Re: pg_upgrade and rsync

On 1/22/15 10:05 PM, Stephen Frost wrote:
>> In addition, there is a possible race condition in rsync where a file
>> that is modified in the same second after rsync starts to copy will not
>> be picked up in a subsequent rsync unless --checksum is used. This is
>> fairly easy to prove and is shown here:
>>
>> https://github.com/pgmasters/backrest/blob/dev/test/lib/BackRestTest/BackupTest.pm#L1667
> Right, though that isn't really an issue in this specific case- we're
> talking about post-pg_upgrade but before the upgraded cluster has
> actually been started, so nothing should be modifying these files.

Indeed. This was really directed more at what Bruce said:

I am thinking the fix for standys would be similar to what we recommand
for upgrades with link mode using a rsync-created copy, e.g. use rsync
while the master is running to create a copy of the standby, then shut
down the master and run rsync again. However, at that point, you might
as well just take a base backup and be done with it.

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