sizeOnDisk in listDatabases
What changes in sizeOnDisk in listDatabases compared with MongoDB and what your application has to do.
This difference is of the Different kind.
What MongoDB does
sizeOnDisk is the compressed size each database takes in WiredTiger.
What TeselaDB does
sizeOnDisk counts the bytes of stored keys and documents in 4 KiB blocks. admin and config always appear, with at least 8192 bytes.
What your application has to do
Do not compare sizeOnDisk with MongoDB's to plan disk; look at the space of the data directory.