Java Long Null

In the past few years, the innovative development of the open source world has elevated the productivity of Java™ developers to one level. Free tools, frameworks and solutions make up for once-scarce vacancies. The Apache CouchDB, which some people think is a WEB 2.0 database, is very promising. It's not difficult to master CouchDB, it's as simple as using a Web browser. This issue of Java open ...

To use Hadoop, data consolidation is critical and hbase is widely used. In general, you need to transfer data from existing types of databases or data files to HBase for different scenario patterns. The common approach is to use the Put method in the HBase API, to use the HBase Bulk Load tool, and to use a custom mapreduce job. The book "HBase Administration Cookbook" has a detailed description of these three ways, by Imp ...

Take the XX data file from the FTP host. 　　Tens not just a concept, represents data that is equal to tens of millions or more than tens of millions of data sharing does not involve distributed collection and storage and so on. Is the processing of data on a machine, if the amount of data is very large, you can consider distributed processing, if I have this experience, will be in time to share. 　　1, the application of the FTP tool, 2, tens the core of the FTP key parts-the list directory to the file, as long as this piece is done, basically the performance is not too big problem. You can pass a ...

Due to the requirements of the project, it is necessary to submit yarn MapReduce computing tasks through Java programs. 　　Unlike the general task of submitting MapReduce through jar packages, a small change is required to submit mapreduce tasks through the program, as detailed in the following code. 　　The following is MapReduce main program, there are a few points to mention: 1, in the program, I read the file into the format set to Wholefileinputformat, that is, not to the file segmentation. 2, in order to control the treatment of reduce ...

1. HQueue profile HQueue is a set of distributed, persistent message queues developed by hbase based on the search web crawl offline Systems team. It uses htable to store message data, HBase coprocessor to store the original keyvalue data in the message data format, and encapsulates the HBase client API for message access based on the HQueue client API. HQueue can be effectively used in the need to store time series data, as MAPR ...

In Java Web Development, it is often necessary to export a large amount of data to http://www.aliyun.com/zixun/aggregation/16544.html ">excel, using POI, JXL directly generate Excel, 　　It is easy to cause memory overflow. 　　1, there is a way, is to write data in CSV format file. 　　1 CSV file can be opened directly with Excel. 2 Write CSV file efficiency and write TXT file efficiency ...

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 ...

This article is my second time reading Hadoop 0.20.2 notes, encountered many problems in the reading process, and ultimately through a variety of ways to solve most of the. 　　Hadoop the whole system is well designed, the source code is worth learning distributed students read, will be all notes one by one post, hope to facilitate reading Hadoop source code, less detours. 1 serialization core Technology The objectwritable in 0.20.2 version Hadoop supports the following types of data format serialization: Data type examples say ...

Overview 1, what is C #? C # is a programming language designed by Microsoft. 　　It is loosely based on C + +, and there are many aspects similar to Java. Microsoft describes C # in this way: "C # is a simple, modern, object-oriented, and type-safe programming language derived from C and C + +." C # (read ' Csharp ') has been ported mainly from a family of + + + + programming languages, and the programmers of both C. and C + + are immediately familiar with it. C # attempts to combine Visual Basic's ...

At present, what is cloud computing, what kind of platform belongs to the cloud computing platform, and so on cloud computing related issues, different hardware and software manufacturers have their own different understanding, have their own different definitions. The cloud computing platform they offer is also vastly different. When it comes to cloud computing, people always think of these things: high scalability (scalability), cost savings (saving), on-demand (use on Demand), and so on. Let's give it a few of the myriad things that cloud computing brings ...