Re: [GENERAL] Incremental / Level -1 backup in PG

On 3/22/2017 10:34 AM, Rakesh Kumar wrote:
> When the PITR is far apart from the time of base backup (far apart as in, let us
> say 4 to 5 days), the first approach beats the second approach hands down. This
> coming from experience. Reason is simple. In the second approach every transaction
> (from the time of base backup) has to applied to roll-foward to PIT. In incremental backup,
> a block is only applied once, regardless of how many times it changed after the base backup.

note postgres' WAL archive is by block, not by transaction.  also note
that postgres effectively does copy-on-write, since update's are treated
as insert+delete, so the same blocks aren't written over and over nearly
as much as they might be in the oracle storage model.


--
john r pierce, recycling bits in santa cruz