MySQL数据库实例参数对比脚本

如何对比两个MySQL实例的参数情况，生产中常会有这样的需求，最近写了个python脚本，可基本实现该需求。

脚本

#!/usr/bin/python
import MySQLdb,sys
def fetch_variables(ip,user,passwd,port,variable=False):
    # Open database connection
    try:
        db = MySQLdb.connect(host=ip, user=user,passwd=passwd,port=port)
    except Exception,e:
        print e
        exit()
    # prepare a cursor object using cursor() method
    cursor = db.cursor()
    if not variable:
        sql = 'show variables'
    else:
        sql= "show variables like '%"+variable+"%'"
    try:
        # execute SQL query using execute() method.
        cursor.execute(sql)
        # Fetch all the rows in a list of lists.
        results = cursor.fetchall()
        dict={}
        for row in results:
            dict[row[0]]=row[1]
    except:
       print "Error: unable to fecth data"
    return dict
def dict_to_set(dict):
    return set(dict.keys())

def main():
    if len(sys.argv)!=3 and  len(sys.argv)!=4:
        print 'Usage:',sys.argv[0],'ip:port nip:nport var'
        exit()
    user = 'root'
    password = ''
    ip, port = sys.argv[1].split(':')
    nip,nport=sys.argv[2].split(':')
    if len(sys.argv)==3:
        variable=False
    else:
        variable=sys.argv[3]
    dict = fetch_variables(ip, user, password, int(port),variable)
    ndict = fetch_variables(nip, user, password, int(nport),variable)
    set=dict_to_set(dict)
    nset=dict_to_set(ndict)
    same_variables=set.intersection(nset)
    for variable in same_variables:
        if dict[variable] != ndict[variable]:
            print variable,':',dict[variable],'|',ndict[variable]
if __name__=='__main__':
    main()

执行方式

输入：ip:port nip:nport var
功能：如果var为空，表示比较所有参数

带实例参数时，执行结果如下：

[root@mysql-server1 ~]# python diff_parameters.py 192.168.244.145:3306 192.168.244.146:3306 general_log_file
general_log_file : /var/lib/mysql/mysql-server1.log | /var/lib/mysql/keepalived01.log

不带实例参数时，执行结果如下：

[root@mysql-server1 ~]# python diff_parameters.py 192.168.244.145:3306 192.168.244.146:3306
version : 5.6.26-log | 5.6.26
log_bin_index : /var/lib/mysql/mysql-bin.index |
log_bin_basename : /var/lib/mysql/mysql-bin |
pseudo_thread_id : 9 | 104
slow_query_log_file : /var/lib/mysql/mysql-server1-slow.log | /var/lib/mysql/keepalived01-slow.log
server_id : 1 | 2
hostname : mysql-server1 | keepalived01
timestamp : 1462931171.666154 | 1462931171.957681
log_bin : ON | OFF
general_log_file : /var/lib/mysql/mysql-server1.log | /var/lib/mysql/keepalived01.log
max_binlog_size : 134217728 | 1073741824
server_uuid : c063ba6f-aee7-11e5-820e-000c29b05336 | 959bf641-b9e7-11e5-89c7-000c294c5ed4

输出结果解读：

第一列是实例参数，第二列和第三列用“|”隔开，其中第二列是第一个实例的参数值，第三列是第二个实例的参数值。

脚本解读

函数def fetch_variables(ip,user,passwd,port,variable=False)是从数据库中获取实例参数及值。variable=False的作用是来处理var为空和var不为空时的情况。

函数def dict_to_set(dict)是将字典转化为集合，这样对于字典的比较可以转为为集合来操作。