> This only affects non-sharded repositories with rev-local IDs,
> i.e. those in SVN 1.4 format. For those, it is writing 3 files
> instead of 2 per rev now.
I assume you are talking about r1560723 [1]. If I read the code correctly...
[[[
if ( (!max_files_per_dir || rev % max_files_per_dir == 0)
&& dst_ffd->format >= SVN_FS_FS__MIN_NO_GLOBAL_IDS_FORMAT)
SVN_ERR(hotcopy_update_current(&dst_youngest, dst_fs, rev, iterpool));
]]]
...hotcopy now checkpoints after every revision for all non-sharded repositories
with FSFS format >= 3. So, checkpointing happens for all FSFS format 1/2
repositories upgraded via 'svnadmin upgrade' (with linear layout), that were
not fsfs-reshard'ed or dump/loaded into a repository with newer format.
I am not aware of how many people reshard or dump/load their old repositories
after upgrade, but I did a quick benchmark for a real-world repository and on my
machine it shows 7x performance degradation with checkpointing enabled. Is it
worth the ability to re-run the backup from a checkpoint upon cancellation?
[[[
# svnrdump http://googletest.googlecode.com/svn/trunk/
# load the dump into a --compatible-version=1.3 repository
# upgrade the repository with the most recent svnadmin
# disable checkpointing, benchmark making 100 hotcopy backups:
real 0m18.741s
user 0m2.552s
sys 0m13.432s
# now enable checkpointing and repeat the benchmark:
real 2m5.793s
user 0m0.836s
sys 0m34.840s
]]]
[1] http://svn.apache.org/viewvc?view=revision&revision=r1560723
Regards,
Evgeny Kotkov
