熟悉常用的HBase操作，编写MapReduce作业

Posted 2020-11-03 李文辉

1

***创建数据表studen
   其中info,course分别为表studen的两个列族，
info存储学生个人信息——学号、姓名、性别、年龄
course 则存储课程信息***
create \'studen\',\'info\',\'course\'



接着添加学号为2015001的学生信息
put \'studen\',\'001\',\'info:S_No\',\'2015001\'
此行代码插入一个行健为001的数据，且在列族info中添加一个列S_No,值为2015001。同时由于Hbase一次只能添加一个列数据，所以下面继续添加2015001其他信息
put \'studen\',\'001\',\'info:S_Name\',\'Zhangsan\'
put \'studen\',\'001\',\'info:S_Sex\',\'male\'
put \'studen\',\'001\',\'info:S_Age\',\'23\'

2

3

cd /home/hadoop/wc
sudo gedit mapper.py

import sys
for i in stdin:
    i = i.strip()
    words = i.split()
    for word in words:
    print \'%s\\t%s\' % (word,1)

from operator import itemgetter
import sys

current_word = None
current_count = 0
word = None

for i in stdin:
    i = i.strip()
    word, count = i.split(\'\\t\',1)
    try:
    count = int(count)
    except ValueError:
    continue

    if current_word == word:
    current_count += count 
    else:
    if current_word:
        print \'%s\\t%s\' % (current_word, current_count)
    current_count = count
    current_word = word

if current_word == word:
    print \'%s\\t%s\' % (current_word, current_count)

cd /home/hadoop/wc
sudo gedit reducer.py

chmod a+x /home/hadoop/mapper.py


#上传
cd  /home/hadoop/wc
wget http://www.gutenberg.org/files/5000/5000-8.txt
wget http://www.gutenberg.org/cache/epub/20417/pg20417.txt

#下载
cd /usr/hadoop/wc
hdfs dfs -put /home/hadoop/hadoop/gutenberg/*.txt /user/hadoop/input