Hi, I am interested in how the system time is synced across nodes. I pass a presto query like

date > now() - interval'30' minute

to pinot. How much I can be sure about the "now()" function? Is it be translated to a exact time in presto and then pass to pinot? Then how much difference it can have across different pinot nodes?

Good question, now() is computed at the broker that receives the query. And then all the servers go by that time.

Do we have any mechanism in Pinot that sync the time across different brokers? Or it just assume the system time is up-to-date and sync across each server? And something else should keep the system time up-to-date.

yes, we assume the system time is up-to-date across all brokers.