Re: standby registration (was: is sync rep stalled?)

Robert Haas wrote:
> Yes, let's please just implement something simple and get it
> committed. k = 1. Two GUCs (synchronous_standbys = name, name, name
> and synchronous_waitfor = none|recv|fsync|apply), SUSET so you can
> change it per txn. Done. We can revise it *the day after it's
> committed* if we agree on how. And if we *don't* agree, then we can
> ship it and we still win.
>
I like the idea of something simple committed first, and am trying to
understand what's said above.

k = 1 : wait for only one ack
two gucs: does this mean configurable in postgresql.conf at the master,
and changable with SET commands on the master depending on options? Are
both gucs mutable?
synchronous_standbys: I'm wondering if this registration is necessary in
this simple setup. What are the named used for? Could they be removed?
Should they also be configured at each standby?
synchronous_waitfor: If configured on the master, how is it updated to
the standbys? What does being able to configure 'none' mean? k = 0? I
smell a POLA violation here.

regards
Yeb Havinga