mysqldump的一個大失誤.關于--compact參數使用不當的教訓...記錄...備用...
mysqldump 的一個參數 --compact
官網給出的說法是這樣:
--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.
大概意思就是讓導出的腳本里面取消一些注釋和不必要的sql.
下面這這幾行就是加了--compact參數后的抬頭幾行....
-- 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 '資金流水號',
`withdraw_id` varchar(30) DEFAULT NULL COMMENT '提現流水號',
`biz_no` varchar(20) NOT NULL COMMENT '交易流水號',
`withdraw_time` int(11) DEFAULT NULL COMMENT '延遲提現時間（每天定時任務遞減）',
下面在來比較下不加--compact導出后的腳本抬頭幾行:
-- 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 '資金流水號',
`withdraw_id` varchar(30) DEFAULT NULL COMMENT '提現流水號',
`biz_no` varchar(20) NOT NULL COMMENT '交易流水號',
`withdraw_time` int(11) DEFAULT NULL COMMENT '延遲提現時間（每天定時任務遞減）',
兩相比較,就可以看出,加了compact后的腳本的確更緊湊了...少了很多注釋...
最開始我以為是好事,畢竟這些注釋對一相同環境來說,沒什么大的影響..可后來在線上一次操作,導致了大問題產生...
這里,只記錄我這次操作失誤有關的參數...其他的參數,另請參考官網.
/*!40103 SET @OLD_TIME_ZONE=@@TIME_ZONE */;
/*!40103 SET TIME_ZONE='+00:00' */;
.......(中間建表啊,插入sql啊忽略)
/*!40103 SET TIME_ZONE=@OLD_TIME_ZONE */;
我的失誤就是由這三行造成的....在加了compact參數后,是沒有這三行參數的...
失誤是什么勒? 時間...時間相差8小時....都知道了吧....剛好8個時區...我們是北京時間...
先不說原因和問題,,先做一個測試:
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出來的數據,在腳本里面只要是timestamp類型的時間,都是采用的0時區.
這就是因為在dump之初,mysql就已經做了設置,現在來講講,剛開始提到的3行參數:
/*!40103 SET @OLD_TIME_ZONE=@@TIME_ZONE */;
/*!40103 SET TIME_ZONE='+00:00' */;
.......(中間建表啊,插入sql啊忽略)
/*!40103 SET TIME_ZONE=@OLD_TIME_ZONE */;
第一行:
/*!40103 SET @OLD_TIME_ZONE=@@TIME_ZONE */; 是表示將現在mysql的時區重新命名,相當于備份當前使用的時區(就這么理解吧,小學語文是體育老師教的).重命名的目的是,在后面還需要用到,后面再講;
第二行:
/*!40103 SET TIME_ZONE='+00:00' */; 設置當前會話的時區為0時區,不多做解釋,這就是為什么在dump出來的時候,timestamp時間會少了8個小時的原因.
前面兩行都是在dump文件最開始的時候就定義的...這一抬頭就能看到的...
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張表的unlock table table_name;后面.
這一行參數的目的就是將當前會話修改成原來的時區....
這么解釋下來..就清楚明了了...
我在線上做的時候,加了compact,導致timestamp類型的時間被改成了0時區了..導致數據混亂...
血的教訓啊....哎....
有位大牛跟我說了句:官方給的默認信息,是有一定道理才給的,在自己不是非常清楚的情況下,不要隨便修改官方給的默認信息....
很有道理啊....繼續干巴爹!
