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  • Does anybody have any suggestions on which of these two approaches is better for large delete?

    - by RPS
    Approach #1: DECLARE @count int SET @count = 2000 DECLARE @rowcount int SET @rowcount = @count WHILE @rowcount = @count BEGIN DELETE TOP (@count) FROM ProductOrderInfo WHERE ProductId = @product_id AND bCopied = 1 AND FileNameCRC = @localNameCrc SELECT @rowcount = @@ROWCOUNT WAITFOR DELAY '000:00:00.400' Approach #2: DECLARE @count int SET @count = 2000 DECLARE @rowcount int SET @rowcount = @count WHILE @rowcount = @count BEGIN DELETE FROM ProductOrderInfo WHERE ProductId = @product_id AND FileNameCRC IN ( SELECT TOP(@count) FileNameCRC FROM ProductOrderInfo WITH (NOLOCK) WHERE bCopied = 1 AND FileNameCRC = @localNameCrc ) SELECT @rowcount = @@ROWCOUNT WAITFOR DELAY '000:00:00.400' END

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  • Optimizing this "Boundarize" method for Numerics in Ruby

    - by mstksg
    I'm extending Numerics with a method I call "Boundarize" for lack of better name; I'm sure there are actually real names for this. But its basic purpose is to reset a given point to be within a boundary. That is, "wrapping" a point around the boundary; if the area is betweeon 0 and 100, if the point goes to -1, -1.boundarize(0,100) = 99 (going one too far to the negative "wraps" the point around to one from the max). 102.boundarize(0,100) = 2 It's a very simple function to implement; when the number is below the minimum, simply add (max-min) until it's in the boundary. If the number is above the maximum, simply subtract (max-min) until it's in the boundary. One thing I also need to account for is that, there are cases where I don't want to include the minimum in the range, and cases where I don't want to include the maximum in the range. This is specified as an argument. However, I fear that my current implementation is horribly, terribly, grossly inefficient. And because every time something moves on the screen, it has to re-run this, this is one of the bottlenecks of my application. Anyone have any ideas? module Boundarizer def boundarize min=0,max=1,allow_min=true,allow_max=false raise "Improper boundaries #{min}/#{max}" if min >= max new_num = self if allow_min while new_num < min new_num += (max-min) end else while new_num <= min new_num += (max-min) end end if allow_max while new_num > max new_num -= (max-min) end else while new_num >= max new_num -= (max-min) end end return new_num end end class Numeric include Boundarizer end

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  • glDrawArrays() slow on iPad?

    - by Nick
    Hey guys, I was wondering how to speed up my iPad application using OpenGLES 2.0. At the moment we have every drawable object draw itself with a call to glDrawArrays(). Blend mode is on, we really need it. Without disabling blendmode, how would we improve performance for this app? For instances, if we now draw 1 texture across the whole screen, the app only gets 15FPS, which is really slow I think? Are we doing something terribly wrong? Our drawing code (for each drawable), is as follows: - (void) draw { GLuint textureAvailable = 0; if(texture != nil){ textureAvailable = 1; } glActiveTexture(GL_TEXTURE0); glBindTexture(GL_TEXTURE_2D, texture.name); glVertexAttribPointer(ATTRIB_VERTEX, 2, GL_FLOAT, 0, 0, vertices); glEnableVertexAttribArray(ATTRIB_VERTEX); glVertexAttribPointer(ATTRIB_COLOR, 4, GL_FLOAT, 1, 0, colorsWithMultipliedAlpha); glEnableVertexAttribArray(ATTRIB_COLOR); glVertexAttribPointer(ATTRIB_TEXTUREMAP, 2, GL_FLOAT, 1, 0, textureMapping); glEnableVertexAttribArray(ATTRIB_TEXTUREMAP); //Note that we are NOT using position.z here because that is only used to determine drawing order int *jnUniforms = JNOpenGLConstants::getInstance().uniforms; glUniform4f(jnUniforms[UNIFORM_TRANSLATE], position.x, position.y, 0.0, 0.0); glUniform4f(jnUniforms[UNIFORM_SCALE], scale.x, scale.y, 1.0, 1.0); glUniform1f(jnUniforms[UNIFORM_ROTATION], rotation); glUniform1i(jnUniforms[UNIFORM_TEXTURE_SAMPLE], 0); glUniform2f(jnUniforms[UNIFORM_TEXTURE_REPEAT], textureRepeat.x, textureRepeat.y); glUniform1i(jnUniforms[UNIFORM_TEXTURE_AVAILABLE], textureAvailable); glDrawArrays(GL_TRIANGLE_STRIP, 0, 4); }

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  • Is a program compiled with -g gcc flag slower than the same program compiled without -g?

    - by e271p314
    I'm compiling a program with -O3 for performance and -g for debug symbols (in case of crash I can use the core dump). One thing bothers me a lot, does the -g option results in a performance penalty? When I look on the output of the compilation with and without -g, I see that the output without -g is 80% smaller than the output of the compilation with -g. If the extra space goes for the debug symbols, I don't care about it (I guess) since this part is not used during runtime. But if for each instruction in the compilation output without -g I need to do 4 more instructions in the compilation output with -g than I certainly prefer to stop using -g option even at the cost of not being able to process core dumps. How to know the size of the debug symbols section inside the program and in general does compilation with -g creates a program which runs slower than the same code compiled without -g?

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  • How to optimize a postgreSQL server for a "write once, read many"-type infrastructure ?

    - by mhu
    Greetings, I am working on a piece of software that logs entries (and related tagging) in a PostgreSQL database for storage and retrieval. We never update any data once it has been inserted; we might remove it when the entry gets too old, but this is done at most once a day. Stored entries can be retrieved by users. The insertion of new entries can happen rather fast and regularly, thus the database will commonly hold several millions elements. The tables used are pretty simple : one table for ids, raw content and insertion date; and one table storing tags and their values associated to an id. User search mostly concern tags values, so SELECTs usually consist of JOIN queries on ids on the two tables. To sum it up : 2 tables Lots of INSERT no UPDATE some DELETE, once a day at most some user-generated SELECT with JOIN huge data set What would an optimal server configuration (software and hardware, I assume for example that RAID10 could help) be for my PostgreSQL server, given these requirements ? By optimal, I mean one that allows SELECT queries taking a reasonably little amount of time. I can provide more information about the current setup (like tables, indexes ...) if needed.

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  • In SQL Server what is most efficient way to compare records to other records for duplicates with in

    - by Glenn
    We have an SQL Server that gets daily imports of data files from clients. This data is interrelated and we are always scrubbing it and having to look for suspect duplicate records between these files. Finding and tagging suspect records can get pretty complicated. We use logic that requires some field values to be the same, allows some field values to differ, and allows a range to be specified for how different certain field values can be. The only way we've found to do it is by using a cursor based process, and it places a heavy burden on the database. So I wanted to ask if there's a more efficient way to do this. I've heard it said that there's almost always a more efficient way to replace cursors with clever JOINS. But I have to admit I'm having a lot of trouble with this one. For a concrete example suppose we have 1 table, an "orders" table, with the following 6 fields. order_id, customer_id product_id, quantity, sale_date, price We want to look through the records to find suspect duplicates on the following example criteria. These get increasingly harder. 1. Records that have the same product_id, sale_date, and quantity but different customer_id's should be marked as suspect duplicates for review. 2. Records that have the same customer_id, product_id, quantity and have sale_dates within five days of each other should be marked as suspect duplicates for review 3. Records that have the same customer_id, product_id, but different quantities within 20 units, and sales dates within five days of each other should be considered suspect. Is it possible to satisfy each one of these criteria with a single SQL Query that uses JOINS? Is this the most efficient way to do this?

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  • STL vectors with uninitialized storage?

    - by Jim Hunziker
    I'm writing an inner loop that needs to place structs in contiguous storage. I don't know how many of these structs there will be ahead of time. My problem is that STL's vector initializes its values to 0, so no matter what I do, I incur the cost of the initialization plus the cost of setting the struct's members to their values. Is there any way to prevent the initialization, or is there an STL-like container out there with resizeable contiguous storage and uninitialized elements? (I'm certain that this part of the code needs to be optimized, and I'm certain that the initialization is a significant cost.) Also, see my comments below for a clarification about when the initialization occurs. SOME CODE: void GetsCalledALot(int* data1, int* data2, int count) { int mvSize = memberVector.size() memberVector.resize(mvSize + count); // causes 0-initialization for (int i = 0; i < count; ++i) { memberVector[mvSize + i].d1 = data1[i]; memberVector[mvSize + i].d2 = data2[i]; } }

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  • Will unused deconstructors be optimized out?

    - by Brendan Long
    Assuming MyClass uses the default deconstructor (or no deconstructor), and this code: MyClass buffer[] = new MyClass[i]; // Construct N objects using placement new for(size_t i = 0; i < N; i++){ ~buffer[i]; } delete[] buffer; Is there any optimizer that would be able to remove this loop? Also, is there any way for my code to detect if MyClass is using an empty/default constructor?

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  • PHP Increasing writing to page speed.

    - by Frederico
    I'm currently writing out xml and have done the following: header ("content-type: text/xml"); header ("content-length: ".strlen($xml)); $xml being the xml to be written out. I'm near about 1.8 megs of text (which I found via firebug), it seems as the writing is taking more time than the script to run.. is there a way to increase this write speed? Thank you in advance.

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  • optimized grid for rectangular items

    - by peterchen
    I have N rectangular items with an aspect ratio Aitem (X:Y). I have a rectangular display area with an aspect ratio Aview The items should be arranged in a table-like layout (i.e. r rows, c columns). what is the ideal grid rows x columns, so that individual items are largest? (rows * colums = N, of course - i.e. there may be "unused" grid places). A simple algorithm could iterate over rows = 1..N, calculate the required number of columns, and keep the row/column pair with the largest items. I wonder if there's a non-iterative algorithm, though (e.g. for Aitem = Aview = 1, rows / cols can be approximated by sqrt(N)).

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  • Ways to optimize Android App code based on function call stack?

    - by K-RAN
    I've been told that Android OS stores all function calls in a stack. This can lead to many problems and cause the 'hiccups' during runtime, even if a program is functionalized properly, correct? So the question is, how can we prevent this from happening? The obvious solution is to functionalize less, along with other sensible acts such as refraining from excessively/needlessly creating objects, performing static calls to functions that don't access fields, etc... Is there another way though? Or can this only be done through careful code writing on the programmers' part? Does the JVM/JIT automatically optimize the bytecode during compile time to account for this?? Thanks a lot for your responses!!

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  • optimize python code

    - by user283405
    i have code that uses BeautifulSoup library for parsing. But it is very slow. The code is written in such a way that threads cannot be used. Can anyone help me about this? I am using beautifulsoup library for parsing and than save in DB. if i comment the save statement, than still it takes time so there is no problem with database. def parse(self,text): soup = BeautifulSoup(text) arr = soup.findAll('tbody') for i in range(0,len(arr)-1): data=Data() soup2 = BeautifulSoup(str(arr[i])) arr2 = soup2.findAll('td') c=0 for j in arr2: if str(j).find("<a href=") > 0: data.sourceURL = self.getAttributeValue(str(j),'<a href="') else: if c == 2: data.Hits=j.renderContents() #and few others... #... c = c+1 data.save() Any suggestions? Note: I already ask this question here but that was closed due to incomplete information.

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  • How to simplify my code... 2D array in Objective C...?

    - by Tattat
    self.myArray = [NSArray arrayWithObjects: [NSArray arrayWithObjects: [self d], [self generateMySecretObject],nil], [NSArray arrayWithObjects: [self generateMySecretObject], [self generateMySecretObject],nil],nil]; for (int k=0; k<[self.myArray count]; k++) { for(int s = 0; s<[[self.myArray objectAtIndex:k] count]; s++){ [[[self.myArray objectAtIndex:k] objectAtIndex:s] setAttribute:[self generateSecertAttribute]]; } } As you can see this is a simple 2*2 array, but it takes me lots of code to assign the NSArray in very first place, because I found that the NSArray can't assign the size at very beginning. Also, I want to set attribute one by one. I can't think of if my array change to 10*10. How long it could be. So, I hope you guys can give me some suggestions on shorten the code, and more readable. thz

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  • PHP what is faster to use

    - by user1631500
    What is faster / better to use? To put html into variables and print them later, or to just html print / echo print the content based on condition? EXAMPLE 1:(html into variables) if(!isset($_SESSION['daddy'])) { $var = "<span class='something'>Go here:<a href='#'>Click</a></span> <span class='something'>Go here:<a href='#'>Click</a></span>" } else { $one=$_SESSION["one"]; $two=$_SESSION["two"]; $three=$_SESSION["three"]; $var = You are cool enough to view the content; } echo $var; EXAMPLE 2:(print based on condition) if(!isset($_SESSION['daddy'])) { $var = 1; } else { $one=$_SESSION["one"]; $two=$_SESSION["two"]; $three=$_SESSION["three"]; $var = 0; } if ($var==1) { ?> <span class='something'>Go here:<a href='#'>Click</a></span> <span class='something'>Go here:<a href='#'>Click</a></span <?php } else { ?> You are cool enough to view the content. <?php } ?>

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  • PHP error handling : my code is not optimized

    - by Tristan
    Hello, I must warn you, this code will heart your eyes, so please don't judge me, i'm trying to improve the way I handle errors all my tests are like this : if ($something < 27) { $error_IP= '<div class="error_message">something bad</div> '; }else{ $erreur_IP=''; } and here's the ugliest thing : if( !isset($_POST) || ($erreur_captcha !='') || ($erreur_email !='') || ($erreur_hebergeurVide != '') || ($erreur_paysVide != '') || ($erreur_slotVide != '') || ($erreur_rconVide != '') || ($erreur_tick != '') + a lot more :d ) What do you suggest to me to optimize my errors handling ? Thank you

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  • Optimize Binary Search Algorithm

    - by Ganesh M
    In a binary search, we have two comparisons one for greater than and other for less than, otherwise its the mid value. How would you optimize so that we need to check only once? bool binSearch(int array[], int key, int left, int right) { mid = left + (right-left)/2; if (key < array[mid]) return binSearch(array, key, left, mid-1); else if (key > array[mid]) return binSearch(array, key, mid+1, right); else if (key == array[mid]) return TRUE; // Found return FALSE; // Not Found }

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