Hyrum K. Wright wrote on Fri, May 06, 2011 at 07:49:08 -0500: > On Thu, May 5, 2011 at 7:27 PM, Loren M. Lang <lor...@north-winds.org> wrote: > > On Fri, 2011-05-06 at 00:37 +0300, Daniel Shahaf wrote: > >> Loren M. Lang wrote on Thu, May 05, 2011 at 14:32:37 -0700: > >> > On Thu, 2011-05-05 at 15:43 +0300, Daniel Shahaf wrote: > >> > > Loren M. Lang wrote on Wed, May 04, 2011 at 17:39:57 -0700: > >> > > > The format file says 3 so I might have made it with 1.3.x. > >> > > > >> > > This conclusion is wrong. The format number is NOT the minor release > >> > > number (because we may bump it multiple times between successive minor > >> > > lines). > >> > > >> > Is there a list of these format numbers and their meanings/features? > >> > I'm curious what I missed by not upgrading to 4 when I had the chance. > >> > > >> > >> https://svn.apache.org/repos/asf/subversion/trunk/subversion/libsvn_fs_base/fs.h > >> https://svn.apache.org/repos/asf/subversion/trunk/subversion/libsvn_fs_fs/fs.h > >> https://svn.apache.org/repos/asf/subversion/trunk/subversion/libsvn_fs_fs/structure > > > > There appears to be some confusion here. I was referring to format > > under the repository root. The references you gave me appear to refer > > to db/format. My original 1.4.x repository had format = 3 and db/format > > = 1. When I created the new repositories, format was bumped to 5. I do > > not know what db/format was as I already deleted them, but I'd assume > > db/format for the 1.5.x fsfs repository was 3. > > > > My primary question though, was simply whether bdb was normally as > > space-inefficient as my test showed and whether I should consider it > > over fsfs for Subversion 1.5.x or 1.6.x+. > > Prior to 1.6.x, bdb stored full-texts at HEAD, and deltified > backwards, whereas fsfs has always stored an initial full-text and > deltified going forward. This creates a situation that when nodes are > copied (usually via a branch), you can get multiple fulltexts which > are roughly the same, rather than multiple deltas. This is one of the > major reasons the bdb backend takes more space. > > In 1.6, bdb was changed to use the same deltification scheme as fsfs. > As a result, after bdb-backed repositories are upgraded to the 1.6 > format, they will begin to use forward deltas.
Clarification: upgraded repositories will use forward deltas (FSFS-direction-deltas) only for new data, not for historical data. > Dumping a loading in this case will cause forward deltas to be used > repo-wide, i.e., in historical revisions too > thus resulting in space savings. > > But really, if you're going to dump / load a bdb repository, why not > just use fsfs? > > -Hyrum
