I tried replicating from Amazon Aurora MySQL v3 to v2 in the reverse direction 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 occurs.Why is Aurora MySQL okay?Conclusion
!! Note !!
The contents of this article are not recommended configurations 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 established between clusters.
When upgrading from v2, we will provide a replication of the reversed version, although this is not recommended, in case you want to revert to v2.
In plain MySQL, if you try to replicate in the opposite direction, an error occurs.
I've written about this on my blog in the past.
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 to Aurora.
Why is Aurora MySQL okay?
Here are some excerpts from previous 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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