Horton

Re: Use of backup_label not noted in log

Laurenz Albe <laurenz.albe@cybertec.at>

View thread View on postgr.es
From: Laurenz Albe <laurenz.albe@cybertec.at>
To: Andres Freund <andres@anarazel.de>, pgsql-hackers@postgresql.org, Michael Paquier <michael.paquier@gmail.com>, David Steele <david@pgmasters.net>
Date: 2023-11-17T05:41:46Z
Lists: pgsql-hackers 
On Thu, 2023-11-16 at 20:18 -0800, Andres Freund wrote:
> I've often had to analyze what caused corruption in PG instances, where the
> symptoms match not having had backup_label in place when bringing on the
> node. However that's surprisingly hard - the only log messages that indicate
> use of backup_label are at DEBUG1.
> 
> Given how crucial use of backup_label is and how frequently people do get it
> wrong, I think we should add a LOG message - it's not like use of backup_label
> is a frequent thing in the life of a postgres instance and is going to swamp
> the log.  And I think we should backpatch that addition.

+1

I am not sure about the backpatch: it is not a bug, and we should not wantonly
introduce new log messages in a minor release.  Some monitoring system may
get confused.

What about adding it to the "redo starts at" message, something like

  redo starts at 12/12345678, taken from control file

or

  redo starts at 12/12345678, taken from backup label

Yours,
Laurenz Albe

Commits

  1. Add more LOG messages when starting and ending recovery from a backup