Re: Updated backup APIs for non-exclusive backups

On 2/10/16 11:12 AM, Andres Freund wrote:
> On 2016-02-10 11:06:01 -0500, David Steele wrote:
>> That makes sense. The backup_label "as is" could be output at the
>> beginning but if we want to add the minimum recovery point it would need
>> to be output at the end.
>>
>> It seems like tablespace_map could still be output at the beginning, though.
>
> I don't really see enough benefit to go that way. What are you thinking
> of using the information for ("This would give the backup software more
> information to work with from the start.")?

Currently backup software that handles tablespaces needs to read the
pg_tblspc directory to build an oid/path mapping in order to know which
tablespace directories to copy. Since Postgres is already doing this
when it creates tablespace_map it seems like it's redundant for the
backup software to do it again.

Since tablespace_map is created in do_pg_start_backup() and I don't see
how it could be updated after that, I think it is logical to output it
from pg_start_backup(). I don't feel strongly about it, though.

--
-David
david(at)pgmasters(dot)net