Re: Support for N synchronous standby servers - take 2

On 07/06/2015 06:40 PM, Michael Paquier wrote:
> On Tue, Jul 7, 2015 at 2:56 AM, Josh Berkus <josh@agliodbs.com> wrote:
>> pro-JSON:
>>
>> * standard syntax which is recognizable to sysadmins and devops.
>> * can use JSON/JSONB functions with ALTER SYSTEM SET to easily make
>> additions/deletions from the synch rep config.
>> * can add group labels (see below)
> 
> If we go this way, I think that managing a JSON blob with a GUC
> parameter is crazy, this is way longer in character size than a simple
> formula because of the key names. Hence, this JSON blob should be in a
> separate place than postgresql.conf not within the catalog tables,
> manageable using an SQL interface, and reloaded in backends using
> SIGHUP.

I'm not following this at all.  What are you saying here?

>> I don't really see any possible end to the possible permutations, which
>> is why it would be good to establish some real use cases from now in
>> order to figure out what we really want to support.  Absent that, my
>> inclination is that we should implement the simplest possible thing
>> (i.e. no nesting) for 9.5.
> 
> I am not sure I agree that this will simplify the work. Currently
> s_s_names has already 1 level, and we want to append groups to each
> element of it as well, meaning that we'll need at least 2 level of
> nesting.

Well, we have to draw a line somewhere, unless we're going to support
infinite recursion.

And if we are going to support infinitie recursion, and kind of compact
syntax for a GUC isn't even worth talking about ...


-- 
Josh Berkus
PostgreSQL Experts Inc.
http://pgexperts.com