Search Results

Search found 24132 results on 966 pages for 'non clustered index'.

Page 316/966 | < Previous Page | 312 313 314 315 316 317 318 319 320 321 322 323  | Next Page >

  • How can CopyOnWriteArrayList be thread-safe?

    - by Shooshpanchick
    I've taken a look into OpenJDK's sources of CopyOnWriteArrayList and it seems that all write operations are protected by the same lock and read operations are not protected at all. As I understand, under JMM all accesses to a variable (both read and write) should be protected by lock or reordering effects may occur. For example, set(int, E) method contains these lines (under lock): /* 1 */ int len = elements.length; /* 2 */ Object[] newElements = Arrays.copyOf(elements, len); /* 3 */ newElements[index] = element; /* 4 */ setArray(newElements); The get(int) method, on the other hand, only does return get(getArray(), index);. In my understanding of JMM, this means that get may observe the array in an inconsistent state if statements 1-4 are reordered like 1-2(new)-4-2(copyOf)-3. Do I understand JMM incorrectly or is there any other explanations on why CopyOnWriteArrayList is thread-safe?

    Read the article

  • Why does std::map operator[] create an object if the key doesn't exist?

    - by n1ck
    Hi, I'm pretty sure I already saw this question somewhere (comp.lang.c++? Google doesn't seem to find it there either) but a quick search here doesn't seem to find it so here it is: Why does the std::map operator[] create an object if the key doesn't exist? I don't know but for me this seems counter-intuitive if you compare to most other operator[] (like std::vector) where if you use it you must be sure that the index exists. I'm wondering what's the rationale for implementing this behavior in std::map. Like I said wouldn't it be more intuitive to act more like an index in a vector and crash (well undefined behavior I guess) when accessed with an invalid key? Refining my question after seeing the answers: Ok so far I got a lot of answers saying basically it's cheap so why not or things similar. I totally agree with that but why not use a dedicated function for that (I think one of the comment said that in java there is no operator[] and the function is called put)? My point is why doesn't map operator[] work like a vector? If I use operator[] on an out of range index on a vector I wouldn't like it to insert an element even if it was cheap because that probably mean an error in my code. My point is why isn't it the same thing with map. I mean, for me, using operator[] on a map would mean: i know this key already exist (for whatever reason, i just inserted it, I have redundancy somewhere, whatever). I think it would be more intuitive that way. That said what are the advantage of doing the current behavior with operator[] (and only for that, I agree that a function with the current behavior should be there, just not operator[])? Maybe it give clearer code that way? I don't know. Another answer was that it already existed that way so why not keep it but then, probably when they (the ones before stl) choose to implement it that way they found it provided an advantage or something? So my question is basically: why choose to implement it that way, meaning a somewhat lack of consistency with other operator[]. What benefit do it give? Thanks

    Read the article

  • Filtering out unique rows in MySQL

    - by jpatokal
    So I've got a large amount of SQL data that looks basically like this: user | src | dst 1 | 1 | 1 1 | 1 | 1 1 | 1 | 2 1 | 1 | 2 2 | 1 | 1 2 | 1 | 3 I want to filter out pairs of (src,dst) that are unique to one user (even if that user has duplicates), leaving behind only those pairs belonging to more than one user: user | src | dst 1 | 1 | 1 1 | 1 | 1 2 | 1 | 1 In other words, pair (1,2) is unique to user 1 and pair (1,3) to user 2, so they're dropped, leaving behind only all instances of pair (1,1). Any ideas? The answers to the question below can find the non-unique pairs, but my SQL-fu doesn't suffice to handle the complication of requiring that they belong to multiple users as well. [SQL question] How to select non "unique" rows

    Read the article

  • Problems getting PowerPoint Combobox to list items correctly

    - by mike toyn
    I am creating a PowerPoint in which I want users to be able to select an item from a list in a combo box. Nothing needs to happen after this, it is just to provide a record, on screen, of their choice. My problem is that I seem to either be able to populate the combo box and users can select an item but the list gets longer each time the combobox is clicked on (i.e each time it is clicked on the list gets duplicated). Or alternatively, I can clear the combo box, then populate it but in this scenario, the users choice also seems to get cleared. VBA example 1: Private Sub ComboBox1_DropButtonClick() With ComboBox1 .AddItem " ", 0 .AddItem "speed", 1 .AddItem "provisionality", 2 .AddItem "automation", 3 .AddItem "replication", 4 .AddItem "communicability", 5 .AddItem "multi-modality", 6 .AddItem "non-linearity", 7 .AddItem "capacity", 8 .AddItem "interactivity", 9 End With End Sub VBA example 2: Private Sub ComboBox1_DropButtonClick() ComboBox1.Clear With ComboBox1 .AddItem " ", 0 .AddItem "speed", 1 .AddItem "provisionality", 2 .AddItem "automation", 3 .AddItem "replication", 4 .AddItem "communicability", 5 .AddItem "multi-modality", 6 .AddItem "non-linearity", 7 .AddItem "capacity", 8 .AddItem "interactivity", 9 End With End Sub Can anyone help?

    Read the article

  • Implementing a runtime Look Up Table in C#

    - by Yarok
    Hey all, I'm currently working on a robot interface GUI, using C#. The robot has two sensors, and two powered wheels. I need to let the user the option to load a Look Up Table (LUT) during runtime, one for each sensor, that will tell the robot what to do according to the sensor's reading. I think the best way to do it is using a .csv file, formatted like so: index , right wheel order, left wheel order the index is an int between 0-1023 and is actually the sensor's reading. the orders for the right and left wheel are integers, between -500 - 500. Example - left sensor's readings: 1,10,20 meaning: sensor reads 1 -- left wheel 10 rpm right wheel 20 rpm So my question is this: what is the best way to implement it? using a dataset?(if so, how?) using an array? (if so, how do I load it during runtime?) Any help would be much appreciated, Yarok

    Read the article

  • Objective-C: how to allocate array of GLuint

    - by sashaeve
    I have an array of GLuint with fixed size: GLuint textures[10]; Now I need to set a size of array dynamically. I wrote something like this: *.h: GLuint *textures; *.m: textures = malloc(N * sizeof(GLuint)); where N - needed size. Then it used like this: glGenTextures(N, &textures[0]); // load texture from image -(GLuint)getTexture:(int)index{ return textures[index]; } I used the answer from here, but program fell in runtime. How to fix this? Program is written on Objective-C and uses OpenGL ES.

    Read the article

  • Reducing number of include files to reduce server load/speed up site?

    - by rein
    You can reduce the number of HTTP requests to speed up your site, such as css sprite images. I'm wondering does reducing the number of php includes/requires also speed up your site or reduce server load? For example, I have a index.php with <?php include './file.php'; ?> If instead I copy and paste the code from file.php and just put it into index.php, thus removing the include code, would it reduce the server load? This might make things less organized, but if it does reduce server load I might need to do that. For a small to medium sized site, I assume there might not be a difference, but how about for high traffic sites? Thanks in advance.

    Read the article

  • Why is Postgres doing a Hash in this query?

    - by Claudiu
    I have two tables: A and P. I want to get information out of all rows in A whose id is in a temporary table I created, tmp_ids. However, there is additional information about A in the P table, foo, and I want to get this info as well. I have the following query: SELECT A.H_id AS hid, A.id AS aid, P.foo, A.pos, A.size FROM tmp_ids, P, A WHERE tmp_ids.id = A.H_id AND P.id = A.P_id I noticed it going slowly, and when I asked Postgres to explain, I noticed that it combines tmp_ids with an index on A I created for H_id with a nested loop. However, it hashes all of P before doing a Hash join with the result of the first merge. P is quite large and I think this is what's taking all the time. Why would it create a hash there? P.id is P's primary key, and A.P_id has an index of its own.

    Read the article

  • getting error 500 with .htaccess when pointing an existing file / folder (mod_rewrite)

    - by Leto
    i made a simple .htaccess file to expose the problem. I want that all request made to the folder redirect to a subfolder file "app/index.php" RewriteEngine On RewriteRule (.*) app/index.php [QSA] And this works fine on with the basic url of my hoster (like http//myname.hosting.com/htaccessFolder The problem is that i have a domain pointing on this folder, and when accessed to it, server return Internal Server Error 500. If i do this : RewriteEngine On RewriteRule (.*) somefile.php [QSA] Redirection works only when file does not exists (404 not found error occured). when the file exists i get a 500 error too. I've asked the hosting support without success for the moment..

    Read the article

  • Generate matrix with value flags

    - by pagid
    I do have a solution for the following problem but it's quite ugly and it can most likely be done in a much shorter way. Would be great to get your help. My input looks like this: C1 C2 A B B D D C A D and my output should look like this: A B C D 1 1 0 0 0 1 0 1 0 0 1 1 1 0 0 1 My current solution is: index <- unique(unlist(input[,1:2])) output <- matrix(0,nrows=dim(input),ncols=length(index)) for(i in 1:dim(input)) { output[i, input[i,]$C1] <- 1 output[i, input[i,]$C2] <- 1 } Of course 4-5 lines is actually fine - but even as an R beginner this doesn't feel right to use a for loop. Besides that my actual data has much more than two columns, therefore this doesn't look nice in the end. How would I do that in a smarter way? Cheers

    Read the article

  • Tips about a good class-structure for website? (php)

    - by Martti Laine
    Hello I'm creating a kind of massive network for users to register and login. I want to try using classes, but I've never used them (expect some mysql-wrappers etc). Could you provide some tips and sample-structure for my project? The idea is to simply have a index.php, which prints the whole page and does all the action. Index.php calls functions from classes inside other files. I need: user-class for checking if logged in and retrieving user-info different kind of "page"-classes for functions needed in those pages I'm not asking for full code, but just a start. I don't know, how to use public functions or anything like that. How to wrap these classes to work together? So no functions, just the structure! Martti Laine

    Read the article

  • If I don't odr-use a variable, can I have multiple definitions of it across translation units?

    - by sftrabbit
    The standard seems to imply that there is no restriction on the number of definitions of a variable if it is not odr-used (§3.2/3): Every program shall contain exactly one definition of every non-inline function or variable that is odr-used in that program; no diagnostic required. It does say that any variable can't be defined multiple times within a translation unit (§3.2/1): No translation unit shall contain more than one definition of any variable, function, class type, enumeration type, or template. But I can't find a restriction for non-odr-used variables across the entire program. So why can't I compile something like the following: // other.cpp int x; // main.cpp int x; int main() {} Compiling and linking these files with g++ 4.6.3, I get a linker error for multiple definition of 'x'. To be honest, I expect this, but since x is not odr-used anywhere (as far as I can tell), I can't see how the standard restricts this. Or is it undefined behaviour?

    Read the article

  • rails: undefined method and form_tags

    - by SuperString
    I have this in courses.html.erb under app/views/students <% if @student.courses.count < Course.count then%> <% form_tag(course_add_student_path(@student)) do%> <%= select_tag(:course, options_from_collection_for_select(@student.unenrolled_courses, :id, :name))%> <%= submit_tag 'Enroll'%> <%end%> <%else%> <p><%=h @student.name%> is enrolled in every course. </p> <%end%> I have this in my students_controller.rb under app/controllers: def course_add @student = Student.find(params[:id]) @course = Course.find(params[:course]) unless @student.enrolled_in?(@course) @student.coursess << @course flash[:notice] = 'course added' else flash[:error] = 'course already enrolled' end redirect_to :action => courses, :id => @student end And in my routes.rb, I have: resources :students, :has_many => [:awards], :member => {:courses => :get, :course_add => :post, :course_remove => :post} However, I am getting this error: undefined method `course_add_student_path' for #<#<Class:0x105321d78>:0x1053200e0> What am I missing here? Rake routes output: students GET /students(.:format) {:action=>"index", :controller=>"students"} POST /students(.:format) {:action=>"create", :controller=>"students"} new_student GET /students/new(.:format) {:action=>"new", :controller=>"students"} edit_student GET /students/:id/edit(.:format) {:action=>"edit", :controller=>"students"} student GET /students/:id(.:format) {:action=>"show", :controller=>"students"} PUT /students/:id(.:format) {:action=>"update", :controller=>"students"} DELETE /students/:id(.:format) {:action=>"destroy", :controller=>"students"} courses GET /courses(.:format) {:action=>"index", :controller=>"courses"} POST /courses(.:format) {:action=>"create", :controller=>"courses"} new_course GET /courses/new(.:format) {:action=>"new", :controller=>"courses"} edit_course GET /courses/:id/edit(.:format) {:action=>"edit", :controller=>"courses"} course GET /courses/:id(.:format) {:action=>"show", :controller=>"courses"} PUT /courses/:id(.:format) {:action=>"update", :controller=>"courses"} DELETE /courses/:id(.:format) {:action=>"destroy", :controller=>"courses"} student_awards GET /students/:student_id/awards(.:format) {:action=>"index", :controller=>"awards"} POST /students/:student_id/awards(.:format) {:action=>"create", :controller=>"awards"} new_student_award GET /students/:student_id/awards/new(.:format) {:action=>"new", :controller=>"awards"} edit_student_award GET /students/:student_id/awards/:id/edit(.:format) {:action=>"edit", :controller=>"awards"} student_award GET /students/:student_id/awards/:id(.:format) {:action=>"show", :controller=>"awards"} PUT /students/:student_id/awards/:id(.:format) {:action=>"update", :controller=>"awards"} DELETE /students/:student_id/awards/:id(.:format) {:action=>"destroy", :controller=>"awards"} courses_student GET /students/:id/courses(.:format) {:action=>"courses", :controller=>"students"} GET /students(.:format) {:action=>"index", :controller=>"students"} POST /students(.:format) {:action=>"create", :controller=>"students"} GET /students/new(.:format) {:action=>"new", :controller=>"students"} GET /students/:id/edit(.:format) {:action=>"edit", :controller=>"students"} GET /students/:id(.:format) {:action=>"show", :controller=>"students"} PUT /students/:id(.:format) {:action=>"update", :controller=>"students"} DELETE /students/:id(.:format) {:action=>"destroy", :controller=>"students"}

    Read the article

  • Spring 3.0 MVC mvc:view-controller tag

    - by gouki
    Here's a snippet of my mvc-config.xml <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver"> <property name="prefix" value="/WEB-INF/views/"/> <property name="suffix" value=".jsp"/> </bean> <mvc:view-controller path="/index" view-name="welcome"/> <mvc:view-controller path="/static/login" view-name="/static/login"/> <mvc:view-controller path="/login" view-name="/static/login"/> I have the welcome.jsp on /WEB-INF/view/ directory and login.jsp on /WEB-INF/view/static/. This work for '/index' and '/login' paths. But I'm getting 404 response for '/static/login' when invoked from the browser. I'm expecting that '/static/login/' and '/login' should behave the same. What could be wrong here? Would appreciate any help. Thanks!

    Read the article

  • Nested pound sign problem

    - by Ray Buechler
    I'm having an issue when I try to nest pound signs in my ColdFusion code. I keep getting the following error message: Invalid CFML construct found on line 57 at column 26. ColdFusion was looking at the following text: # Here is the code: <cfloop index="i" from="1" to="12"> <cfset needRecord.setNeed#i#(#form["need#i#"]#) /> </cfloop> If I run the loop outside the cfset tag like this: <cfloop index="i" from="1" to="12"> needRecord.setNeed#i#(#form["need#i#"]#) </cfloop> The code runs and generates what I would like to generate within the cfset tag. Any idea what I'm doing wrong? Any help would be greatly appreciated.

    Read the article

  • Firefox can not layout nested tables properly?

    - by ooplidi
    I want to implement a collapsible menu. I plan to use table component to simulate a menu, and nest a sub table into a table cell to simulate a sub menu. Below is my code, it works as expected in IE, Chrome and Safari, but it doesn't work well in Firefox: <html> <body> <div id="menu" style="position:absolute; left:150px; top:100px; z-index:1"> <table width="200px" height="90" border=1 cellpadding="0" cellspacing="0"> <tr> <td colspan=2>Money</td> </tr> <tr> <td colspan=2>Tool</td> </tr> <tr> <td>Food <table style="position:absolute; left:200px; top:60px; z-index:1" width="200px" height="60px" border="1" cellpadding="0" cellspacing="0"> <tr> <td>Cookie</td> </tr> <tr> <td>Fruit <table style="position:absolute; left:200px; top:30px; z-index:1" width="200px" height="60px" border="1" cellpadding="0" cellspacing="0"> <tr> <td>Apple</td> </tr> <tr> <td>Banana</td> </tr> </table> </td> </tr> </table> </td> </tr> </table> </div> </body> </html> It seems that Firefox think the "left" and "top" attribute for the level 3 menu is relative to the level 1 menu, so it layout the level 3 menu incorrectly. Other browsers will calculate the offset base on the level 2 menu, that works as expected. Is it a bug in Firefox? If so how can I work around it? I want my code to have the same behavior in all major browsers.

    Read the article

  • How to avoid becoming a programmer while still beign closely involved with computer science/Industry

    - by WeShallOvercome
    I am studying computer science (A masters at an Ivy league), however most of the jobs i find involve way too much of programming. And frankly programming is not an issue, however programming without a meaning (read financial institution (non trading), other non mainstream jobs) bore me to death! I dont want to end up becoming a .NET,C#, Java kind of programmer. Can someone tell where i should look for jobs if i wish to do some real computer science work such as Machine Learning etc. I don't mind programming but becoming a Financial Software dev at Bloomeberg or an SDET at Microsoft isn't actually one of my goals. [note: I have interviewed for intern both positions listed above, and thankfully i got an intern for a data mining position in a top 750 Alexa rank web company] Sorry if angered anyone with a subjective question

    Read the article

  • Java String replaceAll with conditions

    - by user1483570
    I am not good in regular expressions and I need help in replacing the string. String str = "Name_XYZ_"; str = "XYZ_NAME_"; So how can I replace "Name_" or "_NAME_" from above two strings with empty string? The conditions are "Name" can be in any case and it can be at index 0 or at any index but preceded by "_". So far I tried, String replacedString = str.replaceAll("(?i)Name_", ""); // This is not correct. This is not the homework. I am working on XML file that needs such kind of processing. Please help. Thank you.

    Read the article

  • Mongoose Not Creating Indexes

    - by wintzer
    I have been trying all afternoon to get my node.js application to create MongoDB indexes properly. I am using the Mongoose ODM and in my schema definition below I have the username field set to a unique index. The collection and document all get created properly, it's just the indexes that aren't working. All the documentation says that the ensureIndex command should be run at startup to create any indexes, but none are being made. I'm using MongoLab for hosting if that matters. I have also repeatedly dropped the collection. Please tell me what I'm doing wrong. var schemaUser = new mongoose.Schema({ username: {type: String, index: { unique: true }, required: true}, hash: String, created: {type: Date, default: Date.now} }, { collection:'Users' }); var User = mongoose.model('Users', schemaUser); var newUser = new Users({username:'wintzer'}) newUser.save(function(err) { if (err) console.log(err); });

    Read the article

  • how to get li width + margin using jquery

    - by From.ME.to.YOU
    hello my code is something like this //css li{display:inline-block} //html #li margin and width are dynamic <ul> <li style='margin:30px;width:100px;'>Pic</li> <li style='margin:40px;width:200px;'>Pic</li> <li style='margin:10px;width:500px;'>Pic</li> <li style='margin:50px;width:300px;'>Pic</li> </ul> how to make a jquery function that will take an li index as an input and it will return the width of all li from the beginning to that index + margins ' left + right ' Examples // something like this myFunction(1); //output 440 (( 30 margin-left [0] + 30 margin-right [0] + 40 margin-left [1] + 40 margin-right [1] + 100 width [0] + 200 width [1] )) myFunction(2); //output 960 (( 30 margin-left [0] + 30 margin-right [0] + 40 margin-left [1] + 40 margin-right [1] + 10 margin-left [2] + 10 margin-right [2] + 100 width [0] + 200 width [1] + 500 width [2] ))

    Read the article

  • Optional URL fragment in Codeigniter?

    - by DA
    This is maybe a simple syntax question or possibly a best-practices question in terms of codeigniter. I should start by saying I'm not a PHP or Codeigniter person so trying to get up to speed on helping on a project. I've found the CI documentation fairly good. The one question I can't find an answer to is how to make part of a URL optional. An example the CI documentation uses is this: example.com/index.php/products/shoes/sandals/123 and then the function used to parse the URI: function shoes($sandals, $id) For my example, I'd like to be able to modify the URL as such: example.com/index.php/products/shoes/all So, if no ID is passed, it's just ignored. Can that be done? Should that be done? A second question unrelated to my problem but pertaining to the example above, why would the variable $sandals be used as in the example, the value is 'sandals'? Shouldn't that variable be something like $shoetype?

    Read the article

  • how to optimize sql server table for faster response?

    - by Thomas
    i found a in a table there are 50 thousands records and it takes one minute when we fetch data from sql server table just by issuing a sql. there are one primary key that means a already a cluster index is there. i just do not understand why it takes one minute. beside index what are the ways out there to optimize a table to get the data faster. in this situation what i need to do for faster response. also tell me how we can write always a optimize sql. please tell me all the steps in detail for optimization. thanks.

    Read the article

  • crash in the handler that moves up a treenode in a treeview c#

    - by voodoomsr
    i have a event handler that moves the selected treenode up. I don't know why is crash in the line with comented. treeviewdocxml is a treeview object, from System.Windows.Forms treeViewDocXml.BeginUpdate(); TreeNode sourceNode = treeViewDocXml.SelectedNode; if (sourceNode.Parent == null) { return; } if (sourceNode.Index > 0) { sourceNode.Parent.Nodes.Remove(sourceNode); sourceNode.Parent.Nodes.Insert(sourceNode.Index - 1, sourceNode); //HERE CRASH } treeViewDocXml.EndUpdate();

    Read the article

< Previous Page | 312 313 314 315 316 317 318 319 320 321 322 323  | Next Page >