Re: Allowing multiple concurrent base backups

Heikki Linnakangas <heikki(dot)linnakangas(at)enterprisedb(dot)com> writes:
> I implemented this in two ways, and can't decide which I like better:

> 1. The contents of the backup label file are returned to the caller of
> do_pg_start_backup() as a palloc'd string.

> 2. do_pg_start_backup() creates a temporary file that the backup label
> is written to (instead of "backup_label").

> Implementation 1 changes more code, as pg_start/stop_backup() need to be
> changed to write/read from memory instead of file, but the result isn't
> any more complicated. Nevertheless, I somehow feel more comfortable with 2.

Seems like either one of these is fairly problematic in that you have to
have some monstrous kluge to get the backup_label file to appear with
the right name in the tarfile. How badly do we actually need this?
I don't think the use-case for concurrent base backups is all that large
in practice given the I/O hit it's going to involve.

regards, tom lane