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• Best data store for billions of rows

  - by Jody Powlette

  I need to be able to store small bits of data (approximately 50-75 bytes) for billions of records (~3 billion/month for a year). The only requirement is fast inserts and fast lookups for all records with the same GUID and the ability to access the data store from .net. I'm a SQL server guy and I think SQL Server can do this, but with all the talk about BigTable, CouchDB, and other nosql solutions, it's sounding more and more like an alternative to a traditional RDBS may be best due to optimizations for distributed queries and scaling. I tried cassandra and the .net libraries don't currently compile or are all subject to change (along with cassandra itself). I've looked into many nosql data stores available, but can't find one that meets my needs as a robust production-ready platform. If you had to store 36 billion small, flat records so that they're accessible from .net, what would choose and why?

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• How to maintain a pool of names ?

  - by Jacques René Mesrine

  I need to maintain a list of userids (proxy accounts) which will be dished out to multithreaded clients. Basically the clients will use the userids to perform actions; but for this question, it is not important what these actions are. When a client gets hold of a userid, it is not available to other clients until the action is completed. I'm trying to think of a concurrent data structure to maintain this pool of userids. Any ideas ? Would a ConcurrentQueue do the job ? Clients will dequeue a userid, and add back the userid when they are finished with it.

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• Howto read only one line via c++ from a data

  - by Markus Hupfauer

  i tryed to read the first line of a .dat data, but when i tryed to give to text, wich was saved in the .dat data, it print out the whole data, not only one line. the tool is also not looking after breaks or spaces :( Im using the following code: //Vocabel.dat wird eingelesen ifstream f; // Datei-Handle string s; f.open("Vocabeln.dat", ios::in); // Öffne Datei aus Parameter while (!f.eof()) // Solange noch Daten vorliegen { getline(f, s); // Lese eine Zeile cout << s; } f.close(); // Datei wieder schließen getchar(); . So could u help me please ? . Thanks a lot Markus

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• A balanced binary search tree which is also a heap

  - by saeedn

  I'm looking for a data structure where each element in it has two keys. With one of them the structure is a BST and looking at the other one, data structure is a heap. With a little search, I found a structure called Treap. It uses the heap property with a random distribution on heap keys to make the BST balanced! What I want is a Balanced BST, which can be also a heap. The BST in Treap could be unbalanced if I insert elements with heap Key in the order of my choice. Is there such a data structure?

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• implementing type inference

  - by deepblue

  well I see some interesting discussions here about static vs. dynamic typing I generally prefer static typing, due to compile type checking, better documented code,etc. However I do agree that they do clutter up the code if done the way Java does it, for example. so Im about to start building a language of my own and type inference is one of the things that I want to implement, in a functional style language... I do understand that it is a big subject, and Im not trying to create something that has not been done before, just basic inferencing... any pointers on what to read up that will help me with this? preferably something more pragmatic/practical as oppose to more theoretical category theory/type theory texts. If there's a implementation discussion text out here, with data structures/algorithms, that would just be lovely much appreciated

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• Configuration and Model-View

  - by HH

  I am using the Model-View pattern on a small application I'm writing. Here's the scenario: The model maintains a list of directories from where it can extract the data that it needs. The View has a Configuration or a Setting dialog where the user can modify this list of directories (the dialog has a JList displaying the list in addition to add and remove buttons). I need some advice from the community: The View needs to communicate these changes to the model. I thought first of adding to the model these methods: addDirectory() and removeDirectory(). But I am trying to limit the number of methods (or channels) that the View can use to communicate with and manipulate the model. Is there any good practice for this? Thank you.

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• Ruby: Read large data from stdout and stderr of an external process on Windows

  - by BinaryMuse

  Greetings, all, I need to run a potentially long-running process from Ruby on Windows and subsequently capture and parse the data from the external process's standard output and error. A large amount of data can be sent to each, but I am only necessarily interested in one line at a time (not capturing and storing the whole of the output). After a bit of research, I found that the Open3 class would take care of executing the process and giving me IO objects connected to the process's standard output and error (via popen3). Open3.popen3("external-program.bat") do |stdin, out, err, thread| # Step3.profit() ? end However, I'm not sure how to continually read from both streams without blocking the program. Since calling IO#readlines on out or err when a lot of data has been sent results in a memory allocation error, I'm trying to continuously check both streams for available input, but not having much luck with any of my implementations. Thanks in advance for any advice!

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• which is better, creating a materialized view or a new table?

  - by Carson

  I have some demanding mysql queries that are needed to grap same up-to-date datasets from 5-7 mysql tables. I am thinking of creating a table or materialized view to gather all demanding columns from other tables, so as to increase performance. If I create that table, I may need to do extra insert / update / delete operation each time other tables updated. if I create materialized view, I am worrying if the performance can be greatly improved. Because data from other tables are changing very frequently. Most likely, the view may need to be created first everytime before selecting it. Any ideas? e.g. how to cache? other extra measures I can do?

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• What data/service is where?

  - by MrTelly

  What management tools (open source or otherwise) are there to track the location of data, the services that deliver/use that data and the services themselves. If you believe the snake oil a combination of DB, ESB and SOA will deliver anything anywhere, but how do you know what's where. BTW I'm not interested at the WSDL level, I'm thinking of a tool that the users/BA community would populate and use. A combination of SOA and Database is now the bedrock of most applications, however what used to be called Data Dictionaries, and would now be Service Catalogues? or MetaData repositories still seem to live in purely DataCentric world.

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• Converting ASP.NET MVC to n-Tiered Architecture

  - by Jeff

  I just built an application using ASP.NET MVC. The programmers at my company want to build all future modules using n-Tiered (Presentation Layer, Business Logic Layer, Data Access Layer) architecture. I am not the programmer and need to know why this makes sense? Do I have to completely rewrite the entire code or can it be converted? We are building an HRIS system with Business Intelligence. Somebody please explain why or why not this approach does or does not make sense.

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• jquery $.post returned data from php is empty

  - by vee

  hi, i'm using this code to post to a php page: var qreq = ".....myurl.php"; $.post(qreq, function(data){alert(data);}); in my PHP file i have this: ...... $prevtopic = $row["topic_id"]; echo $prevtopic; the alert comes up, but is blank. for some reason data is empty even though i'm echoing from the PHP file. i also tried just echoing "hi" but that didn't work either. what am i doing wrong? thanks.

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• Buy or build tool for Data Reporting ?

  - by Manoj

  We have been asked to provide a data reporting solution. The followng are the requirements: i. The client has a lot of data which is generated everyday as an outcome of the tests they run. These tests are run at several sites and they get automatically backed up into a central server. ii. They already have perl scripts which post process them and generates excel based reports. iii. They need a web based interface for comparing those reports and they need to mark and track issues which might be present in those data. I am confused if we should build our own tool for this or we should go for already exiting tool(any suggestions?). Can you please provide supportive arguments for the decision that you would suggest?

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• Unit Testing User Interface. What is an effective way ?

  - by pierocampanelli

  I have an accounting & payroll client/server application where there are several input form with complex data validation rules. I am finding an effective way to perform unit testing of user interface. For complex validation rules I mean: "Disable button X if I Insert a value in textfield Y" "Enable a combobox if I insert a value in a textfield" ...... ...... Most promising pattern i have found is suggested by M. Fowler (http://martinfowler.com/eaaDev/ModelViewPresenter.html). Have you any experience about Unit Testing of User Interface? As technology stack I am using: .NET 3.5 & Windows Forms Widget Library.

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• IE8 + Jquery ajax call giving parsererror from dJango : for json data which seems valid in Firefox

  - by PlanetUnknown

  The ajax call works fine in FF. the data returned is in JSON here is an example from FF firebug - {"noProfiles": "No profiles have been created, lets start now !"} When I try to print the error in IE8 (& in compatibility modes as well), it says "parsererror". But the output seems to be valid JSON. Here is the ajax function call I'm making. Any pointers would be great ! $.ajax({ type: "GET", url: "/get_all_profile_details/", data: "", dataType: "json", beforeSend: function() {alert("before send called");}, success: function(jsonData) { alert("data received"); }, error: function(xhr, txt, err){ alert("xhr: " + xhr + "\n textStatus: " + txt + "\n errorThrown: " + err); } }); The alerts in the error function above give - xhr:<blank> textstatus:parsererror errorThrown: undefined Any pointers would be great ! Note : jquery : 1.3.2

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• MySQL load data null values

  - by SP1

  Hello, I have a file that can contain from 3 to 4 columns of numerical values which are separated by comma. Empty fields are defined with the exception when they are at the end of the row: 1,2,3,4,5 1,2,3,,5 1,2,3 The following table was created in MySQL: +-------+--------+------+-----+---------+-------+ | Field | Type | Null | Key | Default | Extra | +-------+--------+------+-----+---------+-------+ | one | int(1) | YES | | NULL | | | two | int(1) | YES | | NULL | | | three | int(1) | YES | | NULL | | | four | int(1) | YES | | NULL | | | five | int(1) | YES | | NULL | | +-------+--------+------+-----+---------+-------+ I am trying to load the data using MySQL LOAD command: load data infile '/tmp/testdata.txt' into table moo fields terminated by "," lines terminated by "\n"; The resulting table: +------+------+-------+------+------+ | one | two | three | four | five | +------+------+-------+------+------+ | 1 | 2 | 3 | 4 | 5 | | 1 | 2 | 3 | 0 | 0 | | 1 | 2 | 3 | NULL | NULL | +------+------+-------+------+------+ The problem lies with the fact that when a field is empty in the raw data and is not defined, MySQL for some reason does not use the columns default value (which is NULL) and uses zero. NULL is used correctly when the field is missing alltogether. Unfortunately, I have to be able to distinguish between NULL and 0 at this stage so any help would be appreciated. Thanks S.

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• Correct model for a database with a table for each user.

  - by BAH

  Kinda stuck here... I have an application with lets say 5000 rows of data per user and was wondering if it was right or wrong to do it this way: On user account creation a new table is created (UserData_[UserID]) or should I just have 1 table for userdata and have everything in there with a column for userid? The reason I am stuck at the moment is that it seems NHibernate isn't able to be mapped to dynamic table names without creating another ISessionFactory which has alot of overhead AFAIK. Any help would be greatly appreciated. Thanks.

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• MySQL Insert Data Question

  - by Nano HE

  Hi, assume I already created a table in MySQL as below CREATE TABLE IF NOT EXISTS `sales` ( `id` smallint(5) unsigned NOT NULL auto_increment, `client_id` smallint(5) unsigned NOT NULL, `order_time` timestamp NOT NULL default CURRENT_TIMESTAMP on update CURRENT_TIMESTAMP, `sub_total` decimal(8,2) NOT NULL, `shipping_cost` decimal(8,2) NOT NULL, `total_cost` decimal(8,2) NOT NULL, PRIMARY KEY (`id`) ) ENGINE=MyISAM DEFAULT CHARSET=latin1 AUTO_INCREMENT=9 ; -- -- Dumping data for table `sales` -- If I added a new field must_fill for the current table. `must_fill` tinyint(1) unsigned NOT NULL, User can insert less than the number of fiels items to the table defaultly, just as the script of below. INSERT INTO `sales` (`id`, `client_id`, `order_time`, `sub_total`, `shipping_cost`, `total_cost`) VALUES (8, 12312, '2007-12-19 01:30:45', 10.75, 3.00, 13.75); It's fine. But How can I configure the field (must_fill) to a MUST INCLUDE Data field when user plan to insert into new data. BTW, The code will be integrated in PHP script.

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• How to validate data for a Rest Service with symfony

  - by Nicolas V.

  For example imagine I've a rest service, this service takes two parameters : phone number text The goal is to send the message via a sms gateway. I've a class Message which has two properties destinationNumber and textMessage. Before calling the gateway, I want to validate the data received by the rest service. I've two questions relatives to how to validate the data : Where should I put the validation rules ? in the model or in the controller How should I use the sfValidator* classes from Symfony to validate the data (ie. where's the documentation for using sfValidator or where can I find some examples) Any help would be appreciated.

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• "Mail merge"-like functionality in Dreamweaver, or in any other web editing tool?

  - by Chris Farmer

  I have inherited several related, low-traffic web sites to manage and edit. These sites are implemented with static html, and they've accrued lots of stray tags and other cruft. I want to try to clean these up and migrate them to some common page template framework to simplify design and data changes and improve overall consistency. The pages will change on the timescale of weeks, and since the current web hosting plan does not support any dynamic server technologies, I was hoping to just use Dreamweaver or some other tool to merge my content data with some templating structure. I'd like to do content updates every several days and then run the content back through my templates, resulting in new static html that I can upload to the host. Do any tools support this kind of poor-man's data-driven web application? Are there better ways to approach this problem, aside from moving to a new hosting plan and using ASP.NET or PHP?

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• RSA encrypted data block size

  - by calccrypto

  how do you store an rsa encrypted data block? the output might be significantly greater than the original input data block size, and i dont think people waste memory by padding bucket loads of 0s in front of each data block. besides, how would they be removed? or is each block stored on new lines within the file? if that is the case, how would you tell the difference between legitimate new line and a '\n' char written into the file? what am i missing? im writing the "write to file" part in python, so maybe its one of the differences between: open(file,'w') open(file,'w+b') open(file,'wb') that i dont know. or is it something else?

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• Architecture of a single-page JavaScript web application?

  - by fig-gnuton

  How should a complex single-page JS web application be structured on the client-side? Specifically I'm curious about how to cleanly structure the application in terms of its model objects, UI components, any controllers, and objects handling server persistence. MVC seemed like a fit at first. But with UI components nested at various depths (each with their own way of acting on/reacting to model data, and each generating events which they themselves may or may not handle directly), it doesn't seem like MVC can be cleanly applied. (But please correct me if that's not the case.) -- (This question resulted in two suggestions of using ajax, which is obviously needed for anything other than the most trivial one-page app.)

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• DI with disposable objects

  - by sunnychaganty

  Suppose my repository class looks like this: class myRepository : IDisposable{ private DataContext _context; public myRepository(DataContext context){ _context = context; } public void Dispose(){ // to do: implement dispose of DataContext } } now, I am using Unity to control the lifetime of my repository & the data context & configured the lifetimes as: DataContext - singleton myRepository - create a new instance each time Does this mean that I should not be implementing the IDisposable on the repository to clean up the DataContext? Any guidance on such items?

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• How Do You Parse Column Data ?

  - by discwiz

  I am trying to parse a file generated by LGA Tracon that lists the position data for aircraft over a given time frame. The data of interest starts with TRACKING DATA and ends with SST and there are thousands of entries per file. The system generating the file, Common ARTS, is very rigid in its formatting and we can expect the column spacing to be consistent. Any help would be greatly appreciated. Thanks, Here is an image to preserve the exact formatting Here is a reduced text file. link text

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• Send post data while opening SSE connection

  - by Prosto Trader

  I'm trying to establish SSE connection and do some long-taking actions on server-side, informing user about how it goes through SSE events. Actually, I don't understand how would I send some data along with new connection. I have to combine regular ajax with new EventSource or there is a way to transfer post data inside that event? Here is what I have so far, and I need to send pretty big JSON with the request. Is it possible or the only way to send data is GET? var source = new EventSource('/terminal/ajax-put-packet-trade-order/');

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• JQuery Validation using Remote posts empty data to webservice

  - by user319721

  I'm using the JQuery Validation plugin. I'm using the remote option to make a call to my webservice to check if a company name exists. The webservice only accepts JSON data. I pass the data to the webservice from the Company Input Field in my Form as follows: data: "{'company': '" + $('#Company').val() + "'}" But this always returns a blank value for company so the response is {'company':''} i.e. correct JSON but missing the Company Input Field value. Can anyone shed some light on why I always get a blank value here? Thanks for the help, Ciaran

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