实例讲解Hadoop中的hive查询(Python语言实现)

条件，假设配置好了Hadoop和hive，并可以正常运行

首先，要外部查询hive，你需要安装thrift和fb303，或许有别的办法，但我实际应用过程中看来，这是最简单的途径。hive本身提供了thrift的接口。文件在hive解压缩后如下路径中

hive/hive-0.7.1/src/service/if/hive_service.thrift

然后复制四个文件

metastore/if/hive_metastore.thrift

src/service/if/hive_service.thrift

ql/if/queryplan.thrift

和

thrift源码下fb303中的fb303.thrift。

编辑hive_service.thrift，将其中include其他三个文件的路径修改为正确的路径。保存退出，运行thrift

#thrift -r --gen Python hive_service.thrift

将生成的python放入/usr/lib/python/site-packages下，然后编写如下脚本

#!/usr/bin/python
#-*-coding:UTF-8 -*-
import sys
import os
import string
import re
import MySQLdb

from hive_service import ThriftHive
from hive_service.ttypes import HiveServerException
from thrift import Thrift
from thrift.transport import TSocket
from thrift.transport import TTransport
from thrift.protocol import TBinaryProtocol

def hiveExe(hsql,dbname):
#定义hive查询函数
                try:
                                transport = TSocket.TSocket('192.168.10.1', 10000)
                                transport = TTransport.TBufferedTransport(transport)
                                protocol = TBinaryProtocol.TBinaryProtocol(transport)

                                client = ThriftHive.Client(protocol)
                                transport.open()

                                client.execute('ADD jar /opt/modules/hive/hive-0.7.1/lib/hive-contrib-0.7.1.jar')

                                client.execute("use "+dbname)
                                row = client.fetchOne()
                                #使用库名，只需一次fetch，用fetchOne

                                client.execute(hsql)
                                return client.fetchAll()
                                #查询所有数据，用fetchAll()

                                transport.close()

                except Thrift.TException, tx:
                                print '%s' % (tx.message)

def mysqlExe(sql):
                try:
                                conn = MySQLdb.connect(user="test",passwd="test123",host="127.0.0.1",db="active2_ip",port=5029)
                except Exception,data:
                                print "Could not connect to MySQL server.:",data
                try:
                                cursor = conn.cursor()
                                cursor.execute(sql)
                                return row
                                cursor.commit()
                                cursor.close()
                                conn.close()
                except Exception,data:
                                print "Could not Fetch anything:",data

dbname = "active2"
date = os.popen("date -d '1 day ago' +%Y%m%d").read().strip()
#shell方式取昨天日期，读取并去前后\n
date.close()

sql = "create table IF NOT EXISTS "+dbname+"_group_ip_"+date+" like "+dbname+"_group_ip;load data infile '/tmp/"+dbname+"_"+date+".csv' into table "+dbname+"_group_ip_"+date+" FIELDS TERMINATED BY ','"
#以模板表创建日期表，并load data到该表中

hsql = "insert overwrite local directory '/tmp/"+dbname+"_"+date+"' select count(version) as vc,stat_hour,type,version,province,city,isp from "+dbname+"_"+date+" group by province,city,version,type,stat_hour,isp"
#hive查询，并将查询结果导出到本地/tmp/active2_20111129目录下，可能生成多个文件

hiveExe(hsql, dbname)
#执行查询

os.system("sudo cat /tmp/"+dbname+"_"+date+"/* > /tmp/tmplog ")
#将多个文件通过shell合并为一个文件tmplog

file1 = open("/tmp/tmplog", 'r')
#打开合并后的临时文件
file2 = open("/tmp/"+dbname+"_"+date+".csv",'w')
#打开另一个文件，做文字替换。因为hive导出结果，其分隔符为特殊字符。所以需要做替换，格式为csv，故用逗号分隔
sep = ','
for line in file1:
                tmp = line[:-1].split('\x01')
                #hive导出文件分隔符为ascii中的001，\x01是16进制，但其实也就是十进制的1
                replace = sep.join(tmp)
                file2.write(replace+"\n")


file1.close()
file2.close()

os.system("sudo rm -f /tmp/tmplog")
#删除临时的tmplog

mysqlExe(sql)
#执行mysql查询，创建表和加载数据。
os.system("sudo rm -f /tmp/"+dbname+"_"+date)