Thread

Re: display hot standby state in psql prompt

Greg Sabino Mullane <htamfids@gmail.com> — 2025-06-26T00:52:06Z

On Wed, Jun 25, 2025 at 11:50 AM Jim Jones <jim.jones@uni-muenster.de>
wrote:

> Since I cannot get the value of transaction_read_only via
> PQparameterStatus.


Hmmm... we can at least get default_transaction_read_only. As fe-connect.c
points out:
                    /*
                     * "transaction_read_only = on" proves that at least one
                     * of default_transaction_read_only and in_hot_standby
is
                     * on, but we don't actually know which.  We don't care
                     * though for the purpose of identifying a read-only
                     * session, so satisfy the CONNECTION_CHECK_TARGET code
by
                     * claiming they are both on.  On the other hand, if
it's
                     * a read-write session, they are certainly both off.
                     */
Maybe that's good enough? It won't detect people starting a new transaction
and declaring it read-only, but it should be sufficient to warn people when
a connection is starting out in a read-only state. And it will still toggle
auto-magically on promotion.

Cheers,
Greg

--
Crunchy Data - https://www.crunchydata.com
Enterprise Postgres Software Products & Tech Support