All change comments to perforce branch between 2 labels? (including merges) - version-control

Question

Our perforce admin limits "max-row" scans so that my first idea of running the following will not work:
All changes including integrates into a branch at particular label time 1
All changes including integrates into a branch at particular earlier label time 2
Subtract time 2 changes from time 1 to get the new changes with comments.
Is there an alternative way of getting the same result without having such a massive query(when perforce contains 7yrs of history and -i triggers a scan back to the dawn of history)
Based on Gregs comments added this comment:
Basically the point is to see what bugs got fixed in a particular release branch between 2 labels(or more commonly, some old label and today).
I wish to simplify(speedup) way too complex script that we currently have which looks at changes that went into a release branch, it follows files that went into them at least 2 branches up in order to printout all the changeset comments from the original change(the interim merge comments tend to just say something like merge123 etc instead of description of the actual change comments, so we need to walk up the tree to the original comment as well), script finally outputs something like below(we put quality center IDs into changeset comments):
qualityCenterId123 - fixed some bug
in gui qcId124 - fixed some other
bug qcId125 - fixed some other bug
merge123
UPDATE based on comments:
Problem with Toby's approach is that most of the changes into the code branch came via integrations, -i would include those change, but as stated that explodes the query to such a degree that due the load on perforce server our admin won't allow it to run. So this is why I am looking for an alternative approach to get the same result.

Answer 1

I can't see an easy answer to this, but do have a couple more suggestions that perhaps may help point in the right direction.
Persuade your admin to raise the maxscan rows limit. If he is nervous that this will lead to problems with the whole user base, just get him to add you to a new user group (e.g. "Scripting"), and set the limits for just that group. That will have the effect that only members of that group can use the upper limits, and you can then negotiate for suitable times to run the script. You could even do it overnight.
Have a look at the P4 admin guide and see if any of the hints on scripting will help - e.g. maybe a tighter view on the data will limit the query enough to not break the maxscanrows limits.
How's your SQL? You may be able to construct an efficient query using the P4Report tool.
Try asking the question on the Perforce mailing list. It's a very active list that has a lot of very experienced people who are very helpful. See this link for the sign-up page. There's a good chance that they will suggest some good approaches.
Probably too late for yoru existing labels, but consider using the job system to track work. Perforce has inbuilt query tools to track what jobs have made it into different branches. It does require a working-practice change for your team, however.
Sorry I can't provide a more specific answer.

Answer 2

Are your labels more than simply the most recent changelist when they were created? Eg did you really need to record specific files in client workspaces? If not you can very easily compare the two changelists closest to labels.
Say the closest change to your first label date is 23000 and your closes change to your second label date is 25000 then
p4 changes //depot/PATHTOMYCODE/...#23000,#25000
will give you all changes to your code path between these two changelists.

Answer 3

Won't a normal Label-diff do what you want?
From P4V, Tools->Diff. Select the two labels
From P4Win, right click label, select diff files in 2 labels
From command line, p4 diff2 //codeline/...#label1 //codeline/...#label2
Or am I missing exactly what you are after?
Further suggestion after Ville's comment on the above
If you are only after the info per changelist, rather than per file, then try "p4 interchanges" from the command line. This will give you just the summary of what changes in one branch have not happened in another, and you can supply a revision range to limit it to the labels you need.
Do "p4 help interchanges" from command line for details.
Unfortunately the interchanges command is not yet exposed in P4V or P4Win.

Answer 4

Toby Allen's Answer is the best approach if your labels are simple changelists.
If the labels are more complicated, then I think you need to look at all the files in each label and where their versions differ, find the changelist where the version changed.
You can get the file and version lists with:
p4 fstat -Of //...#MyLabel
EDIT:
Consider two complex labels:
VERSION_A:
//depot/file_A.cpp#4
//depot/file_B.cpp#7
//depot/file_C.cpp#1
VERSION_B:
//depot/file_A.cpp#6
//depot/file_B.cpp#5
//depot/file_C.cpp#4
In this example, the labels do not describe a particular changelist, the head change for each file may be different.
If you can have labels like this, then you can run the p4 fstat command on each label and then find the differences. In this example, file_A.cpp has changed twice and file_C.cpp has changed 3 times. file_B.cpp is older in the second label, so it can be ignored.
So now you need to look at the changes that involved these versions:
file_A.cpp#5
file_A.cpp#6
file_C.cpp#2
file_C.cpp#3
file_C.cpp#4
Those changes can be retrieved with p4 filelog, so you want to run something like this:
p4 filelog file_A.cpp#6
p4 filelog file_C.cpp#4
Then you need to remove any duplicates and any history for earlier versions.
Like I said, you only need this if you have messy lables. If there's any way to make your labels represent changelists, you should use Toby Allen's answer.