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  • SQL SERVER Subquery or Join Various Options SQL Server Engine knows the Best

    This is followup post of my earlier article SQL SERVER Convert IN to EXISTS Performance Talk, after reading all the comments I have received I felt that I could write more on the same subject to clear few things out. First let us run following four queries, all of them are giving exactly [...]...Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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  • Nester

    - by csharp-source.net
    Nester is a tool for mutation testing of your C# source code in order to assess the adequacy of your unit tests. It involves modification of programs to see if existing tests can distinguish the original program from the modified program.

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  • An innovative approach to develop web forms - comparison with ASP.NET and MVC

    The article introduces an innovative approach to develop web forms in enterprise software rather than either ASP.NET or MVC through step by step comparison on development complexity, reusability, performance and maintainability. The approach is implemented as an important UI component of RapidWebDev...Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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  • Why is my laptop so sluggish? Or Damn You Facebook and Twitter! Or All Hail Chrome!

    - by John Conwell
    In the past three weeks, I've noticed that my laptop (dual core 2.1GHz, 2Gb RAM) has become amazingly sluggish.  I only uses for communications and data lookup workflows, so the slowness was tolerable.  But today I finally got fed up with the suckyness and decided to get to the root of the problem (I do have strong performance roots after all). It actually didn't take all that long to figure it out.  About a year ago I converted to Google Chrome (away from FireFox).  One of the great tools Chrome has is a "Task Manager" tool, that gives you Windows Task Manager like details for all the tabs open in the browser (Shift + Esc).  Since every tab runs in its own process, its easy from Task Manager (both Windows or Chrome) to identify and kill a single performance offending tab.  This is unlike IE, where you only get aggregate data about all tabs open.  Anyway, I digress.  Today my laptop sucked.  Windows Task Manager told me that I had two memory hogging Chrome tabs, but couldn't tell me which web page those tabs are showing.  Enter Chrome Task Manager which tells you the page title, along with CPU, memory and network utilization of each tab.  Enter my amazement.  Turns out Facebook was using just shy of half a Gb of RAM.  Half a Gigabyte!  That's 512 Megabytes!524,288 Kilobytes! 536,870,912 Bytes!  Or 4,294,967,296 Bits!  In other words, that's a frackin boat load of memory.  Now consider that Facebook is running on pretty much 96.3% (statistics based on absolutely nothing) of every house hold desktop, laptop, netbook, and mobile device in America, that is pretty horrific! And I wasn't playing any Facebook games like FarmWars or MafiaVille.  I just had my normal, default home page up showing me who just had breakfast, or just got finished with their morning run. I'm sorry...let me say that again...HALF A GIG OF RAM!  That is just unforgivable. I can just see my mom calling me up:  Mom: "John...I think I need a new computer.  Mine is really slow these days" John: "What do you have running?" Mom: "Oh, just Facebook" John: "Ok, close Facebook and tell me how fast your computer feels" Mom: "Well...I don't know how fast it is.  All I do is use Facebook" John: "Ok Mom, I'll send you a new computer by Tuesday" Oh yea...and the other offending web page?  It was Twitter, using a quarter of a Gigabyte. God I love social networks!

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  • Free eBooks - SQL Server and other Microsoft Technologies

    - by Greg Low
    Great to see the advice from Gail Erickson about the release of a number of SQL Server related eBooks on the new Microsoft eBook Gallery site. It's good to see this sort of content moving over to eBook formats.The e-books that are currently available include: SQL Server 2012 Transact-SQL DML Reference Master Data Services Capacity Guidelines Microsoft SQL Server AlwaysOn Solutions Guide for High Availability and Disaster Recovery QuickStart: Learn DAX Basics in 30 Minutes Microsoft SQL Server Analysis Services Multidimensional Performance and Operations Guide You'll find details of them here: http://social.technet.microsoft.com/wiki/contents/articles/11608.e-book-gallery-for-microsoft-technologies.aspx

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  • Getting Started with the New Column Store Index of SQL Server 2012

    Column Store Index, a new feature in SQL Server 2012, improves performance of data warehouse queries several folds. Arshad Ali shows you how to create column store index, and how to use index query hint to include or exclude a column store index. Schedule Azure backupsRed Gate’s Cloud Services makes it simple to create and schedule backups of your SQL Azure databases to Azure blob storage or Amazon S3. Try it for free today.

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  • test post, not public

    test test test more test more test more test more test This site is a resource for asp.net web programming. It has examples by Peter Kellner of techniques for high performance programming...Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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  • Google I/O 2010 - A JIT Compiler for Android's Dalvik VM

    Google I/O 2010 - A JIT Compiler for Android's Dalvik VM Google I/O 2010 - A JIT Compiler for Android's Dalvik VM Android 301 Ben Cheng, Bill Buzbee In this session we will outline the design of a JIT Compiler suitable for embedded Android devices. Topics will include an architectural overview, the rationale for design decisions and the special support for JIT verification, testing and tuning. For all I/O 2010 sessions, please go to code.google.com From: GoogleDevelopers Views: 3 0 ratings Time: 01:00:14 More in Science & Technology

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  • Should I install ubuntu on USB instead of HDD dual-boot?

    - by user2147243
    I had Ubuntu 12.04 installed as dual-boot OS on top of Vista on my laptop. Hacked the grub settings to default to Vista (instead of the default Ubuntu -- pain) on startup, and all was OK for occasional Ubuntu use for past 6 months. Then last week I got a strange message about 'lack of disk space' (~50MB free) when installing pxyplot, even though there was still about 6GB free disk space when I checked later. Then today the Ubuntu wouldn't load at all, and checking the HDD partitions in Vista it looked like the 15GB Ubuntu partition was now three smaller partitions! So, I got rid of those partitions and expanded the Vista partition to use the reclaimed space. Now can't restart ('grub rescue' appears and doesn't 'rescue' anything), so I'll have to do a boot recovery using a Vista installation CD. (Not a particularly user-friendly failure mode of the dual-boot installation!) I now have to decide to either a) try installing ubuntu on the HDD again, but don't want to stuff up my Vista ever again, as that is my most used OS, or b) install Ubuntu on a 16GB USB 3.0 stick. Apparently performance from USB won't be as good as from HDD, and running OS from USB stick does lots of r/w so the stick may fail after a few years! Perhaps installing Ubuntu on live USB and setup to then run in RAM would alleviate the performance/USB lifespan problems? If I create a live-USB for Ubuntu OS, will it boot off that when I restart the laptop with it plugged in? Or will I have to change the laptop setting for boot-order whenever I want to boot Ubuntu instead of Vista (that would be even more painful than the grub default boot order putting Ubuntu ahead of the existing Vista OS!) -- update: I recovered my Vista setup using Iolo SystemMechanic Disaster Recovery Tool, and created a bootable USB of Ubuntu 13.10 on an 8GB USB3.0 pendrive, with 4GB of 'persistence' to allow saving of settings, install some packages etc. It worked OK for a couple of test boots, but once I changed the time and desktop wallpaper, the next Ubuntu reboot crashed and I then couldn't get it to boot successfully. So I decided to install Ubuntu 12.04 LTS as a dual-boot again, but this time instead of partitioning the HDD and installing from an ISO DVD I used the wubi.exe tool to install Ubuntu as a dual-boot. Worked very well, although one oddity was that, despite asking how big the make the partition (20GB), the installed Ubuntu appears to be happily installed somewhere within the Vista NTFS file system (no partition shows up in Windows disk manager, and in Ubuntu disk management tool the entire 133 GB of HDD is showing, with ~40GB free space). A nice feature of installing the dual-boot using wubi is that the laptop now uses Windows boot manager on startup, with Vista as the default OS and Ubuntu happily listed as second on the list. So far so good.

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  • C-states and P-states : confounding factors for benchmarking

    - by Dave
    I was recently looking into a performance issue in the java.util.concurrent (JUC) fork-join pool framework related to particularly long latencies when trying to wake (unpark) threads in the pool. Eventually I tracked the issue down to the power & scaling governor and idle-state policies on x86. Briefly, P-states refer to the set of clock rates (speeds) at which a processor can run. C-states reflect the possible idle states. The deeper the C-state (higher numerical values) the less power the processor will draw, but the longer it takes the processor to respond and exit that sleep state on the next idle to non-idle transition. In some cases the latency can be worse than 100 microseconds. C0 is normal execution state, and P0 is "full speed" with higher Pn values reflecting reduced clock rates. C-states are P-states are orthogonal, although P-states only have meaning at C0. You could also think of the states as occupying a spectrum as follows : P0, P1, P2, Pn, C1, C2, ... Cn, where all the P-states are at C0. Our fork-join framework was calling unpark() to wake a thread from the pool, and that thread was being dispatched onto a processor at deep C-state, so we were observing rather impressive latencies between the time of the unpark and the time the thread actually resumed and was able to accept work. (I originally thought we were seeing situations where the wakee was preempting the waker, but that wasn't the case. I'll save that topic for a future blog entry). It's also worth pointing out that higher P-state values draw less power and there's usually some latency in ramping up the clock (P-states) in response to offered load. The issue of C-states and P-states isn't new and has been described at length elsewhere, but it may be new to Java programmers, adding a new confounding factor to benchmarking methodologies and procedures. To get stable results I'd recommend running at C0 and P0, particularly for server-side applications. As appropriate, disabling "turbo" mode may also be prudent. But it also makes sense to run with the system defaults to understand if your application exhibits any performance sensitivity to power management policies. The operating system power management sub-system typically control the P-state and C-states based on current and recent load. The scaling governor manages P-states. Operating systems often use adaptive policies that try to avoid deep C-states for some period if recent deep idle episodes proved to be very short and futile. This helps make the system more responsive under bursty or otherwise irregular load. But it also means the system is stateful and exhibits a memory effect, which can further complicate benchmarking. Forcing C0 + P0 should avoid this issue.

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  • What are the differences between Bigloo and ECL?

    - by Pubby
    I've been looking to embed Lisp in some C++ code. Two options I'm interested in is Bigloo Scheme and ECL. Reading through the docs they seem to support a very similar feature set. Obviously Bigloo is Scheme and ECL is CLisp, but what other differences do they have? In particular I'm interested in the following criteria: Ease of embedding (for C++, not just C) Performance Style of coding Size Tail call support I'm targeting this question towards someone who has used both.

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  • Byldan

    - by csharp-source.net
    Byldan is a framework for managing the build life-cycle of .NET applications. Its goal is to support multiple-platforms (Linux/Windows) and multiple compiler vendors (Novell/Microsoft). This minor release of Byldan adds support for unit testing with NUnit and for signing of assemblies.

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  • How to resolve concurrent ramp collisions in 2d platformer?

    - by Shaun Inman
    A bit about the physics engine: Bodies are all rectangles. Bodies are sorted at the beginning of every update loop based on the body-in-motion's horizontal and vertical velocity (to avoid sticky walls/floors). Solid bodies are resolved by testing the body-in-motion's new X with the old Y and adjusting if necessary before testing the new X with the new Y, again adjusting if necessary. Works great. Ramps (rectangles with a flag set indicating bottom-left, bottom-right, etc) are resolved by calculating the ratio of penetration along the x-axis and setting a new Y accordingly (with some checks to make sure the body-in-motion isn't attacking from the tall or flat side, in which case the ramp is treated as a normal rectangle). This also works great. Side-by-side ramps, eg. \/ and /\, work fine but things get jittery and unpredictable when a top-down ramp is directly above a bottom-up ramp, eg. < or > or when a bottom-up ramp runs right up to the ceiling/top-down ramp runs right down to the floor. I've been able to lock it down somewhat by detecting whether the body-in-motion hadFloor when also colliding with a top-down ramp or hadCeiling when also colliding with a bottom-up ramp then resolving by calculating the ratio of penetration along the y-axis and setting the new X accordingly (the opposite of the normal behavior). But as soon as the body-in-motion jumps the hasFloor flag becomes false, the first ramp resolution pushes the body into collision with the second ramp and collision resolution becomes jittery again for a few frames. I'm sure I'm making this more complicated than it needs to be. Can anyone recommend a good resource that outlines the best way to address this problem? (Please don't recommend I use something like Box2d or Chipmunk. Also, "redesign your levels" isn't an answer; the body-in-motion may at times be riding another body-in-motion, eg. a platform, that pushes it into a ramp so I'd like to be able to resolve this properly.) Thanks!

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  • How to troubleshoot a wireless networking regression?

    - by fluteflute
    I've been experiencing this perhaps slightly odd bug. It works flawlessly in Lucid, but not in Maverick and Natty. I find it seems to work when I'm booting a partition everyday (as I do for my main 10.10 partition) but for my 11.04 testing partition it's a real pain - usually refusing to connect. So given that I have both a working (10.04) and not-working (10.10 and 11.04) installs, how can I troubleshoot my problem?

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  • T-SQL User-Defined Functions: the good, the bad, and the ugly (part 2)

    - by Hugo Kornelis
    In a previous blog post , I demonstrated just how much you can hurt your performance by encapsulating expressions and computations in a user-defined function (UDF). I focused on scalar functions that didn’t include any data access. In this post, I will complete the discussion on scalar UDFs by covering the effect of data access in a scalar UDF. Note that, like the previous post, this all applies to T-SQL user-defined functions only. SQL Server also supports CLR user-defined functions (written in...(read more)

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  • Beware of Link Pedlars Bearing Gifts!

    As more organisations become aware of the value of links the number of links pedlars is increasing. On the face of it these people offer an easy, if sometimes expensive, way to improve your website's performance in the search engines.

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  • Découvrir la nouvelle génération CRM ? Connectez-vous au Customer Concepts TV le 24 april 2012

    - by Kinoa
    Accélérer votre stratégie commerciale  Les entreprises doivent repenser leurs processus de vente, optimiser leur performance, augmenter la productivité des équipes et se concentrer sur les opportunités à plus fort potentiel. Danny Rippon, Oracle CRM Solutions Sales Development Director, souhaite partager avec vous la stratégie gagnante dans cette video : la nouvelle génération de CRM. Vous y trouverez des conseils avisés pour tirer au maximum profit de votre CRM. Rejoignez-nous sur Customer Concepts TV ! Pour en savoir plus, visionnez cette video :

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  • Why is Double.Parse so slow?

    - by alexhildyard
    I was recently investigating a bottleneck in one of my applications, which read a CSV file from disk using a TextReader a line at a time, split the tokens, called Double.Parse on each one, then shunted the results into an object list. I was surprised to find it was actually the Double.Parse which seemed to be taking up most of the time.Googling turned up this, which is a little unfocused in places but throws out some excellent ideas:It makes more sense to work with binary format directly, rather than coerce strings into doublesThere is a significant performance improvement in composing doubles directly from the byte stream via long intermediariesString.Split is inefficient on fixed length recordsIn fact it turned out that my problem was more insidious and also more mundane -- a simple case of bad data in, bad data out. Since I had been serialising my Doubles as strings, when I inadvertently divided by zero and produced a "NaN", this of course was serialised as well without error. And because I was reading in using Double.Parse, these "NaN" fields were also (correctly) populating real Double objects without error. The issue is that Double.Parse("NaN") is incredibly slow. In fact, it is of the order of 2000x slower than parsing a valid double. For example, the code below gave me results of 357ms to parse 1000 NaNs, versus 15ms to parse 100,000 valid doubles.            const int invalid_iterations = 1000;            const int valid_iterations = invalid_iterations * 100;            const string invalid_string = "NaN";            const string valid_string = "3.14159265";            DateTime start = DateTime.Now;                        for (int i = 0; i < invalid_iterations; i++)            {                double invalid_double = Double.Parse(invalid_string);            }            Console.WriteLine(String.Format("{0} iterations of invalid double, time taken (ms): {1}",                invalid_iterations,                ((TimeSpan)DateTime.Now.Subtract(start)).Milliseconds            ));            start = DateTime.Now;            for (int i = 0; i < valid_iterations; i++)            {                double valid_double = Double.Parse(valid_string);            }            Console.WriteLine(String.Format("{0} iterations of valid double, time taken (ms): {1}",                valid_iterations,                ((TimeSpan)DateTime.Now.Subtract(start)).Milliseconds            )); I think the moral is to look at the context -- specifically the data -- as well as the code itself. Once I had corrected my data, the performance of Double.Parse was perfectly acceptable, and while clearly it could have been improved, it was now sufficient to my needs.

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  • ArchBeat Link-o-Rama for 2012-08-29

    - by Bob Rhubart
    ORCLville: OOW 2012 - Crystal BallOracle ACE Director Floyd Teter cooks up some tongue-in-cheek predictions for news and announcements that might come out of Oracle OpenWorld 2012. What's your prediction? Oracle Optimized Solutions at Oracle OpenWorld 2012 | Oracle Hardware Hardware matters, too! The people behind the Oracle Hardware blog have put together a list of Oracle Openworld 2012 sessions focused Oracle Optimized Solutions, "designed, pre-tested, tuned and fully documented architectures for optimal performance and availability." Just plug the session ID numbers into Schedule Builder and you're good to go. AIX Checklist for stable OBIEE deployment | Dick Dunbar "OBIEE is a complicated system with many moving parts and connection points," according to Oracle Business Inteligence escalation engineer Dick Dunbar. "The purpose of this article is to provide a checklist to discuss OBIEE deployment with your systems administrators." Demo for OPN: Coherence Management with EM Cloud Control 12c Oracle Partner Network members can check out a new Coherence Management demo that showcases some of the key capabilities of Management Pack for Oracle Coherence and JVM Diagnostics. "The demo flow showcases the key enhancements made in Enterprise Manager 12c release which includes new customizable performance summary, cache data management and configuration management," according to the WebLogic Partner Community EMEA blog. The Pragmatic Architect: To Boldly Go Where No One Has Gone Before | Frank Buschmann "Many architects have technical knowledge that's both impressive and sound, which is indeed an inevitable basis for design success," says Frank Buschmann. "Yet, a lot of software projects fail or suffer due to severe challenges in their architecture. The key to mastery is how architects approach design, what they value, and where they focus their attention and work." As retail dies, whom will be the winners? | Peter Evans-Greenwood "The problem for many retailers is that how consumers shop has changed but the the retailers haven't adapted, " says Peter Evans-Greenwood. "Their sole virtue was to be the last step in a supply chain delivering somebody else's products to the consumer. However, being the last step in the supply chain is no longer a virtue when consumers skip across channels and can reach around the globe, no longer dependant on or limited to what they can find locally." Thought for the Day "Brains require stimulation. If you're locked into a pattern of work, work, and more work, your brain soon habituates - the same way that it lets you stop hearing a clock ticking. So, if you want to be more effective at work, you must, paradoxically, be less single-minded in your devotion to work. Anything you do—anything—that stimulates new segments of your brain will make you a more effective programmer or analyst. I promise, with a money-back guarantee." — Gerald M. Weinberg Source: SoftwareQuotes.com

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  • 'Best Hypervisors' for VDI Tested by Citrix

    Citrix on Thursday described virtual desktop infrastructure performance differences using various hypervisors....Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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  • Starting this week: Dublin, Maidenhead, and London

    - by KKline
    This might be most most overcommitted four-week period of time ever in my life. I’m tired just thinking about it! Not only am I traveling internationally and speaking over the next few weeks, I’m also helping on two book projects, learning some new applications from Quest Software, and helping on a small Transact-SQL refactoring project. Swag on hand? I’ve got a special printing of 500 video training DVDs for this trip: SQL Server Training on DMVs Performance Monitor and Wait Events Plus, I’ll have...(read more)

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  • Oracle Advanced Compression Webcast Replay Available

    - by [email protected]
    Did you miss our webcast "Save BIG on Storage - with Oracle Database 11g and Advanced Compression"? Don't worry, you can still register and view the recording including the full Q&A session with Tim Shetler and Bill Hodak. Click here to learn how Oracle Advanced Compression can reduce your disk space requirements for all types of data, improve query and storage performance and lower storage costs throughout the datacenter.

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  • Are there any concerns with using a static read-only unit of work so that it behaves like a cache?

    - by Rowan Freeman
    Related question: How do I cache data that rarely changes? I'm making an ASP.NET MVC4 application. On every request the security details about the user will need to be checked with the area/controller/action that they are accessing to see if they are allowed to view it. The security information is stored in the database. For example: User Permission UserPermission Action ActionPermission A "Permission" is a token that is applied to an MVC action to indicate that the token is required in order to access the action. Once a user is given the permission (via the UserPermission table) then they have the token and can therefore access the action. I've been looking in to how to cache this data (since it rarely changes) so that I'm only querying in-memory data and not hitting a database (which is a considerable performance hit at the moment). I've tried storing things in lists, using a caching provider but I either run in to problems or performance doesn't improve. One problem that I constantly run in to is that I'm using lazy loading and dynamic proxies with EntityFramework. This means that even if I ToList() everything and store them somewhere static, the relationships are never populated. For example, User.Permissions is an ICollection but it's always null. I don't want to Include() everything because I'm trying to keep things simple and generic (and easy to modify). One thing I know is that an EntityFramework DbContext is a unit of work that acts with 1st-level caching. That is, for the duration of the unit of work, everything that is accessed is cached in memory. I want to create a read-only DbContext that will exist indefinitely and will only be used to read about permission data. Upon testing this it worked perfectly; my page load times went from 200ms+ to 20ms. I can easily force the data to refresh at certain intervals or simply leave it to refresh when the application pool is recycled. Basically it will behave like a cache. Note that the rest of the application will interact with other contexts that exist per request as normal. Is there any disadvantage to this approach? Could I be doing something different?

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