Re: Remove Deprecated Exclusive Backup Mode

David Steele <david@pgmasters.net>

From: David Steele <david@pgmasters.net>

To: Robert Haas <robertmhaas@gmail.com>, Magnus Hagander <magnus@hagander.net>

Cc: Stephen Frost <sfrost@snowman.net>, Laurenz Albe <laurenz.albe@cybertec.at>, PostgreSQL Developers <pgsql-hackers@lists.postgresql.org>

Date: 2020-07-01T20:34:21Z

Lists: pgsql-hackers

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Remove exclusive backup mode
- 39969e2a1e4d 15.0 landed

On 7/1/20 4:27 PM, David Steele wrote:
> 
> Here's a thought. What if we just stored the oldest starting LSN and a 
> count of how many backups have been requested. When the backup ends it 
> checks that backup count is > 0 and starting LSN is <= its starting LSN. 
> If not, it throws an error. When backups go to 0 FPWs are turned off if 
> they were off before the first backup.

To be clear, the min starting LSN only needs to be reset when 
incrementing total running backups from 0 to 1. What we are recording 
here is the LSN since FPWs were enabled. As long as it is <= the start 
LSN of the backup when it ends then all is well (I think).

Regards,
-- 
-David
david@pgmasters.net