Spill counters
What changes in Spill counters compared with MongoDB and what your application has to do.
This difference is of the Different kind.
What MongoDB does
When a stage spills to disk, it cuts small chunks and compresses them.
What TeselaDB does
usedDisk comes out as in MongoDB, but the spill counters count chunks the size of the stage's limit, uncompressed.
What your application has to do
Look at usedDisk to know whether a query spilled; do not compare the other counters.