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• iPhone , core data, whether NSManagedObject use lazy load mechanism when it was create ?

  - by Robin

  Hi, all, I have use core data in app, I have definite a class that most like as follows: @interface Master : NSManagedObject { } @property (nonatomic, retain) NSSet* Details; .... the entity Master contains a property 'Details' that is relate to another table, this is typical Master-Details relationship, I trace the app , but I find a issue that the property 'Details' value was construct even it never be invoked ..... but I consider that the core data 'should' use some lazy mechanism to improve performance, or maybe I miss some configure step ? because the Master entity contains at least five 'Child' table properties , I have to consider this problem before use the core data .... any help ? thanks for your time!

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• Stored Procedure or calculations via IQueryable?

  - by Shawn Mclean

  This is a question that is based on choosing performance over design practices. If I have a method that will be executed many times a second; public static IQueryable<IPerson> InRadius(this IQueryable<IPerson> query, Coordinate center, double radius) { return (from u in query where CallHeavyMathFormula(u, center, radius) select u); } This extension method for IQueryable generates a SQL that does some heavy maths calculation (Cosine, Sine, etc). This would mean the application sends 1-2KB of sql to the server per call. I've heard of placing all application logic, in your application. I also would like to change to a database such as azure or one of those scalable databases in the future. How do I handle something like this? Should I leave it as it is now or write stored procedures? How do applications like twitter or facebook do it?

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• how to pass in a reference to a string in javascript?

  - by ijjo

  maybe a closure is my solution? not exactly sure how to pull it off though. the code is set up like so: var globalVar = ''; var globalVar2 = ''; function func() { if (condition) func2(globalVar) else func2(globalVar2) } in func2() i cache some HTML in a main container into the appropriate global variable that i pass to it. basically i have a main container that holds different pages depending on what tab they choose. for performance i want to cache the page into global vars so i need to know what tab is active to figure out which global var to assign the html to.

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• Measuring the time to create and destroy a simple object

  - by portoalet

  From Effective Java 2nd Edition Item 7: Avoid Finalizers "Oh, and one more thing: there is a severe performance penalty for using finalizers. On my machine, the time to create and destroy a simple object is about 5.6 ns. Adding a finalizer increases the time to 2,400 ns. In other words, it is about 430 times slower to create and destroy objects with finalizers." How can one measure the time to create and destroy an object? Do you just do: long start = System.nanoTime(); SimpleObject simpleObj = new SimpleObject(); simpleObj.finalize(); long end = System.nanoTime(); long time = end - start;

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• Ternary operators and variable reassignment in PHP

  - by TomcatExodus

  I've perused the questions on ternary operators vs. if/else structures, and while I understand that under normal circumstances there is no performance loss/gain in using ternary operators over if/else structures, I've not seen any mention of this situation. Language specific to PHP (but any language agnostic details are welcome) does the interpreter reassign values in situations like this: $foo = 'bar' $foo = strlen($foo) > 3 ? substr($foo, 0, 3) : $foo; Since this would evaluate to $foo = $foo; is this inefficient, or does the interpreter simply overlook/discard this evaluation? On a side note, what about: !defined('SECURE') ? exit : null;

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• Is there any advantage to having more than 16gb ram on a Windows Dev machine?

  - by Robert Kozak

  Assuming a machine (Dual Quad Core Xeon (2.26GHz) with 24GB RAM) running Windows Server 2008 and Hyper-V. How many VMs can I expect to run at the same time with good performance. Is this overkill? Can you really have too much RAM? Assuming 2GB per VM thats around 16GB for the VMs with 8GB left over for the Main OS and Hyper-V. Sound about right? Edit: Tried to make the question sound less like bragging. Was never my intention. Its a hard question to write.

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• (NOT) NULL for NVARCHAR columns

  - by Anders Abel

  Allowing NULL values on a column is normally done to allow the absense of a value to be represented. When using NVARCHAR there is aldready a possibility to have an empty string, without setting the column to NULL. In most cases I cannot see a semantical difference between an NVARCHAR with an empty string and a NULL value for such a column. Setting the column as NOT NULL saves me from having to deal with the possibility of NULL values in the code and it feels better to not have to different representations of "no value" (NULL or an empty string). Will I run into any other problems by setting my NVARCHAR columns to NOT NULL. Performance? Storage size? Anything I've overlooked on the usage of the values in the client code?

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• Background upload in PHP

  - by Robijntje007

  I am working with a form that allows me to upload files via a local folder and FTP. So I want to move files over ftp (which already works) Because of performance reasons I chose this process to run in the background so I use nfcftpput (linux) In CLI the following command works perfectly: ncftpput-b-u name -p password -P 1980 127.0.0.1 /upload/ /home/Downloads/upload.zip (Knowing that the b-parameter triggers background process) But if I run it via PHP it does not work (without the-b parameter it does) PHP code: $cmd = "ncftpput -b -u name -p password -P 1980 127.0.0.1 /upload/ /home/Downloads/upload.zip"; $return = exec($cmd);

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• Giving Users an Option Between UDP & TCP?

  - by cam

  After studying TCP/UDP difference all week, I just can't decide which to use. I have to send a large amount of constant sensor data, while at the same time sending important data that can't be lost. This made a perfect split for me to use both, then I read a paper (http://www.isoc.org/INET97/proceedings/F3/F3_1.HTM) that says using both causes packet/performance loss in the other. Is there any issue presented if I allow the user to choose which protocol to use (if I program both server side) instead of choosing myself? Are there any disadvantages to this? The only other solution I came up with is to use UDP, and if there seems to be too great of loss of packets, switch to TCP (client-side).

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• What are some Servlet Container pros and cons for a Solr installation?

  - by danieltalsky

  The SolrInstall wiki page lists seven different server / Servlet Containers compatible with Solr: Tomcat Jetty Resin JBoss WebSphere Weblogic Glassfish I'm sure that "best" is subjective, so I'll just say my criteria are: easiest to set up, best for search performance with a smallish, infrequently-updated dataset, and with the fewest number of gotchas. Jetty and Tomcat both have apt-get solr packages, so they're clearly the frontrunners for some. Jetty is used in the demo install, but there's some notes that Jetty has some difficulties handling Unicode in some cases. Tomcat is a common choice but my understanding is that it's not as lightweight and has a lot of features not needed by Solr. Is it worth considering any of the others? Are there some important pro's and cons I should be aware of?

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• Can I tell Borland C++ Builder to copy a file somewhere else after it is built?

  - by MrVimes

  I have two computers. One is intended to be left 'free' for high-performance activities (such as playing games) The other is my 'all purpose' computer where I install all the apps I use for creating things, and so on. On the second computer I use Codegear C++ Builder to work on an app that I use on the first computer. If I have BCB compile to comp 1 it is hopeless. It becomes unresponsive. It compiles locally very quickly. So what I do is compile locally and then copy the exe to the other machine. Well, I'm all for streamlining processes, so I want a way to compile on PC2 and use on PC1 without any intermediate steps. So is it possible to have BCB do the compiling on PC2 and create a local exe file, then copy the file to PC 1?

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• How much faster is a database running in RAM?

  - by orokusaki

  I"m looking to run PostgreSQL in RAM for performance enhancement. The database isn't more than 1GB and shouldn't ever grow to more than 5GB. Is it worth doing? Are there any benchmarks out there? Is it buggy? My second major concern is: How easy is it to back things up when it's running purely in RAM. Is this just like using RAM as tier 1 HD, or is it much more complicated?

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• Should I Split Tables Relevant to X Module Into Different DB? Mysql

  - by Michael Robinson

  I've inherited a rather large and somewhat messy codebase, and have been tasked with making it faster, less noodly and generally better. Currently we use one big database to hold all data for all aspects of the site. As we need to plan for significant growth in the future, I'm considering splitting tables relevant to specific sections of the site into different databases, so if/when one gets too large for one server I can more easily migrate some user data to different mysql servers while retaining overall integrity. I would still need to use joins on some tables across the new databases. Is this a normal thing to do? Would I incur a performance hit because of this?

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• Is a PHP-only "cache engine" ever worth it?

  - by adsads

  I wrote a rather small skeleton for my web apps and thought that I would also add a small cache for it. It is rather simple: If the current page exists as a file in the cache and the file isn't too old, read it out and exit instead of rebuilding the page If the current page isn't cached/outdated recalc the page and save it However, the bad thing about it is: My performance tests with a page that receives 40 relatively long posts via a MySQL query said that with using the cache, it took even longer to handle a single request (1000 tests each) How can that happen? Should I just remove the complete raw-PHP cache and relieve on the availability of some PHP cache like memcached or so?

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• Python 3-compatibe HTML to text converter preserving basic structure under permissive licence?

  - by hawk64

  I am looking for a relatively simple HTML to text converter which displays links and works on strings. So far I have tried lynx but performance is too bad, html2text which gives weird and verbose markdown output and is under GPLv3 which is too restrictive for my (BSD-licensed) project, http://effbot.org/librarybook/formatter-example-3.py using htmllib.HTMLParser with formatter.AbstractFormatter and a custom writer, however htmllib.HTMLParser is drpeceated and has been removed from Python 3. So is there any simple, performant, Python 3-compatible HTML to text converter under a permissive license such as MIT/BSD/Apache and the like? Edit: I dont just need something to strip HTML-Tags but also to preserve the basic structure of the HTML, that is output that somewhat resembles that of Lynx.

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• C++ get method - returning by value or by reference

  - by HardCoder1986

  Hello! I've go a very simple question, but unfortunately I can't figure the answer myself. Suppose I've got some data structure that holds settings and acts like a settings map. I have a GetValue(const std::string& name) method, that returns the corresponding value. Now I'm trying to figure out - what kind of return-value approach would be better. The obvious one means making my method act like std::string GetValue(const std::string& name) and return a copy of the object and rely on RVO in performance meanings. The other one would mean making two methods std::string& GetValue(...) const std::string& GetValue(...) const which generally means duplicating code or using some evil constant casts to use one of these routines twice. #Q What would be your choice in this kind of situation and why?

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• Codeigniter - Is it ok to add functionality to the constructor in controllers?

  - by Irro

  I'm making a project where I want the user to search for shops in different cities and would like the url to be like this: domain/shop/city/name. So I created a controller in codeigniter called Shop. But I cant create a city function since the city part of the url changes dependent on city name. One easy way to do it would be to add a function called "search" and add the functionality there but then I get url's like: domain/shop/search/city/name which I really would like to avoid. So my question is if it's ok to add my functionality directly into the constructor to avoid that extra "search" part in the url? I'm afraid that there might be some performance tricks involved that potentially keeps the class in memory so the constructor will not be called every time.

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• when to use StringBuilder in java

  - by kostja

  It is supposed to be generally preferable to use a StringBuilder for String concatenation in Java. Is it always the case? What i mean is : Is the overhead of creating a StringBuilder object, calling the append() method and finally toString() smaller then concatenating existing Strings with + for 2 Strings already or is it only advisable for more Strings? If there is such a threshold, what does it depend on (the String length i suppose, but in which way)? And finally - would you trade the readability and conciseness of the + concatenation for the performance of the StringBuilder in smaller cases like 2, 3, 4 Strings?

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• Huge framerate difference between Test and Publish movie in Flash?

  - by Glacius

  Simply put, I am making a flash midi player. I am using ENTER_FRAME for my timings. I set the framerate to 100 to ensure that the timing of each note in milliseconds is accurate. When I test the movie with CTRL + ENTER it works fine. When I publish it and open it in a browser (tested both IE and Chrome), it suddenly plays back a lot slower. I don't think it's a performance issue, since the code is very simple. If this slowdown is consistent then I can perhaps work with it so that the playback speed will be correct. Do browsers make the framerate slower or do they implement a framerate cap of some sort? What is going on?

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• ASP.NET Website or Web service?

  - by fireBand

  Hi, I am trying to implement a service to download a image file. The code does nothing but upload a file to the response with each client request. There are no SOAP messages involved but I am planning to implement it as ASP.NET web service. It can also be implement as ASP.NET website but since it has no view (forms, html etc) I planned to implement a web-service. Is this a better approach? Does ASP.NET Website offer better performance that a Web-service? Which one would be better is this situation? Thanks in advance.

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• How to get some randomized concats based on 2 columns from 1 table?

  - by Nils Riedemann

  Hey folks, i have a large user Database (13k+), and for some reason i need to create random names. The users table has "first_name" and "last_name". Now i want to have 10 concats of full_name and last_name of two completely random rows. Is that even possible with SQL? My other idea was just to create a full_names and last_names table … but that would'nt be as much challenging. Oh, and it should not take up too much performance :) (so order by rand() is not an option ;))

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• Advantages of using WCF to work with Sharepoint Services WSS3.0?

  - by val

  Hi folks, what is your opinion or better off your practical experience using WCF to work with WSS instead of SP web services? I am writing some custom library for our software to store and retrieve files from WSS document libraries using sharepoint web services. I am not entirely happy with the performance of the sp web services - a bit too slow in many cases. Now, microsoft claims a significant improvements in WCF over remoting and I am looking into a good way to use WCF for my file services. Any suggestions or ideas? Maybe a good source of coding practices or blogs? Thanks a lot, Val

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• Should I use "id" or "unique username"?

  - by roa3

  I am using PHP, AS3 and mysql. I have a website. A flash(as3) website. The flash website store the members' information in mysql database through php. In "members" table, i have "id" as the primary key and "username" as a unique field. Now my situation is: When flash want to display a member's profile. My questions: Should Flash pass the member "ID" or "username" to php to process the mysql query? Is there any different passing the "id" or "username"? Which one is more secure? Which one you recommend? I would like to optimize my website in terms of security and performance.

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• IF/ELSE makes stored procedure not return a result set

  - by Brendan Long

  I have a stored procedure that needs to return something from one of two databases: IF @x = 1 SELECT @y FROM Table_A ELSE IF @x = 2 SELECT @y FROM Table_B Either SELECT alone will return what I want, but adding the IF/ELSE makes it stop returning anything. I tried: IF @x = 1 RETURN SELECT @y FROM Table_A ELSE IF @x = 2 RETURN SELECT @y FROM Table_B But that causes a syntax error. The two options I see are both horrible: Do a UNION and make sure that only one side has any results: SELECT @y FROM Table_A WHERE @x = 1 UNION SELECT @y FROM Table_B WHERE @x = 2 Create a temporary table to store one row in, and create and delete it every time I run this procedure (lots). Neither solution is elegant, and I assume they would both be horrible for performance (unless MS SQL is smart enough not to search the tables when the WHERE class is always false). Is there anything else I can do? Is option 1 not as bad as I think?

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• Large static arrays are slowing down class load, need a better/faster lookup method

  - by Visualize

  I have a class with a couple static arrays: an int[] with 17,720 elements a string[] with 17,720 elements I noticed when I first access this class it takes almost 2 seconds to initialize, which causes a pause in the GUI that's accessing it. Specifically, it's a lookup for Unicode character names. The first array is an index into the second array. static readonly int[] NAME_INDEX = { 0x0000, 0x0001, 0x0005, 0x002C, 0x003B, ... static readonly string[] NAMES = { "Exclamation Mark", "Digit Three", "Semicolon", "Question Mark", ... The following code is how the arrays are used (given a character code). [Note: This code isn't a performance problem] int nameIndex = Array.BinarySearch<int>(NAME_INDEX, code); if (nameIndex > 0) { return NAMES[nameIndex]; } I guess I'm looking at other options on how to structure the data so that 1) The class is quickly loaded, and 2) I can quickly get the "name" for a given character code. Should I not be storing all these thousands of elements in static arrays?

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