Oracle Joins Example

We want to do not only write SQL, but also to do a good performance of the SQL, the following for the author to learn, extract, and summarized part of the information to share with you! (1) Select the most efficient table name order (valid only in the Rule-based optimizer): The ORACLE parser processes the table names in the FROM clause in Right-to-left order, and the last table in the FROM clause (the underlying table driving tables) is processed first, In the case where multiple tables are included in the FROM clause, you must select the table with the least number of records as the underlying table. If...

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 greatest fascination with large data is the new business value that comes from technical analysis and excavation. SQL on Hadoop is a critical direction. CSDN Cloud specifically invited Liang to write this article, to the 7 of the latest technology to do in-depth elaboration. The article is longer, but I believe there must be a harvest. December 5, 2013-6th, "application-driven architecture and technology" as the theme of the seventh session of China Large Data technology conference (DA data Marvell Conference 2013,BDTC 2013) before the meeting, ...

There are two common Cluster (clusters) architectures, one is Web/internet Cluster system, which is to place data on different hosts, that is, multiple hosts are simultaneously responsible for one service, and the other is the so-called parallel operation! Parallel operation is actually the work of the same operation, to the entire Cluster inside the CPU to perform a synchronous operation of a function. Due to the use of multiple CPUs ...

What is Cluster? There are two common Cluster (clusters) architectures, one is Web/internet Cluster system, which is to place data on different hosts, that is, multiple hosts are simultaneously responsible for one service, and the other is the so-called parallel operation! Parallel operation is actually the work of the same operation, to the entire Cluster inside the CPU to perform a synchronous operation of a function ...

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 ...

In 2012, there will be some big competition in cloud computing, mobile and large data, according to IDC researchers. "Many companies such as Microsoft, Hewlett-Packard, SAP, RIM, Apple, etc., will encounter a ' Crossroads crisis ' in 2012." In our view, some of these industry leaders will disappear at the end of the decade, "said Frank Gens, senior vice president and chief analyst at IDC. Other trends in IDC's forecasts for 2012 will include: Corporate spending on mobile computing, cloud services, social networking, and large data analysis technologies ...