Re: Printing LSN made easy

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.

            regards, tom lane