Added native UUID field type for MariaDB1070+

[juanparati]

Summary

MariaDB 10.7.0+ implements a native UUID field type (Guid) that works in similar way of Postgres UUID.

+Info: https://mariadb.com/kb/en/uuid-data-type/

[derrabus]

Thank you for your interest in contributing to the Doctrine project. However, we don't accept changes to our codebase that come without any tests. Furthermore, we don't accept any features on the 5.0.x branch. Please target 4.1.x instead.

Please be aware that supporting MariaDB's UUID type has been attempted before (#5990). The missing part here, as far as I remember, was the migration of UUID field with a foreign key constraint. You can continue that work if you like.

[juanparati]

@derrabus : I could provide a PR for 4.1.x. very quickly, however the migration part it's very tricky because it's not only about to modify char(36) to UUID type.

Depending of MariaDB version some UUID formats are not accepted (In version 10.9.8 UUIDs with version >= 8 and variant 0 are not accepted), UUIDs can be also migrated from binary(16) and char(32) (https://mariadb.org/10-7-preview-feature-uuid-data-type/).

[derrabus]

however the migration part it's very tricky because it's not only about to modify char(36) to UUID type.

Yes, it is the only case we need to cover. Columns that have been declared as UUID through the DBAL are CHAR(36) at the moment and once an app updates DBAL, it will try to migrate those columns to UUID. That's the case we need to handle properly.

UUIDs can be also migrated from binary(16)

That's out of scope. If someone used a BINARY(16) column to store their UUID, they won't have any trouble upgrading DBAL. Those binary columns will still work as they did before.

[juanparati]

I will take a look to the migration issue during this weekend.

Can you provide me any insights about where the migration test should be placed?

[derrabus]

Did you look into #5990?

[juanparati]

Yes, I got idea looking at 7673c87

I will try to work on that during next week.