这篇文章主要介绍“MySQL ONLINE DDL和PT-ONLINE-SCHEMA-CHANGE有哪些区别”，在日常操作中，相信很多人在MySQL ONLINE DDL和PT-ONLINE-SCHEMA-CHANGE有哪些区别问题上存在疑惑，小编查阅了各式资料，整理出简单好用的操作方法，希望对大家解答”MySQL ONLINE DDL和PT-ONLINE-SCHEMA-CHANGE有哪些区别”的疑惑有所帮助！接下来，请跟着小编一起来学习吧！
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mysql5.6之前执行ddl语句会执行表锁，只允许查询不允许更新，执行ddl主要有两种方式copy方式和inplace方式，inplace方式又称为(fast index creation)，其中copy方式全称表锁，inplace方式只支持二级索引添加和删除。5.6之后可以利用Online DDL特性完成在线表结构调整，而pt-tools提供的pt-online-schema-change可以在几乎无表锁的情况下完成在线表结构调整，这里就针对mysql做下ddl的过程研究。
mysql原生的ddl方式实现形式有三种，分别是copy table、inplace、online ddl的方式，其中5.1-5.5版本实现是通过copy table的形式,5.6-5.7增加了inplace方式和Online ddl方式。
一、mysql 原生ddl实现方式
copy方式
(1).新建临时表
(2).锁原表，禁止DML，允许查询
(3).将原表数据拷贝到临时表(无排序，一行一行拷贝)
(4).删除原表，对临时表进行rename，升级字典锁，禁止读写
(5).完成DDL，释放锁
inplace方式
(1).新建索引的数据字典
(2).锁表，禁止DML，允许查询
(3).读取聚集索引，构造新的索引项，排序并插入新索引
(4).等待打开当前表的所有只读事务提交
(5).创建索引结束
online ddl实现
online方式实质也包含了copy和inplace方式，对于不支持online的ddl操作采用copy方式，比如修改列类型，删除主键等；对于inplace方式，mysql内部以“是否修改记录格式”为基准也分为两类，一类需要重建表(修改记录格式)，比如添加、删除列、修改列默认值等；另外一类是只需要修改表的元数据，比如添加、删除索引、修改列名等。Mysql将这两类方式分别称为rebuild方式和no-rebuild方式。online ddl主要包括3个阶段，prepare阶段，ddl执行阶段，commit阶段，rebuild方式比no-rebuild方式实质多了一个ddl执行阶段，prepare阶段和commit阶段类似。下面将主要介绍ddl执行过程中三个阶段的流程。
Prepare阶段：
创建新的临时frm文件
持有EXCLUSIVE-MDL锁，禁止读写
根据alter类型，确定执行方式(copy,online-rebuild,online-norebuild)
更新数据字典的内存对象
分配row_log对象记录增量
生成新的临时ibd文件
ddl执行阶段：
降级EXCLUSIVE-MDL锁，允许读写
扫描old_table的聚集索引每一条记录rec
遍历新表的聚集索引和二级索引，逐一处理
根据rec构造对应的索引项
将构造索引项插入sort_buffer块
将sort_buffer块插入新的索引
处理ddl执行过程中产生的增量(仅rebuild类型需要)
commit阶段
升级到EXCLUSIVE-MDL锁，禁止读写
重做最后row_log中最后一部分增量
更新innodb的数据字典表
提交事务(刷事务的redo日志)
修改统计信息
rename临时idb文件，frm文件
变更完成
| Operation | In-Place? | Copies Table? | Allows Concurrent DML? | Allows Concurrent Query? | Notes |
|---|---|---|---|---|---|
| 添加索引 | Yes* | No* | Yes | Yes | 对全文索引的一些限制 |
| 删除索引 | Yes | No | Yes | Yes | 仅修改表的元数据 |
| OPTIMIZE TABLE | Yes | Yes | Yes | Yes | 从 5.6.17开始使用ALGORITHM=INPLACE，当然如果指定了old_alter_table=1或mysqld启动带--skip-new则将还是COPY模式。如果表上有全文索引只支持COPY |
| 对一列设置默认值 | Yes | No | Yes | Yes | 仅修改表的元数据 |
| 对一列修改auto-increment 的值 | Yes | No | Yes | Yes | 仅修改表的元数据 |
| 添加 foreign key constraint | Yes* | No* | Yes | Yes | 为了避免拷贝表，在约束创建时会禁用foreign_key_checks |
| 删除 foreign key constraint | Yes | No | Yes | Yes | foreign_key_checks 不影响 |
| 改变列名 | Yes* | No* | Yes* | Yes | 为了允许DML并发, 如果保持相同数据类型，仅改变列名 |
| 添加列 | Yes* | Yes* | Yes* | Yes | 尽管允许 ALGORITHM=INPLACE ，但数据大幅重组，所以它仍然是一项昂贵的操作。当添加列是auto-increment，不允许DML并发 |
| 删除列 | Yes | Yes* | Yes | Yes | 尽管允许 ALGORITHM=INPLACE ，但数据大幅重组，所以它仍然是一项昂贵的操作 |
| 修改列数据类型 | No | Yes* | No | Yes | 修改类型或添加长度，都会拷贝表，而且不允许更新操作 |
| 更改列顺序 | Yes | Yes | Yes | Yes | 尽管允许 ALGORITHM=INPLACE ，但数据大幅重组，所以它仍然是一项昂贵的操作 |
|
修改ROW_FORMAT 和KEY_BLOCK_SIZE | Yes | Yes | Yes | Yes | 尽管允许 ALGORITHM=INPLACE ，但数据大幅重组，所以它仍然是一项昂贵的操作 |
|
设置列属性NULL 或NOT NULL | Yes | Yes | Yes | Yes | 尽管允许 ALGORITHM=INPLACE ，但数据大幅重组，所以它仍然是一项昂贵的操作 |
| 添加主键 | Yes* | Yes | Yes | Yes |
尽管允许 ALGORITHM=INPLACE ，但数据大幅重组，所以它仍然是一项昂贵的操作。 如果列定义必须转化NOT NULL，则不允许INPLACE |
| 删除并添加主键 | Yes | Yes | Yes | Yes | 在同一个 ALTER TABLE 语句删除就主键、添加新主键时，才允许inplace；数据大幅重组,所以它仍然是一项昂贵的操作。 |
| 删除主键 | No | Yes | No | Yes | 不允许并发DML，要拷贝表，而且如果没有在同一 ATLER TABLE 语句里同时添加主键则会收到限制 |
| 变更表字符集 | No | Yes | No | Yes | 如果新的字符集编码不同，重建表 |
mysql5.7在线修改表结构案例：
语法
alter table
| ALGORITHM [=] {DEFAULT|INPLACE|COPY}
| ALTER [COLUMN] col_name {SET DEFAULT literal | DROP DEFAULT}
| CHANGE [COLUMN] old_col_name new_col_name column_definition
[FIRST|AFTER col_name]
| LOCK [=] {DEFAULT|NONE|SHARED|EXCLUSIVE}
| MODIFY [COLUMN] col_name column_definition
[FIRST | AFTER col_name]
online ddl的原理是，mysql把在ddl时间内的所有的 插入，更新和删除操作记录到一个日志文件， 然后再把这些增量数据应用到相应的表上(等表上的事务完全释放后)，这个临时日志文件的上限值由innodb_online_alter_log_max_size指定,每次扩展innodb_sort_buffer_size的大小 该参数如果太小有可能导致DDL失败
二、pt-online-schema-change
注意事项：
（1）表存在主键或唯一建
（2）磁盘容量估计
（3）原表不存在触发器
（4）原表进行批量DML操作时，会有一定影响，需特别注意锁等待等参数设置
（5）如果更新的表是被子表外键引用的父表，那么需要相应的更新子表的外键指向
1、onlineddl原理
（1）设置mysql会话参数
SET SESSION innodb_lock_wait_timeout=1
SET SESSION lock_wait_timeout=60
SET SESSION wait_timeout=10000
SET @@SQL_QUOTE_SHOW_CREATE = 1,@@SQL_MODE='NO_AUTO_VALUE_ON_ZERO,NO_ENGINE_SUBSTITUTION'
（2）检查表结构，是否存在主键、其他外键参考、触发器
SHOW TRIGGERS FROM `dbtest` LIKE 't1'
SELECT table_schema, table_name FROM information_schema.key_column_usage WHERE referenced_table_schema='dbtest' AND referenced_table_name='t1'
（3）创建新表
Creating new table...
CREATE TABLE `dbtest`.`_t1_new` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`name` varchar(30) DEFAULT NULL,
PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=1809061 DEFAULT CHARSET=utf8
Created new table dbtest._t1_new OK.
（4）对新表进行DDL操作
Altering new table...
ALTER TABLE `dbtest`.`_t1_new` ADD COLUMN phone varchar(15)
Altered `dbtest`.`_t1_new` OK.
（5）对旧表创建触发器（insert/update/delete）
2017-11-19T18:05:26 Creating triggers...
CREATE TRIGGER `pt_osc_dbtest_t1_del` AFTER DELETE ON `dbtest`.`t1` FOR EACH ROW DELETE IGNORE FROM `dbtest`.`_t1_new` WHERE `dbtest`.`_t1_new`.`id` <=> OLD.`id`
CREATE TRIGGER `pt_osc_dbtest_t1_upd` AFTER UPDATE ON `dbtest`.`t1` FOR EACH ROW REPLACE INTO `dbtest`.`_t1_new` (`id`, `name`) VALUES (NEW.`id`, NEW.`name`)
CREATE TRIGGER `pt_osc_dbtest_t1_ins` AFTER INSERT ON `dbtest`.`t1` FOR EACH ROW REPLACE INTO `dbtest`.`_t1_new` (`id`, `name`) VALUES (NEW.`id`, NEW.`name`)
2017-11-19T18:05:26 Created triggers OK.
（6）copy数据
copy数据一个chunk后会检查thread_running负载、warning、从库信息决定是否继续copy，默认--chunk-time=0.5,根据这个时间copy的记录动态调整chunk-size，在Copy相关的chunk时，会对原表相关记录加S锁。
2017-11-19T18:05:26 Copying approximately 1593410 rows...
INSERT LOW_PRIORITY IGNORE INTO `dbtest`.`_t1_new` (`id`, `name`) SELECT `id`, `name` FROM `dbtest`.`t1` FORCE INDEX(`PRIMARY`) WHERE ((`id` >= ?)) AND ((`id` <= ?)) LOCK IN SHARE MODE /*pt-online-schema-change 9157 copy nibble*/
SELECT /*!40001 SQL_NO_CACHE */ `id` FROM `dbtest`.`t1` FORCE INDEX(`PRIMARY`) WHERE ((`id` >= ?)) ORDER BY `id` LIMIT ?, 2 /*next chunk boundary*/
2017-11-19T18:05:45 Copied rows OK.
（7）分析新表、统计信息
2017-11-19T18:05:45 Analyzing new table..
（8）新、旧表交换，将旧表t1重命名为_t1_old，将新表_t1_new重命名为t1，并删除旧表_t1_old
2017-11-19T18:05:45 Swapping tables...
RENAME TABLE `dbtest`.`t1` TO `dbtest`.`_t1_old`, `dbtest`.`_t1_new` TO `dbtest`.`t1`
2017-11-19T18:05:45 Swapped original and new tables OK.
2017-11-19T18:05:45 Dropping old table...
DROP TABLE IF EXISTS `dbtest`.`_t1_old`
2017-11-19T18:05:45 Dropped old table `dbtest`.`_t1_old` OK.
（9）删除触发器
2017-11-19T18:05:45 Dropping triggers...
DROP TRIGGER IF EXISTS `dbtest`.`pt_osc_dbtest_t1_del`;
DROP TRIGGER IF EXISTS `dbtest`.`pt_osc_dbtest_t1_upd`;
DROP TRIGGER IF EXISTS `dbtest`.`pt_osc_dbtest_t1_ins`;
2017-11-19T18:05:45 Dropped triggers OK.
（10）完成表结构在线修改
Successfully altered `dbtest`.`t1`.
点击(此处)折叠或打开
171119 17:53:00 66 Connect dbuser@BX-128-28 on dbtest
66 Query SHOW VARIABLES LIKE 'innodb\_lock_wait_timeout'
66 Query SET SESSION innodb_lock_wait_timeout=1
66 Query SHOW VARIABLES LIKE 'lock\_wait_timeout'
66 Query SET SESSION lock_wait_timeout=60
66 Query SHOW VARIABLES LIKE 'wait\_timeout'
66 Query SET SESSION wait_timeout=10000
66 Query SELECT @@SQL_MODE
66 Query SET @@SQL_QUOTE_SHOW_CREATE = 1/*!40101, @@SQL_MODE='NO_AUTO_VALUE_ON_ZERO,NO_ENGINE_SUBSTITUTION'*/
66 Query SELECT @@server_id /*!50038 , @@hostname*/
67 Connect dbuser@BX-128-28 on dbtest
67 Query SHOW VARIABLES LIKE 'innodb\_lock_wait_timeout'
67 Query SET SESSION innodb_lock_wait_timeout=1
67 Query SHOW VARIABLES LIKE 'lock\_wait_timeout'
67 Query SET SESSION lock_wait_timeout=60
67 Query SHOW VARIABLES LIKE 'wait\_timeout'
67 Query SET SESSION wait_timeout=10000
67 Query SELECT @@SQL_MODE
67 Query SET @@SQL_QUOTE_SHOW_CREATE = 1/*!40101, @@SQL_MODE='NO_AUTO_VALUE_ON_ZERO,NO_ENGINE_SUBSTITUTION'*/
67 Query SELECT @@server_id /*!50038 , @@hostname*/
66 Query SHOW VARIABLES LIKE 'wsrep_on'
66 Query SHOW VARIABLES LIKE 'version%'
66 Query SHOW ENGINES
66 Query SHOW VARIABLES LIKE 'innodb_version'
66 Query SHOW VARIABLES LIKE 'innodb_stats_persistent'
66 Query SELECT CONCAT(@@hostname, @@port)
66 Query SHOW TABLES FROM `dbtest` LIKE 't1'
66 Query SHOW TRIGGERS FROM `dbtest` LIKE 't1'
66 Query /*!40101 SET @OLD_SQL_MODE := @@SQL_MODE, @@SQL_MODE := '', @OLD_QUOTE := @@SQL_QUOTE_SHOW_CREATE, @@SQL_QUOTE_SHOW_CREATE := 1 */
66 Query USE `dbtest`
66 Query SHOW CREATE TABLE `dbtest`.`t1`
66 Query /*!40101 SET @@SQL_MODE := @OLD_SQL_MODE, @@SQL_QUOTE_SHOW_CREATE := @OLD_QUOTE */
66 Query EXPLAIN SELECT * FROM `dbtest`.`t1` WHERE 1=1
66 Query SELECT table_schema, table_name FROM information_schema.key_column_usage WHERE referenced_table_schema='dbtest' AND referenced_table_name='t1'
66 Query SHOW VARIABLES LIKE 'wsrep_on'
66 Query /*!40101 SET @OLD_SQL_MODE := @@SQL_MODE, @@SQL_MODE := '', @OLD_QUOTE := @@SQL_QUOTE_SHOW_CREATE, @@SQL_QUOTE_SHOW_CREATE := 1 */
66 Query USE `dbtest`
66 Query SHOW CREATE TABLE `dbtest`.`t1`
66 Query /*!40101 SET @@SQL_MODE := @OLD_SQL_MODE, @@SQL_QUOTE_SHOW_CREATE := @OLD_QUOTE */
66 Query CREATE TABLE `dbtest`.`_t1_new` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`name` varchar(30) DEFAULT NULL,
PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=1809061 DEFAULT CHARSET=utf8
66 Query ALTER TABLE `dbtest`.`_t1_new` ADD COLUMN phone varchar(15)
66 Query /*!40101 SET @OLD_SQL_MODE := @@SQL_MODE, @@SQL_MODE := '', @OLD_QUOTE := @@SQL_QUOTE_SHOW_CREATE, @@SQL_QUOTE_SHOW_CREATE := 1 */
66 Query USE `dbtest`
66 Query SHOW CREATE TABLE `dbtest`.`_t1_new`
66 Query /*!40101 SET @@SQL_MODE := @OLD_SQL_MODE, @@SQL_QUOTE_SHOW_CREATE := @OLD_QUOTE */
66 Query EXPLAIN SELECT * FROM `dbtest`.`t1` WHERE 1=1
66 Query SELECT /*!40001 SQL_NO_CACHE */ `id` FROM `dbtest`.`t1` FORCE INDEX(`PRIMARY`) ORDER BY `id` LIMIT 1 /*first lower boundary*/
66 Query SHOW TABLES FROM `dbtest` LIKE '\_t1\_new'
66 Query DROP TABLE IF EXISTS `dbtest`.`_t1_new`
67 Quit
66 Quit
2、增加字段
预执行：pt-online-schema-change --user=dbuser --password=123456 --host=10.xx --alter "ADD COLUMN phone varchar(15)" D=dbtest,t=t1 --print --dry-run
点击(此处)折叠或打开
Operation, tries, wait:
analyze_table, 10, 1
copy_rows, 10, 0.25
create_triggers, 10, 1
drop_triggers, 10, 1
swap_tables, 10, 1
update_foreign_keys, 10, 1
Starting a dry run. `dbtest`.`t1` will not be altered. Specify --execute instead of --dry-run to alter the table.
Creating new table...
CREATE TABLE `dbtest`.`_t1_new` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`name` varchar(30) DEFAULT NULL,
PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=1809061 DEFAULT CHARSET=utf8
Created new table dbtest._t1_new OK.
Altering new table...
ALTER TABLE `dbtest`.`_t1_new` ADD COLUMN phone varchar(15)
Altered `dbtest`.`_t1_new` OK.
Not creating triggers because this is a dry run.
CREATE TRIGGER `pt_osc_dbtest_t1_del` AFTER DELETE ON `dbtest`.`t1` FOR EACH ROW DELETE IGNORE FROM `dbtest`.`_t1_new` WHERE `dbtest`.`_t1_new`.`id` <=> OLD.`id`
CREATE TRIGGER `pt_osc_dbtest_t1_upd` AFTER UPDATE ON `dbtest`.`t1` FOR EACH ROW REPLACE INTO `dbtest`.`_t1_new` (`id`, `name`) VALUES (NEW.`id`, NEW.`name`)
CREATE TRIGGER `pt_osc_dbtest_t1_ins` AFTER INSERT ON `dbtest`.`t1` FOR EACH ROW REPLACE INTO `dbtest`.`_t1_new` (`id`, `name`) VALUES (NEW.`id`, NEW.`name`)
Not copying rows because this is a dry run.
INSERT LOW_PRIORITY IGNORE INTO `dbtest`.`_t1_new` (`id`, `name`) SELECT `id`, `name` FROM `dbtest`.`t1` FORCE INDEX(`PRIMARY`) WHERE ((`id` >= ?)) AND ((`id` <= ?)) LOCK IN SHARE MODE /*pt-online-schema-change 9137 copy nibble*/
SELECT /*!40001 SQL_NO_CACHE */ `id` FROM `dbtest`.`t1` FORCE INDEX(`PRIMARY`) WHERE ((`id` >= ?)) ORDER BY `id` LIMIT ?, 2 /*next chunk boundary*/
Not swapping tables because this is a dry run.
Not dropping old table because this is a dry run.
Not dropping triggers because this is a dry run.
DROP TRIGGER IF EXISTS `dbtest`.`pt_osc_dbtest_t1_del`;
DROP TRIGGER IF EXISTS `dbtest`.`pt_osc_dbtest_t1_upd`;
DROP TRIGGER IF EXISTS `dbtest`.`pt_osc_dbtest_t1_ins`;
2017-11-19T17:53:00 Dropping new table...
DROP TABLE IF EXISTS `dbtest`.`_t1_new`;
2017-11-19T17:53:00 Dropped new table OK.
Dry run complete. `dbtest`.`t1` was not altered.
正式执行：pt-online-schema-change --user=dbuser --password=123456 --host=10.xx --alter "ADD COLUMN phone varchar(15)" D=dbtest,t=t1 --print --execute
点击(此处)折叠或打开
No slaves found. See --recursion-method if host BX-128-28 has slaves.
Not checking slave lag because no slaves were found and --check-slave-lag was not specified.
Operation, tries, wait:
analyze_table, 10, 1
copy_rows, 10, 0.25
create_triggers, 10, 1
drop_triggers, 10, 1
swap_tables, 10, 1
update_foreign_keys, 10, 1
Altering `dbtest`.`t1`...
Creating new table...
CREATE TABLE `dbtest`.`_t1_new` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`name` varchar(30) DEFAULT NULL,
PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=1809061 DEFAULT CHARSET=utf8
Created new table dbtest._t1_new OK.
Altering new table...
ALTER TABLE `dbtest`.`_t1_new` ADD COLUMN phone varchar(15)
Altered `dbtest`.`_t1_new` OK.
2017-11-19T18:05:26 Creating triggers...
CREATE TRIGGER `pt_osc_dbtest_t1_del` AFTER DELETE ON `dbtest`.`t1` FOR EACH ROW DELETE IGNORE FROM `dbtest`.`_t1_new` WHERE `dbtest`.`_t1_new`.`id` <=> OLD.`id`
CREATE TRIGGER `pt_osc_dbtest_t1_upd` AFTER UPDATE ON `dbtest`.`t1` FOR EACH ROW REPLACE INTO `dbtest`.`_t1_new` (`id`, `name`) VALUES (NEW.`id`, NEW.`name`)
CREATE TRIGGER `pt_osc_dbtest_t1_ins` AFTER INSERT ON `dbtest`.`t1` FOR EACH ROW REPLACE INTO `dbtest`.`_t1_new` (`id`, `name`) VALUES (NEW.`id`, NEW.`name`)
2017-11-19T18:05:26 Created triggers OK.
2017-11-19T18:05:26 Copying approximately 1593410 rows...
INSERT LOW_PRIORITY IGNORE INTO `dbtest`.`_t1_new` (`id`, `name`) SELECT `id`, `name` FROM `dbtest`.`t1` FORCE INDEX(`PRIMARY`) WHERE ((`id` >= ?)) AND ((`id` <= ?)) LOCK IN SHARE MODE /*pt-online-schema-change 9157 copy nibble*/
SELECT /*!40001 SQL_NO_CACHE */ `id` FROM `dbtest`.`t1` FORCE INDEX(`PRIMARY`) WHERE ((`id` >= ?)) ORDER BY `id` LIMIT ?, 2 /*next chunk boundary*/
2017-11-19T18:05:45 Copied rows OK.
2017-11-19T18:05:45 Analyzing new table...
2017-11-19T18:05:45 Swapping tables...
RENAME TABLE `dbtest`.`t1` TO `dbtest`.`_t1_old`, `dbtest`.`_t1_new` TO `dbtest`.`t1`
2017-11-19T18:05:45 Swapped original and new tables OK.
2017-11-19T18:05:45 Dropping old table...
DROP TABLE IF EXISTS `dbtest`.`_t1_old`
2017-11-19T18:05:45 Dropped old table `dbtest`.`_t1_old` OK.
2017-11-19T18:05:45 Dropping triggers...
DROP TRIGGER IF EXISTS `dbtest`.`pt_osc_dbtest_t1_del`;
DROP TRIGGER IF EXISTS `dbtest`.`pt_osc_dbtest_t1_upd`;
DROP TRIGGER IF EXISTS `dbtest`.`pt_osc_dbtest_t1_ins`;
2017-11-19T18:05:45 Dropped triggers OK.
Successfully altered `dbtest`.`t1`.
3、删除字段
pt-online-schema-change --user=dbuser --password=123456 --host=10.xx --no-check-replication-filters --recursion-method=none --alter "DROP COLUMN phone " D=dbtest,t=t1 --print --execute
点击(此处)折叠或打开
No slaves found. See --recursion-method if host BX-128-28 has slaves.
Not checking slave lag because no slaves were found and --check-slave-lag was not specified.
Operation, tries, wait:
analyze_table, 10, 1
copy_rows, 10, 0.25
create_triggers, 10, 1
drop_triggers, 10, 1
swap_tables, 10, 1
update_foreign_keys, 10, 1
Altering `dbtest`.`t1`...
Creating new table...
CREATE TABLE `dbtest`.`_t1_new` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`name` varchar(30) DEFAULT NULL,
`phone` varchar(15) DEFAULT NULL,
PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=1809061 DEFAULT CHARSET=utf8
Created new table dbtest._t1_new OK.
Altering new table...
ALTER TABLE `dbtest`.`_t1_new` DROP COLUMN phone
Altered `dbtest`.`_t1_new` OK.
2017-11-19T22:56:33 Creating triggers...
CREATE TRIGGER `pt_osc_dbtest_t1_del` AFTER DELETE ON `dbtest`.`t1` FOR EACH ROW DELETE IGNORE FROM `dbtest`.`_t1_new` WHERE `dbtest`.`_t1_new`.`id` <=> OLD.`id`
CREATE TRIGGER `pt_osc_dbtest_t1_upd` AFTER UPDATE ON `dbtest`.`t1` FOR EACH ROW REPLACE INTO `dbtest`.`_t1_new` (`id`, `name`) VALUES (NEW.`id`, NEW.`name`)
CREATE TRIGGER `pt_osc_dbtest_t1_ins` AFTER INSERT ON `dbtest`.`t1` FOR EACH ROW REPLACE INTO `dbtest`.`_t1_new` (`id`, `name`) VALUES (NEW.`id`, NEW.`name`)
2017-11-19T22:56:33 Created triggers OK.
2017-11-19T22:56:33 Copying approximately 1597892 rows...
INSERT LOW_PRIORITY IGNORE INTO `dbtest`.`_t1_new` (`id`, `name`) SELECT `id`, `name` FROM `dbtest`.`t1` FORCE INDEX(`PRIMARY`) WHERE ((`id` >= ?)) AND ((`id` <= ?)) LOCK IN SHARE MODE /*pt-online-schema-change 9444 copy nibble*/
SELECT /*!40001 SQL_NO_CACHE */ `id` FROM `dbtest`.`t1` FORCE INDEX(`PRIMARY`) WHERE ((`id` >= ?)) ORDER BY `id` LIMIT ?, 2 /*next chunk boundary*/
2017-11-19T22:56:52 Copied rows OK.
2017-11-19T22:56:52 Analyzing new table...
2017-11-19T22:56:52 Swapping tables...
RENAME TABLE `dbtest`.`t1` TO `dbtest`.`_t1_old`, `dbtest`.`_t1_new` TO `dbtest`.`t1`
2017-11-19T22:56:52 Swapped original and new tables OK.
2017-11-19T22:56:52 Dropping old table...
DROP TABLE IF EXISTS `dbtest`.`_t1_old`
2017-11-19T22:56:52 Dropped old table `dbtest`.`_t1_old` OK.
2017-11-19T22:56:52 Dropping triggers...
DROP TRIGGER IF EXISTS `dbtest`.`pt_osc_dbtest_t1_del`;
DROP TRIGGER IF EXISTS `dbtest`.`pt_osc_dbtest_t1_upd`;
DROP TRIGGER IF EXISTS `dbtest`.`pt_osc_dbtest_t1_ins`;
2017-11-19T22:56:52 Dropped triggers OK.
Successfully altered `dbtest`.`t1`.
4、添加索引
pt-online-schema-change --user=dbuser --password=123456 --host=10.xx --no-check-replication-filters --recursion-method=none --alter "add key idx_name(name)" D=dbtest,t=t1 --print --execute
点击(此处)折叠或打开
No slaves found. See --recursion-method if host BX-128-28 has slaves.
Not checking slave lag because no slaves were found and --check-slave-lag was not specified.
Operation, tries, wait:
analyze_table, 10, 1
copy_rows, 10, 0.25
create_triggers, 10, 1
drop_triggers, 10, 1
swap_tables, 10, 1
update_foreign_keys, 10, 1
Altering `dbtest`.`t1`...
Creating new table...
CREATE TABLE `dbtest`.`_t1_new` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`name` varchar(30) DEFAULT NULL,
PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=1809061 DEFAULT CHARSET=utf8
Created new table dbtest._t1_new OK.
Altering new table...
ALTER TABLE `dbtest`.`_t1_new` add key(name)
Altered `dbtest`.`_t1_new` OK.
2017-11-19T23:00:40 Creating triggers...
CREATE TRIGGER `pt_osc_dbtest_t1_del` AFTER DELETE ON `dbtest`.`t1` FOR EACH ROW DELETE IGNORE FROM `dbtest`.`_t1_new` WHERE `dbtest`.`_t1_new`.`id` <=> OLD.`id`
CREATE TRIGGER `pt_osc_dbtest_t1_upd` AFTER UPDATE ON `dbtest`.`t1` FOR EACH ROW REPLACE INTO `dbtest`.`_t1_new` (`id`, `name`) VALUES (NEW.`id`, NEW.`name`)
CREATE TRIGGER `pt_osc_dbtest_t1_ins` AFTER INSERT ON `dbtest`.`t1` FOR EACH ROW REPLACE INTO `dbtest`.`_t1_new` (`id`, `name`) VALUES (NEW.`id`, NEW.`name`)
2017-11-19T23:00:40 Created triggers OK.
2017-11-19T23:00:40 Copying approximately 1559718 rows...
INSERT LOW_PRIORITY IGNORE INTO `dbtest`.`_t1_new` (`id`, `name`) SELECT `id`, `name` FROM `dbtest`.`t1` FORCE INDEX(`PRIMARY`) WHERE ((`id` >= ?)) AND ((`id` <= ?)) LOCK IN SHARE MODE /*pt-online-schema-change 9453 copy nibble*/
SELECT /*!40001 SQL_NO_CACHE */ `id` FROM `dbtest`.`t1` FORCE INDEX(`PRIMARY`) WHERE ((`id` >= ?)) ORDER BY `id` LIMIT ?, 2 /*next chunk boundary*/
2017-11-19T23:01:09 Copied rows OK.
2017-11-19T23:01:09 Analyzing new table...
2017-11-19T23:01:09 Swapping tables...
RENAME TABLE `dbtest`.`t1` TO `dbtest`.`_t1_old`, `dbtest`.`_t1_new` TO `dbtest`.`t1`
2017-11-19T23:01:09 Swapped original and new tables OK.
2017-11-19T23:01:09 Dropping old table...
DROP TABLE IF EXISTS `dbtest`.`_t1_old`
2017-11-19T23:01:09 Dropped old table `dbtest`.`_t1_old` OK.
2017-11-19T23:01:09 Dropping triggers...
DROP TRIGGER IF EXISTS `dbtest`.`pt_osc_dbtest_t1_del`;
DROP TRIGGER IF EXISTS `dbtest`.`pt_osc_dbtest_t1_upd`;
DROP TRIGGER IF EXISTS `dbtest`.`pt_osc_dbtest_t1_ins`;
2017-11-19T23:01:09 Dropped triggers OK.
Successfully altered `dbtest`.`t1`.
5、删除索引
pt-online-schema-change --user=dbuser --password=123456 --host=10.xx --no-check-replication-filters --recursion-method=none --alter "DROP key idx_name" D=dbtest,t=t1 --print --execute
6、改变字段类型、长度
pt-online-schema-change --user=dbuser --password=123456 --host=10.xx --no-check-replication-filters --recursion-method=none --alter "modify name varchar(10)" D=dbtest,t=t1 --print --execute
到此，关于“MySQL ONLINE DDL和PT-ONLINE-SCHEMA-CHANGE有哪些区别”的学习就结束了，希望能够解决大家的疑惑。理论与实践的搭配能更好的帮助大家学习，快去试试吧！若想继续学习更多相关知识，请继续关注创新互联网站，小编会继续努力为大家带来更多实用的文章！
