(Cockroach Labs CTO here) > > But you don't need an atomic clock to get Spanner's guarantees. This comment continues "...but GPS clock-sources will do just fi

(Cockroach Labs CTO here) > > But you don't need an atomic clock to get Spanner's guarantees. This comment continues "...but GPS clock-sources will do just fine for Spanner's 6ms quantum". Providing Spanner's guarantees with reasonable performance requires specialized hardware, but there are more options for that specialized hardware than just atomic clocks. Note that Spanner itself uses both atomic and GPS time sources according to Google's publications; when we talk about "atomic clocks" we're usually talking about the entire category of specialized time-keeping hardware instead of distinguishing atomic clocks from GPS clocks. > I always hear this from CockroachDB folks and fans, but no details. What are the downsides? As we describe in our blog post (https://www.cockroachlabs.com/blog/living-without-atomic-clocks/ https://www.cockroachlabs.com/blog/living-without-atomic-clo...), CockroachDB on commodity hardware provides a slightly weaker consistency model than Spanner (serializable instead of linearizable), and latency is sometimes higher as we need to account for the larger clock offsets in certain situations. If you do have a high-quality time source available, we have an experimental option to use a Spanner-like linearizable mode.