作者： EINTR 原文来源：https://tidb.net/blog/d3f87f7e
1. 背景
TiCDC 作为 TiDB 生态系统中的关键组件，在数据复制和同步领域发挥着至关重要的作用。新版 TiCDC 在继承以往版本优势的基础上，进行了全面的优化和升级，进一步提升了性能、稳定性和功能的丰富性。
使用软件版本
过程中使用的软件版本
操作系统:CentOS Linux release 7.9.2009 (Core)
tidb:v8.1.2
mysql:5.7.34
mydumper:0.10.3-1
2. 安装
已经有了 tidb 的集群, 本次将在原来的集群上增加 cdc 组件.
首先添加配置文件
[tidb@test5135 ~]$ cat scale-out.yml cdc_servers: - host: 192.168.5.135 gc-ttl: 86400 data_dir: /tidb-data/cdc-8300 - host: 192.168.5.184 gc-ttl: 86400 data_dir: /tidb-data/cdc-8300 - host: 192.168.5.185 gc-ttl: 86400data_dir: /tidb-data/cdc-8300
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使用 tiup 进行安装.
tiup cluster scale-out tidb-test scale-out.yml
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安装完成后, 出现提示信息
+ Refresh components conifgs - Generate config pd -> 192.168.5.135:2379 ... Done - Generate config pd -> 192.168.5.184:2379 ... Done - Generate config pd -> 192.168.5.185:2379 ... Done - Generate config tikv -> 192.168.5.135:20160 ... Done - Generate config tikv -> 192.168.5.184:20160 ... Done - Generate config tikv -> 192.168.5.185:20160 ... Done - Generate config tidb -> 192.168.5.135:4000 ... Done - Generate config tidb -> 192.168.5.184:4000 ... Done - Generate config tidb -> 192.168.5.185:4000 ... Done - Generate config cdc -> 192.168.5.135:8300 ... Done - Generate config cdc -> 192.168.5.184:8300 ... Done - Generate config cdc -> 192.168.5.185:8300 ... Done - Generate config prometheus -> 192.168.5.135:9090 ... Done - Generate config grafana -> 192.168.5.135:3000 ... Done - Generate config alertmanager -> 192.168.5.135:9093 ... Done+ Reload prometheus and grafana - Reload prometheus -> 192.168.5.135:9090 ... Done - Reload grafana -> 192.168.5.135:3000 ... Done+ [ Serial ] - UpdateTopology: cluster=tidb-testScaled cluster `tidb-test` out successfully
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查看集群的启动信息,cdc 已经正常启动
[tidb@test5135 .tiup]$ tiup cluster display tidb-testCluster type: tidbCluster name: tidb-testCluster version: v8.1.2Deploy user: tidbSSH type: builtinDashboard URL: http://192.168.5.185:2379/dashboardGrafana URL: http://192.168.5.135:3000ID Role Host Ports OS/Arch Status Data Dir Deploy Dir-- ---- ---- ----- ------- ------ -------- ----------192.168.5.135:9093 alertmanager 192.168.5.135 9093/9094 linux/x86_64 Up /tidb-data/alertmanager-9093 /tidb-deploy/alertmanager-9093192.168.5.135:8300 cdc 192.168.5.135 8300 linux/x86_64 Up /tidb-data/cdc-8300 /tidb-deploy/cdc-8300192.168.5.184:8300 cdc 192.168.5.184 8300 linux/x86_64 Up /tidb-data/cdc-8300 /tidb-deploy/cdc-8300192.168.5.185:8300 cdc 192.168.5.185 8300 linux/x86_64 Up /tidb-data/cdc-8300 /tidb-deploy/cdc-8300192.168.5.135:3000 grafana 192.168.5.135 3000 linux/x86_64 Up - /tidb-deploy/grafana-3000192.168.5.135:2379 pd 192.168.5.135 2379/2380 linux/x86_64 Up|L /tidb-data/pd-2379 /tidb-deploy/pd-2379192.168.5.184:2379 pd 192.168.5.184 2379/2380 linux/x86_64 Up /tidb-data/pd-2379 /tidb-deploy/pd-2379192.168.5.185:2379 pd 192.168.5.185 2379/2380 linux/x86_64 Up|UI /tidb-data/pd-2379 /tidb-deploy/pd-2379192.168.5.135:9090 prometheus 192.168.5.135 9090/12020 linux/x86_64 Up /tidb-data/prometheus-8249 /tidb-deploy/prometheus-8249192.168.5.135:4000 tidb 192.168.5.135 4000/10080 linux/x86_64 Up - /tidb-deploy/tidb-4000192.168.5.184:4000 tidb 192.168.5.184 4000/10080 linux/x86_64 Up - /tidb-deploy/tidb-4000192.168.5.185:4000 tidb 192.168.5.185 4000/10080 linux/x86_64 Up - /tidb-deploy/tidb-4000192.168.5.135:20160 tikv 192.168.5.135 20160/20180 linux/x86_64 Up /tidb-data/tikv-20160 /tidb-deploy/tikv-20160192.168.5.184:20160 tikv 192.168.5.184 20160/20180 linux/x86_64 Up /tidb-data/tikv-20160 /tidb-deploy/tikv-20160192.168.5.185:20160 tikv 192.168.5.185 20160/20180 linux/x86_64 Up /tidb-data/tikv-20160 /tidb-deploy/tikv-20160Total nodes: 15
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安装完成后,cdc 命令不能直接使用, 需要加载到环境变量中.
cdc 的命令入口是 cdc, 保存在 $deploy_dir/cdc-8300/bin 下面.
将命令加入到环境变量 export PATH=/home/tidb/.tiup/bin:/tidb-deploy/cdc-8300/bin:$PATH
重新加载环境变量 source .bash_profile, 已经可以正常使用.
[tidb@test5135 scripts]$ cdc versionRelease Version: v8.1.2Git Commit Hash: cd5e9e4ecdd7772a960b78cdbd2f1ebad7fd5cabGit Branch: HEADUTC Build Time: 2024-12-19 12:13:09Go Version: go version go1.21.13 linux/amd64Failpoint Build: false
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3. 启动全量迁移
3.1 关闭 gc
因为在 Dumpling 退出后，GC 可能会被触发，从而导致增量变更迁移失败。
--执行如下命令关闭 GC：mysql> SET GLOBAL tidb_gc_enable=FALSE;Query OK, 0 rows affected (0.05 sec)
--查询 tidb_gc_enable 的取值，判断 GC 是否已关闭：mysql> SELECT @@global.tidb_gc_enable;+-------------------------+| @@global.tidb_gc_enable |+-------------------------+| 0 |+-------------------------+1 row in set (0.01 sec)
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3.2 tidb 导出全量数据
使用 dumpling 从 tidb 导出全量数据,
[tidb@test5135 scripts]$tiup dumpling -u root -P 4000 -h 127.0.0.1 -p"EUi25N@8K1-7c+3^db" --filetype sql -t 8 -o ./dumpling_output -r 200000 -F256MiB
--以下为命令输出A new version of dumpling is available: -> v8.1.2
To update this component: tiup update dumpling To update all components: tiup update --all
The component `dumpling` version is not installed; downloading from repository.Starting component dumpling: /home/tidb/.tiup/components/dumpling/v8.1.2/dumpling -u root -P 4000 -h 127.0.0.1 -p****** --filetype sql -t 8 -o ./dumpling_output -r 200000 -F256MiBRelease version: v8.1.2Git commit hash: 80db67052c0b1d89ab5ea94d6efa576a2191432dGit branch: HEADBuild timestamp: 2024-12-24 06:39:16ZGo version: go version go1.21.13 linux/amd64...[2025/02/26 15:08:30.394 +08:00] [INFO] [main.go:82] ["dump data successfully, dumpling will exit now"]
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3.3 记录导出文件的 TSO
在导出目录的 metadata 文件中记录导出的时间点信息, 方便后面启动 cdc 增量迁移时使用.
[tidb@test5135 ~]$ cat dumpling_output/metadata Started dump at: 2025-02-26 15:08:08SHOW MASTER STATUS: Log: tidb-binlog Pos: 456275706010927125 GTID:
Finished dump at: 2025-02-26 15:08:30
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4. mysql 恢复全量数据
使用 myloader 将 tidb 导出的数据导入到 mysql 中,myloader 使用 0.10 版本及以下版本, 高版本读取元数据报错.
Release v0.10.3 · mydumper/mydumper · GitHub
启动 mysql 任务
[mysql@test5184 tidbback]$ myloader -u root -p "Cx1842#09Gjw0121" -S /data/mysql/data/mysql.sock -d /data/tidbback/dumpling_output/
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5. 使用 cdc 部署增量任务
在上游集群中，执行以下命令创建从上游到下游 mysql 的同步链路：
cdc cli changefeed create \--server=http://192.168.5.135:8300 \--sink-uri="mysql://sync_data:As01FTsxqzHF0upeSkhmUMT@192.168.5.184:3306/" \--changefeed-id="simple-replication-task" \--start-ts="456275706010927125"
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--server:cdc 的服务端
--sink-uri: 下游 mysql 的地址
--changefeed-id: 同步任务的 ID, 如果不写, 将自动生成
--start-ts:dumpling 导出的时间戳
启动 cdc 任务, 任务启动后, 自动转入后台运行.
[tidb@test5135 dumpling_output]$ cdc cli changefeed create --server=http://192.168.5.135:8300 --sink-uri="mysql://sync_data:As01FTsxqzHF0upeSkhmUMT@192.168.5.184:3306/" --changefeed-id="simple-replication-task" --start-ts="456275706010927125"Create changefeed successfully!ID: simple-replication-task
[tidb@test5135 dumpling_output]$ ps -ef|grep cdctidb 1037 11576 0 15:48 pts/2 00:00:00 grep --color=auto cdctidb 6549 1 5 14:05 ? 00:05:23 bin/cdc server --addr 0.0.0.0:8300 --advertise-addr 192.168.5.135:8300 --pd http://192.168.5.135:2379,http://192.168.5.184:2379,http://192.168.5.185:2379 --data-dir=/tidb-data/cdc-8300 --gc-ttl 86400 --config conf/cdc.toml --log-file /tidb-deploy/cdc-8300/log/cdc.log
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6. 测试
在 tidb 中创建一张表, 并向表中添加数据, 在 mysql 中查看数据.
--tidbmysql> CREATE TABLE t1 ( -> id INT AUTO_INCREMENT PRIMARY KEY, -> name VARCHAR(255), -> created TIMESTAMP DEFAULT CURRENT_TIMESTAMP -> );Query OK, 0 rows affected (0.17 sec)
mysql> mysql> mysql> insert into t1(name)values("aa");Query OK, 1 row affected (0.01 sec)
mysql> select * from t1;+----+------+---------------------+| id | name | created |+----+------+---------------------+| 1 | aa | 2025-02-26 16:20:00 |+----+------+---------------------+1 row in set (0.01 sec)
--mysqlmysql> desc t1;+---------+--------------+------+-----+-------------------+----------------+| Field | Type | Null | Key | Default | Extra |+---------+--------------+------+-----+-------------------+----------------+| id | int(11) | NO | PRI | NULL | auto_increment || name | varchar(255) | YES | | NULL | || created | timestamp | NO | | CURRENT_TIMESTAMP | |+---------+--------------+------+-----+-------------------+----------------+3 rows in set (0.00 sec)
mysql> mysql> select * from t1;+----+------+---------------------+| id | name | created |+----+------+---------------------+| 1 | aa | 2025-02-26 16:20:00 |+----+------+---------------------+1 row in set (0.00 sec)
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在借助 TiCDC 成功构建起上下游数据同步链路之后, 原集群中写入的数据能够以极低的延迟快速同步至下游的 mysql 数据库. 这一高效且稳定的同步效果, 为后续的业务调整奠定了坚实基础. 此时, 我们便可以有条不紊地将读流量逐步迁移至新集群, 充分发挥新集群的性能优势, 进一步优化整体业务架构.
7. 问题
问题 1
cdc 启动时报错
[tidb@test5135 scripts]$ cdc cli changefeed create \> --server=http://192.168.5.135:8300 \> --sink-uri="mysql://sync_data:As01FTsxqzHF0upeSkhmUMT@192.168.5.184:3306/" \> --changefeed-id="simple-replication-task"Error: [CDC:ErrMySQLConnectionError]fail to open MySQL connection: Error 1298 (HY000): Unknown or incorrect time zone: 'Asia/Shanghai'
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官方解决方案:https://docs.pingcap.com/zh/tidb/stable/troubleshoot-ticdc#%E5%A6%82%E4%BD%95%E5%A4%84%E7%90%86-ticdc-%E5%88%9B%E5%BB%BA%E5%90%8C%E6%AD%A5%E4%BB%BB%E5%8A%A1%E6%88%96%E5%90%8C%E6%AD%A5%E5%88%B0-mysql-%E6%97%B6%E9%81%87%E5%88%B0-error-1298-unknown-or-incorrect-time-zone-utc-%E9%94%99%E8%AF%AF
在 mysql 中导入时区后正常
[mysql@test5184 scripts]$ mysql_tzinfo_to_sql /usr/share/zoneinfo | mysql -u root mysql -pEnter password: Warning: Unable to load '/usr/share/zoneinfo/iso3166.tab' as time zone. Skipping it.Warning: Unable to load '/usr/share/zoneinfo/leapseconds' as time zone. Skipping it.Warning: Unable to load '/usr/share/zoneinfo/tzdata.zi' as time zone. Skipping it.Warning: Unable to load '/usr/share/zoneinfo/zone.tab' as time zone. Skipping it.Warning: Unable to load '/usr/share/zoneinfo/zone1970.tab' as time zone. Skipping it.
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