Re: Printing LSN made easy

On Mon, Nov 30, 2020 at 1:10 AM Tom Lane <tgl@sss.pgh.pa.us> wrote:

> Michael Paquier <michael@paquier.xyz> writes:
> > On Fri, Nov 27, 2020 at 04:10:27PM +0530, Ashutosh Bapat wrote:
> >> Off list Craig Ringer suggested introducing a new format specifier
> >> similar to %m for LSN but I did not get time to take a look at the
> >> relevant code. AFAIU it's available only to elog/ereport, so may not
> >> be useful generally. But teaching printf variants about the new format
> >> would be the best solution. However, I didn't find any way to do that.
>
> > -1.  %m maps to errno, that is much more generic.  A set of macros
> > that maps to our internal format would be fine enough IMO.
>
> Agreed.  snprintf.c is meant to implement a recognized standard
> (ok, %m is a GNU extension, but it's still pretty standard).
> I'm not on board with putting PG-only extensions in there.
>

Fair enough. I did not realise that %m was a GNU extension (never looked
closely) so I thought we had precedent for Pg specific extensions there.

Agreed in that case, no argument from me.