Photos version 4 database
The full schema for Photos 4 databases can be found here.
Sort order of photos in albums is not yet supported by osxphotos. The sort order appears to be in table RKCustomSortOrder.
The highlighted rows in screenshot below show 4 photos in an album with default sort order. Note the orderNumber column uses a similar scheme as in Catalina (start at 1024 and increment by 2^10). containerUuid is the album UUID (RKAlbum.uuid) and objectUuid is the photo UUID (RKVersion.uuid).
In screenshot below, I manually re-sorted the images, moving the second to last image (uuid = 6bxcNnzRQKGnK4uPrCJ9UQ) to the beginning of the album. Note it's orderNumber changed from 3072 to 1536, placing it first in the album.
