On Tue, Feb 28, 2017 at 6:22 AM, David Steele <da...@pgmasters.net> wrote: >>> I'm not sure that's the case. It seems like it should lock just as >>> multiple backends would now. One process would succeed and the others >>> would error. Maybe I'm missing something? >> >> Hm, any errors happening in the workers would be reported to the >> leader, meaning that even if one worker succeeded to run >> pg_start_backup() it would be reported as an error at the end to the >> client, no? By marking the exclusive function restricted we get sure >> that it is just the leader that fails or succeeds. > > Good point, and it strengthens the argument beyond, "it just seems right."
I think the argument should be based on whether or not the function depends on backend-private state that will not be synchronized. That's the definition of what makes something parallel-restricted or not. It looks like pg_start_backup() and pg_stop_backup() depend on the backend-private global variable nonexclusive_backup_running, so they should be parallel-restricted. -- Robert Haas EnterpriseDB: http://www.enterprisedb.com The Enterprise PostgreSQL Company -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
