Path: utzoo!utgpu!water!watmath!clyde!att!osu-cis!tut.cis.ohio-state.edu!husc6!cca!g-rh From: g-rh@cca.CCA.COM (Richard Harter) Newsgroups: comp.unix.questions Subject: Re: RCS and SCCS Message-ID: <29953@cca.CCA.COM> Date: 25 Jun 88 14:32:05 GMT References: <890@fig.bbn.com> <710@ubu.warwick.UUCP> <661@pyuxe.UUCP> Reply-To: g-rh@CCA.CCA.COM.UUCP (Richard Harter) Organization: Computer Corp. of America, Cambridge, MA Lines: 36 In article <661@pyuxe.UUCP> mayerar@pyuxe.UUCP (80132-A Mayer) writes: >In article <710@ubu.warwick.UUCP> maujd@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.