Re: Updated backup APIs for non-exclusive backups

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От David Steele
Тема Re: Updated backup APIs for non-exclusive backups
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Msg-id 5383f4e3-ff19-7429-1030-7d5c89585d15@pgmasters.net
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Ответ на Re: Updated backup APIs for non-exclusive backups  (Stephen Frost <sfrost@snowman.net>)
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On 4/24/16 11:49 AM, Stephen Frost wrote:
> * Magnus Hagander (magnus@hagander.net) wrote:
>> On Sun, Apr 24, 2016 at 5:37 AM, Bruce Momjian <bruce@momjian.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@pgmasters.net


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