Re: Sync Rep: First Thoughts on Code

"Robert Haas" <robertmhaas(at)gmail(dot)com> writes:
> I think we need to reserve the term "synchronous replication" for a
> system where transactions that begin at the same time on the primary
> and standby see the same tuples. Clearly that is "more" synchronous
> than what is being proposed here; if we call this "synchronous
> replication", what will we call that? "Really Synchronous, Honest, No
> Kidding"? Admittedly, we may never implement that feature, but that
> seems irrelevant.

We won't call it anything, because we never will or can implement that.
See the theory of relativity: the notion of exactly simultaneous events
at distinct locations isn't even well-defined, because observers at yet
other locations will disagree about what is "simultaneous". And I'm
not just making a joke here --- speed-of-light delays in a WAN are
meaningful compared to current computer speeds. In practice, the
slave and the master will never commit at exactly the same time.

I agree with the point made upthread that we should use the term
"synchronous replication" the way it's commonly used in the industry.
Inventing our own terminology might be fun but it's not really going
to result in less confusion.

regards, tom lane