Percona Server 5.7.21-21 has fast upserts for tokudb! We’ve been waiting for this feature with bated breath.
However, despite enabling both tokudb_enable_fast_update and tokudb_enable_fast_upsert we can’t see any change in upsert speed 
We’ve tried upserting a few thousand rows at a time, using REPLACE INTO or INSERT INTO ON UPDATE overwrite.
Do these new variables do anything and what do we have to do in our sql to trigger a faster upsert?
Its all a bit perplexing; the old tokudb as packaged by tokutek used to knock the socks off all the other storage engines for upsert speed. Modern percona is nowhere near the speed of the old and now the NOAR work seems to not actually change anything either