Appears virtual folders are not purged if over >1000 Items are removed at once

[whyman]

Hello @whyman, thanks for a quick fix. Unfortunately fix had ripple effect uncovering another issue.

I built and installed gerbera from master, it shows me version 1.4.0alpha. With this version I executed the following test:

• previous sqite3 DB file removed
• gerbera started - it created new DB and populated it with fixed schema definition
• using web UI, music library imported
• in web UI FileSystem view, PC Directory top item with music library removed to purge the whole music library

<<snip>>

My idea why virtual folders were not purged:

My music library has more than 1000 items including containers. Note that MAX_REMOVE_SIZE is defined to 1000. When I removed top container from PC Directory, method SQLStorage::_recursiveRemove went down the tree to items. Items were planned for scan (itemIds vector), but before that, SQLStorage::_removeObjects was called for all containers and items. As FKs are active, ON DELETE CASCADE removes all records referencing containers and items by parent_id or ref_id. It means, all lists of virtual folder structure were removed before scan of itemIds vector. Once itemIds vector scan is executed all virtual list items are gone so virtual containers are not marked as changed.

Originally posted by @pcerny in https://github.com/gerbera/gerbera/issues/487#issuecomment-517987052

[whyman]

Quick note to say I've replicated this locally.

All the file nodes get removed, but the folder structure remains.