实验目的: 1 熟悉hadoop集群以及hadoop起源历史。 2 了解hadoop使用范围以及所需基础知识。 3 安装hadoop 1.x 实验版本。 实验设备以及所用软件: 笔记本电脑、VMware、Centos6.3(3台虚拟机) 实验过程: 1、 启动VMware-准备好三台虚拟机的安装,这里使用
实验目的:
1 熟悉hadoop集群以及hadoop起源历史。
2 了解hadoop使用范围以及所需基础知识。
3 安装hadoop 1.x 实验版本。
实验设备以及所用软件:
笔记本电脑、VMware、Centos6.3(3台虚拟机)
实验过程:
1、 启动VMware-准备好三台虚拟机的安装,这里使用的是Centos6.3简易版的安装,三台机器分别命名为master,slave,slave1,开启gpm服务,启动三台虚拟机,使用ifconfig命令查得master,slave,slave1的ip地址分别为192.168.1.112,192.168.1.111,192.168.1.109。在root权限下使用chkconfigiptables off命令关闭防火墙。
2、 ssh 免密码登陆普通用户模式下,首先ssh ip地址测试三台机子能否互相通信,若不能通信则检查ip是否在同一个网段,cd命令返回根目录,三台都使用命令
ssh-keygen –t rsa,命令行ls –a,检查根目录下是否有.ssh这个目录,cd .ssh进入目录下,ls -a检查是否有id_rsa.pub和id_rsa。接下来,通过命令
scp ./id_rsa.pub hadoop@ip:/home/hadoop/.ssh/authorized_keys,鼠标命令将三台机子的公钥全部复制粘贴进authorized-keys,放到每台虚拟系统的.ssh目录下,然后通过ssh ip三台机子检测是否成功。注意:这里ssh ip成功的前提条件是用户名相同,不然使用ssh 用户名@ip才能成功,用户名相同也是这个实验成功的条件。
3.网上下载jdk1.8.0_05和hadoop1.2.1版本到master上,使用tar –xzvf jdk包或hadoop包,这是个漫长的等待过程,大家耐心等待。
4.接下来修改hadoop相关文件命令,在根目录时,cd hadoop1.2.1,cd conf,
vi hadoop-env.sh,修改jdk所在目录位置。
vi core-site.xml
vi mapred-site.xml
vi hdfs-site.xml
vi masters
vi slaves
5.把hadoop1.2.1以及jdk1.8.0_05发送到另外两台机器上(scp -r ./文件名 用户名@ip:/位置)
6.三台机器中修改hosts文件,vi /etc/hosts,把ip地址跟用户名写入文件,然后ping slave1,ping slave,ping master,检测hosts文件是否有错误。
进入hadoop1.2.1文件(cd hadoop1.2.1),执行bin/start-all.sh成功!!!
7.最后去jdk里面的jpm服务里面检测,成功!

In database optimization, indexing strategies should be selected according to query requirements: 1. When the query involves multiple columns and the order of conditions is fixed, use composite indexes; 2. When the query involves multiple columns but the order of conditions is not fixed, use multiple single-column indexes. Composite indexes are suitable for optimizing multi-column queries, while single-column indexes are suitable for single-column queries.

To optimize MySQL slow query, slowquerylog and performance_schema need to be used: 1. Enable slowquerylog and set thresholds to record slow query; 2. Use performance_schema to analyze query execution details, find out performance bottlenecks and optimize.

MySQL and SQL are essential skills for developers. 1.MySQL is an open source relational database management system, and SQL is the standard language used to manage and operate databases. 2.MySQL supports multiple storage engines through efficient data storage and retrieval functions, and SQL completes complex data operations through simple statements. 3. Examples of usage include basic queries and advanced queries, such as filtering and sorting by condition. 4. Common errors include syntax errors and performance issues, which can be optimized by checking SQL statements and using EXPLAIN commands. 5. Performance optimization techniques include using indexes, avoiding full table scanning, optimizing JOIN operations and improving code readability.

MySQL asynchronous master-slave replication enables data synchronization through binlog, improving read performance and high availability. 1) The master server record changes to binlog; 2) The slave server reads binlog through I/O threads; 3) The server SQL thread applies binlog to synchronize data.

MySQL is an open source relational database management system. 1) Create database and tables: Use the CREATEDATABASE and CREATETABLE commands. 2) Basic operations: INSERT, UPDATE, DELETE and SELECT. 3) Advanced operations: JOIN, subquery and transaction processing. 4) Debugging skills: Check syntax, data type and permissions. 5) Optimization suggestions: Use indexes, avoid SELECT* and use transactions.

The installation and basic operations of MySQL include: 1. Download and install MySQL, set the root user password; 2. Use SQL commands to create databases and tables, such as CREATEDATABASE and CREATETABLE; 3. Execute CRUD operations, use INSERT, SELECT, UPDATE, DELETE commands; 4. Create indexes and stored procedures to optimize performance and implement complex logic. With these steps, you can build and manage MySQL databases from scratch.

InnoDBBufferPool improves the performance of MySQL databases by loading data and index pages into memory. 1) The data page is loaded into the BufferPool to reduce disk I/O. 2) Dirty pages are marked and refreshed to disk regularly. 3) LRU algorithm management data page elimination. 4) The read-out mechanism loads the possible data pages in advance.

MySQL is suitable for beginners because it is simple to install, powerful and easy to manage data. 1. Simple installation and configuration, suitable for a variety of operating systems. 2. Support basic operations such as creating databases and tables, inserting, querying, updating and deleting data. 3. Provide advanced functions such as JOIN operations and subqueries. 4. Performance can be improved through indexing, query optimization and table partitioning. 5. Support backup, recovery and security measures to ensure data security and consistency.


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