| From: | "Tsunakawa, Takayuki" <tsunakawa(dot)takay(at)jp(dot)fujitsu(dot)com> |
|---|---|
| To: | 'Dave Cramer' <pg(at)fastcrypt(dot)com> |
| Cc: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Robert Haas <robertmhaas(at)gmail(dot)com>, "laurenz(dot)albe(at)cybertec(dot)at" <laurenz(dot)albe(at)cybertec(dot)at>, Haribabu Kommi <kommi(dot)haribabu(at)gmail(dot)com>, Jing Wang <jingwangian(at)gmail(dot)com>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | RE: Libpq support to connect to standby server as priority |
| Date: | 2019-01-16 04:20:16 |
| Message-ID: | 0A3221C70F24FB45833433255569204D1FB682DB@G01JPEXMBYT05 |
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| Lists: | pgsql-hackers |
From: Dave Cramer [mailto:pg(at)fastcrypt(dot)com]
> The original desire should have been the ability to connect to a
> primary or a standby. So, I think we should go back to the original thinking
> (and not complicate the feature), and create a read only GUC_REPORT variable,
> say, server_role, that identifies whether the server is a primary or a
> standby.
>
>
>
> I'm confused as to how this would work. Who or what determines if the server
> is a primary or standby?
Overall, the server determines the server role (primary or standby) using the same mechanism as pg_is_in_recovery(), and set the server_role GUC parameter. As the parameter is GUC_REPORT, the change is reported to the clients using the ParameterStatus ('S') message. The clients also get the value at connection.
Regards
Takayuki Tsunakawa
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