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  • Save user favorites

    - by Radu D
    Hi, In my application I need to display items to the user. He can mark some items as favorites. I need to display those differently. How can I save the favorites on the user's computer? I need something like a config entry ... but I need to change that as the user add/remove the favorites. Do you think that I should save that in registry ... or on the disk in a separate file? Does .net offers some support for such situations? Thanks, Radu

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  • Implementing Tagging using Core Data on the iPhone

    - by Jonathan Penn
    I have an application that uses CoreData and I'm trying to figure out the best way to implement tagging and filtering by tag. For my purposes, if I was doing this in raw SQLite I would only need three tables, tags, item_tags and of course my items table. Then filtering would be as simple as joining between the three tables where only items are related to the given tags. Quite straightforward. But, is there a way to do this in CoreData and utilizing NSFetchedResultsController? It doesn't seem that NSPredicate give you the ability to filter through joins. NSPredicate's aren't full SQL anyway so I'm probably barking up the wrong tree there. I'm trying to avoid reimplementing my app using SQLite without CoreData since I'm enjoying the performance CoreData gives me in other areas. Yes, I did consider (and built a test implementation) diving into the raw SQLite that CoreData generates, but that's not future proof and I want to avoid that, too. Has anyone else tried to tackle tagging/filtering with CoreData in a UITableView with NSFetchedResultsController

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  • C++ Urban Myths

    - by Neil Butterworth
    I'm starting to write an article on what I'm calling "C++ Urban Myths" - that is, ideas and conceptions about C++ that are common but have no actual roots in reality. Some that I've come up with so far are: TR1 is part of standard C++ TR1 (technical Report #1) proposed a whole bunch of changes to C++. Unfortunately, it was never accepted. It is faster to use iterators to access a vector than operator[] Or vice versa. All tests I've carried out indicate the two are nearly identical in performance. The C++ Standard contains something called the STL It doesn't - neither "STL" nor "Standard Template Library" appear in the Standard. I'm wondering if the SO C++ community can come up with any better ones? Ideally, they should be expressible in a single sentence, and not involve any code. Edit: I guess I didn't make it clear enough that I was interested in myths believed by C++ developers, not misconceptions held by non-C++users. Oh well...

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  • Best method of Zend Framework caching

    - by iamthejeff
    I have a blog built using Zend Framework, which I realize might be a bit overkill for a blog alone, but I am planning on adding other features in the future. Nevertheless, I've noticed pages could be a little speedier. I've done a basic caching method that basically captures everything in index.php (Core frontend and File backend), which works great, but unfortunately it also prevents dynamic page contents from updating (messages like "this was posted 5 minutes ago", etc) until the cache period expires. So my question is what would be the best method of caching to improve performance? I am doing fairly basic queries which are mostly simple selects, not many joins or anything fancy (using Zend_Db_Table), and even on a small database page loads are a little sluggish. Is it worth it to cache queries or should I focus my time elsewhere?

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  • Interview Question: .Any() vs if (.Length > 0) for testing if a collection has elements

    - by Chris
    In a recent interview I was asked what the difference between .Any() and .Length > 0 was and why I would use either when testing to see if a collection had elements. This threw me a little as it seems a little obvious but feel I may be missing something. I suggested that you use .Length when you simply need to know that a collection has elements and .Any() when you wish to filter the results. Presumably .Any() takes a performance hit too as it has to do a loop / query internally.

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  • Optimising (My)SQL Query

    - by Simon
    I usually use ORM instead of SQL and I am slightly out of touch on the different JOINs... SELECT `order_invoice`.*, `client`.*, `order_product`.*, SUM(product.cost) as net FROM `order_invoice` LEFT JOIN `client` ON order_invoice.client_id = client.client_id LEFT JOIN `order_product` ON order_invoice.invoice_id = order_product.invoice_id LEFT JOIN `product` ON order_product.product_id = product.product_id WHERE (order_invoice.date_created >= '2009-01-01') AND (order_invoice.date_created <= '2009-02-01') GROUP BY `order_invoice`.`invoice_id` The tables/ columns are logically names... it's an shop type application... the query works... it's just very very slow... I use the Zend Framework and would usually use Zend_Db_Table_Row::find(Parent|Dependent)Row(set)('TableClass') but I have to make lots of joins and I thought it'll improve performance by doing it all in one query instead of hundreds... Can I improve the above query by using more appropriate JOINs or a different implementation? Many thanks.

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  • Keeping track of dirty blocks on a block device

    - by mikeY
    I'm looking for a way to keep track of what blocks on a block device are modified after a point in time. How I eventually want to use this for is to keep two 2TB disks in sync, one which only comes online (connected through USB) once a month. Without knowing what blocks have been modified, I have to go through the whole 2TB every time. I'm using a recent GNU/Linux OS and have C and Python experience. I'm hoping to avoid writing kernel level code as I don't have any experience in that area whatsoever. My current theory is that there should be some hooks somewhere where my code can get called when a disk flush is performed. Any ideas?

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  • Multivalue Mysql Inserts using HibernateTemplate

    - by Langali
    I am using Spring HibernateTemplate and need to insert hundreds of records into a mysql database every second. Not sure what is the most performant way of doing it, but I am trying to see how the multi value mysql inserts do using hibernate. String query = "insert into user(age, name, birth_date) values(24, 'Joe', '2010-05-19 14:33:14'), (25, 'Joe1', '2010-05-19 14:33:14')" getHibernateTemplate().execute(new HibernateCallback(){ public Object doInHibernate(Session session) throws HibernateException, SQLException { return session.createSQLQuery(query).executeUpdate(); } }); But I get this error: 'could not execute native bulk manipulation query.' Please check your query ..... Any idea of I can use a multi value mysql insert using Hibernate? or is my query incorrect? Any other ways that I can improve the performance? I did try the saveOrUpdateAll() method, and that wasn't good enough!

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  • Rails ActiveRecord - How to set association save order

    - by Altonymous
    I have a weird relationship that needs to be maintained for legacy processes. I'm trying to figure out how to create the relationship given the new model association. New Relationship Setup Machine has_many MachineReadings has_many Disks has_many DiskReadings Old Relationship Setup Machine has_many MachineReadings has_many DiskReadings has_many Disks The problem is data will come in on the Machine model as nested attributes using the new relationship setup. I need to update the machine_reading_id in the DiskReading model so the old association can continue to be used. I tried doing this via an after_save hook that would traverse back up to the machine and then down to the readings to get the machine_reading.id so I could populate the DiskReading model. However, the associations aren't being saved in the order I would expect. They are saving the Disks & DiskReadings before saving the MachineReadings. So when I go after the machine_reading.id it hasn't been written and thus I am unable to get access to it. For example: #machine_disk_reading.rb after_save :build_old_relationship def build_old_relationship self.machine_reading_id = self.disk.machine.readings.find_by_date_time(self.date_time).id end

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  • Designing a table to store EXIF data

    - by rafale
    I'm looking to get the best performance out of querying a table containing EXIF data. The queries in question will only search the EXIF data for the specified strings and return the row index on a match. With that said, would it better to store the EXIF data in a table with separate columns for each of the tags, or would storing all of the tags in a single column as one long delimited string suit me just as well? There are around 115 EXIF tags I'll be storing, and each record would be around 1500 to 2000 chars in length if concatenated into a single string.

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  • Conceptually, how does replay work in a game?

    - by SnOrfus
    I was kind of curious as to how replay might be implemented in a game. Initially, I thought that there would be just a command list of every player/ai action that was taken in the game, and it then 're-plays' the game and lets the engine render as usual. However, I have looked at replays in FPS/RTS games, and upon careful inspection even things like the particles and graphical/audible glitches are consistent (and those glitches are generally *in*consistent). So How does this happen. In fixed camera angle games I though it might just write every frame of the whole scene to a stream that gets stored and then just replays the stream back, but that doesn't seem like enough for games that allow you to pause and move the camera around. You'd have to store the locations of everything in the scene at all points in time (No?). So for things like particles, that's a lot of data to push which seems like a significant draw on the game's performance whilst playing.

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  • Detecting and reloading updated application parameters at runtime

    - by VeeKayBee
    I am working on an ASP.NET web application(using .NET 4.5 and C#).The application deals with lot of units (for measuring like KG,Litre,KM etc). So based on the selected unit we have to implement some allowed range.This values can be configured without much effort. We identified two solutions for this Keeping a configuration xml. Suppose the values in xml, does it requires an iisreset or any other thing which can take the site down for some time, if we are changing the xml file to change some validation. Keeping in Db, then use SQL dependency caching. So an update to DB can reflect the caching values.SO i believe if we change the values, it will update the cache. How much complex is this and does it effect the performance ? It will be great helpful, if we have some other method to achieve this. Thanks in advance.

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  • storing huge amount of records into classic asp cache object is SLOW

    - by aspm
    we have some nasty legacy asp that is performing like a dog and i narrowed it down to because we are trying to store 15K+ records into the application cache object. but that's not the killer. before it stores it, it converts the ADO stream to XML then stores it. this conversion of the huge record set to XML spikes the CPU and causes all kinds of havoc on users when it's happening. and unfortunately we do this XML conversion to read the cache a lot, causing site wide performance problems. i don't have the resources to convert everything to .net. so that's out. but i need to obviously use caching, but int his case the caching is hurting instead of helping. is there a more effecient way to store this data instead of doing this xml conversion to/from every time we read/update the cache?

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  • GetHashCode Method reliability in Silverlight/WP7.1

    - by abhinav
    I am attempting to hash and keep(the hash) an object of type IEnumerable<anotherobject> which has about a 1000 entries. I'll be generating another such object, but this time I'd like to check for any changes in the values of the entries using the hash codes of the two objects. Basically, I was wondering if GetHashCode() is apt for this, both from a performance perspective and reliability perspective (getting different values for different object values and same values for same object values, always). If I have to override it, what would be a good way to do so, does it always depend on the type of anotherobject and what Equals means when comparing two anotherobjects? Is there a generic way to do it? This concern is because my object can be quite big.

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  • When does it make sense to use a map?

    - by kiwicptn
    I am trying to round up cases when it makes sense to use a map (set of key-value entries). So far I have two categories (see below). Assuming more exist, what are they? Please limit each answer to one unique category and put up an example. Property values (like a bean) age -> 30 sex -> male loc -> calgary Presence, with O(1) performance peter -> 1 john -> 1 paul -> 1

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  • fast on-demand c++ compilation [closed]

    - by Amit Prakash
    I'm looking at the possibility of building a system where when a query hits the server, we turn the query into c++ code, compile it as shared object and the run the code. The time for compilation itself needs to be small for it to be worthwhile. My code can generate the corresponding c++ code but if I have to write it out on disk and then invoke gcc to get a .so file and then run it, it does not seem to be worth it. Are there ways in which I can get a small snippet of code to compile and be ready as a share object fast (can have a significant start up time before the queries arrive). If such a tool has a permissive license thats a further plus. Edit: I have a very restrictive query language that the users can use so the security threat is not relevant. My own code translates the query into c++ code. The answer mentioning clang is perfect.

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  • CakePHP repeats same queries

    - by Rytis
    I have a model structure: Category hasMany Product hasMany Stockitem belongsTo Warehouse, Manufacturer. I fetch data with this code, using containable to be able to filter deeper in the associated models: $this->Category->find('all', array( 'conditions' => array('Category.id' => $category_id), 'contain' => array( 'Product' => array( 'Stockitem' => array( 'conditions' => array('Stockitem.warehouse_id' => $warehouse_id), 'Warehouse', 'Manufacturer', ) ) ), ) ); Data structure is returned just fine, however, I get multiple repeating queries like, sometimes hundreds of such queries in a row, based on dataset. SELECT `Warehouse`.`id`, `Warehouse`.`title` FROM `beta_warehouses` AS `Warehouse` WHERE `Warehouse`.`id` = 2 Basically, when building data structure Cake is fetching data from mysql over and over again, for each row. We have datasets of several thousand rows, and I have a feeling that it's going to impact performance. Is it possible to make it cache results and not repeat same queries?

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  • Can I stop ASP.NET from returning 'The resource cannot be found.'?

    - by mackenir
    I have installed an HttpModule into my web app that will handle all requests with a given file extension. I want ASP.NET to handle all requests with the extension, regardless of whether there is an underlying file on disk. So, when I added the extension to the 'Application Extension Mappings', I unchecked the 'Verify that file exists' checkbox. However, this just transfers the file check to ASP.NET rather IIS, so I just get a different error page when requesting URLs with the file extension. Is there a way to preempt this ASP.NET file checking and intercept the requests?

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  • Is there an additional runtime cost for using named parameters?

    - by Jurily
    Consider the following struct: public struct vip { string email; string name; int category; public vip(string email, int category, string name = "") { this.email = email; this.name = name; this.category = category; } } Is there a performance difference between the following two calls? var e = new vip(email: "foo", name: "bar", category: 32); var e = new vip("foo", 32, "bar"); Is there a difference if there are no optional parameters defined?

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  • How do I connect two apps

    - by sevaxx
    I am considering building an app in C++ that will be parsing text from the web and create some statistical results. These results I want to be fed in an external app in real time. The external app (to whose code I have no access, but can ask for a - paid - custom made addition) will then need some code to read and use these results. I am wondering what would be the best way to interconnect the two apps, in terms of speed and ease of implementation. I am considering : disk I/O (slow) a Windows service a DLL a web service a web page Perhaps I am missing a better solution ? Thank you.

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  • PostgreSQL: How to index all foreign keys?

    - by biggusjimmus
    I am working with a large PostgreSQL database, and I are trying to tune it to get more performance. Our queries and updates seem to be doing a lot of lookups using foreign keys. What I would like is a relatively simple way to add Indexes to all of our foreign keys without having to go through every table (~140) and doing it manually. In researching this, I've come to find that there is no way to have Postgres do this for you automatically (like MySQL does), but I would be happy to hear otherwise there, too.

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  • iPhone. How to intercept system dialogs?

    - by Sjakelien
    My app offers the user the opportunity to put an event in his native calendar. For that, I refer to an online webcal:// URL. Since the underlying .ics file is quite big (containing quite a few events), it sometimes (also depending on the network performance)takes a while before the "Do you want to subscribe"-dialog sequence kicks in. I would like to give the user some feedback in the mean time, like a spinner, or a changing graphic, for him to know that something is going to happen. Question: how does my app know, that the "Do you want to subscribe"-dialog has been shown, and that the user has chosen either a Cancel of OK button in that dialog, so I can stop the spinner?

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  • How to transfer large files from desktop to server ( .NET)

    - by rahulchandran
    I am writing a .NET 2.0 based desktop client that will send large files ( well largish under 2GB) to a server. Need to develop the server as well. Server can be on any technology It should be secure so an underlying SSL stream is needed What are my options. Any obvious caveats etc I should be aware of To my mind the simplest solution is to open a tcp\ip connection over SSL to the server and send n packets each of size M bytes and then have the server append the chunks to the file and finally send an EOF packet as well IS this horrible. Will the perf suck on the server with all these disk writes What are any other clever options. I am limited to .NET 2.0 on the client if I did move to a WCF client will it buy be something magical and cool for this scenario Thanks

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  • Storing Instances of Classes in Flex Shared Objects

    - by babyangel86
    Is it possible to store instances of a class in a cookie or in shared objects. Basically in my application I have an object "Diagram" that the user can create. If they hit save, I want to store the current instance as a cookie and allows them to reload it later. Alternatively, I could see about getting them to store the saved version on the hard disk. But even then, all I want to save and retreive is my actionscript object. Is this possible? I've tried storing the object to SharedObject.data.diag, but when I try to retrieve the object from the cookie doing SharedObject.data.diag as Diag returns null.

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  • Is there a more correct type for passing in the file path and file name to a method

    - by Rihan Meij
    Hi What I mean by this question is, when you need to store or pass a URL around, using a string is probably a bad practice, and a better approach would be to use a URI type. However it is so easy to make complex things more complex and bloated. So if I am going to be writing to a file on disk, do I pass it a string, as the file name and file path, or is there a better type that will be better suited to the requirement? This code seems to be clunky, and error prone? I would also need to do a whole bit of checking if it is a valid file name, if the string contains data and the list goes on. private void SaveFile(string fileNameAndPath) { //The normal stuff to save the file }

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