Re: Updated backup APIs for non-exclusive backups

On 4/24/16 11:49 AM, Stephen Frost wrote:
> * Magnus Hagander (magnus(at)hagander(dot)net) wrote:
>> On Sun, Apr 24, 2016 at 5:37 AM, Bruce Momjian <bruce(at)momjian(dot)us> wrote:
>>
>>> On Fri, Apr 22, 2016 at 11:53:46AM -0400, Robert Haas wrote:
>>>
>>>> Frankly, I think that's right. It is one thing to say that the new
>>>> method is preferred - +1 for that. But the old method is going to
>>>> continue to be used by many people for a long time, and in some cases
>>>> will be superior. That's not something we can deprecate, unless I'm
>>>> misunderstanding the situation.
>>>
>>> I agree with Robert. One the one hand we are saying pg_stop_backup()
>>> doesn't work well in psql because you get those two file contents output
>>> that you have to write, and on the other hand we are saying we are going
>>> to deprecate the method that does work well in psql? I must be missing
>>> something too, as that makes no sense.
>>
>> I don't agree. I don't see how "making a backup using psql" is more
>> important than "making a backup without potentially dangerous sideeffects".
>> But if others don't agree, could one of you at least provide an example of
>> how you'd like the docs to read in a way that doesn't deprecate the unsafe
>> way but still informs the user properly?
>
> I'm with Magnus on this, primairly because I've come to understand just
> how dangerous the old backup method is. That method *should* be
> deprecated and discouraged. A backup method which means your database
> doesn't restart properly if the system crashes during the backup is
> *bad*.

+1

> Perhaps we can look at improving psql to make it easier to use it for
> the new backup method but, honestly, all these hackish scripts to do
> backups aren't doing a lot of things that a real backup solution needs
> to do. Improving psql for this is a bit like new paint on the titanic.

Personally I think we do the users a disservice by implying that backup
is as simple as calling two functions and copying the files. Oh, and
don't forget to include WAL!

--
-David
david(at)pgmasters(dot)net