RE: Libpq support to connect to standby server as priority

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
Views: Raw Message | Whole Thread | Download mbox | Resend email
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.

Takayuki Tsunakawa

In response to


Browse pgsql-hackers by date

  From Date Subject
Next Message Tom Lane 2019-01-16 04:37:30 Re: Proving IS NOT NULL inference for ScalarArrayOpExpr's
Previous Message Mithun Cy 2019-01-16 03:54:57 Re: WIP: Avoid creation of the free space map for small tables