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  7 misunderstandings of DNS resolution

DNS resolution is generally considered as providing mapping between domain name and IP address, for example www.google.com maps to 74.125.71.103. There are two important reasons for doing DNS resolution: IP address is hard to remember, while domain name is human friendly Virtual host may access different contents according to the header of the host domain name(sub-domain name) Some webmasters may have some unreasonable requirements when doing DNS resolution. It mainly because they are not very...

   DNS resolution,misunderstanding     2012-10-20 12:57:16

  A guide on installing and running Clickhouse on macOS

ClickHouse is a high-performance open-source columnar database management system developed by Yandex. Here are some of the key features of ClickHouse: Columnar storage: ClickHouse uses a columnar storage format, which allows it to efficiently store and retrieve data by column, rather than by row. This results in much faster query performance, especially for analytical and aggregate queries. Real-time data processing: ClickHouse is designed to handle real-time data processing and can handle bill...

   CLICKHOUSE,MACOS     2023-02-15 06:04:55

  MySQL Index Merge Optimization Practices

In production environment databases, it is often seen that some SQL where conditions include: equal condition on a normal index + primary key range query + order by limit Although using a normal index would be more efficient, the system chooses to use index merge instead in some cases. This article explores such index merge situations. Index Merge Official Introduction   The Index Merge access method retrieves rows with multiple range scans and merges their results into one. Generall...

   INDEX MERGE,MYSQL,PRIMARY INDEX,SECONDARY INDEX     2024-09-10 04:52:26

  Essential Rules To Protect Your Credit Card When Shopping Online

You have to protect yourself and your credit card online while shopping. There are a number of ways to do this, but some prove more technical than others. Your basic best defense includes sensible use and layers of protection. The best way to do this is to pick and choose which stores at which you charge purchases. You can reduce the chance of losing your card details to a thief by declining to allow the retailer to store your credit card. Use a password manager to save your passwords and make a...

   SECURITY,CREDIT CARD,MASTERCARD     2019-10-09 08:40:07

  Permutation algorithm with JavaScript

In secondary school, we have learned permutation. Basically, for n numbers, the number of permutations for these n numbers can be calculated to n! which is called 'n factorial'. But to display all the permutations on the screen, we need to use a recursive function. The problem is how to write this function.  Next I write a program to display the permutations for n numbers with JavaScript. First, we need to understand that from these n numbers, we can first take any one number from it, and t...

   JavaScript,Permutation,Algorithm,Impleme     2011-09-21 12:02:35

  Mozilla releases a web identity system : Persona

Now almost every website requires the user to register, there are many benefits of registration for a website, such as retaining users, accommodating discussions, providing customized content and so on.But there is too much trouble if each site requires registration, right?Of course, users can also have their own way, for those less important sites, for example, using a unified user name, password and email so that you only need to remember one account. Then, we also see some advanced methods em...

   Mozilla,Persona,Security,ID     2012-09-28 12:02:25

  Sorry, I don't want to download your fucking app

You should not claim yourself as a mobile Internet service provider if your product doesn't have an App nowadays. The topic cannot get away from App when we talk on bus, restaurant. Recently it becomes a little bit quiet, but the app wind does not seem to stop, it seems every website may have an App. According to data released by Apple a couple of days ago, its application store app downloads already exceeded 50 billion. However some people are not happy with this.Some people created a blog ...

   App,Update,Force download     2013-05-19 02:50:02

  Traditional recursion vs Tail recursion

Recursion is a frequently adopted pattern for solving some sort of algorithm problems which need to divide and conquer a big issue and solve the smaller but the same issue first. For example, calculating fibonacci  accumulating sum and calculating factorials. In these kinds of issues, recursion is more straightforward than their loop counterpart. Furthermore, recursion may need less code and looks more concise. For example, let's calculate sum of a set of numbers starting with 0 and st...

   ALGORITHM,RECURSION,TAIL RECURSION,TRADITIONAL RECURSION     2016-09-23 23:54:09

  Different types of font icons

A website with just text belongs to the pre Web 2.0 era. A modern site will have different icons appearing on different places on the site. This will give the visitor a better visual feeling. But to have a set of consistent and well crafted icons is not an easy task. It may even require a dedicated icon designer to design them. Fortunately, we now can use font icons provided by many people around the web. Today we will introduce some of them. Font Awesome Font Awesome is an open source font ico...

   font icon, web design, font awesome     2015-07-19 06:22:48

  Tencent released Q1 earning report of 2013

Tencent has released the earnings report of Q1 in 2013, the total revenue is $2.1611 billion which increases  11.5% compared to last quarter and increases 40.4% compared to the same time last year. The  profit is 649.4 million US dollars which increases 17.3% compared to last quarter and increases 37.4% compared last year.The three main profit generators are:1. Value-added services revenue of 1.7014 billion US dollars with an increase of 13.6% compared to last quarter and an increase o...

   Tencent,Earnings report,WeChat     2013-05-15 07:02:45

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