Re: point in time recovery and moving datafiles online

Tatsuo Ishii <t-ishii(at)sra(dot)co(dot)jp> writes:
>> No. It is not reasonable to expect the backup to allow you to recreate
>> any state occurring before the *end* of the backup process.

> I see your point. But is it reasonable? We cannot know when the backup
> process completes beforehand and that makes the archive log recovery
> less usefull in my opinion.

So? The backup will not let you recover states occurring before it
starts, either. I don't see the issue. Anyone using this in a
production situation will *always* have a prior backup and a continuous
WAL trail since the start of the prior backup. Whether the
synchronization point is the start time or end time of each new backup
isn't a hot issue for them --- at least it shouldn't be if they are
following appropriate procedures.

The only way I can see to make it work the other way is to dump the
entire contents of any to-be-deleted table into the WAL log before
deleting it. That is way too much overhead to be a reasonable tradeoff
for letting people think of the start time rather than end time of their
backups as the cutover point.

regards, tom lane