Re: Synchronous Standalone Master Redoux

On Wed, Jul 11, 2012 at 3:03 AM, Dimitri Fontaine
<dimitri(at)2ndquadrant(dot)fr> wrote:
> Daniel Farina <daniel(at)heroku(dot)com> writes:
>> Notable caveat: one can't very easily measure or bound the amount of
>> transaction loss in any graceful way as-is. We only have "unlimited
>> lag" and "2-safe or bust".
>
> ¡per-transaction!
>
> You can change your mind mid-transaction and ask for 2-safe or bust.
> That's the detail we've not been talking about in this thread and makes
> the whole solution practical in real life, at least for me.

It's a pretty good feature, but it's pretty dissatisfying that one
cannot have the latency of asynchronous transactions while not
exposing users to unbounded loss as an administrator or provider (as
opposed to a user that sets synchronous commit, as you are saying).

If I had a strong opinion on *how* this should be tunable, I'd voice
it, but I think it's worth insisting that there is a missing part of
this continuum that involves non-zero but not-unbounded risk
management and transaction loss that is under-served. DRBD seems to
have some heuristic that makes people happy that's somewhere
in-between. I'm not saying it should be copied, but the fact it makes
people happy may be worth understanding.

I was quite excited for the syncrep feature because it does open the
door to write those, even if painfully, at all, since we now have both
"unbounded" and "strictly bounded".

--
fdr