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Re: svn:mergeinfo is acting strange

From: Stefan Hett <stefan_at_egosoft.com>
Date: Thu, 25 Jun 2015 17:01:02 +0200

Hi Chris,
> Hi,
> we've been using SVN for a large in-house project for a number of years and the longer time goes by, the more strange the svn:mergeinfo properties behave. I don't know if the "issues" are completely expected, if our repository somehow has ended up in a state that is unwanted or if there's something bug somewhere.
> What happens:
> Whenever someone merges a branch onto the trunk, there are approximately 100 files/directories that get added mergeinfo despite these files (or files under them) not being affected by the commit. That the root directory of the trunk should be modified makes perfect sense to me, but if my merge only affects src/foo/bar.txt, why does it then have to set mergeinfo on e.g. test/some/untelated/thing.txt?
> It seems to be the same set or files/dirs that always get tagged with additional information, so I suspect that some previous merge has made these specific files add all future mergeinfos into them, while other files that didn't get this strangeness stay unaffected. E.g. I have two source files in the same directory: File1 has 367 lines of mergeinfo (367 different branch merges, that is), file File2 has 0. And both these files are equally old, so it makes no sense that they should differ that way.
> Is this expected or has our repository become overzealous?
> If the latter: can I "fix" this situation by manually deleting the mergeinfo from files "further down in the tree"? And if I do that, how badly will upcoming branch merges be affected?
> This isn't a major issue, but there have been cases where we've had conflicts inside the mergeinfo in these "special files" which has been sort of difficult to resolve for some committers. It is also quite annoying that every time we do "svn update" after a merge, we get 100+ lines of updates even if just one file has been modified (especially annoying in tools like subclipse).
> TIA,
> Chris

We are facing exactly the same issue. I just got through dealing with
this on our case using a tool written by the SVN developer Stefan
Fuhrmann to get rid of redundant/unnecessary mergeinfo entries. It can
be downloaded from the svn-mergeinfo-normalizer branch in the SVN
repository. The tool is located under
tools/client-side/svn-mergeinfo-normalizer. The branch readme provides
some basic information about what the tool does and how it can be utilized.

In principle it provides the following functionality (all done on a WC):
- analyzing the mergeinfo and reporting whether certain nodes can be
combined (and if not, what presents it from being combined)
- normalize the mergeinfo (basically removing redundant mergeinfo
entries on nodes)
- combine-ranges to combine the recorded revisions to a shorter but
semantically equal representation
- clear-obsoletes to drop mergeinfos for branches which no-longer exist

Since you asked: I guess in most cases the reason for recording
additional mergeinfos is because (for some other reason) you ended up
with adding mergeinfos on a subnode (for instance
As per definition of mergeinfos once a node (like thing.txt in ur case)
contains mergeinfo, it needs to contain all the relevant mergeinfo in
its own node. This is due to performance reasons as far as I understand
it, so that if u want to determine which revisions got merged into a
node, SVN only has to check out this one mergeinfo entry, rather than
going up the tree to determine which things got merged into this one.

The good question here is why does it even keep record for revisions the
node is not impacted by. I asked the same question in February already
on this list (see: inconsistency between mergeinfo records). As far as I
understand this is done atm to keep the application design simple. There
are cases where the additional mergeinfo is required on nodes (for
instance when adding a new file in a directory, the record needs to be
kept on the directory node so the mergeinfo is correct). Effectively
things could be improved (and as far as I've read here, it's on the
radar for a later version), but the current behavior is as it stands
right now.

If u're running under Windows and want to give the
svn-mergeinfo-normalizer tool a try, I could send u the executable I've
compiled and am using myself here.

Received on 2015-06-25 17:01:10 CEST

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