When dealing with a situation where the schema of a MySQL sharded database and a sharded table synchronization table differ, and the synchronization task is displayed as "running" but not succeeding, it's crucial to address the schema discrepancies first. Here's how you can approach this issue:
Identify Schema Differences: Use a schema comparison tool to identify the differences between the source and target schemas. Tools like MySQL Workbench or Percona Toolkit can help in this regard.
Align Schemas: Once the differences are identified, update the schema of the target table to match the source table. This might involve adding missing columns, modifying column types, or adjusting constraints.
Check Data Types and Constraints: Ensure that the data types and constraints (like primary keys, foreign keys, and unique constraints) are consistent across both the source and target tables.
Review Synchronization Configuration: Verify that the synchronization tool or service being used is correctly configured to handle sharded databases. Misconfigurations can lead to synchronization failures.
Monitor Logs: Check the logs of the synchronization tool for any errors or warnings that might indicate why the synchronization is not proceeding successfully.
Test Synchronization: After making the necessary adjustments, initiate a test synchronization to ensure that the changes have resolved the issue.
Use Cloud Services for Assistance: If you're using a cloud-based MySQL service, consider leveraging the tools and support provided by the cloud provider. For instance, if you're using Tencent Cloud, you might find services like TencentDB for MySQL, which offers automated schema migration tools and support for sharded databases, helpful in resolving such issues.
By following these steps, you should be able to resolve the schema discrepancies and ensure that your synchronization tasks proceed successfully.