Horton

Re: display hot standby state in psql prompt

Fujii Masao <masao.fujii@gmail.com>

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From: Fujii Masao <masao.fujii@gmail.com>
To: Jim Jones <jim.jones@uni-muenster.de>
Cc: Andreas Karlsson <andreas@proxel.se>, Nathan Bossart <nathandbossart@gmail.com>, Srinath Reddy Sadipiralla <srinath2133@gmail.com>, Greg Sabino Mullane <htamfids@gmail.com>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>, Chao Li <li.evan.chao@gmail.com>
Date: 2025-11-12T03:48:43Z
Lists: pgsql-hackers

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Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →

  1. psql: Add %i prompt escape to indicate hot standby status.

  2. Mark search_path as GUC_REPORT

On Mon, Nov 10, 2025 at 5:14 PM Jim Jones <jim.jones@uni-muenster.de> wrote:
>
>
>
> On 10/11/2025 08:30, Fujii Masao wrote:
> > If the main goal of this feature is to help users easily determine
> > whether they're connected to a primary or a standby,
> > seems simply showing whether the server is in hot standby
> > should be sufficient. I'm not sure how useful it would be in practice
> > to show information based on default_transaction_read_only or
> > transaction_read_only.
>
> This "primary" or "standby" approach was actually the initial proposal,
> but it evolved after a few reviews. Extending it to use
> transaction_read_only and default_transaction_read_only adds real value
> to the feature, but doing so requires either:
>
> 1. Marking transaction_read_only as GUC_REPORT (controversial and
> rejected in the past), or
> 2. Querying transaction_read_only with SHOW every time the prompt is
> displayed within a transaction block (IMO minimal overhead -- but
> unconventional?).
>
> Although I lean toward the initial proposal, I can totally live with
> either approach, since both would be able to distinguish if a server is
> in hot standby or not.
>
> Should we switch back to the initial proposal?

I'm fine with the initial proposal. I think showing whether the connected
server is a primary or standby in the prompt would be helpful when managing
multiple servers. OTOH, I'm not sure how useful it would be to display
whether the current transaction is read-only.

That said, this is just my view, so I'd like to hear what others think.

Regards,

-- 
Fujii Masao