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