On Thu, Jul 3, 2014 at 2:06 PM, <m.roth at 5-cent.us> wrote: > Lists wrote: >> On 07/02/2014 12:57 PM, m.roth at 5-cent.us wrote: >>> I think the buzzword you want is dedup. >> dedup works at the file level. Here we're talking about files that are >> highly similar but not identical. I don't want to rewrite an entire file >> that's 99% identical to the new file form, I just want to write a small >> set of changes. I'd use ZFS to keep track of which blocks change over >> time. >> >> I've been asking around, and it seems this capability doesn't exist >> *anywhere*. > > I was under the impression from a few years ago that at least the > then-commercial versions operated at the block level, *not* at the file > level. rsync works at the file level, and dedup is supposed to be fancier. > Yes, basically it would keep a table of hashes of the content of existing blocks and do something magic to map writes of new matching blocks to the existing copy at the file system level. Whether that turns out to be faster/better than something like rdiff-backup would be up to the implementations. Oh, and I forgot to mention that there is an alpha version of backuppc4 at http://sourceforge.net/projects/backuppc/files/backuppc-beta/4.0.0alpha3/ that is supposed to do deltas between runs. But, since this is about postgresql, the right way is probably just to set up replication and let it send the changes itself instead of doing frequent dumps. -- Les Mikesell lesmikesell at gmail.com