Horton

Re: display hot standby state in psql prompt

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

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From: Jim Jones <jim.jones@uni-muenster.de>
To: Fujii Masao <masao.fujii@gmail.com>
Cc: Srinath Reddy Sadipiralla <srinath2133@gmail.com>, Greg Sabino Mullane <htamfids@gmail.com>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2025-10-24T16:13:09Z
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 24/10/2025 17:21, Fujii Masao wrote:
> + const char *hs = PQparameterStatus(pset.db, "in_hot_standby");
> + const char *ro = PQparameterStatus(pset.db, "default_transaction_read_only");
> 
> When either hs or ro is NULL, the displayed status can be incorrect.
> For example, connecting to a standby server running PostgreSQL 10
> incorrectly shows "read/write". In such cases, wouldn't it be clearer
> to display something like "unknown", similar to how the "Hot Standby"
> column in \conninfo reports "unknown"?

Oh, it didn't occur to me to test this edge case. Thanks for the hint!

Would this be what you have in mind?

if (!hs || !ro)
    strlcpy(buf, "unknown", sizeof(buf));
else if ((hs && strcmp(hs, "on") == 0) ||
    (ro && strcmp(ro, "on") == 0))
	strlcpy(buf, "read-only", sizeof(buf));
else
    strlcpy(buf, "read/write", sizeof(buf));


Best, Jim