ourmysql博客中提供了 《大表删除数据的思路》,对于大表依据主键删除的思路是必须的，删除几千万的数据还算是比较简单的，如果你的数据库中的表高达数百亿条记录 ，删除其中的几十亿，就需要考虑可用性的问题了。上述文中的 利用生成的文本方式有些不妥。

我的方法是利用存储过程,游标，先根据条件获取要删除的主键，然后依据主键删除，考虑到删除50亿条记录耗费将近7天的时间(事后得出)，必须后台执行。使用python 工具写一个脚本，可以针对多个服务器进行并行操作。

1 在各个服务器上创建存过！

delimiter //

CREATE  PROCEDURE `proc_del_tab`(in com_num int , in push_time datetime )

begin

declare curid bigint ;

DECLARE rowid bigint ;

declare no_more_departments int ;

declare curs cursor for

select id

from

tab

WHERE

v3 < push_time ;

DECLARE CONTINUE HANDLER FOR NOT FOUND SET no_more_departments = 1;

SET no_more_departments=0;

set rowid = 1 ;

set autocommit = 0 ;

open curs ;

REPEAT

fetch curs into curid ;

delete from tab where id = curid ;

set rowid = rowid + 1 ;

if rowid % com_num = 0

then

commit;

end if ;

UNTIL no_more_departments

END REPEAT;

commit ;

close curs ;

end;

//

delimiter ;

2 部署python 脚本：

#!/usr/bin/env python

from MySQLdb import *

import sys

import threading

import time

import os

def now() :

#return str('2011-01-31 00:00:00')

return str( time.strftime( '%Y-%m-%d %H:%M:%S' , time.localtime() ) )

def log( strs , logs ) :

f = file( logs , 'a' , 0 )

f.write( now() + ' ' + str(strs) + '\n' )

f.close()

def delining( cur , logs ) :

sql = "SET SQL_LOG_BIN=0"

try :

cur['dsn'].execute( sql )

except Exception , e :

log( 'Set SQL_LOG_BIN OFF' + str(e) , logs )

sql = "call proc_del_tab_yang( 3000 , '%s' )" % ('2011-01-31 00:00:00')

log( 'starting process %s' % ( cur['addr'] ) , logs )

try :

cur['dsn'].execute( sql )

except Exception , e :

log( 'Execute Procedure ' + str(e) , logs )

sql = "SET SQL_LOG_BIN=1"

try :

cur['dsn'].execute( sql )

except Exception , e :

log( 'Set SQL_LOG_BIN ON' + str(e) , logs )

log( 'process %s End' % ( cur['addr'] ) , logs )

def main() :

logs = "/root/yangql/python/del_test_tab.log"

server_list=['10.250.7.110']

luser="yang"

lpasswd="yang"

con = []

for addr in server_list :

cons = None

try :

cons = connect( host = addr , user = luser , passwd = lpasswd , port = 3307 , db = 'newcloudapp' )

except Exception , e :

log( 'On Connect %s ' % ( addr ) + str(e) , logs )

continue

con.append(  { 'dsn':cons , 'addr':addr } )

cur = []

for cons in con :

try :

cur.append( { 'dsn':cons['dsn'].cursor( cursorclass = cursors.DictCursor ) , 'addr':cons['addr'] } )

except Exception , e :

log( 'On Cusros %s ' % ( cons['addr'] ) + str(e)  , logs )

continue

thpool = []

for curs in cur :

th = threading.Thread(target = delining ,args=( curs , logs ) )

thpool.append( th )

for th in thpool :

th.start()

for th in thpool :

threading.Thread.join( th )

while True :

if threading.activeCount() < 2 :

break

else :

time.sleep(1)

continue

for curs in cur :

try :

curs['dsn'].close()

except Exception , e :

log( 'On Close Cusros %s ' % ( curs['addr'] ) + str(e)  , logs )

continue

for cons in con :

try :

cons['dsn'].close()

except Exception , e :

log( 'On Close Connect %s ' % ( str(e)  ) , logs )

continue

if __name__ == '__main__' :

main()

欢迎大家提出更好的方法。。