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  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

  An Object is not a Hash

Following my article A String is not an Error, I want to bring attention to an issue that similarly applies to JavaScript in general, but has special relevance in the Node.JS environment. The problem boils down to the usage of {} as a data-structure where the keys are supplied by untrusted user input, and the mechanisms that are normally used to assert whether a key exists. Consider the example of a simple blog created with Express. We decide to store blog posts in memory in a {}, indexed ...

   Object,Hash,Node.js,JavaScript     2012-01-19 10:16:10

  About browser event

First look at following codes: var $ = KISSY.all; $(‘a’).on(‘click’,function(e){ doSomeThing();//This function seems very famous e.halt(); }); The above codes seem complete the work we want them. The browser will not redirect us to the link in href, but is there some issue with the codes above? Before explaining what's wrong with the above codes, we first need to understand some concepts. Browser default behavior When we click a link, the browser will redirect us to anoth...

   JavaScript event,Event bubbling,event capturing     2012-11-15 11:15:41

  Significance and use of do{...}while(0)

In some Linux kernel and other open source codes, we can see some codes like below: do{ ... }while(0) This code snippet is not a loop, it seems there is no significance of using do...while this way, then why should we use it? In fact, the significance of do{...}while(0) is better than optimizing your code. After some research, we summarize some benefits of it. 1. Help define complex macro to avoid error #define DOSOMETHING()\ foo1();\ foo2(); The me...

   do{...}while(0), optimization     2012-10-21 21:13:22

  About C++ comma operator precedence

When learning programming language, we will always have one topic about the operator precedence. Since there are many operators can be used in one expression, there should be some rules regarding which operation can happen first so that the compiler or interpreter can handle them correctly. One rule of programming with expression is using as much as brackets as you can to avoid unexpected results. Here we refer one problem we see online about the comma operator in C++. The following program has ...

   comma,precedence     2012-11-12 10:25:00

  10 design flaws of JavaScript

JavaScript's design took only ten days. Moreover, the designer didn't want to design it initially, he just wanted to complete the task assigned by company. It is now a very powerful client side programming language used in almost all the websites. It's an excellent language, but it also has some flaws. 1. Not suitable for large projects JavaScript doesn't have namespace, it's hard to be modular, there is no standard for putting codes in multiple source files. It allows defining functions with th...

   JavaScript, Design flaw, Object     2012-11-29 11:39:35

  How to Asynchronously Upload Files Using HTML5 and Ajax

In my previous posts, we discovered How to Use HTML5 File Drag & Drop, and Open Files Using HTML5 and JavaScript. Now we have a valid set of files, it possible to upload each one to the server. The process occurs asynchronously in the background so the user can complete other on-page tasks while it occurs.The HTMLLet’s examine our HTML form again:view plainprint?<form id="upload" action="upload.php" method="POST" enctype="multipart/form-data"> ...

   HTML5,File upload,AJAX,Asynchronously,X-FILENAME     2011-10-29 13:45:00

  Beauty of front end--List of front end tools used by GitHub

I did this summarization when I added Lirate_CoffeeScript support for GitHub-Linguist, i.e how does GitHub do Marjdown render and code highlight in its front end. Lots of font end tools used by GitHub are open sourced. They are: 1. HTML/CSS/JavaScript 1.1 HTML template GitHub markup and template styleguide : https://github.com/styleguide/templates 1.2 Style and CSS GitHub uses replacement of CSS: SCSS：https://github.com/nex3/sass KSS：https://github.com/kneath/kss GitHub CSS styleguide ...

   GitHub, front end,Tool     2013-03-07 03:46:42

  What have been Facebook’s greatest technical accomplishments?

To maintain a large website which gets billions of requests er day and keeps very fast response speed is not an easy task. Many big companies are trying best to improve user experience by adopting different techniques. There is a question on Quora which asks "What have been Facebook’s greatest technical accomplishments?". There is a person who worked in Facebook before provided an answer which helps us understanding how Facebook handles huge amount of traffic each day. Here is the answer f...

   Facebook, Design, Efficiency     2013-01-15 07:32:07

  20 bit operations programmers should know

While talking about bit operation, programmers usually think about its efficiency. In embedded programming and system core optimization, appropriate use of bit operations is always a fascinating. When finding a job, it will help you a lot if you use bit operations when writing codes. Mastering simple bit arithmetic skills is necessary. 1. Get maximum int value int getMaxInt(){           return (1 << 31) - 1;//...

   Bit operation, Tips     2012-12-19 12:53:33

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