Comment 2 for bug 1988421

Hey Brian,

well the warning originates from MySQL/MariaDB, see https://mariadb.com/docs/reference/mdb/error-codes/ER_DUP_INDEX/ or "1831" on https://mariadb.com/kb/en/mariadb-error-codes/. It just happen during DDL SQL statements modifing the schemas, but it's actually just MariaDB complaining.

I tried to manually reproduce the warning by creating a regular and a unique index on the same columns, but MariaDB 10.6.8 would only complain if both were either regular indexes or a both unique indexes.

In any case a unique index is more specific and should be all you need. In the referenced case of Nova (https://bugs.launchpad.net/nova/+bug/1641185) there it's actually two unique indexes being created on the exact same column "uuid" (no pun intended).

If you look at their code at https://opendev.org/openstack/nova/src/commit/c53ec4e48884235566962bc934cbf292ad5b67b8/nova/db/main/models.py#L269 they simply marked the column as unique in the first place and did also add a unique index.

Maybe it's cleaner code to just mark a column unique and don't bother with an additional constraint?

Would you consider dropping the additional index in the neutron case then?