Re: block-level incremental backup

On Thu, Apr 11, 2019 at 12:22 AM Michael Paquier <michael@paquier.xyz> wrote:
> incremental page size is reduced in the actual backup.  My preference
> tends toward a block-level approach if we were to do something in this
> area, though I fear that performance will be bad if we begin to scan
> all the relation files to fetch a set of blocks since a past LSN.
> Hence we need some kind of LSN map so as it is possible to skip a
> one block or a group of blocks (say one LSN every 8/16 blocks for
> example) at once for a given relation if the relation is mostly
> read-only.

So, in this thread, I want to focus on the UI and how the incremental
backup is stored on disk.  Making the process of identifying modified
blocks efficient is the subject of
http://postgr.es/m/CA+TgmoahOeuuR4pmDP1W=JnRyp4fWhynTOsa68BfxJq-qB_53A@mail.gmail.com

Over there, the merits of what you are describing here and the
competing approaches are under discussion.

-- 
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company