RCS vs. SCCS

[Larry Jones]

In article <2265 at tellab5.tellabs.com>, segel at tellab5.tellabs.com (Mike Segel) writes:
> 1) RCS uses backwards Deltas. This means that the latest
>    version contains the actual code and the earlier versions
>    are actually the delta, or changes made over the course of 
>    development.

This is mostly correct -- thus, the older the version of the file
you want, the longer it takes to get it.  It's not completely
correct because RCS uses forward deltas to handle branches.  So,
if you want a branch version, you do backward deltas to the
common ancestor, then forward deltas along the branch to the
version you want.  Thus, variant versions take even longer to
get.

>    SCCS uses forward deltas. This means that when you "check in"
>    a piece of code, the original is stored, and the later copies
>    are really deltas based on the original.

Not strictly true -- SCCS uses merged deltas.  That is, all of
the different versions are merged into a single file so that any
version can be retrieved in one pass over the file.

Bottom line is RCS can get the most recent version(s) quicker
than SCCS, SCCS can get older version much quicker than RCS.
Which is better depends, of course, on how often you do which.  I
would expect the file sizes to be similar, but I've never really
done any actual comparisons.
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