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  • What is the most efficient way to store a mapping "key -> event stream"?

    - by jkff
    Suppose there are ~10,000's of keys, where each key corresponds to a stream of events. I'd like to support the following operations: push(key, timestamp, event) - pushes event to the event queue for key, marked with the given timestamp. It is guaranteed that event timestamps for a particular key are pushed in sorted or almost sorted order. tail(key, timestamp) - get all events for key since the given timestamp. Usually the timestamp requests for a given key are almost monotonically increasing, almost synchronously with pushes for the same key. This stuff has to be persistent (although it is not absolutely necessary to persist pushes immediately and to keep tails with pushes strictly in sync), so I'm going to use some kind of database. What is the optimal kind of database structure for this task? Would it be better to use a relational database, a key-value storage, or something else?

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  • How can you query for an object using one of its properties' id

    - by James Smith
    I have two entities, say, House and People, where multiple people can live in one house. It's a unidirectional link where each Person has a field for which House they belong to, so the Person table has a column named house_id. I need to be able to return all the Person objects who belong to a certain House, but I only have the id of the house. This can be done like this: House house = houseDAO.findById(houseId); List people = session.createCriteria(Person.class).add(Restrictions.eq("house", house)).list(); But since I don't need the house, that's adding an unnecessary query. I've tried to do: session.createCriteria(Person.class).add(Restrictions.eq("house_id", houseId)).list(); But that doesn't work because house_id is not a property, it's a database column. I could just add an sql restriction, but is there a hibernate way of doing this?

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  • How to control the memory size of continuously running windows service?

    - by Snowill
    Hi, I have created a windows service which is continuously polling a database. For this purpose i have a timer in place. Ever time i am querying a database table i open a connection and close it immediately after my work is done. Right now i am doing this every 20 seconds for testing purpose, but later this time might increase to 5 - 10 minutes. What happens is everytime the database table is polled there is an increase of 10-12 KB in the size of the memory of the service running. This i can see in the task manager. Is there any way to control this.

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  • adding a flash object to FancyBox using jquery swfobject

    - by Freeman
    Fellows, I dont seem to be getting a solution. I have a a video gallery which I create by dynamically from a database. I have managed to create a flash object which plays well without FancyBox, however I want a person to click on the gallery and then an swobject is created which will then be show on a fancybox. Here is part of my javascript which is not working. $.ajax({ data:"search=vids&id="+ art, type: "POST", url: "doyit.php", success: function(msg){ $(".videogallery").html('<h3>Click to view videos of '+name+'</h3>'+msg); $('.video').bind('click',function(ev){ var vid=$(this).attr("href"); var img=$(this).find("img").attr("src") $(this).flash({swf: "mediaplayer.swf", flashvars: { file: vid, image: img } }) $(this).fancybox( { ajax:{ type:"POST"}, 'padding' : 0, 'autoScale' : false, 'transitionIn' : 'none', 'transitionOut' : 'none', 'title' : this.title, 'width' : 680, 'height' : 495 } ); $(this).unbind(ev) return false; }) } Any suggestions?

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  • MySQL or SQL Server

    - by user203708
    I'm creating an application that I want to run on either MySQL or SQL Server (not both at the same time) I've created two PHP classes DatabaseMySQL and DatabaseSQLSVR and I'd like my application to know which database class to use based on a constant set up at install. define(DB_TYPE, "mysql"); // or "sqlsrv" I'm trying to think of the best way to handle this. My thought is to do an "if else" wherever I instantiate the database: $db = (DB_TYPE == "mysql") ? new DatabaseMySQL : new DatabaseSQLSVR; I know there has to be a better way of doing this though. Suppose I want to add a third database type later; I'll have to go and redo all my code. Yuk!! Any help would be much appreciated. Thank

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  • CakePHP call to member function on non-object

    - by joec
    I have the following Model and Controller files, and when i visit this url, http://....../pois/index i get this error: Notice (8): Undefined property: PoisController::$Poi [APP/controllers/pois_controller.php, line 5] Fatal error: Call to a member function find() on a non-object in /home/joecoyle/public_html/app/controllers/pois_controller.php on line 5 The Model is this, called poi.php: <?php class Poi extends AppModel { } ?> And the controller is this, named pois_controller.php <?php class PoisController extends AppController { function index(){ $this->set('pois',$this->Poi->find('all')); } } ?> As i am new to CakePHP i am not sure what is causing this error, as everything seems to be named, right, and i am following the tutorial on the CakePHP site... Thanks

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  • When do instance variables get initialized and values assigned?

    - by AKh
    When doees the instance variable get initialized? Is it after the constructor block is done or before it? Consider this example: public abstract class Parent { public Parent(){ System.out.println("Parent Constructor"); init(); } public void init(){ System.out.println("parent Init()"); } } public class Child extends Parent { private Integer attribute1; private Integer attribute2 = null; public Child(){ super(); System.out.println("Child Constructor"); } public void init(){ System.out.println("Child init()"); super.init(); attribute1 = new Integer(100); attribute2 = new Integer(200); } public void print(){ System.out.println("attribute 1 : " +attribute1); System.out.println("attribute 2 : " +attribute2); } } public class Tester { public static void main(String[] args) { Parent c = new Child(); ((Child)c).print(); } } OUTPUT: Parent Constructor Child init() parent Init() Child Constructor attribute 1 : 100 attribute 2 : null When the memory for the atribute 1 & 2 are allocated in the heap ? Curious to know why is attribute 2 is NULL ? Are there any design flaws?

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  • Some specific questions about object oriented and MVC design.

    - by Samn
    I have two objects, Users and Mail. Users create Mail objects and send them to other users. If I wanted to get all mail for a User, I could create a method like GetMail() that would return an array of Mail objects owned by that User. But if I wanted to get all mail across the system, what "type" of object would be responsible for that? To solve this problem, I usually create a Manager, which is an object responsible for dealing with a collection of a particular type of object. MailManager deals with collections of Mail objects. GetMailForUser() is one method, GetAllMail() is another method. The User objects invokes the MailManager and executes GetMailForUser(me). Is this stupid? When a user executes the controller CreateMail, a new instance of the Mail object is created. The Mail object, seeing it is creating a new Mail of type 'sent', decides to go ahead and create a second Mail object for the recipient, of type 'received'. Creating one Mail object triggers the creation of a second Mail object. Is this stupid? Should the controller have created both Mail objects, or just the first 'sent' one? When two Users are friends, the association is stored in a table of Relationships. I use a simple object for Relationships. A RelationshipManager has a method called GetFriendsForUser(). The User object has a method GetFriends(), which invokes the RelationshipManager. Is this stupid?

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  • How to check if two records have a self-referencing relation?

    - by Machine
    Consider the following schema with users and their collegues (friends): Users User: columns: user_id: name: user_id as userId type: integer(8) unsigned: 1 primary: true autoincrement: true first_name: name: first_name as firstName type: string(45) notnull: true last_name: name: last_name as lastName type: string(45) notnull: true email: type: string(45) notnull: true unique: true relations: Collegues: class: User local: invitor foreign: invitee refClass: CollegueStatus equal: true onDelete: CASCADE onUpdate: CASCADE Join table: CollegueStatus: columns: invitor: type: integer(8) unsigned: 1 primary: true invitee: type: integer(8) unsigned: 1 primary: true status: type: enum(8) values: [pending, accepted, denied] default: pending notnull: true Now, let's say I two records, one for the user making a HTTP request (the logged in user), and one record for a user he wants to send a message to. I want to check if these users are collegues. Questions: Does Doctrine have any pre-build functionality to check if two records with with self-relations are related? If not, how would you write a method to check this? Where would you put said method? (In the User-class, UserTable-class etc) I could probably do something like this: public function (User $user1, User $user2) { // Ensure we load collegues if $user1 was fetched with DQL that // doesn't load this relation $collegues = $user1->get('Collegues'); $areCollegues = false; foreach($collegues as $collegue) { if($collegue['userId'] === $user2['userId']) { $areCollegues = true; break; } } return $areCollegues; } But this looks a neither efficient nor pretty. I just feel that it should be solved already for self-referencing relations to be nice to use.

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  • Domain Model and Contracts

    - by devoured elysium
    I am modelling a DVD Rental Store: A Client gives its clientNumber to the System. The System checks whenever the given clientNumber is valid. The Client gives the name of the DVD he wants to rent. ... n. ...I will later have to form an association between a new instance of "RentDVD" class concept to the current Client c. My Domain Model is something like: I've made the Contract for the first and second operations as: Preconditions: none Postconditions: there exists a Client c such that c.clientNumber = clientNumber. Now, I don't know if I should form an association between this Client c and the DVDStore(that I intend to use as front-end). If I don't make the association, how will I later be able to "reference" this same Client? Should I be making an association between Client and a different concept? Thanks

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  • Are there any e-commerce websites that use NoSQL databases

    - by Saif Bechan
    I have read a lot lately about 'NoSQL' databases such as CouchDB, MongoDB etc. Most of the websites I have seen using this are mainly text based websites such as The New York Times and Source forge. I was wondering if you could apply this to websites where payment is a huge issue. I am thinking of the following issues: How well can you secure the data Do these system provide an easy backup/restore machanism How are transactions handled commit/rollback I have read the following articles that cover some aspects: Can I do transactions and locks in CouchDB? Pros/Cons of document based database vs relational database In these posts the aspect of transactions if covered. However the questions of security and backups is not covered. Can someone shed some light on this subject? And if possible, does anyone know of some e-commerce websites that have successfully implemented the document based database.

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  • error in mysql syntax in vb.net

    - by user225269
    I get this error, while I'm testing the code below: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '[student](ID, LASTNAME, FIRSTNAME, SCHOOL) VALUES ('333', 'aaa', 'aaa', 'aaa')' at line 1 I just recycled the code that I used in manipulating ms sql database. So the syntax must be wrong. What might be the correct syntax for adding records into mysql database? Here is my current code: idnum = TextBox1.Text lname = TextBox2.Text fname = TextBox3.Text skul = TextBox4.Text Using sqlcon As New MySqlConnection("Server=localhost; Database=testing;Uid=root;Pwd=nitoryolai123$%^;") sqlcon.Open() Dim sqlcom As New MySqlCommand() sqlcom.Connection = sqlcon sqlcom.CommandText = "INSERT INTO [student](ID, LASTNAME, FIRSTNAME, SCHOOL) VALUES (@ParameterID, @ParameterLastName, @ParameterFirstName, @ParameterSchool)" sqlcom.Parameters.AddWithValue("@ParameterID", TextBox1.Text) sqlcom.Parameters.AddWithValue("@ParameterLastName", TextBox2.Text) sqlcom.Parameters.AddWithValue("@ParameterFirstName", TextBox3.Text) sqlcom.Parameters.AddWithValue("@ParameterSchool", TextBox4.Text) sqlcom.ExecuteNonQuery() End Using Please help, thanks

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  • Error in IE8 Browser -> Message: Object doesn't support this property or method

    - by tibin mathew
    Hi All, In my joomla project(http://crystalwrightlive.com) home page there is one sliding banner section, but this banner not working in IE browser (working fine in FF browser) and showing following error: Webpage error details User Agent: Mozilla/4.0 (compatible; MSIE 8.0; Windows NT 5.1; Trident/4.0; GTB6; InfoPath.2) Timestamp: Sat, 8 May 2010 06:42:15 UTC Message: Object doesn't support this property or method Line: 1 Char: 1 Code: 0 URI: http://crystalwrightlive.com/index.php In index page included a jquery file: http://ajax.googleapis.com/ajax/libs/jquery/1.3.2/jquery.min.js when i removed this JS file, no error but this JQuery file needed for this sliding banner. How can i fix this issue, Please anyone help me!!!!

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  • SQL Server: query database user roles for all databases in server

    - by atricapilla
    I would like to make a query for database user roles for all databases in my sql server instance. I modified a query from sp_helpuser: select u.name ,case when (r.principal_id is null) then 'public' else r.name end ,l.default_database_name ,u.default_schema_name ,u.principal_id from sys.database_principals u left join (sys.database_role_members m join sys.database_principals r on m.role_principal_id = r.principal_id) on m.member_principal_id = u.principal_id left join sys.server_principals l on u.sid = l.sid where u.type <> 'R' How can I modify this to query from all databases? What is the link between sys.databases and sys.database_principals?

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  • getting web page data as json object?

    - by encryptor
    I have a url, the data of which page i need as a json object. I ve tried xmlhttprequest and ajaxobject both but doesnt work. It doesnt even give a responseText when I give it as an alert Ill post both the code snippets here. url = http://mydomain.com:port/a/b/c AJAX : var ajaxRequest = new ajaxObject(URL); ajaxRequest.callback = function (responseText,responseStatus) { alert(responseStatus); JSONData = responseText.parseJSON(); processData(JSONData); } USING xmlhttprequest: var client = new XMLHttpRequest(); client.open('GET',URL,true ); data = JSON.parse(client.responseText); alert(data.links.length); can someone please help me out with this. I understand cross scripting may be an issue, but how to come over it? and shouldn't then too it should give the alerts as zero or null

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  • Grasp Controller, Does it really need a UI to exist?

    - by dbones
    I have a Domain model which can be in multiple states, and if these states go out of a given range it the domain should automatically react. For example I have a Car which is made of multiple things which have measurements the Engine - Rev counter and Temperature the Fuel Tank - capacity Is is plaseable to have a CarStateController, which observses the engine and the tank, and if these states go out of range IE the engine temperature goes above range, turn the engine fan on?? There is no UI, (you could argue it would show a light on the dash board, but for this case it does not) is this a valid use of a GRASP controller pattern? if not what is this CarStateController Called? Or have I completely missed the point and this should be the State Pattern?

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  • how to write a constructor...

    - by Nima
    is that correct to write a constructor like this? class A { A::A(const A& a) { .... } }; if yes, then is it correct to invoke it like this: A* other; ... A* instance = new A(*(other)); if not, what do you suggest? Thanks

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  • INET_ATON() and INET_NTOA() in PHP?

    - by blerh
    I want to store IP addresses in my database, but I also need to use them throughout my application. I read about using INET_ATON() and INET_NTOA() in my MySQL queries to get a 32-bit unsigned integer out of an IP address, which is exactly what I want as it will make searching through the database faster than using char(15). The thing is, I can't find a function that does the same sort of thing in PHP. The only thing I came across is: http://php.net/manual/en/function.ip2long.php So I tested it: $ip = $_SERVER['REMOTE_ADDR']; echo ip2long($ip); And it outputs nothing. In the example they gave it seems to work, but then again I'm not exactly sure if ip2long() does the same thing as INET_ATON(). Does someone know a PHP function that will do this? Or even a completely new solution to storing an IP address in a database? Thanks.

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  • Copying a Polymorphic object in C++

    - by doron
    I have base-class Base from which is derived Derived1, Derived2 and Derived3. I have constructed an instance for one of the the derived classes which I store as Base* a. I now need to make a deep copy of the object which I will store as Base* b. As far as I know, the normal way of copying a class is to use copy constructors and to overload operator=. However since I don't know whether a is of type Derived1, Derived2 or Derived3, I cannot think of a way of using either the copy constructor or operator=. The only way I can think of to cleanly make this work is to implement something like: class Base { public: virtual Base* Clone() = 0; }; and the implement Clone in in the derived class as in: class Derivedn : public Base { public: Base* Clone() { Derived1* ret = new Derived1; copy all the data members } }; Java tends to use Clone quite a bit is there more of a C++ way of doing this?

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  • How to check null objects in jQuery

    - by Prashant
    I am using jQuery, I want to check existence of an element in my page. I have done following code, but its not working? if ($("#btext" + i) != null){ //alert($("#btext" + i).text()); $("#btext" + i).text("Branch " + i); } Please tell me what will be the right code? Thanks

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  • Accessing a Class Member from a First-Class Function

    - by dbyrne
    I have a case class which takes a list of functions: case class A(q:Double, r:Double, s:Double, l:List[(Double)=>Double]) I have over 20 functions defined. Some of these functions have their own parameters, and some of them also use the q, r, and s values from the case class. Two examples are: def f1(w:Double) = (d:Double) => math.sin(d) * w def f2(w:Double, q:Double) = (d:Double) => d * q * w The problem is that I then need to reference q, r, and s twice when instantiating the case class: A(0.5, 1.0, 2.0, List(f1(3.0), f2(4.0, 0.5))) //0.5 is referenced twice I would like to be able to instantiate the class like this: A(0.5, 1.0, 2.0, List(f1(3.0), f2(4.0))) //f2 already knows about q! What is the best technique to accomplish this? Can I define my functions in a trait that the case class extends? EDIT: The real world application has 7 members, not 3. Only a small number of the functions need access to the members. Most of the functions don't care about them.

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  • Large tables of static data with DBGhost

    - by Paulo Manuel Santos
    We are thinking of restructuring our database development and deployment processes by using DBGhost, we want to move away from the central development database and bring the database to the source control. One of the problems we have is a big table with static data (containing translated language strings), it has close to 200K rows. I know that our best solution is to move these stings into resource files, but until we implement that, will DbGhost be able to maintain all this static data and generate our development and deployment databases in a short time? And if not is there a good alternative to filling up this table whenever we need to?

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  • How perform USort() on an Array of Objects class definition as a method?

    - by user558724
    class Contact{ public $name; public $bgcolor; public $lgcolor; public $email; public $element; public function __construct($name, $bgcolor, $lgcolor, $email, $element) { $this->name = $name; $this->bgcolor = $bgcolor; $this->lgcolor = $lgcolor; $this->email = $email; $this->element = $element; } public static function sortByName(Contact $p1, Contact $p2) { return strcmp($p1->name, $p2->name); } } class ContactList implements Iterator, ArrayAccess { protected $_label; protected $_contacts = array(); public function __construct($label) { $this->_label = $label; } public function getLabel() { return $this->_label; } public function addContact(Contact $contact) { $this->_contacts[] = $contact; } public function current() { return current($this->_contacts); } public function key() { return key($this->_contacts); } public function next() { return next($this->_contacts); } public function rewind() { return reset($this->_contacts); } public function valid() { return current($this->_contacts); } public function offsetGet($offset) { return $this->_contacts[$offset]; } public function offsetSet($offset, $data) { if (!$data instanceof Contact) throw new InvalidArgumentException('Only Contact objects allowed in a ContactList'); if ($offset == '') { $this->_contacts[] = $data; } else { $this->_contacts[$offset] = $data; } } public function offsetUnset($offset) { unset($this->_contacts[$offset]); } public function offsetExists($offset) { return isset($this->_contacts[$offset]); } public function sort($attribute = 'name') { $sortFct = 'sortBy' . ucfirst(strtolower($attribute)); if (!in_array($sortFct, get_class_methods('Contact'))) { throw new Exception('contact->sort(): Can\'t sort by ' . $attribute); } usort($this->contact, 'ContactList::' . $sortFct); } } public function Sort($property, $asc=true) { // this is where sorting logic takes place $_pd = $this->_contact->getProperty($property); if ($_pd == null) { user_error('Property '.$property.' does not exist in class '.$this->_contact->getName(), E_WARNING); return; } // set sortDescriptor ContactList::$sortProperty = $_pd; // and apply sorting usort($this->_array, array('ContactList', ($asc?'USortAsc':'USortDesc'))); } function getItems(){ return $this->_array; } class SortableItem extends ContactList { static public $sortProperty; static function USortAsc($a, $b) { /*@var $_pd ReflectionProperty*/ /* $_pd = self::$sortProperty; if ($_pd !== null) { if ($_pd->getValue($a) === $_pd->getValue($b)) return 0; else return (($_pd->getValue($a) < $_pd->getValue($b))?-1:1); } return 0; } static function USortDesc($a, $b) { return -(self::USortAsc($a,$b)); } } This approach keeps giving me PHP Warnings: usort() [function.usort]: of all kinds which I can provide later as needed to comment out those methods and definitions in order to test and fix some minor bugs of our program. **$billy parameters are already defined. $all -> addContact($billy); // --> ended up adding each contact manually above $all->Sort('name',true); $items = $all->getItems(); foreach($items as $contact) { echo $contact->__toString(); } $all->sort(); The reason for using usort is to re-arrange the order alphabetically by name but somehow is either stating that the function comparison needs to be an array or another errors which obviously I have seemed to pass. Any help would be greatly appreciated, thanks in advance.

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