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Re: [Issue 1585] Deltified dumps for archival and schema conversion

From: Mikhail Terekhov <termim_at_charter.net>
Date: 2004-06-18 22:09:56 CEST

kfogel@collab.net wrote:

>termim@tigris.org writes:
>
>
>>http://subversion.tigris.org/issues/show_bug.cgi?id=1585
>>
>>------- Additional comments from termim@tigris.org Fri Jun 18 10:21:09 -0700 2004 -------
>>I completely agree with Greg. Current dump file format makes dump/load
>>useless for large progects. For example I have a test project which dump file
>>is around 43Gb. It takes _10 days_ to load this file and makes it almost
>>impossible to switch from CVS to SVN for such a big project.
>>
>>
>
>Note that loading this dumpfile probably won't be any faster with
>compressed deltas. (It might even be slightly slower, I don't know.)
>
>
That would be very surprising! The closer dump format reflects internal
DB structure
the faster should be dump/load operations IMHO. Storing file deltas
instead of full file
content should eliminate applying deltas on dump and calculating them on
load.

>Is it 10 days or the 43GB which makes it impossible to convert your
>project (with cvs2svn, I presume, though you didn't say)? The 43GB
>shouldn't matter, as you can convert without having a full
>intermediate dumpfile at any point.
>
10 days of course! Profiling with oprofile shows that more than 33% of
this time is spent
in libsvn_delta (vdelta), around 9% in reiserfs, about 8.5% in
libaprutil-0(MD5Transform)
etc. From this I suppose that most of the time in cvs2svn conversion is
spent on calculating
deltas which we already have from cvs.

Mikhail
Received on Sat Jun 19 08:23:47 2004

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