前几篇文章讲述了 HBase的安装、Hbase命令和API的使用、HBase简单的优化技巧，《HBase入门篇4》这篇文章是讲述把HBase的数据放在HDFS上的点滴过程。目前对与HBase我是一个绝对的新手，如果在文章中有任何我理解有错误的地方请各位指正，谢谢。 Ok，进行正题
前几篇文章讲述了 HBase的安装、Hbase命令和API的使用、HBase简单的优化技巧，《HBase入门篇4》这篇文章是讲述把HBase的数据放在HDFS上的点滴过程。目前对与HBase我是一个绝对的新手，如果在文章中有任何我理解有错误的地方请各位指正，谢谢。
Ok，进行正题 ………
在HBase中创建的一张表可以分布在多个Hregion，也就说一张表可以被拆分成多块，每一块称我们呼为一个Hregion。每个Hregion会保 存一个表里面某段连续的数据，用户创建的那个大表中的每个Hregion块是由Hregion服务器提供维护，访问Hregion块是要通过 Hregion服务器，而一个Hregion块对应一个Hregion服务器，一张完整的表可以保存在多个Hregion 上。HRegion Server 与Region的对应关系是一对多的关系。每一个HRegion在物理上会被分为三个部分：Hmemcache(缓存)、Hlog(日志)、HStore(持久层)。
上述这些关系在我脑海中的样子，如图所示：
1.HRegionServer、HRegion、Hmemcache、Hlog、HStore之间的关系，如图所示：
2.HBase表中的数据与HRegionServer的分布关系，如图所示：
HBase读数据
HBase读取数据优先读取HMemcache中的内容，如果未取到再去读取Hstore中的数据，提高数据读取的性能。
HBase写数据
HBase写入数据会写到HMemcache和Hlog中，HMemcache建立缓存，Hlog同步Hmemcache和Hstore的事务日志，发起Flush Cache时，数据持久化到Hstore中，并清空HMemecache。
客户端访问这些数据的时候通过Hmaster ，每个 Hregion 服务器都会和Hmaster 服务器保持一个长连接，Hmaster 是HBase分布式系统中的管理者，他的主要任务就是要告诉每个Hregion 服务器它要维护哪些Hregion。用户的这些都数据可以保存在Hadoop 分布式文件系统上。 如果主服务器Hmaster死机，那么整个系统都会无效。下面我会考虑如何解决Hmaster的SPFO的问题，这个问题有点类似Hadoop的SPFO 问题一样只有一个NameNode维护全局的DataNode，HDFS一旦死机全部挂了，也有人说采用Heartbeat来解决这个问题，但我总想找出 其他的解决方案，多点时间，总有办法的。
昨天在hadoop-0.21.0、hbase-0.20.6的环境中折腾了很久，一直报错，错误信息如下：
Exception in thread "main" java.io.IOException: Call to localhost/serv6:9000 failed on local exception: java.io.EOFException
10/11/10 15:34:34 ERROR master.HMaster: Can not start master
java.lang.reflect.InvocationTargetException
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:39)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:27)
at java.lang.reflect.Constructor.newInstance(Constructor.java:513)
at org.apache.hadoop.hbase.master.HMaster.doMain(HMaster.java:1233)
at org.apache.hadoop.hbase.master.HMaster.main(HMaster.java:1274)
死活连接不上HDFS，也无法连接HMaster，郁闷啊。
我想想啊，慢慢想，我眼前一亮 java.io.EOFException 这个异常，是不是有可能是RPC 协定格式不一致导致的？也就是说服务器端和客户端的版本不一致的问题？换了一个HDFS的服务器端以后，一切都好了，果然是版本的问题，最后采用 hadoop-0.20.2 搭配hbase-0.20.6 比较稳当。
最后的效果如图所示：
查看大图请点击这里， 上图的一些文字说明：
1.hadoop版本是0.20.2 ,
2.hbase版本是0.20.6,
3.在hbase中创建了一张表 tab1，退出hbase shell环境,
4.用hadoop命令查看，文件系统中的文件果然多了一个刚刚创建的tab1目录,
以上这张图片说明HBase在分布式文件系统Apache HDFS中运行了。
相关文章：
Hbase入门6 -白话MySQL(RDBMS)与HBase之间
Lily-建立在HBase上的分布式搜索
MySQL向Hive/HBase的迁移工具
HBase入门5(集群) -压力分载与失效转发
Hive入门3–Hive与HBase的整合
HBase入门篇4
HBase入门篇3
HBase入门篇2-Java操作HBase例子
HBase入门篇
基于Hbase存储的分布式消息(IM)系统-JABase
–end–
How do you create and manage user accounts in MySQL?Apr 22, 2025 pm 06:05 PMThe steps to create and manage user accounts in MySQL are as follows: 1. Create a user: Use CREATEUSER'newuser'@'localhost'IDENTIFIEDBY'password'; 2. Assign permissions: Use GRANTSELECT, INSERT, UPDATEONmydatabase.TO'newuser'@'localhost'; 3. Fix permission error: Use REVOKEALLPRIVILEGESONmydatabase.FROM'newuser'@'localhost'; then reassign permissions; 4. Optimization permissions: Use SHOWGRA
How does MySQL differ from Oracle?Apr 22, 2025 pm 05:57 PMMySQL is suitable for rapid development and small and medium-sized applications, while Oracle is suitable for large enterprises and high availability needs. 1) MySQL is open source and easy to use, suitable for web applications and small and medium-sized enterprises. 2) Oracle is powerful and suitable for large enterprises and government agencies. 3) MySQL supports a variety of storage engines, and Oracle provides rich enterprise-level functions.
What are the disadvantages of using MySQL compared to other relational databases?Apr 22, 2025 pm 05:49 PMThe disadvantages of MySQL compared to other relational databases include: 1. Performance issues: You may encounter bottlenecks when processing large-scale data, and PostgreSQL performs better in complex queries and big data processing. 2. Scalability: The horizontal scaling ability is not as good as Google Spanner and Amazon Aurora. 3. Functional limitations: Not as good as PostgreSQL and Oracle in advanced functions, some functions require more custom code and maintenance.
How do you perform a JOIN operation in MySQL?Apr 22, 2025 pm 05:41 PMMySQL supports four JOIN types: INNERJOIN, LEFTJOIN, RIGHTJOIN and FULLOUTERJOIN. 1.INNERJOIN is used to match rows in two tables and return results that meet the criteria. 2.LEFTJOIN returns all rows in the left table, even if the right table does not match. 3. RIGHTJOIN is opposite to LEFTJOIN and returns all rows in the right table. 4.FULLOUTERJOIN returns all rows in the two tables that meet or do not meet the conditions.
How does MySQL's performance compare to other RDBMS under high load?Apr 22, 2025 pm 05:37 PMMySQL's performance under high load has its advantages and disadvantages compared with other RDBMSs. 1) MySQL performs well under high loads through the InnoDB engine and optimization strategies such as indexing, query cache and partition tables. 2) PostgreSQL provides efficient concurrent read and write through the MVCC mechanism, while Oracle and Microsoft SQLServer improve performance through their respective optimization strategies. With reasonable configuration and optimization, MySQL can perform well in high load environments.
Explain the InnoDB Buffer Pool and its importance for performance.Apr 19, 2025 am 12:24 AMInnoDBBufferPool reduces disk I/O by caching data and indexing pages, improving database performance. Its working principle includes: 1. Data reading: Read data from BufferPool; 2. Data writing: After modifying the data, write to BufferPool and refresh it to disk regularly; 3. Cache management: Use the LRU algorithm to manage cache pages; 4. Reading mechanism: Load adjacent data pages in advance. By sizing the BufferPool and using multiple instances, database performance can be optimized.
MySQL vs. Other Programming Languages: A ComparisonApr 19, 2025 am 12:22 AMCompared with other programming languages, MySQL is mainly used to store and manage data, while other languages such as Python, Java, and C are used for logical processing and application development. MySQL is known for its high performance, scalability and cross-platform support, suitable for data management needs, while other languages have advantages in their respective fields such as data analytics, enterprise applications, and system programming.
Learning MySQL: A Step-by-Step Guide for New UsersApr 19, 2025 am 12:19 AMMySQL is worth learning because it is a powerful open source database management system suitable for data storage, management and analysis. 1) MySQL is a relational database that uses SQL to operate data and is suitable for structured data management. 2) The SQL language is the key to interacting with MySQL and supports CRUD operations. 3) The working principle of MySQL includes client/server architecture, storage engine and query optimizer. 4) Basic usage includes creating databases and tables, and advanced usage involves joining tables using JOIN. 5) Common errors include syntax errors and permission issues, and debugging skills include checking syntax and using EXPLAIN commands. 6) Performance optimization involves the use of indexes, optimization of SQL statements and regular maintenance of databases.
Hot AI Tools
Undresser.AI Undress
AI-powered app for creating realistic nude photos
AI Clothes Remover
Online AI tool for removing clothes from photos.
Undress AI Tool
Undress images for free
Clothoff.io
AI clothes remover
Video Face Swap
Swap faces in any video effortlessly with our completely free AI face swap tool!
Hot Article
Hot Tools
Atom editor mac version download
The most popular open source editor
SublimeText3 English version
Recommended: Win version, supports code prompts!
mPDF
mPDF is a PHP library that can generate PDF files from UTF-8 encoded HTML. The original author, Ian Back, wrote mPDF to output PDF files "on the fly" from his website and handle different languages. It is slower than original scripts like HTML2FPDF and produces larger files when using Unicode fonts, but supports CSS styles etc. and has a lot of enhancements. Supports almost all languages, including RTL (Arabic and Hebrew) and CJK (Chinese, Japanese and Korean). Supports nested block-level elements (such as P, DIV),
DVWA
Damn Vulnerable Web App (DVWA) is a PHP/MySQL web application that is very vulnerable. Its main goals are to be an aid for security professionals to test their skills and tools in a legal environment, to help web developers better understand the process of securing web applications, and to help teachers/students teach/learn in a classroom environment Web application security. The goal of DVWA is to practice some of the most common web vulnerabilities through a simple and straightforward interface, with varying degrees of difficulty. Please note that this software
MinGW - Minimalist GNU for Windows
This project is in the process of being migrated to osdn.net/projects/mingw, you can continue to follow us there. MinGW: A native Windows port of the GNU Compiler Collection (GCC), freely distributable import libraries and header files for building native Windows applications; includes extensions to the MSVC runtime to support C99 functionality. All MinGW software can run on 64-bit Windows platforms.
