Hello Stack Overflow Community, I have a list where I want to replace values with None where condition() returns True. [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10] For example, if condition checks bool(item%2) should return: [None, 1, None, 3, None, 5, None, 7, None, 9, None] What is the most efficient way to do this? ...
I have a text file that I need to retrieve to populate a web page. My first instinct was to use System.IO.File to open and read the file contents. then it occured to me I could also use a web request (since the file lives on the webserver). I'm wondering which one is a better choice. I figure using the file system would be faster, sinc...
I'm testing out the PostgreSQL Text-Search features, using the September data dump from StackOverflow as sample data. :-) The naive approach of using LIKE predicates or POSIX regular expression matching to search 1.2 million rows takes about 90-105 seconds (on my Macbook) to do a full table-scan searching for a keyword. SELECT * FROM P...
I have 3 DB Tables: Person, Address, and PersonAddress. Person Address is a simple join table (only stores the IDs of Person and Address). In my domain model, I have Person and Address. Person is configured to have a many-to-many relationship to Address (through PersonAddress). In code, this is implemented with List<Address>. I've been...
Say I have two MyISAM tables: tab_big: id1, id2, id_a, ord (5 billion records) tab_small: id1, id2, id_b (1 billion records) CREATE TABLE IF NOT EXISTS `tab_big` ( `id_a` int(10) unsigned NOT NULL, `id1` int(10) unsigned NOT NULL, `id2` int(10) unsigned NOT NULL, `ord` int(10) unsigned NOT NULL DEFAULT '...
I want to save memory by converting an existing 32 bit counter to a 16 bit counter. This counter is atomically incremented/decremented. If I do this: What instructions do I use for atomic_inc(uint16_t x) on x86/x86_64? Is this reliable in multi-processor x86/x86_64 machines? Is there a performance penalty to pay on any of these a...
I want to benchmark a new server using historical HTTP-request data. I have a textfile that contains one day's worth of real historical requests to a production server. What is the best tool for sending that list of requests on the server I'm testing? The tool I use should be able to configure the following: Number of threads making th...
I am working on writing BDD specifications for a broad set of WCF service infrastructure I am writing. I have noticed that each specification I write that involves a call to ServiceHost.Open(), that line takes a good 2 - 6 seconds to execute (the time keeps growing as I add more and more specs). I noticed that when this method is called,...
I have this for-each-loop: for (Component c : container.getComponents()) { // Loop code } Is getComponents called on every iteration? Does it make sense to call getComponents before the look and only work on a cached array? ...
During the performance testing of our ASP.NET MVC application I discovered interesting bottle neck. The application is using only 3 managed threads. I checked maximum thread pool size. It's 200 and we are having 197 available threads. I checked connection limit of web site and it's unlimited. I tried to run stress test locally agains...
I'm using MySQL LIMIT to display 50 rows (pages) at a time, like so: SELECT cols FROM table LIMIT 49, 50 What's the most efficient way for me to determine how many "pages" I have in my result set (how many total records my query is producing)? Before I run the code above, should I just run a quick and dirty: SELECT COUNT(cols) FROM ...
I have been working with SQL server for a while and have used lot of performance techniques to fine tune many queries. Most of these queries were to be executed within few seconds or may be minutes. I am working with a job which loads around 100K of data and runs for around 10 hrs. What are the things I need to consider while writing ...
What methods are there for indentifying superfluous columns in covering indices: columns which are never searched against, and therefore may be extracted into Include's, or even removed completely without affecting the applicability of the index? ...
If I run the following queries each one returns quickly (0.01 sec) and gives me my desired result. SELECT tagId FROM tag WHERE name='programming' SELECT COUNT(DISTINCT workcode) FROM worktag WHERE tagId=123 OR tagId=124 (assume the two tagId numbers were the results from the first query) I would like to combine these queries so I onl...
Is there some reason that identical math operations would take significantly longer in one Silverlight app than in another? For example, I have some code that takes a list of points and transforms them (scales and translates them) and populates another list of points. It's important that I keep the original points intact, hence the sec...
Hi, Loose coupling is wonderful of course, but I have often wondered what overhead wiring up dynamically using an IoC container (for example Castle Windsor) has over a tightly coupled system? I know that a detailed answer would depend on what the IoC was being used for, but I'm really just trying to get a feel for the magnitude of effo...
Two (somewhat separate) questions I have are: Is it a good approach to put performance optimization as a separate skill-set backed up by line items (instead of just 2 words in "skills")? Do the items i put as examples below sound like useful/braggable data to distinguish oneself to a hiring technical manager (whether I put them on a r...
For a project I'm working on I'm trying to create a Flash file with a constantly color-shifting gradient that fills up the entire browser window. For a better explanation please see the following link: GradientTest Example Don't worry about the moving balls, those are just there to challenge the frameRate of the movie, which has a maxi...
I'm relatively well versed in designing websites. I mostly go for LAMP where I already have a small "framework" of my own, that I use. In short, it separates the logic from the layout and I have basically one logic file to one or many layout files depending on what views are supported in the layout. There's an admin section and there are...
I have a web application written in PHP. It uses MySQL for data storage. Today I decided to profile it to find bottlenecks in code and find which parts of it are running slower that the others. The usual stuff. I did a lot of work and now my page loads in less than 0.05 seconds on my desktop. But now my profiler tells me that half of th...