Re: [GENERAL] "Resurrected" data files - problem?

From: Tom Lane <tgl(at)sss.pgh.pa.us>
Date: Fri Nov 09 2007 - 10:59:14 EST

Simon Riggs <simon@2ndquadrant.com> writes:

> On Fri, 2007-11-09 at 10:28 +0100, Albe Laurenz wrote:

>> I think that understanding is finally dawning here.
>>
>> The problem you see is that the backup software might decide
>> that the file has not been changed, skip it and go on backing
>> up other files, but the file can still be modified before
>> pg_stop_backup(), correct?

> Correct.

Surely that's nonsense --- otherwise a time-extended base backup could not work either.

What is required of the filesystem backup process is that each 8K page of each file be restored to a state that it had at some time between pg_start_backup and pg_stop_backup. The exact time can be different for different pages. I don't see a reason to think that a base+incremental backup method can't meet that requirement.

                        regards, tom lane

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