On 15.02.2018 22:11, Daniel Shahaf wrote: >> With say, 100000 revisions, when someone checks out the last revision: >> svn starts (would start, with the FSX backend) >> with the 30 years old, "fossile" ancient revision? (It would be case >> with the "FSFS-like way".) Which has nothing common >> with the recent revisions? And applies (at least) 17 deltas (patches)? >> Of which many deltas are very "heavy" (huge >> changings, complete rewritings)?.. I would marvel at that and do not >> understand the reasons.. > Note that when the delta is larger than the file it results in, > Subversion stores a compressed fulltext rather than a delta. Your > example of a file that has undergone multiple complete rewrites might > exercise that logic, which will shorten the walk. > > I'm not sure why you say "at least" 17 deltas. The default value of > max-linear-deltification (see fsfs.conf) is 16, meaning that no fulltext > will require 17 delta applications to produce.
Another important thing to note is that the deltas are not applied in series; they are _combined_ in series and then the resulting combined delta is applied to the initial fulltext. Combining deltas is (in general) lot cheaper than applying them. -- Brane
