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• Can I get the amount of time for which a key is pressed on a keyboard

  - by Adi

  Dear all, I am working on a project in which I have to develop bio-passwords based on user's keystroke style. Suppose a user types a password for 20 times, his keystrokes are recorded, like holdtime : time for which a particular key is pressed. digraph time : time it takes to press a different key. suppose a user types a password " COMPUTER". I need to know the time for which every key is pressed. something like : holdtime for the above password is C-- 200ms O-- 130ms M-- 150ms P-- 175ms U-- 320ms T-- 230ms E-- 120ms R-- 300ms The rational behind this is , every user will have a different holdtime. Say a old person is typing the password, he will take more time then a student. And it will be unique to a particular person. To do this project, I need to record the time for each key pressed. I would greatly appreciate if anyone can guide me in how to get these times. Editing from here.. Language is not important, but I would prefer it in C. I am more interested in getting the dataset.

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• How to customize the printing while using Window.print ?

  - by Holicreature

  i want to print a invoice and i use a print.css by media=print and when i change the current stylesheet to print.css i could able to view what i should be printing without the titles and content left aligned. But still while i'm printing there is space in the top and left and its taking up whole a4 sheet and also the whole width of the page.. But i've defined a body width of just 550 px. While i view to print preview, it takes the whole width instead of taking up 1/3 of the width.. My print.css is body { width:550px; height:450px; color:#000000; margin:0; padding:0; word-spacing:1.1pt; font-family : "Times New Roman", Times, serif; font-size : 10px; text-align:left; } a { visibility :hidden; display : none; } input{ display : none; } table { margin: 1px; text-align:left; } #list,#head,#cont,#fotter,#oth,#links,#name,li,ul,ol { display : none; } I'm printing through browser using window.print, so is there any special configuration i need to do...?

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• I can't login to my Django app when debug is set to False

  - by Eric

  I have a very strange problem, and I don't know how to fix or debug it. Short Story: I get locked out of my Django app when Debug is set to False. Long story: Case 1 (the first time it happened): 1. I enter my login info, but It just redirects to the login page. 2. I restart the server, try to login, and it works fine, I get in. 3. a few hours later I come back, log out, try to log back in and I can't. It just redirects to the login page. Case 2 (I figure out how to provoke the login failure): 1. I restart the server and am able to login to the site. 2. I log in and log out several times, everything is fine. 3. I go to a non-existing page and get a server error. 4. I log out and try to log back in, and I can't, just get redirected back to the login page. Case 3 (I can't provoke the login failure with Debug set to True): 1. I restart the server and am able to login to the site. 2. I log in and log out several times, everything is fine. 3. I go to a non-existing page and get a traceback. 4. I log out and log back in, everything works. 5. I wait and play around with it and can't get the login to fail while in Debug mode. Please help!

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• Load PHP function with jQuery Ajax

  - by brandon14_99

  I have a file which is loaded at the top of my document, which is called Videos.php. Inside that file are several functions, such as getYoutubeVideos. On some pages, I need to call upon that function several times (up to 50), and it of course creates major lag on load times. So I have been trying to figure out how to call that function in, only when it is need (when someone clicks the show videos button). I have very little experience with jQuery's ajax abilities. I would like the ajax call to be made inside of something like this: jQuery('a[rel=VideoPreview1).click(function(){ jQuery ("a[rel=VideoPreview1]").hide(); jQuery ("a[rel=HideVideoPreview1]").show(); jQuery ("#VideoPreview1").show(); //AJAX STUFF HERE preventDefault(); }); Ok I have created this based on the responses, but it is still not working: jQuery Code: jQuery(document).ready(function(){ jQuery("a[rel=VideoPreview5]").click(function(){ jQuery("a[rel=VideoPreview5]").hide(); jQuery("a[rel=HideVideoPreview5]").show(); jQuery.post("/Classes/Video.php", {action: "getYoutubeVideos", artist: "Train", track: "Hey, Soul Sister"}, function(data){ jQuery("#VideoPreview5").html(data); }, 'json'); jQuery("#VideoPreview5").show(); preventDefault(); }); jQuery("a[rel=HideVideoPreview5]").click(function(){ jQuery("a[rel=VideoPreview5]").show(); jQuery("a[rel=HideVideoPreview5]").hide(); jQuery("#VideoPreview5").hide(); preventDefault(); }); }); And the PHP code: $Action = isset($_POST['action']); $Artist = isset($_POST['artist']); $Track = isset($_POST['track']); if($Action == 'getYoutubeVideos') { echo 'where are the videos'; echo json_encode(getYoutubeVideos($Artist.' '.$Track, 1, 5, 'relevance')); }

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• Java Concurrency in practice sample question

  - by andy boot

  I am reading "Java Concurrency in practice" and looking at the example code on page 51. This states that if a thread has references to a shared object then other threads may be able to access that object before the constructor has finished executing. I have tried to put this into practice and so I wrote this code thinking that if I ran it enough times a RuntimeException("World is f*cked") would occur. But it isn't doing. Is this a case of the Java spec not guaranting something but my particular implementation of java guaranteeing it for me? (java version: 1.5.0 on Ubuntu) Or have I misread something in the book? Code: (I expect an exception but it is never thrown) public class Threads { private Widgit w; public static void main(String[] s) throws Exception { while(true){ Threads t = new Threads(); t.runThreads(); } } private void runThreads() throws Exception{ new Checker().start(); w = new Widgit((int)(Math.random() * 100) + 1); } private class Checker extends Thread{ private static final int LOOP_TIMES = 1000; public void run() { int count = 0; for(int i = 0; i < LOOP_TIMES; i++){ try { w.checkMe(); count++; } catch(NullPointerException npe){ //ignore } } System.out.println("checked: "+count+" times out of "+LOOP_TIMES); } } private static class Widgit{ private int n; private int n2; Widgit(int n) throws InterruptedException{ this.n = n; Thread.sleep(2); this.n2 = n; } void checkMe(){ if (n != n2) { throw new RuntimeException("World is f*cked"); } } } }

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• Python coin-toss

  - by Andy

  i am new to Python, and i can't wrap my head around this. I have following function defined: def FlipCoins(num_flips): heads_rounds_won = 0 for i in range(10000): heads = 0 tails = 0 for j in range(num_flips): dice = random.randint(0,1) if dice==1: heads += 1 else: tails += 1 if heads > tails: heads_rounds_won += 1 return heads_rounds_won Here is what it should do (but apparently doesn't): flip a coin num_flip times, count heads and tails, and see if there are more heads than tails. If yes, increment head_rounds_won by 1. Repeat 10000 times. I would assume that head_rounds_won will approximate 5000 (50%). And it does that for odd numbers as input. For example, 3, 5 or 7 will produce about 50%. However, even numbers will produce much lower results, more like 34%. Small numbers especially, with higher even numbers, like for example 800, the difference to 50% is much narrower. Why is this the case? Shouldn't any input produce about 50% heads/tails?

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• Best Practice: Protecting Personally Identifiable Data in a ASP.NET / SQL Server 2008 Environment

  - by William

  Thanks to a SQL injection vulnerability found last week, some of my recommendations are being investigated at work. We recently re-did an application which stores personally identifiable information whose disclosure could lead to identity theft. While we read some of the data on a regular basis, the restricted data we only need a couple of times a year and then only two employees need it. I've read up on SQL Server 2008's encryption function, but I'm not convinced that's the route I want to go. My problem ultimately boils down to the fact that we're either using symmetric keys or assymetric keys encrypted by a symmetric key. Thus it seems like a SQL injection attack could lead to a data leak. I realize permissions should prevent that, permissions should also prevent the leaking in the first place. It seems to me the better method would be to asymmetrically encrypt the data in the web application. Then store the private key offline and have a fat client that they can run the few times a year they need to access the restricted data so the data could be decrypted on the client. This way, if the server get compromised, we don't leak old data although depending on what they do we may leak future data. I think the big disadvantage is this would require re-writing the web application and creating a new fat application (to pull the restricted data). Due to the recent problem, I can probably get the time allocated, so now would be the proper time to make the recommendation. Do you have a better suggestion? Which method would you recommend? More importantly why?

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• iPhone and iPad : Doing a "select * from something" query in a SQLite database

  - by Abramodj

  Hi folks, i'm trying to use the SQLite data base in my iPad app, and here's my function to make a query: - (void)executeQuery:(char*)query { NSString *file = [self getWritableDBPath]; NSFileManager *fileManager = [NSFileManager defaultManager]; BOOL success = [fileManager fileExistsAtPath:file]; // If its not a local copy set it to the bundle copy if(!success) { //file = [[NSBundle mainBundle] pathForResource:DATABASE_TITLE ofType:@"db"]; [self createEditableCopyOfDatabaseIfNeeded]; } dataArray = NULL; dataArray = [NSMutableArray array]; sqlite3 *database = NULL; if (sqlite3_open([file UTF8String], &database) == SQLITE_OK) { sqlite3_exec(database, query, loadTimesCallback, dataArray, NULL); } sqlite3_close(database); [self logResults]; } if I call [self executeQuery:"select name from table1"]; everything is working fine. But if i call [self executeQuery:"select * from cars"]; the app crashes telling me that the NSMutableArray dataArray is not the right kind of variable where to set the query results. So, how can i do a "select * form table1" query, and store the results? Thanks! EDIT: Here's my loadTimesCallback method: static int loadTimesCallback(void *context, int count, char **values, char **columns) { NSMutableArray *times = (NSMutableArray *)context; for (int i=0; i < count; i++) { const char *nameCString = values[i]; [times addObject:[NSString stringWithUTF8String:nameCString]]; } return SQLITE_OK; }

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• How can I make a simple path generator?

  - by user360737

  Hi all, I have a link that I have to repeat 50 times, for each folder, and I have 15 folders.the link that I have to repeat looks like this: <a href="update/images/Cars/car (x).JPG" rel="lightbox[cars]"></a> now, the jpg files are named car 1- car 50. and I would really like to be able to generate this script so that I can input the path "update/images/Cars/" the picture title (car) and the input the number of times that I need this link, and then have it spit out something that looks like this: <a href="update/images/Cars/car (1).JPG" rel="lightbox[cars]"></a> <a href="update/images/Cars/car (2).JPG" rel="lightbox[cars]"></a> <a href="update/images/Cars/car (3).JPG" rel="lightbox[cars]"></a> <a href="update/images/Cars/car (4).JPG" rel="lightbox[cars]"></a> <a href="update/images/Cars/car (5).JPG" rel="lightbox[cars]"></a> <a href="update/images/Cars/car (6).JPG" rel="lightbox[cars]"></a> and then it keeps repeating, I'm assuming this can be done with a counter, but I'm not sure. Thanks!

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• Nested Resource testing RSpec

  - by Joseph DelCioppio

  I have two models: class Solution < ActiveRecord::Base belongs_to :owner, :class_name => "User", :foreign_key => :user_id end class User < ActiveRecord::Base has_many :solutions end with the following routing: map.resources :users, :has_many => :solutions and here is the SolutionsController: class SolutionsController < ApplicationController before_filter :load_user def index @solutions = @user.solutions end private def load_user @user = User.find(params[:user_id]) unless params[:user_id].nil? end end Can anybody help me with writing a test for the index action? So far I have tried the following but it doesn't work: describe SolutionsController do before(:each) do @user = Factory.create(:user) @solutions = 7.times{Factory.build(:solution, :owner => @user)} @user.stub!(:solutions).and_return(@solutions) end it "should find all of the solutions owned by a user" do @user.should_receive(:solutions) get :index, :user_id => @user.id end end And I get the following error: Spec::Mocks::MockExpectationError in 'SolutionsController GET index, when the user owns the software he is viewing should find all of the solutions owned by a user' #<User:0x000000041c53e0> expected :solutions with (any args) once, but received it 0 times Thanks in advance for all the help. Joe

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• What's a good way to provide additional decoration/metadata for Python function parameters?

  - by Will Dean

  We're considering using Python (IronPython, but I don't think that's relevant) to provide a sort of 'macro' support for another application, which controls a piece of equipment. We'd like to write fairly simple functions in Python, which take a few arguments - these would be things like times and temperatures and positions. Different functions would take different arguments, and the main application would contain user interface (something like a property grid) which allows the users to provide values for the Python function arguments. So, for example function1 might take a time and a temperature, and function2 might take a position and a couple of times. We'd like to be able to dynamically build the user interface from the Python code. Things which are easy to do are to find a list of functions in a module, and (using inspect.getargspec) to get a list of arguments to each function. However, just a list of argument names is not really enough - ideally we'd like to be able to include some more information about each argument - for instance, it's 'type' (high-level type - time, temperature, etc, not language-level type), and perhaps a 'friendly name' or description. So, the question is, what are good 'pythonic' ways of adding this sort of information to a function. The two possibilities I have thought of are: Use a strict naming convention for arguments, and then infer stuff about them from their names (fetched using getargspec) Invent our own docstring meta-language (could be little more than CSV) and use the docstring for our metadata. Because Python seems pretty popular for building scripting into large apps, I imagine this is a solved problem with some common conventions, but I haven't been able to find them.

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• Why is calling close() after fopen() not closing?

  - by Richard Morgan

  I ran across the following code in one of our in-house dlls and I am trying to understand the behavior it was showing: long GetFD(long* fd, const char* fileName, const char* mode) { string fileMode; if (strlen(mode) == 0 || tolower(mode[0]) == 'w' || tolower(mode[0]) == 'o') fileMode = string("w"); else if (tolower(mode[0]) == 'a') fileMode = string("a"); else if (tolower(mode[0]) == 'r') fileMode = string("r"); else return -1; FILE* ofp; ofp = fopen(fileName, fileMode.c_str()); if (! ofp) return -1; *fd = (long)_fileno(ofp); if (*fd < 0) return -1; return 0; } long CloseFD(long fd) { close((int)fd); return 0; } After repeated calling of GetFD with the appropriate CloseFD, the whole dll would no longer be able to do any file IO. I wrote a tester program and found that I could GetFD 509 times, but the 510th time would error. Using Process Explorer, the number of Handles did not increase. So it seems that the dll is reaching the limit for the number of open files; setting _setmaxstdio(2048) does increase the amount of times we can call GetFD. Obviously, the close() is working quite right. After a bit of searching, I replaced the fopen() call with: long GetFD(long* fd, const char* fileName, const char* mode) { *fd = (long)open(fileName, 2); if (*fd < 0) return -1; return 0; } Now, repeatedly calling GetFD/CloseFD works. What is going on here?

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• Android opengl releasing textures

  - by user1642418

  I have a bit of a problem. I am developing a game for android + engine and I got stuck. I am getting OpenGL out of memory error and either app crashes or phone hangs after loading a scene multiple times. For example: app launches, shows main menu, 1st level/scene is loaded. Then I go back to main menu, and repeat. It doesnt matter which scene I load, after 4-6 times the error occurs. Some background: Each time when scene is loaded all the resources are released and upon first frame render - needed stuff gets loaded. The performance is more or less ok. Note that I am calling glDeleteTexture method, but I think its not doing its job and releasing memory. Thing is that -when I minimize and open it again - problem doesn't occur, but almost the same things are executed. Problem doesn't occur. This way android releases memory. How do I release/get rid of unused textures properly? This happens on HTC Desire HD ( ice cream sandwich 4.0.4) . Other games works fine, so I bet this is not the problem in ROM.

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• Understanding REST: is GET fundamentally incompatible with any "number of views" counter?

  - by cocotwo

  I'm trying to understand REST. Under REST a GET must not trigger something transactional on the server (this is a definition everybody agrees upon, it is fundamental to REST). So imagine you've got a website like stackoverflow.com (I say like so if I got the underlying details of SO wrong it doesn't change anything to my question), where everytime someone reads a question, using a GET, there's also some display showing "This question has been read 256 times". Now someone else reads that question. The counter now is at 257. The GET is transactional because the number of views got incremented and is now incremented again. The "number of views" is incremented in the DB, there's no arguing about that (for example on SO the number of time any question has been viewed is always displayed). So, is a REST GET fundamentally incompatible with any kind of "number of views" like functionality in a website? So should it want to be "RESTFUL", should the SO main page either stop display plain HTML links that are accessed using GETs or stop displaying the "this question has been viewed x times"? Because incrementing a counter in a DB is transactional and hence "unrestful"? EDIT just so that people Googling this can get some pointers: From http://www.xfront.com/REST-Web-Services.html : 4. All resources accessible via HTTP GET should be side-effect free. That is, the request should just return a representation of the resource. Invoking the resource should not result in modifying the resource. Now to me if the representation contains the "number of views", it is part of the resource [and in SO the "number of views" a question has is a very important information] and accessing it definitely modifies the resource. This is in sharp contrast with, say, a true RESTFUL HTTP GET like the one you can make on an Amazon S3 resource, where your GET is guaranteed not to modify the resource you get back. But then I'm still very confused.

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• Using JMX classes to notify on events over time

  - by Cincinnati Joe

  I've been looking at JMX for monitoring application and system metrics (partially because MBeans can accessed by various tools such as JConsole). It would seem like the classes included with JMX would be useful for things like notification when metrics have exceeded thresholds. But I'm not sure they fit with the way I want to measure these over a specified time period. For example, let's say I want to notify an admin when the average CPU load is over 95% for more than 5 minutes. Is that something can be done with a GaugeMonitor? From the docs, it doesn't seem quite suited for this, and I'm wondering if instead I should write my own MBean with the necessary logic. A more relevant example is when the login times for users exceed 10s over a period of 5 mins. Slightly different would be the last 20 logins took more than 10s on average. Another case would be when a process crashes 4+ times in an hour. Or the request queue exceeds 15 for 5 mins. Are the JMX Monitor classes useful for this kind of thing?

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• How to make write operation idempotent?

  - by Morgan Cheng

  I'm reading article about recently release Gizzard sharding framework by twitter(http://engineering.twitter.com/2010/04/introducing-gizzard-framework-for.html). It mentions that all write operations must be idempotent to make sure high reliability. According to wikipedia, "Idempotent operations are operations that can be applied multiple times without changing the result." But, IMHO, in Gazzard case, idempotent write operation should be operations that sequence doesn't matter. Now, my question is: How to make write operation idempotent? The only thing I can image is to have a version number attached to each write. For example, in blog system. Each blog must have a $blog_id and $content. In application level, we always write a blog content like this write($blog_id, $content, $version). The $version is determined to be unique in application level. So, if application first try to set one blog to "Hello world" and second want it to be "Goodbye", the write is idempotent. We have such two write operations: write($blog_id, "Hello world", 1); write($blog_id, "Goodbye", 2); These two operations are supposed to changed two different records in DB. So, no matter how many times and what sequence these two operations executed, the results are same. This is just my understanding. Please correct me if I'm wrong.

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• Problems with Threading in Python 2.5, KeyError: 51, Help debugging?

  - by vignesh-k

  I have a python script which runs a particular script large number of times (for monte carlo purpose) and the way I have scripted it is that, I queue up the script the desired number of times it should be run then I spawn threads and each thread runs the script once and again when its done. Once the script in a particular thread is finished, the output is written to a file by accessing a lock (so my guess was that only one thread accesses the lock at a given time). Once the lock is released by one thread, the next thread accesses it and adds its output to the previously written file and rewrites it. I am not facing a problem when the number of iterations is small like 10 or 20 but when its large like 50 or 150, python returns a KeyError: 51 telling me element doesn't exist and the error it points out to is within the lock which puzzles me since only one thread should access the lock at once and I do not expect an error. This is the class I use: class errorclass(threading.Thread): def __init__(self, queue): self.__queue=queue threading.Thread.__init__(self) def run(self): while 1: item = self.__queue.get() if item is None: break result = myfunction() lock = threading.RLock() lock.acquire() ADD entries from current thread to entries in file and REWRITE FILE lock.release() queue = Queue.Queue() for i in range(threads): errorclass(queue).start() for i in range(desired iterations): queue.put(i) for i in range(threads): queue.put(None) Python returns with KeyError: 51 for large number of desired iterations during the adding/write file operation after lock access, I am wondering if this is the correct way to use the lock since every thread has a lock operation rather than every thread accessing a shared lock? What would be the way to rectify this?

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• Survey statistic diagram ideas

  - by Nort

  Hey everyone, I've got some homework tasks in topic surveys and diagrams. The first task is to normalize the input of a survey, because the structure of the data is changing from time-to-time. So there are three types of surveys: static fields, where text is stored dynamic ones, where the user can select one option and multiselect fields, where the user can select multiple options So I'm not really a statistics guy, so I have really no idea what I can do with that incomming data. So the data I have is stored in an orbital XML file from there I can easily get how man times a survey was filled, and how many times a field was filled, so I can (for eg on a pie chart show the relation of filled or not filled). The second idea is to show the relation between the content of a multi option element using a bar chart or so. In case of the multi option elements I've got the idea to show data in implication of one option. But the question is, what could be shown? The other problem are the static elements (text fields and so). What data could be represented from a single field? The data in the XML field is collected from 2001 to 2005 So maybe I can work with the dates of the surveys, but as I said, i don't really know how to process the data, to collect as much data as possible.

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• How to get Amazon s3 PHP SDK working?

  - by JakeRow123

  I'm trying to set up s3 for the first time and trying to run the sample file that comes with the PHP sdk that creates a bucket and attempts to upload some demo files to it. But this is the error I am getting: The difference between the request time and the current time is too large. I read on another question on SO that this is because Amazon determines a valid request by comparing the times between the server and the client, that the 2 must be within a 15 min span of one another. Now here is the problem. My laptop's time is 12:30AM June 8, 2012 at the moment. On my server I created a file called servertime.php and placed this code in that file: <?php print strftime('%c'); ?> and the output is: Fri Jun 8 00:31:22 2012 It looks like the day is correct but I don't know what to make of 00:31:22. In any case, how is it possible to always make sure the time between the client and server is within a 15 minute window of one another. What if I have a user in China who wishes to upload a file on my site which uses s3 for the cdn. Then the time difference would be over a day. How can I make sure all my user's times are within 15 minutes of my server time? What if the user is in the U.S. but the time on their machine is misconfigured. Basically how to get s3 bucket creation and upload to work?

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• How to keep track of call statistics? C++

  - by tf.rz

  I'm working on a project that delivers statistics to the user. I created a class called Dog, And it has several functions. Speak, woof, run, fetch, etc. I want to have a function that spits out how many times each function has been called. I'm also interested in the constructor calls and destructor calls as well. I have a header file which defines all the functions, then a separate .cc file that implements them. My question is, is there a way to keep track of how many times each function is called? I have a function called print that will fetch the "statistics" and then output them to standard output. I was considering using static integers as part of the class itself, declaring several integers to keep track of those things. I know the compiler will create a copy of the integer and initialize it to a minimum value, and then I'll increment the integers in the .cc functions. I also thought about having static integers as a global variable in the .cc. Which way is easier? Or is there a better way to do this? Any help is greatly appreciated!

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• How does SVN store commit time

  - by Salman

  I am working on a project that involves extracting details from a SVN server using SVNKit. My project is already complete and has been working we for a while now. During the testing, I noticed something rather very strange. the Commit Times my extract data seems is alway different from whats there in SVN Logs. I couldnt find any code in my project that could be inducing this difference but now I am looking as to how SVN server stores the Commit time in itself. As we have developer working from different part of the world thus resulting in different timezones, I was thinking that SVN might be storing time after converting them to GMT or timezone of the system on which SVN server is running. But that does not seem to be happening. Instead the times are stored as per the time when the commit was done and in that local timezone itself. I have been unable to find any substantial document on internet to support my theory so far. Can anybody in brief explain as how SVN store the Commit Time for each change? Documentaion links referring to this will be of great help.

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• Reduce durability in MySQL for performance

  - by Paul Prescod

  My site occasionally has fairly predictable bursts of traffic that increase the throughput by 100 times more than normal. For example, we are going to be featured on a television show, and I expect in the hour after the show, I'll get more than 100 times more traffic than normal. My understanding is that MySQL (InnoDB) generally keeps my data in a bunch of different places: RAM Buffers commitlog binary log actual tables All of the above places on my DB slave This is too much "durability" given that I'm on an EC2 node and most of the stuff goes across the same network pipe (file systems are network attached). Plus the drives are just slow. The data is not high value and I'd rather take a small chance of a few minutes of data loss rather than have a high probability of an outage when the crowd arrives. During these traffic bursts I would like to do all of that I/O only if I can afford it. I'd like to just keep as much in RAM as possible (I have a fair chunk of RAM compared to the data size that would be touched over an hour). If buffers get scarce, or the I/O channel is not too overloaded, then sure, I'd like things to go to the commitlog or binary log to be sent to the slave. If, and only if, the I/O channel is not overloaded, I'd like to write back to the actual tables. In other words, I'd like MySQL/InnoDB to use a "write back" cache algorithm rather than a "write through" cache algorithm. Can I convince it to do that? If this is not possible, I am interested in general MySQL write-performance optimization tips. Most of the docs are about optimizing read performance, but when I get a crowd of users, I am creating accounts for all of them, so that's a write-heavy workload.

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• MySQL - What is wrong with this query or my database? Terrible performance.

  - by Moss

  SELECT * from `employees` a LEFT JOIN (SELECT phone1 p1, count(*) c, FROM `employees` GROUP BY phone1) b ON a.phone1 = b.p1; I'm not sure if it is this query in particular that has the problem. I have been getting terrible performance in general with this database. The table in question has 120,000 rows. I have tried this particular query remotely and locally with the MyISAM and InnoDB engines, with different types of joins, and with and without an index on phone1. I can get this to complete in about 4 minutes on a 10,000 row table successfully but performance drops exponentially with larger tables. Remotely it will lose connection to the server and locally it brings my system to its knees and seems to go on forever. This query is only a smaller step I was trying to do when a larger query couldn't complete. Maybe I should explain the whole scenario. I have one big flat ugly table that lists a bunch of people and their contact info and the info of the companies they work for. I'm trying to normalize the database and intelligently determine which phone numbers apply to individual people and which apply to an office location. My reasoning is that if a phone number occurs multiple times and the number of occurrence equals the number of times that the street address it is attached to occurs then it must be an office number. So the first step is to count each phone number grouping by phone number. Normally if you just use COUNT()...GROUP BY it will only list the first record it finds in that group so I figured I have to join the full table to the count table where the phone number matches. This does work but as I said I can't successfully complete it on any table much larger than 10,000 rows. This seems pathetic and this doesn't seem like a crazy query to do. Is there a better way to achieve what I want or do I have to break my large table into 12 pieces or is there something wrong with the table or db?

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• populate drop-down values dynamically using Ajax

  - by abhishek

  Hi, I have 3 drop-downs. 1st drop-down contains some values when the page loads. I need to populate 2 nd drop-down based on the value selected in 1st dropdown. Similarly, I need to populate 3 nd drop-down based on the value selected in 1st and 2nd dropdown. Initially I tried like this. <h:selectOneMenu value="#{stu.country}" > <f:selectItems value="#{bean.allCountries}" /> <a4j:support event="onchange" action="#{bean.retrieveStates(stu.country)}" reRender="states_dropDown"></a4j:support> </h:selectOneMenu> //ly, for 2nd drop-down <h:selectOneMenu id="states_dropDown" value="#{stu.state}" > <f:selectItems value="#{bean.allStates}" /> <a4j:support event="onchange" action="#{bean.retrieveCities(stu.country,stu.state)}" reRender="City_dropDown"></a4j:support> </h:selectOneMenu> Some times this code works fine. But some times it doesn't invoke managed bean method. Can you please help??

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• javascript array/object issue

  - by FlyingCat

  I am trying to push elements to an array. for (a=0; a < test.length; a++){ if(this.testnumber != test[a].number){ //it will only loop 8 times under conditional statement group = { title: test.Title , ID: test.ID, contents: [] }; this.company.push(group); this.testnumber = test.number[a]; } //outside of if conditional statement.. it will loop 15 times //i want every test[a].conetents get pushed to group.contents array. //this.company is the final variable I need for this function... group.contents.push(test[a].contents); } However, when I do console.log(this.company); I see 8 elmements with only 1 element in each group.contents array The ideal situation is to have 8 elements with 2 to 3 elements in the group.contents array I hope I explain my situation well. Any idea how to solve my issue? Thanks a lot!

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