作者：翟硕
爱可生 DBA 团队成员，负责公司 DMP 产品的运维和客户 MySQL 问题的处理。擅长数据库故障处理。对数据库技术和 python 有着浓厚的兴趣。
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Online DDL 工具 gh-ost
一、gh-ost 介绍
gh-ost 是 GitHub 发布的一款用于 MySQL 的无触发器在线模式迁移解决方案。它是可测试的，并提供暂停，动态控制/重新配置，审计和许多操作特权。它在整个迁移过程中，对主服务器产生的工作量很少，与已迁移表上的现有工作分离。
gh-ost 与所有现有的在线模式更改工具都以类似的方式操作：它们以与原始表相似的方式创建幽灵表，将数据从原始表缓慢且增量地复制到幽灵表，同时应用正在进行的更改（INSERT，DELETE，UPDATE）到幽灵表。最后，在适当的时候，它用幽灵表替换了原始表。gh-ost 使用相同的模式。但是，它与所有现有工具的不同之处在于不使用触发器。取而代之的是，gh-ost 使用二进制日志流捕获表的更改，然后将其异步应用到幽灵表。
gh-ost 承担一些其他工具留给数据库执行的任务。gh-ost 可以更好地控制迁移过程；可以真正暂停它；可以真正将迁移的写入负载与主服务器的工作负载分离。此外，它还提供了许多可操作的特权，使其更安全、可信赖且易于使用。
二、gh-ost 的三种模式架构
2.1、连接从库，在主库转换
这是 gh-ost 默认的工作模式，它会查看从库情况，找到集群的主库并且连接上去，对主库侵入最少
大体步骤是：
- 在主库上创建 _xxx_gho（和原表表结构一致）、_xxx_ghc（记录变更日志），并修改 _xxx_gho 表结构；
- 从 slave 上读取二进制日志事件，将变更应用到主库上的 _xxx_gho 表；
- 在主库上读源表的数据写入 _xxx_gho 表中；
- 在主库上完成表切换。
2.2、连接主库，在主库转换
需要使用 --allow-on-master 选项：
- 在主库上创建 _xxx_gho、_xxx_ghc，并修改 _xxx_gho 表结构；
- 从主库上读取二进制日志事件，将变更应用到主库上的 _xxx_gho 表；
- 在主库上读源表的数据写入 _xxx_gho 表中；
- 在主库上完成表切换。
2.3、在从库上测试和转换
这种模式会在从库上做修改。gh-ost 仍然会连上主库，但所有操作都是在从库上做的，不会对主库产生任何影响。在操作过程中，gh-ost 也会不时地暂停，以便从库的数据可以保持最新。
--migrate-on-replica 选项让 gh-ost 直接在从库上修改表。最终的切换过程也是在从库正常复制的状态下完成的。
--test-on-replica 表明操作只是为了测试目的。在进行最终的切换操作之前，复制会被停止。原始表和临时表会相互切换，再切换回来，最终相当于原始表没被动过。主从复制暂停的状态下，你可以检查和对比这两张表中的数据。
三、下载安装
3.1、下载
访问github，在此页面 https://github.com/github/gh-... 下载 gh-ost 最新的 rpm 安装包。
或者使用 wget 获取安装包
# 使用 wget 获取安装包
[root@10-186-61-20 ~]# wget https://github.com/github/gh-ost/releases/download/v1.0.49/gh-ost-1.0.49-1.x86_64.rpm
3.2、安装
使用 rpm 命令进行安装
# 使用rpm安装
[root@10-186-61-20 ~]# rpm -ivh gh-ost-1.0.49-1.x86_64.rpm
Preparing... ################################# [100%]
Updating / installing...
1:gh-ost-1:1.0.49-1 ################################# [100%]
# 验证是否安装成功
[root@10-186-61-20 ~]# gh-ost --version
1.0.49
四、使用
4.1、常用参数介绍
| 参数 | 解释 |
|---|---|
allow-on-master |
允许迁移直接在主上运行，最好是在从上运行 |
alter |
所要更改表结构的语句 |
assume-master-host |
明确的告诉gh-ost主机的身份，这在主主复制中是有用的，或者是在tungsten-replicator中，gh-ost无法确定主 |
assume-rbr |
当确定服务器采用了ROW格式的binlog时，可以显式的指定为“true”，避免重启复制，不需要super权限，否则gh-ost无法判断当前启动的复制进程是否使用了row格式进行复制，并且会重启复制以确定使用了row格式，需要用户具有super权限。 |
chunk-size |
每次从原表copy数据的行数 |
concurrent-rowcount |
在行复制开始后，并发的对行进行计数，然后调整行估计。当为false时，先对行计数，然后进行行复制（默认true） |
conf |
配置文件，可以写入用户名和密码：[client]user=ghostpassword=123456 |
critical-load |
设置status-name=threshold，使用逗号隔开，当超过阈值时，程序会退出 |
database |
转换表所在的库名 |
dml-batch-size |
在单个事务中应用DML事件的批处理大小(范围为1-100)(默认为10) |
exact-rowcount |
实际计数表行，而不是估计它们(结果是更准确的进度估计)（select count(*) from ...） |
execute |
实际执行alter并迁移表。默认是noop:执行一些测试并退出 |
master-password |
主服务器的密码，如果与从不同。使用--assume-master-host |
master-user |
主服务器的用户，如果与从不同。使用--assume-master-host |
max-lag-millis |
节流操作的复制延时,复制延迟超过此值时会触发节流（默认1500ms） |
max-load |
当负载超过status-name=threshold阈值时，出发节流，例如max-load='Threads_running=100,Threads_connected=500' |
migrate-on-replica |
让迁移在从上完整的运行，包括转换 |
nice-ratio |
每次复制行休眠的时间，0代表不休眠，1 复制行1ms，休眠1ms，0.7 代表复制10ms，休眠7ms |
ok-to-drop-table |
操作完成后删除旧表 |
panic-flag-file |
创建该文件时，程序立即终止 |
host |
连接的MySQL主机（默认127.0.0.1） |
user |
MySQL用户 |
password |
MySQL密码 |
port |
MySQL端口号 |
postpone-cut-over-flag-file |
当这个文件存在时，迁移将推迟交换表的最后阶段，并将继续同步ghost表。一旦文件被删除，切换/交换就可以开始执行了。 |
replica-server-id |
gh-ost在创建复制线程时使用的server_id |
serve-socket-file |
socket文件位置 |
switch-to-rbr |
自动切换为row格式 |
table |
要进行更改的表 |
test-on-replica |
在从库上测试 |
test-on-replica-skip-replica-stop |
在从库上测试的时候不要停止复制 |
throttle-additional-flag-file |
存在此文件时操作暂停;提示:保持默认值，用于调节多个gh-ost操作(默认值“/tmp/gh-ost.throttle”) |
throttle-control-replicas |
检查延迟的副本列表;逗号分隔的 |
throttle-flag-file |
存在此文件时操作暂停;提示:使用特定于被修改的表的文件 |
timestamp-old-table |
在旧表名中使用时间戳。这使得旧的表名惟一且不冲突的交叉迁移 |
4.2、交互式命令
- 需要安装
nmap-ncat包来使用 nc 命令 - 使用方式为
echo "命令" | nc -U socket文件名，例如：echo status | nc -U sbtest1.gh-ost.socket
4.2.1、status
查看详细的执行状态信息。
[root@10-186-61-96 tmp]# echo status | nc -U sbtest1.gh-ost.socket
# Migrating `sbtest`.`sbtest1`; Ghost table is `sbtest`.`_sbtest1_gho`
# Migrating 10-186-61-20:3306; inspecting 10-186-61-20:3306; executing on 10-186-61-96
# Migration started at Mon Feb 17 02:08:10 +0000 2020
# chunk-size: 100000; max-lag-millis: 1500ms; dml-batch-size: 100; max-load: Threads_running=100; critical-load: Threads_running=1000; nice-ratio: 0.000000
# throttle-flag-file: /tmp/sbtest1.throttle
# throttle-additional-flag-file: /tmp/gh-ost.throttle
# throttle-control-replicas count: 1
# postpone-cut-over-flag-file: /tmp/sbtest1.postpone
# panic-flag-file: /tmp/sbtest1.panic
# Serving on unix socket: /tmp/sbtest1.gh-ost.socket
Copy: 19733607/19731368 100.0%; Applied: 3425325; Backlog: 863/1000; Time: 5h18m48s(total), 5h18m48s(copy); streamer: mysql_bin.000083:192819590; Lag: 0.01s, State: throttled, 10.186.61.96:3306 replica-lag=3.686724s; ETA: due
4.2.2、sup
打印简短的状态信息。
[root@10-186-61-96 tmp]# echo sup | nc -U sbtest1.gh-ost.socket
Copy: 19833607/19731368 100.5%; Applied: 3479988; Backlog: 1000/1000; Time: 5h22m21s(total), 5h22m21s(copy); streamer: mysql_bin.000084:12427624; Lag: 1.61s, State: migrating; ETA: due
4.2.3、coordinates
打印当前检查的 binlog 的位置信息。
[root@10-186-61-96 tmp]# echo coordinates |nc -U sbtest1.gh-ost.socket
mysql_bin.000131:10563681
4.2.4、可动态修改的参数
具体参数含义参考常用参数介绍。
chunk-size= # Set a new chunk-size
dml-batch-size= # Set a new dml-batch-size
nice-ratio= # Set a new nice-ratio, immediate sleep after each row-copy operation, float (examples: 0 is aggressive, 0.7 adds 70% runtime, 1.0 doubles runtime, 2.0 triples runtime, ...)
critical-load= # Set a new set of max-load thresholds
max-lag-millis= # Set a new replication lag threshold
replication-lag-query= # Set a new query that determines replication lag (no quotes)
max-load= # Set a new set of max-load thresholds
throttle-query= # Set a new throttle-query (no quotes)
throttle-http= # Set a new throttle URL
throttle-control-replicas= # Set a new comma delimited list of throttle control replicas
使用示例：
[root@10-186-61-96 tmp]# echo "chunk-size=10000" |nc -U sbtest1.gh-ost.socket
4.2.5、强制节流和取消节流
throttle # Force throttling
no-throttle # End forced throttling (other throttling may still apply)
4.2.6、取消推迟转换
gh-ost 默认在完成所有的 copy 动作后，不会马上转换原表和幽灵表，而是继续读取binlog应用到幽灵表中，直到发出转换的动作，所以发出此命令会立刻开始转换。
unpostpone # Bail out a cut-over postpone; proceed to cut-over
4.2.7、立刻停止进程
不清理现场，发出此命令后会立刻停止所有动作并退出进程。
panic # panic and quit without cleanup
4.2.8、help
打印出所有可用命令与解释。
[root@10-186-61-103 tmp]# echo help | nc -U sbtest1.gh-ost.socket
available commands:
status # Print a detailed status message
sup # Print a short status message
coordinates # Print the currently inspected coordinates
chunk-size= # Set a new chunk-size
dml-batch-size= # Set a new dml-batch-size
nice-ratio= # Set a new nice-ratio, immediate sleep after each row-copy operation, float (examples: 0 is aggressive, 0.7 adds 70% runtime, 1.0 doubles runtime, 2.0 triples runtime, ...)
critical-load= # Set a new set of max-load thresholds
max-lag-millis= # Set a new replication lag threshold
replication-lag-query= # Set a new query that determines replication lag (no quotes)
max-load= # Set a new set of max-load thresholds
throttle-query= # Set a new throttle-query (no quotes)
throttle-http= # Set a new throttle URL
throttle-control-replicas= # Set a new comma delimited list of throttle control replicas
throttle # Force throttling
no-throttle # End forced throttling (other throttling may still apply)
unpostpone # Bail out a cut-over postpone; proceed to cut-over
panic # panic and quit without cleanup
help # This message
- use '?' (question mark) as argument to get info rather than set. e.g. "max-load=?" will just print out current max-load.
4.3、使用示例
本示例模拟更改字段数据类型，将 sbtest1 表的 c 字段由 char(120) 改为varchar(200)。采用连接从库，在主库转换的模式架构。
4.3.1、测试环境
- CPU：4C
- 内存：4G
- 操作系统版本：CentOS 7.5.1804
- MySQL版本：5.7.29
MySQL架构：主从复制
- 主库：10.186.61.88:3306
- 从库：10.186.61.101:3306
- gh-ost版本：1.0.49
4.3.2、准备工作
检查从库的 binlog_format 参数和 log_slave_update 参数是或否正确。
mysql> select @@global.binlog_format,@@log_slave_updates;
+------------------------+---------------------+
| @@global.binlog_format | @@log_slave_updates |
+------------------------+---------------------+
| ROW | 1 |
+------------------------+---------------------+
1 row in set (0.00 sec)
确定需要变更的表没有被复制过滤。
mysql> show slave status\G
*************************** 1. row ***************************
-- 省略其他信息
Replicate_Do_DB:
Replicate_Ignore_DB:
Replicate_Do_Table:
Replicate_Ignore_Table:
Replicate_Wild_Do_Table:
Replicate_Wild_Ignore_Table:
-- 省略其他信息
确认需要变更的表存在主键或者非空的唯一键。
mysql> desc sbtest1;
+-------+-----------+------+-----+---------+----------------+
| Field | Type | Null | Key | Default | Extra |
+-------+-----------+------+-----+---------+----------------+
| id | int(11) | NO | PRI | NULL | auto_increment |
| k | int(11) | NO | MUL | 0 | |
| c | char(120) | NO | | | |
| pad | char(60) | NO | | | |
+-------+-----------+------+-----+---------+----------------+
4 rows in set (0.00 sec)
创建 ghost 使用的变更用户。
mysql> GRANT ALTER, CREATE, DELETE, DROP, INDEX, INSERT, LOCK TABLES, SELECT, TRIGGER, UPDATE,SUPER, REPLICATION SLAVE on *.* TO ghost@'%' identified by 'ghost';
Query OK, 0 rows affected, 1 warning (0.01 sec)
将用户和密码写入工作目录的配置文件中。
[root@10-186-61-88 ~]# cat ghost.conf
[client]
user=ghost
password=ghost
4.3.3、开始执行更改操作
开启一个 screen，防止变更中途连接断开。
[root@10-186-61-88 ~]# screen
将变更的 alter 语句写成以下形式。
modify c varchar(200) not null default ""
执行命令开始变更，变更之前先去掉 --execute 选项模拟执行过程，查看执行中是否有问题。
[root@10-186-61-88 ~]# gh-ost --conf=ghost.conf --database=sbtest --table=sbtest1 \
--alter='modify c varchar(200) not null default ""' --max-load=Threads_running=100 \
--critical-load=Threads_running=1000 --critical-load-interval-millis=100 \
--chunk-size=100000 --throttle-control-replicas="10.186.61.101:3306" \
--max-lag-millis=1500 --host=10.186.61.101 --port=3306 --verbose \
--default-retries=120 --dml-batch-size=100 \
--assume-rbr --assume-master-host=10.186.61.88 \
--panic-flag-file=/tmp/sbtest1.panic \
--postpone-cut-over-flag-file=/tmp/sbtest1.postpone \
--throttle-flag-file=/tmp/sbtest1.throttle \
--timestamp-old-table \
--serve-socket-file=/tmp/sbtest1.gh-ost.socket
2020-07-24 15:06:28 INFO starting gh-ost 1.0.49
2020-07-24 15:06:28 INFO Migrating `sbtest`.`sbtest1`
2020-07-24 15:06:28 INFO connection validated on 10.186.61.101:3306
2020-07-24 15:06:28 INFO User has SUPER, REPLICATION SLAVE privileges, and has ALL privileges on `sbtest`.*
2020-07-24 15:06:28 INFO binary logs validated on 10.186.61.101:3306
2020-07-24 15:06:28 INFO Inspector initiated on 10-186-61-101:3306, version 5.7.29-log
2020-07-24 15:06:28 INFO Table found. Engine=InnoDB
2020-07-24 15:06:28 INFO Estimated number of rows via EXPLAIN: 4814427
2020-07-24 15:06:28 INFO Master forced to be 10.186.61.88:3306
2020-07-24 15:06:28 INFO log_slave_updates validated on 10.186.61.101:3306
2020-07-24 15:06:28 INFO connection validated on 10.186.61.101:3306
2020-07-24 15:06:28 INFO Connecting binlog streamer at mysql_bin.000008:95041262
[2020/07/24 15:06:28] [info] binlogsyncer.go:133 create BinlogSyncer with config {99999 mysql 10.186.61.101 3306 ghost false false false UTC true 0 0s 0s 0 false}
[2020/07/24 15:06:28] [info] binlogsyncer.go:354 begin to sync binlog from position (mysql_bin.000008, 95041262)
[2020/07/24 15:06:28] [info] binlogsyncer.go:203 register slave for master server 10.186.61.101:3306
[2020/07/24 15:06:28] [info] binlogsyncer.go:723 rotate to (mysql_bin.000008, 95041262)
2020-07-24 15:06:28 INFO rotate to next log from mysql_bin.000008:0 to mysql_bin.000008
2020-07-24 15:06:28 INFO connection validated on 10.186.61.88:3306
2020-07-24 15:06:28 INFO connection validated on 10.186.61.88:3306
2020-07-24 15:06:28 INFO will use time_zone='SYSTEM' on applier
2020-07-24 15:06:28 INFO Examining table structure on applier
2020-07-24 15:06:28 INFO Applier initiated on 10-186-61-88:3306, version 5.7.29-log
2020-07-24 15:06:28 INFO Dropping table `sbtest`.`_sbtest1_ghc`
2020-07-24 15:06:28 INFO Table dropped
2020-07-24 15:06:28 INFO Creating changelog table `sbtest`.`_sbtest1_ghc`
2020-07-24 15:06:28 INFO Changelog table created
2020-07-24 15:06:28 INFO Creating ghost table `sbtest`.`_sbtest1_gho`
2020-07-24 15:06:28 INFO Ghost table created
2020-07-24 15:06:28 INFO Altering ghost table `sbtest`.`_sbtest1_gho`
2020-07-24 15:06:28 INFO Ghost table altered
2020-07-24 15:06:28 INFO Created postpone-cut-over-flag-file: /tmp/sbtest1.postpone
2020-07-24 15:06:28 INFO Waiting for ghost table to be migrated. Current lag is 0s
2020-07-24 15:06:28 INFO Intercepted changelog state GhostTableMigrated
2020-07-24 15:06:28 INFO Handled changelog state GhostTableMigrated
2020-07-24 15:06:28 INFO Chosen shared unique key is PRIMARY
2020-07-24 15:06:28 INFO Shared columns are id,k,c,pad
2020-07-24 15:06:28 INFO Listening on unix socket file: /tmp/sbtest1.gh-ost.socket
2020-07-24 15:06:28 INFO Migration min values: [1]
2020-07-24 15:06:28 INFO Migration max values: [5000000]
2020-07-24 15:06:28 INFO Waiting for first throttle metrics to be collected
2020-07-24 15:06:28 INFO First throttle metrics collected
# Migrating `sbtest`.`sbtest1`; Ghost table is `sbtest`.`_sbtest1_gho`
# Migrating 10-186-61-88:3306; inspecting 10-186-61-101:3306; executing on 10-186-61-88
# Migration started at Fri Jul 24 15:06:28 +0800 2020
# chunk-size: 100000; max-lag-millis: 1500ms; dml-batch-size: 100; max-load: Threads_running=100; critical-load: Threads_running=1000; nice-ratio: 0.000000
# throttle-flag-file: /tmp/sbtest1.throttle
# throttle-additional-flag-file: /tmp/gh-ost.throttle
# throttle-control-replicas count: 1
# postpone-cut-over-flag-file: /tmp/sbtest1.postpone [set]
# panic-flag-file: /tmp/sbtest1.panic
# Serving on unix socket: /tmp/sbtest1.gh-ost.socket
2020-07-24 15:06:28 INFO Row copy complete
# Migrating `sbtest`.`sbtest1`; Ghost table is `sbtest`.`_sbtest1_gho`
# Migrating 10-186-61-88:3306; inspecting 10-186-61-101:3306; executing on 10-186-61-88
# Migration started at Fri Jul 24 15:06:28 +0800 2020
# chunk-size: 100000; max-lag-millis: 1500ms; dml-batch-size: 100; max-load: Threads_running=100; critical-load: Threads_running=1000; nice-ratio: 0.000000
# throttle-flag-file: /tmp/sbtest1.throttle
# throttle-additional-flag-file: /tmp/gh-ost.throttle
# throttle-control-replicas count: 1
# postpone-cut-over-flag-file: /tmp/sbtest1.postpone [set]
# panic-flag-file: /tmp/sbtest1.panic
# Serving on unix socket: /tmp/sbtest1.gh-ost.socket
Copy: 0/4814427 0.0%; Applied: 0; Backlog: 0/1000; Time: 0s(total), 0s(copy); streamer: mysql_bin.000008:95044050; Lag: 0.03s, State: migrating; ETA: N/A
Copy: 0/0 100.0%; Applied: 0; Backlog: 0/1000; Time: 0s(total), 0s(copy); streamer: mysql_bin.000008:95044050; Lag: 0.03s, State: migrating; ETA: due
2020-07-24 15:06:28 INFO New table structure follows
CREATE TABLE `_sbtest1_gho` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`k` int(11) NOT NULL DEFAULT '0',
`c` varchar(200) NOT NULL DEFAULT '',
`pad` char(60) NOT NULL DEFAULT '',
PRIMARY KEY (`id`),
KEY `k_1` (`k`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4
[2020/07/24 15:06:28] [info] binlogsyncer.go:164 syncer is closing...
2020-07-24 15:06:28 INFO Closed streamer connection. err=
2020-07-24 15:06:28 INFO Dropping table `sbtest`.`_sbtest1_ghc`
[2020/07/24 15:06:28] [error] binlogstreamer.go:77 close sync with err: sync is been closing...
[2020/07/24 15:06:28] [info] binlogsyncer.go:179 syncer is closed
2020-07-24 15:06:28 INFO Table dropped
2020-07-24 15:06:28 INFO Dropping table `sbtest`.`_sbtest1_gho`
2020-07-24 15:06:28 INFO Table dropped
2020-07-24 15:06:28 INFO Done migrating `sbtest`.`sbtest1`
2020-07-24 15:06:28 INFO Removing socket file: /tmp/sbtest1.gh-ost.socket
2020-07-24 15:06:28 INFO Tearing down inspector
2020-07-24 15:06:28 INFO Tearing down applier
2020-07-24 15:06:28 INFO Tearing down streamer
2020-07-24 15:06:28 INFO Tearing down throttler
# Done
确认无误后，即可开始正式的更改工作。
gh-ost --conf=ghost.conf --database=sbtest --table=sbtest1 \
--alter='modify c varchar(200) not null default ""' \
--max-load=Threads_running=100 \
--critical-load=Threads_running=1000 \
--critical-load-interval-millis=100 --chunk-size=100000 \
--throttle-control-replicas="10.186.61.101:3306" \
--max-lag-millis=1500 --host=10.186.61.101 \
--port=3306 --verbose --default-retries=120 \
--dml-batch-size=100 --assume-rbr \
--assume-master-host=10.186.61.88 \
--panic-flag-file=/tmp/sbtest1.panic \
--postpone-cut-over-flag-file=/tmp/sbtest1.postpone \
--throttle-flag-file=/tmp/sbtest1.throttle \
--timestamp-old-table \
--serve-socket-file=/tmp/sbtest1.gh-ost.socket --execute
执行过程中会有如下的日志打印,代表的含义如下：
- Copy：从原表 copy row 的进度，三列分别代表已 cpoy 的行、预估行数、进度
- Applied：表示从二进制日志中读取并应用到幽灵表上的行数
- Backlog：当前处理二进制日志的积压数量
- Time：执行时间
- streamer：当前处理到的二进制日志的位置
- Lag：延时时间
- State：状态（migrating：正常迁移，throttled：限流中，postponing cut-over：等待转换）
- ETA：预估的完成耗时
Copy: 300000/4814427 6.2%; Applied: 0; Backlog: 0/1000; Time: 6s(total), 6s(copy); streamer: mysql_bin.000008:116441176; Lag: 1.72s, State: throttled, lag=1.824079s; ETA: 1m30s
Copy: 300000/4814427 6.2%; Applied: 0; Backlog: 0/1000; Time: 7s(total), 7s(copy); streamer: mysql_bin.000008:133260367; Lag: 1.42s, State: migrating; ETA: 1m45s当状态成为 postponing cut-over 后，我们就可以进行下一步的转换环节，转换方式有两种，第一种是删除创建的标志文件，标志文件为 --postpone-cut-over-flag-file 选项定义的。第二种是执行交互式命令，这里我们采用第二种。
通过输出的日志，我们可以看到状态已经处于 postponing cut-over。
Copy: 5000000/5000000 100.0%; Applied: 0; Backlog: 0/1000; Time: 18m0s(total), 1m49s(copy); streamer: mysql_bin.000011:254596764; Lag: 0.02s, State: postponing cut-over; ETA: due
Copy: 5000000/5000000 100.0%; Applied: 0; Backlog: 0/1000; Time: 18m30s(total), 1m49s(copy); streamer: mysql_bin.000011:254786245; Lag: 0.02s, State: postponing cut-over; ETA: due
执行以下命令。
[root@10-186-61-88 tmp]# echo "unpostpone" |nc -U sbtest1.gh-ost.socket
查看日志输出,可以看到转换完成。
Copy: 5000000/5000000 100.0%; Applied: 0; Backlog: 0/1000; Time: 20m27s(total), 1m49s(copy); streamer: mysql_bin.000011:255529733; Lag: 0.02s, State: postponing cut-over; ETA: due
2020-07-24 15:28:53 INFO Grabbing voluntary lock: gh-ost.2088.lock
2020-07-24 15:28:53 INFO Setting LOCK timeout as 6 seconds
2020-07-24 15:28:53 INFO Looking for magic cut-over table
2020-07-24 15:28:53 INFO Creating magic cut-over table `sbtest`.`_sbtest1_20200724150824_del`
2020-07-24 15:28:53 INFO Magic cut-over table created
2020-07-24 15:28:53 INFO Locking `sbtest`.`sbtest1`, `sbtest`.`_sbtest1_20200724150824_del`
2020-07-24 15:28:53 INFO Tables locked
2020-07-24 15:28:53 INFO Session locking original & magic tables is 2088
2020-07-24 15:28:53 INFO Writing changelog state: AllEventsUpToLockProcessed:1595575733351893170
2020-07-24 15:28:53 INFO Waiting for events up to lock
2020-07-24 15:28:53 INFO Intercepted changelog state AllEventsUpToLockProcessed
2020-07-24 15:28:53 INFO Handled changelog state AllEventsUpToLockProcessed
2020-07-24 15:28:54 INFO Waiting for events up to lock: got AllEventsUpToLockProcessed:1595575733351893170
2020-07-24 15:28:54 INFO Done waiting for events up to lock; duration=696.107491ms
# Migrating `sbtest`.`sbtest1`; Ghost table is `sbtest`.`_sbtest1_gho`
# Migrating 10-186-61-88:3306; inspecting 10-186-61-101:3306; executing on 10-186-61-88
# Migration started at Fri Jul 24 15:08:24 +0800 2020
# chunk-size: 100000; max-lag-millis: 1500ms; dml-batch-size: 100; max-load: Threads_running=100; critical-load: Threads_running=1000; nice-ratio: 0.000000
# throttle-flag-file: /tmp/sbtest1.throttle
# throttle-additional-flag-file: /tmp/gh-ost.throttle
# throttle-control-replicas count: 1
# postpone-cut-over-flag-file: /tmp/sbtest1.postpone [set]
# panic-flag-file: /tmp/sbtest1.panic
# Serving on unix socket: /tmp/sbtest1.gh-ost.socket
Copy: 5000000/5000000 100.0%; Applied: 0; Backlog: 0/1000; Time: 20m29s(total), 1m49s(copy); streamer: mysql_bin.000011:255542872; Lag: 0.02s, State: migrating; ETA: due
2020-07-24 15:28:54 INFO Setting RENAME timeout as 3 seconds
2020-07-24 15:28:54 INFO Session renaming tables is 2084
2020-07-24 15:28:54 INFO Issuing and expecting this to block: rename /* gh-ost */ table `sbtest`.`sbtest1` to `sbtest`.`_sbtest1_20200724150824_del`, `sbtest`.`_sbtest1_gho` to `sbtest`.`sbtest1`
2020-07-24 15:28:54 INFO Found atomic RENAME to be blocking, as expected. Double checking the lock is still in place (though I don't strictly have to)
2020-07-24 15:28:54 INFO Checking session lock: gh-ost.2088.lock
2020-07-24 15:28:54 INFO Connection holding lock on original table still exists
2020-07-24 15:28:54 INFO Will now proceed to drop magic table and unlock tables
2020-07-24 15:28:54 INFO Dropping magic cut-over table
2020-07-24 15:28:54 INFO Releasing lock from `sbtest`.`sbtest1`, `sbtest`.`_sbtest1_20200724150824_del`
2020-07-24 15:28:54 INFO Tables unlocked
2020-07-24 15:28:54 INFO Tables renamed
2020-07-24 15:28:54 INFO Lock & rename duration: 721.156968ms. During this time, queries on `sbtest1` were blocked
2020-07-24 15:28:54 INFO Looking for magic cut-over table
[2020/07/24 15:28:54] [info] binlogsyncer.go:164 syncer is closing...
2020-07-24 15:28:54 INFO Closed streamer connection. err=
2020-07-24 15:28:54 INFO Dropping table `sbtest`.`_sbtest1_ghc`
[2020/07/24 15:28:54] [error] binlogstreamer.go:77 close sync with err: sync is been closing...
[2020/07/24 15:28:54] [info] binlogsyncer.go:179 syncer is closed
2020-07-24 15:28:54 INFO Table dropped
2020-07-24 15:28:54 INFO Am not dropping old table because I want this operation to be as live as possible. If you insist I should do it, please add `--ok-to-drop-table` next time. But I prefer you do not. To drop the old table, issue:
2020-07-24 15:28:54 INFO -- drop table `sbtest`.`_sbtest1_20200724150824_del`
2020-07-24 15:28:54 INFO Done migrating `sbtest`.`sbtest1`
2020-07-24 15:28:54 INFO Removing socket file: /tmp/sbtest1.gh-ost.socket
2020-07-24 15:28:54 INFO Tearing down inspector
2020-07-24 15:28:54 INFO Tearing down applier
2020-07-24 15:28:54 INFO Tearing down streamer
2020-07-24 15:28:54 INFO Tearing down throttler
# Done
登陆数据库，查看表结构是否更改。
mysql> desc sbtest1;
+-------+--------------+------+-----+---------+----------------+
| Field | Type | Null | Key | Default | Extra |
+-------+--------------+------+-----+---------+----------------+
| id | int(11) | NO | PRI | NULL | auto_increment |
| k | int(11) | NO | MUL | 0 | |
| c | varchar(200) | NO | | | |
| pad | char(60) | NO | | | |
+-------+--------------+------+-----+---------+----------------+
4 rows in set (0.00 sec)
4.3.4、后续收尾工作
- 验证表数据是否正常
- 删除旧表
mysql> show tables;
+-----------------------------+
| Tables_in_sbtest |
+-----------------------------+
| _sbtest1_20200724150824_del |
| sbtest1 |
+-----------------------------+
2 rows in set (0.00 sec)
mysql> drop table _sbtest1_20200724150824_del;
Query OK, 0 rows affected (0.03 sec)
- 清理残留的标志文件
[root@10-186-61-88 tmp]# rm sbtest1.postpone
rm: remove regular empty file ‘sbtest1.postpone’? y参考：