MySQL CDC

MySQL CDC source connector

Description

The MySQL CDC connector allows for reading snapshot data and incremental data from MySQL database. This document describes how to set up the MySQL CDC connector to run SQL queries against MySQL databases.

Key features

Creating MySQL user

You have to define a MySQL user with appropriate permissions on all databases that the Debezium MySQL connector monitors.

Create the MySQL user:

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

Grant the required permissions to the user:

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

Finalize the user’s permissions:

mysql> FLUSH PRIVILEGES;

Enabling the MySQL Binlog

You must enable binary logging for MySQL replication. The binary logs record transaction updates for replication tools to propagate changes.

Check whether the log-bin option is already on:

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)

If inconsistent with the above results, configure your MySQL server configuration file($MYSQL_HOME/mysql.cnf) with the following properties, which are described in the table below:

# Enable binary replication log and set the prefix, expiration, and log format.
# The prefix is arbitrary, expiration can be short for integration tests but would
# be longer on a production system. Row-level info is required for ingest to work.
# Server ID is required, but this will vary on production systems
server-id         = 223344
log_bin           = mysql-bin
expire_logs_days  = 10
binlog_format     = row
# mysql 5.6+ requires binlog_row_image to be set to FULL
binlog_row_image  = FULL

# enable gtid mode
# mysql 5.6+ requires gtid_mode to be set to ON
gtid_mode = on
enforce_gtid_consistency = on

Restart MySQL Server

/etc/inint.d/mysqld restart

Confirm your changes by checking the binlog status once more:

MySQL 5.5:

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            |
| log_bin                  | ON             |
+--------------------------+----------------+
5 rows in set (0.00 sec)

MySQL 5.6+:

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)

Notes

Setting up MySQL session timeouts

When an initial consistent snapshot is made for large databases, your established connection could timeout while the tables are being read. You can prevent this behavior by configuring interactive_timeout and wait_timeout in your MySQL configuration file.

interactive_timeout: The number of seconds the server waits for activity on an interactive connection before closing it. See MySQL’s documentation for more details.
wait_timeout: The number of seconds the server waits for activity on a non-interactive connection before closing it. See MySQL’s documentation for more details.

For more database settings see Debezium MySQL Connector

Data Type Mapping

Mysql Data Type

Nexus Data Type

BIT(1) TINYINT(1)

BOOLEAN

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 ENUM

STRING

DATE

TIME(s)

DATETIME TIMESTAMP(s)

TIMESTAMP(s)

BINARY VARBINAR BIT(p) TINYBLOB MEDIUMBLOB BLOB LONGBLOB GEOMETRY

BYTES

Source Options

Name

Type

Required

Default

Description

base-url

String

Yes

The URL of the JDBC connection. Refer to a case: jdbc:mysql://localhost:3306:3306/test.

username

String

Yes

Name of the database to use when connecting to the database server.

password

String

Yes

Password to use when connecting to the database server.

database-names

List

Database name of the database to monitor.

table-names

List

Yes

Table name of the database to monitor. The table name needs to include the database name, for example: database_name.table_name

table-names-config

List

Table config list. for example: [{"table": "db1.schema1.table1","primaryKeys":["key1"]}]

startup.mode

Enum

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

Start from the specified binlog file name. Note, This option is required when the startup.mode option used specific.

startup.specific-offset.pos

Long

Start from the specified binlog file position. Note, This option is required when the startup.mode option used specific.

stop.mode

Enum

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

Stop from the specified binlog file name. Note, This option is required when the stop.mode option used specific.

stop.specific-offset.pos

Long

Stop from the specified binlog file position. Note, This option is required when the stop.mode option used specific.

snapshot.split.size

Integer

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

1024

The maximum fetch size for per poll when read table snapshot.

server-id

String

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 6500 and 2,148,492,146, though we recommend setting an explicit value.

server-time-zone

String

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

30000

The maximum time that the connector should wait after trying to connect to the database server before timing out.

connect.max-retries

Integer

The max retry times that the connector should retry to build database server connection.

connection.pool.size

Integer

The jdbc connection pool size.

chunk-key.even-distribution.factor.upper-bound

Double

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

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

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

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

false

Enable exactly once semantic.

format

Enum

DEFAULT

Optional output format for MySQL CDC, valid enumerations are DEFAULT、COMPATIBLE_DEBEZIUM_JSON.

debezium

Config

Pass-through Debezium's properties to Debezium Embedded Engine which is used to capture data changes from MySQL server.

common-options

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 {
    base-url = "jdbc:mysql://localhost:3306/testdb"
    username = "root"
    password = "root@123"
    table-names = ["testdb.table1", "testdb.table2"]
    
    startup.mode = "initial"
  }
}

sink {
  Console {
  }
}

Support debezium-compatible format send to kafka

Must be used with kafka connector sink, see compatible debezium format for details

Support custom primary key for table

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

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

sink {
  Console {
  }
}

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Last updated 9 months ago

Description​

Key features​

Creating MySQL user​

Enabling the MySQL Binlog​

Notes​

Data Type Mapping​

Source Options​

Task Example​

Simple​

Support debezium-compatible format send to kafka​

Support custom primary key for table​

Description

Key features

Creating MySQL user

Enabling the MySQL Binlog

Notes

Data Type Mapping

Source Options

Task Example

Simple

Support debezium-compatible format send to kafka

Support custom primary key for table