On Wed, Jan 27, 2016 at 1:54 PM, Stefan Fuhrmann <eq...@web.de> wrote: > On 27.01.2016 13:08, Johan Corveleyn wrote: >> >> On Mon, Sep 28, 2015 at 12:16 PM, <stef...@apache.org> wrote: >>> >>> Author: stefan2 >>> Date: Mon Sep 28 10:16:12 2015 >>> New Revision: 1705646 >>> >>> URL: http://svn.apache.org/viewvc?rev=1705646&view=rev >>> Log: >>> Tune reorg strategy during the FSFS format7 packs such that it favors >>> checkout-style tree walks now. >>> >>> Since r1703237, following the log history no longer requires frequent >>> access to directory data but mainly relies on noderev predecessor chain. >>> Therefore, it is no longer necessary to tightly pack directories in a >>> separate part of the pack file. With this patch, they are now placed >>> with the file contents and can be processed by a quasi-linear scan >>> instead of reading from two sections per pack. >>> >>> * subversion/libsvn_fs_fs/pack.c >>> (compare_dir_entries_format7): Adapt reporting strategy - process dirs >>> at the same time as files now. >>> (compare_is_dir): No longer needed. >>> (sort_reps): No longer distinguish between file and dir reps but only >>> paths and delta chains when determining reprentation >>> order. >> >> >> Hi Stefan, >> >> In this post-1.9.x-branch commit (and a couple of subsequent >> pack-related commits) you changed the pack layout for FSFS format7, to >> make it more efficient for exports, checkouts, ... > > > The benefit is not massive and very much depends on > project vs. repository size. 20% or so for SVN. > >> I'm wondering, when 1.10 comes out, how will I be able to benefit from >> this improved pack layout? Supposing I've already dump/load-ed with >> 1.9 in FSFS7, and packed it. > > > Future commits will use the new strategy. So, speed > will slightly go up over time. > >> Does this require a format bump (and another dump/load)? Or do you >> plan on providing a way to "repack" (or simply unpack and pack) a >> packed repository? Currently there is no unpack or repack command ... > > > This is no format change; the beauty of format 7 is > that we can learn and tweak strategies as we go without > a format bump. OTOH, there is not much potential for > further improvement right now. FSFS is limited by its > fixed sharing scheme. > > I have no *plans* for unpack/repack but the thought > has occurred to me. It should not be hard to do as > an offline operation, maybe alongside a reshard command. > If you want to write an 'svnadmin unpack', I'd support > you in that effort.
Interesting :-). I've put it on my radar, but not sure if I'll ever get to it. Life keeps getting in the way ;-). Would be a nice bite-sized task though ... if someone else wants to have a go, feel free. Maybe it's something to put on the http://subversion.apache.org/ideas.html page? -- Johan
