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  • mysql index optimization for a table with multiple indexes that index some of the same columns

    - by Sean
    I have a table that stores some basic data about visitor sessions on third party web sites. This is its structure: id, site_id, unixtime, unixtime_last, ip_address, uid There are four indexes: id, site_id/unixtime, site_id/ip_address, and site_id/uid There are many different types of ways that we query this table, and all of them are specific to the site_id. The index with unixtime is used to display the list of visitors for a given date or time range. The other two are used to find all visits from an IP address or a "uid" (a unique cookie value created for each visitor), as well as determining if this is a new visitor or a returning visitor. Obviously storing site_id inside 3 indexes is inefficient for both write speed and storage, but I see no way around it, since I need to be able to quickly query this data for a given specific site_id. Any ideas on making this more efficient? I don't really understand B-trees besides some very basic stuff, but it's more efficient to have the left-most column of an index be the one with the least variance - correct? Because I considered having the site_id being the second column of the index for both ip_address and uid but I think that would make the index less efficient since the IP and UID are going to vary more than the site ID will, because we only have about 8000 unique sites per database server, but millions of unique visitors across all ~8000 sites on a daily basis. I've also considered removing site_id from the IP and UID indexes completely, since the chances of the same visitor going to multiple sites that share the same database server are quite small, but in cases where this does happen, I fear it could be quite slow to determine if this is a new visitor to this site_id or not. The query would be something like: select id from sessions where uid = 'value' and site_id = 123 limit 1 ... so if this visitor had visited this site before, it would only need to find one row with this site_id before it stopped. This wouldn't be super fast necessarily, but acceptably fast. But say we have a site that gets 500,000 visitors a day, and a particular visitor loves this site and goes there 10 times a day. Now they happen to hit another site on the same database server for the first time. The above query could take quite a long time to search through all of the potentially thousands of rows for this UID, scattered all over the disk, since it wouldn't be finding one for this site ID. Any insight on making this as efficient as possible would be appreciated :) Update - this is a MyISAM table with MySQL 5.0. My concerns are both with performance as well as storage space. This table is both read and write heavy. If I had to choose between performance and storage, my biggest concern is performance - but both are important. We use memcached heavily in all areas of our service, but that's not an excuse to not care about the database design. I want the database to be as efficient as possible.

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  • Nexus: removing repository

    - by David
    Hi, I accidently removed a hosted snapshot repository from Nexus containing a few artifacts needed by other developers on my team. Fine, I'll be able to recreate it fairly easy, but when I tried to add the repository again with the same name as the one I removed, the "Upload Artifact" tab did not show. I tried to clean the cache and reindex the public and public snapshot repos, but that didn't help. I also tried setting an alternative storage path by entering an alternative path on "Override Local Storage Location", same result. Will I have to create a brand new repository with a different name and change all repository reference in my projects? Thanks, David

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  • What's the best way to authorize a USB Key

    - by ScottCate
    We have an auto update for our software that is installed via USB key (with the auto run). If I wanted to ensure that only authorized USB Keys were used, what's the best way? Our installer is already signed, and it won't run otherwise. But I'm more wanting to inspect the USB Key for a signed installer, and if it's not there, just ignore, or even "Eject" the USB device. And I should be able to tell the difference (in code) between a usb storage device, and say a camera, or keyboard. I'm only wanting to disable non-authorized storage devices. Thank you for your ideas.

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  • jQuery toggle fucntion not working as expected

    - by Bunny Rabbit
    <!DOCTYPE html> <html lang="en"> <head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8"> <script src="http://ajax.googleapis.com/ajax/libs/jquery/1.3/jquery.min.js" type="text/javascript"></script> <script type="text/javascript"> $(function(){ $('div#menu div') .bind('mouseover',function(event){ popHelp(this); }) .bind('mouseout',function(event){ clearHelp(); }) .toggle( function(event){$('#menu div a').not(this).css('opacity',1);$(event.target).css('opacity',0.4)}, function(event){$(event.target).css('opacity',1)} ) $('div.item').not('#mainPage') .hide() $('#customerManagement').click(function(event){ $('.item').hide('slow'); $('#customerManagementCon').toggle('slow'); return false; }) $('#userManagement').click(function(){ $('.item').hide('slow'); $('#userManagementCon').toggle('slow'); return false; }) $('#storageManagement').click(function(){ $('.item').hide('slow'); $('#storageManagementCon').toggle('slow'); return false; }) $('#searchManagement').click(function(){ $('.item').hide('slow'); $('#searchManagementCon').toggle('slow'); return false; }) $('#signOff').click(function(){ $('.item').hide('slow'); $('#signOffCon').toggle('slow'); return false; }) } ); function popHelp(ref){ var text; if(ref.id=="customerManagement") text="click here for customer management"; else if(ref.id=="userManagement") text="click here for user management"; else if(ref.id=="storageManagement") text="click here for storage management"; else if(ref.id=="searchManagement") text="search management"; else if(ref.id=="signOff") text="click here to sign off"; $('#helpConsole').append('<div class="help">'+text+'<div>'); } function clearHelp(){ $('#helpConsole > div').remove(); } </script> <style type="text/css" > #helpConsole { background-color:Aqua; margin-left:500px; width:300px; height:100px; outline-width:medium; } </style> </head> <body> <div id="menu"> <table border="2"> <thead> <tr> <th colspan="5">Welcome $Employee Name</th> </tr> </thead> <tbody> <tr> <td><div id="customerManagement" class="menuItem"><a>Customer Management</a></div></td> <td><div id="userManagement" class="menuItem"><a>User Management</a></div></td> <td><div id="storageManagement" class="menuItem"><a>Storage Management</a></div></td> <td><div id="searchManagement" class="menuItem"><a>Search Management</a></div></td> <td><div id="signOff" class="menuItem"><a>Sign Off</a></div></td> </tr> </tbody> </table> </div> <div id="helpConsole"><h3>help</h3></div> <div id="mainPage" class="item"><h1>Storage Service</h1></div> <div id="customerManagementCon" class="item"> <h3>Customer Management</h3> </div> <div id="userManagementCon" class="item"> <h3>User Management</h3> </div> <div id="storageManagementCon" class="item"> <h3>Storage Management</h3> </div> <div id="searchManagementCon" class="item"> <h3>Search Mangement</h3> </div> <div id="signOffCon" class="item"> <h3>Sign Off</h3> </div> <div id="menuItemCon" class="item">menuItem</div> </body> The toggle function in this code is not working as expected though it shows the #menu items when clicked it doesn't hide them always .

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  • Unpacking Argument Lists and Instantiating WTForms objects from web.py

    - by Morris Cornell-Morgan
    After a bit of searching, I've found that it's possible to instantiate a WTForms object in web.py using the following code: form = my_form(**web.input()) web.input() returns a "dictionary-like" web.storage object, but without the double asterisks WTForms will raise an exception: TypeError: formdata should be a multidict-type wrapper that supports the 'getlist' method From the Python documentation I understand that the two asterisks are used to unpack a dictionary of named arguments. That said, I'm still a bit confused about exactly what is going on. What makes the web.storage object returned by web.input() "dictionary-like" enough that it can be unpacked by ** but not "dictionary-like" enough that it can be passed as-is to the WTForms constructor? I know that this is an extremely basic question, but any advice to help a novice programmer would be greatly appreciated!

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  • Java portable media detection

    - by quosoo
    I would like to write a piece of java code that synchronizes files between local hard drive and a usb storage. I would like to have a different synchronization configuration depending on which usb storage is plugged in and I would like to have apropriate configuration to be selected automatically rather than chosen by the user. I've just read the JSR-80 and jUSB documentation as well as a bunch of articles and SO posts, but all of those are very old and it seems that since that time (around 2005) all the efforts have been abandoned especially for Windows platform, while the OS-independence is quite important to me (at least Windows and Linux need to be supported). Do I really need to use any of the USB APIs to recognize external drives that are connected to the system? I need something that is more unique than file path, drive letter or drive label... And if yes which one would you recommend (unless I missed something jUnit is actually the only for which Windows support exists).

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  • jQuery TypeError: example("input#autocomplete").autocomplete is not a function

    - by Ankush Kalia
    I have tried alot to remove this error but could not get success.When i am running this script on localhost its working fine but not working on Joomla frame work. The code is below: <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1" /> <?php $viewFields=array('c++', 'java', 'php', 'coldfusion', 'javascript', 'asp', 'ruby'); ?> <link href="http://ajax.googleapis.com/ajax/libs/jqueryui/1.8/themes/base/jquery-ui.css" rel="stylesheet" type="text/css"/> <script src="http://ajax.googleapis.com/ajax/libs/jquery/1.5/jquery.min.js"></script> <script src="http://ajax.googleapis.com/ajax/libs/jqueryui/1.8/jquery-ui.min.js"></script> <script> var example=jQuery.noConflict(); var arrayFromPHP = <?php echo json_encode($viewFields) ?>; example(document).ready(function() { example("input#autocomplete").autocomplete({ source: arrayFromPHP }); }); </script> </head> <body> <center> <p><img src="<?php echo JURI::base(); ?>images/search_1.png" border="0" alt="" /> <img src="<?php echo JURI::base(); ?>images/business_2.png" border="0" alt="" /> <img src="<?php echo JURI::base(); ?>images/review_3.png" border="0" alt="" /> </p> </center> <input id="autocomplete" /> </body> </html> Its giving me this error:- -- [08:30:24.870] Use of getAttributeNode() is deprecated. Use getAttribute() instead. @ http://50.116.97.120/~amarhost/storage/media/system/js/mootools-core.js:343 [08:30:27.853] TypeError: example("input#autocomplete").autocomplete is not a function @ http://50.116.97.120/~amarhost/storage/index.php/component/storage/?action=war&Itemid=105:210

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  • static arrays defined with unspecified size, empty brackets?

    - by ahmadabdolkader
    For the C++ code fragment below: class Foo { int a[]; // no error }; int a[]; // error: storage size of 'a' isn't known void bar() { int a[]; // error: storage size of 'a' isn't known } why isn't the member variable causing an error too? and what is the meaning of this member variable? I'm using gcc version 3.4.5 (mingw-vista special) through CodeBlocks 8.02. On Visual Studio Express 2008 - Microsoft(R) C/C++ Optimizing Compiler 15.00.30729.01 for 80x86, I got the following messages: class Foo { int a[]; // warning C4200: nonstandard extension used : zero-sized array in struct/union - Cannot generate copy-ctor or copy-assignment operator when UDT contains a zero-sized array }; int a[]; void bar() { int a[]; // error C2133: 'a' : unknown size } Now, this needs some explaination too.

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  • C++ Template Classes Circular Dependency Problem

    - by TomWij
    We have two classes: template<typename T, typename Size, typename Stack, typename Sparse> class Matrix and template<typename T, typename Size> class Iterator Matrix should be able to return begin and end iterators and Iterator will keep a referrence to the Matrix to access the elements via it's interface. We don't want Iterator to depend on the internal storage of the Matrix to prevent coupling. How can we solve this cyclic dependency problem? (The internal Storage class has the same template parameters as the Matrix class and the same access procedures as the Matrix itself)

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  • How to handle downgrade subscription for SaaS application

    - by user635800
    I am currently launching a SaaS web application. I want to have subscription packages such as: Premium: 5 users, 20 widgets, 20 MB storage Basic: 2 users, 10 widgets, 50 MB storage I want to allow companies to upgrade and downgrade packages at any time. The problem I am having is what if the company is on the premium package and has 5 users, 20 widgets, and wants to downgrade to the "basic" package. How do I handle that? Do I flag an error and say "You cannot downgrade" or do I take them to a page to remove the "extra" users and widgets? Any advice or examples of how other companies do it would be great!!

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  • Communicate between content script and options page

    - by Gaurang Tandon
    I have seen many questions already and all are about background page to content script. Summary My extension has an options page, and a content script. The content script handles the storage functionality (chrome.storage manipulation). Whenever, a user changes a setting in the options page, I want to send a message to the content script to store the new data. My code: options.js var data = "abcd"; // let data chrome.tabs.query({ active: true, currentWindow: true }, function (tabs) { chrome.tabs.sendMessage(tabs[0].id, "storeData:" + data, function(response){ console.log(response); // gives undefined :( }); }); content script js chrome.runtime.onMessage.addListener(function(request, sender, sendResponse) { // not working }); My question: Why isn't the approach not working? Is there any other (better) approach for this procedure.

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  • How to find a duplicate element in an array of shuffled consecutive integers?

    - by SysAdmin
    I recently came across a question somewhere Suppose you have an array of 1001 integers. The integers are in random order, but you know each of the integers is between 1 and 1000 (inclusive). In addition, each number appears only once in the array, except for one number, which occurs twice. Assume that you can access each element of the array only once. Describe an algorithm to find the repeated number. If you used auxiliary storage in your algorithm, can you find an algorithm that does not require it? what i am interested to know is the second part. i.e without using auxiliary storage . do you have any idea?

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  • Error using CreateFileMapping - C

    - by Jamie Keeling
    Hello, I am using the tutorial on this MSDN link to implement a way of transferring data from one process to another. Although I was advised in an earlier question to use the Pipe methods, due to certain constraints I have no choice but to use the CreateFileMapping method. Now, i've succesfully managed to make two seperate window form projects within the same solution and by editing some properties both of the forms load at the same time. Furthermore I have managed to implement the code given in the MSDN sample into the first (Producer) and second (Consumer) program without any compilation errors. The problem I am having now is when I run the first program and try to create the handle to the mapped file, I am given an error saying it was unsuccesful and I do not understand why this is happening. I have added both the Producer and Consumer code files to demonstrate what I am trying to do. Producer: #include <windows.h> #include <stdio.h> #include <conio.h> //File header definitions #define IDM_FILE_ROLLDICE 1 #define IDM_FILE_QUIT 2 #define BUF_SIZE 256 TCHAR szName[]=TEXT("Global\\MyFileMappingObject"); TCHAR szMsg[]=TEXT("Message from first process!"); void AddMenus(HWND); LRESULT CALLBACK WindowFunc(HWND, UINT, WPARAM, LPARAM); ////Standard windows stuff - omitted to save space. ////////////////////// // WINDOWS FUNCTION // ////////////////////// LRESULT CALLBACK WindowFunc(HWND hMainWindow, UINT message, WPARAM wParam, LPARAM lParam) { WCHAR buffer[256]; LPCTSTR pBuf; struct DiceData storage; HANDLE hMapFile; switch(message) { case WM_CREATE: { // Create Menus AddMenus(hMainWindow); } break; case WM_COMMAND: // Intercept menu choices switch(LOWORD(wParam)) { case IDM_FILE_ROLLDICE: { //Roll dice and store results in variable //storage = RollDice(); ////Copy results to buffer //swprintf(buffer,255,L"Dice 1: %d, Dice 2: %d",storage.dice1,storage.dice2); ////Show via message box //MessageBox(hMainWindow,buffer,L"Dice Result",MB_OK); hMapFile = CreateFileMapping( (HANDLE)0xFFFFFFFF, // use paging file NULL, // default security PAGE_READWRITE, // read/write access 0, // maximum object size (high-order DWORD) BUF_SIZE, // maximum object size (low-order DWORD) szName); // name of mapping object if (hMapFile == NULL) { MessageBox(hMainWindow,L"Could not create file mapping object",L"Error",NULL); return 1; } pBuf = (LPTSTR) MapViewOfFile(hMapFile, // handle to map object FILE_MAP_ALL_ACCESS, // read/write permission 0, 0, BUF_SIZE); if (pBuf == NULL) { MessageBox(hMainWindow,L"Could not map view of file",L"Error",NULL); CloseHandle(hMapFile); return 1; } CopyMemory((PVOID)pBuf, szMsg, (_tcslen(szMsg) * sizeof(TCHAR))); _getch(); UnmapViewOfFile(pBuf); CloseHandle(hMapFile); } break; case IDM_FILE_QUIT: SendMessage(hMainWindow, WM_CLOSE, 0, 0); break; } break; case WM_DESTROY: PostQuitMessage(0); break; } return DefWindowProc(hMainWindow, message, wParam, lParam); } // //Setup menus // Consumer: #include <windows.h> #include <stdio.h> #include <conio.h> //File header definitions #define IDM_FILE_QUIT 1 #define IDM_FILE_POLL 2 #define BUF_SIZE 256 TCHAR szName[]=TEXT("Global\\MyFileMappingObject"); //Prototypes void AddMenus(HWND); LRESULT CALLBACK WindowFunc(HWND, UINT, WPARAM, LPARAM); //More standard windows creation, again omitted. ////////////////////// // WINDOWS FUNCTION // ////////////////////// LRESULT CALLBACK WindowFunc(HWND hMainWindow, UINT message, WPARAM wParam, LPARAM lParam) { HANDLE hMapFile; LPCTSTR pBuf; switch(message) { case WM_CREATE: { // Create Menus AddMenus(hMainWindow); break; } case WM_COMMAND: { // Intercept menu choices switch(LOWORD(wParam)) { case IDM_FILE_POLL: { hMapFile = OpenFileMapping( FILE_MAP_ALL_ACCESS, // read/write access FALSE, // do not inherit the name szName); // name of mapping object if (hMapFile == NULL) { MessageBox(hMainWindow,L"Could not open file mapping object",L"Error",NULL); return 1; } pBuf = (LPTSTR) MapViewOfFile(hMapFile, // handle to map object FILE_MAP_ALL_ACCESS, // read/write permission 0, 0, BUF_SIZE); if (pBuf == NULL) { MessageBox(hMainWindow,L"Could not map view of file",L"Error",NULL); CloseHandle(hMapFile); return 1; } MessageBox(NULL, pBuf, TEXT("Process2"), MB_OK); UnmapViewOfFile(pBuf); CloseHandle(hMapFile); break; } case IDM_FILE_QUIT: SendMessage(hMainWindow, WM_CLOSE, 0, 0); break; } break; } case WM_DESTROY: { PostQuitMessage(0); break; } } return DefWindowProc(hMainWindow, message, wParam, lParam); } // //Setup menus // It's by no means tidy and final but it's just a start, thanks for any help.

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  • Java Http request on api.stackexchange with json response

    - by taoder
    I'm trying to use the api-stackexchange with java but when I do the request and try to parse the response with a json parser I have an error. public ArrayList<Question> readJsonStream(InputStream in) throws IOException { JsonReader reader = new JsonReader(new InputStreamReader(in, "UTF-8")); reader.setLenient(true); try { System.out.println(reader.nextString()); // ? special character return readItem(reader); } finally { reader.close(); } } public ArrayList<Question> readItem(JsonReader reader) throws IOException { ArrayList<Question> questions = new ArrayList<Question>(); reader.beginObject(); while (reader.hasNext()) { System.out.println("here");//not print the error is before String name = reader.nextName(); if (name.equals("items")) { questions = readQuestionsArray(reader); } } reader.endObject(); return questions; } public final static void main(String[] args) throws Exception { URIBuilder builder = new URIBuilder(); builder.setScheme("http").setHost("api.stackexchange.com").setPath("/2.0/search") .setParameter("site", "stackoverflow") .setParameter("intitle" ,"workaround") .setParameter("tagged","javascript"); URI uri = builder.build(); String surl = fixEncoding(uri.toString()+"&filter=!)QWRa9I-CAn0PqgUwq7)DVTM"); System.out.println(surl); Test t = new Test(); try { URL url = new URL(surl); t.readJsonStream(url.openStream()); } catch (IOException e) { e.printStackTrace(); } } And the error is: com.google.gson.stream.MalformedJsonException: Expected literal value at line 1 column 19 Here is an example of the Json : { "items": [ { "question_id": 10842231, "score": 0, "title": "How to push oath token to LocalStorage or LocalSession and listen to the Storage Event? (SoundCloud Php/JS bug workaround)", "tags": [ "javascript", "javascript-events", "local-storage", "soundcloud" ], "answers": [ { "question_id": 10842231, "answer_id": 10857488, "score": 0, "is_accepted": false } ], "link": "http://stackoverflow.com/questions/10842231/how-to-push-oath-token-to-localstorage-or-localsession-and-listen-to-the-storage", "is_answered": false },... So what's the problem? Is the Json really malformed? Or did I do something not right? Thanks, Anthony

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  • webOS style view switching on iPhone app

    - by Taylor Satula
    Hello, I have been working with a iPhone app that I would like to have switch views like the Palm Pre does for multitasking. I know the usual way of switching views by using the black bar at the bottom of the app but the app I am working on does not lend itself to having a big black bar in the way (see attached picture #1). I guess my question is, how do I shrink the current view (Current Location window) and show other views on the sides? (see attached picture #2) Then be able to swipe left and right to view other views. I have no idea how to do this and would be eternally grateful if someone could help me out with this. http://www.threepixeldrift.com/images/deep-storage/webOScardapp1.jpg http://www.threepixeldrift.com/images/deep-storage/webOScardapp2.jpg

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  • e2fsck extremely slow, although enough memory exists

    - by kaefert
    I've got this external USB-Disk: kaefert@blechmobil:~$ lsusb -s 2:3 Bus 002 Device 003: ID 0bc2:3320 Seagate RSS LLC As can be seen in this dmesg output, there is some problem that prevents that disk from beeing mounted: kaefert@blechmobil:~$ dmesg ... [ 113.084079] usb 2-1: new high-speed USB device number 3 using ehci_hcd [ 113.217783] usb 2-1: New USB device found, idVendor=0bc2, idProduct=3320 [ 113.217787] usb 2-1: New USB device strings: Mfr=2, Product=3, SerialNumber=1 [ 113.217790] usb 2-1: Product: Expansion Desk [ 113.217792] usb 2-1: Manufacturer: Seagate [ 113.217794] usb 2-1: SerialNumber: NA4J4N6K [ 113.435404] usbcore: registered new interface driver uas [ 113.455315] Initializing USB Mass Storage driver... [ 113.468051] scsi5 : usb-storage 2-1:1.0 [ 113.468180] usbcore: registered new interface driver usb-storage [ 113.468182] USB Mass Storage support registered. [ 114.473105] scsi 5:0:0:0: Direct-Access Seagate Expansion Desk 070B PQ: 0 ANSI: 6 [ 114.474342] sd 5:0:0:0: [sdb] 732566645 4096-byte logical blocks: (3.00 TB/2.72 TiB) [ 114.475089] sd 5:0:0:0: [sdb] Write Protect is off [ 114.475092] sd 5:0:0:0: [sdb] Mode Sense: 43 00 00 00 [ 114.475959] sd 5:0:0:0: [sdb] Write cache: enabled, read cache: enabled, doesn't support DPO or FUA [ 114.477093] sd 5:0:0:0: [sdb] 732566645 4096-byte logical blocks: (3.00 TB/2.72 TiB) [ 114.501649] sdb: sdb1 [ 114.502717] sd 5:0:0:0: [sdb] 732566645 4096-byte logical blocks: (3.00 TB/2.72 TiB) [ 114.504354] sd 5:0:0:0: [sdb] Attached SCSI disk [ 116.804408] EXT4-fs (sdb1): ext4_check_descriptors: Checksum for group 3976 failed (47397!=61519) [ 116.804413] EXT4-fs (sdb1): group descriptors corrupted! ... So I went and fired up my favorite partition manager - gparted, and told it to verify and repair the partition sdb1. This made gparted call e2fsck (version 1.42.4 (12-Jun-2012)) e2fsck -f -y -v /dev/sdb1 Although gparted called e2fsck with the "-v" option, sadly it doesn't show me the output of my e2fsck process (bugreport https://bugzilla.gnome.org/show_bug.cgi?id=467925 ) I started this whole thing on Sunday (2012-11-04_2200) evening, so about 48 hours ago, this is what htop says about it now (2012-11-06-1900): PID USER PRI NI VIRT RES SHR S CPU% MEM% TIME+ Command 3704 root 39 19 1560M 1166M 768 R 98.0 19.5 42h56:43 e2fsck -f -y -v /dev/sdb1 Now I found a few posts on the internet that discuss e2fsck running slow, for example: http://gparted-forum.surf4.info/viewtopic.php?id=13613 where they write that its a good idea to see if the disk is just that slow because maybe its damaged, and I think these outputs tell me that this is not the case in my case: kaefert@blechmobil:~$ sudo hdparm -tT /dev/sdb /dev/sdb: Timing cached reads: 3562 MB in 2.00 seconds = 1783.29 MB/sec Timing buffered disk reads: 82 MB in 3.01 seconds = 27.26 MB/sec kaefert@blechmobil:~$ sudo hdparm /dev/sdb /dev/sdb: multcount = 0 (off) readonly = 0 (off) readahead = 256 (on) geometry = 364801/255/63, sectors = 5860533160, start = 0 However, although I can read quickly from that disk, this disk speed doesn't seem to be used by e2fsck, considering tools like gkrellm or iotop or this: kaefert@blechmobil:~$ iostat -x Linux 3.2.0-2-amd64 (blechmobil) 2012-11-06 _x86_64_ (2 CPU) avg-cpu: %user %nice %system %iowait %steal %idle 14,24 47,81 14,63 0,95 0,00 22,37 Device: rrqm/s wrqm/s r/s w/s rkB/s wkB/s avgrq-sz avgqu-sz await r_await w_await svctm %util sda 0,59 8,29 2,42 5,14 43,17 160,17 53,75 0,30 39,80 8,72 54,42 3,95 2,99 sdb 137,54 5,48 9,23 0,20 587,07 22,73 129,35 0,07 7,70 7,51 16,18 2,17 2,04 Now I researched a little bit on how to find out what e2fsck is doing with all that processor time, and I found the tool strace, which gives me this: kaefert@blechmobil:~$ sudo strace -p3704 lseek(4, 41026998272, SEEK_SET) = 41026998272 write(4, "\212\354K[_\361\3nl\212\245\352\255jR\303\354\312Yv\334p\253r\217\265\3567\325\257\3766"..., 4096) = 4096 lseek(4, 48404766720, SEEK_SET) = 48404766720 read(4, "\7t\260\366\346\337\304\210\33\267j\35\377'\31f\372\252\ffU\317.y\211\360\36\240c\30`\34"..., 4096) = 4096 lseek(4, 41027002368, SEEK_SET) = 41027002368 write(4, "\232]7Ws\321\352\t\1@[+5\263\334\276{\343zZx\352\21\316`1\271[\202\350R`"..., 4096) = 4096 lseek(4, 48404770816, SEEK_SET) = 48404770816 read(4, "\17\362r\230\327\25\346//\210H\v\311\3237\323K\304\306\361a\223\311\324\272?\213\tq \370\24"..., 4096) = 4096 lseek(4, 41027006464, SEEK_SET) = 41027006464 write(4, "\367yy>x\216?=\324Z\305\351\376&\25\244\210\271\22\306}\276\237\370(\214\205G\262\360\257#"..., 4096) = 4096 lseek(4, 48404774912, SEEK_SET) = 48404774912 read(4, "\365\25\0\21|T\0\21}3t_\272\373\222k\r\177\303\1\201\261\221$\261B\232\3142\21U\316"..., 4096) = 4096 ^CProcess 3704 detached around 16 of these lines every second, so 4 read and 4 write operations every second, which I don't consider to be a lot.. And finally, my question: Will this process ever finish? If those numbers from fseek (48404774912) represent bytes, that would be something like 45 gigabytes, with this beeing a 3 terrabyte disk, which would give me 134 days to go, if the speed stays constant, and e2fsck scans the disk like this completly and only once. Do you have some advice for me? I have most of the data on that disk elsewhere, but I've put a lot of hours into sorting and merging it to this disk, so I would prefer to getting this disk up and running again, without formatting it anew. I don't think that the hardware is damaged since the disk is only a few months and since I can't see any I/O errors in the dmesg output. UPDATE: I just looked at the strace output again (2012-11-06_2300), now it looks like this: lseek(4, 1419860611072, SEEK_SET) = 1419860611072 read(4, "3#\f\2447\335\0\22A\355\374\276j\204'\207|\217V|\23\245[\7VP\251\242\276\207\317:"..., 4096) = 4096 lseek(4, 43018145792, SEEK_SET) = 43018145792 write(4, "]\206\231\342Y\204-2I\362\242\344\6R\205\361\324\177\265\317C\334V\324\260\334\275t=\10F."..., 4096) = 4096 lseek(4, 1419860615168, SEEK_SET) = 1419860615168 read(4, "\262\305\314Y\367\37x\326\245\226\226\320N\333$s\34\204\311\222\7\315\236\336\300TK\337\264\236\211n"..., 4096) = 4096 lseek(4, 43018149888, SEEK_SET) = 43018149888 write(4, "\271\224m\311\224\25!I\376\16;\377\0\223H\25Yd\201Y\342\r\203\271\24eG<\202{\373V"..., 4096) = 4096 lseek(4, 1419860619264, SEEK_SET) = 1419860619264 read(4, ";d\360\177\n\346\253\210\222|\250\352T\335M\33\260\320\261\7g\222P\344H?t\240\20\2548\310"..., 4096) = 4096 lseek(4, 43018153984, SEEK_SET) = 43018153984 write(4, "\360\252j\317\310\251G\227\335{\214`\341\267\31Y\202\360\v\374\307oq\3063\217Z\223\313\36D\211"..., 4096) = 4096 So the numbers in the lseek lines before the reads, like 1419860619264 are already a lot bigger, standing for 1.29 terabytes if those numbers are bytes, so it doesn't seem to be a linear progress on a big scale, maybe there are only some areas that need work, that have big gaps in between them. UPDATE2: Okey, big disappointment, the numbers are back to very small again (2012-11-07_0720) lseek(4, 52174548992, SEEK_SET) = 52174548992 read(4, "\374\312\22\\\325\215\213\23\0357U\222\246\370v^f(\312|f\212\362\343\375\373\342\4\204mU6"..., 4096) = 4096 lseek(4, 46603526144, SEEK_SET) = 46603526144 write(4, "\370\261\223\227\23?\4\4\217\264\320_Am\246CQ\313^\203U\253\274\204\277\2564n\227\177\267\343"..., 4096) = 4096 so either e2fsck goes over the data multiple times, or it just hops back and forth multiple times. Or my assumption that those numbers are bytes is wrong. UPDATE3: Since it's mentioned here http://forums.fedoraforum.org/showthread.php?t=282125&page=2 that you can testisk while e2fsck is running, i tried that, though not with a lot of success. When asking testdisk to display the data of my partition, this is what I get: TestDisk 6.13, Data Recovery Utility, November 2011 Christophe GRENIER <[email protected]> http://www.cgsecurity.org 1 P Linux 0 4 5 45600 40 8 732566272 Can't open filesystem. Filesystem seems damaged. And this is what strace currently gives me (2012-11-07_1030) lseek(4, 212460343296, SEEK_SET) = 212460343296 read(4, "\315Mb\265v\377Gn \24\f\205EHh\2349~\330\273\203\3375\206\10\r3=W\210\372\352"..., 4096) = 4096 lseek(4, 47347830784, SEEK_SET) = 47347830784 write(4, "]\204\223\300I\357\4\26\33+\243\312G\230\250\371*m2U\t_\215\265J \252\342Pm\360D"..., 4096) = 4096 (times are in CET)

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  • Custom Expression in Linq-to-Sql Designer

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    According to Microsoft: http://msdn.microsoft.com/de-de/library/system.data.linq.mapping.columnattribute.expression.aspx It's possible to add expression to the Linq-to-SQL Mapping. But how to configure or add them in Visual Studio in the Designer? Problem, when I add it manual to thex XYZ.designer.cs it on change it will be lost. //------------------------------------------------------------------------------ // <auto-generated> // This code was generated by a tool. // Runtime Version:2.0.50727.4927 // // Changes to this file may cause incorrect behavior and will be lost if // the code is regenerated. // </auto-generated> //------------------------------------------------------------------------------ This is generated: [Column(Name="id", Storage="_id", DbType="Int")] public System.Nullable<int> id { ... But i need something like this [Column(Name="id", Storage="_id", DbType="Int", Expression="Max(id)")] public System.Nullable<int> id { ... Thanks.

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    I have some questions about the cache directory in android. Does anyone knows the limit for each app's cache directory? Also what will happen if there is not enough disk space to cache data? All I know is when the device runs low on storage, the files here (cache directory)will be the ones that get deleted first and each app has its own cache directory. Now, are the files of other app's cache directory will be cleared to accommodate my app's request to add files in the cache dir when there is not enough storage?

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  • Performance - User defined query / filter to search data

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    What is the best way to design a system where users can create their own criterias to search data ? By "design" i mean, data storage, data access layer and search structure. We will actually refactor an existing application which is written in C# and ASP .NET and we don't want to change the infrastructure. Our main issue is performance and we use MSSQL and DevExpress to build queries. Some queries run in 4-5 minutes and all the columns included in the queries have indexes. When i check queries, i see that DevExpress builds too many "exists" clauses and i'm not happy with that because i have doubts that some of these queries skip some indexes. What may be the alternatives to DevExpress? NHibernate or Entity Framework? Can we build dynamic criteria system and store these to database in both of them ? And also do we need any alternative storage like a lucene index or OLAP database?

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  • What is the cost in bytes for the overhead of a sql_variant column in SQL Server?

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    I have a table, which contains many columns of float data type with 15 digit precision. Each column consumes 8 bytes of storage. Most of the time the data does not require this amount of precision and could be stored as a real data type. In many cases the value can be 0, in which case I could get away with storing a single byte. My goal here is to optimize space storage requirements, which is an issue I am facing working with a SQL Express 4GB database size limit. If byte, real and float data types are stored in a sql_variant column there is obviously some overhead involved in storing these values. What is the cost of this overhead? I would then need to evaluate whether I would actually end up in significant space savings (or not) switching to using sql_variant column data types. Thanks, Elan

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  • Implementing events to communicate between two processes - C

    - by Jamie Keeling
    Hello all! I have an application consisting of two windows, one communicates to the other and sends it a struct constaining two integers (In this case two rolls of a dice). I will be using events for the following circumstances: Process a sends data to process b, process b displays data Process a closes, in turn closing process b Process b closes a, in turn closing process a I have noticed that if the second process is constantly waiting for the first process to send data then the program will be just sat waiting, which is where the idea of implementing threads on each process occurred and I have started to implement this already. The problem i'm having is that I don't exactly have a lot of experience with threads and events so I'm not sure of the best way to actually implement what I want to do. Following is a small snippet of what I have so far in the producer application; Create thread: case IDM_FILE_ROLLDICE: { hDiceRoll = CreateThread( NULL, // lpThreadAttributes (default) 0, // dwStackSize (default) ThreadFunc(hMainWindow), // lpStartAddress NULL, // lpParameter 0, // dwCreationFlags &hDiceID // lpThreadId (returned by function) ); } break; The data being sent to the other process: DWORD WINAPI ThreadFunc(LPVOID passedHandle) { HANDLE hMainHandle = *((HANDLE*)passedHandle); WCHAR buffer[256]; LPCTSTR pBuf; LPVOID lpMsgBuf; LPVOID lpDisplayBuf; struct diceData storage; HANDLE hMapFile; DWORD dw; //Roll dice and store results in variable storage = RollDice(); hMapFile = CreateFileMapping( (HANDLE)0xFFFFFFFF, // use paging file NULL, // default security PAGE_READWRITE, // read/write access 0, // maximum object size (high-order DWORD) BUF_SIZE, // maximum object size (low-order DWORD) szName); // name of mapping object if (hMapFile == NULL) { dw = GetLastError(); MessageBox(hMainHandle,L"Could not create file mapping object",L"Error",MB_OK); return 1; } pBuf = (LPTSTR) MapViewOfFile(hMapFile, // handle to map object FILE_MAP_ALL_ACCESS, // read/write permission 0, 0, BUF_SIZE); if (pBuf == NULL) { MessageBox(hMainHandle,L"Could not map view of file",L"Error",MB_OK); CloseHandle(hMapFile); return 1; } CopyMemory((PVOID)pBuf, &storage, (_tcslen(szMsg) * sizeof(TCHAR))); //_getch(); MessageBox(hMainHandle,L"Completed!",L"Success",MB_OK); UnmapViewOfFile(pBuf); return 0; } I'm trying to find out how I would integrate an event with the threaded code to signify to the other process that something has happened, I've seen an MSDN article on using events but it's just confused me if anything, I'm coming up on empty whilst searching on the internet too. Thanks for any help Edit: I can only use the Create/Set/Open methods for events, sorry for not mentioning it earlier.

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