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Re: Will upgrade from 1.6 to 1.7 benifit from dump/reload?

From: Johan Corveleyn <jcorvel_at_gmail.com>
Date: Mon, 22 Feb 2010 14:28:32 +0100

On Mon, Feb 22, 2010 at 1:35 PM, Neels J Hofmeyr <neels_at_elego.de> wrote:
> (This mail was posted to dev@ -- redirecting to users@)
> Johan Corveleyn wrote:
>> Hi devs,
>> A small question in anticipation of 1.7: will an (FSFS) repo benifit
>> from a dump/reload when upgrading from 1.6 to 1.7? Or will a simple
>> "upgrade" (followed maybe by a "pack" to pack the revprops) provide
>> just the same?
>> Reason for asking: We're currently still running on 1.5, and planning
>> to upgrade to 1.6 soon. Tests have shown us that doing a dump/reload
>> during this upgrade will give some benefit (due to rep-sharing
>> probably), but nothing huge. So I'm just wondering whether to do a
>> dump/reload now (to be in the best possible shape for the future), or
>> that I'll have to do another dump/reload when going to 1.7 in order to
>> get maximum benifits. In the latter case, I will probably not do a
>> dump/reload now (just upgrade to 1.6), and defer that until we upgrade
>> to 1.7...
>> Kind regards,
>> Johan
> Just a side note, we are expecting most users to still be using 1.6 servers
> with their 1.7 clients for a while. But 1.7 will probably move to SHA1
> checksums instead of MD5, and there will be some duplicate checksum
> calculation when pairing up a 1.7 client with older servers. ...but a)
> duplicate checksums might also be necessary even with 1.7 client <-> 1.7
> server, and b) we don't expect *that* to impact performance, really.
> 1.7 servers may also allow you to obliterate revisions, but we don't know
> that yet.
> Anyone else know of a particular server side improvement planned for 1.7?
> (I'm rather ignorant, really)

Thanks for your answer, Neels. But it doesn't really answer my question :).

I was not asking whether upgrading the server to 1.7 would be
benificial, but whether *dump/reload* would provide any benifit over
just upgrading to 1.7. Of course this is really a hypothetical
question as 1.7 doesn't exist yet. But given what's currently on the
table for 1.7 (as far as it is already known). Does anyone know?

As for using the SHA1 checksum, I'm wondering if it would make any
difference whether or not you reload the repo: as of 1.6 the (FSFS)
repo already contains SHA1 hashes. If I understand the FSFS
"structure" document [1] correctly (section "Revision file format", in
the list "The following fields are defined"), as of format 4 (SVN 1.6)
it already contains SHA1 checksums for the representations. Of course,
I may be misunderstanding the doc, or misunderstanding what's going to
be needed for 1.7...

That same document currently does not describe any differences between
format 4 (SVN 1.6) and format 5 (SVN 1.7) in the section "Filesystem
formats". Which is kind of odd (why bump the filesystem format if
there are no differences)...

As for the redirection to users@: sorry if I initially picked the
wrong audience (I'm quite careful with that sort of thing, don't want
to generate noise). But in this case I just thought dev@ was the
correct forum. Although this is a "usage" question, it's about usage
of a version that nobody uses yet. I'm guessing that only the devs, if
anyone, currently have an idea what the answer will be to that
question :). Anyway, doesn't matter that much to me, but any insight
anyone can offer would still be very helpful ...


[1] http://svn.apache.org/repos/asf/subversion/trunk/subversion/libsvn_fs_fs/structure
Received on 2010-02-22 14:29:28 CET

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