Add Primary Key To Existing Table Oracle

The logical design of database is a very broad problem. In this paper, the main key design of the table is discussed in the design of MS SQL Server, and the corresponding solutions are given. Primary key design status and problems about database table primary key design, in general, based on business requirements, based on business logic, the formation of primary key. For example, when sales to record sales, generally need two tables, one is the summary description of the sales list, records such as sales number, the total amount of a class of cases, and the other table record of each commodity ...

After more than eight years of practice, from Taobao's collection business to today to support all of Alipay's core business, and in the annual "Double Eleven Singles Day" continue to create a world record for the transaction database peak processing capacity.

The storage system is the core infrastructure of the IT environment in the data center, and it is the final carrier of data access. Storage in cloud computing, virtualization, large data and other related technologies have undergone a huge change, block storage, file storage, object storage support for a variety of data types of reading; Centralized storage is no longer the mainstream storage architecture of data center, storage access of massive data, need extensibility, 　　Highly scalable distributed storage architecture. In the new IT development process, data center construction has entered the era of cloud computing, enterprise IT storage environment can not be simple ...

This paper is an excerpt from the book "The Authoritative Guide to Hadoop", published by Tsinghua University Press, which is the author of Tom White, the School of Data Science and engineering, East China Normal University. This book begins with the origins of Hadoop, and integrates theory and practice to introduce Hadoop as an ideal tool for high-performance processing of massive datasets. The book consists of 16 chapters, 3 appendices, covering topics including: Haddoop;mapreduce;hadoop Distributed file system; Hadoop I/O, MapReduce application Open ...

Intermediary transaction SEO diagnosis Taobao Guest Cloud mainframe technology hall with the advent of the 11 long holiday, everyone to the Ministry of Railways 12306 of the discussion again. This article (original) from 12306 website extension to the site performance of a lot of discussion, for entrepreneurs and technology enthusiasts have a strong reference. 　　The author Chenhao (Weibo) has 14 years of experience in software development, 8 years of project and team management experience. 12306.cn website Hung, was scolded by the people all over the country. I've been here for two days.

First, the initial understanding of large data seems to be overnight, big data becomes one of the most fashionable words in the IT industry. First of all, big data is not a completely new thing, Google's search service is a typical large data use, according to customer demand, Google real-time from the global mass of digital assets (or digital garbage) ...