On Wed, Mar 1, 2017 at 9:07 AM, David Steele <da...@pgmasters.net> wrote: > On 2/28/17 10:22 PM, Robert Haas wrote: >> 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. > > Absolutely. Yesterday was a long day so I may have (perhaps) become a > bit flippant. > >> 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. > > Agreed.
How about a separately-committable patch that just does that, and then a main patch that applies on top of it? -- 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
