Dec 11th, 2013 @ Reading, UK For information: contact [email protected] Private lab tour and demos: Interested in seeing what’s going on in the Apps UX Labs?  If you are headed to the San Francisco Bay Area, let us know. We can arrange a spin through our usability labs at headquarters. OAUX Expo: This open-house forum gives partners a look at what the UX team is working on, and showcases the next-generation user experiences in a demo environment where attendees can see and touch the applications. UX Direct: Use the same methods that Oracle uses to develop its own user experiences. We help you define your users and their needs, and then provide direction on how to tailor the best user experience you can for them. For CustomersAngela Johnston, Gozel Aamoth, Teena Singh, and Yen Chan, Oracle Lab tours: See demos of soon-to-be-released products, and take a spin on usability research equipment such as our eye-tracker. Watch this video to get an idea of what you’ll see. Get our newsletter: Learn about newly released products and see where you can meet us at user group conferences. Participate in a feedback session: Join a focus group or customer feedback session to get an early look at user experience designs for the next generation of software, and provide your thoughts on how well it will work. Join the OUAB: The Oracle Usability Advisory Board meets several times a year to discuss trends in the workforce and provide direction on user experience designs. UX Direct: Use the same methods that Oracle uses to develop its own user experiences. We help you define your users and their needs, and then provide direction on how to tailor the best user experience you can for them. For Developers (customers, partners, and consultants): Plinio Arbizu, SP Solutions, Richard Bingham, Oracle, Balaji Kamepalli, EiSTechnoogies, Praveen Pillalamarri, EiSTechnologies How to Build Great-Looking, Usable Apps: This workshop is for attendees with a strong technology background who are looking for ways to tailor customer software using ADF. It includes an introduction to UX design patterns and provides tools to build usability-tested UX designs.  See above for dates and times. UX design patterns web site: Cut the length of your project down by months. Use these patterns to build out the task flow you need to develop for your users. The patterns have already been usability-tested and represent the best practices that the Oracle UX research team has found in its studies. UX Direct: Use the same methods that Oracle uses to develop its own user experiences. We help you define your users and their needs, and then provide direction on how to tailor the best user experience you can for them. For Oracle Sales Mike Klein, Jeremy Ashley, Brent White, Oracle Contact your local sales person for more information about the Oracle user experience and the training available from the Applications User Experience Communications & Outreach team. See customer-friendly user experience collateral ranging from the new simplified UI in Oracle Fusion Applications Release 7, to E-Business Suite user experience highlights, to Siebel, PeopleSoft, and JD Edwards user experience highlights.   Receive access to the same pre-sales and implementation training we provide to partners. For Oracle Sales only: Oracle-only training on the Oracle Fusion Applications UX Innovation Sales Kit.

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• HTML E-Mail as fileattachment

  - by johnny

  I have a Problem with Outlook 2010. I sent an E-Mail with a Contactform with this Code: $message = ' <html> <head> <title>Anfrage ('.$cfg->get('global.page.title').')</title> <style type="text/css"> body { background:#FFFFFF; color:#000000; } #tbl td { background:#F0F0F0; vertical-align:top; } #tbl2 td { background:#E0E0E0; vertical-align:top; } </style> </head> <body> <p>Mail von der Webseite '.$cfg->get('global.page.title').'</p> <table id="tbl"> <tr> <td>Absender</td> <td>'.htmlspecialchars($_POST['name']).' ('.htmlspecialchars(trim($_POST['email'])).')</td> </tr> <tr id="tbl2"> <td>Betreff:</td> <td>'.htmlspecialchars($_POST["topic"]).'</td> </tr> <tr> <td>Nachricht:</td> <td>'.nl2br(htmlspecialchars($_POST["message"])).'</td> </tr> </table> </body> </html>'; $absender = $_POST['name'].' <'.$_POST['email'].'>'; $header = "From: $absender\n"; $header .= "Reply-To: $absender\n"; $header .= "X-Mailer: PHP/" . phpversion(). "\n"; $header .= "X-Sender-IP: " . $_SERVER["REMOTE_ADDR"] . "\n"; $header .= "Content-Type: text/html; Charset=utf-8"; $send_mail = mail($cfg->get('contact.toMailAdress'), "Anfrage (".$cfg->get('global.page.title').")", $message, $header); //$send_mail = mail("jonathan[email protected]", "Anfrage (".$cfg->get('global.page.title').")", $message, $header); $_SESSION['kontakt_form_time'] = time(); $tpl->assign("mail_sent", $send_mail); When I sent the email, doesn't shows the message. it generates a File named [NAME].h. The Message is in this File. How can I fix that, that the message shows in the E-Mail. Is this a Problem about the settings in Outlook?

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• CodePlex Daily Summary for Saturday, May 29, 2010

  CodePlex Daily Summary for Saturday, May 29, 2010New ProjectsASP.NET MVC Time Planner: ASP.NET MVC based time planner is example solution that introduces ASP.NET MVC, MSSQL AJAX and jQuery development.Blit Scripting Engine: Blit Scripting Engine provides developers using Microsofts XNA Framework the ability to implement a scripting solution to their games and other pro...Expression Evaluator: This is an article on how to build a basic expression evaluator. It can evaluate any numerical expression combined with trigonometric functions for...Log Analyzer: This project has the aim to help developers to see live log/trace from their application applying visual styles to the grabbed text.LParse: LParse is a monadic parser combinator library, similar to Haskell’s Parsec. It allows you create parsers on C# language. All parsers are first-clas...NeatHtml: NeatHtml™ is a highly-portable open source website component that displays untrusted content securely, efficiently, and accessibly. Untrusted conte...NeatUpload: The NeatUpload ™ ASP.NET component allows developers to stream uploaded files to storage (filesystem or database) and allows users to monitor uplo...NSoup: NSoup is a .NET port of the jsoup (http://jsoup.org) HTML parser and sanitizer originally written in Java. jsoup originally written by Jonathan He...Ordering: c# farm softwarephone7: Project for Windows Phone 7RestCall: A very simple library to make a simple REST call and deserialize to an object. It uses WCF REST Starter Kit and the .net serializer in: System.Runt...SCSM CSV Connector: CSV Connector allows you to specify a data file and mapping location and a scheuled interval in minutes. At each scheduled interval Service Manage...Silverlight Adorner Control: An Adorner is a custom FrameworkElement that is bound to a FrameworkElement and displays information about that element 'above' the element without...Simple Stupid Tools: Simple Stupid ToolsSQScriptRunner: Simple Quick Script Runner allows an administrator to run T-SQL Scripts against one or more servers with common characteristics. For example, an m...ssisassembly: ssisassemblySSRS Report RoboCopy: a tools used to pass a report from a server to anotherTeam Foundation Server Explorer: A standalone Team Foundation Server explorer that can be used to view and manage source files.New Releases(SocketCoder) Full Silverlight Web Video/Voice Conferencing: SocketCoderWebConferencingSystem_Compiled: Installing The Server: 1- before you start you should allow the SocketCoderWCService.MainService.exe service to use the TCP ports from 4528 to 4532...ASP.NET MVC Time Planner: MVC Time Planner - v0.0.1.0: First public alpha of MVC Time Planner is now available. I got a lot of letters from my ASP.NET blog readers who are interested in this example sol...AvalonDock: AvalonDock 1.3.3384: Welcome to AvalonDock 1.3 This is the new version of AvalonDock targetting .NET 4 These are the main features that are included: - Target Microso...Blit Scripting Engine: Blit Scripting Engine 1.0: This marks the initial release of the Blit Scripting Engine. It provides the ability to compile scripts to an assembly, load pre-compiled assemblie...Community Forums NNTP bridge: Community Forums NNTP Bridge V12: Release of the Community Forums NNTP Bridge to access the social and anwsers MS forums with a single, open source NNTP bridge. This release has add...Community Forums NNTP bridge: Community Forums NNTP Bridge V13: Release of the Community Forums NNTP Bridge to access the social and anwsers MS forums with a single, open source NNTP bridge. This release has add...CSharp Intellisense: V2.4: bug fix: Pascal Casing, Single Selection and other selection errorsExpression Evaluator: Expression Evaluator - Visual Studio 2010: Visual Studio 2010 VersionFacebook Graph Toolkit: Preview 2: Preview 2 updates the source to be much more like the Facebook PHP-SDK. Additionally, the code has been updated to follow StyleCop framework rules....Facebook Graph Toolkit: Preview 3: Rest API now working although not fully tested. Removed JsonObject and JsonArray custom dynamic objects in favor of standard ExpandoObject and List...Free Silverlight & WPF Chart Control - Visifire: Visifire SL and WPF Charts v3.1.1 beta Released: Hi, Today we are releasing the two most awaited features i.e, Logarithmic axis and auto update of y-axis while Scrolling and Zooming. * Logar...Free Silverlight & WPF Chart Control - Visifire: Visifire SL and WPF Charts v3.5.4 beta Released: Hi, Today we are releasing the two most awaited features i.e, Logarithmic axis and auto update of y-axis while Scrolling and Zooming. Logarithmic...Fulcrum: Fulcrum 1.0: Initial release.Git Source Control Provider: V 0.3: V 0.3 Add automatic status refresh when files in solution folder changedIBCSharp: IBCSharp 1.04: What IBCSharp 1.04.zip unzips to: http://i50.tinypic.com/205qofl.png IBCSharp Change Log 1.04 - 5/28/2010 Updated IBClient.dll to IB API version...MapWindow6: MapWindow 6.0 May 28 2010: This shifts the projection library to System.Spatial.Projections instead of MWProj4. This also fixes a meter/feet conversion error.Microsoft Health Common User Interface: Release 8.2.51.000: This is version 8.2 of the Microsoft® Health Common User Interface Control Toolkit. This release includes code updates to controls as listed below....NeatHtml: NeatHtml-trunk.221: Adds support for Internet Explorer Mobile 6.NeatUpload: NeatUpload-1.3.25: Fixes the following bugs: SWFUpload.swf could not be served by a CDN because it was embedded without setting allowScriptAccess="always". NeatUpl...NSoup: NSoup 0.1: Initial port release. Corresponds to jsoup version 0.3.1.Numina Application/Security Framework: Numina.Framework Core 53265: Visit http://framework.numina.net to help get you started.Nuntio Content: Nuntio Content 4.2.0: This upgrades MagicContent instances to the latest version that is now called NuntioContent. While this release is quite stable it is still marked ...patterns & practices: Composite WPF and Silverlight: ProjectLinker Source for VS2010 - May 2010: The ProjectLinker helps keep the source for two projects in sync by automatically creating a linked file in one project as files are added in anoth...phone7: Prism for WP7: This the first version of prism for wp7SCSM CSV Connector: SCSM CSV Connector Version 0.1: Release Notes This is the first release of the SCSM CSV Connector solution. It is an 'alpha' release and has only been tested by the developers on ...Silverlight Adorner Control: 1.0: Initial releaseSilverlight Web Comic: Comic 1.1.1: Comic Beta with functionality to button newSilverlight Web Comic: Web Comic 1.1: This version has a little implementation no visible about the future versions, options to new, save, and load. The next version has a better review...Simple.NET: Simple.Mocking 1.0.0.6: Initial version of a new mocking framework for .NET Revision 1: Expect.AnyInocationOn<T>(T target) changed to Expect.AnyInocationOn(object target...Sonic.Net: Sonic.Net v1.0.1 For Unity 2.0: This Version is a port to VS2010 of the codebase with support for unity 2.0. note: currently follows the xsd schema of the previous unity Configur...Squiggle - A Free open source Lan Messenger: Squiggle 1.0.2: v1.0 Release.Team Foundation Server Explorer: Beta 1: The first public beta release of the TFS Explorer.thinktecture WSCF.blue: WSCF.blue V1 Update (1.0.8): Bug fix release with the following fix: When an XmlArrayAttribute decorated member has IsNullable=false, and the List<T> or Collection option is s...VCC: Latest build, v2.1.30528.0: Automatic drop of latest buildVisual Studio 2010 AutoScroller Extension: AutoScroller v0.4: A Visual studio 2010 auto-scroller extension. Simply hold down your middle mouse button and drag the mouse in the direction you wish to scroll, fu...WatchersNET CKEditor™ Provider for DotNetNuke: CKEditor Provider 1.10.03: !!Whats New Added CKEditor 3.3 Revision 5542 changes Options: Default Toolbar Set to Full for Administrators Browser Window: Increased Size of ...Most Popular ProjectsRawrWBFS ManagerAJAX Control ToolkitMicrosoft SQL Server Product Samples: DatabaseSilverlight ToolkitWindows Presentation Foundation (WPF)patterns & practices – Enterprise LibraryMicrosoft SQL Server Community & SamplesPHPExcelASP.NETMost Active ProjectsAStar.netpatterns & practices – Enterprise LibraryBlogEngine.NETGMap.NET - Great Maps for Windows Forms & PresentationCommunity Forums NNTP bridgeRawrSqlServerExtensionsCustomer Portal Accelerator for Microsoft Dynamics CRMPAPpatterns & practices: Windows Azure Security Guidance

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• quick look at: dm_db_index_physical_stats

  - by fatherjack

  A quick look at the key data from this dmv that can help a DBA keep databases performing well and systems online as the users need them. When the dynamic management views relating to index statistics became available in SQL Server 2005 there was much hype about how they can help a DBA keep their servers running in better health than ever before. This particular view gives an insight into the physical health of the indexes present in a database. Whether they are use or unused, complete or missing some columns is irrelevant, this is simply the physical stats of all indexes; disabled indexes are ignored however. In it’s simplest form this dmv can be executed as:   The results from executing this contain a record for every index in every database but some of the columns will be NULL. The first parameter is there so that you can specify which database you want to gather index details on, rather than scan every database. Simply specifying DB_ID() in place of the first NULL achieves this. In order to avoid the NULLS, or more accurately, in order to choose when to have the NULLS you need to specify a value for the last parameter. It takes one of 4 values – DEFAULT, ‘SAMPLED’, ‘LIMITED’ or ‘DETAILED’. If you execute the dmv with each of these values you can see some interesting details in the times taken to complete each step. DECLARE @Start DATETIME DECLARE @First DATETIME DECLARE @Second DATETIME DECLARE @Third DATETIME DECLARE @Finish DATETIME SET @Start = GETDATE() SELECT * FROM [sys].[dm_db_index_physical_stats](DB_ID(), NULL, NULL, NULL, DEFAULT) AS ddips SET @First = GETDATE() SELECT * FROM [sys].[dm_db_index_physical_stats](DB_ID(), NULL, NULL, NULL, 'SAMPLED') AS ddips SET @Second = GETDATE() SELECT * FROM [sys].[dm_db_index_physical_stats](DB_ID(), NULL, NULL, NULL, 'LIMITED') AS ddips SET @Third = GETDATE() SELECT * FROM [sys].[dm_db_index_physical_stats](DB_ID(), NULL, NULL, NULL, 'DETAILED') AS ddips SET @Finish = GETDATE() SELECT DATEDIFF(ms, @Start, @First) AS [DEFAULT] , DATEDIFF(ms, @First, @Second) AS [SAMPLED] , DATEDIFF(ms, @Second, @Third) AS [LIMITED] , DATEDIFF(ms, @Third, @Finish) AS [DETAILED] Running this code will give you 4 result sets; DEFAULT will have 12 columns full of data and then NULLS in the remainder. SAMPLED will have 21 columns full of data. LIMITED will have 12 columns of data and the NULLS in the remainder. DETAILED will have 21 columns full of data. So, from this we can deduce that the DEFAULT value (the same one that is also applied when you query the view using a NULL parameter) is the same as using LIMITED. Viewing the final result set has some details that are worth noting: Running queries against this view takes significantly longer when using the SAMPLED and DETAILED values in the last parameter. The duration of the query is directly related to the size of the database you are working in so be careful running this on big databases unless you have tried it on a test server first. Let’s look at the data we get back with the DEFAULT value first of all and then progress to the extra information later. We know that the first parameter that we supply has to be a database id and for the purposes of this blog we will be providing that value with the DB_ID function. We could just as easily put a fixed value in there or a function such as DB_ID (‘AnyDatabaseName’). The first columns we get back are database_id and object_id. These are pretty explanatory and we can wrap those in some code to make things a little easier to read: SELECT DB_NAME([ddips].[database_id]) AS [DatabaseName] , OBJECT_NAME([ddips].[object_id]) AS [TableName] … FROM [sys].[dm_db_index_physical_stats](DB_ID(), NULL, NULL, NULL, NULL) AS ddips  gives us   SELECT DB_NAME([ddips].[database_id]) AS [DatabaseName] , OBJECT_NAME([ddips].[object_id]) AS [TableName], [i].[name] AS [IndexName] , ….. FROM [sys].[dm_db_index_physical_stats](DB_ID(), NULL, NULL, NULL, NULL) AS ddips INNER JOIN [sys].[indexes] AS i ON [ddips].[index_id] = [i].[index_id] AND [ddips].[object_id] = [i].[object_id]     These handily tie in with the next parameters in the query on the dmv. If you specify an object_id and an index_id in these then you get results limited to either the table or the specific index. Once again we can place a  function in here to make it easier to work with a specific table. eg. SELECT * FROM [sys].[dm_db_index_physical_stats] (DB_ID(), OBJECT_ID(‘AdventureWorks2008.Person.Address’) , 1, NULL, NULL) AS ddips   Note: Despite me showing that functions can be placed directly in the parameters for this dmv, best practice recommends that functions are not used directly in the function as it is possible that they will fail to return a valid object ID. To be certain of not passing invalid values to this function, and therefore setting an automated process off on the wrong path, declare variables for the OBJECT_IDs and once they have been validated, use them in the function: DECLARE @db_id SMALLINT; DECLARE @object_id INT; SET @db_id = DB_ID(N’AdventureWorks_2008′); SET @object_id = OBJECT_ID(N’AdventureWorks_2008.Person.Address’); IF @db_id IS NULL BEGINPRINT N’Invalid database’; ENDELSE IF @object_id IS NULL BEGINPRINT N’Invalid object’; ENDELSE BEGINSELECT * FROM sys.dm_db_index_physical_stats (@db_id, @object_id, NULL, NULL , ‘LIMITED’); END; GO In cases where the results of querying this dmv don’t have any effect on other processes (i.e. simply viewing the results in the SSMS results area)  then it will be noticed when the results are not consistent with the expected results and in the case of this blog this is the method I have used. So, now we can relate the values in these columns to something that we recognise in the database lets see what those other values in the dmv are all about. The next columns are: We’ll skip partition_number, index_type_desc, alloc_unit_type_desc, index_depth and index_level  as this is a quick look at the dmv and they are pretty self explanatory. The final columns revealed by querying this view in the DEFAULT mode are avg_fragmentation_in_percent. This is the amount that the index is logically fragmented. It will show NULL when the dmv is queried in SAMPLED mode. fragment_count. The number of pieces that the index is broken into. It will show NULL when the dmv is queried in SAMPLED mode. avg_fragment_size_in_pages. The average size, in pages, of a single fragment in the leaf level of the IN_ROW_DATA allocation unit. It will show NULL when the dmv is queried in SAMPLED mode. page_count. Total number of index or data pages in use. OK, so what does this give us? Well, there is an obvious correlation between fragment_count, page_count and avg_fragment_size-in_pages. We see that an index that takes up 27 pages and is in 3 fragments has an average fragment size of 9 pages (27/3=9). This means that for this index there are 3 separate places on the hard disk that SQL Server needs to locate and access to gather the data when it is requested by a DML query. If this index was bigger than 72KB then having it’s data in 3 pieces might not be too big an issue as each piece would have a significant piece of data to read and the speed of access would not be too poor. If the number of fragments increases then obviously the amount of data in each piece decreases and that means the amount of work for the disks to do in order to retrieve the data to satisfy the query increases and this would start to decrease performance. This information can be useful to keep in mind when considering the value in the avg_fragmentation_in_percent column. This is arrived at by an internal algorithm that gives a value to the logical fragmentation of the index taking into account the multiple files, type of allocation unit and the previously mentioned characteristics if index size (page_count) and fragment_count. Seeing an index with a high avg_fragmentation_in_percent value will be a call to action for a DBA that is investigating performance issues. It is possible that tables will have indexes that suffer from rapid increases in fragmentation as part of normal daily business and that regular defragmentation work will be needed to keep it in good order. In other cases indexes will rarely become fragmented and therefore not need rebuilding from one end of the year to another. Keeping this in mind DBAs need to use an ‘intelligent’ process that assesses key characteristics of an index and decides on the best, if any, defragmentation method to apply should be used. There is a simple example of this in the sample code found in the Books OnLine content for this dmv, in example D. There are also a couple of very popular solutions created by SQL Server MVPs Michelle Ufford and Ola Hallengren which I would wholly recommend that you review for much further detail on how to care for your SQL Server indexes. Right, let’s get back on track then. Querying the dmv with the fifth parameter value as ‘DETAILED’ takes longer because it goes through the index and refreshes all data from every level of the index. As this blog is only a quick look a we are going to skate right past ghost_record_count and version_ghost_record_count and discuss avg_page_space_used_in_percent, record_count, min_record_size_in_bytes, max_record_size_in_bytes and avg_record_size_in_bytes. We can see from the details below that there is a correlation between the columns marked. Column 1 (Page_Count) is the number of 8KB pages used by the index, column 2 is how full each page is (how much of the 8KB has actual data written on it), column 3 is how many records are recorded in the index and column 4 is the average size of each record. This approximates to: ((Col1*8) * 1024*(Col2/100))/Col3 = Col4*. avg_page_space_used_in_percent is an important column to review as this indicates how much of the disk that has been given over to the storage of the index actually has data on it. This value is affected by the value given for the FILL_FACTOR parameter when creating an index. avg_record_size_in_bytes is important as you can use it to get an idea of how many records are in each page and therefore in each fragment, thus reinforcing how important it is to keep fragmentation under control. min_record_size_in_bytes and max_record_size_in_bytes are exactly as their names set them out to be. A detail of the smallest and largest records in the index. Purely offered as a guide to the DBA to better understand the storage practices taking place. So, keeping an eye on avg_fragmentation_in_percent will ensure that your indexes are helping data access processes take place as efficiently as possible. Where fragmentation recurs frequently then potentially the DBA should consider; the fill_factor of the index in order to leave space at the leaf level so that new records can be inserted without causing fragmentation so rapidly. the columns used in the index should be analysed to avoid new records needing to be inserted in the middle of the index but rather always be added to the end. * – it’s approximate as there are many factors associated with things like the type of data and other database settings that affect this slightly.  Another great resource for working with SQL Server DMVs is Performance Tuning with SQL Server Dynamic Management Views by Louis Davidson and Tim Ford – a free ebook or paperback from Simple Talk. Disclaimer – Jonathan is a Friend of Red Gate and as such, whenever they are discussed, will have a generally positive disposition towards Red Gate tools. Other tools are often available and you should always try others before you come back and buy the Red Gate ones. All code in this blog is provided “as is” and no guarantee, warranty or accuracy is applicable or inferred, run the code on a test server and be sure to understand it before you run it on a server that means a lot to you or your manager.

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