MySQL Synchronization to Alibaba Cloud PolarDB-X

NineData data replication supports full data synchronization and incremental data synchronization between self-built MySQL and self-built MySQL data sources.

Feature Introduction

NineData data replication supports high-performance replication of structure, full data, and incremental data between data sources. For certain data sources, it also provides bidirectional replication, enabling the quick construction of geo-distributed active-active business architectures.

Structure: Supports the replication of object structures between homogeneous and heterogeneous data sources, greatly reducing the barrier to data replication between two sources.
Full Data: Achieves row-level concurrent batch replication through intelligent data sharding, effectively ensuring replication performance. The independently developed novel breakpoint resume technology ensures the accuracy of data in tables without primary keys.
Incremental Data: Supports DML and DDL incremental data replication for all object types. By leveraging technologies such as row-level concurrency and hotspot merging, it delivers robust replication performance.
Bidirectional Real-time Data Replication (only between MySQL instances): Direct bidirectional replication of data between multiple nodes ensures that all node data remains up-to-date.

With the above features, it is easy and efficient to achieve scenarios such as full|incremental data replication, full|incremental data migration, full|incremental data synchronization, data integration, and seamless migration without downtime, providing enterprises with flexible and reliable data replication solutions.

Prerequisites

The source and target data sources have been added to NineData. For instructions on how to add them, see Add Data Source.
The source data source is MySQL, with a version of 5.1 or above.
The target data source is Alibaba Cloud PolarDB-X.
The source data source must have Binlog enabled, and the Binlog-related parameters are set as follows:
- binlog_format=ROW
- binlog_row_image=FULL
tip
If the source data source is a replica, to ensure complete Binlog logs are obtained, the log_slave_updates parameter also needs to be enabled.

Usage Limitations

The data replication function is only for the user databases in the data source, and the system databases will not be replicated. For example: information_schema, mysql, performance_schema, sys databases in MySQL type data sources will not be replicated.
The account for source data must have SELECT (for replicate database structure and full data), SHOW VIEW (for replicate views), and REPLICATION CLIENT, REPLICATION SLAVE (for replicate incremental data) privileges on the objects to be replicated. The account for target must have DML and DDL privileges.
Before performing data synchronization, user need to evaluate the performance of the source data source and the target data source, and it is recommended to perform data synchronization during off-peak time. Otherwise, the full data initialization will occupy a certain amount of read and write resources of the source data source and the target data source, increasing database load.
During the synchronization process, if the source data contains views, functions, stored procedures, triggers, and events, after synchronizing to the target data source, the definer of the above objects information will be modified in the target data source to the account that accesses the target data source in the current synchronization task.
It is necessary to ensure that each table in the synchronization object has a primary key or unique constraint, and the column name is unique, otherwise the same data may be synchronized repeatedly.
During the synchronization process, if there are triggers in the source, the system will not synchronize the triggers until the incremental synchronization ends.

Operation Steps

Commercialization Notice

NineData’s data replication product has been commercialized. You can still use 10 replication tasks for free, with the following considerations:

Among the 10 replication tasks, you can include 1 task, with a specification of Micro.
Tasks with a status of do not count towards the 10-task limit. If you have already created 10 replication tasks and want to create more, you can terminate previous replication tasks and then create new ones.
When creating replication tasks, you can only select the you have purchased. Specifications that have not been purchased will be grayed out and cannot be selected. If you need to purchase additional specifications, please contact us through the customer service icon at the bottom right of the page.

Log in to the NineData Console.
Click on in the left navigation bar.
On the page, click on in the top right corner.

On the tab, configure according to the table below and click on .

Parameter	Description
	Enter the name of the data synchronization task. To facilitate subsequent search and management, please use meaningful names as much as possible. Up to 64 characters are supported.
	The data source where the synchronization object is located.
	The data source that receives the synchronization object.
	Choose the content that needs to be copied to the target data source. : Syncs all objects and data from the source data source, i.e., full data replication. The switch on the right is for toggling periodic full replication. For more information, please refer to Periodic Full Replication. : After full sync, perform incremental sync based on the log of the source data source. The icon represents incremental operation type configuration (not supported by some replication links). You can deselect certain operation types as needed. Once deselected, these operations will be ignored during incremental synchronization.
	: Stop the task when the target object already exists during the pre-inspection stage. : Ignore and append write when the target object already exists during the pre-inspection stage. : Delete and rewrite when the target object already exists during the pre-inspection stage.

On the tab, configure the following parameters, then click on .

Parameter	Description
	Choose the content that needs to be copied. You can select to copy all content from the source database, or you can select , select the content that needs to be copied in the list, and click > to add to the right list.

If you need to create multiple replication chains with the same replication object, you can create a configuration file and import it when creating a new task. Click on in the top right corner, then click Download Template to download the configuration file template to your local machine, edit it, and then click to upload the configuration file to achieve batch import. Configuration file description:

Parameter	Description
`source_table_name`	The source table name where the object to be synchronized is located.
`destination_table_name`	The target table name that receives the synchronized object.
`source_schema_name`	The source Schema name where the object to be synchronized is located.
`destination_schema_name`	The target Schema name that receives the synchronized object.
`source_database_name`	The source database name where the object to be synchronized is located.
`target_database_name`	The target database name that receives the synchronized object.
`column_list`	The list of fields that need to be synchronized.
`extra_configuration`	Additional configuration information can be set here: `column_rules`: Used to define column mapping and value rules. Field descriptions: `column_name`: Original column name. `destination_column_name`: Target column name. `column_value`: Value to assign, which can be an SQL function or a constant. `filter_condition`: Used to specify row-level filtering conditions; only rows that meet the criteria will be copied.

tip

An example of the extra_configuration content is as follows:

{
  "extra_config": {
    "column_rules": [
      {
        "column_name": "created_time", // Original column name to map.
        "destination_column_name": "migrated_time", // Target column name mapped to "migrated_time".
        "column_value": "current_timestamp()" // Change the column value to the current timestamp.
      }
    ],
    "filter_condition": "id != 0" // Only rows where ID is not 0 will be synchronized.
  }
}

For a complete example of the configuration file, refer to the downloaded template.

On the tab, the system defaults to selecting the database with the same name in the target data source. If it does not exist, you need to manually select the target database. The table name and column name in the target database need to be consistent with the synchronization object. If they are not consistent, you can also manually map the table name and column name, and then click on . If there are updates in the source and target data sources during the configuration mapping stage, you can click on the button in the top right corner of the page to refresh the information from the source and target data sources.
您还可以进行如下操作：
- 单击页面右侧的，自定义列名同步到目标数据源之后的名称。
- 在页面，单击，通过比较表达式配置过滤条件，仅符合过滤条件的数据会同步到目标数据源。例如，将过滤条件设置为 emp_no>=10005，则 emp_no 列中小于 10005 的数据均不会同步到目标数据源。
- 单击右侧的图标，可搜索表名，并替换成目标名称。
- 在右上角的文本框中输入表名以快速定位到目标表。
- 单击右上角的，可以批量定义通用规则（如表名、字段名大小写转换、前后缀添加、替换等），实现对大量表和字段的统一映射配置。
On the tab, wait for the system to complete the pre-inspection, and after the pre-inspection is passed, click on .
tip
- You can check . After the synchronization task is completed, automatically start data consistency comparison based on the source data source to ensure data consistency on both sides. It starts when the incremental data is first consistent with the source data source and is 0 seconds. You can click on to view the synchronization delay on the page.
- If the pre-inspection does not pass, you need to click on in the column on the right side of the target inspection item, troubleshoot the cause of the failure, manually fix it, and then click on to re-execute the pre-inspection until it passes.
- If the is for the inspection item, it can be fixed or ignored according to the specific situation.
On the page, it prompts , and the synchronization task starts running. At this time, you can perform the following operations:
- Click on to view the execution of each stage of the synchronization task.
- Click on to return to the task list page.

View Synchronization Results

Log in to the NineData Console.
Click on > in the left navigation bar.

On the page, click the of the target synchronization task, and the page description is as follows.

result_sybase

No.	Function	Description
1	Synchronization Delay	The data synchronization delay between the source and target data sources. 0 seconds indicate no delay between the two ends. At this point, you can choose to switch the business to the target data source to achieve a smooth migration.
2	Configure Alerts	After configuring alerts, the system will notify you through your chosen method when the task fails. For more information, please refer to Introduction to Operations Monitoring.
3	More	: Pause the task, only available for tasks in the running status. : Create a new replication task with the same configuration as the current task. : End tasks that are not completed or in listening mode (i.e., incremental synchronization). After terminating the task, it cannot be restarted, please proceed with caution. If the synchronization object includes triggers, trigger replication options will pop up, please choose as needed. : Delete the task, the task cannot be recovered after deletion, please proceed with caution.
4	Full Replication (displayed in scenarios including full replication)	Display the progress and detailed information of full replication. Click on on the right side of the page: View various monitoring metrics during the full replication process. During the full replication process, you can also click on on the right side of the monitoring metrics page to limit the rate of writing to the target data source per second. The unit is rows/second. Click on on the right side of the page: View the execution logs of full replication. Click on the on the right side of the page: View the latest information.
5	Incremental Replication (displayed in scenarios including incremental replication)	Display various monitoring metrics for incremental replication. Click on on the right side of the page: View the operations currently being executed by the replication task, including: : The replication task is executed by multiple threads, displaying the current thread number. : Details of the SQL statement currently being executed by the current thread. : The response time of the current thread, if this value increases, it indicates that the current thread may be stuck due to some reason. : The timestamp when the current thread started. : The status of the current thread. Click on on the right side of the page: Limit the rate of writing to the target data source per second. The unit is rows/second. Click on on the right side of the page: View the execution logs of incremental replication. Click on the on the right side of the page: View the latest information.
6	Modify Objects	Display the modification records of synchronization objects. Click on on the right side of the page to configure synchronization objects. Click on the on the right side of the page: View the latest information.
7	Data Comparison	Display the results of the comparison between the source and target data sources. If you have not enabled data comparison, please click on in the page. Click on on the right side of the page: Re-initiate a comparison between the current source and target data. Click on on the right side of the page: After the comparison task starts, you can click this button to immediately stop the comparison task. Click on on the right side of the page: View the execution logs of consistency comparison. Click on on the right side of the page (only displayed during data comparison): View the trend chart of comparison RPS (records compared per second). Click on to view records from earlier times. Click on in the column on the right side of the comparison list (only displayed under the tab when inconsistencies are found): View the comparison details between the source and target ends. Click on in the column on the right side of the comparison list (displayed when inconsistencies are found): Generate change SQL, you can directly copy this SQL to the target data source for execution, modifying the inconsistent content.
8	Expand	Display detailed information of the current replication task.

Appendix: Pre-Check Item List

Check Items	Check Contents
Verify if there are no primary key tables in the source database	Check if the object to be migrated does not have a primary key or unique key
Source datasource connection check	Check the status of the gateway of the source datasource, database connectable, and verify the username and password
Target datasource connection check	Check the status of the gateway of the target datasource, database connectable, and verify the username and password
Source database privilege check	Check whether the account privileges of the source database meet the requirements
Source database log_slave_updates check	When the source database is a slave, check whether log_slave_updates is ON
Source and target datasource version check	Check whether the source and target database versions are compatible
Check if the source database has Binlog enabled	Check if the source database has Binlog enabled
Source database binlog format check	Check whether the binlog format of the source database is 'ROW'
Source database binlog_row_image check	Check whether the binlog_row_image of the source database is 'FULL'
Cyclic replication check	Check for replication loops
Check the read-only status of the source database instance	Check the read-only status of the source database instance

Data Replication Introduction

MySQL Synchronization to Alibaba Cloud PolarDB-X

Feature Introduction​

Prerequisites​

Usage Limitations​

Operation Steps​

View Synchronization Results​

Appendix: Pre-Check Item List​

Related Documentation​