I tried pasting a reverse replica from Amazon Aurora MySQL v3 to v2 and it worked.
This is Oniumi (@fat47) from the Service Reliability Group (SRG) of the Technology Headquarters.
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I hope this helps in some way.
!! Note !!Reverse replica?In plain MySQL, if you try to replicate in the opposite direction, an error will occur.Why is Aurora MySQL okay?Conclusion
!! Note !!
The contents of this article are configurations that are not recommended from both MySQL and AWS perspectives.
Please note that this is just a report that it worked.
Reverse replica?
Aurora Version 3 is the source and Version 2 is the replica, and replication is being done between clusters.
When upgrading from v2, we will provide a replication of the reverted version in case you want to switch back to v2, although this is not recommended.
In plain MySQL, if you try to replicate in the opposite direction, an error will occur.
I've written about this in the past on my blog.
If you set up replication with MySQL 8.0 as the source and MySQL 5.7 as the replica, the replication will immediately stop with an error.
@@session.collation_connection=255To avoid this, you need to fix the default behavior of collation to utf8_general_ci by specifying the following in the MySQL 8.0 configuration.
By the way, the default_collation_for_utf8mb4 setting cannot be applied in Aurora.
Why is Aurora MySQL okay?
Here are some excerpts from past articles:
Aurora Version 2 (compatible with MySQL 5.7) has its own implementation of the collation utf8mb4_0900_ai_ci, which is not included in the original MySQL 5.7.
Therefore, even if you configure replication with Aurora v3 as the source and Aurora v2 as the replica,
Collation errors do not stop replication.
Conclusion
Please note that these are not recommended methods.
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