On Mon, Aug 4, 2014 at 5:15 AM, Gabriele Bartolini <gabriele.bartol...@2ndquadrant.it> wrote: > I really like the proposal of working on a block level incremental > backup feature and the idea of considering LSN. However, I'd suggest > to see block level as a second step and a goal to keep in mind while > working on the first step. I believe that file-level incremental > backup will bring a lot of benefits to our community and users anyway.
Thing is, I don't see how the LSN method is that much harder than an on-disk bitmap. In-memory bitmap IMO is just a recipe for disaster. Keeping a last-updated-LSN for each segment (or group of blocks) is just as easy as keeping a bitmap, and far more flexible and robust. The complexity and cost of safely keeping the map up-to-date is what's in question here, but as was pointed before, there's no really safe alternative. Nor modification times nor checksums (nor in-memory bitmaps IMV) are really safe enough for backups, so you really want to use something like the LSN. It's extra work, but opens up a world of possibilities. -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
