mysqldump 的一个参数 --compact
官网给出的说法是这样:
--compact
Produce more compact output. This option enables the --skip-add-drop-table, --skip-addlocks, --skip-comments, --skip-disable-keys, and --skip-set-charset options.
大概意思就是让导出的脚本里面取消一些注释和不必要的sql.
下面这这几行就是加了--compact参数后的抬头几行....
-- CHANGE MASTER TO MASTER_LOG_FILE='mysql-bin.000503', MASTER_LOG_POS=107;
CREATE DATABASE /*!32312 IF NOT EXISTS*/ `test` /*!40100 DEFAULT CHARACTER SET utf8 */;
USE `test`;
/*!40101 SET @saved_cs_client = @@character_set_client */;
/*!40101 SET character_set_client = utf8 */;
CREATE TABLE `account_for_withdraw` (
`account_id` varchar(30) NOT NULL COMMENT '资金流水号',
`withdraw_id` varchar(30) DEFAULT NULL COMMENT '提现流水号',
`biz_no` varchar(20) NOT NULL COMMENT '交易流水号',
`withdraw_time` int(11) DEFAULT NULL COMMENT '延迟提现时间（每天定时任务递减）',
下面在来比较下不加--compact导出后的脚本抬头几行:
-- MySQL dump 10.13 Distrib 5.5.33, for Linux (x86_64)
--
-- Host: localhost Database: test
-- ------------------------------------------------------
-- Server version 5.5.33-log
/*!40101 SET @OLD_CHARACTER_SET_CLIENT=@@CHARACTER_SET_CLIENT */;
/*!40101 SET @OLD_CHARACTER_SET_RESULTS=@@CHARACTER_SET_RESULTS */;
/*!40101 SET @OLD_COLLATION_CONNECTION=@@COLLATION_CONNECTION */;
/*!40101 SET NAMES utf8 */;
/*!40103 SET @OLD_TIME_ZONE=@@TIME_ZONE */;
/*!40103 SET TIME_ZONE='+00:00' */;
/*!40014 SET @OLD_UNIQUE_CHECKS=@@UNIQUE_CHECKS, UNIQUE_CHECKS=0 */;
/*!40014 SET @OLD_FOREIGN_KEY_CHECKS=@@FOREIGN_KEY_CHECKS, FOREIGN_KEY_CHECKS=0 */;
/*!40101 SET @OLD_SQL_MODE=@@SQL_MODE, SQL_MODE='NO_AUTO_VALUE_ON_ZERO' */;
/*!40111 SET @OLD_SQL_NOTES=@@SQL_NOTES, SQL_NOTES=0 */;
--
-- Position to start replication or point-in-time recovery from
--
-- CHANGE MASTER TO MASTER_LOG_FILE='mysql-bin.000508', MASTER_LOG_POS=107;
--
-- Current Database: `test`
--
CREATE DATABASE /*!32312 IF NOT EXISTS*/ `test` /*!40100 DEFAULT CHARACTER S
USE `test`;
--
-- Table structure for table `account_for_withdraw`
--
DROP TABLE IF EXISTS `account_for_withdraw`;
/*!40101 SET @saved_cs_client = @@character_set_client */;
/*!40101 SET character_set_client = utf8 */;
CREATE TABLE `account_for_withdraw` (
`account_id` varchar(30) NOT NULL COMMENT '资金流水号',
`withdraw_id` varchar(30) DEFAULT NULL COMMENT '提现流水号',
`biz_no` varchar(20) NOT NULL COMMENT '交易流水号',
`withdraw_time` int(11) DEFAULT NULL COMMENT '延迟提现时间（每天定时任务递减）',
两相比较,就可以看出,加了compact后的脚本的确更紧凑了...少了很多注释...
最开始我以为是好事,毕竟这些注释对一相同环境来说,没什么大的影响..可后来在线上一次操作,导致了大问题产生...
这里,只记录我这次操作失误有关的参数...其他的参数,另请参考官网.
/*!40103 SET @OLD_TIME_ZONE=@@TIME_ZONE */;
/*!40103 SET TIME_ZONE='+00:00' */;
.......(中间建表啊,插入sql啊忽略)
/*!40103 SET TIME_ZONE=@OLD_TIME_ZONE */;
我的失误就是由这三行造成的....在加了compact参数后,是没有这三行参数的...
失误是什么勒? 时间...时间相差8小时....都知道了吧....刚好8个时区...我们是北京时间...
先不说原因和问题,,先做一个测试:
mysql> desc test;
+-------+-------------+------+-----+-------------------+-----------------------------+
| Field | Type | Null | Key | Default | Extra |
+-------+-------------+------+-----+-------------------+-----------------------------+
| id | int(11) | YES | | NULL | |
| txt | varchar(20) | YES | | NULL | |
| time | timestamp | NO | | CURRENT_TIMESTAMP | on update CURRENT_TIMESTAMP |
| time2 | datetime | YES | | NULL | |
+-------+-------------+------+-----+-------------------+-----------------------------+
4 rows in set (0.00 sec)
mysql> select * from test;
+------+------+---------------------+---------------------+
| id | txt | time | time2 |
+------+------+---------------------+---------------------+
| 1 | test | 2015-07-09 10:14:47 | 2015-07-09 10:14:47 |
| 2 | test | 2015-07-09 10:14:50 | 2015-07-09 10:14:50 |
| 3 | test | 2015-07-09 10:14:53 | 2015-07-09 10:14:53 |
| 4 | test | 2015-07-09 10:14:56 | 2015-07-09 10:14:56 |
| 5 | test | 2015-07-09 10:14:59 | 2015-07-09 10:14:59 |
+------+------+---------------------+---------------------+
5 rows in set (0.00 sec)
[root@localhost ~]# mysqldump --compact --database test1 >test1.sql
Warning:
Using unique option prefix database instead of databases is deprecated
and will be removed in a future release. Please use the full name
instead.
[root@localhost ~]# more test1.sql
CREATE DATABASE /*!32312 IF NOT EXISTS*/ `test1` /*!40100 DEFAULT CHARACTER SET utf8 */;
USE `test1`;
/*!40101 SET @saved_cs_client = @@character_set_client */;
/*!40101 SET character_set_client = utf8 */;
CREATE TABLE `test` (
`id` int(11) DEFAULT NULL,
`txt` varchar(20) DEFAULT NULL,
`time` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
`time2` datetime DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8;
/*!40101 SET character_set_client = @saved_cs_client */;
INSERT INTO `test` VALUES (1,'test','2015-07-09 02:14:47','2015-07-09 10:14:47'),(2,'test','2015-07-09 02:14:50','2015-07-09 10:14:50'),(3,'test','2015-07-09 02:14:53',
'2015-07-09
10:14:53'),(4,'test','2015-07-09 02:14:56','2015-07-09
10:14:56'),(5,'test','2015-07-09 02:14:59','2015-07-09
10:14:59');
可以看到,mysqldump出来的数据,在脚本里面只要是timestamp类型的时间,都是采用的0时区.
这就是因为在dump之初,mysql就已经做了设置,现在来讲讲,刚开始提到的3行参数:
/*!40103 SET @OLD_TIME_ZONE=@@TIME_ZONE */;
/*!40103 SET TIME_ZONE='+00:00' */;
.......(中间建表啊,插入sql啊忽略)
/*!40103 SET TIME_ZONE=@OLD_TIME_ZONE */;
第一行: /*!40103 SET @OLD_TIME_ZONE=@@TIME_ZONE */; 是表示将现在mysql的时区重新命名,相当于备份当前使用的时区(就这么理解吧,小学语文是体育老师教的).重命名的目的是,在后面还需要用到,后面再讲;
第二行: /*!40103 SET TIME_ZONE='+00:00' */; 设置当前会话的时区为0时区,不多做解释,这就是为什么在dump出来的时候,timestamp时间会少了8个小时的原因.
前面两行都是在dump文件最开始的时候就定义的...这一抬头就能看到的...
第三行,/*!40103 SET TIME_ZONE=@OLD_TIME_ZONE */; 是在文件的尾端,基本上就是在最后一张表的unlock table table_name;后面.
这一行参数的目的就是将当前会话修改成原来的时区....
这么解释下来..就清楚明了了...
我在线上做的时候,加了compact,导致timestamp类型的时间被改成了0时区了..导致数据混乱...
血的教训啊....哎....
有位大牛跟我说了句:官方给的默认信息,是有一定道理才给的,在自己不是非常清楚的情况下,不要随便修改官方给的默认信息....
很有道理啊....继续干巴爹!
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