Re: Understanding wal segments

On Thursday 01 November 2007 23:38:48 Tom Lane wrote:
> Kevin Kempter <kevin(at)kevinkempterllc(dot)com> writes:
> > Also I suspect after each filesystem backup I should remove the older
> > archived segments since the file system backup makes them
> > irrelevant. Is this accurate?
>
> Depends what your goals are. If you only want to be able to recover
> the latest database state then you only need archived WAL segments
> back to the start of the latest filesystem backup. If you are
> interested in the "PITR" aspect of it --- being able to revert back
> to last Tuesday before some bad guy injected bad data, say --- then
> you'll want to keep older filesystem backups too, and a continuous
> string of archived WAL files covering the period of interest.
>
> regards, tom lane
>
> ---------------------------(end of broadcast)---------------------------
> TIP 2: Don't 'kill -9' the postmaster

Makes sense. Thanks.

One more question. I see a fair amount of file changed warnings in the tar
output. Like this:

tar: ./data/base/82097725/4242350944: file changed as we read it
./data/base/82097725/143763179
./data/base/82097725/3587685114
./data/base/82097725/3587684991
./data/base/82097725/3587685046
./data/base/82097725/3587685003
./data/base/82097725/3588484372
tar: ./data/base/82097725/3588484372: file changed as we read it
./data/base/82097725/3587685172
./data/base/82097725/10733
./data/base/82097725/3588482971
./data/base/82097725/4082992388
./data/base/82097725/4242349291.4
tar: ./data/base/82097725/4242349291.4: file changed as we read it

Is this an issue or does postgres comensate for this since it knows I'm
running a backup (i've run a pg_start_backup) ?

Thx

/Kevin