Re: [PATCH] Add support for displaying database service in psql prompt

On Tue, Jul 08, 2025 at 08:52:08AM +0900, Michael Paquier wrote:
> On Sun, Jul 06, 2025 at 08:00:09PM -0700, Noah Misch wrote:
> > I think the choice to make there is whether to call PQconninfo() once per
> > prompt emission or to cache the value, invalidating that cache e.g. once per
> > SyncVariables(). My first thought was to cache, but the decision is not too
> > important. A PQconninfo() call is likely negligible relative to all that
> > happens between prompts. Even if not negligible, the overhead of not caching
> > will affect only prompts using the new escape sequence.
>
> SyncVariables() happens at startup and when re-syncing a connection
> during a check, so that does not really worry me.
>
> By the way, there is a second change in the CF that's suggesting the
> addition of a SERVICEFILE variable, which also uses a separate libpq
> API (forgot about this one):
> https://commitfest.postgresql.org/patch/5387/
>
> Changing the patch on the other thread to use a conninfo is
> stright-forward. How about extending the get_service_name()@common.c
> I've proposed upthread so as it takes a string in input and it could
> be reused for more connection options than only "service" so as it
> could be reused there as well?

I'd prefer not to get involved in decisions affecting only psql efficiency and
psql code cosmetics. Please make that decision without my input.