对于mysql加索引，删除索引，添加列，删除列，修改列顺序的最佳办法测试

Posted 2020-10-13 黄海的编程知识世界

1、首先进行数据训的XltraBackup备份，有备无患，切记切记！

2、
mysql -uroot -pD********
-- 导出csv文件
use dsideal_db;

MariaDB [dsideal_db]> SELECT * from t_resource_info INTO OUTFILE "/usr/local/mysql/t_resource_info.txt" FIELDS TERMINATED BY ‘,‘ OPTIONALLY ENCLOSED BY ‘"‘ LINES TERMINATED BY ‘\n‘;
Query OK, 1582463 rows affected (29.97 sec)

3、切分csv文件，这样分批导入更快，更方便，参考这里：http://www.nowamagic.net/librarys/veda/detail/2495，但是不能使用按容量啊，一定要按行。说日志太大拿不回来的，罚面壁一小时！
mkdir /usr/local/huanghai -p
split -a 2 -d -l 50000 /usr/local/mysql/t_resource_info.txt /usr/local/huanghai/prefix
2-3秒吧

3、清空原表，修改字段，反正有备份，不怕的
　　truncate t_resource_info;
　　alter table t_resource_info add huanghai_test int;

4、优化环境配置，准备开始导入
SET autocommit=0;
SET unique_checks=0;
SET foreign_key_checks=0;
set sql_log_bin=0;

SET @innodb_additional_mem_pool_size=26214400;
set @innodb_buffer_pool_size=1073741824;
set @innodb_log_buffer_size=8388608;
set @innodb_log_file_size=268435456;


load data infile ‘/usr/local/huanghai/prefix00‘ IGNORE into table dsideal_db.t_resource_info_huanghai fields terminated by ‘,‘ enclosed by ‘"‘;
load data infile ‘/usr/local/huanghai/prefix01‘ IGNORE into table dsideal_db.t_resource_info_huanghai fields terminated by ‘,‘ enclosed by ‘"‘;
load data infile ‘/usr/local/huanghai/prefix02‘ IGNORE into table dsideal_db.t_resource_info_huanghai fields terminated by ‘,‘ enclosed by ‘"‘;
load data infile ‘/usr/local/huanghai/prefix03‘ IGNORE into table dsideal_db.t_resource_info_huanghai fields terminated by ‘,‘ enclosed by ‘"‘;
load data infile ‘/usr/local/huanghai/prefix04‘ IGNORE into table dsideal_db.t_resource_info_huanghai fields terminated by ‘,‘ enclosed by ‘"‘;
load data infile ‘/usr/local/huanghai/prefix05‘ IGNORE into table dsideal_db.t_resource_info_huanghai fields terminated by ‘,‘ enclosed by ‘"‘;
load data infile ‘/usr/local/huanghai/prefix06‘ IGNORE into table dsideal_db.t_resource_info_huanghai fields terminated by ‘,‘ enclosed by ‘"‘;
load data infile ‘/usr/local/huanghai/prefix07‘ IGNORE into table dsideal_db.t_resource_info_huanghai fields terminated by ‘,‘ enclosed by ‘"‘;
load data infile ‘/usr/local/huanghai/prefix08‘ IGNORE into table dsideal_db.t_resource_info_huanghai fields terminated by ‘,‘ enclosed by ‘"‘;
load data infile ‘/usr/local/huanghai/prefix09‘ IGNORE into table dsideal_db.t_resource_info_huanghai fields terminated by ‘,‘ enclosed by ‘"‘;
load data infile ‘/usr/local/huanghai/prefix10‘ IGNORE into table dsideal_db.t_resource_info_huanghai fields terminated by ‘,‘ enclosed by ‘"‘;
load data infile ‘/usr/local/huanghai/prefix11‘ IGNORE into table dsideal_db.t_resource_info_huanghai fields terminated by ‘,‘ enclosed by ‘"‘;
load data infile ‘/usr/local/huanghai/prefix12‘ IGNORE into table dsideal_db.t_resource_info_huanghai fields terminated by ‘,‘ enclosed by ‘"‘;
load data infile ‘/usr/local/huanghai/prefix13‘ IGNORE into table dsideal_db.t_resource_info_huanghai fields terminated by ‘,‘ enclosed by ‘"‘;
load data infile ‘/usr/local/huanghai/prefix14‘ IGNORE into table dsideal_db.t_resource_info_huanghai fields terminated by ‘,‘ enclosed by ‘"‘;
load data infile ‘/usr/local/huanghai/prefix15‘ IGNORE into table dsideal_db.t_resource_info_huanghai fields terminated by ‘,‘ enclosed by ‘"‘;
load data infile ‘/usr/local/huanghai/prefix16‘ IGNORE into table dsideal_db.t_resource_info_huanghai fields terminated by ‘,‘ enclosed by ‘"‘;
load data infile ‘/usr/local/huanghai/prefix17‘ IGNORE into table dsideal_db.t_resource_info_huanghai fields terminated by ‘,‘ enclosed by ‘"‘;
load data infile ‘/usr/local/huanghai/prefix18‘ IGNORE into table dsideal_db.t_resource_info_huanghai fields terminated by ‘,‘ enclosed by ‘"‘;
load data infile ‘/usr/local/huanghai/prefix19‘ IGNORE into table dsideal_db.t_resource_info_huanghai fields terminated by ‘,‘ enclosed by ‘"‘;


commit;

5、恢复现场
SET autocommit=1;
SET unique_checks=1;
SET foreign_key_checks=1;
set sql_log_bin=1;

6、建议使用python3进行开发一个程序，这样方便串连起来，这是我目前能想到的最好办法，基本无风险，速度上基本能利用磁盘的最大IO，不建议采用修改frm等暴力办法，那个对于最后面追加字段的可能还行，对于字段在中间的
可能就是灾难，而且没有办法程序化，这个办法是用python3开发起来，基本无困难。