Duncan Kinnear wrote: > Bingo! Adding 'SET LOCAL synchronous_commit TO OFF;' to my 'BEGIN; UPDATE ....; COMMIT;' > block has given me sub-1ms timings! Thanks Andres. That's a pretty clear indication that your I/O subsystem was overloaded. Yours, Laurenz Albe -- Cybertec | https://www.cybertec-postgresql.com