Re: What is a typical precision of gettimeofday()?

On 19.03.24 10:38, Aleksander Alekseev wrote:
> Considering the number of environments PostgreSQL can run in (OS +
> hardware + virtualization technologies) and the fact that
> hardware/software changes I doubt that it's realistic to expect any
> particular guarantees from gettimeofday() in the general case.

If we want to be robust without any guarantees from gettimeofday(), then 
arguably gettimeofday() is not the right underlying function to use for 
UUIDv7.  I'm not arguing that, I think we can assume some reasonable 
baseline for what gettimeofday() produces.  But it would be good to get 
some information about what that might be.

Btw., here is util-linux saying

     /* Assume that the gettimeofday() has microsecond granularity */

https://github.com/util-linux/util-linux/blob/master/libuuid/src/gen_uuid.c#L232