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<title>The Branching Papers -- Perforce FAQs</title>
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<p>
<b>
We tried to integrate a single change from one branch to 
another but in the resolve step we saw hundreds of deltas
that weren't in this change. Why was this?
</b>
<blockquote>
Assume @123 is a changelist that was a bug fix in //depot/6.0.
And assume you used:
<pre>
   p4 integ //depot/6.0/...@123,@123   //depot/6.0.1/...
</pre>
to propagate the bug fix from //depot/6.0 to //depot/6.0.1. 
<p>
Using "@123,@123" as a revision spec in <b>p4 integrate</b> 
is saying "integrate 
from @123 to @123", which limits it to only the deltas associated with
changelist @123.
<p>
However, if this is a "leapfrogging integration" (that is, there are
changelists previous to @123 which are NOT being integrated) then the
<b>p4 resolve</b> step can be confusing unless you know what's happening. 
<p>
The thing you have to look out for is that <b>p4 resolve</b> always uses
the rev previous to the "from rev" to do the 3-way merge.
<p>
I'm sure that didn't make any sense, so here's an illustration. 
Say //depot/6.0.1 is only integrated with //depot/6.0, up as far as @100 
in //depot/6.0. Now you do a 
<pre>
   p4 integ //depot/6.0/...@123,@123   //depot/6.0.1/...
</pre>
Let's see what 
happens to //depot/6.0/foo.c:
<p>
<ul>
<p><li>
    //depot/6.0/foo.c is being integrated into //depot/6.0.1/foo.c

<p><li>
    the 'yours' file in the <b>p4 resolve</b> will be //depot/6.0.1/foo.c at
    its current revision on your client

<p><li>
    the 'theirs' file in the <b>resolve</b> will be //depot/6.0/foo.c@123

<p><li>
    BUT LOOK: the 'base' file will be //depot/6.0/foo.c@122

</ul>
<p>
This means that fixes in 6.0/foo.c after @100 and before @123 will appear
as "backing out" diffs in the resolve step. When you look at the
'diff yours' output, all deltas from @101 to @122 will look like they're
being backed out of the 6.0.1/foo.c file.
<p>
The thing is, even though the diffs LOOK like they're being backed out,
they're not really, because they were never in the 6.0.1/foo.c file to begin
with. But since they're in the base file, you see them in the resolve 
process.
<p>
As long as you expect this, it's not a problem, but most people are 
completely thrown the first time they see it. (That's why I usually try
to discourage shops from doing leapfrogging integrations, but sometimes they
just can't be avoided.)
</blockquote>
<p>
<i>(March 1998)</i>
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#	Change	User	Description
#1	1424	Michael Roach	Creating initial guest branch of perforce\faq\...
//public/perforce/faq/br02.html
#1	112	Laura Wingerd	Publish "Branching FAQ" (pull in changes from //guest/laura_wingerd/perforce/faq/... )
//guest/laura_wingerd/perforce/faq/br02.html
#2	85	Laura Wingerd	Correct typos and add a few clarifications.
#1	83	Laura Wingerd	The Branching Papers.