Re: Remove Deprecated Exclusive Backup Mode

Laurenz Albe <laurenz.albe@cybertec.at>

From: Laurenz Albe <laurenz.albe@cybertec.at>

To: Stephen Frost <sfrost@snowman.net>, Christophe Pettus <xof@thebuild.com>

Cc: Robert Haas <robertmhaas@gmail.com>, Fujii Masao <masao.fujii@gmail.com>, David Steele <david@pgmasters.net>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>

Date: 2019-02-24T21:14:42Z

Lists: pgsql-hackers

Commits

Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →

Remove exclusive backup mode
- 39969e2a1e4d 15.0 landed

Stephen Frost wrote:
> Yes, it *is* impossible to do safe backups with the existing API.  There
> is an unquestionable race condition where a system restart will cause
> your system to not come back up without you going in and removing the
> backup_label file- and the only way you make that race window small is
> to remove the backup_label file right after you run pg_start_backup and
> copy it, and then PUT IT BACK at the end before you call pg_stop_backup,
> which is insane, but otherwise the 'race window' is the ENTIRE length of
> the backup.

I just have an idea:

What about an option to keep WAL around for the duration of an exclusive backup?

That way PostgreSQL can still restart after a crash.  It will take longer than
expected, but it will work.  But then, perhaps the long recovery time is only
marginally better than having to manually delete the backup_label file...

Yours,
Laurenz Albe