From: | Robert Haas <robertmhaas(at)gmail(dot)com> |
---|---|
To: | David Steele <david(at)pgmasters(dot)net> |
Cc: | Michael Paquier <michael(dot)paquier(at)gmail(dot)com>, Pg Hackers <pgsql-hackers(at)postgresql(dot)org> |
Subject: | Re: PATCH: Make pg_stop_backup() archive wait optional |
Date: | 2017-03-01 03:22:28 |
Message-ID: | CA+TgmoYCWfO2UM-t=HUMFJyxJywLDiLL0nAJpx88LKtvBvNECw@mail.gmail.com |
Views: | Raw Message | Whole Thread | Download mbox | Resend email |
Thread: | |
Lists: | pgsql-hackers |
On Tue, Feb 28, 2017 at 6:22 AM, David Steele <david(at)pgmasters(dot)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
From | Date | Subject | |
---|---|---|---|
Next Message | Corey Huinker | 2017-03-01 03:22:58 | Re: some dblink refactoring |
Previous Message | Peter Eisentraut | 2017-03-01 03:21:18 | Re: cast result of copyObject() |