Re: [PATCH v1] Add and report the new "in_hot_standby" GUC pseudo-variable.

On 18 March 2017 at 14:01, Elvis Pranskevichus <elprans(at)gmail(dot)com> wrote:
> On Saturday, March 18, 2017 3:33:16 AM EDT Michael Paquier wrote:
>>
>> Why adding a good chunk of code instead of using pg_is_in_recovery(),
>> which switches to false once a server exits recovery?
>
> That requires polling the database continuously, which may not be
> possible or desirable.
>
> My main motivation here is to gain the ability to manage a pool of
> connections in asyncpg efficiently. A part of the connection release
> protocol is "UNLISTEN *;", which the server in Hot Standby would fail to
> process. Polling the database for pg_is_in_recovery() is not feasible
> in this case, unfortunately.
>

Sorry, i still don't understand the motivation for this.
At one point you're going to poll for the value of the GUC in pg_settings, no?
Or how are you going to know the current value of the GUC that makes it
different to just poll for pg_is_in_recovery()?

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