《Cracking the Coding Interview》——第10章：可扩展性和存储空间限制——题目1

2014-04-24 00:38

题目：加入你要设计一个服务，供至多1000个client查询每日股票的最高、最低、开盘、收盘价，请描述你要如何设计这个服务。

解法：可以用SQL数据库组织，也可以用K-V数据库来提供更高性能。如果股票数量相对不大，还可以用XML文件组织数据。在百度里搜“BIDU”，或在Google里搜“GOOG”，就能看见例子了。

代码：

// 10.1 Suppose you're to design the backend part of a system, which provides queries of real-time stock prices. How would you do it?
// Answer:
//    Go and search "GOOG" on Google or Baidu, you'll get the real-time stock price of Google. The data transferring is best done with AJAX to the frontend, which can greatly save the amount of data transferred.
//    As for the backend part, you have to use some techniques to store the data:
//        1. SQL database, easy for various kinds of structured queries. You won't expose the direct SQL API to external users because it is not safe. Write a wrapper with the web programming language.
//            Strength: Ability to provide more information than you expected.
//            Weakness: Not so agile, if the data structure changes. Altering a SQL table is always expensive.
//        2. XML files, a good way to store structured data. Good performance when the data scale is small or medium.
//            Strength: Agile, easy to modify the schema. Regenerating the XML file is usually easy with script languages such as python.
//            Weakness: Not suitable for large data scale, as you have to parse everything in the XML only to find an item inside.
//        3. No-SQL database
//            Strength: suitable for large scale, high concurrency, flexible with data schema changes.
//            Weakness: Don't know yet, maybe more space usage.
int main()
{
    return 0;
}