Re: display hot standby state in psql prompt

Nathan Bossart <nathandbossart@gmail.com>

From: Nathan Bossart <nathandbossart@gmail.com>

To: Jim Jones <jim.jones@uni-muenster.de>

Cc: Fujii Masao <masao.fujii@gmail.com>, Srinath Reddy Sadipiralla <srinath2133@gmail.com>, Greg Sabino Mullane <htamfids@gmail.com>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>

Date: 2025-10-27T21:00:01Z

Lists: pgsql-hackers

Commits

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psql: Add %i prompt escape to indicate hot standby status.
- dddbbc253b92 19 (unreleased) landed
Mark search_path as GUC_REPORT
- 28a1121fd912 18.0 cited

On Mon, Oct 27, 2025 at 09:17:03PM +0100, Jim Jones wrote:
> On 27/10/2025 17:23, Nathan Bossart wrote:
>> This was briefly mentioned upthread, but I'm a little concerned that this
>> doesn't respond to commands like SET TRANSACTION READ ONLY.  I wonder if we
>> should mark transaction_read_only as GUC_REPORT and use that instead.  FWIW
>> I see that we marked search_path as GUC_REPORT somewhat recently (see
>> commit 28a1121).
> 
> You're right, it doesn't. I like the idea, but I'm not sure how to
> integrate a transaction-scoped variable into this feature. Would that
> mean we also need to change the reset mechanism for GUC_REPORT variables
> when the transaction ends?

Hm.  You're right, that seems to have problems (I'm curious about the use
of stmt->is_local in SetPGVariable() for SET TRANSACTION statements).  I
also see some past discussions in this area [0] [1] [2].

[0] https://postgr.es/m/flat/3a40f835-116d-0f95-aede-d5236337bbf0%402ndquadrant.com
[1] https://postgr.es/m/flat/CA%2BTgmoZsHrHeqh5dYpoH%2BWW5EmT-egMGuyrLTsjKz80WajT4tg%40mail.gmail.com
[2] https://postgr.es/m/flat/CAFj8pRBFU-WzzQhNrwRHn67N0Ug8a9-0-9BOo69PPtcHiBDQMA%40mail.gmail.com

-- 
nathan