RCS and SCCS

[Richard Harter]

In article <661 at pyuxe.UUCP> mayerar at pyuxe.UUCP (80132-A Mayer) writes:
>In article <710 at ubu.warwick.UUCP> maujd at warwick.UUCP (Geoff Rimmer) writes:
>>Which out of RCS and SCCS do people prefer?  I found rcs(1) by mistake
>>in a manual page in our computer unit library - and I've found it very
>>good.  What are the good and bad points of each system?
>>
>>Geoff.
>
>One good point of RCS is that it stores the most recent version and 
>uses deltas to get back to the previous versions.  SCCS stores the
>original version and uses deltas to get to the most recent version.

	This is misleading.  RCS stores the most recent version and
uses reverse deltas; that is true.  The quoted material suggests that
SCCS gets the latest version by taking the base and applying all
intervening deltas (it doesn't say this but the implication is there).
This is not true; SCCS does not work that way.

	SCCS uses what is sometimes known as interleaved deltas and is
sometimes known as the selectable change model.  The deltas are not 
stored separately; they are integrated into the controlled source.
I won't go into the details on how this is done; the effect is that
the cost of extracting *any* version is proportional to the total
number of lines ever present in the controlled text.  The cost of
extracting a version is greater with SCCS, but only modestly so.

	The principle differences between RCS and SCCS are the
commands and issues dealing with interacting with make.  Most people
rate RCS as being easier to use than SCCS.  Neither is entirely
adequate for complex version control problems, but SCCS can do more
along those lines than RCS can.
-- 

In the fields of Hell where the grass grows high
Are the graves of dreams allowed to die.
	Richard Harter, SMDS  Inc.