全方位解读SeaTunnel MySQL CDC连接器：实现数据高效同步的强大工具

在当今数据快速增长的时代，实时、高效地同步和处理来自各种数据源的信息成为了企业和开发者面临的重要挑战。

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MySQL作为广泛使用的数据库之一，其变更数据捕获（CDC）功能对于实现这一目标至关重要。在这篇文章中，我们将深入探讨MySQL CDC源连接器在SeaTunnel框架下的应用，涵盖从基础设置到高级配置的各个方面。

MySQL CDC源连接器

支持的引擎

SeaTunnel Zeta
Flink

主要特性

批量
流式
精确一次
列投影
并行处理
支持用户定义的拆分

描述

MySQL CDC连接器允许从MySQL数据库读取快照数据和增量数据。本文档描述了如何设置MySQL CDC连接器以对MySQL数据库运行SQL查询。

支持的数据源信息

数据源	支持的版本	驱动	Url	Maven
MySQL	MySQL: 5.6, 5.7, 8.0.x RDS MySQL: 5.6, 5.7, 8.0.x	com.mysql.cj.jdbc.Driver	jdbc:mysql://localhost:3306/test	https://mvnrepository.com/artifact/mysql/mysql-connector-java/8.0.28

数据库依赖

安装Jdbc驱动程序

请将mysql驱动程序下载并放入${SEATUNNEL_HOME}/lib/目录中。例如：cp mysql-connector-java-xxx.jar $SEATNUNNEL_HOME/lib/

创建MySQL用户

您必须为Debezium MySQL连接器监视的所有数据库定义一个具有适当权限的MySQL用户。

创建MySQL用户：

mysql> CREATE USER 'user'@'localhost' IDENTIFIED BY 'password';

为用户授予所需权限：

mysql> GRANT SELECT, RELOAD, SHOW DATABASES, REPLICATION SLAVE, REPLICATION CLIENT ON *.* TO 'user' IDENTIFIED BY 'password';

完成用户的权限设置：

mysql> FLUSH PRIVILEGES;

启用MySQL binlog

为了实现MySQL的复制，必须启用二进制日志。二进制日志记录了用于复制工具传播更改的事务更新。

检查log-bin选项是否已经开启：

mysql> show variables where variable_name in ('log_bin', 'binlog_format', 'binlog_row_image', 'gtid_mode', 'enforce_gtid_consistency');
+--------------------------+----------------+
| Variable_name            | Value          |
+--------------------------+----------------+
| binlog_format            | ROW            |
| binlog_row_image         | FULL           |
| enforce_gtid_consistency | ON             |
| gtid_mode                | ON             |
| log_bin                  | ON             |
+--------------------------+----------------+
5 rows in set (0.00 sec)

如果与上述结果不一致，请使用以下属性配置您的MySQL服务器配置文件（$MYSQL_HOME/mysql.cnf），如下表所示：

# 启用二进制复制日志并设置前缀、过期时间和日志格式。
# 前缀是任意的，过期时间对于集成测试可以短一些，但在生产系统中会更长。
# 行级信息对于摄取工作是必需的。
# 服务器ID在生产系统上是必需的，但会有所不同。
server-id         = 223344
log_bin           = mysql-bin
expire_logs_days  = 10
binlog_format     = row
binlog_row_image  = FULL

# 启用gtid模式
gtid_mode = on
enforce_gtid_consistency = on

重启MySQL服务器

/etc/inint.d/mysqld restart

再次确认您的更改，通过再次检查binlog状态：

mysql> show variables where variable_name in ('log_bin', 'binlog_format', 'binlog_row_image', 'gtid_mode', 'enforce_gtid_consistency');
+--------------------------+----------------+
| Variable_name            | Value          |
+--------------------------+----------------+
| binlog_format            | ROW            |
| binlog_row_image         | FULL           |
| enforce_gtid_consistency | ON             |
| gtid_mode                | ON             |
| log_bin                  | ON             |
+--------------------------+----------------+
5 rows in set (0.00 sec)

注意

设置MySQL会话超时

当为大型数据库创建初始一致快照时，在读取表期间，已建立的连接可能会超时。您可以通过在MySQL配置文件中配置interactive_timeout和wait_timeout来防止这种行为。

interactive_timeout：服务器等待交互连接活动关闭之前的秒数。有关更多详细信息，请参阅MySQL文档。
wait_timeout：服务器等待非交互连接活动关闭之前的秒数。有关更多详细信息，请参阅MySQL文档。

有关更多数据库设置，请参见Debezium MySQL连接器

数据类型映射

Mysql Data type	SeaTunnel Data type
BIT(1) TINYINT(1)	BOOLEAN
TINYINT	TINYINT
TINYINT UNSIGNED SMALLINT	SMALLINT
SMALLINT UNSIGNED MEDIUMINT MEDIUMINT UNSIGNED INT INTEGER YEAR	INT
INT UNSIGNED INTEGER UNSIGNED BIGINT	BIGINT
BIGINT UNSIGNED	DECIMAL(20,0)
DECIMAL(p, s) DECIMAL(p, s) UNSIGNED NUMERIC(p, s) NUMERIC(p, s) UNSIGNED	DECIMAL(p,s)
FLOAT FLOAT UNSIGNED	FLOAT
DOUBLE DOUBLE UNSIGNED REAL REAL UNSIGNED	DOUBLE
CHAR VARCHAR TINYTEXT MEDIUMTEXT TEXT LONGTEXT ENUM JSON	STRING
DATE	DATE
TIME	TIME
DATETIME TIMESTAMP	TIMESTAMP
BINARY VARBINAR BIT(p) TINYBLOB MEDIUMBLOB BLOB LONGBLOB	BYTES

源选项

名称	类型	必需	默认值	描述
base-url	String	是	-	JDBC连接的URL。参考示例：`jdbc:mysql://localhost:3306:3306/test`。
username	String	是	-	连接到数据库服务器时使用的数据库名称。
password	String	是	-	连接到数据库服务器时使用的密码。
database-names	List	否	-	要监视的数据库的名称。
table-names	List	是	-	要监视的数据库的表名。表名需要包含数据库名称，例如：`database_name.table_name`。
startup.mode	Enum	No	INITIAL	Optional startup mode for MySQL CDC consumer, valid enumerations are `initial`, `earliest`, `latest` and `specific`. `initial`: Synchronize historical data at startup, and then synchronize incremental data. `earliest`: Startup from the earliest offset possible. `latest`: Startup from the latest offset. `specific`: Startup from user-supplied specific offsets.
startup.specific-offset.file	String	No	-	Start from the specified binlog file name. Note, This option is required when the `startup.mode` option used `specific`.
startup.specific-offset.pos	Long	No	-	Start from the specified binlog file position. Note, This option is required when the `startup.mode` option used `specific`.
stop.mode	Enum	No	NEVER	Optional stop mode for MySQL CDC consumer, valid enumerations are `never`, `latest` or `specific`. `never`: Real-time job don't stop the source. `latest`: Stop from the latest offset. `specific`: Stop from user-supplied specific offset.
stop.specific-offset.file	String	No	-	Stop from the specified binlog file name. Note, This option is required when the `stop.mode` option used `specific`.
stop.specific-offset.pos	Long	No	-	Stop from the specified binlog file position. Note, This option is required when the `stop.mode` option used `specific`.
snapshot.split.size	Integer	No	8096	The split size (number of rows) of table snapshot, captured tables are split into multiple splits when read the snapshot of table.
snapshot.fetch.size	Integer	No	1024	The maximum fetch size for per poll when read table snapshot.
server-id	String	No	-	A numeric ID or a numeric ID range of this database client, The numeric ID syntax is like `5400`, the numeric ID range syntax is like '5400-5408'. Every ID must be unique across all currently-running database processes in the MySQL cluster. This connector joins the MySQL cluster as another server (with this unique ID) so it can read the binlog. By default, a random number is generated between 5400 and 6400, though we recommend setting an explicit value.
server-time-zone	String	No	UTC	The session time zone in database server. If not set, then ZoneId.systemDefault() is used to determine the server time zone.
connect.timeout.ms	Duration	No	30000	The maximum time that the connector should wait after trying to connect to the database server before timing out.
connect.max-retries	Integer	No	3	The max retry times that the connector should retry to build database server connection.
connection.pool.size	Integer	No	20	The jdbc connection pool size.
chunk-key.even-distribution.factor.upper-bound	Double	No	100	The upper bound of the chunk key distribution factor. This factor is used to determine whether the table data is evenly distributed. If the distribution factor is calculated to be less than or equal to this upper bound (i.e., (MAX(id) - MIN(id) + 1) / row count), the table chunks would be optimized for even distribution. Otherwise, if the distribution factor is greater, the table will be considered as unevenly distributed and the sampling-based sharding strategy will be used if the estimated shard count exceeds the value specified by `sample-sharding.threshold`. The default value is 100.0.
chunk-key.even-distribution.factor.lower-bound	Double	No	0.05	The lower bound of the chunk key distribution factor. This factor is used to determine whether the table data is evenly distributed. If the distribution factor is calculated to be greater than or equal to this lower bound (i.e., (MAX(id) - MIN(id) + 1) / row count), the table chunks would be optimized for even distribution. Otherwise, if the distribution factor is less, the table will be considered as unevenly distributed and the sampling-based sharding strategy will be used if the estimated shard count exceeds the value specified by `sample-sharding.threshold`. The default value is 0.05.
sample-sharding.threshold	Integer	No	1000	This configuration specifies the threshold of estimated shard count to trigger the sample sharding strategy. When the distribution factor is outside the bounds specified by `chunk-key.even-distribution.factor.upper-bound` and `chunk-key.even-distribution.factor.lower-bound`, and the estimated shard count (calculated as approximate row count / chunk size) exceeds this threshold, the sample sharding strategy will be used. This can help to handle large datasets more efficiently. The default value is 1000 shards.
inverse-sampling.rate	Integer	No	1000	The inverse of the sampling rate used in the sample sharding strategy. For example, if this value is set to 1000, it means a 1/1000 sampling rate is applied during the sampling process. This option provides flexibility in controlling the granularity of the sampling, thus affecting the final number of shards. It's especially useful when dealing with very large datasets where a lower sampling rate is preferred. The default value is 1000.
exactly_once	Boolean	No	true	Enable exactly once semantic.
format	Enum	No	DEFAULT	Optional output format for MySQL CDC, valid enumerations are `DEFAULT`、`COMPATIBLE_DEBEZIUM_JSON`.
debezium	Config	No	-	Pass-through Debezium's properties to Debezium Embedded Engine which is used to capture data changes from MySQL server.
common-options		no	-	Source plugin common parameters, please refer to Source Common Options for details

Task Example

Simple

Support multi-table reading

env {
  parallelism = 1
  job.mode = "STREAMING"
  checkpoint.interval = 10000
}

source {
  MySQL-CDC {
    catalog = {
      factory = MySQL
    }
    base-url = "jdbc:mysql://localhost:3306/testdb"
    username = "root"
    password = "root@123"
    table-names = ["testdb.table1", "testdb.table2"]

    startup.mode = "initial"
  }
}

sink {
  Console {
  }
}