Re: [PATCH] Stop ALTER SYSTEM from making bad assumptions

On 6/19/19 12:46 PM, Amit Kapila wrote:
> On Mon, Jun 17, 2019 at 8:20 PM Ian Barwick <ian(dot)barwick(at)2ndquadrant(dot)com> wrote:
>> On 6/15/19 1:08 AM, Stephen Frost wrote:
>> > * Amit Kapila (amit(dot)kapila16(at)gmail(dot)com) wrote:
>> >> Right. I think if possible, it should use existing infrastructure to
>> >> write to postgresql.auto.conf rather than inventing a new way to
>> >> change it. Apart from this issue, if we support multiple ways to edit
>> >> postgresql.auto.conf, we might end up with more problems like this in
>> >> the future where one system is not aware of the way file being edited
>> >> by another system.
>> >
>> > I agere that there should have been some effort put into making the way
>> > ALTER SYSTEM is modified be consistent between the backend and utilities
>> > like pg_basebackup (which would also help third party tools understand
>> > how a non-backend application should be modifying the file).
>>
>> Did you mean to say "the way postgresql.auto.conf is modified"?
>>
>
> Yes, that is what we are discussing here. I think what we can do here
> is to extract the functionality to set the parameter in .auto.conf
> from AlterSystemSetConfigFile and expose it via a function that takes
> (option_name, value) as a parameter.

Yup, I was just considering what's involved there, will reply to another
mail in the thread on that.

> Then we can expose it via some
> SQL function like set_auto_config (similar to what we have now for
> set_config/set_config_by_name). I think if we have something like
> that then pg_basebackup or any other utility can use it in a
> consistent way.

Umm, but the point is here, the server will *not* be running at this point,
so calling an SQL function is out of the question. And if the server
is running, then you just execute "ALTER SYSTEM".

Regards

Ian Barwick

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Ian Barwick https://www.2ndQuadrant.com/
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