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  • optimize query: get al votes from user's item

    - by Toni Michel Caubet
    hi there! i did it my way because i'm very bad getting results from two tables... Basically, first i get all the id items that correspond to the user, and then i calculate the ratings of each item. But, there is two different types of object item, so i do this 2 times: show you: function votos_usuario($id){ $previa = "SELECT id FROM preguntas WHERE id_usuario = '$id'"; $r_previo = mysql_query($previa); $ids_p = '0, '; while($items_previos = mysql_fetch_array($r_previo)){ $ids_p .= $items_previos['id'].", "; //echo "ids pregunta usuario: ".$items_previos['id']."<br>"; } $ids = substr($ids_p,0,-2); //echo $ids; $consulta = "SELECT valor FROM votos_pregunta WHERE id_pregunta IN ( $ids )"; //echo $consulta; $resultado = mysql_query($consulta); $votos_preguntas = 0; while($voto = mysql_fetch_array($resultado)){ $votos_preguntas = $votos_preguntas + $voto['valor']; } $previa_r = "SELECT id FROM recetas WHERE id_usuario = '$id'"; $r_previo_r = mysql_query($previa_r); $ids_r = '0, '; while($items_previos_r = mysql_fetch_array($r_previo_r)){ $ids_r .= $items_previos_r['id'].", "; //echo "ids pregunta usuario: ".$items_previos['id']."<br>"; } $ids = substr($ids_r,0,-2); $consulta_b = "SELECT valor FROM votos_receta WHERE id_receta IN ( $ids )"; //echo $consulta; $resultado_b = mysql_query($consulta_b); $votos_recetas = 0; while($voto_r = mysql_fetch_array($resultado_b)){ $votos_recetas = $votos_recetas + $voto_r['valor']; } $total = $votos_preguntas + $votos_recetas; return $total; } As you can si this is two much.. O(n^2) Feel like thinking? thanks!

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  • Test assembly code on a mac

    - by happyCoding25
    Hello, A while back I was following some tutorials an assembly. I was running it all on a windows machine, compiling with NASM and then writing the compiled code to a floppy disk, then reboot and try the code. This process was long and time consuming and sadly was not on a mac. When I found out that Xcode for mac installed NASM I immediately tried to compile some code. The code compiled fine. The issue is testing it. On a mac I have no floppy (not like I want to use one) so Im not sure how to test this. I looked in to Q (kju) and found it would only emulate things on an ISO file. So I guess what Im asking is is it possible to install the compiled code on an ISO file for testing? (Note: the code when compiled forms a .bin file) Thanks for any help

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  • iPhone - dequeueReusableCellWithIdentifier usage

    - by Jukurrpa
    Hi, I'm working on a iPhone app which has a pretty large UITableView with data taken from the web, so I'm trying to optimize its creation and usage. I found out that dequeueReusableCellWithIdentifier is pretty useful, but after seeing many source codes using this, I'm wondering if the usage I make of this function is the good one. Here is what people usually do: UITableViewCell* cell = [tableView dequeueReusableCellWithIdentifier:@"Cell"]; if (cell == nil) { cell = [[UITableViewCell alloc] initWithFrame:CGRectZero reuseIdentifier:@"Cell"]; // Add elements to the cell return cell; And here is the way I did it: NSString identifier = [NSString stringWithFormat:@"Cell @d", indexPath.row]: // The cell row UITableViewCell* cell = [tableView dequeueReusableCellWithIdentifier:identifier]; if (cell != nil) return cell; cell = [[UITableViewCell alloc] initWithFrame:CGRectZero reuseIdentifier:identifier]; // Add elements to the cell return cell; The difference is that people use the same identifier for every cell, so dequeuing one only avoids to alloc a new one. For me, the point of queuing was to give each cell a unique identifier, so when the app asks for a cell it already displayed, neither allocation nor element adding have to be done. In fine I don't know which is best, the "common" method ceils the table's memory usage to the exact number of cells it display, whislt the method I use seems to favor speed as it keeps all calculated cells, but can cause large memory consumption (unless there's an inner limit to the queue). Am I wrong to use it this way? Or is it just up to the developper, depending on his needs?

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  • Optimizing website - minification, sprites, etc...

    - by nivlam
    I'm looking at the product Aptimize Website Accelerator, which is an ISAPI filter that will concatenate files, minify css/javascript, and more. Does anyone have experience with this product, or any other "all-in-one" solutions? I'm interesting in knowing whether something like this would be good long-term, or would manually setting up all the components (integrate YUICompress into the build process, setting up gzip compression, tweaking expiration headers, etc...) be more beneficial? An all-in-one solution like this looks very tempting, as it could save a lot of time if our website is "less than optimal". But how efficient are these products? Would setting up the components manually generate better results? Or would the gap between the all-in-one solution and manually setting up the component be so small, that it's negligible?

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  • YUI Compressor and .NET Apps

    - by objektivs
    I want to use YUI Compressor (the original) and use it as part of typical MS build processes (Visual Studio 2008, MSBuild). Does anyone have any guidance or thoughts on this? For example, good ways for incorporating into project, what to do with existing CSS and JS references, and the like. I am happy to hear on the benefits of YUI Compressor .NET and alternatives but I'm mor einterested in use of the original. Thanks Scott

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  • Easiest way of unit testing C code with Python

    - by Jon Mills
    I've got a pile of C code that I'd like to unit test using Python's unittest library (in Windows), but I'm trying to work out the best way of interfacing the C code so that Python can execute it (and get the results back). Does anybody have any experience in the easiest way to do it? Some ideas include: Wrapping the code as a Python C extension using the Python API Wrap the C code using SWIG Add a DLL wrapper to the C code and load it into Python using ctypes Add a small XML-RPC server to the c-code and call it using xmlrpclib (yes, I know this seems a bit far-out!) Is there a canonical way of doing this? I'm going to be doing this quite a lot, with different C modules, so I'd like to find a way which is least effort.

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  • What are good memory management techniques in Flash/as3

    - by Parris
    Hello! So I am pretty familiar with memory management in Java, C and C++; however, in flash what constructs are there for memory management? I assume flash has a sort of virtual machine like java, and I have been assuming that things get garbage collected when they are set to null. I am not sure if this is actually the case though. Also is there a way to force garbage collection in Flash? Any other tips? Thanks

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  • The speed of Ruby and Java.

    - by Simon
    In every benchmark that I found on the web it seems that Ruby is slow, much slower than Java. The Ruby folks just state that it doesn't matter. Could you give me any example that the speed of Ruby on Rails (and the Ruby itself) really doesn't matter?

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  • How to outperform this regex replacement?

    - by spender
    After considerable measurement, I have identified a hotspot in one of our windows services that I'd like to optimize. We are processing strings that may have multiple consecutive spaces in it, and we'd like to reduce to only single spaces. We use a static compiled regex for this task: private static readonly Regex regex_select_all_multiple_whitespace_chars = new Regex(@"\s+",RegexOptions.Compiled); and then use it as follows: var cleanString= regex_select_all_multiple_whitespace_chars.Replace(dirtyString.Trim(), " "); This line is being invoked several million times, and is proving to be fairly intensive. I've tried to write something better, but I'm stumped. Given the fairly modest processing requirements of the regex, surely there's something faster. Could unsafe processing with pointers speed things further?

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  • Retrieve 2 last posts for each category.

    - by Savageman
    Hello, Lets say I have 2 tables: blog_posts and categories. Each blog post belongs to only ONE category, so there is basically a foreign key between the 2 tables here. I would like to retrieve the 2 lasts posts from each category, is it possible to achieve this in a single request? GROUP BY would group everything and leave me with only one row in each category. But I want 2 of them. It would be easy to perform 1 + N query (N = number of category). First retrieve the categories. And then retrieve 2 posts from each category. I believe it would also be quite easy to perform M queries (M = number of posts I want from each category). First query selects the first post for each category (with a group by). Second query retrieves the second post for each category. etc. I'm just wondering if someone has a better solution for this. I don't really mind doing 1+N queries for that, but for curiosity and general SQL knowledge, it would be appreciated! Thanks in advance to whom can help me with this.

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  • Is there an offline version of Smush.it available?

    - by Jonathon Watney
    Sometimes I use Smush.it via the YSlow Firefox plugin to non-destructively reduce the file size of JPG images. Is there an offline version available that runs on Windows? And if not is there an alternative? The reason I'd like an offline version is that I'd like to optimize images before I deploy them. Currently Smush.it accepts only public facing URLs for images or a web page (via YSlow) and can't access my internal network. That means I have to deploy, optimize, replace images and deploy again. I'd really like to deploy the optimized images on the first deploy. Update: Here's a very similar question.

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  • Benchmarking a particular method in Objective-C

    - by Jasconius
    I have a critical method in an Objective-C application that I need to optimize as much as possible. I first need to take some easy benchmarks on this one single method so I can compare my progress as I optimize. What is the easiest way to track the execution time of a given method in, say, milliseconds, and print that to console.

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  • Software to Tune/Calibrate Properties for Heuristic Algorithms

    - by Karussell
    Today I read that there is a software called WinCalibra (scroll a bit down) which can take a text file with properties as input. This program can then optimize the input properties based on the output values of your algorithm. See this paper or the user documentation for more information (see link above; sadly doc is a zipped exe). Do you know other software which can do the same which runs under Linux? (preferable Open Source) EDIT: Since I need this for a java application I will now invest my research in java libraries like jgap. Other ideas and links would be appreciated!

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  • Software to Tune/Calibrate Properties for Heuristic Algorithms

    - by Karussell
    Today I read that there is a software called WinCalibra (scroll a bit down) which can take a text file with properties as input. This program can then optimize the input properties based on the output values of your algorithm. See this paper or the user documentation for more information (see link above; sadly doc is a zipped exe). Do you know other software which can do the same which runs under Linux? (preferable Open Source)

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  • Optimizing Oracle query

    - by Omnipresent
    SELECT MAX(verification_id) FROM VERIFICATION_TABLE WHERE head = 687422 AND mbr = 23102 AND RTRIM(LTRIM(lname)) = '.iq bzw' AND TO_CHAR(dob,'MM/DD/YYYY')= '08/10/2004' AND system_code = 'M'; This query is taking 153 seconds to run. there are millions of rows in VERIFICATION_TABLE. I think query is taking long because of the functions in where clause. However, I need to do ltrim rtrim on the columns and also date has to be matched in MM/DD/YYYY format. How can I optimize this query?

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  • TSQL -- Make it better

    - by user319353
    Hi: -- Very Narrow (all IDs are passed in) IF(@EmpID IS NOT NULL AND @DeptID IS NOT NULL AND @CityID IS NOT NULL) BEGIN SELECT e.EmpName ,d.DeptName ,c.CityName FROM Employee e WITH (NOLOCK) JOIN Department d WITH (NOLOCK) ON e.deptid = d.deptid JOIN City c WITH (NOLOCK) ON e.CityID = c.CityID WHERE e.EmpID = @EmpID END -- Just 2 IDs passed in ELSE IF(@DeptID IS NOT NULL AND @CityID IS NOT NULL) BEGIN SELECT e.EmpName ,d.DeptName ,NULL AS [CityName] FROM Employee e WITH (NOLOCK) JOIN Department d WITH (NOLOCK) ON e.deptid = d.deptid JOIN City c WITH (NOLOCK) ON e.CityID = c.CityID WHERE d.deptID = @DeptID END -- Very Broad (just 1 ID passed in) ELSE IF(@CityID IS NOT NULL) BEGIN SELECT e.EmpName ,NULL AS [DeptName] ,NULL AS [CityName] FROM Employee e WITH (NOLOCK) JOIN Department d WITH (NOLOCK) ON e.deptid = d.deptid JOIN City c WITH (NOLOCK) ON e.CityID = c.CityID WHERE c.CityID = @CityID END -- None (Nothing passed in) ELSE BEGIN SELECT NULL AS [EmpName] ,NULL AS [DeptName] ,NULL AS [CityName] END Question: Is there any better way (OR specifically can I do anything without IF...ELSE condition?

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  • image archive VS image strip

    - by DevA
    Hi, i've noticed that plenty of games / applications (very common on mobile builds) pack numerous images into an image strip. I figured that the advantages in this are making the program more tidy (file system - wise) and reducing (un)installation time. During the runtime of the application, the entire image strip is allocated and copied from FS to RAM. On the contrary, images can be stored in an image archive and unpacked during runtime to a number of image structures in RAM. The way I see it, the image strip approach is less efficient because of worse caching performance and because that even if the optimal rectangle packing algorithm is used, there will be empty spaces between the stored images in the strip, causing a waste of RAM. What are the advantages in using an image strip over using an image archive file?

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  • What's the difference between !col and col=false in MySQL?

    - by Mask
    The two statements have totally different performance: mysql> explain select * from jobs where createIndexed=false; +----+-------------+-------+------+----------------------+----------------------+---------+-------+------+-------+ | id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra | +----+-------------+-------+------+----------------------+----------------------+---------+-------+------+-------+ | 1 | SIMPLE | jobs | ref | i_jobs_createIndexed | i_jobs_createIndexed | 1 | const | 1 | | +----+-------------+-------+------+----------------------+----------------------+---------+-------+------+-------+ 1 row in set (0.01 sec) mysql> explain select * from jobs where !createIndexed; +----+-------------+-------+------+---------------+------+---------+------+-------+-------------+ | id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra | +----+-------------+-------+------+---------------+------+---------+------+-------+-------------+ | 1 | SIMPLE | jobs | ALL | NULL | NULL | NULL | NULL | 17996 | Using where | +----+-------------+-------+------+---------------+------+---------+------+-------+-------------+ Column definition and related index for aiding analysis: createIndexed tinyint(1) NOT NULL DEFAULT 0, create index i_jobs_createIndexed on jobs(createIndexed);

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  • Does visibility affect DOM manipulation performance?

    - by Chetan Sastry
    IE7/Windows XP I have a third party component in my page that does a lot of DOM manipulation to adjust itself each time the browser window is resized. Unfortunately I have little control of what it does internally and I have optimized everything else (such as callbacks and event handlers) as much as I can. I can't take the component off the flow by setting display:none because it fails measuring itself if I do so. In general, does setting visibility of the container to invisible during the resize help improve DOM rendering performance?

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  • Why is shrink_to_fit non-binding?

    - by Roger Pate
    The C++0x FCD states in 23.3.6.2 vector capacity: void shrink_to_fit(); Remarks: shrink_to_fit is a non-binding request to reduce capacity() to size(). [Note: The request is non-binding to allow latitude for implementation-specific optimizations. —end note] Why is it non-binding, and what optimizations are intended to be allowed?

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  • performance issue in a select query from a single table

    - by daedlus
    Hi , I have a table as below dbo.UserLogs ------------------------------------- Id | UserId |Date | Name| P1 | Dirty ------------------------------------- There can be several records per userId[even in millions] I have clustered index on Date column and query this table very frequently in time ranges. The column 'Dirty' is non-nullable and can take either 0 or 1 only so I have no indexes on 'Dirty' I have several millions of records in this table and in one particular case in my application i need to query this table to get all UserId that have at least one record that is marked dirty. I tried this query - select distinct(UserId) from UserLogs where Dirty=1 I have 10 million records in total and this takes like 10min to run and i want this to run much faster than this. [i am able to query this table on date column in less than a minute.] Any comments/suggestion are welcome. my env 64bit,sybase15.0.3,Linux

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  • How can I encode four unsigned bytes (0-255) to a float and back again using HLSL?

    - by Statement
    Hello! I am facing a task where one of my hlsl shaders require multiple texture lookups per pixel. My 2d textures are fixed to 256*256, so two bytes should be sufficient to address any given texel given this constraint. My idea is then to put two xy-coordinates in each float, giving me eight xy-coordinates in pixel space when packed in a Vector4 format image. These eight coordinates are then used to sample another texture(s). The reason for doing this is to save graphics memory and an attempt to optimize processing time, since then I don't require multiple texture lookups. By the way: Does anyone know if encoding/decoding 16 bytes from/to 4 floats using 1 sampling is slower than 4 samplings with unencoded data?

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  • very quickly getting total size of folder

    - by freakazo
    I want to quickly find the total size of any folder using python. def GetFolderSize(path): TotalSize = 0 for item in os.walk(path): for file in item[2]: try: TotalSize = TotalSize + getsize(join(item[0], file)) except: print("error with file: " + join(item[0], file)) return TotalSize That's the simple script I wrote to get the total size of the folder, it took around 60 seconds (+-5 seconds). By using multiprocessing I got it down to 23 seconds on a quad core machine. Using the Windows file explorer it takes only ~3 seconds (Right click- properties to see for yourself). So is there a faster way of finding the total size of a folder close to the speed that windows can do it? Windows 7, python 2.6 (Did searches but most of the time people used a very similar method to my own) Thanks in advance.

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