Re: Why is vacuum_freeze_min_age 100m?

"Kevin Grittner" <Kevin(dot)Grittner(at)wicourts(dot)gov> writes:
> Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>> (2) there's not really much to be gained by reducing it.

> That depends. The backup techniques I recently posted, using hard
> links and rsync, saved us the expense of another ten or twenty TB of
> mirrored SAN archival storage space, and expensive WAN bandwidth
> upgrades. In piloting this we found that we were sending our
> insert-only data over the wire twice -- once after it was inserted and
> once after it aged sufficiently to be frozen. Aggressive freezing
> effectively cut our bandwidth and storage needs for backup down almost
> by half. (Especially after we made sure we left enough time for the
> VACUUM FREEZE to complete before starting that night's backup
> process.)

Hmmm ... if you're using VACUUM FREEZE, its behavior is unaffected by
this GUC anyway --- that option makes it use a freeze age of zero.

regards, tom lane