Re: Postgres-R: internal messaging

Markus Wanner <markus@bluegap.ch> writes:
> ... crashes are more difficult. IMO the replication 
> manager needs to stay alive during this reinitialization, to keep the 
> GCS connection. However, it can easily detach from shared memory 
> temporarily (the imessages stuff is the only shmem place it touches, 
> IIRC). However, a more difficult aspect is: it must be able to tell if a 
> backend has applied its transaction *before* it died or not. Thus, after 
> all backends have been killed, the postmaster needs to wait with 
> reinitializing shared memory, until the replication manager has consumed 
> all its messages. (Otherwise we would risk "losing" local transactions, 
> probably also remote ones).

I hope you're not expecting the contents of shared memory to still be
trustworthy after a backend crash.  If the manager is working strictly
from its own local memory, then it would be reasonable to operate
as above.
        regards, tom lane