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  • How do I return an empty result set from a procedure using T-SQL?

    - by Kivin
    I'm interested in returning an empty result set from SQL Server stored procedures in certain events. The intended behaviour is that a L2SQL DataContext.SPName().SingleOrDefault() will result in CLR null value. I'm presently using the following solution, but I'm unsure whether it would be considered bad practice, a performance hazard (I could not find one by reading the execution plan), or if there is simply a better way: SELECT * FROM [dbo].[TableName] WHERE 0 = 1; The execution plan is a constant scan with a trivial cost associated with it. The reason I am asking this instead of simply not running any SELECTs is because I'm concerned previous SELECT @scalar or SELECT INTO statements could cause unintended result sets to be served back to L2SQL. Am I worrying over nothing?

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  • NoSql Crash Course/Tutorial

    - by Chris Thompson
    Hi all, I've seen NoSQL pop up quite a bit on SO and I have a solid understanding of why you would use it (from here, Wikipedia, etc). This could be due to the lack of concrete and uniform definition of what it is (more of a paradigm than concrete implementation), but I'm struggling to wrap my head around how I would go about designing a system that would use it or how I would implement it in my system. I'm really stuck in a relational-db mindset thinking of things in terms of tables and joins... At any rate, does anybody know of a crash course/tutorial on a system that would use it (kind of a "hello world" for a NoSQL-based system) or a tutorial that takes an existing "Hello World" app based on SQL and converts it to NoSQL (not necessarily in code, but just a high-level explanation). I see this having one solid answer, but if you guys feel like it should be community wiki, I'll be happy to change it. Thanks! Chris

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  • How to re-use a thread in Java ?

    - by David
    I am a building a console Sudoku Solver where the main objective is raw speed. I now have a ManagerThread that starts WorkerThreads to compute the neibhbors of each cell. So one WorkerThread is started for each cell right now. How can I re-use an existing thread that has completed its work? The Thread Pool Pattern seems to be the solution, but I don't understand what to do to prevent the thread from dying once its job has been completed. ps : I do not expect to gain much performance for this particular task, just want to experiment how multi-threading works before applying it to the more complex parts of the code. Thanks

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  • How Manage Big Linq DataContext ?

    - by Rev
    Hi The major problem in .net programs is "How manage memory for best performance". so Microsoft use garbage collector in .net and with that, we don't need to do something for managing memory(or better say we can use GC easily) But when you develop big project(business app), you make too many tables and database for your own project. so if you use Linq-to-sql, we must build DataContext include hundred or more tables. That make problem for program when you create an object from datacontext, that object give big amount of memory. also we cant divide datacontext to datacontexts(cuz relation between tables) so "How manage datacontext and memory"?

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  • Accomplishing boost::shared_from_this() in constructor via boost::shared_from_raw(this)

    - by Kyle
    Googling and poking around the boost code, it appears that it's now possible to construct a shared_ptr to this in a constructor, by inheriting from enable_shared_from_raw and calling shared_from_raw(this) Is there any documentation or examples of this? I'm finding nothing with google. Why am I not finding any useful buzz on this on google? I would have thought using shared_from_this in a constructor would be a hot/desirable item. Should I be inheriting from both enable_shared_from_raw and enable_shared_from_this, and restricting my usage of enable_shared_from_raw when I have to? If so, why? Is there a performance hit with shared_from_raw?

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  • Can games be considered real-time systems?

    - by harry
    I've been reading up on real-time systems and how they work etc. I was looking at the wikipedia article as well that said a game of Chess with a timer per move can be considered a real-time system because the program MUST compute a move in that time. What about other games? As we know, games generally try and run at 25+ FPS, could it be considered a soft real-time system since if it falls under 25 (I'm using 25 as a pre-defined threshold btw) it's not the end of the world, just a hit to the performance that we wanted? Also - games have events they must handle as well. The user uses the keyboard/mouse and the system must answer those events accordingly within (again) a pre-defined time, before the game is considered to have "failed". Oh, and I'm talking single-player for now to keep things simple. It sounds like games fit the soft real-time system criteria, but I'd like to know if I'm missing anything... thanks.

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  • spl_object_hash for PHP < 5.2 (unique ID for object instances)

    - by Rowan
    I'm trying to get unique IDs for object instances in PHP 5+. The function, spl_object_hash() is available from PHP 5.2 but I'm wondering if there's a workaround for older versions. There are a couple of functions in the comments on php.net but they're not working for me. The first (simplified): function spl_object_hash($object){ if (is_object($object)){ return md5((string)$object); } return null; } does not work with native objects (such as DOMDocument), and the second: function spl_object_hash($object){ if (is_object($object)){ ob_start(); var_dump($object); $dump = ob_get_contents(); ob_end_clean(); if (preg_match('/^object\(([a-z0-9_]+)\)\#(\d)+/i', $dump, $match)) { return md5($match[1] . $match[2]); } } return null; } looks like it could be a major performance buster! Does anybody have anything up their sleeve?

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  • Database indexes - what should they be

    - by WebweaverD
    Most of my database tables have a clear unique index through which lookups are done 90% of the time but I am a bit unsure on this one - I have a table which keeps track of user rating totals for items in my database, I now want to add another table, to track individual ratings with an ip address column to make sure no one can rate something twice. Since I can see this becoming a big, high use table it is important to optimize it correctly. (MYSQL table) This table will have the following fields: rating_id(always - unique), item_id (always - not unique), user_id (optional - not unique), ip_address (always - not unique), rating_value(always - not unique), has_review(bool) Now I envisions 90% the queries going something like this: When a user rates something - select where item_id = x and ip_address = y, (if rows = 0) insert rating When in user account pages - select where ip_address = x or username = y Now none of the fields searched on are unique, can I still use them as indexes (for example item _id and ip_address), can I have two indexes and will this still improve performance over a non indexed table?

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  • MicroChip Sample Code setting Current to a CMPDAC, DAC threshold which expect an voltage

    - by jason hong
    Sorry, the MicroChip Forum is very slow,I prefer to use overflow site to ask questions. dsPIC33FJ06GS101/X02 and dsPIC33FJ16GSX02/X04 device Sample Code // configure comparator2 CMPCON2bits.CMPON = 1; // enable comparator CMPCON2bits.INSEL = 1; // select CMP2B input pin (RB0) CMPCON2bits.RANGE = 1; // select high range, max DAC value = Avdd/2 //CMPDACx: COMPARATOR DAC CONTROL REGISTER //CMREF<9:0>: Comparator Reference Voltage Select bits CMPDAC2 = CURR_HWLIM; // DAC threshold #define CURR_HWLIM 1023 // 1023 // 10.15 * 101A MicroChip Sample code setting CURR_HWLIM which 1023A to COMPDAC2 which expects voltage I think that's mistake.

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  • Problem with Python 3.1(syntax error). Im a beginner please help!

    - by Jonathan
    Hi there, im new to pragraming :) I got a problem with sytax error while making a guessing game. the problem is in (if Gender = boy or Boy), the equal(=) letter is a syntax error. Please help! Answer = 23 Guess = () Gender = input("Are you a boy, a girl or an alien? ") if Gender = boy or Boy: print("Nice!", Gender) if Gender = girl or Girl: print("Prepare do die!", Gender) if Gender = alien or Alien: print("AWESOME my", Gender, "Friend!") While Guess != Answer: if Guess < Answer: print("Too low! try again") else: print("too high!" print("Congratulations you guessed correct!", Gender, "Have fun!" Thank

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  • Does a .NET 4.0 website load faster for a reason?

    - by Clarence Klopfstein
    I have been using DotNetBlogEngine for many years, and today my host (JodoHost.com) officially turned on support for .NET 4.0. What I've noticed immediately is that the website loads tremendously faster on the first load, subsequent loads are only slightly faster. The website is compiled as a .NET 2.0 web application. Is there a known reason for this performance increase? Was there a change in the .NET 4.0 framework that improved the initial load time of websites into an application pool? This is hosted on a 2003 server. Here is the site for reference: http://www.ocdprogrammer.com

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  • Java bytecode compiler benchmarks

    - by Dave Jarvis
    Q.1. What free compiler produces the fastest executable Java bytecode? Q.2. What free virtual machine executes Java bytecode the fastest (on 64-bit multi-core CPUs)? Q.3. What other (currently active) compiler projects are missing from this list: http://www.ibm.com/developerworks/java/jdk/ http://gcc.gnu.org/java/ http://openjdk.java.net/groups/compiler/ http://java.sun.com/javase/downloads/ http://download.eclipse.org/eclipse/downloads/ Q.4. What performance improvements can compilers do that JITs cannot (or do not)? Q.5. Where are some recent benchmarks, comparisons, or shoot-outs (for Q1 or Q2)? Thank you!

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  • Subversion for version control

    - by Gabriel Parenza
    Hi, I am working on an application whose primary purpose would be to provide source control management. My idea is to use to SVNKit for file check-out and check-in. However, while working with SVNKit, I realised it does not have the speed I was looking for. For instance, whenever developers create a ChangeRequest, which can encompass change in 3-40 files, I have to create a directory structure distributed across 32 folders. Doing so takes around 50 seconds, Another instance is that after creating change request developers can add files to the request. Copying even a single file from Trunk to branch takes around 6-7 secs. My question is has anyone had experience like this and what did you do to improve the performance? Moreover, is my approach correct? NOTE: I am using "http" protocol and can't use "svn" protocol.

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  • Is Win32_PerfFormattedData_PerfDisk_PhysicalDisk missing from WMI in Vista?

    - by Martin
    From what I understand, the following script should work in Windows XP and higher, but it doesn't work for me in Vista Business 32-bit Service Pack 2. Thus far I have been very unsuccessful googling for information about this performance class. strComputer = "." Set objWMIService = GetObject("winmgmts:\\" & strComputer & "\root\cimv2") Set colApps = objWMIService.ExecQuery("Select * from Win32_PerfFormattedData_PerfDisk_PhysicalDisk") For Each objApp in colApps Wscript.Echo objApp.Caption Next Does this WMI class simply not exist in Vista? If it is just me, is there a way to fix WMI? I have already tried running winmgmt /resetrepository and winmgmt /resyncperf and neither helps.

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  • How to estimate the thread context switching overhead?

    - by Ignas Limanauskas
    I am trying to improve the performance of the threaded application with real-time deadlines. It is running on Windows Mobile and written in C / C++. I have a suspicion that high frequency of thread switching might be causing tangible overhead, but can neither prove it or disprove it. As everybody knows, lack of proof is not a proof of opposite :). Thus my question is twofold: If exists at all, where can I find any actual measurements of the cost of switching thread context? Without spending time writing a test application, what are the ways to estimate the thread switching overhead in the existing application? Does anyone know a way to find out the number of context switches (on / off) for a given thread?

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  • What is design principle behind Servlets being Singleton

    - by Sandeep Jindal
    A servlet container "generally" create one instance of a servlet and different threads of the same instance to serve multiple requests. (I know this can be changed using deprecated SingleThreadModel and other features, but this is the usual way). I thought, the simple reason behind this is performance gain, as creating threads is better than creating instances. But it seems this is not the reason. On the other hand, creating instances have little advantage that developers never have to worry about thread safety. I am trying to understand the reason for this decision over the trade-off of thread-safety.

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  • Minimalistic PHP template engine with caching but not Smarty?

    - by Pekka
    There are loads of questions for "the right" PHP template engine, but none of them is focused on caching. Does anybody know a lightweight, high-quality, PHP 5 based template engine that does the following out of the box: Low-level templating functions (Replacements, loops, and filtering, maybe conditionals) Caching of the parsed results with the possibility to set an individual TTL per item, and of course to force a reload programmatically Extremely easy usage (like Smarty's) Modest in polluting the namespace (the ideal solution would be one class to interact with from the outside application) But not Smarty. I have nothing against, and often use, Smarty, but I am looking for something a bit simpler and leaner. I took a look at Fabien Potencier's Twig that looks very nice and compiles templates into PHP code, but it doesn't do any actual caching beyond that. I need and want a template engine, as I need to completely separate code and presentation in a way that a HTML designer can understand later on, so please no fundamental discussions about whether template engines in PHP make sense. Those discussions are important, but they already exist on SO.

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  • I don't understand Application Domains

    - by Jeremy Edwards
    .NET has this concept of Application Domains which from what I understand can be used to load an assembly into memory. I've done some research on Application Domains as well as go to my local book store for some additional knowledge on this subject matter but it seems very scarce. All I know that I can do with Application Domains is to load assemblies in memory and I can unload them when I want. What are the capabilities other that I have mentioned of Application Domains? Do Threads respect Application Domains boundaries? Are there any drawbacks from loading Assemblies in different Application Domains other than the main Application Domains beyond performance of communication? Links to resources that discuss Application Domains would be nice as well. I've already checked out MSDN which doesn't have that much information about them.

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  • MySQL - are FK's useful / viable in a web app?

    - by yoda
    Hi all, I've encountered this discussion related to FK's and web applications. Basically some people say that FK's in web applications doesn't represent a real improvement and can even make the application slower in some cases. What do you guys think, what's your experience? -- A quote from Heikki Tuuri, creator of InnoDB engine, founder and CEO of Innobase: InnoDB checks foreign keys as soon as a row is updated, no batching is performed or checks delayed till transaction commit Foreign keys are often serious performance overhead, but help maintain data consistency Foreign Keys increase amount of row level locking done and can make it spread to a lot of tables besides the ones directly updated

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  • MS Sql Full-text search vs. LIKE expression

    - by Marks
    Hi. I'm currently looking for a way to search a big database (500MB - 10GB or more on 10 tables) with a lot of different fields(nvarchars and bigints). Many of the fields, that should be searched are not in the same table. An example: A search for '5124 Peter' should return all items, that ... have an ID with 5124 in it, have 'Peter' in the title or description have item type id with 5124 in it created by a user named 'peter' or a user whose id has 5124 in it created by a user with '5124' or 'peter' in his street address. How should i do the search? I read that the full-text search of MS-Sql is a lot more performant than a query with the LIKE keyword and i think the syntax is more clear, but i think it cant search on bigint(id) values and i read it has performance problems with indexing and therefore slows down inserts to the DB. In my project there will be more inserting than reading, so this could be a matter. Thanks in advance, Marks

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  • What is the best way for communication between cluster nodes

    - by Tom
    I have an application written in a combination of ASP/VB6/VBScript and ASP.NET/C# that consists of a website part, SOAP-like webservice part and a queue processing part processing incoming files in a hotfolder. We are used to running under load balancers (Microsoft or other make). Often we need to communicate between the different load balanced servers. Currently we do this through the SQL Server database that is common for all nodes, however, this comes with a performance penalty as each message requires a transaction and continual polling from the other nodes. What would be better ways to achieve this? Tom, Appelby

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  • Multiple Broadcast Messages with Less Data or Less Broadcast Messages with More Data?

    - by niko
    Hi, I am developing an application which is communicating with the server. Tha application can perform log-in and get different parameters from server. The application consists of a RESTful client (custom class for making requests), Communication Service (the service which runs in the background) and the main activity. For now I created multiple broadcast messages and multiple broadcast receivers in the main activity so when the application performs login operation a receiver (loginBroadcastReceiver) in the main activity receives a message and when another parameter is received from the server different message is broadcasted and another receiver handles the message. This way however the application performance is poor but I am not sure whether it is due to multiple broadcast receivers. Does anyone know what is the best way to exchange data between service and main activity - is it better to create a single broadcast receiver and retrieve all parameters from message or is it better to initialize multiple broadcast receivers for multiple parameters? I would appreciate if you could provide any useful resource about the topic because I'm writing the thesis and it would be good if the solution could be explained.

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  • What are the pros and cons to keeping SQL in Stored Procs versus Code

    - by Guy
    What are the advantages/disadvantages of keeping SQL in your C# source code or in Stored Procs? I've been discussing this with a friend on an open source project that we're working on (C# ASP.NET Forum). At the moment, most of the database access is done by building the SQL inline in C# and calling to the SQL Server DB. So I'm trying to establish which, for this particular project, would be best. So far I have: Advantages for in Code: Easier to maintain - don't need to run a SQL script to update queries Easier to port to another DB - no procs to port Advantages for Stored Procs: Performance Security

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  • How to find good looking font color if background color is known?

    - by Mecki
    There seem to be so many color wheel, color picker, and color matcher web apps out there, where you give one color and the they'll find a couple of other colors that will create a harmonic layout when being used in combination. However most of them focus on background colors only and any text printed on each background color (if text is printed at all in the preview) is either black or white. My problem is different. I know the background color I want to use for a text area. What I need help with is choosing a couple of colors (the more, the merrier) I can use as font colors on this background. Most important is that the color will make sure the font is readable (contrast not being too low, also maybe not being too high to avoid that eyes are stressed) and of course that the combination of foreground and background just looks good. Anyone being aware of such an application? I'd prefer a web application to anything I have to download. Thanks.

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  • Which web Tier Framework for a public commercial website with heavy load ?

    - by Maxime ARNSTAMM
    Hello everyone, As a part of an enterprise architecture exercise, i need to find a java-based framework filling these constraints : heavy (i think) load : 5000 concurrent connections widely known : can't be too exotic, the contractors would be too high priced. relatively easy to use : developpement time must be reasonnable must be as compliant as possible with the css/html layout produced by a designer Must look like "web 2.0" from the marketing point of view. What i learned from my limited experience is : jsf : 1, don't know. 2, 3 ok. 4 not ok (at least not without huge effort) wicket : 1, not really. 2, 3 and 4 ok. gwt : 1, don't know. 2, 3 ok. 4 not ok (but more ok than jsf) others : not really "web 2.0" or not really known I'm really junior, so my ideas about those frameworks are probably wrong, that's why i come to you, stackoverflowees. Thanks for helping :)

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