如何解析mysqldump备份原理

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这里通过开启general log追踪mysqldump的备份过程，可以动态调整general log的参数设置。一、不加--single-transaction备份

mysqldump --default-character-set=utf8mb4 -uroot --triggers -R -E -A --master-data=2 |gzip >dbbackup.sql.gz

1、连接数据库

2、调整sql_mode、time_zone

3、刷新tables(关闭所有打开的表并清空缓存数据)

4、FLUSH TABLES WITH READ LOCK(执行全局读锁)

5、记录相关变量、参数、binlog位置等

6、备份数据文件、表空间等

7、备份业务表结构、表数据、触发器

8、备份系统表结构、表数据、触发器

9、备份函数、存储过程

10、备份结束退出，全局锁自动释放

2017-06-24T00:48:48.622170Z        56 Connect   root@localhost on  using Socket

2017-06-24T00:48:48.622372Z        56 Query     /*!40100 SET @@SQL_MODE= */

2017-06-24T00:48:48.622500Z        56 Query     /*!40103 SET TIME_ZONE=+00:00 */

2017-06-24T00:48:48.622654Z        56 Query     FLUSH /*!40101 LOCAL */ TABLES

2017-06-24T00:48:48.623539Z        56 Query     FLUSH TABLES WITH READ LOCK

2017-06-24T00:48:48.623669Z        56 Query     SELECT COUNT(*) FROM INFORMATION_SCHEMA.TABLES WHERE table_schema =

performance_schema AND table_name = session_variables

2017-06-24T00:48:48.624191Z        56 Query     SELECT COUNT(*) FROM performance_schema.session_variables WHERE VARI

ABLE_NAME LIKE rocksdb\_skip\_fill\_cache

2017-06-24T00:48:48.625417Z        56 Query     SHOW VARIABLES LIKE gtid\_mode

2017-06-24T00:48:48.627542Z        56 Query     SHOW MASTER STATUS

2017-06-24T00:48:48.627743Z        56 Query     SELECT LOGFILE_GROUP_NAME, FILE_NAME, TOTAL_EXTENTS, INITIAL_SIZE, E

NGINE, EXTRA FROM INFORMATION_SCHEMA.FILES WHERE FILE_TYPE = UNDO LOG AND FILE_NAME IS NOT NULL AND LOGFILE_GROUP_

NAME IS NOT NULL GROUP BY LOGFILE_GROUP_NAME, FILE_NAME, ENGINE, TOTAL_EXTENTS, INITIAL_SIZE ORDER BY LOGFILE_GROUP_

NAME

2017-06-24T00:48:48.628321Z        56 Query     SELECT DISTINCT TABLESPACE_NAME, FILE_NAME, LOGFILE_GROUP_NAME, EXTE

NT_SIZE, INITIAL_SIZE, ENGINE FROM INFORMATION_SCHEMA.FILES WHERE FILE_TYPE = DATAFILE ORDER BY TABLESPACE_NAME, L

OGFILE_GROUP_NAME

2017-06-24T00:48:48.628778Z        56 Query     SHOW DATABASES

2017-06-24T00:48:48.629166Z        56 Query     SHOW VARIABLES LIKE ndbinfo\_version

2017-06-24T00:48:48.631175Z        56 Init DB   dbtest

2017-06-24T00:48:48.631282Z        56 Query     SHOW CREATE DATABASE IF NOT EXISTS `dbtest`

2017-06-24T00:48:48.631415Z        56 Query     show tables

2017-06-24T00:48:48.631704Z        56 Query     show table status like t

2017-06-24T00:48:48.632269Z        56 Query     SET SQL_QUOTE_SHOW_CREATE=1

2017-06-24T00:48:48.632372Z        56 Query     SET SESSION character_set_results = binary

2017-06-24T00:48:48.632462Z        56 Query     show create table `t`

2017-06-24T00:48:48.632642Z        56 Query     SET SESSION character_set_results = utf8mb4

2017-06-24T00:48:48.632810Z        56 Query     show fields from `t`

2017-06-24T00:48:48.633252Z        56 Query     show fields from `t`

2017-06-24T00:48:48.633664Z        56 Query     SELECT /*!40001 SQL_NO_CACHE */ * FROM `t`

2017-06-24T00:48:48.633894Z        56 Query     SET SESSION character_set_results = binary

2017-06-24T00:48:48.634000Z        56 Query     use `dbtest`

2017-06-24T00:48:48.634136Z        56 Query     select @@collation_database

2017-06-24T00:48:48.634281Z        56 Query     SHOW TRIGGERS LIKE t

2017-06-24T00:48:48.634750Z        56 Query     SET SESSION character_set_results = utf8mb4

2017-06-24T00:48:48.634887Z        56 Query     show table status like t1

2017-06-24T00:48:48.635388Z        56 Query     SET SQL_QUOTE_SHOW_CREATE=1

2017-06-24T00:48:48.635483Z        56 Query     SET SESSION character_set_results = binary

2017-06-24T00:48:48.635575Z        56 Query     show create table `t1`

2017-06-24T00:48:48.635719Z        56 Query     SET SESSION character_set_results = utf8mb4

2017-06-24T00:48:48.635852Z        56 Query     show fields from `t1`

2017-06-24T00:48:48.636268Z        56 Query     show fields from `t1`

2017-06-24T00:48:48.636699Z        56 Query     SELECT /*!40001 SQL_NO_CACHE */ * FROM `t1`

2017-06-24T00:48:48.636911Z        56 Query     SET SESSION character_set_results = binary

2017-06-24T00:48:48.637030Z        56 Query     use `dbtest`

2017-06-24T00:48:48.637132Z        56 Query     select @@collation_database

2017-06-24T00:48:48.637264Z        56 Query     SHOW TRIGGERS LIKE t1

2017-06-24T00:48:48.637719Z        56 Query     SET SESSION character_set_results = utf8mb4

2017-06-24T00:48:48.637856Z        56 Query     show table status like t2

2017-06-24T00:48:48.638347Z        56 Query     SET SQL_QUOTE_SHOW_CREATE=1

2017-06-24T00:48:48.638441Z        56 Query     SET SESSION character_set_results = binary

二、加--single-transaction备份

mysqldump --default-character-set=utf8mb4 -uroot --triggers -R -E -A --master-data=2 --single-transaction |gzip >dbbackup.sql.gz

1、连接数据库

2、调整sql_mode,time_zone

3、调整事务隔离界别为RR（SET SESSION TRANSACTION ISOLATION LEVEL REPEATABLE READ）

4、开启事务一致性快照（START TRANSACTION /*!40100 WITH CONSISTENT SNAPSHOT */）

5、记录gtid_mode、binlog位置等信息

6、释放全局锁

7、备份数据文件、表空间数据

8、备份业务数据库表结构

9、设置savepoint sp(SAVEPOINT sp)

10、备份数据表结构、表数据、触发器、事件(每备份完一个表，做一次rollback to savepoint sp，释放DDL锁)

11、备份系统数据库、表结构、触发器

12、备份存储过程、函数

13、释放savepoint

14、备份事件

15、备份结束会话退出

2017-06-24T00:58:05.650060Z        58 Connect   root@localhost on  using Socket

2017-06-24T00:58:05.650336Z        58 Query     /*!40100 SET @@SQL_MODE= */

2017-06-24T00:58:05.650491Z        58 Query     /*!40103 SET TIME_ZONE=+00:00 */

2017-06-24T00:58:05.650703Z        58 Query     SHOW STATUS LIKE binlog_snapshot_%

2017-06-24T00:58:05.660129Z        58 Query     SELECT COUNT(*) FROM INFORMATION_SCHEMA.TABLES WHERE table_schema =

performance_schema AND table_name = session_variables

2017-06-24T00:58:05.660477Z        58 Query     SELECT COUNT(*) FROM performance_schema.session_variables WHERE VARI

ABLE_NAME LIKE rocksdb\_skip\_fill\_cache

2017-06-24T00:58:05.662214Z        58 Query     SET SESSION TRANSACTION ISOLATION LEVEL REPEATABLE READ

2017-06-24T00:58:05.662314Z        58 Query     START TRANSACTION /*!40100 WITH CONSISTENT SNAPSHOT */

2017-06-24T00:58:05.663369Z        58 Query     SHOW VARIABLES LIKE gtid\_mode

2017-06-24T00:58:05.667436Z        58 Query     SHOW STATUS LIKE binlog_snapshot_%

2017-06-24T00:58:05.670160Z        58 Query     UNLOCK TABLES

2017-06-24T00:58:05.670343Z        58 Query     SELECT LOGFILE_GROUP_NAME, FILE_NAME, TOTAL_EXTENTS, INITIAL_SIZE, E

NGINE, EXTRA FROM INFORMATION_SCHEMA.FILES WHERE FILE_TYPE = UNDO LOG AND FILE_NAME IS NOT NULL AND LOGFILE_GROUP_

NAME IS NOT NULL GROUP BY LOGFILE_GROUP_NAME, FILE_NAME, ENGINE, TOTAL_EXTENTS, INITIAL_SIZE ORDER BY LOGFILE_GROUP_

NAME

2017-06-24T00:58:05.671210Z        58 Query     SELECT DISTINCT TABLESPACE_NAME, FILE_NAME, LOGFILE_GROUP_NAME, EXTE

NT_SIZE, INITIAL_SIZE, ENGINE FROM INFORMATION_SCHEMA.FILES WHERE FILE_TYPE = DATAFILE ORDER BY TABLESPACE_NAME, L

OGFILE_GROUP_NAME

2017-06-24T00:58:05.671971Z        58 Query     SHOW DATABASES

2017-06-24T00:58:05.672341Z        58 Query     SHOW VARIABLES LIKE ndbinfo\_version

2017-06-24T00:58:05.675964Z        58 Init DB   dbtest

2017-06-24T00:58:05.676080Z        58 Query     SHOW CREATE DATABASE IF NOT EXISTS `dbtest`

2017-06-24T00:58:05.676223Z        58 Query     SAVEPOINT sp

2017-06-24T00:58:05.676343Z        58 Query     show tables

2017-06-24T00:58:05.676641Z        58 Query     show table status like t

2017-06-24T00:58:05.677297Z        58 Query     SET SQL_QUOTE_SHOW_CREATE=1

2017-06-24T00:58:05.677404Z        58 Query     SET SESSION character_set_results = binary

2017-06-24T00:58:05.677525Z        58 Query     show create table `t`

2017-06-24T00:58:05.677659Z        58 Query     SET SESSION character_set_results = utf8mb4

2017-06-24T00:58:05.677821Z        58 Query     show fields from `t`

2017-06-24T00:58:05.678319Z        58 Query     show fields from `t`

2017-06-24T00:58:05.678746Z        58 Query     SELECT /*!40001 SQL_NO_CACHE */ * FROM `t`

2017-06-24T00:58:05.678967Z        58 Query     SET SESSION character_set_results = binary

2017-06-24T00:58:05.679059Z        58 Query     use `dbtest`

2017-06-24T00:58:05.679211Z        58 Query     select @@collation_database

2017-06-24T00:58:05.679357Z        58 Query     SHOW TRIGGERS LIKE t

2017-06-24T00:58:05.679851Z        58 Query     SET SESSION character_set_results = utf8mb4

2017-06-24T00:58:05.679958Z        58 Query     ROLLBACK TO SAVEPOINT sp

2017-06-24T00:58:05.680059Z        58 Query     show table status like t1

2017-06-24T00:58:05.680589Z        58 Query     SET SQL_QUOTE_SHOW_CREATE=1

2017-06-24T00:58:05.680702Z        58 Query     SET SESSION character_set_results = binary

2017-06-24T00:58:05.680807Z        58 Query     show create table `t1`

2017-06-24T00:58:05.680945Z        58 Query     SET SESSION character_set_results = utf8mb4

2017-06-24T00:58:05.681071Z        58 Query     show fields from `t1`

2017-06-24T00:58:05.681579Z        58 Query     show fields from `t1`

2017-06-24T00:58:05.682021Z        58 Query     SELECT /*!40001 SQL_NO_CACHE */ * FROM `t1`

2017-06-24T00:58:05.682244Z        58 Query     SET SESSION character_set_results = binary

2017-06-24T00:58:05.682369Z        58 Query     use `dbtest`

2017-06-24T00:58:05.682477Z        58 Query     select @@collation_database

2017-06-24T00:58:05.682609Z        58 Query     SHOW TRIGGERS LIKE t1

2017-06-24T00:58:05.683147Z        58 Query     SET SESSION character_set_results = utf8mb4

2017-06-24T00:58:05.683268Z        58 Query     ROLLBACK TO SAVEPOINT sp

2017-06-24T00:58:05.683366Z        58 Query     show table status like t2

2017-06-24T00:58:05.683899Z        58 Query     SET SQL_QUOTE_SHOW_CREATE=1

2017-06-24T00:58:05.684005Z        58 Query     SET SESSION character_set_results = binary

三、数据库恢复

gunzip

2017-06-24T01:06:22.926385Z        64 Connect   root@localhost on dbtest using Socket

2017-06-24T01:06:22.926645Z        64 Query     select @@version_comment limit 1

2017-06-24T01:06:22.927001Z        64 Query     /*!40101 SET @OLD_CHARACTER_SET_CLIENT=@@CHARACTER_SET_CLIENT */

2017-06-24T01:06:22.927161Z        64 Query     /*!40101 SET @OLD_CHARACTER_SET_RESULTS=@@CHARACTER_SET_RESULTS */

2017-06-24T01:06:22.927286Z        64 Query     /*!40101 SET @OLD_COLLATION_CONNECTION=@@COLLATION_CONNECTION */

2017-06-24T01:06:22.927426Z        64 Query     /*!40101 SET NAMES utf8mb4 */

2017-06-24T01:06:22.927580Z        64 Query     /*!40103 SET @OLD_TIME_ZONE=@@TIME_ZONE */

2017-06-24T01:06:22.927735Z        64 Query     /*!40103 SET TIME_ZONE=+00:00 */

2017-06-24T01:06:22.927856Z        64 Query     /*!40014 SET @OLD_UNIQUE_CHECKS=@@UNIQUE_CHECKS, UNIQUE_CHECKS=0 */

2017-06-24T01:06:22.927986Z        64 Query     /*!40014 SET @OLD_FOREIGN_KEY_CHECKS=@@FOREIGN_KEY_CHECKS, FOREIGN_K

EY_CHECKS=0 */

2017-06-24T01:06:22.928099Z        64 Query     /*!40101 SET @OLD_SQL_MODE=@@SQL_MODE, SQL_MODE=NO_AUTO_VALUE_ON_ZE

RO */

2017-06-24T01:06:22.928234Z        64 Query     /*!40111 SET @OLD_SQL_NOTES=@@SQL_NOTES, SQL_NOTES=0 */

2017-06-24T01:06:22.928337Z        64 Query     /*!50717 SET @rocksdb_bulk_load_var_name=rocksdb_bulk_load */

2017-06-24T01:06:22.928527Z        64 Query     /*!50717 SELECT COUNT(*) INTO @rocksdb_has_p_s_session_variables FRO

M INFORMATION_SCHEMA.TABLES WHERE TABLE_SCHEMA = performance_schema AND TABLE_NAME = session_variables */

2017-06-24T01:06:22.928995Z        64 Query     /*!50717 SET @rocksdb_get_is_supported = IF (@rocksdb_has_p_s_sessio

n_variables, SELECT COUNT(*) INTO @rocksdb_is_supported FROM performance_schema.session_variables WHERE VARIABLE_NA

ME=?, SELECT 0) */

2017-06-24T01:06:22.929105Z        64 Query     /*!50717 PREPARE s FROM @rocksdb_get_is_supported */

2017-06-24T01:06:22.929259Z        64 Prepare   SELECT COUNT(*) INTO @rocksdb_is_supported FROM performance_schema.s

ession_variables WHERE VARIABLE_NAME=?

2017-06-24T01:06:22.929346Z        64 Query     /*!50717 EXECUTE s USING @rocksdb_bulk_load_var_name */

2017-06-24T01:06:22.929370Z        64 Execute   SELECT COUNT(*) INTO @rocksdb_is_supported FROM performance_schema.s

ession_variables WHERE VARIABLE_NAME=rocksdb_bulk_load

2017-06-24T01:06:22.931165Z        64 Query     /*!50717 DEALLOCATE PREPARE s */

2017-06-24T01:06:22.931306Z        64 Query     /*!50717 SET @rocksdb_enable_bulk_load = IF (@rocksdb_is_supported,

SET SESSION rocksdb_bulk_load = 1, SET @rocksdb_dummy_bulk_load = 0) */

2017-06-24T01:06:22.931426Z        64 Query     /*!50717 PREPARE s FROM @rocksdb_enable_bulk_load */

2017-06-24T01:06:22.931463Z        64 Prepare   SET @rocksdb_dummy_bulk_load = 0

2017-06-24T01:06:22.931558Z        64 Query     /*!50717 EXECUTE s */

2017-06-24T01:06:22.931573Z        64 Execute   SET @rocksdb_dummy_bulk_load = 0

2017-06-24T01:06:22.931666Z        64 Query     /*!50717 DEALLOCATE PREPARE s */

2017-06-24T01:06:22.931805Z        64 Query     CREATE DATABASE /*!32312 IF NOT EXISTS*/ `dbtest` /*!40100 DEFAULT C

HARACTER SET utf8 */

2017-06-24T01:06:22.932975Z        64 Init DB   dbtest

2017-06-24T01:06:22.933111Z        64 Query     DROP TABLE IF EXISTS `t`

2017-06-24T01:06:22.933728Z        64 Query     /*!40101 SET @saved_cs_client     = @@character_set_client */

2017-06-24T01:06:22.933859Z        64 Query     /*!40101 SET character_set_client = utf8 */

2017-06-24T01:06:22.934023Z        64 Query     CREATE TABLE `t` (

`id` int(11) DEFAULT NULL

) ENGINE=InnoDB DEFAULT CHARSET=utf8

2017-06-24T01:06:22.939020Z        64 Query     /*!40101 SET character_set_client = @saved_cs_client */

2017-06-24T01:06:22.939213Z        64 Query     LOCK TABLES `t` WRITE

2017-06-24T01:06:22.939616Z        64 Query     /*!40000 ALTER TABLE `t` DISABLE KEYS */

2017-06-24T01:06:22.940164Z        64 Query     INSERT INTO `t` VALUES (1)

2017-06-24T01:06:22.941111Z        64 Query     /*!40000 ALTER TABLE `t` ENABLE KEYS */

2017-06-24T01:06:22.941871Z        64 Query     UNLOCK TABLES

2017-06-24T01:06:22.942023Z        64 Query     DROP TABLE IF EXISTS `t1`

2017-06-24T01:06:22.942558Z        64 Query     /*!40101 SET @saved_cs_client     = @@character_set_client */

2017-06-24T01:06:22.942702Z        64 Query     /*!40101 SET character_set_client = utf8 */

2017-06-24T01:06:22.942879Z        64 Query     CREATE TABLE `t1` (

`id` int(11) DEFAULT NULL,

  `name` varchar(30) DEFAULT NULL

) ENGINE=InnoDB DEFAULT CHARSET=utf8

2017-06-24T01:06:22.946848Z        64 Query     /*!40101 SET character_set_client = @saved_cs_client */

2017-06-24T01:06:22.946986Z        64 Query     LOCK TABLES `t1` WRITE

2017-06-24T01:06:22.947344Z        64 Query     /*!40000 ALTER TABLE `t1` DISABLE KEYS */

2017-06-24T01:06:22.947867Z        64 Query     INSERT INTO `t1` VALUES (1,name)

2017-06-24T01:06:22.948877Z        64 Query     /*!40000 ALTER TABLE `t1` ENABLE KEYS */

2017-06-24T01:06:22.949727Z        64 Query     UNLOCK TABLES

2017-06-24T01:06:22.949847Z        64 Query     DROP TABLE IF EXISTS `t2`

2017-06-24T01:06:22.950384Z        64 Query     /*!40101 SET @saved_cs_client     = @@character_set_client */

2017-06-24T01:06:22.950488Z        64 Query     /*!40101 SET character_set_client = utf8 */

2017-06-24T01:06:22.950632Z        64 Query     CREATE TABLE `t2` (

`id` int(11) DEFAULT NULL,

  `name` varchar(30) DEFAULT NULL

) ENGINE=InnoDB DEFAULT CHARSET=utf8

2017-06-24T01:06:22.954865Z        64 Query     /*!40101 SET character_set_client = @saved_cs_client */

2017-06-24T01:06:22.955009Z        64 Query     LOCK TABLES `t2` WRITE

2017-06-24T01:06:22.955370Z        64 Query     /*!40000 ALTER TABLE `t2` DISABLE KEYS */

2017-06-24T01:06:22.955873Z        64 Query     INSERT INTO `t2` VALUES (1,name),(1,name)

2017-06-24T01:06:22.957048Z        64 Query     /*!40000 ALTER TABLE `t2` ENABLE KEYS */

2017-06-24T01:06:22.957872Z        64 Query     UNLOCK TABLES

2017-06-24T01:06:22.958010Z        64 Query     DROP TABLE IF EXISTS `t3`

2017-06-24T01:06:22.958512Z        64 Query     /*!40101 SET @saved_cs_client     = @@character_set_client */

2017-06-24T01:06:22.958618Z        64 Query     /*!40101 SET character_set_client = utf8 */

2017-06-24T01:06:22.958778Z        64 Query     CREATE TABLE `t3` (

  `id` int(11) DEFAULT NULL,

  `name` varchar(30) DEFAULT NULL

) ENGINE=InnoDB DEFAULT CHARSET=utf8

2017-06-24T01:06:22.972610Z        64 Query     /*!40101 SET character_set_client = @saved_cs_client */

2017-06-24T01:06:22.972767Z        64 Query     LOCK TABLES `t3` WRITE

2017-06-24T01:06:22.973184Z        64 Query     /*!40000 ALTER TABLE `t3` DISABLE KEYS */

2017-06-24T01:06:23.001988Z        64 Query     INSERT INTO `t3` VALUES (1,name1),(2,name2),(3,name3)

四、mysqldump备份恢复总结

1、mysqldump是通过select * from table_name来获取表的数据进而完成备份。

2、START TRANSACTION /*!40100 WITH CONSISTENT SNAPSHOT */必须放到FLUSH TABLES WITH READ LOCK和UNLOCK TABLES之间，放到之前会造成START TRANSACTION /*!40100 WITH CONSISTENT SNAPSHOT */和FLUSH TABLES WITH READ LOCK之间执行的DML语句丢失，放到之后，会造成从库重复插入数据。

3、mysqldump只适合放到业务低峰期做，如果备份的过程中数据操作很频繁，会造成Undo表空间越来越大，undo表空间默认是放到共享表空间中的，而ibdata的特性是一旦增大，就不会收缩。（可重复读的数据会在undo中保存，dml也会产生相关的redo/undo）

4、--single-transaction开启事务一致性快照，开始savepoint，每次备份完执行rollback to savepoint为了防止表的DDL阻塞，而调整事务隔离界别RR为了保障会话的可重复读，从而达到备份数据的一致性。

以上就是如何解析mysqldump备份原理，小编相信有部分知识点可能是我们日常工作会见到或用到的。希望你能通过这篇文章学到更多知识。更多详情敬请关注行业资讯频道。