SEARCH KEYWORD -- Heap memory
MySQL index optimization
Problem description: We need to access a very big table which has 40 million records. In the table, id is the primary key and program_id is indexed. When executing a select query: select * from program_access_log where program_id between 1 and 4000 The above query executes very slowly, we thought it was because there were too many records in the table. So we added id in the where condition to limit the search so that each time only half a million records would be read. select * fr...
MySQL,Index search, Partition 2012-12-26 13:14:20
Samsung will release 10.1 inch Windows RT Tablet
Today, Samsung not only announced Galaxy Note â…¡, first Windows Phone 8 device Ativ S and camera EK-GC100 Galaxy equipped with Android 4.1 system, but also announced a Windows RT Tablet PC Samsung Ativ Tab.The 10.1-inch Samsung Ativ Tab has a resolution of 1366 x 768,1.5 GHz dual-core processor, 2G RAM, a 32/64G storage space, support for microSD memory expansion. Other configurations as well as the standard Wi-Fi and Bluetooth 4.0, support for USB 2.0, uHDMI and NFC.In addition, the table...
Everything You Thought You Knew About Learning Is Wrong
Taking notes during class? Topic-focused study? A consistent learning environment? All are exactly opposite the best strategies for learning. Really, I recently had the good fortune to interview Robert Bjork, director of the UCLA Learning and Forgetting Lab, distinguished professor of psychology, and massively renowned expert on packing things in your brain in a way that keeps them from leaking out. And it turns out that everything I thought I knew about learning is wrong. Here’s wh...
Eight C++ programming mistakes the compiler won’t catch
C++ is a complex language, full of subtle traps for the unwary. There is an almost infinite number of ways to screw things up. Fortunately, modern compilers are pretty good at detecting a large number of these cases and notifying the programmer via compile errors or warnings. Ultimately, any error that is compiler-detectable becomes a non-issue if properly handled, as it will be caught and fixed before the program leaves development. At worst, a compiler-detectable error results in los...
C++,Compiler,Error detection 2012-04-08 09:55:20
In-memory key-value store in C, Go and Python
Subtitle: Wow Go’s net library is fast On paternity leave for my second child, I found myself writing an in-memory hashmap (a poor-man’s memcached), in Go, Python and C. I was wondering how hard it would be to replace memcached, if we wanted to do something unusual with our key-value store. I also wanted to compare the languages, and, well, I get bored easily! The code is on github as Key-Value-Polyglot. Each version implements enough of the get and set commands from the mem...
Facebook open sources its C++ library named Folly
Recently, Facebook open sourced its low level C++ function library for its internal use named Folly. Folly is an open sourced C++11 component library, it provides functions similar to what boost and std libraries provide, including string, vector and memory allocation, bit operation etc, to fulfill large scale high performance requirements.Currently Folly is tested with gcc4.6 on some 64 bit systems such as Fedora 17, Ubuntu 12.04 and Debian wheezy, it may also be OK on other 64 bit platforms wi...
Facebook,Folly,C++,open source 2012-06-05 08:31:12
In defence of Objective-C
An unashamed apologist’s perspective on the loveliest language i’ve worked with.I’ve worked with a lot of programming languages in my time. Not a huge number, mind you, but enough that i can say that i’m open minded and seasoned about it. And, as they say: ‘Don’t feed the trolls’ – well, i’m about to do exactly that: feed the trolls at work who love to rag on about how awful obj-c is! So here i go, foolishly treading where no sensible...
Apple,Objective-C,Syntax,Defense,Memory management 2011-10-17 11:28:39
Management Myth #1: The Myth of 100% Utilization
A manager took me aside at a recent engagement. “You know, Johanna, there’s something I just don’t understand about this agile thing. It sure doesn’t look like everyone is being used at 100 percent.â€â€œAnd what if they aren’t being used at 100 percent? Is that a problem for you?â€â€œHeck, yes. I’m paying their salaries! I want to know I’m getting their full value for what I’m paying them!â€â€œWhat if I told you...
Management,Utilization,Efficiency,Innovation 2012-01-05 08:13:41
Programming Languages for Machine Learning Implementations
Machine learning algorithms have a much better chance of being widely adopted if they are implemented in some easy-to-use code. There are several important concerns associated with machine learning which stress programming languages on the ease-of-use vs. speed frontier.Speed The rate at which data sources are growing seems to be outstripping the rate at which computational power is growing, so it is important that we be able to eak out every bit of computational power. Garbage collected la...
Programming language,Machine learning,Development 2011-11-16 08:22:17
Pointers, arrays, and string literals
A recently posted question on Stack Overflow highlighted a common misconception about the role of pointers and arrays held by many programmers learning C.The confusion stems from a misunderstanding concerning the role of pointers and strings in C. A pointer is an address in memory. It often points to an index in an array, such as in the function strtoupper in the following code:void strtoupper(char *str) { if (str) { // null ptr check, courtesy of Michael while (...
char pointer,initialization,literal,cann 2011-09-22 13:29:23
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