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• How to Handle frame rates and synchronizing screen repaints

  - by David Kroukamp

  I would first off say sorry if the title is worded incorrectly. Okay now let me give the scenario I'm creating a 2 player fighting game, An average battle will include a Map (moving/still) and 2 characters (which are rendered by redrawing a varying amount of sprites one after the other). Now at the moment I have a single game loop limiting me to a set number of frames per second (using Java): Timer timer = new Timer(0, new AbstractAction() { @Override public void actionPerformed(ActionEvent e) { long beginTime; //The time when the cycle begun long timeDiff; //The time it took for the cycle to execute int sleepTime; //ms to sleep (< 0 if we're behind) int fps = 1000 / 40; beginTime = System.nanoTime() / 1000000; //execute loop to update check collisions and draw gameLoop(); //Calculate how long did the cycle take timeDiff = System.nanoTime() / 1000000 - beginTime; //Calculate sleep time sleepTime = fps - (int) (timeDiff); if (sleepTime > 0) {//If sleepTime > 0 we're OK ((Timer)e.getSource()).setDelay(sleepTime); } } }); timer.start(); in gameLoop() characters are drawn to the screen ( a character holds an array of images which consists of their current sprites) every gameLoop() call will change the characters current sprite to the next and loop if the end is reached. But as you can imagine if a sprite is only 3 images in length than calling gameLoop() 40 times will cause the characters movement to be drawn 40/3=13 times. This causes a few minor anomilies in the sprited for some charcters So my question is how would I go about delivering a set amount of frames per second in when I have 2 characters on screen with varying amount of sprites?

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• What is the best practice for when to check if something needs to be done?

  - by changokun

  Let's say I have a function that does x. I pass it a variable, and if the variable is not null, it does some action. And I have an array of variables and I'm going to run this function on each one. Inside the function, it seems like a good practice is to check if the argument is null before proceeding. A null argument is not an error, it just causes an early return. I could loop through the array and pass each value to the function, and the function will work great. Is there any value to checking if the var is null and only calling the function if it is not null during the loop? This doubles up on the checking for null, but: Is there any gained value? Is there any gain on not calling a function? Any readability gain on the loop in the parent code? For the sake of my question, let's assume that checking for null will always be the case. I can see how checking for some object property might change over time, which makes the first check a bad idea. Pseudo code example: for(thing in array) { x(thing) } Versus: for(thing in array) { if(thing not null) x(thing) } If there are language-specific concerns, I'm a web developer working in PHP and JavaScript.

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• Any Practical Alternative to the Signals + Slots model for GUI Programming?

  - by IntermediateHacker

  The majority of GUI Toolkits nowadays use the Signals + Slots model. It was Qt and GTK+, if I am not wrong, who pioneered it. You know, the widgets or graphical objects (sometimes even ones that aren't displayed) send signals to the main-loop handler. The main-loop handler then calls the events, callbacks or slots assigned for that widget / graphical object. There are usually default (and in most cases virtual) event-handlers already provided by the toolkit for handling all pre-defined signals, therefore, unlike previous designs where the developer had to write the entire main-loop and handler for each and every message himself (think WINAPI), the developer only has to worry about the signals he needs to implement new functionality on. Now this design is being used in most modern toolkits as far as I know. There are Qt, GTK+, FLTK etc. There is Java Swing. C# even has a language feature for it ( events and delegates ), and Windows Forms has been developed on this design. In fact, over the last decade, this design for GUI programming has become a kind of an unwritten standard. Since it increases productivity and provides greater abstraction. However, my question is: Is there any alternative design, that is parallel or practical for modern GUI programming? i.e Is the Signals + Slots design, the only practical one in town? Is it feasible to do GUI Programming with any other design? Are any modern (preferably successful and popular) GUI toolkits built on an alternative design?

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• Implementing the transport layer for a SIP UAC

  - by Jonathan Henson

  I have a somewhat simple, but specific, question about implementing the transport layer for a SIP UAC. Do I expect the response to a request on the same socket that I sent the request on, or do I let the UDP or TCP listener pick up the response and then route it to the correct transaction from there? The RFC does not seem to say anything on the matter. It seems that especially using UDP, which is connection-less, that I should just let the listeners pick up the response, but that seems sort of counter intuitive. Particularly, I have seen plenty of UAC implementations which do not depend on having a Listener in the transport layer. Also, most implementations I have looked at do not have the UAS receiving loop responding on the socket at all. This would tend to indicate that the client should not be expecting a reply on the socket that it sent the request on. For clarification: Suppose my transport layer consists of the following elements: TCPClient (Sends Requests for a UAC via TCP) UDPClient (Sends Requests for a UAC vid UDP) TCPSever (Loop receiving Requests and dispatching to transaction layer via TCP) UDPServer (Loop receiving Requests and dispatching to transaction layer via UDP) Obviously, the *Client sends my Requests. The question is, what receives the Response? The *Client waiting on a recv or recvfrom call on the socket it used to send the request, or the *Server? Conversely, the *Server receives my requests, What sends the Response? The *Client? doesn't this break the roles of each member a bit?

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• How to parse JSON data from web more faster [closed]

  - by Kaidul Islam Sazal

  I have json inventory inventory.json on the server like this: [ { "body" : "SUV", "color" : { "ext" : "White diamond pearl", "int" : "Taupe" }, "id" : "276181", "make" : "Acura", "miles" : 35949, "model" : "RDX", "pic" : [ { "full" : "http://images1.dealercp.com/90961/000JNBD/001_0292.jpg" } ], "power" : { "drive" : "Front wheel drive", "eng" : "2.3L DOHC PGM-FI 16-VALVE", "trans" : "Automatic" }, "price" : { "net" : 29488 }, "stock" : "6942", "trim" : "AWD 4dr Tech Pkg SUV", "vin" : "5J8TB2H53BA000334", "year" : 2011 }, { "body" : "Sedan", "color" : { "ext" : "Premium white pearl", "int" : "Taupe" }, "id" : "275622", "make" : "Acura", "miles" : 40923, "model" : "TSX", "pic" : [ { "full" : "http://images1.dealercp.com/90961/000JMC6/001_1765.jpg" } ], "power" : { "drive" : "Front wheel drive", "eng" : "2.4L L4 MPI DOHC 16V", "trans" : "Automatic" }, "price" : { "net" : 22288 }, "stock" : "6945", "trim" : "4dr Sdn I4 Auto Sedan", "vin" : "JH4CU2F66AC011933", "year" : 2010 } ] here are two index, There are almost 5000 index like this. I parsed this json like this: var url = "inventory/inventory.json"; $.getJSON(url, function(data){ $.each(data, function(index, item){ //straight-forward loop if(item.year == 2012) { $('#desc').append(item.make + ' ' + item.model + ' ' + '<br/>' + item.price.net + '<br/>' + item.pic[0].full); } }); }); This is working fine.But the problem is that, this searching and fetching process is little bit slow as there are 5000 indexes already and it's increasing day by day. It seems that, it is a straight-forward loop to parse the data and a normal brute-force method. Now I want to know if there any time efiicient way to parse more faster.Any faster method to parse instead of straight-forward loop ?

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• How to tell your boss that he's a bad programmer? [closed]

  - by Doe

  Possible Duplicate: How to tell your boss that his programming style is really bad? There was a question about the boss having a bad programming style (weird booleans, empty loops, etc.) Having a bad/weird style does not imply being a bad programmer, but my situation is different. My boss outputs some really nasty code for the project, on which we are working together (just two of us). Examples: functions that span over several screens (big screens - 1900 x 1200) Deeply nested Conditional and Loop statements (up to 10 levels!!) Too much static variables, singletons, and both (singleton class with all the methods and members also static) Sometimes the code committed to the version control system does not even compile! Copy-Paste code instead of separating it into an independent function. Fail all the deadlines. "This's [C#|Java|Python] it shouldn't be efficient, that's why we loop all over the haystack to find the needle." "This's C/C++, it's fast enough to loop all over the haystack to find the needle." There is much more to mention... But the worst is that I have to redo much of the stuff he does, my code, which I try to keep clean is often polluted with above-mentioned atrocities. He's reaching 30 soon, so all his skills are established, and I don't even know if it's possible to change something. I like the project, but sometimes I just want to quit...

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• Gnome Do not Launching

  - by PyRulez

  When I try running gnome do, I get this. chris@Chris-Ubuntu-Laptop:~$ gnome-do pgrep: invalid user name: -u and it is not writable Trying sudo: chris@Chris-Ubuntu-Laptop:~$ sudo gnome-do [NetworkService] Could not initialize Network Manager dbus: Unable to open the session message bus. [Error 17:54:30.122] [SystemService] Could not initialize dbus: Unable to open the session message bus. (Do:2401): Wnck-CRITICAL **: wnck_set_client_type got called multiple times. (Do:2401): libdo-WARNING **: Binding '<Super>space' failed! [Error 17:54:30.649] [AbstractKeyBindingService] Key "" is already mapped. Tomboy.NotesItemSource "Tomboy Notes" encountered an error in UpdateItems: System.TypeInitializationException: An exception was thrown by the type initializer for Tomboy.TomboyDBus ---> System.Exception: Unable to open the session message bus. ---> System.ArgumentNullException: Argument cannot be null. Parameter name: address at NDesk.DBus.Bus.Open (System.String address) [0x00000] in <filename unknown>:0 at NDesk.DBus.Bus.get_Session () [0x00000] in <filename unknown>:0 --- End of inner exception stack trace --- at NDesk.DBus.Bus.get_Session () [0x00000] in <filename unknown>:0 at Tomboy.TomboyDBus..cctor () [0x00000] in <filename unknown>:0 --- End of inner exception stack trace --- at Tomboy.NotesItemSource.UpdateItems () [0x00000] in <filename unknown>:0 at Do.Universe.Safe.SafeItemSource.UpdateItems () [0x00000] in <filename unknown>:0 . Firefox.PlacesItemSource "Firefox Places" encountered an error in UpdateItems: System.InvalidCastException: Cannot cast from source type to destination type. at Mono.Data.Sqlite.SqliteDataReader.VerifyType (Int32 i, DbType typ) [0x00000] in <filename unknown>:0 at Mono.Data.Sqlite.SqliteDataReader.GetString (Int32 i) [0x00000] in <filename unknown>:0 at Firefox.PlacesItemSource+<LoadPlaceItems>c__Iterator3.MoveNext () [0x00000] in <filename unknown>:0 at System.Collections.Generic.List`1[Firefox.PlaceItem].AddEnumerable (IEnumerable`1 enumerable) [0x00000] in <filename unknown>:0 at System.Collections.Generic.List`1[Firefox.PlaceItem]..ctor (IEnumerable`1 collection) [0x00000] in <filename unknown>:0 at System.Linq.Enumerable.ToArray[PlaceItem] (IEnumerable`1 source) [0x00000] in <filename unknown>:0 at Firefox.PlacesItemSource.UpdateItems () [0x00000] in <filename unknown>:0 at Do.Universe.Safe.SafeItemSource.UpdateItems () [0x00000] in <filename unknown>:0 . Do.Universe.Linux.GNOMESpecialLocationsItemSource "GNOME Special Locations" encountered an error in UpdateItems: System.IO.FileNotFoundException: Could not find file "/root/.gtk-bookmarks". File name: '/root/.gtk-bookmarks' at System.IO.FileStream..ctor (System.String path, FileMode mode, FileAccess access, FileShare share, Int32 bufferSize, Boolean anonymous, FileOptions options) [0x00000] in <filename unknown>:0 at System.IO.FileStream..ctor (System.String path, FileMode mode, FileAccess access, FileShare share) [0x00000] in <filename unknown>:0 at (wrapper remoting-invoke-with-check) System.IO.FileStream:.ctor (string,System.IO.FileMode,System.IO.FileAccess,System.IO.FileShare) at System.IO.File.OpenRead (System.String path) [0x00000] in <filename unknown>:0 at System.IO.StreamReader..ctor (System.String path, System.Text.Encoding encoding, Boolean detectEncodingFromByteOrderMarks, Int32 bufferSize) [0x00000] in <filename unknown>:0 at System.IO.StreamReader..ctor (System.String path) [0x00000] in <filename unknown>:0 at (wrapper remoting-invoke-with-check) System.IO.StreamReader:.ctor (string) at Do.Universe.Linux.GNOMESpecialLocationsItemSource+<ReadBookmarkItems>c__Iterator3.MoveNext () [0x00000] in <filename unknown>:0 at Do.Universe.Linux.GNOMESpecialLocationsItemSource.UpdateItems () [0x00000] in <filename unknown>:0 at Do.Universe.Safe.SafeItemSource.UpdateItems () [0x00000] in <filename unknown>:0 . ^[^\Full thread dump: "<unnamed thread>" tid=0x0xb7570700 this=0x0x56f18 thread handle 0x403 state : not waiting owns () at (wrapper managed-to-native) Mono.Unix.Native.Syscall.read (int,intptr,ulong) <0xffffffff> at Mono.Unix.Native.Syscall.read (int,void*,ulong) <0x00023> at Mono.Unix.UnixStream.Read (byte[],int,int) <0x0008b> at NDesk.DBus.Connection.ReadMessage () <0x0003c> at NDesk.DBus.Connection.Iterate () <0x0001b> at NDesk.DBus.BusG/<Init>c__AnonStorey0.<>m__0 (intptr,NDesk.GLib.IOCondition,intptr) <0x00033> at (wrapper native-to-managed) NDesk.DBus.BusG/<Init>c__AnonStorey0.<>m__0 (intptr,NDesk.GLib.IOCondition,intptr) <0xffffffff> at (wrapper managed-to-native) Gtk.Clipboard.gtk_clipboard_wait_is_text_available (intptr) <0xffffffff> at Gtk.Clipboard.WaitIsTextAvailable () <0x00017> at Do.Universe.SelectedTextItem.UpdateSelection (object,System.EventArgs) <0x00027> at Do.Platform.AbstractApplicationService.OnSummoned () <0x00025> at Do.Platform.ApplicationService.<ApplicationService>m__31 (object,System.EventArgs) <0x00013> at Do.Core.Controller.OnSummoned () <0x00025> at Do.Core.Controller.Summon () <0x00027> at Do.Do.Main (string[]) <0x001eb> at (wrapper runtime-invoke) <Module>.runtime_invoke_void_object (object,intptr,intptr,intptr) <0xffffffff> "<unnamed thread>" tid=0x0xb2c81b40 this=0x0x194150 thread handle 0x412 state : interrupted state owns () at (wrapper managed-to-native) System.IO.InotifyWatcher.ReadFromFD (intptr,byte[],intptr) <0xffffffff> at System.IO.InotifyWatcher.Monitor () <0x0005f> at System.Threading.Thread.StartInternal () <0x00057> at (wrapper runtime-invoke) object.runtime_invoke_void__this__ (object,intptr,intptr,intptr) <0xffffffff> "Universe Update Dispatcher" tid=0x0xb29ffb40 this=0x0x569d8 thread handle 0x41b state : interrupted state owns () at (wrapper managed-to-native) System.Threading.WaitHandle.WaitOne_internal (System.Threading.WaitHandle,intptr,int,bool) <0xffffffff> at System.Threading.WaitHandle.WaitOne (System.TimeSpan,bool) <0x00133> at System.Threading.WaitHandle.WaitOne (System.TimeSpan) <0x00022> at Do.Core.UniverseManager.UniverseUpdateLoop () <0x0007a> at System.Threading.Thread.StartInternal () <0x00057> at (wrapper runtime-invoke) object.runtime_invoke_void__this__ (object,intptr,intptr,intptr) <0xffffffff> Tomboy.NotesItemSource "Tomboy Notes" encountered an error in UpdateItems: System.TypeInitializationException: An exception was thrown by the type initializer for Tomboy.TomboyDBus ---> System.Exception: Unable to open the session message bus. ---> System.ArgumentNullException: Argument cannot be null. Parameter name: address at NDesk.DBus.Bus.Open (System.String address) [0x00000] in <filename unknown>:0 at NDesk.DBus.Bus.get_Session () [0x00000] in <filename unknown>:0 --- End of inner exception stack trace --- at NDesk.DBus.Bus.get_Session () [0x00000] in <filename unknown>:0 at Tomboy.TomboyDBus..cctor () [0x00000] in <filename unknown>:0 --- End of inner exception stack trace --- at Tomboy.NotesItemSource.UpdateItems () [0x00000] in <filename unknown>:0 at Do.Universe.Safe.SafeItemSource.UpdateItems () [0x00000] in <filename unknown>:0 . Firefox.PlacesItemSource "Firefox Places" encountered an error in UpdateItems: System.InvalidCastException: Cannot cast from source type to destination type. at Mono.Data.Sqlite.SqliteDataReader.VerifyType (Int32 i, DbType typ) [0x00000] in <filename unknown>:0 at Mono.Data.Sqlite.SqliteDataReader.GetString (Int32 i) [0x00000] in <filename unknown>:0 at Firefox.PlacesItemSource+<LoadPlaceItems>c__Iterator3.MoveNext () [0x00000] in <filename unknown>:0 at System.Collections.Generic.List`1[Firefox.PlaceItem].AddEnumerable (IEnumerable`1 enumerable) [0x00000] in <filename unknown>:0 at System.Collections.Generic.List`1[Firefox.PlaceItem]..ctor (IEnumerable`1 collection) [0x00000] in <filename unknown>:0 at System.Linq.Enumerable.ToArray[PlaceItem] (IEnumerable`1 source) [0x00000] in <filename unknown>:0 at Firefox.PlacesItemSource.UpdateItems () [0x00000] in <filename unknown>:0 at Do.Universe.Safe.SafeItemSource.UpdateItems () [0x00000] in <filename unknown>:0 . Do.Universe.Linux.GNOMESpecialLocationsItemSource "GNOME Special Locations" encountered an error in UpdateItems: System.IO.FileNotFoundException: Could not find file "/root/.gtk-bookmarks". File name: '/root/.gtk-bookmarks' at System.IO.FileStream..ctor (System.String path, FileMode mode, FileAccess access, FileShare share, Int32 bufferSize, Boolean anonymous, FileOptions options) [0x00000] in <filename unknown>:0 at System.IO.FileStream..ctor (System.String path, FileMode mode, FileAccess access, FileShare share) [0x00000] in <filename unknown>:0 at (wrapper remoting-invoke-with-check) System.IO.FileStream:.ctor (string,System.IO.FileMode,System.IO.FileAccess,System.IO.FileShare) at System.IO.File.OpenRead (System.String path) [0x00000] in <filename unknown>:0 at System.IO.StreamReader..ctor (System.String path, System.Text.Encoding encoding, Boolean detectEncodingFromByteOrderMarks, Int32 bufferSize) [0x00000] in <filename unknown>:0 at System.IO.StreamReader..ctor (System.String path) [0x00000] in <filename unknown>:0 at (wrapper remoting-invoke-with-check) System.IO.StreamReader:.ctor (string) at Do.Universe.Linux.GNOMESpecialLocationsItemSource+<ReadBookmarkItems>c__Iterator3.MoveNext () [0x00000] in <filename unknown>:0 at Do.Universe.Linux.GNOMESpecialLocationsItemSource.UpdateItems () [0x00000] in <filename unknown>:0 at Do.Universe.Safe.SafeItemSource.UpdateItems () [0x00000] in <filename unknown>:0 . It stops when I try my key combination, ctrl-alt-. It does not pop up though.

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• SQL SERVER – Weekly Series – Memory Lane – #052

  - by Pinal Dave

  Let us continue with the final episode of the Memory Lane Series. Here is the list of selected articles of SQLAuthority.com across all these years. Instead of just listing all the articles I have selected a few of my most favorite articles and have listed them here with additional notes below it. Let me know which one of the following is your favorite article from memory lane. 2007 Set Server Level FILLFACTOR Using T-SQL Script Specifies a percentage that indicates how full the Database Engine should make the leaf level of each index page during index creation or alteration. fillfactor must be an integer value from 1 to 100. The default is 0. Limitation of Online Index Rebuld Operation Online operation means when online operations are happening in the database are in normal operational condition, the processes which are participating in online operations does not require exclusive access to the database. Get Permissions of My Username / Userlogin on Server / Database A few days ago, I was invited to one of the largest database company. I was asked to review database schema and propose changes to it. There was special username or user logic was created for me, so I can review their database. I was very much interested to know what kind of permissions I was assigned per server level and database level. I did not feel like asking Sr. DBA the question about permissions. Simple Example of WHILE Loop With CONTINUE and BREAK Keywords This question is one of those questions which is very simple and most of the users get it correct, however few users find it confusing for the first time. I have tried to explain the usage of simple WHILE loop in the first example. BREAK keyword will exit the stop the while loop and control is moved to the next statement after the while loop. CONTINUE keyword skips all the statement after its execution and control is sent to the first statement of while loop. Forced Parameterization and Simple Parameterization – T-SQL and SSMS When the PARAMETERIZATION option is set to FORCED, any literal value that appears in a SELECT, INSERT, UPDATE or DELETE statement is converted to a parameter during query compilation. When the PARAMETERIZATION database option is SET to SIMPLE, the SQL Server query optimizer may choose to parameterize the queries. 2008 Transaction and Local Variables – Swap Variables – Update All At Once Concept Summary : Transaction have no effect over memory variables. When UPDATE statement is applied over any table (physical or memory) all the updates are applied at one time together when the statement is committed. First of all I suggest that you read the article listed above about the effect of transaction on local variant. As seen there local variables are independent of any transaction effect. Simulate INNER JOIN using LEFT JOIN statement – Performance Analysis Just a day ago, while I was working with JOINs I find one interesting observation, which has prompted me to create following example. Before we continue further let me make very clear that INNER JOIN should be used where it cannot be used and simulating INNER JOIN using any other JOINs will degrade the performance. If there are scopes to convert any OUTER JOIN to INNER JOIN it should be done with priority. 2009 Introduction to Business Intelligence – Important Terms & Definitions Business intelligence (BI) is a broad category of application programs and technologies for gathering, storing, analyzing, and providing access to data from various data sources, thus providing enterprise users with reliable and timely information and analysis for improved decision making. Difference Between Candidate Keys and Primary Key Candidate Key – A Candidate Key can be any column or a combination of columns that can qualify as unique key in database. There can be multiple Candidate Keys in one table. Each Candidate Key can qualify as Primary Key. Primary Key – A Primary Key is a column or a combination of columns that uniquely identify a record. Only one Candidate Key can be Primary Key. 2010 Taking Multiple Backup of Database in Single Command – Mirrored Database Backup I recently had a very interesting experience. In one of my recent consultancy works, I was told by our client that they are going to take the backup of the database and will also a copy of it at the same time. I expressed that it was surely possible if they were going to use a mirror command. In addition, they told me that whenever they take two copies of the database, the size of the database, is always reduced. Now this was something not clear to me, I said it was not possible and so I asked them to show me the script. Corrupted Backup File and Unsuccessful Restore The CTO, who was also present at the location, got very upset with this situation. He then asked when the last successful restore test was done. As expected, the answer was NEVER.There were no successful restore tests done before. During that time, I was present and I could clearly see the stress, confusion, carelessness and anger around me. I did not appreciate the feeling and I was pretty sure that no one in there wanted the atmosphere like me. 2011 TRACEWRITE – Wait Type – Wait Related to Buffer and Resolution SQL Trace is a SQL Server database engine technology which monitors specific events generated when various actions occur in the database engine. When any event is fired it goes through various stages as well various routes. One of the routes is Trace I/O Provider, which sends data to its final destination either as a file or rowset. DATEDIFF – Accuracy of Various Dateparts If you want to have accuracy in seconds, you need to use a different approach. In the first example, the accurate method is to find the number of seconds first and then divide it by 60 to convert it in minutes. Dedicated Access Control for SQL Server Express Edition http://www.youtube.com/watch?v=1k00z82u4OI Book Signing at SQLPASS 2012 Who I Am And How I Got Here – True Story as Blog Post If there was a shortcut to success – I want to know. I learnt SQL Server hard way and I am still learning. There are so many things, I have to learn. There is not enough time to learn everything which we want to learn. I am constantly working on it every day. I welcome you to join my journey as well. Please join me in my journey to learn SQL Server – more the merrier. Vacation, Travel and Study – A New Concept Even those who have advanced degrees and went to college for years, or even decades, find studying hard.  There is a difference between studying for a career and studying for a certification.  At least to get a degree there is a variety of subjects, with labs, exams, and practice problems to make things more interesting. Order By Numeric Values Formatted as String We have a table which has a column containing alphanumeric data. The data always has first as an integer and later part as a string. The business need is to order the data based on the first part of the alphanumeric data which is an integer. Now the problem is that no matter how we use ORDER BY the result is not produced as expected. Let us understand this with an example. Resolving SQL Server Connection Errors – SQL in Sixty Seconds #030 – Video One of the most famous errors related to SQL Server is about connecting to SQL Server itself. Here is how it goes, most of the time developers have worked with SQL Server and knows pretty much every error which they face during development language. However, hardly they install fresh SQL Server. As the installation of the SQL Server is a rare occasion unless you are a DBA who is responsible for such an instance – the error faced during installations are pretty rare as well. http://www.youtube.com/watch?v=1k00z82u4OI Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: Memory Lane, PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology

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• C++ - Conway's Game of Life & Stepping Backwards

  - by Gabe

  I was able to create a version Conway's Game of Life that either stepped forward each click, or just ran forward using a timer. (I'm doing this using Qt.) Now, I need to be able to save all previous game grids, so that I can step backwards by clicking a button. I'm trying to use a stack, and it seems like I'm pushing the old gridcells onto the stack correctly. But when I run it in QT, the grids don't change when I click BACK. I've tried different things for the last three hours, to no avail. Any ideas? gridwindow.cpp - My problem should be in here somewhere. Probably the handleBack() func. #include <iostream> #include "gridwindow.h" using namespace std; // Constructor for window. It constructs the three portions of the GUI and lays them out vertically. GridWindow::GridWindow(QWidget *parent,int rows,int cols) : QWidget(parent) { QHBoxLayout *header = setupHeader(); // Setup the title at the top. QGridLayout *grid = setupGrid(rows,cols); // Setup the grid of colored cells in the middle. QHBoxLayout *buttonRow = setupButtonRow(); // Setup the row of buttons across the bottom. QVBoxLayout *layout = new QVBoxLayout(); // Puts everything together. layout->addLayout(header); layout->addLayout(grid); layout->addLayout(buttonRow); setLayout(layout); } // Destructor. GridWindow::~GridWindow() { delete title; } // Builds header section of the GUI. QHBoxLayout* GridWindow::setupHeader() { QHBoxLayout *header = new QHBoxLayout(); // Creates horizontal box. header->setAlignment(Qt::AlignHCenter); this->title = new QLabel("CONWAY'S GAME OF LIFE",this); // Creates big, bold, centered label (title): "Conway's Game of Life." this->title->setAlignment(Qt::AlignHCenter); this->title->setFont(QFont("Arial", 32, QFont::Bold)); header->addWidget(this->title); // Adds widget to layout. return header; // Returns header to grid window. } // Builds the grid of cells. This method populates the grid's 2D array of GridCells with MxN cells. QGridLayout* GridWindow::setupGrid(int rows,int cols) { isRunning = false; QGridLayout *grid = new QGridLayout(); // Creates grid layout. grid->setHorizontalSpacing(0); // No empty spaces. Cells should be contiguous. grid->setVerticalSpacing(0); grid->setSpacing(0); grid->setAlignment(Qt::AlignHCenter); for(int i=0; i < rows; i++) //Each row is a vector of grid cells. { std::vector<GridCell*> row; // Creates new vector for current row. cells.push_back(row); for(int j=0; j < cols; j++) { GridCell *cell = new GridCell(); // Creates and adds new cell to row. cells.at(i).push_back(cell); grid->addWidget(cell,i,j); // Adds to cell to grid layout. Column expands vertically. grid->setColumnStretch(j,1); } grid->setRowStretch(i,1); // Sets row expansion horizontally. } return grid; // Returns grid. } // Builds footer section of the GUI. QHBoxLayout* GridWindow::setupButtonRow() { QHBoxLayout *buttonRow = new QHBoxLayout(); // Creates horizontal box for buttons. buttonRow->setAlignment(Qt::AlignHCenter); // Clear Button - Clears cell; sets them all to DEAD/white. QPushButton *clearButton = new QPushButton("CLEAR"); clearButton->setFixedSize(100,25); connect(clearButton, SIGNAL(clicked()), this, SLOT(handlePause())); // Pauses timer before clearing. connect(clearButton, SIGNAL(clicked()), this, SLOT(handleClear())); // Connects to clear function to make all cells DEAD/white. buttonRow->addWidget(clearButton); // Forward Button - Steps one step forward. QPushButton *forwardButton = new QPushButton("FORWARD"); forwardButton->setFixedSize(100,25); connect(forwardButton, SIGNAL(clicked()), this, SLOT(handleForward())); // Signals to handleForward function.. buttonRow->addWidget(forwardButton); // Back Button - Steps one step backward. QPushButton *backButton = new QPushButton("BACK"); backButton->setFixedSize(100,25); connect(backButton, SIGNAL(clicked()), this, SLOT(handleBack())); // Signals to handleBack funciton. buttonRow->addWidget(backButton); // Start Button - Starts game when user clicks. Or, resumes game after being paused. QPushButton *startButton = new QPushButton("START/RESUME"); startButton->setFixedSize(100,25); connect(startButton, SIGNAL(clicked()), this, SLOT(handlePause())); // Deletes current timer if there is one. Then restarts everything. connect(startButton, SIGNAL(clicked()), this, SLOT(handleStart())); // Signals to handleStart function. buttonRow->addWidget(startButton); // Pause Button - Pauses simulation of game. QPushButton *pauseButton = new QPushButton("PAUSE"); pauseButton->setFixedSize(100,25); connect(pauseButton, SIGNAL(clicked()), this, SLOT(handlePause())); // Signals to pause function which pauses timer. buttonRow->addWidget(pauseButton); // Quit Button - Exits program. QPushButton *quitButton = new QPushButton("EXIT"); quitButton->setFixedSize(100,25); connect(quitButton, SIGNAL(clicked()), qApp, SLOT(quit())); // Signals the quit slot which ends the program. buttonRow->addWidget(quitButton); return buttonRow; // Returns bottom of layout. } /* SLOT method for handling clicks on the "clear" button. Receives "clicked" signals on the "Clear" button and sets all cells to DEAD. */ void GridWindow::handleClear() { for(unsigned int row=0; row < cells.size(); row++) // Loops through current rows' cells. { for(unsigned int col=0; col < cells[row].size(); col++) // Loops through the rows'columns' cells. { GridCell *cell = cells[row][col]; // Grab the current cell & set its value to dead. cell->setType(DEAD); } } } /* SLOT method for handling clicks on the "start" button. Receives "clicked" signals on the "start" button and begins game simulation. */ void GridWindow::handleStart() { isRunning = true; // It is running. Sets isRunning to true. this->timer = new QTimer(this); // Creates new timer. connect(this->timer, SIGNAL(timeout()), this, SLOT(timerFired())); // Connect "timerFired" method class to the "timeout" signal fired by the timer. this->timer->start(500); // Timer to fire every 500 milliseconds. } /* SLOT method for handling clicks on the "pause" button. Receives "clicked" signals on the "pause" button and stops the game simulation. */ void GridWindow::handlePause() { if(isRunning) // If it is running... this->timer->stop(); // Stops the timer. isRunning = false; // Set to false. } void GridWindow::handleForward() { if(isRunning); // If it's running, do nothing. else timerFired(); // It not running, step forward one step. } void GridWindow::handleBack() { std::vector<std::vector<GridCell*> > cells2; if(isRunning); // If it's running, do nothing. else if(backStack.empty()) cout << "EMPTYYY" << endl; else { cells2 = backStack.peek(); for (unsigned int f = 0; f < cells.size(); f++) // Loop through cells' rows. { for (unsigned int g = 0; g < cells.at(f).size(); g++) // Loop through cells columns. { cells[f][g]->setType(cells2[f][g]->getType()); // Set cells[f][g]'s type to cells2[f][g]'s type. } } cout << "PRE=POP" << endl; backStack.pop(); cout << "OYYYY" << endl; } } // Accessor method - Gets the 2D vector of grid cells. std::vector<std::vector<GridCell*> >& GridWindow::getCells() { return this->cells; } /* TimerFired function: 1) 2D-Vector cells2 is declared. 2) cells2 is initliazed with loops/push_backs so that all its cells are DEAD. 3) We loop through cells, and count the number of LIVE neighbors next to a given cell. --> Depending on how many cells are living, we choose if the cell should be LIVE or DEAD in the next simulation, according to the rules. -----> We save the cell type in cell2 at the same indice (the same row and column cell in cells2). 4) After check all the cells (and save the next round values in cells 2), we set cells's gridcells equal to cells2 gridcells. --> This causes the cells to be redrawn with cells2 types (white or black). */ void GridWindow::timerFired() { backStack.push(cells); std::vector<std::vector<GridCell*> > cells2; // Holds new values for 2D vector. These are the next simulation round of cell types. for(unsigned int i = 0; i < cells.size(); i++) // Loop through the rows of cells2. (Same size as cells' rows.) { vector<GridCell*> row; // Creates Gridcell* vector to push_back into cells2. cells2.push_back(row); // Pushes back row vectors into cells2. for(unsigned int j = 0; j < cells[i].size(); j++) // Loop through the columns (the cells in each row). { GridCell *cell = new GridCell(); // Creates new GridCell. cell->setType(DEAD); // Sets cell type to DEAD/white. cells2.at(i).push_back(cell); // Pushes back the DEAD cell into cells2. } // This makes a gridwindow the same size as cells with all DEAD cells. } for (unsigned int m = 0; m < cells.size(); m++) // Loop through cells' rows. { for (unsigned int n = 0; n < cells.at(m).size(); n++) // Loop through cells' columns. { unsigned int neighbors = 0; // Counter for number of LIVE neighbors for a given cell. // We know check all different variations of cells[i][j] to count the number of living neighbors for each cell. // We check m > 0 and/or n > 0 to make sure we don't access negative indexes (ex: cells[-1][0].) // We check m < size to make sure we don't try to access rows out of the vector (ex: row 5, if only 4 rows). // We check n < row size to make sure we don't access column item out of the vector (ex: 10th item in a column of only 9 items). // If we find that the Type = 1 (it is LIVE), then we add 1 to the neighbor. // Else - we add nothing to the neighbor counter. // Neighbor is the number of LIVE cells next to the current cell. if(m > 0 && n > 0) { if (cells[m-1][n-1]->getType() == 1) neighbors += 1; } if(m > 0) { if (cells[m-1][n]->getType() == 1) neighbors += 1; if(n < (cells.at(m).size() - 1)) { if (cells[m-1][n+1]->getType() == 1) neighbors += 1; } } if(n > 0) { if (cells[m][n-1]->getType() == 1) neighbors += 1; if(m < (cells.size() - 1)) { if (cells[m+1][n-1]->getType() == 1) neighbors += 1; } } if(n < (cells.at(m).size() - 1)) { if (cells[m][n+1]->getType() == 1) neighbors += 1; } if(m < (cells.size() - 1)) { if (cells[m+1][n]->getType() == 1) neighbors += 1; } if(m < (cells.size() - 1) && n < (cells.at(m).size() - 1)) { if (cells[m+1][n+1]->getType() == 1) neighbors += 1; } // Done checking number of neighbors for cells[m][n] // Now we change cells2 if it should switch in the next simulation step. // cells2 holds the values of what cells should be on the next iteration of the game. // We can't change cells right now, or it would through off our other cell values. // Apply game rules to cells: Create new, updated grid with the roundtwo vector. // Note - LIVE is 1; DEAD is 0. if (cells[m][n]->getType() == 1 && neighbors < 2) // If cell is LIVE and has less than 2 LIVE neighbors -> Set to DEAD. cells2[m][n]->setType(DEAD); else if (cells[m][n]->getType() == 1 && neighbors > 3) // If cell is LIVE and has more than 3 LIVE neighbors -> Set to DEAD. cells2[m][n]->setType(DEAD); else if (cells[m][n]->getType() == 1 && (neighbors == 2 || neighbors == 3)) // If cell is LIVE and has 2 or 3 LIVE neighbors -> Set to LIVE. cells2[m][n]->setType(LIVE); else if (cells[m][n]->getType() == 0 && neighbors == 3) // If cell is DEAD and has 3 LIVE neighbors -> Set to LIVE. cells2[m][n]->setType(LIVE); } } // Now we've gone through all of cells, and saved the new values in cells2. // Now we loop through cells and set all the cells' types to those of cells2. for (unsigned int f = 0; f < cells.size(); f++) // Loop through cells' rows. { for (unsigned int g = 0; g < cells.at(f).size(); g++) // Loop through cells columns. { cells[f][g]->setType(cells2[f][g]->getType()); // Set cells[f][g]'s type to cells2[f][g]'s type. } } } stack.h - Here's my stack. #ifndef STACK_H_ #define STACK_H_ #include <iostream> #include "node.h" template <typename T> class Stack { private: Node<T>* top; int listSize; public: Stack(); int size() const; bool empty() const; void push(const T& value); void pop(); T& peek() const; }; template <typename T> Stack<T>::Stack() : top(NULL) { listSize = 0; } template <typename T> int Stack<T>::size() const { return listSize; } template <typename T> bool Stack<T>::empty() const { if(listSize == 0) return true; else return false; } template <typename T> void Stack<T>::push(const T& value) { Node<T>* newOne = new Node<T>(value); newOne->next = top; top = newOne; listSize++; } template <typename T> void Stack<T>::pop() { Node<T>* oldT = top; top = top->next; delete oldT; listSize--; } template <typename T> T& Stack<T>::peek() const { return top->data; // Returns data in top item. } #endif gridcell.cpp - Gridcell implementation #include <iostream> #include "gridcell.h" using namespace std; // Constructor: Creates a grid cell. GridCell::GridCell(QWidget *parent) : QFrame(parent) { this->type = DEAD; // Default: Cell is DEAD (white). setFrameStyle(QFrame::Box); // Set the frame style. This is what gives each box its black border. this->button = new QPushButton(this); //Creates button that fills entirety of each grid cell. this->button->setSizePolicy(QSizePolicy::Expanding,QSizePolicy::Expanding); // Expands button to fill space. this->button->setMinimumSize(19,19); //width,height // Min height and width of button. QHBoxLayout *layout = new QHBoxLayout(); //Creates a simple layout to hold our button and add the button to it. layout->addWidget(this->button); setLayout(layout); layout->setStretchFactor(this->button,1); // Lets the buttons expand all the way to the edges of the current frame with no space leftover layout->setContentsMargins(0,0,0,0); layout->setSpacing(0); connect(this->button,SIGNAL(clicked()),this,SLOT(handleClick())); // Connects clicked signal with handleClick slot. redrawCell(); // Calls function to redraw (set new type for) the cell. } // Basic destructor. GridCell::~GridCell() { delete this->button; } // Accessor for the cell type. CellType GridCell::getType() const { return(this->type); } // Mutator for the cell type. Also has the side effect of causing the cell to be redrawn on the GUI. void GridCell::setType(CellType type) { this->type = type; redrawCell(); // Sets type and redraws cell. } // Handler slot for button clicks. This method is called whenever the user clicks on this cell in the grid. void GridCell::handleClick() { // When clicked on... if(this->type == DEAD) // If type is DEAD (white), change to LIVE (black). type = LIVE; else type = DEAD; // If type is LIVE (black), change to DEAD (white). setType(type); // Sets new type (color). setType Calls redrawCell() to recolor. } // Method to check cell type and return the color of that type. Qt::GlobalColor GridCell::getColorForCellType() { switch(this->type) { default: case DEAD: return Qt::white; case LIVE: return Qt::black; } } // Helper method. Forces current cell to be redrawn on the GUI. Called whenever the setType method is invoked. void GridCell::redrawCell() { Qt::GlobalColor gc = getColorForCellType(); //Find out what color this cell should be. this->button->setPalette(QPalette(gc,gc)); //Force the button in the cell to be the proper color. this->button->setAutoFillBackground(true); this->button->setFlat(true); //Force QT to NOT draw the borders on the button } Thanks a lot. Let me know if you need anything else.

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• Checking if an int is prime more efficiently

  - by SipSop

  I recently was part of a small java programming competition at my school. My partner and I have just finished our first pure oop class and most of the questions were out of our league so we settled on this one (and I am paraphrasing somewhat): "given an input integer n return the next int that is prime and its reverse is also prime for example if n = 18 your program should print 31" because 31 and 13 are both prime. Your .class file would then have a test case of all the possible numbers from 1-2,000,000,000 passed to it and it had to return the correct answer within 10 seconds to be considered valid. We found a solution but with larger test cases it would take longer than 10 seconds. I am fairly certain there is a way to move the range of looping from n,..2,000,000,000 down as the likely hood of needing to loop that far when n is a low number is small, but either way we broke the loop when a number is prime under both conditions is found. At first we were looping from 2,..n no matter how large it was then i remembered the rule about only looping to the square root of n. Any suggestions on how to make my program more efficient? I have had no classes dealing with complexity analysis of algorithms. Here is our attempt. public class P3 { public static void main(String[] args){ long loop = 2000000000; long n = Integer.parseInt(args[0]); for(long i = n; i<loop; i++) { String s = i +""; String r = ""; for(int j = s.length()-1; j>=0; j--) r = r + s.charAt(j); if(prime(i) && prime(Long.parseLong(r))) { System.out.println(i); break; } } System.out.println("#"); } public static boolean prime(long p){ for(int i = 2; i<(int)Math.sqrt(p); i++) { if(p%i==0) return false; } return true; } } ps sorry if i did the formatting for code wrong this is my first time posting here. Also the output had to have a '#' after each line thats what the line after the loop is about Thanks for any help you guys offer!!!

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• Error in Print Function in Bubble Sort MIPS?

  - by m00nbeam360

  Sorry that this is such a long block of code, but do you see any obvious syntax errors in this? I feel like the problem is that the code isn't printing correctly since the sort and swap methods were from my textbook. Please help if you can! .data save: .word 1,2,4,2,5,6 size: .word 6 .text swap: sll $t1, $a1, 2 #shift bits by 2 add $t1, $a1, $t1 #set $t1 address to v[k] lw $t0, 0($t1) #load v[k] into t1 lw $t2, 4($t1) #load v[k+1] into t1 sw $t2, 0($t1) #swap addresses sw $t0, 4($t1) #swap addresses jr $ra #return sort: addi $sp, $sp, -20 #make enough room on the stack for five registers sw $ra, 16($sp) #save the return address on the stack sw $s3, 12($sp) #save $s3 on the stack sw $s2, 8($sp) #save Ss2 on the stack sw $s1, 4($sp) #save $s1 on the stack sw $s0, 0($sp) #save $s0 on the stack move $s2, $a0 #copy the parameter $a0 into $s2 (save $a0) move $s3, $a1 #copy the parameter $a1 into $s3 (save $a1) move $s0, $zero #start of for loop, i = 0 for1tst: slt $t0, $s0, $s3 #$t0 = 0 if $s0 S $s3 (i S n) beq $t0, $zero, exit1 #go to exit1 if $s0 S $s3 (i S n) addi $s1, $s0, -1 #j - i - 1 for2tst: slti $t0, $s1, 0 #$t0 = 1 if $s1 < 0 (j < 0) bne $t0, $zero, exit2 #$t0 = 1 if $s1 < 0 (j < 0) sll $t1, $s1, 2 #$t1 = j * 4 (shift by 2 bits) add $t2, $s2, $t1 #$t2 = v + (j*4) lw $t3, 0($t2) #$t3 = v[j] lw $t4, 4($t2) #$t4 = v[j+1] slt $t0, $t4, $t3 #$t0 = 0 if $t4 S $t3 beq $t0, $zero, exit2 #go to exit2 if $t4 S $t3 move $a0, $s2 #1st parameter of swap is v(old $a0) move $a1, $s1 #2nd parameter of swap is j jal swap #swap addi $s1, $s1, -1 j for2tst #jump to test of inner loop j print exit2: addi $s0, $s0, 1 #i = i + 1 j for1tst #jump to test of outer loop exit1: lw $s0, 0($sp) #restore $s0 from stack lw $s1, 4($sp) #resture $s1 from stack lw $s2, 8($sp) #restore $s2 from stack lw $s3, 12($sp) #restore $s3 from stack lw $ra, 16($sp) #restore $ra from stack addi $sp, $sp, 20 #restore stack pointer jr $ra #return to calling routine .data space:.asciiz " " # space to insert between numbers head: .asciiz "The sorted numbers are:\n" .text print:add $t0, $zero, $a0 # starting address of array add $t1, $zero, $a1 # initialize loop counter to array size la $a0, head # load address of print heading li $v0, 4 # specify Print String service syscall # print heading out: lw $a0, 0($t0) # load fibonacci number for syscall li $v0, 1 # specify Print Integer service syscall # print fibonacci number la $a0, space # load address of spacer for syscall li $v0, 4 # specify Print String service syscall # output string addi $t0, $t0, 4 # increment address addi $t1, $t1, -1 # decrement loop counter bgtz $t1, out # repeat if not finished jr $ra # return

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• node.js callback getting unexpected value for variable

  - by defrex

  I have a for loop, and inside it a variable is assigned with var. Also inside the loop a method is called which requires a callback. Inside the callback function I'm using the variable from the loop. I would expect that it's value, inside the callback function, would be the same as it was outside the callback during that iteration of the loop. However, it always seems to be the value from the last iteration of the loop. Am I misunderstanding scope in JavaScript, or is there something else wrong? The program in question here is a node.js app that will monitor a working directory for changes and restart the server when it finds one. I'll include all of the code for the curious, but the important bit is the parse_file_list function. var posix = require('posix'); var sys = require('sys'); var server; var child_js_file = process.ARGV[2]; var current_dir = __filename.split('/'); current_dir = current_dir.slice(0, current_dir.length-1).join('/'); var start_server = function(){ server = process.createChildProcess('node', [child_js_file]); server.addListener("output", function(data){sys.puts(data);}); }; var restart_server = function(){ sys.puts('change discovered, restarting server'); server.close(); start_server(); }; var parse_file_list = function(dir, files){ for (var i=0;i<files.length;i++){ var file = dir+'/'+files[i]; sys.puts('file assigned: '+file); posix.stat(file).addCallback(function(stats){ sys.puts('stats returned: '+file); if (stats.isDirectory()) posix.readdir(file).addCallback(function(files){ parse_file_list(file, files); }); else if (stats.isFile()) process.watchFile(file, restart_server); }); } }; posix.readdir(current_dir).addCallback(function(files){ parse_file_list(current_dir, files); }); start_server(); The output from this is: file assigned: /home/defrex/code/node/ejs.js file assigned: /home/defrex/code/node/templates file assigned: /home/defrex/code/node/web file assigned: /home/defrex/code/node/server.js file assigned: /home/defrex/code/node/settings.js file assigned: /home/defrex/code/node/apps file assigned: /home/defrex/code/node/dev_server.js file assigned: /home/defrex/code/node/main_urls.js stats returned: /home/defrex/code/node/main_urls.js stats returned: /home/defrex/code/node/main_urls.js stats returned: /home/defrex/code/node/main_urls.js stats returned: /home/defrex/code/node/main_urls.js stats returned: /home/defrex/code/node/main_urls.js stats returned: /home/defrex/code/node/main_urls.js stats returned: /home/defrex/code/node/main_urls.js stats returned: /home/defrex/code/node/main_urls.js For those from the future: node.devserver.js

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• SQL SERVER – Data Pages in Buffer Pool – Data Stored in Memory Cache

  - by pinaldave

  This will drop all the clean buffers so we will be able to start again from there. Now, run the following script and check the execution plan of the query. Have you ever wondered what types of data are there in your cache? During SQL Server Trainings, I am usually asked if there is any way one can know how much data in a table is stored in the memory cache? The more detailed question I usually get is if there are multiple indexes on table (and used in a query), were the data of the single table stored multiple times in the memory cache or only for a single time? Here is a query you can run to figure out what kind of data is stored in the cache. USE AdventureWorks GO SELECT COUNT(*) AS cached_pages_count, name AS BaseTableName, IndexName, IndexTypeDesc FROM sys.dm_os_buffer_descriptors AS bd INNER JOIN ( SELECT s_obj.name, s_obj.index_id, s_obj.allocation_unit_id, s_obj.OBJECT_ID, i.name IndexName, i.type_desc IndexTypeDesc FROM ( SELECT OBJECT_NAME(OBJECT_ID) AS name, index_id ,allocation_unit_id, OBJECT_ID FROM sys.allocation_units AS au INNER JOIN sys.partitions AS p ON au.container_id = p.hobt_id AND (au.type = 1 OR au.type = 3) UNION ALL SELECT OBJECT_NAME(OBJECT_ID) AS name, index_id, allocation_unit_id, OBJECT_ID FROM sys.allocation_units AS au INNER JOIN sys.partitions AS p ON au.container_id = p.partition_id AND au.type = 2 ) AS s_obj LEFT JOIN sys.indexes i ON i.index_id = s_obj.index_id AND i.OBJECT_ID = s_obj.OBJECT_ID ) AS obj ON bd.allocation_unit_id = obj.allocation_unit_id WHERE database_id = DB_ID() GROUP BY name, index_id, IndexName, IndexTypeDesc ORDER BY cached_pages_count DESC; GO Now let us run the query above and observe the output of the same. We can see in the above query that there are four columns. Cached_Pages_Count lists the pages cached in the memory. BaseTableName lists the original base table from which data pages are cached. IndexName lists the name of the index from which pages are cached. IndexTypeDesc lists the type of index. Now, let us do one more experience here. Please note that you should not run this test on a production server as it can extremely reduce the performance of the database. DBCC DROPCLEANBUFFERS This will drop all the clean buffers and we will be able to start again from there. Now run following script and check the execution plan for the same. USE AdventureWorks GO SELECT UnitPrice, ModifiedDate FROM Sales.SalesOrderDetail WHERE SalesOrderDetailID BETWEEN 1 AND 100 GO The execution plans contain the usage of two different indexes. Now, let us run the script that checks the pages cached in SQL Server. It will give us the following output. It is clear from the Resultset that when more than one index is used, datapages related to both or all of the indexes are stored in Memory Cache separately. Let me know what you think of this article. I had a great pleasure while writing this article because I was able to write on this subject, which I like the most. In the next article, we will exactly see what data are cached and those that are not cached, using a few undocumented commands. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: DMV, Pinal Dave, SQL, SQL Authority, SQL Optimization, SQL Query, SQL Scripts, SQL Server, SQL Tips and Tricks, T SQL, Technology Tagged: SQL DMV

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• SQL SERVER – Quiz and Video – Introduction to Hierarchical Query using a Recursive CTE

  - by pinaldave

  This blog post is inspired from SQL Queries Joes 2 Pros: SQL Query Techniques For Microsoft SQL Server 2008 – SQL Exam Prep Series 70-433 – Volume 2.[Amazon] | [Flipkart] | [Kindle] | [IndiaPlaza] This is follow up blog post of my earlier blog post on the same subject - SQL SERVER – Introduction to Hierarchical Query using a Recursive CTE – A Primer. In the article we discussed various basics terminology of the CTE. The article further covers following important concepts of common table expression. What is a Common Table Expression (CTE) Building a Recursive CTE Identify the Anchor and Recursive Query Add the Anchor and Recursive query to a CTE Add an expression to track hierarchical level Add a self-referencing INNER JOIN statement Above six are the most important concepts related to CTE and SQL Server.  There are many more things one has to learn but without beginners fundamentals one can’t learn the advanced  concepts. Let us have small quiz and check how many of you get the fundamentals right. Quiz 1) You have an employee table with the following data. EmpID FirstName LastName MgrID 1 David Kennson 11 2 Eric Bender 11 3 Lisa Kendall 4 4 David Lonning 11 5 John Marshbank 4 6 James Newton 3 7 Sally Smith NULL You need to write a recursive CTE that shows the EmpID, FirstName, LastName, MgrID, and employee level. The CEO should be listed at Level 1. All people who work for the CEO will be listed at Level 2. All of the people who work for those people will be listed at Level 3. Which CTE code will achieve this result? WITH EmpList AS (SELECT Boss.EmpID, Boss.FName, Boss.LName, Boss.MgrID, 1 AS Lvl FROM Employee AS Boss WHERE Boss.MgrID IS NULL UNION ALL SELECT E.EmpID, E.FirstName, E.LastName, E.MgrID, EmpList.Lvl + 1 FROM Employee AS E INNER JOIN EmpList ON E.MgrID = EmpList.EmpID) SELECT * FROM EmpList WITH EmpListAS (SELECT EmpID, FirstName, LastName, MgrID, 1 as Lvl FROM Employee WHERE MgrID IS NULL UNION ALL SELECT EmpID, FirstName, LastName, MgrID, 2 as Lvl ) SELECT * FROM BossList WITH EmpList AS (SELECT EmpID, FirstName, LastName, MgrID, 1 as Lvl FROM Employee WHERE MgrID is NOT NULL UNION SELECT EmpID, FirstName, LastName, MgrID, BossList.Lvl + 1 FROM Employee INNER JOIN EmpList BossList ON Employee.MgrID = BossList.EmpID) SELECT * FROM EmpList 2) You have a table named Employee. The EmployeeID of each employee’s manager is in the ManagerID column. You need to write a recursive query that produces a list of employees and their manager. The query must also include the employee’s level in the hierarchy. You write the following code segment: WITH EmployeeList (EmployeeID, FullName, ManagerName, Level) AS ( –PICK ANSWER CODE HERE ) SELECT EmployeeID, FullName, ” AS [ManagerID], 1 AS [Level] FROM Employee WHERE ManagerID IS NULL UNION ALL SELECT emp.EmployeeID, emp.FullName mgr.FullName, 1 + 1 AS [Level] FROM Employee emp JOIN Employee mgr ON emp.ManagerID = mgr.EmployeeId SELECT EmployeeID, FullName, ” AS [ManagerID], 1 AS [Level] FROM Employee WHERE ManagerID IS NULL UNION ALL SELECT emp.EmployeeID, emp.FullName, mgr.FullName, mgr.Level + 1 FROM EmployeeList mgr JOIN Employee emp ON emp.ManagerID = mgr.EmployeeId Now make sure that you write down all the answers on the piece of paper. Watch following video and read earlier article over here. If you want to change the answer you still have chance. Solution 1) 1 2) 2 Now compare let us check the answers and compare your answers to following answers. I am very confident you will get them correct. Available at USA: Amazon India: Flipkart | IndiaPlaza Volume: 1, 2, 3, 4, 5 Please leave your feedback in the comment area for the quiz and video. Did you know all the answers of the quiz? Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: Joes 2 Pros, PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology

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• How does interpolation actually work to smooth out an object's movement?

  - by user22241

  I've asked a few similar questions over the past 8 months or so with no real joy, so I am going make the question more general. I have an Android game which is OpenGL ES 2.0. within it I have the following Game Loop: My loop works on a fixed time step principle (dt = 1 / ticksPerSecond) loops=0; while(System.currentTimeMillis() > nextGameTick && loops < maxFrameskip){ updateLogic(dt); nextGameTick+=skipTicks; timeCorrection += (1000d/ticksPerSecond) % 1; nextGameTick+=timeCorrection; timeCorrection %=1; loops++; } render(); My intergration works like this: sprite.posX+=sprite.xVel*dt; sprite.posXDrawAt=sprite.posX*width; Now, everything works pretty much as I would like. I can specify that I would like an object to move across a certain distance (screen width say) in 2.5 seconds and it will do just that. Also because of the frame skipping that I allow in my game loop, I can do this on pretty much any device and it will always take 2.5 seconds. Problem However, the problem is that when a render frame skips, the graphic stutter. It's extremely annoying. If I remove the ability to skip frames, then everything is smooth as you like, but will run at different speeds on different devices. So it's not an option. I'm still not sure why the frame skips, but I would like to point out that this is Nothing to do with poor performance, I've taken the code right back to 1 tiny sprite and no logic (apart from the logic required to move the sprite) and I still get skipped frames. And this is on a Google Nexus 10 tablet (and as mentioned above, I need frame skipping to keep the speed consistent across devices anyway). So, the only other option I have is to use interpolation (or extrapolation), I've read every article there is out there but none have really helped me to understand how it works and all of my attempted implementations have failed. Using one method I was able to get things moving smoothly but it was unworkable because it messed up my collision. I can foresee the same issue with any similar method because the interpolation is passed to (and acted upon within) the rendering method - at render time. So if Collision corrects position (character now standing right next to wall), then the renderer can alter it's position and draw it in the wall. So I'm really confused. People have said that you should never alter an object's position from within the rendering method, but all of the examples online show this. So I'm asking for a push in the right direction, please do not link to the popular game loop articles (deWitters, Fix your timestep, etc) as I've read these multiple times. I'm not asking anyone to write my code for me. Just explain please in simple terms how Interpolation actually works with some examples. I will then go and try to integrate any ideas into my code and will ask more specific questions if need-be further down the line. (I'm sure this is a problem many people struggle with).

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• Hijax == sneaky Javascript redirects? Will I get banned from Google?

  - by Chris Jacob

  Question Will I get penalised as "sneaky Javascript redirects" by Google if I have the following Hijax setup (which requires a JavaScript redirect on the page indexed by google). Goal I want to implement Hijax to enable AJAX content to be accessibile to non-JavaScript users and search engine crawlers. Background I'm working on a static file server (GitHub Pages). No server side tricks allowed (so Google's #! "hash bang" solution is not an option). I'm trying to keep my files DRY. I don't want to repeat the common OUTER template in all my files i.e. header, navigation menu, footer, etc They will live in the main index.html Setup the Hijax index.html page contains all OUTER html/css/js... the site's template. index.html has a <div id="content"> which defaults to containing the "homepage" html. index.html has a navigation menu, with a Hijax link to an "about" page. With JavaScript disabled (e.g. crawler) it follows link to /about.html. With JavaScript enabled (e.g. most people) the link updates the url hash fragment to /#about and jQuery replaces the <div id="content"> innerHTML with $("#content").load("about.html #inner-container");. AJAX content about.html does not contain anything extra to try an cloak content for crawlers. about.html file contains enough HTML / CSS / JavaScript to display /about.html as a standalone page with it's own META data... e.g. <html><head><title>About</title>...</head><body></body></html>. about.html has NO OUTER HTML template (i.e. header, navigation menu, footer, etc). about.html <body> contains a <div id="inner-container"> which holds the content that is injected into index.html. about.html has a <noscript> tag as the first child of <body> which explains to non-JavaScript users that they are viewing the about page "inner content" - with a link to navigate to the index.html page to get the full page layout with menu. The (Sneaky?) Redirect Google indexes the /about.html page. However when a person with JavaScript enabled visits that page there is no OUTER html template (e.g. header, navigation menu, footer, etc). So I need to do a JavaScript redirect to get the person over the /#about page (deeplinking to the "about" page "state" in index.html). I'm thinking of doing a "redirect on click or after 10 seconds". The end results is that user ends up on an "enhanced" page back on index.html with all it's OUTER template - but the core "page" content is practically identical. Known issue with inbound links e.g. Share / Bookmarking It seems that if a user shares the URL /#about on their blog, when allocating inbound links to my site Google ignores everything after the # ... it allocates value to the / page - See: http://stackoverflow.com/questions/5028405/hashbang-vs-hijax/5166665#5166665. I can only try an minimise this issue offering "share" buttons on the page with the appropriate urls i.e. /about.html. Duplicate Sorry. I posted this same question over on http://stackoverflow.com/questions/5561686/hijax-sneaky-javascript-redirects-will-i-get-banned-from-google ... then realised it probably belongs more on this Stack Exchange site... Not sure if I should delete the Stack Overflow question? Or just leave it on both sites? Please leave comment.

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• Writing a method to 'transform' an immutable object: how should I approach this?

  - by Prog

  (While this question has to do with a concrete coding dilemma, it's mostly about what's the best way to design a function.) I'm writing a method that should take two Color objects, and gradually transform the first Color into the second one, creating an animation. The method will be in a utility class. My problem is that Color is an immutable object. That means that I can't do color.setRGB or color.setBlue inside a loop in the method. What I can do, is instantiate a new Color and return it from the method. But then I won't be able to gradually change the color. So I thought of three possible solutions: 1- The client code includes the method call inside a loop. For example: int duration = 1500; // duration of the animation in milliseconds int steps = 20; // how many 'cycles' the animation will take for(int i=0; i<steps; i++) color = transformColor(color, targetColor, duration, steps); And the method would look like this: Color transformColor(Color original, Color target, int duration, int steps){ int redDiff = target.getRed() - original.getRed(); int redAddition = redDiff / steps; int newRed = original.getRed() + redAddition; // same for green and blue .. Thread.sleep(duration / STEPS); // exception handling omitted return new Color(newRed, newGreen, newBlue); } The disadvantage of this approach is that the client code has to "do part of the method's job" and include a for loop. The method doesn't do it's work entirely on it's own, which I don't like. 2- Make a mutable Color subclass with methods such as setRed, and pass objects of this class into transformColor. Then it could look something like this: void transformColor(MutableColor original, Color target, int duration){ final int STEPS = 20; int redDiff = target.getRed() - original.getRed(); int redAddition = redDiff / steps; int newRed = original.getRed() + redAddition; // same for green and blue .. for(int i=0; i<STEPS; i++){ original.setRed(original.getRed() + redAddition); // same for green and blue .. Thread.sleep(duration / STEPS); // exception handling omitted } } Then the calling code would usually look something like this: // The method will usually transform colors of JComponents JComponent someComponent = ... ; // setting the Color in JComponent to be a MutableColor Color mutableColor = new MutableColor(someComponent.getForeground()); someComponent.setForeground(mutableColor); // later, transforming the Color in the JComponent transformColor((MutableColor)someComponent.getForeground(), new Color(200,100,150), 2000); The disadvantage is - the need to create a new class MutableColor, and also the need to do casting. 3- Pass into the method the actual mutable object that holds the color. Then the method could do object.setColor or similar every iteration of the loop. Two disadvantages: A- Not so elegant. Passing in the object that holds the color just to transform the color feels unnatural. B- While most of the time this method will be used to transform colors inside JComponent objects, other kinds of objects may have colors too. So the method would need to be overloaded to receive other types, or receive Objects and have instanceof checks inside.. Not optimal. Right now I think I like solution #2 the most, than solution #1 and solution #3 the least. However I'd like to hear your opinions and suggestions regarding this.

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• python sqlite3 won't execute a join, but sqlite3 alone will

  - by Francis Davey

  Using the sqlite3 standard library in python 2.6.4, the following query works fine on sqlite3 command line: select segmentid, node_t, start, number,title from ((segments inner join position using (segmentid)) left outer join titles using (legid, segmentid)) left outer join numbers using (start, legid, version); But If I execute it via the sqlite3 library in python I get an error: >>> conn=sqlite3.connect('data/test.db') >>> conn.execute('''select segmentid, node_t, start, number,title from ((segments inner join position using (segmentid)) left outer join titles using (legid, segmentid)) left outer join numbers using (start, legid, version)''') Traceback (most recent call last): File "<stdin>", line 1, in <module> sqlite3.OperationalError: cannot join using column start - column not present in both tables The (computed) table on the left hand side of the join appears to have the relevant column because if I check it by itself I get: >>> conn.execute('''select * from ((segments inner join position using (segmentid)) left outer join titles using (legid, segmentid)) limit 20''').description (('segmentid', None, None, None, None, None, None), ('html', None, None, None, None, None, None), ('node_t', None, None, None, None, None, None), ('legid', None, None, None, None, None, None), ('version', None, None, None, None, None, None), ('start', None, None, None, None, None, None), ('title', None, None, None, None, None, None)) My schema is: CREATE TABLE leg (legid integer primary key, t char(16), year char(16), no char(16)); CREATE TABLE numbers ( number char(16), legid integer, version integer, start integer, end integer, prev integer, prev_number char(16), next integer, next_number char(16), primary key (number, legid, version)); CREATE TABLE position ( segmentid integer, legid integer, version integer, start integer, primary key (segmentid, legid, version)); CREATE TABLE 'segments' (segmentid integer primary key, html text, node_t integer); CREATE TABLE titles (legid integer, segmentid integer, title text, primary key (legid, segmentid)); CREATE TABLE versions (legid integer, version integer, primary key (legid, version)); CREATE INDEX idx_numbers_start on numbers (legid, version, start); I am baffled as to what I am doing wrong. I have tried quitting/restarting both the python and sqlite command lines and can't see what I'm doing wrong. It may be completely obvious.

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• Slow query with unexpected index scan

  - by zerkms

  Hello I have this query: SELECT * FROM sample INNER JOIN test ON sample.sample_number = test.sample_number INNER JOIN result ON test.test_number = result.test_number WHERE sampled_date BETWEEN '2010-03-17 09:00' AND '2010-03-17 12:00' the biggest table here is RESULT, contains 11.1M records. The left 2 tables about 1M. this query works slowly (more than 10 minutes) and returns about 800 records. executing plan shows clustered index scan (over it's PRIMARY KEY (result.result_number, which actually doesn't take part in query)) over all 11M records. RESULT.TEST_NUMBER is a clustered primary key. if I change 2010-03-17 09:00 to 2010-03-17 10:00 - i get about 40 records. it executes for 300ms. and plan shows index seek (over result.test_number index) if i replace * in SELECT clause to result.test_number (covered with index) - then all become fast in first case too. this points to hdd IO issues, but doesn't clarifies changing plan. so, any ideas? UPDATE: sampled_date is in table sample and covered by index. other fields from this query: test.sample_number is covered by index and result.test_number too. UPDATE 2: obviously than sql server in any reasons don't want to use index. i did a small experiment: i remove INNER JOIN with result, select all test.test_number and after that do SELECT * FROM RESULT WHERE TEST_NUMBER IN (...) this, of course, works fast. but i cannot get what is the difference and why query optimizer choose such inappropriate way to select data in 1st case.

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• How can parallelism affect number of results?

  - by spender

  I have a fairly complex query that looks something like this: create table Items(SomeOtherTableID int,SomeField int) create table SomeOtherTable(Id int,GroupID int) with cte1 as ( select SomeOtherTableID,COUNT(*) SubItemCount from Items t where t.SomeField is not null group by SomeOtherTableID ),cte2 as ( select tc.SomeOtherTableID,ROW_NUMBER() over (partition by a.GroupID order by tc.SubItemCount desc) SubItemRank from Items t inner join SomeOtherTable a on a.Id=t.SomeOtherTableID inner join cte1 tc on tc.SomeOtherTableID=t.SomeOtherTableID where t.SomeField is not null ),cte3 as ( select SomeOtherTableID from cte2 where SubItemRank=1 ) select * from cte3 t1 inner join cte3 t2 on t1.SomeOtherTableID<t2.SomeOtherTableID option (maxdop 1) The query is such that cte3 is filled with 6222 distinct results. In the final select, I am performing a cross join on cte3 with itself, (so that I can compare every value in the table with every other value in the table at a later point). Notice the final line : option (maxdop 1) Apparently, this switches off parallelism. So, with 6222 results rows in cte3, I would expect (6222*6221)/2, or 19353531 results in the subsequent cross joining select, and with the final maxdop line in place, that is indeed the case. However, when I remove the maxdop line, the number of results jumps to 19380454. I have 4 cores on my dev box. WTF? Can anyone explain why this is? Do I need to reconsider previous queries that cross join in this way?

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• MS SQL SELECT stored procedure according to combobox.selectedvalue

  - by Jay

  Hello, In order to fill a datagridview according to the selectedvalue of a combobox I've tried creating a stored procedure. However, as I'm not 100% sure what I'm doing it, depending on the WHERE statement at the end of my stored procedure, either returns everything within the table or nothing at all. This is what's in my class: Public Function GetAankoopDetails(ByRef DisplayMember As String, ByRef ValueMember As String) As DataTable DisplayMember = "AankoopDetailsID" ValueMember = "AankoopDetailsID" If DS.Tables.Count > 0 Then DS.Tables.Remove(DT) End If DT = DAC.ExecuteDataTable(My.Resources.S_AankoopDetails, _Result, _ DAC.Parameter(Const_AankoopID, AankoopID), _ DAC.Parameter("@ReturnValue", 0)) DS.Tables.Add(DT) Return DT End Function Public Function GetAankoopDetails() As DataTable If DS.Tables.Count > 0 Then DS.Tables.Remove(DT) End If DT = DAC.ExecuteDataTable(My.Resources.S_AankoopDetails, _Result, _ DAC.Parameter(Const_AankoopID, AankoopID), _ DAC.Parameter("@ReturnValue", 0)) DS.Tables.Add(DT) Return DT End Function This is the function in the code behind the form I've written in order to fill the datagridview: Private Sub GridAankoopDetails_Fill() Try Me.Cursor = Cursors.WaitCursor dgvAankoopDetails.DataSource = Nothing _clsAankoopDetails.AankoopDetailsID = cboKeuze.SelectedValue dgvAankoopDetails.DataSource = _clsAankoopDetails.GetAankoopDetails Catch ex As Exception MessageBox.Show("An error occurred while trying to fill the data grid: " & ex.Message, "Oops!", MessageBoxButtons.OK) Finally Me.Cursor = Cursors.Default End Try End Sub And finally, this is my stored procedure: (do note that I'm not sure what I'm doing here) USE [Budget] GO /****** Object: StoredProcedure [dbo].[S_AankoopDetails] Script Date: 04/12/2010 03:10:52 ******/ SET ANSI_NULLS ON GO SET QUOTED_IDENTIFIER ON GO ALTER PROCEDURE [dbo].[S_AankoopDetails] ( @AankoopID int, @ReturnValue int output ) AS declare @Value int set @Value =@@rowcount if @Value = 0 begin SELECT dbo.tblAankoopDetails.AankoopDetailsID, dbo.tblAankoopDetails.AankoopID, dbo.tblAankoopDetails.ArtikelID, dbo.tblAankoopDetails.Aantal, dbo.tblAankoopDetails.Prijs, dbo.tblAankoopDetails.Korting, dbo.tblAankoopDetails.SoortKorting, dbo.tblAankoopDetails.UitgavenDeelGroepID FROM dbo.tblAankoopDetails INNER JOIN dbo.tblAankoop ON dbo.tblAankoopDetails.AankoopID = dbo.tblAankoop.AankoopID INNER JOIN dbo.tblArtikel ON dbo.tblAankoopDetails.ArtikelID = dbo.tblArtikel.ArtikelID INNER JOIN dbo.tblUitgavenDeelGroep ON dbo.tblAankoopDetails.UitgavenDeelGroepID = dbo.tblUitgavenDeelGroep.UitgavenDeelGroepID WHERE dbo.tblAankoopDetails.Deleted = 0 and dbo.tblAankoopDetails.AankoopID = @AankoopID ORDER BY AankoopID if @@rowcount >0 begin set @ReturnValue=999 end else begin set @ReturnValue=997 end end if @Value >0 begin --Dit wil zeggen dat ik een gebruiker wil ingeven die reeds bestaat. (998) set @ReturnValue=998 end Does anyone know what I'm need to do to resolve this? Kind regards, Jay

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• C# Static constructors design problem - need to specify parameter

  - by Neil Dobson

  I have a re-occurring design problem with certain classes which require one-off initialization with a parameter such as the name of an external resource such as a config file. For example, I have a corelib project which provides application-wide logging, configuration and general helper methods. This object could use a static constructor to initialize itself but it need access to a config file which it can't find itself. I can see a couple of solutions, but both of these don't seem quite right: 1) Use a constructor with a parameter. But then each object which requires corelib functionality should also know the name of the config file, so this has to be passed around the application. Also if I implemented corelib as a singleton I would also have to pass the config file as a parameter to the GetInstance method, which I believe is also not right. 2) Create a static property or method to pass through the config file or other external parameter. I have sort of used the latter method and created a Load method which initializes an inner class which it passes through the config file in the constructor. Then this inner class is exposed through a public property MyCoreLib. public static class CoreLib { private static MyCoreLib myCoreLib; public static void Load(string configFile) { myCoreLib = new MyCoreLib(configFile); } public static MyCoreLib MyCoreLib { get { return myCoreLib; } } public class MyCoreLib { private string configFile; public MyCoreLib(string configFile) { this.configFile = configFile; } public void DoSomething() { } } } I'm still not happy though. The inner class is not initialized until you call the load method, so that needs to be considered anywhere the MyCoreLib is accessed. Also there is nothing to stop someone calling the load method again. Any other patterns or ideas how to accomplish this?

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• Rails 3 - Category Filter Using Select - Load Partial Via Ajax

  - by fourfour

  Hey. I am trying to filter Client Comments by using a select and rendering it in a partial. Right now the partial loads @client.comments. I have a Category model with a Categorizations join. This all works, just need to know how to get the select to call the filter action and load the partial with ajax. Thanks for you help. Categories controller: def filter_category @categories = Category.all respond_to do |format| format.js # filter.rjs end end filter.js.erb: page.replace_html 'client-not-inner', :partial => 'comments', :locals => { :com => Category.first.comments } show.html.erb (clients) <% form_tag(filter_category_path(:id), :method => :put, :class => 'categories', :remote => true, :controller => 'categoires', :action => 'filter') do %> <label>Categories</label> <%= select_tag(:category, options_for_select(Category.all.map {|category| [category.name, category.id]}, @category_id)) %> <% end %> <div class="client-note-inner"> <%= render :partial => 'comments', :locals => { :com => @comments } %> </div><!--end client-note-inner--> Hope that makes sense. Cheers.

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• Iteration speed of int vs long

  - by jqno

  I have the following two programs: long startTime = System.currentTimeMillis(); for (int i = 0; i < N; i++); long endTime = System.currentTimeMillis(); System.out.println("Elapsed time: " + (endTime - startTime) + " msecs"); and long startTime = System.currentTimeMillis(); for (long i = 0; i < N; i++); long endTime = System.currentTimeMillis(); System.out.println("Elapsed time: " + (endTime - startTime) + " msecs"); Note: the only difference is the type of the loop variable (int and long). When I run this, the first program consistently prints between 0 and 16 msecs, regardless of the value of N. The second takes a lot longer. For N == Integer.MAX_VALUE, it runs in about 1800 msecs on my machine. The run time appears to be more or less linear in N. So why is this? I suppose the JIT-compiler optimizes the int loop to death. And for good reason, because obviously it doesn't do anything. But why doesn't it do so for the long loop as well? A colleague thought we might be measuring the JIT compiler doing its work in the long loop, but since the run time seems to be linear in N, this probably isn't the case.

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• JPA ManyToMany referencing issue

  - by dharga

  I have three tables. AvailableOptions and PlanTypeRef with a ManyToMany association table called AvailOptionPlanTypeAssoc. The trimmed down schemas look like this CREATE TABLE [dbo].[AvailableOptions]( [SourceApplication] [char](8) NOT NULL, [OptionId] [int] IDENTITY(1,1) NOT NULL, ... ) CREATE TABLE [dbo].[AvailOptionPlanTypeAssoc]( [SourceApplication] [char](8) NOT NULL, [OptionId] [int] NOT NULL, [PlanTypeCd] [char](2) NOT NULL, ) CREATE TABLE [dbo].[PlanTypeRef]( [PlanTypeCd] [char](2) NOT NULL, [PlanTypeDesc] [varchar](32) NOT NULL, ) And the Java code looks like this. //AvailableOption.java @ManyToMany(cascade={CascadeType.ALL}, fetch=FetchType.EAGER) @JoinTable( name = "AvailOptionPlanTypeAssoc", joinColumns = { @JoinColumn(name = "OptionId"), @JoinColumn(name="SourceApplication")}, inverseJoinColumns=@JoinColumn(name="PlanTypeCd")) List<PlanType> planTypes = new ArrayList<PlanType>(); //PlanType.java @ManyToMany @JoinTable( name = "AvailOptionPlanTypeAssoc", joinColumns = { @JoinColumn(name = "PlanTypeCd")}, inverseJoinColumns={@JoinColumn(name="OptionId"), @JoinColumn(name="SourceApplication")}) List<AvailableOption> options = new ArrayList<AvailableOption>(); The problem arises when making a select on AvailableOptions it joins back onto itself. Note the following SQL code from the backtrace. The second inner join should be on PlanTypeRef. SELECT t0.OptionId, t0.SourceApplication, t2.PlanTypeCd, t2.EffectiveDate, t2.PlanTypeDesc, t2.SysLstTrxDtm, t2.SysLstUpdtUserId, t2.TermDate FROM dbo.AvailableOptions t0 INNER JOIN dbo.AvailOptionPlanTypeAssoc t1 ON t0.OptionId = t1.OptionId AND t0.SourceApplication = t1.SourceApplication INNER JOIN dbo.AvailableOptions t2 ON t1.PlanTypeCd = t2.PlanTypeCd WHERE (t0.SourceApplication = ? AND t0.OptionType = ?) ORDER BY t0.OptionId ASC, t0.SourceApplication ASC [params=(String) testApp, (String) junit0]}

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