MySQL error when hard deleting a volume with a folder structure more than 15 levels deep

[angrybrad]

Description

https://dev.mysql.com/doc/refman/8.0/en/ansi-diff-foreign-keys.html

Cascading operations may not be nested more than 15 levels deep.

MySQL won't cascade delete/update more than 15 levels deep on foreign keys.

Where this tends to be a problem on the database side is on tables with hierarchy (parentId/childId) columns and can manifest itself with this error:

SQLSTATE[HY000]: General error: 1296 Got error 193

In Craft, this isn't a problem for structure sections, because when deleting, we start at the edge and recursively walk backward in code to perform the deletes.

But it can be an issue when deleting a volume with a deeply nested folder structure. We should perform the same logic we do for structure sections to volumes to work around this.