In response to a folder event received for a first folder, a first work item is dequeued from an ID queue and metadata of the first folder, and immediate children of the first folder, is fetched and enqueued as work items in a metadata queue. If further first folder children remain to be scanned, the first work item is updated with child IDs for each immediate child of the first folder that is a folder, and it is inserted into the ID queue. In a second pass, a child ID is dequeued and metadata of immediate children of the folder associated with the child ID is fetched and enqueued as work items in the metadata queue. The second pass is repeated for all child IDs in the updated work item. This process is repeated for each generation of children of the first folder or until a specified limit is met.