Splitting out project from repo

[Jonathan Petersson]

I've a repository that's grown incredibly big and we're going to start
breaking out each project in the repo to separate repos. However I've
ran into a couple of issues in regards of Node-copyfrom-rev which
doesn't match up properly upon dump/load resulting in the following:

svnadmin: E160006: Relative source revision -18169 is not available in
current repository
svnadmin: E160013: File not found: transaction '37-1c', path
'tags/1.6.1/file.php'

I've done some efforts to rewrite the dump-files and
revision-definitions but it doesn't seem to match up properly making
it hard to automate the process. Any suggestions of changes are
welcome, please notice however that using svndumpfilter isn't really
an option due to the size of the repo it takes hours to break out just
a single project and this repo contains several thousand.

#!/bin/bash

project=$1
repo=/root/svn-copy/oldrepo
rm -fr $project*
mkdir $project
cd $project
svnadmin create $project
i=1
svn log file://$repo $project | grep -e ".*r[0-9].*|.*" | awk '{ print
substr($1,2) }' | sort -g | while read rev; do
revs[$rev]=$i
svnadmin dump $repo --quiet -r $rev --incremental >> $project.$rev.bak

# Rewrite revision number to ease rewrite of Node-copyfrom
perl -pi -e "s/Revision-number: $rev/Revision-number: $i/;" $project.$rev.bak
# Rewrite node-paths
perl -pi -e "s/Node-path: $project\//Node-path: /;" $project.$rev.bak
# Rewrite Node-copyfrom-path
perl -pi -e "s/Node-copyfrom-path: $project\//Node-copyfrom-path: /;"
$project.$rev.bak

# Rewrite Node-copyfrom-rev
for rev in $(grep Node-copyfrom-rev $project.$i.bak | awk '{ print $2 }'); do
perl -pi -e "s/Node-copyfrom-rev: $rev/Node-copyfrom-rev:
${revs[$rev]}/;" $project.$i.bak
done

# Remove prop for old project-folder
sed -i "/Node-path: $project/,/PROPS-END/d" $project.$rev.bak

svnadmin load --ignore-uuid $project < $project.$rev.bak
let i=$i+1
rm -fr $project.$rev.bak
done

svnadmin setuuid $project

Please notice that the rewrite of the revision-numbers has mitigated
the node-copyfrom-rev somewhat but not entirely as it seems like
node-copyfrom-repo points incorrectly sometimes when dumping this way.

Best

[Bob Archer]

You are manually trying to modify the dump file? Is there a reason you are not using svndumpfilter?

BOb

[Jonathan Petersson]

As mentioned, the repository is incredibly huge and it would take hours for each project.

[Thorsten Schöning]

Guten Tag Jonathan Petersson,
am Freitag, 1. März 2013 um 19:54 schrieben Sie:

> As mentioned, the repository is incredibly huge and it would take hours for each project.

That's no reason at all, your computer is doing all the work. How many
hours did you try to implement your own solution to automate the
process and it doesn't work? How many hours will you continue trying?
What will happen if everything seems to work properly and some bugs in
your rewritten dump files are recognized some days after splitting
your huge repo and result in corrupted history? How many hours are
needed to check out your working copies again, change your build
process and all those things? What's the reason behind trying to split
the source repo up in one effort and not do it as time is available?
You surely worked years with your huge repo until now, why not
continue working with it for some day or even weeks?

Some ideas on your script:

> svn log file://$repo $project

If I understand correctly, you manually retrieve each version where
the given path/project has changed in any way to afterwards dump those
revisions. Why is this better/faster than using svndumpfilter with
specifying an include path, but without the need to post process the
dump files? Are you sure your approach doesn't need other paths
from the repo, e.g. other source paths from copy operations for
projects or stuff like that?

> grep -e ".*r[0-9].*|.*"

This looks really imprecise to me, I would prefer something like
grep -E -e "^r[0-9]+ | "
just to be sure to really get what I want.

> svnadmin dump $repo --quiet -r $rev --incremental >> $project.$rev.bak

Adding to revision files with >> should be impossible in your
approach.

> svnadmin setuuid $project

This should be unnecessary as you created a new repo per project and
use --ignore-uuid during loading data into the repo.

Mit freundlichen Grüßen,

Thorsten Schöning

--
Thorsten Schöning E-Mail:Thorsten....@AM-SoFT.de
AM-SoFT IT-Systeme http://www.AM-SoFT.de/

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AM-SoFT GmbH IT-Systeme, Brandenburger Str. 7c, 31789 Hameln
AG Hannover HRB 207 694 - Geschäftsführer: Andreas Muchow

[Bryon Winger]

I am going through a similar process myself and have some questions about

your concerns. I'm not trying to rock the boat, just looking fo clarity on a few

points.

 

For perspective, I am working with around 300 individual projects

in a 70+ Gb repository containing over 300k revisions.

If I understand correctly, you manually retrieve each version where
the given path/project has changed in any way to afterwards dump those
revisions. Why is this better/faster than using svndumpfilter with
specifying an include path, but without the need to post process the
dump files?

 

I personally don't see the advantage to waiting around for svnadmin dump

to process every unrelated revision. For one project, I am only concerned

with about 200 revisions, spread out over 210k unrelated revisions.

 

# This example took around 8 hours:

svnadmin dump /path/to/master | svndumpfilter --drop-empty-revs \
--re-number-revs include $PROJECT > $PROJECT.dump

# However, when I run this on the same project:

for rev in `svn log -r0:HEAD file:///path/to/master/$PROJECT | egrep \

"^r[0-9]+ |" | cut -d " " -f1`; do

   svnadmin dump --incremental -r ${rev:1} /path/to/master | svndumpfilter \

                                             include $PROJECT >> $PROJECT.dump

done

 

… I can have a usable dump file in under 30 seconds. I realize this will take

longer for larger projects, but I think it makes my point. ‘svnadmin dump’ is

still creating a full dump stream for each revision before svndumpfilter sees

that revision to decide to keep it or not.

 

Are you sure your approach doesn't need other paths
from the repo, e.g. other source paths from copy operations for
projects or stuff like that?

 

I absolutely agree with this checking for this. You can’t successfully pull out

a single path using svnadmin dump / svndumpfilter if there are copies from a

location outside of whatever you are filtering for.

 

I did notice that using svnrdump pointing to url/project seems to get

around the outside-copy-sources issue, but I think that’s another

discussion altogether.

 

> svnadmin dump $repo --quiet -r $rev --incremental >> $project.$rev.bak

Adding to revision files with >> should be impossible in your
approach.

 

Are you saying that appending to an existing dump file in general is a

problem or just with all of his node-path processing? I have had no

trouble appending to existing dump files.

 

Thanks,

Bryon Winger

[Thorsten Schöning]

Guten Tag Bryon Winger,
am Dienstag, 2. April 2013 um 23:32 schrieben Sie:

> Are you saying that appending to an existing dump file in general is a
>
> problem or just with all of his node-path processing? I have had no
>
> trouble appending to existing dump files.

I don't know if appending to a dump file is supported or not, I just
meant his revision based file naming approach.

[Bert Huijben]

                Hi,

 

The ‘svnrdump’ tool that was added in Subversion 1.7 might do exactly what you to do.

 

This tool allows creating a dumpfile from a url (E.g. file:///path/to/repos) and should skip unrelated paths for you during the repository processing.

 

You probably still want the svndumpfilter processing to drop empty revisions before loading it in a new repository.

 

                Bert

[Bryon Winger]

You probably still want the svndumpfilter processing to drop empty revisions before loading it in a new repository.

 

I believe that the current version of svndumpfilter only operates on

version 2 dump streams - which svnadmin dump produces. svnrdump

produces a version 3 dump stream and is not compatible with svnrdump.

 

That being said, I am able to get around dumping empty revisions (from a

previous dump/load) with svnrdump by running something along these lines:

 

for rev in `svn log -r0:HEAD ${url}/${project} | \

                    egrep "^r[0-9]+ |" | cut -d " " -f1`; do

   svnrdump dump --incremental -r ${rev:1} ${url}/${project} >> ${project}.dump

done

 

Basically, I am only dumping (incrementally) the revisions which actually

affect the path in question. This obviously is not as fast as doing everything

server-side, but it does appear to work around having files or directories

copied from paths outside of the particular project path. The

outside-copy-paths are dumped in full as opposed to just a simple reference

as to where it was originally copied from.

 

I would appreciate some feedback if I’m missing something or if the above

statement is inaccurate or unreliable. In my tests, everything appears to be

the same once loaded into a fresh repository, checked out in full and diffed

against the originals.

 

There is a very brief mention in the svn-book of appending to an existing

dump file, so I expect that to be safe in general. It can be found in the

“Repository Backup” section by searching for ‘appending’.

 

Thanks,

Bryon Winger

[Bryon Winger]

for rev in `svn log -r0:HEAD ${url}/${project} | \

                    egrep "^r[0-9]+ |" | cut -d " " -f1`; do

   svnrdump dump --incremental -r ${rev:1} ${url}/${project} >> ${project}.dump

done

Basically, I am only dumping (incrementally) the revisions which actually

affect the path in question.

 

I have since discoved that incrementally dumping specific revisions via svnrdump is not

as safe as I previously thought. Some paths that were copied from outside sources did not

get included because I skipped the revision in which it was copied from.

 

So to correct myself and save others frustration - don't skip revisions with svnrdump (as

in my example above) unless you absolutely know that you won't be missing anything.

 

Bryon